Transfemoral Amputation: Prosthetic Management Mark David Muller, CPO, MS, FAAOP

Chapter 46 Transfemoral Amputation: Prosthetic Management Mark David Muller, CPO, MS, FAAOP

implementation techniques for trans- Abstract femoral socket design, suspension, and Clinicians have long strived to create optimal transfemoral prosthetic designs that will clinical application. not only enhance the user’s ability to ambulate but also will be a functional element of the One rationale for the differing de- individual’s life. Although there have been many advancements in materials, socket designs, and components, there has been little research to help quantify how the individuals that use signs may be the variability observed in these prosthetics devices can best be served. It is helpful to explore clinical considerations the anatomy, size, and length of trans- and anticipated outcomes when creating transfemoral prosthetic devices. Prosthesis use is femoral residual limbs, as well as the aff ected by many factors, including energy expenditure, body image, voluntary control within level of voluntary control the individual a transfemoral prosthetic system, socket fi t and design, component selection, and alignment. possesses. It is accepted that no single design is appropriate for every individual with a transfemoral amputation. Keywords: prosthetics; transfemoral alignment; transfemoral Accordingly, variations in the clinical prosthetic socket; transfemoral prosthetic suspension applications of formalized training have led numerous practitioners to create Introduction clinical standards of practice for device unique styles and techniques.9,10,16,17 Amputations at the transfemoral level creation, fi t, suspension, and alignment. These variations provide practitioners account for approximately 19% of the Throughout history, transfemoral design with the ability to adapt a transfemoral approximately 1.6 million individuals and fabrication techniques have been socket to best meet the needs and goals in the United States who are currently passed down from mentors to protégés, of an individual patient. living with an amputation.1-3 Statistics with no formal instructional cours- The common clinical goals and con- from 2004 reported that 31% of all ma- es available in the United States until siderations that guide rehabilitation jor amputations were performed at the 1949 when the University of California professionals through this patient-spe- transfemoral level,4,5 with new evidence at Berkeley introduced a short course in cifi c process are discussed in this chap- showing a decrease in the number of transfemoral design of a suction sock- ter along with an overview of current transfemoral amputations performed et. In the 1950s, several universities transfemoral socket designs and the each year.2 There also is evidence that began formal education programs in implications of suspension, alignment, individuals who have undergone am- prosthetics, with each school creating and biomechanical considerations in putation are living longer and will re- their own laboratory manuals and de- evaluating, fabricating, and fi tting trans- quire prosthetics services throughout sign iterations.13 The prevalent design at femoral prostheses. their lives.1,6 In 2014, certifi ed prosthetic that time was the German transfemoral practitioners spent more than 25% of quadrilateral socket, which used skin Clinical Considerations and their time caring for patients with a suction suspension.14,15 In the 1980s, Anticipated Outcomes transfemoral amputation.7 the fi rst ischial containment manual Although prosthetic devices will never Those in the fi eld of prosthetics emerged and was quickly adapted by truly replace a missing limb, certain have a long history of involvement with other institutions, although each insti- clinical considerations must be ad- transfemoral prosthetic socket design tution implemented design iterations. As dressed, irrespective of which socket or and construction, with the fi rst patents of 2014, there were 11 accredited institu- suspension design is chosen. The trans- awarded in England in 1790 and the tions offering master level education for femoral prosthetic system must balance fi rst US patent for a transfemoral arti- prosthetic and orthotic practitioners in function, comfort, and appearance both fi cial limb given in 1846.8-12 However, the United States, with each institution dynamically and statically.8,11,12 To prosthetists still do not have universal offering differing theories and practical create the most appropriate plan, the treating team must consider energy ex- Mr. Muller is the owner of K&M Clinical Services LLC. penditure, body image, the user’s level

of voluntary control, and the fi t of the integrate with peers plays a large role in component choice and alignment prosthetic socket. In implementing the an individual’s positive adaptation to his considerations. treatment plan, the team must deter- or her altered body image and psycho- mine socket construction and design, social adjustment.24 Body image anxiety Fit of the Prosthetic Socket the degree and complexity of the sus- increases depression, reduces perceived The ideal goal for any prosthetic device pension system, the appropriate com- quality of life, lowers self-esteem, re- is for the user to feel that the device is ponents, alignment considerations, and duces participation in physical activity, part of his or her body. Irrespective of outcome measures. and lowers overall satisfaction.25,26 The the socket design, an optimal fi t should prosthetist must create a device to maxi- be intimate to the contours of the residu- Energy Expenditure mize the confi dence of the user through al limb and assist the user in controlling Energy expenditure for a transfemoral optimal fi t, suspension, function, and the prosthesis. Beyond these basic cri- amputee is of great concern. The effort alignment symmetry, as well as an ac- teria, an optimal fi t of a transfemoral required to ambulate with a prosthetic ceptable energy expenditure.27 There is prosthetic socket is poorly defi ned and device at this level is dependent on the a growing trend toward user participa- has not been standardized. However, if weight of the device, the quality of fi t, tion in aesthetic choices, including real- users do not feel that they have control the degree of suspension, the accuracy istic silicone covers, water transfers, or of the socket, they likely will not fully of alignment, and functional character- three-dimensionally printed cosmeses. use the prosthetic device.28,31 istics of the chosen components.17-21 If These choices may help the user feel Radcliffe14 suggested that the prima- any one of these factors is not prop- more involved with the creation of his ry goals of a transfemoral prosthesis are erly addressed, the individual using or her prosthesis and thus increase de- to achieve comfort in weight bearing, a transfemoral prosthesis will exhibit vice acceptance.24,28 provide a narrow base of support in higher levels of energy expenditure standing and walking, and accomplish during ambulation than are neces- Effect of Voluntary Control the swing phase of gait in a manner that sary. Increased energy expenditure is Functional ambulatory goals will be is as close to normal as possible. The fi t accompanied by an increase in the rate defi ned by the individual’s ability or and orientation of the socket are par- of oxygen consumption and an associ- potential to control the transfemoral amount in achieving these goals. The ated elevation in heart rate. An elevated prosthetic device. This is commonly socket must be donned in the correct heart rate can, in turn, lower the user’s known as the level of voluntary con- orientation with respect to the user’s line self-selected walking speed and reduce trol.9,10,14,29,30 Because the user will of progression, must match the volume gait effi ciency.22 For elderly individ- not have direct musculoskeletal con- of the residual limb, and must create an uals with a transfemoral prosthesis, trol of the prosthetic knee and foot, environment of total contact without the physical burden of ambulating a determination of his or her poten- causing impingement or discomfort. The with a prosthetic device may exceed tial voluntary control is an impor- socket also should provide adequate sta- their abilities, leading to a lower rate tant consideration in determining the bility in the sagittal, coronal, and trans- of prosthetic use.20,23 Knowing that am- socket style, interface, suspension, and verse planes throughout the gait cycle. bulation with transfemoral prosthetic components used. Factors that deter- devices requires high levels of energy, mine the degree of voluntary control Importance of Orientation practitioners must create treatment include residual limb length, position- When donning the socket, the orien- plans that meet the individual’s needs al awareness in space, active range of tation of the socket must match the and goals with an acceptable burden motion, muscle strength, and the ul- user’s residual limb and adjacent bony level. timate ability to manipulate the limb structures. If the socket is malaligned, in a controlled and deliberate manner. the device will rotate and cause undue Body Image When voluntary control is limited, pressure on the limb or the pelvis. To Body image and appearance when using the rehabilitation team should design properly integrate the limb within the a transfemoral prosthesis are complex prosthetic systems that focus on pros- socket, the individual should be in- considerations and should be addressed thetic support and patient safety rath- structed regarding socket orientation as within the treatment plan. It is impor- er than function and performance. In it relates to his or her anatomy. This ana- tant to realize that appearance and contrast, enhanced voluntary control tomic reference differs for the varying self-image can be a cosmetic as well as allows for the design of a more dynam- socket designs but must be addressed, a functional concern. An acceptable ap- ic prosthesis. The degree of voluntary especially in the initial and subsequent pearance and the ability of the user to control also plays an integral role in fi ttings of the device.

Importance of Total Contact Socket Fit expenditure, gait deviations, and dis- Coronal Plane There are various techniques to as- satisfaction with the prosthesis.23,35,36 In the coronal plane, prosthetic control is sess whether the volume of the socket critical in limiting the movement of the matches the volume of the residual limb. Sagittal Plane torso laterally over the prosthetic device Most techniques rely on a combination The principles of prosthetic control in during the single-limb support phase of of visual verifi cation through a clear the sagittal plane are best considered the gait cycle. This compensatory lateral diagnostic interface and a determina- in the early stance phase of the gait cy- movement over the prosthesis is one of tion of internal socket pressure through cle. As the prosthetic foot contacts the the most common prosthetic gait devi- visual examination, tactile probes, or fl oor, the ground reaction force quickly ations seen in the user of a transfemo- electronic pressure sensors. Irrespec- moves posterior to the mechanical knee ral prosthesis.38 Unless a hip abduction tive of the technique, it is imperative joint center and creates an external contracture is present, the residual fe- that pressures are balanced and can be knee fl exion moment that will cause mur should be placed in an adducted tolerated by the user.16,32 The prosthe- the prosthetic knee to buckle if it is not position equal to the contralateral femur. tist should ensure that all areas within adequately controlled by the user. The This position ensures the effi cient fi ring the socket make contact because lack ipsilateral hip extensor musculature of of the hip abductor muscles on the am- of contact may result in edema, socket the individual must fi re, pulling the re- putated side, which limits contralateral migration, and compromised control of sidual femur and the prosthetic socket pelvic drop and associated lateral trunk the prosthesis. posteriorly to create a counterextension bending. This is accomplished by fi t- The tissues proximal to the trim moment and stabilize the mechanical ting a fl attened lateral socket wall that is lines must be free from impingement knee.37 Importantly, the residual femur countered by a suffi ciently high medial throughout gait and while seated. Tis- must be adequately stabilized within socket wall aligned in the correct angle sue bulging over the proximal trim the socket before the actions of the hip of femoral adduction.14,30,39,40 lines can lead to skin breakdown, ede- extensors can be translated through During the initial fi tting of a trans- ma, subdermal cysts, blisters, irrita- the prosthesis to act on the ground. In femoral socket, the proximal coronal tion, and discomfort.33 Similarly, there the absence of such femoral stabiliza- instability of the socket can be easily must be adequate relief for the bony tion, the contractions of the hip exten- determined by performing the lateral structures within the socket. Pressure sor muscles are less effective, and the and the medial displacement tests. For on the ischial tuberosity, ascending ability to control the prosthetic knee is both of these assessments, the prosthe- pubic ramus, adductor longus tendon, compromised, causing the individual sis user must be standing safely with- greater trochanter, or distal femur can to compensate with a reduction in step in parallel bars. To perform the lateral lead to socket rotation, pain, gait de- length, a slower cadence, or an ante- displacement test, the prosthetist places viations, or rejection of the prosthetic rior shift in body weight. All of these one hand on the proximal lateral brim of device.34 compensatory actions increase energy the transfemoral socket while the other expenditure. hand is placed on the prosthesis user’s Socket Stability Prosthetic control in the sagittal ipsilateral iliac crest. Gently but fi rmly, Stability of the transfemoral prosthetic plane should also be considered in late the prosthetist then pushes medially on socket on the limb is vital to the con- stance. During this phase of the gait the iliac crest while also pulling lateral- trol of the device. The prosthetist will cycle, the individual must engage the ly on the proximal brim of the socket. make a clinical determination on the hip fl exors to drive the prosthetic socket If the socket displaces more than 0.5 type of socket design based on the in- anteriorly. This hip fl exion action creates inch (1.27 cm) from the residual limb dividual’s level of voluntary control and prosthetic knee fl exion, thereby lifting during this static test, the socket may the stability required. Individuals with the overall prosthesis off the ground to also displace laterally during single-limb greater levels of voluntary control are initiate the swing phase. Inadequate stance in gait. This lateral displacement less dependent on socket modifi cation, femoral stabilization may delay the ex- often suggests coronal instability in the component choice, and alignment ac- ecution of this action, resulting in a loss socket, and it can cause the individual commodations to control unwanted of control of the prosthetic knee and po- to experience excessive proximal medial socket displacement during ambulation. tential compromise of its function. The pressures on his or her residual limb. Excessive motion of the transfemoral individual will likely display a shortened A compensatory lateral shift of the tor- prosthetic socket on the residual limb step length, reduced speed of ambula- so may be adopted to restore coronal in the sagittal, coronal, and transverse tion, and a lack of confi dence with the stability and reduce these pressures planes can lead to increased energy prosthetic device.28,31 (Figure 1).

Figure 1 Illustrations of the steps in the lateral displacement test. After donning, the socket is aligned with the line of progression and checked to ensure a total contact fi t and a level pelvis. The prosthetist then can test for lateral displacement of the socket on the limb. A, One hand is used to grasp the proximal edge of the socket while the other hand is placed on the ipsilateral iliac crest to provide a counterforce and stabilization. B, The proximal socket is pulled laterally until displacement stops. C, The ideal amount of displacement is 0.5 inch (1.27 cm) measured from the skin to the socket wall. If the displacement is greater than 0.5 inch (1.27 cm), the transfemoral socket likely will be unstable in the coronal plane during single-limb support.

Figure 2 Illustrations of the steps in the medial displacement test. After donning, the socket is aligned with the line of progression and checked to ensure a total contact fi t and a level pelvis. The prosthetist then can test for medial displacement of the socket on the limb. A, One hand is placed over the proximal-lateral aspect of the socket and the other hand is placed over the greater trochanter on the contralateral side. B, Both hands are used for medial compression until socket displacement ceases. C, The ideal amount of displacement is 0.5 inch (1.27 cm) from the starting point. If the displacement is greater than 0.5 inch (1.27 cm), the transfemoral socket likely will be unstable for the user in the coronal plane during single-limb support.

The medial displacement test is per- Transverse Plane rotations during early stance. If either formed with medial, simultaneous com- Transverse stability, observed in the the muscle or the underlying connective pression of the proximolateral aspect of swing and early stance phases of gait, tissues are found to be inadequate, the the socket and the greater trochanter also is dependent on both the level individual will not be able to voluntari- of the contralateral limb. Medial sock- of the individual’s voluntary control ly control these forces, and the socket et displacement of more than 0.5 inch and the optimal fi t of the transfemo- may rotate on the limb. In such cases, (1.27 cm) may suggest that either the ral socket. During the evaluation of either targeted socket modifi cations or mediolateral dimension of the trans- the residual limb, the strength of its external components are needed to aid femoral socket or its overall volume is subcutaneous tissue and musculature in controlling transverse rotation. too large. Alternatively, the prosthesis should be assessed to help determine If the individual has adequate vol- user may not possess enough volun- if the individual can control the nor- untary control but still demonstrates tary control to resist the lateral forces mal transverse plane motions of gait, whip-type gait deviations or excessive created during single-limb support40-43 including internal rotational motions socket rotation, these problems may be (Figure 2). during the swing phase and external caused by a suboptimal socket fi t, with

Table 1 Transfemoral Socket Construction

Primary Socket Construction Construction Example Primary Indication Major Advantages Chief Limitations Hard socket Mature limbs Simple design Comfort with rigid proximal (Integrated rigid inner Firm limbs Durability trim lines socket and outer Situations that allow Easy to clean Hard surface when sitting frame) for reduced trim line Solid construction that Adhered tissue, invagi- height will not alter over time nations or sensitive bony Minimal wall thickness areas may not be accom- modated

Removable fl exible Any limb shape Adjustable Inner socket may change inner socket; rigid Flexibility in design Allows for dynamic shape over time outer frame Dynamic muscle muscle movement and Durability (Flexible inner socket movement relief for sensitive tissue can be removed from Relief areas for sensitive while maintaining a outer frame) tissue total contact fi t Proximal soft-tissue Comfort in sitting support Fenestrations can be created while retaining socket strength

Emerging Socket Construction Removable, fl exible Volume fl uctuations Dynamically alters inner Lengthy fabrication process inner socket; rigid Progressive pressure in socket shape and com- More maintenance outer frame; dynamic specifi c areas pression felt on limb in panels User adjustability specifi c areas (Panels are adjustable Compression from panels to change compres- is user adjustable sion on inner fl exible socket)

Flexible socket; embed- Mature limbs Flexible interface Lengthy fabrication process ded rigid frame High levels of voluntary Soft proximal brim Fragile (Rigid frame is laminated control Comfort in sitting Limited adjustability between layers of Dynamic muscle move- Soft outer surface Heavier than other construc- fl exible material) ment Rigid embedded frame tion types supports socket with minimal surface area

volumetric incongruences exerting the general classifi cations of socket con- prosthesis user’s limb, a hard socket is largest infl uence on rotational control. struction for transfemoral prostheses. a single-walled, static socket that is de- To reduce transverse rotation, socket fi t The fl exible inner socket has two vari- signed to be in direct contact with either must be optimized to match the individ- ations that are gaining in popularity: the user’s skin or an interface such as a ual’s limb volume or accommodations the fl exible inner socket with dynamic roll-on gel liner or prosthetic sock. The must be made for muscle contractions. panels and the fl exible socket with an advantages of a hard socket include its embedded rigid frame (Table 1). simplicity, thin-walled construction, du- Primary Socket Designs rability, and ability to be easily cleaned Socket Construction Hard Sockets and maintained. Because this socket The hard socket and the fl exible inner Although all sockets are construct- option offers little padding and can- socket with a rigid frame are the two ed around a positive model of the not absorb the shear forces generated

between the limb and the socket walls, residual musculature to expand during construction option has been success- it is intended for limbs with stable vol- ambulation. Even with the frame cut fully used in upper limb prosthetic ap- ume, fi rm tissue, and fair to good skin away, the inner fl exible socket contains plications and is now beginning to be sensation. This socket construction is the soft tissue and maintains the bene- used with transfemoral prostheses.44 generally contraindicated in individuals fi ts of hydrostatic weight bearing. In the The major advantages of this socket with adhered scar tissue, invaginations, absence of the inner fl exible socket, such construction include its overall fl exi- and sensitive bony prominences; these fenestrations would allow the individu- bility, reported comfort, minimal trim prosthesis users require a more forgiving al’s skin to protrude from the openings, lines, and perceived improved control of design.33 compromising both hydrostatic loading the prosthesis.45 Although this socket is A transfemoral hard socket is typi- and pressure distribution during weight heavier, more diffi cult to fabricate, and cally fabricated from a carbon fi ber or bearing and leading to localized window less durable than other types of sockets, a rigid thermoplastic material with no edema and skin breakdown. the fi nal product offers a very fl exible fenestrations or cutouts. This socket One variation of a fl exible inner sock- system with confi ned, rigid support. construction does not readily allow for et with a rigid outer frame uses dynamic fl uctuations in residual limb size, so an panels that can be adjusted to help regu- Socket Designs optimal initial fi t is crucial. Similarly, late pressures within the socket. In this The two primary socket designs for the prosthesis user with a hard socket variation, instead of using open cutouts, transfemoral prostheses are the ischial must be diligent in volume management the outer rigid frame is fabricated with ramal containment and the subischial to maintain a total contact fi t. free-fl oating panels that are connected designs. Two subcategories of the ischial by tensioning cords. In the fabrication ramal containment design are the is- Flexible Inner Sockets process, hollow tubes are laminated into chial containment (IC) and the ramal The second type of socket construction the frame in strategic locations. After containment (RC) designs. Variations incorporates a fl exible inner socket ca- the panels are cut out of the frame, the of the subischial design include the pable of elastic movements and a rigid hollow tubes are exposed, allowing quadrilateral design and those designs outer frame for stability. This design can tensioning cords to be fed through the that may incorporate the use of subat- be in direct contact with user’s skin or tubes in both the panels and the rigid mospheric-assisted vacuum suspension an interface such as a roll-on gel lin- frame. The cords can be tightened as (Table 2). er or a prosthetic sock. The main ad- needed to move the panels closer to the vantage of this design is that the inner inner fl exible socket, thereby increas- Ischial Containment Designs fl exible socket, which is made from a ing the overall compression felt by the In current practice, the IC socket is the silicone-based thermoplastic material, user. The main advantage of this system most commonly used design, with nu- allows for both volumetric and local- is the ability of the user to change the merous iterations in both teaching and ized fi tting accommodations. In addi- shape and volume of the socket. When clinical practice. All variations of the IC tion, when the proximal trim lines of the necessary, the dynamic panels can be socket have the common goal of provid- rigid frame are lowered, the fl exibility loosened to allow bulbous limbs to enter ing mediolateral stability in single-limb of the proximal inner socket dramati- the socket, and then compressed to cre- support. This goal is achieved by using cally increases the user’s comfort. The ate a total contact fi t. The panels also can an intimately fi tted socket with a narrow brim of the inner socket contains the be adjusted on an activity-specifi c basis, mediolateral dimension while encasing proximal tissue, but it allows for elastic such as relieving tension while sitting the medial aspect of the ischial tuber- movement around sensitive bony areas or kneeling or increasing compression osity and ramus within the socket.30 such as the ischial tuberosity, the as- for strenuous activities such as running. Most IC design variations use hydro- cending pubic ramus, and the anterior An alternative design is a fl exible static weight bearing rather than direct superior iliac spine while sitting. The socket with an embedded rigid frame. ischial weight bearing. In contrast to the fl exible inner socket also allows for in- This design is the result of advances in quadrilateral socket, the medial IC wall creased proprioceptive feedback when materials and fabrication techniques. is angled to match the ischial ramus an- the rigid outer frame is cut away in Similar to prosthetic systems popular gle of the prosthesis user rather than the strategic areas. When the rigid frame is before World War II in which a met- line of progression. The IC socket can fenestrated, the compliant material of al frame was housed within a fl exible help minimize the lateral thrust of the the inner fl exible socket is exposed to leather socket,8 this modern variation socket during single-limb support by allow an individual to feel the surface he uses rigid frames laminated within an buttressing against bony aspects of the or she is sitting on or to have room for otherwise fl exible socket. This socket pelvis. If the orientation of the IC wall

Table 2 Transfemoral Socket Designs

Design Example Primary Indication Major Advantages Chief Limitations Ischial containment When enhanced Enhanced coronal sta- Clinical experience coronal stability is bility with support required to create requested from bony structure optimal fi t User presents with Proximal tissue High proximal trim line lower levels of contained inside of May inhibit hip range of voluntary control socket motion Shorter residual limbs Amount of containment can be Ischial/ramal containment adjusted (The ischial-ramal complex Potential for ischial is contained within the weight bearing socket to provide stability Ramal containment Enhanced coronal sta- Enhanced coronal sta- Clinical experience in the coronal plane during bility with minimal bility with support required to create single-limb support) trim lines from bony structure optimal fi t Proximal tissue out- Discomfort unless side of socket optimal fi t around as- Reduced proximal cending ischial ramus trim lines is achieved Enhanced hip range Lengthy fi tting process of motion with maintenance of coronal stability QQuadrilateraluadrilateral Longer residual limbs Ischial weight bearing Clinical experience User presents with required to create higher levels of optimal fi t voluntary control Minimal coronal stability Previous user Narrow anteroposterior dimension Predetermined rectan- gular socket shape

Subischial (The ischium is not contained within the socket. Coronal stability during single-limb Subischial, Longer residual limbs Reduced trim lines Clinical experience support is obtained by vacuum-assisted High voluntary Excellent suspension required to create soft-tissue compression) suspensionsuspension control that may enhance optimal fi t High gadget coronal stability Tissue proximal to the tolerance issues due to inti- brim may be stressed Uses hydrostatic mate fi t Multistage donning weight bearing Amount of assisted process vacuum suspen- May be a bulky design sion force can be regulated Hip range of motion not limited angle does not match the anatomic an- ischium from 1 to 1.75 inches (2.54 Sockets that incorporate more proximal gle of the ischium and ascending ischial to 4.445 cm) proximal to its distal as- degrees of IC typically have more proxi- ramus, the prosthesis user will likely feel pect.29,30,41 This amount of containment mal gluteal containment as well. undo pressure and discomfort with this gives adequate mediolateral control Some IC designs, such as the Marlo socket design. while allowing for tissue around the Anatomical Socket (Ortiz International), The amount of IC is variable, with ischium and ascending ischial ramus suggest that coronal stabilization can be most designs initially containing the to aid in padding the sensitive bone.46 achieved by limiting bony containment

to the ascending ischial ramus and low- femoral support was reported by Long39 Because of the large amount of re- ering the other proximal trim lines of the in the 1980s and led to the initiation of maining compliant soft tissue, general socket.47 This socket design allows great- early IC designs.10,46 residual limb shape, and minimal bony er range of motion about the hip and As the quadrilateral socket has de- femoral anatomy, suspension is often decreases some metabolic costs.18,20,47 clined in popularity, there has been quite diffi cult to achieve for an indi- However, this type of design is diffi cult growing interest in a subischial design vidual using a transfemoral prosthesis. to fi t and may be rejected because of lo- that uses hydrostatic weight bearing as Various forms of suspension have been calized pressures on the medial ramus. does the IC socket but does not incor- attempted to minimize transfemoral Achieving an optimal fi t requires the porate the ischium into the socket. This socket displacement. Although all of prosthetist to have an elevated level of design was introduced in the 1960s by these variations have merit, there is no clinical skills. Redhead.16 Although his work contrib- evidence that supports a clinical stan- Given the proximal intrusions of IC uted to a better understanding of hydro- dard for a single suspension system.33 designs into perineum and bony ele- static weight bearing, the design did not Therefore, it is imperative for the pros- ments of the pelvis, the common chal- achieve widespread acceptance. thetist to have a working knowledge of lenge of IC designs is determining the Current subischial socket designs the various systems available and take amount of actual bony support that can are based on the original concepts de- into consideration the unique goals and be tolerated by the individual user. IC scribed by Redhead,16 but they also in- characteristics of each transfemoral designs tend to work well for individu- corporate a roll-on gel liner interface and prosthesis user. als with shorter residual limbs or those assisted vacuum suspension. These sub- Current suspension systems being who lack voluntary control of their ad- ischial sockets may be preferred over IC used at the transfemoral level are gen- ductor muscles. For individuals with designs because of their lowered proxi- erally classifi ed as subatmospheric, longer residual limbs and high degrees mal trim lines.43,45 In addition, there are negative-pressure, and belt-type sys- of voluntary control, aggressive IC may suggested advantages of increased limb tems. Subatmospheric systems use be unnecessary, and a subischial design health, volume stabilization, reduced some level of negative atmospheric might be more appropriate.19,43,48 perspiration, and increased comfort.49 pressure combined with surface ten- Studies are needed to objectively prove sion to maintain the transfemoral sock- Subischial Designs these suggested advantages for varying et on the residual limb. Subcategories The quadrilateral socket is a subischial limb lengths and levels of voluntary con- of subatmospheric designs include design that uses ischial weight bearing trol, but the design appears to be a viable skin-fi t suction, roll-on liners with on its posterior brim with some degree choice at this time. various locking mechanisms, roll-on of additional hydrostatic loading of the liners with a hypobaric sealing mem- residual limb to support the individu- Suspension Systems brane, and vacuum-assisted suspen- al’s weight.14 The ischium rests on the Total contact socket fi t and adequate sion. Belt-type systems use positive, posteromedial aspect of the socket brim suspension throughout the entire gait superiorly directed forces created by a where it is held in place through antero- cycle is necessary to ensure the confi - strapping system secured around the posterior socket compression. In contrast dent use of a transfemoral prosthesis. pelvis. Subcategories of belt systems to IC socket designs, this anteroposterior During the stance phase of gait, total include the Silesian belt, elastic belt tightness requires an increased medio- contact is maintained by the user’s suspension, and hip joint and pelvic lateral dimension to allow proximal soft weight. During the swing phase, the belt suspension (Table 3). tissue to enter the socket. However, this inertia and weight of the prosthesis will increased mediolateral dimension can displace the socket from the residual Subatmospheric Suspension create a lack of coronal support, leading limb if the suspension system is inad- Subatmospheric suspension provided to pressure on the perineum and com- equate. On taking the next step, the by skin suction or a roll-on gel liner is mon gait deviations such as lateral trunk user will force the limb back into the the most prevalent type of suspension fl exion and a wide base of support. Also socket, creating a piston-type motion. design.33 These systems work by com- common with the quadrilateral design This displacement or pistoning of the bining friction with a negative pressure is diffi culty in achieving adequate lat- limb within the socket, even if it is a few differential within the socket to main- eral support for the femoral shaft, which millimeters, can lead to loss of prosthetic tain suspension of the prosthesis on the often leads to the reduced effectiveness control, skin irritation, overall socket residual limb. In the literature, the term of the gluteus medius to stabilize the pel- discomfort, distal residual limb edema, “suction” is used synonymously with vis in single-limb support. This lack of and gait deviations.11,33 the term “vacuum” when discussing

Table 3 Transfemoral Suspension

Suspension Type Example Primary Major Advantage Chief Limitations Indication Skin-fi t suction Whenever clinically Increased pro- Susceptible to volume feasible prioception changes Mature limb between limb and Diffi cult to don prosthesis Limited absorption of shear and impact forces felt on limb

Roll-on gel liner with pin Firm limb Easy to don Distal distraction can lock, lanyard, or magnet Expect volume Secure suspension lead to edema locking mechanism changes Allows for volume Hand strength and changes dexterity required to Absorption of shear apply liner and impact forces Alignment and build height considerations

Subatmospheric, negative pressure (Primary means of suspension used with Roll-on gel liner with Firm limb Easy to don Hand strength and most transfemoral hypobaric seal dexterity required to prosthetic systems) Expect volume Can allow for volume changes changes apply liner Minimal distal distraction Absorption of shear and impact forces

Roll-on gel liner, Mature limb Excellent suspension Bulky vacuum-assisted Active increases pro- Diffi cult to don suspensionp Minimal socket prioception and Gel liner is fragile control displacement Gadget tolerance needed Minimal socket displacement Maintenance decreases daily trauma to limb

transfemoral suspension systems. A internal pressure of the socket environ- between the gel liner and the socket. The suction system has been deﬁ ned as ment is not actively regulated.50 negative pressure within a socket can be a subclass of subatmospheric socket The suction necessary for these sus- measured with a typical vacuum gauge systems that allows air to be expelled pension systems can be created between in inches of mercury (inHg), where nor- from a sealed socket while preventing air the skin and the hard socket, between mal atmospheric pressure is 0 inHg. In from entering the socket. However, the the skin and a roll-on gel liner, and discussing transfemoral suspension, the

Table 3 ( continued)

Suspension Type Example Primary Major Advantage Chief Limitations Indication Silesiansian Limit socket Firm belt for secure Minimal suspension rotation feel Hand strength and Volume changes Adjustable dexterity to don Auxiliary suspen- Can be removable Pressure around the sion pelvis Diffi cult to clean

Elasticstic suspension Reduce socket Flexible Minimal suspension rotation Adjustable Elastic suspension Belts Volume changes Removable Hand strength and (Typically used as Auxiliary suspen- dexterity to don secondary or auxiliary sion Warm around the pelvis suspension; primary suspension only when Diffi cult to clean negative atmospheric pressure cannot be used)

Hip joint and pelvic belt Short residual limbs Maximum coronal Belt may be uncomfort- Weak hip abductors support able Low levels of volun- Migrates when sitting tary control Minimal suspension Diffi cult to clean

larger the negative number the greater The greater the inertial forces generated also creates surface tension along the is the suspension force (−30 inHg rep- in swing, the greater these distractive inner socket walls that further resists resents an absolute vacuum). forces, thus requiring higher negative some of the distraction forces felt during The original transfemoral suction pressures to hold the socket in place. swing. Typically, a one-way expulsion suspension designs were used within valve is located distally on the trans- a skin-fi t socket where the suction was Suction Suspension: Skin-Fit femoral socket that permits air to escape created simply between the skin and Skin-fi t suction suspension has the during weight bearing while preventing the inner socket wall.51 Basic suction benefi t of direct skin contact with the air from entering during swing phase. suspension systems are characterized socket, allowing high levels of pro- For skin-fi t suction suspension systems, as low, negative-pressure systems, with prioceptive feedback to the user. The the internal pressure clinical readings readings in the 0 to −8 inHg range. skin moves with the socket, allowing have been found to be approximately During weight bearing, these systems the user to quickly perceive and react −8 inHg during the swing phase. have a vacuum reading of 0 inHg. to small changes in socket position. The individual generally dons the During ambulation, the vacuum reading Proximal, circumferential socket re- prosthesis by initially applying a don- increases in value through swing phase ductions create a seal against the skin ning sleeve over the residual limb and as the momentum of the advancing limb that prevents air from entering the feeding the loose end of the sleeve and weight of the prosthesis attempt to socket, thereby permitting suction to through the open distal valve hole. distract the prosthesis from the limb. occur during swing phase. The skin The sleeve breaks the surface tension

between the socket and the skin, allow- magnets. The donning of such systems internal socket pressure is 0 inHg, ing the individual to seat the limb inside is generally much quicker compared whereas socket pressure with vacu- the socket while pulling proximal soft with skin-fi t suction suspension sys- um-assisted suspension is less than 0 tissue into the socket.34 The sleeve is tems. In addition, socks can be worn inHg, and it can be as low as −25 inHg. progressively and fully extracted from over the liner to accommodate volume Both systems use an expulsion valve to the socket. With the limb fully seated, changes without a loss of suspension. maintain the pressure differential, with the one-way air valve is installed in Disadvantages of using roll-on liners vacuum-assisted suspension also using place. in a transfemoral prosthesis include a an external mechanism to draw air from The disadvantages of skin-fi t suc- minimum level of hand strength and the socket. Although suction systems tion suspension systems include dif- dexterity for correct donning, the po- have a negative pressure environment fi culties with donning, comparatively tential for tearing the somewhat fragile in swing only, vacuum-assisted systems poor mitigation of shear forces, and liners because of improper handling and have a continual negative pressure en- poor accommodation of residual limb sustained use, and the need for liner vironment through stance and swing. volume fl uctuations. Successful donning replacement if damage occurs. Roll-on Vacuum-assisted suspension has of a skin-fi t suction suspension system liners also require consistently good been slow to gain acceptance in trans- requires strength and balance because hygiene to reduce odor and maintain femoral applications.52 This may be the the soft tissue needs to be pulled into the cleanliness. result of complicated fabrication and socket using a donning sleeve; this may donning processes and diffi culties in be diffi cult for some users to manage. Roll-On Gel Liners: Hypobaric and maintaining a proximal vacuum seal. Scar tissue and invaginations represent Vacuum-Assisted Suspension However, modern material advances, another potential contraindications be- Suction suspension with roll-on liners creative techniques, and design vari- cause shear forces are typically not well can be accomplished by direct contact ations are making vacuum-assisted tolerated by these clinical presentations with the liner against the socket wall suspension a more viable choice for and there is potential for skin break- (similar to skin-fi t suspension) or with transfemoral applications. Anecdotal down if the skin is not well protected the use of hypobaric sealing mem- reports indicate that these systems work and/or padded. Because skin-fi t suction branes. Roll-on liners that use suction well for individuals with longer residual requires the maintenance of a proximal, for suspension tend to have less distal limbs and high voluntary control.49 air-tight seal against the skin, even small distraction and minimized socket ro- The three basic subischial socket changes in limb size caused by a change tation compared with those that use a designs that incorporate vacuum-as- in weight or edema can compromise distal locking mechanism. sisted suspension are the single-wall suspension. As is the case with skin-fi t suction, internal sealing system, the single-wall these roll-on liner systems use negative external sealing system, and the dou- Suction Suspension: Roll-On Gel pressure and surface tension to maintain ble-wall internal sealing system (Ta- Liners and Locking Mechanisms suspension. To fully seat the residual ble 4). Although these three designs Roll-on gel liners, when used as an in- limb and liner into the socket, the sur- each have advantages and limitations, terface, absorb shear and impact forces face tension must be reduced, typically all use a roll-on gel liner as an interface acting on the limb, stabilize soft tissue, with the use of isopropyl alcohol in lieu and utilize the creation of high levels of and accommodate volume fl uctuations. of a donning sleeve. The liner is rolled vacuum-assisted suspension between As with skin-fi t suspension systems, lin- on over the residual limb, alcohol is the liner and the socket rather than the ers are held in place by a combination sprayed on the liner, and the limb and skin. Although skin is compatible with of suction and surface tension and may liner are slipped into the socket and basic suction suspension, it is porous also be used as a means of suspension engage against the inner socket wall and irregular in shape, making it a poor with the attachment of a distal locking as the alcohol quickly evaporates. The surface for maintaining elevated levels mechanism such as a pin, lanyard, or resultant seal maintains the pressure of negative pressure. Gel liners have a magnet. differential within the socket. smooth, fl exible, nonporous surface that To don these systems, the user rolls This variation in roll-on liner use allows for a vacuum seal to be main- on the liner, inserts his or her limb into can be incorporated with either simple tained throughout ambulation, while the socket, and engages a locking mech- suction or vacuum-assisted suspension. sitting, and during participation in ac- anism that is typically embedded in The two suspension methods differ in tivities of daily living. the distal aspect of the socket. Locking the internal socket pressure while stand- All three subischial socket design mechanisms include pins, lanyards, or ing. In simple suction suspension, the systems also use a wick in the form of a

Table 4 Transfemoral Socket Design, Subischial Variations, Vacuum-assisted Suspension

Subischial Variation Example Major Advantages Chief Limitations Subischial, single-wall Reduce bulk when compared Limited area to achieve suspen- system, internal sealing with other subischial sion because of the height of system designs the vacuum seal inside of the (Roll-on gel liner with a hypo- Minimal donning process socket baric seal inside of socket, More proximal trim lines may Shorter residual limbs wick below the seal, enhance coronal stability external vacuum pump)

Subischial, single-wall sys- Suspension over the entire Bulky tem, outer sealing sleeve socket Liner susceptible to tears at brim (Long roll-on gel liner, wick- Reduced trim lines Lengthy donning process ing sock, refl ected liner Option for shorter limbs Exposed liner may adhere to over brim of socket, seal on clothing outside of socket, external vacuum pump)

Subischial, double-wall sys- Inner suspension seal is pro- Bulky tem, sealed internal socket tected by outer frame Lengthy donning process (Roll-on gel liner and wicking More proximal trim lines may Lengthy fabrication and fi tting sock, rigid internal socket enhance coronal stability process affi xed to liner by a sealing Short residual limbs sleeve, internal socket connects to outer frame, external vacuum pump

sock or fabric liner cover. The wick be- This suspension system is simple in formation of holes. It also is bulkier than gins at the distal aspect of the liner and design, fabrication, and donning and the internal sealing system. terminates distal to the vacuum seal, also allows for any variation of prox- The double-wall socket uses an inter- allowing for the transfer of air molecules imal trim lines. Its main limitation is nal socket to create vacuum suspension between the socket and the liner. This the limited surface area over which a and an external socket to provide the facilitates uniform internal socket pres- vacuum seal can be achieved, which can proximal brim and distal attachment of sures between −5 inHg and −25 inHg; be an issue for individuals with shorter the prosthesis. A roll-on liner is donned, typical prosthesis users prefer approxi- residual limbs. followed by a wicking sock. The internal mately −15 inHg. The greater the nega- The single-wall, external sealing de- hard socket, typically half the length of tive pressure, the greater the suspension sign overcomes this issue with the use the residual limb, is then applied over force; however, high vacuum levels may of a longer roll-on liner that is refl ected the liner. A vacuum seal is created when be diffi cult to maintain over time. over the proximal brim and sealed dis- a sealing sleeve is applied over both the The single-wall internal sealing de- tally on the outside of the socket using outer wall of the internal socket and the sign works with a hypobaric seal that is a sealing sleeve. This design requires liner, as is often seen in transtibial sys- either integrated into the roll-on liner or that the proximal trim lines be reduced tems. Negative pressures are drawn be- applied over the liner. A wick is used to allow the liner to be refl ected. Al- tween the liner and the socket through distal to the seal, and air is drawn out of though the system has the benefi t of a one-way expulsion valve. The internal the system either manually with a hand lower trim lines, the exposed liner is socket is then inserted into the exter- pump or actively by with an electronic subject to wear from the environment nal socket where it is affi xed by vari- or integrated weight-activated pump. and is prone to failure because of the ous forms of locking mechanisms. The

major limitations of this design are its The fi rst concern in knee compo- in early stance. If the individual has bulk, weight, and complicated donning nent selection should be stability in limited voluntary control, the prosthet- and fabrication processes. early stance. If the individual has lim- ic foot should reduce the knee fl exion ited voluntary control, the knee unit moment. This can be accomplished with Belt-Type or Auxiliary Suspension must have inherent stability, which a soft heel component in the prosthetic Belt-type suspension offers convenience can be variously achieved through foot itself or by altering the alignment of over performance. These systems are mechanical linkages, breaking mech- the foot relative to the socket. The next easy to don but offer minimal primary anisms, or hydraulic dampening con- concern is the transition from stance suspension. Belt-type suspension sys- trol. Recently, the addition of sensors to swing phase where the foot should tems are primarily used to provide sec- and microprocessor control units has generally enhance late stance stability to ondary or auxiliary suspension and aid demonstrated an increased ability to allow the user to take an adequate step in control of the device. The three main allow safe ambulation, reduced cogni- with the contralateral limb. The length, types of belt-type suspension systems tive dedication to controlling the knee stiffness, and design of the keel, along are the Silesian belt, elastic suspension, unit, increased gait effi ciency, and in- with alternations in alignment will af- and the hip joint and pelvic belt (Ta- creased overall user confi dence with fect stability in this late stance phase. ble 3). Silesian and elastic systems are the prosthesis.53 soft belt systems that can be attached Another concern in knee component Additional Component to the socket to help reduce rotation selection is the ability of the knee to Considerations and provide minimal suspension. For transition from stance to swing phase. With the anatomic knee and foot ab- individuals who ambulate at a minimal The methodology varies by which the sent, users of transfemoral devices are cadence and require a socket system prosthetic knee “knows” when to tran- missing elements of rotation, shock ab- that is both easy to don and allows for sition from stable load bearing in stance sorption, and stance-phase knee fl exion. free movement of air, these suspension phase to less restricted motion that will Additional components of transfemoral systems may be an adequate primary allow swing phase fl exion. Mechanically prostheses can address these missing suspension option. Alternatively, for in- controlled knee units typically rely on a anatomic elements. Positional rotation dividuals who require greater coronal transfer of load or the mechanical knee units allow the prosthesis user to spin stabilization because of a short residual angle to initiate this transition. In con- the prosthetic components distal to an limb or lack of abductor muscle control, trast, microprocessor-controlled knee adaptor. The function of these units is a hip joint and pelvic belt can be used. units use algorithms based on input optimized when they are applied on the This system provides maximal stability received from load sensors, accelerom- distal aspect of the socket and proximal against lateral socket motion but pro- eters, gyroscopes, and joint angles. Be- to the knee. This allows the user to cross vides minimal suspension. cause of this nuanced level of regulation, his or her legs, more easily tie shoes, don microprocessor-controlled knee units pants, and enter the front seat of a car. Component Considerations allow for more controlled prosthetic Torque absorption units can be com- Prosthetic Knee Considerations ambulation, enabling the user to confi - bined with shock absorbers to reduce Because an individual with a transfem- dently address changes in the environ- the shear and impact forces felt on the oral prosthesis has no direct musculo- ment, such as walking down slopes or residual limb. Although these compo- skeletal connection to the prosthetic ramps, movements in confi ned spaces, nents are effective, they add weight, cost, knee or foot, the most optimal compo- descending or ascending stairs, and and spatial considerations to the overall nents must be selected. If the prosthetic walking backward. These situations il- design of the prosthesis. knee unit is to simulate the function of lustrate scenarios in which mechanically Stance fl exion, the 15° to 20° of knee the anatomic knee it must provide sta- controlled knees often fail to provide fl exion necessary for optimized gait, is bility in early stance, allow for shock consistent support and which require achieved during loading response,22 and absorption while maintaining a lowered the prosthesis user to be cognizant of it is often a desired feature when cre- center of mass through midstance, pro- environmental changes. ating transfemoral prosthetic devices. vide stability through terminal stance, However, this amount of knee fl exion allow a smooth transition into swing Prosthetic Foot Considerations in early stance can induce a sensation phase, limit initial swing phase fl exion When selecting a prosthetic foot for an of instability for many individuals with across a range of cadences, advance the individual with a transfemoral amputa- a transfemoral amputation. Prosthet- limb through midswing, and smoothly tion, an initial concern is the infl uence ic stance fl exion is variously obtained decelerate at terminal swing.22 of the foot on the knee fl exion moment through the design of the knee frame,

Figure 3 Illustrations show the process of initial coronal alignment for placement of the prosthetic knee and foot. A, Posterior view of anatomic alignment in the coronal plane. The hip joint aligns over the knee joint and the ankle joint. B, Because the hip joint is diffi cult to represent in transfemoral alignment, the location of the ischium (X) is used instead. For longer residual limbs, the coronal alignment line begins 1 inch (2.54 cm) lateral to the ischium, then continues distally through the posterior bisection of the prosthetic knee and the posterior bisection of the prosthetic foot. C, For shorter residual limbs or individuals with lower levels of voluntary control, the coronal alignment line is shifted laterally, closer to the bisection of the prosthetic socket, but never more lateral than the bisection of the socket. D, A completed transfemoral alignment with the socket set at the initial adduction angle (heavy black line) and the connecting pylons attached to the socket, knee, and foot.

compressive bumpers, and hydraulic hip fl exion, adduction attitude, and progression and the necessity to mini- cylinders. transverse limb orientation. The sock- mize transverse plane gait deviations. et is generally set in a fl exion angle 5° This orientation is especially important Alignment Considerations greater than the individual’s maximum for proper fi tting of IC sockets. The principles of transfemoral prosthe- hip extension. This added hip fl exion With the socket in the proper ori- sis alignment have altered little over permits the user to take an adequate step entation, the focus is on the place- time. In 1955 Radcliffe14 addressed with the contralateral limb and puts a ment of the prosthetic knee and foot. transfemoral alignment considerations mild stretch on the hip extensor mus- In able-bodied individuals, coronal in his statement that the artifi cial limb cles to allow them to be more effi cient alignment of the hip joint is typically “… must provide both adequate sup- in early stance.14,29,30,37,40 directly over the knee and ankle joints port and a natural-appearing gait with The transfemoral socket is also set (Figure 3, A). For initial bench align- as modest consumption of energy as to match the individual’s recorded ment of the transfemoral prosthesis, the possible.” These standards have not adduction orientation. This will align actual hip joint cannot be used as a ref- appreciably changed. Prosthetists at- the femur under the hip joint and put erence point because it cannot be locat- tempt to create a stable and effective a mild stretch on the gluteus medius, ed on the prosthetic socket. However, transfemoral gait pattern with proper increasing effi ciency during single-limb locating a point on the socket brim that socket fi t; effective suspension; and support.54 Setting the proper amount of is 1 inch (2.54 cm) lateral to the location diligence in bench, static, and dynamic socket adduction also reduces the ten- of the ischium will provide a reasonable alignments. dency for proximal lateral gapping of the approximation. The prosthetic knee and Before it is fi tted to a patient, the socket and helps to maintain a narrow ankle joints are placed directly below prosthesis is set up in bench align- base of support.29,40 Transverse orienta- this identifi ed point. The initial coronal ment, which refl ects the individual’s tion is determined by the user’s line of bench alignment allows for stability in

Figure 4 Illustrations show the process of initial sagittal alignment of the prosthetic trochanter-knee-ankle. A, Lateral view of anatomic alignment in the sagittal plane. The hip joint is placed over the knee joint and over the ankle joint. B, The trochanter-ankle reference line. t = the approximation of the position of the anatomic hip joint center. This point can be reasonably estimated by bisecting the socket, but it does not necessarily represent the anatomic placement of the trochanter. a = ankle joint or the functioning position of the ankle joint recommended by the manufacturer for the selected prosthetic foot. C, The location of the prosthetic knee joint center (k) is shown in alignment with the trochanter-ankle line. D, The knee center of the prosthetic knee has been moved posterior (arrow) to the trochanter-ankle line to achieve a more stable alignment. This is considered a voluntary alignment. E, The knee center of the prosthetic knee now positioned anterior (arrow) to the trochanter-ankle line creates a more unstable alignment. This is considered an involuntary alignment. F, A completed transfemoral alignment is shown with the initial socket fl exion angle (black line) and the connecting pylons from the socket to the knee to the foot. double-limb stance, induces a modest placed more laterally under the socket expenditure by inducing a wider base lateral thrust in single-limb stance, for shorter residual limbs or in individu- of support. and achieves a narrow 2-inch (5.08- als with compromised voluntary control In able-bodied individuals, the sagit- cm) base of support (Figure 3, B). The (Figure 3, C). However, this necessary tal plane alignment of the ground reac- prosthetic knee and ankle should be accommodation will increase energy tive force is posterior to the hip joint and

anterior to the knee and ankle (Figure 4, has to voluntarily control the sagittal advancing the limb are practiced in a A). This anatomic alignment allows the stability of the knee. This alignment is safe environment (such as with parallel prosthesis user to stand with minimal also seen with knee units possessing bar support before ambulation). During energy expenditure. Because the ana- inherent stability because it facilitates dynamic alignment, the prosthetist will tomic hip joint cannot be used as a point early stance flexion and permits easier work to optimize gait and minimize of reference on the prosthetic socket, the initiation of swing phase knee flexion energy expenditure by making incre- apex of the greater trochanter is used. in late stance (Figure 4, E). If the knee mental changes to the alignment and For bench sagittal plane alignment, a center point is directly on the trochan- working with a therapist to focus on simulated reference line is used to create ter-ankle line, it is considered to be on enhancing muscle strength and range a stable prosthetic alignment. This line “trigger,” where the system may be in of motion. is called the trochanter-knee-ankle line. voluntary or involuntary alignment de- To understand the use of the trochan- pending on the placement of the pros- Summary ter-knee-ankle reference line, a single thetic foot with each step (Figure 4, F). Great technological advances have been axis knee and single axis foot will be as- In the transverse plane, the pros- made in transfemoral prosthetic sockets, sumed, because these components have thetic knee is externally rotated 5° to components, and suspension systems in very little inherent stability and require compensate for the natural 5° of internal recent years. However, it must be un- that the stability of the overall prosthetic socket rotation that will occur during derstood that there is no single socket system be derived by the alignment of swing phase. This rotation ensures that design, alignment, or prosthetic system the socket relative to the knee and ankle the knee will flex in the line of progres- that will be optimal for all individuals components. sion during swing. For individuals who with transfemoral amputation. There is The trochanter-knee-ankle line be- walk faster, the amount of internal ro- a need for prosthetists to continually de- gins by determining a reference point tation will increase, and the initial ex- velop their clinical and technical skills for the trochanter and approximating ternal knee rotation should be larger. to provide the most appropriate device the position of the hip joint. This point When bench alignment is complete, and the best fit for each patient. can be reasonably estimated by bisect- the prosthesis is donned and static or The team must address issues of en- ing the socket in the sagittal plane at standing alignment is assessed. The foot ergy expenditure, body image, levels its most proximal aspect (Figure 4, B). should be flat on the floor with 2 to 4 of voluntary control, and socket fit in This is followed by the placement of the inches (5.08 to 10.16 cm) of base sup- creating the treatment plan, and they prosthetic ankle joint, a reference point port. The knee should be extended and should have an intimate knowledge of that differs for every prosthetic foot and safe with socket flexion, with adduction appropriate sockets designs, suspension is identified within individual manufac- and rotation matching the individual’s systems, components, and alignment turer’s guidelines. When the trochan- limb orientation. Generally, if bench considerations. Clinical experience, ter and prosthetic and ankle reference alignment conditions were observed, knowledge of evolving clinical stan- points are vertically aligned (Figure 4, minimal adjustments will need to be dards, the use of available evidence, B), the prosthetic knee is set at its prop- made to achieve a proper static fit. Any and the incorporation of appropriate er height and located according to the accommodative changes in flexion or outcome measures also will assist the manufacturer’s recommendation for the adduction will change the position of rehabilitation team in providing optimal knee center’s sagittal reference point. the socket over the knee and foot, which care to their patients. This point may be posterior, through, will alter the stability of the system. In or anterior to the trochanter-ankle line such instances, the proper trochan- References (Figure 4, C). Placing knee center poste- ter-knee-ankle alignment should be . 1 Ziegler-Graham K, MacKenzie EJ, rior to the line creates a safe alignment, reestablished before ambulation begins. Ephraim PL, Travison TG, Brook- because the individual’s weight and the Because every prosthetic knee and meyer R: Estimating the prevalence ground reaction force keep the knee foot has different triggers to transition of limb loss in the United States: locked in extension. This also can be from stance to swing control, the pros- 2005 to 2050. Arch Phys Med Rehabil described as an involuntary alignment, thesis user must be made aware of how 2008;89(3):422-429. Medline DOI because no voluntary control is required each component functions before am- 2. Belatti DA, Phisitkul P: Declines in to keep the knee in extension (Figure 4, bulation is attempted. The prosthesis lower extremity amputation in the D). In contrast, placing knee center ante- user should be observed and instructed US Medicare population, 2000-2010. rior to the trochanter-ankle line creates on proper techniques while functions an alignment in which the individual such as sitting, bending the knee, and

Foot Ankle Int 2013;34(7):923-931. socket variants. J Prosthet Orthot 21. Highsmith MJ, Schulz BW, Hart- Medline DOI 1988;1(1):50-67. DOI Hughes S, et al: Differences in the 3. National Center for Health Statistics: 11. Gholizadeh H, Abu Osman NA, spatiotemporal parameters of trans- Health, United States, 2004, With Eshraghi A, Ali S: Transfemoral tibial and transfemoral amputee gait. Chartbook on Trends in the Health of prosthesis suspension systems: A sys- J Prosthet Orthot 2010;22:26-30. DOI Americans. Hyattsville, Maryland, tematic review of the literature. Am 22. Perry J: Gait Analysis: Normal and 2004. Available at: http://www.cdc. J Phys Med Rehabil 2014;93(9):809- Pathological Function. Thorofare, NJ, gov/nchs/data/hus/hus04.pdf. Ac- 823. Medline DOI SLACK, 2010. cessed May 1, 2015. 12. Palmar BF, inventor. Artificial leg. US 23. Deans SA, McFadyen AK, Rowe 4. Esquenazi A: Amputation rehabilita- patent 4834. November 4, 1846. PJ: Physical activity and quality of tion and prosthetic restoration: From 13. Anderson MH: Professional edu- life: A study of a lower-limb ampu- surgery to community reintegration. cation: A nine-year report. Orthop tee population. Prosthet Orthot Int Disabil Rehabil 2004;26(14-15):831- Prosthet Appl J 1961:123-135. 2008;32(2):186-200. Medline DOI 836. Medline DOI 14. Radcliffe CW: Functional consider- 24. Horgan O, MacLachlan M: Psy- 5. Dillingham TR, Pezzin LE, Mac ations in the fitting of above-knee chosocial adjustment to lower-limb Kenzie EJ: Limb amputation and limb prostheses. Artif Limbs 1955;2(1):35- amputation: A review. Disabil deficiency: Epidemiology and recent 60. Medline Rehabil 2004;26(14-15):837-850. trends in the United States. South Medline DOI Med J 2002;95(8):875-883. Medline 15. Anderson MH, Sollars RE: Manual of Above-Knee Prosthetics for Prosthe- 25. Schoppen T, Boonstra A, Groothoff 6. Dodson A, El-Gamil A, Shimer M, tists. Los Angeles, CA, UCLA Pros- JW, de Vries J, Göeken LN, Eisma DaVanzo J: Retrospective Cohort thetics Education Program, 1956. WH: Physical, mental, and social Study of the Economic Value of Or- predictors of functional outcome in thotic and Prosthetic Services Among 16. Redhead RG: Total surface bearing unilateral lower-limb amputees. Arch Medicare Beneficiaries: Final Report. self suspending above-knee sockets. Phys Med Rehabil 2003;84(6):803-811. Vienna, VA, Dobson DaVanzo & As- Prosthet Orthot Int 1979;3(3):126-136. Medline DOI Medline sociates, 2013, pp. 20-24. Available at: 26. Gallagher P, Horgan O, Franchignoni http://www.amputee-coalition.org/ 17. Lusardi MM, Jorge M, Nielsen CC: F, Giordano A, MacLachlan M: Body content/documents/dobson-davan- Orthotics and Prosthetics in Rehabil- image in people with lower-limb zo-report.pdf. Accessed May 1, 2015. itation. St. Louis, MO, Elsevier, 2013, amputation: A Rasch analysis of the 7. Practice Analysis of Certified Practi- pp 652-678. Amputee Body Image Scale. Am tioners in the Disciplines of Orthotics 18. Klotz R, Colobert B, Botino M, J Phys Med Rehabil 2007;86(3):205- and Prosthetics. Alexandria, VA, Permentiers I: Influence of different 215. Medline DOI American Board for Certification in types of sockets on the range of mo- 27. Ephraim PL, MacKenzie EJ, Wege- Orthotics, Prosthetics & Pedorthics, tion of the hip joint by the transfem- ner ST, Dillingham TR, Pezzin LE: 2015, p 37. Available at: http://www. oral amputee. Ann Phys Rehabil Med Environmental barriers experienced abcop.org/individual-certification/ 2011;54(7):399-410. Medline DOI by amputees: The Craig Hospital Documents/ABC%20Practice%20 19. Gailey RS, Lawrence D, Burditt C, inventory of environmental factors. Analysis%20of%20the%20Disci- Spyropoulos P, Newell C, Nash MS: Short form. Arch Phys Med Rehabil pline%20of%20Orthotics%20and%20 The CAT-CAM socket and quadrilat- 2006;87(3):328-333. Medline DOI Prosthetics.pdf. Accessed July 13, eral socket: A comparison of energy 2015. 28. Pezzin LE, Dillingham TR, Macken- cost during ambulation. Prosthet zie EJ, Ephraim P, Rossbach P: Use 8. Marks AA: A Treatise on Artificial Orthot Int 1993;17(2):95-100. Medline and satisfaction with prosthetic limb Limbs With Rubber Hands and Feet. 20. Chin T, Oyabu H, Maeda Y, Takase devices and related services. Arch New York, NY, AA Marks, 1901. I, Machida K: Energy consump- Phys Med Rehabil 2004;85(5):723-729. 9. Canty TJ, Ware RM: Suction socket tion during prosthetic walking and Medline DOI for above knee prosthesis. U S Nav wheelchair locomotion by elderly hip 29. Staats TB: Ischial Containment Sock- Med Bull 1949;49(2):216-233. Medline disarticulation amputees. Am J Phys et Design: Above Knee Amputation 10. Pritham CH: Workshop on teach- Med Rehabil 2009;88(5):399-403. Prosthesis. Master Model Modifica- ing materials for above-knee Medline DOI tion Manual. Carson, CA, California State University Dominguez Hills

Orthotics and Prosthetics Program, prosthesis. Clin Prosthet Orthot Marlo Anatomical Socket and Ischial 2002. 1985;9(4):9-14. Containment Socket. Gait Posture 30. Hoyt C, Littig D, Lundt J, Staats 40. Muller MD: Transfemoral Ischial 2011;34(2):270-274. Medline DOI TB: The UCLA CAT-CAM Above Containment (IC) Laboratory Manu- 48. Strachan E, Davis A, Wontorcik L: Knee Socket, ed 3. Los Angeles, CA, al. Carson, CA, California State Uni- Stride-to-stride temporal-spatial University California Los Angeles versity Dominguez Hills Orthotics gait variability and vacuum pressure Prosthetics Education and Research and Prosthetics Program, 2013. deviation of trans-femoral ampu- Program, 1987. 41. Neumann ES, Wong JS, Drollinger tees ambulating with sub-ischial 31. Kamali M, Karimi MT, Eshraghi A, RL: Concepts of pressure in an ischial prostheses. 2011. Available at: http:// Omar H: Influential factors in stabili- containment socket: Measurement. www.oandp.org/publications/ ty of lower-limb amputees. Am J Phys J Prosthet Orthot 2005;17:2-11. DOI jop/2011/2011-07.pdf. Accessed May 1, 2015. Med Rehabil 2013;92(12):1110-1118. 42. Dillon M: Ischial Containment Socket Medline DOI for Transfemoral Amputees: A Manu- 49. Kahle JT, Orriola JJ, Johnston W, 32. Staat T, Lundt J: The UCLA Total al for Assessment, Casting, Modifica- Highsmith M: The effects of vacu- Surface Bearing Suction Below-Knee tion and Fitting. Bundoora, Australia, um-assisted suspension on residual Prosthesis. Clin Prosthet Orthot National Çentre for Prosthetics and limb physiology, wound healing, and 1987;11(3):118-138. Orthotics La Trobe University, 2006. function: A systematic review. Tech- nol Innov 2014;15(4):333-341. DOI 33. Highsmith JT, Highsmith MJ: Com- 43. Kahle JT, Highsmith MJ: Transfem- mon skin pathologies in LE pros- oral sockets with vacuum-assisted 50. American Academy of Orthotist and thesis users: Review article. JAAPA suspension comparison of hip Prosthetist Lower Limb Prosthetic 2007;20(11): 33-36, 47. Medline kinematics, socket position, contact Society Sub-Atmospheric Tech- nology Group: Definition of terms. 34. Pasquina PF, Cooper RA, eds: Care pressure, and preference: Ischial containment versus brimless. J Re- Available at: http://aaop-llps.ning. of the Combat Amputee. Washington, com/group/SATG/page/defini- DC, Office of the Surgeon General, habil Res Dev 2013;50(9):1241-1252. Medline DOI tion-of-terms-sub-atmospheric-tech- Borden Institute, 2009, pp 553-580. nology. Accessed August 1, 2014. 35. Siriwardena GJ, Bertrand PV: 44. Moran CW: Revolutionizing prosthetics 2009 modular prosthetic 51. Haddan CC, Thomas A: Status of Factors influencing rehabilitation of the above-knee suction socket in the arteriosclerotic lower limb amputees. limb-body interface: Overview of the prosthetic socket development. United States. Artif Limbs 1954;12:29- J Rehabil Res Dev 1991;28(3):35-44. 39. Medline Medline DOI Available at: http://techdigest.jhuapl. edu/TD/td3003/30_3-Moran.pdf. 52. Patterson S: Editorial: Experiences 36. Munin MC, Espejo-De Guzman MC, Accessed May 1, 2015. with negative-pressure socket design. Boninger ML, Fitzgerald SG, Penrod Academy Today 2007;3(3):10-14. LE, Singh J: Predictive factors for 45. Fatone S, Caldwell R, Major M, et al: successful early prosthetic ambula- Development of sub-ischial pros- 53. Highsmith MJ, Kahle JT, Bongiorni tion among lower-limb amputees. thetic sockets with vacuum-assisted DR, Sutton BS, Groer S, Kaufman J Rehabil Res Dev 2001;38(4):379-384. suspension for highly active persons KR: Safety, energy efficiency, and cost Medline with transfemoral amputations. efficacy of the C-Leg for transfemoral 2013. Available at: http://www.nupoc. amputees: A review of the literature. 37. Radcliffe CW: The Knud Jansen northwestern.edu/research/projects/ Prosthet Orthot Int 2010;34(4):362- lecture: Above-knee prosthetics. lowerlimb/dev_subischial.html. 377. Medline DOI Prosthet Orthot Int 1977;1(3):146-160. Accessed May 1, 2015. Medline 54. Gottschalk FA, Kourosh S, Stills 46. Sabolich J: Contoured adducted M, et al: Does socket configuration 38. Practice Analysis of Certified Practi- trochanteric-controlled alignment influence the position of the femur in tioners in the Disciplines of Orthotics method (CAT-CAM): Introduction above-knee amputation? J Prosthet and Prosthetics. A lexandria, VA, and basic principles. Clin Prosthet Orthot 1989;2:94-102. DOI American Board for Certification in Orthot 1985;9:15-26. Orthotics, Prosthetics & Pedorthics, 2000, p 45. 47. Traballesi M, Delussu AS, Averna T, Pellegrini R, Paradisi F, Brunelli S: 39. Long IA: Normal shape-normal Energy cost of walking in transfem- alignment (NSNA) above knee oral amputees: Comparison between