Fracture of the Long Bones

2 Kenneth D Newman1, DVM, MS, DACVS; David E Anderson , DVM, MS, Diplomate ACVS 1Private practice, Ontario, Canada 2Professor and Head, Agricultural Practices, Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, Phone 785-532-5700, Fax 785-532-4989, email [email protected]

Fracture management in alpacas and llamas pres­ ing on the fixation method that is ultimately chosen ents a unique and interesting challenge to the veterinary to provide the best option. Sedation, using xylazine surgeon. The increasing popularity of camelids in North hydrochloride (alpacas 0.3 mg/kg IV, llamas 0.2 mg/kg America means veterinarians are more likely to see them IV), can facilitate patient positioning during radiographs as patients; therefore, dealing with camelid fractures is and therefore prevent further soft tissue damage and quickly becoming part of the normal caseload. Because result in better quality radiographs. Though xylazine is of the relatively high commercial value of most camelids, reported to be contraindicated in pregnant animals since clients will usually be willing to pursue treatment. it may precipitate early parturition during the third Camelids are considered to be excellent patients trimester, the authors have not observed any pregnancy for the treatment of orthopedic injuries because of their complications associated with the use ofxylazine. In the relative low body weight, their ability to ambulate on event of insufficient sedation achieved using xylazine three legs postoperatively, and tolerate external coap­ alone, butorphanol tartrate (0.05 mg/kg IV or 0.1 IM/SQ) tation devices and prolonged periods of recumbency for can be added to provide greater analgesia. recuperation after surgery. 27 For these reasons, the vet­ erinary surgeon has a full repertoire of repair techniques Patient Care During Recovery from Fracture available to choose from when determining the ideal repair option. Not surprisingly, the scientific literature Postoperative management has lagged behind the relatively rapid rise in camelid Postoperative management plays a crucial role 0 popularity; there are currently 62 case reports on ca­ in the success of fracture healing, and cannot be em­ "d 1 7 12 17 19 23 ('[) melid long bone fracture fixation. , - , , - This paper phasized enough. Though the surgery may have been ~ ~ will review the published literature on the management successful, improper management of the patient postop­ (') (') of long bone fractures. Fracture management includes eratively can lead to frustrating complications: implant ('[) en the preoperative, intraoperative and postoperative failure, re-fractures, cast sores, and nerve damage have en time periods. Emergency treatment, clinical workup, been reported in the literature. Fortunately, we have 8-:r:n principles of fracture repair, treatment, and prognosis observed these complications rarely. Regardless, a sec­ q- for specific long bone fractures and their complications ond repair attempt increases expenses and potential for [ will be discussed. complications, therefore decreasing the likelihood for a o· successful outcome. p Diagnosis The type and duration of antibiotic therapy is de­ The hallmark clinical sign of a limb fracture is a termined on a case-by-case basis. Open fractures, the non-weight-bearing lameness; however, other differen­ greater degree of soft tissue damage and fracture com­ tial diagnoses need also be considered. 9 Other clinical minution typically require longer periods of antibiotic signs include swelling, pain, and crepitation at the therapy, compared to simple closed fractures. Postopera­ fracture. In the author's experience, fractures involv­ tive analgesia is predominantly provided by using non­ ing the femoral head tend to be more subtle, since some steroidal anti-inflammatories (NSAIDs) such as flunixin weight bearing is possible. The neurovascular supply meglumine, phenylbutazone, and etodolac (Etogesic®). to the distal limb must be assessed prior to surgery to The use ofNSAIDs is not without some risks, including critically evaluate for neural or vascular compromise. gastrointestinal ulceration (ie: C3), delayed bone heal­ Compromise to these structures can have a significant ing, and kidney failure. The prolonged use of NSAIDs impact on the success of any fracture repair and may should be under veterinary guidance. The cardinal signs change the treatment options. Good quality radiographs of adverse effects include inappetence, oral ulceration, of at least two orthogonal views are required to properly and edema formation. Opioids, such as butorphanol or access the configuration of the fracture in order to deter­ fentanyl transdermal patches, may be used to provide mine repair options. Proper patient positioning and a more potent analgesia during the immediate postopera­ good technique chart are fundamental in producing good tive period in selected cases. quality radiographs. Open or closed fractures, hairline The length of hospitalization varies on a case-by­ or non-displaced fractures, the degree of comminution, case basis. Depending on the fracture configuration and or joint surface involvement will have a significant bear- the inherent strength of the repair method, a couple

108 THE AABP PROCEEDINGS-VOL. 42 of days hospitalization may be all that is required. union. Usually, two additional weeks of stall rest is Postoperative transportation represents an additional recommended after clinical union has occurred before (Q) challenge that requires additional planning and careful the patient may safely reintegrate with the herd. n thought. Though most patients may lie down during 0 "'O transportation, they should be transported in a separate Complications '-< ...... '"i compartment away from direct contact with herd mates. The perceived incidence of morbidity and mortal­ (JQ There are some situations when prolonged hospitaliza­ ity associated with camelid fractures is now believed to g tion is required until sufficient callus has formed, or to be higher than what previously published case reports > 17 22 8 allow intensive wound management for open fractures. have suggested. • Possible explanations for this ap­ (D ...... '"i The disadvantages of prolonged hospitalization include parent increased incidence include the reporting of more (") increased costs and patient stress. Stress associated subtle complications combined with long-term follow-up, § with the initial injury and prolonged hospitalization in a the attempted repair of more complicated fractures by >00 00 strange environment may predispose the development of surgeons, and case report bias. Similar to other spe­ 0 complications, including inappetence (ie: stall sickness) cies, complications of fracture repair include malunion, (")...... and gastric ulceration. The use of NSAIDs can com­ delayed union, non-union, osteomyelitis, implant failure, a...... 7 17 20 22 26 0 pound the risks of these complications developing. The sequestrum formation, and disuse osteopenia. , , - , ~ 0 oral administration of omeprazole may help reduce the Unlike in other species, soft tissue complications also 1-i; formation of gastric ulcers; however, the efficacy of oral include chronic lameness, hyperextension, osteoarthritis, to 0 omeprazole in camelids has recently been questioned. 28 and were more common than implant failure.22 If the < 5· A quiet, docile companion during hospitalization may patient suddenly stops using the affected limb, or there (D help prevent the development of stall sickness, improve is a sudden change in appearance, swelling, and pain ~ ~ appetite, and may even reduce stress. tolerance, veterinary attention is immediately required, (") ,-+-...... The patient's activity after surgery and throughout since these signs indicate complications. The incidence of ,-+-...... the convalescent period must be restricted. A small, dry, complications was not affected by the fixation method.1 0 ~ (D well bedded and ventilated stall that is protected from the Open fractures are more likely to have complica­ '"i elements is ideal. Limited outside access is permitted, tions such as osteomyelitis, compared to closed frac­ 00 0 provided it is dry and the area small. The affected limb tures. 22 Non-union due to the presence of osteomyelitis "'O (D should be inspected daily for use, warmth, signs of swell­ is a frustrating and expensive complication. Successful ~ ing, and surgical site infection. If the patient suddenly management requires rigid stabilization, and often f:; (") stops using the affected limb, or there is a sudden change requires a second surgery to debride and to place an (D 00 21 22 00 in appearance, swelling, or pain tolerance, veterinary autogenous cancellous bone graft. , Typically these 0...... attention is required, since these signs indicate compli­ cases also require prolonged parenteral antibiotics. 00 ,-+- cations. Bandages, when used, need to be kept dry; wet Culture and antimicrobial sensitivity testing may be '"i ~ bandages can cause severe skin irritation and infection. useful for determining antibiotic therapy. Antibiotic­ ~...... Bandages can get wet less obviously by wicking moisture impregnated polymethylmethacrylate (PMMA) beads 0 p directly from the ground. Ideally, bandage changes can placed adjacent to the site of infection may be useful, be done on the farm by the client. On rare occasions, based on the author's clinical impressions. the referring veterinarian may need to facilitate bandage On occasions when the fractured limb is unable changes, especially if sedation is required. to be repaired, amputation may become a viable option The timing and frequency of follow-up visits is de­ and is well tolerated by camelids in our experience and termined on a case-by-case basis. Follow-up visits are others. 27 Camelids tend to be amenable to prosthetic important since they allow assessment of the healing limbs in our experience and others;27 however, excellent fracture, modification or alteration of the repair (cast client compliance is a necessary prerequisite to ensure or splint changes, staged destabilization), and ideally, success. identify potential complications before they occur. Ra­ diographs are often used to objectively assess fracture Repair Techniques for Specific Fractures healing. Radiographic union (defined as bone union with resolution of the fracture line) lags behind clini­ Metacarpal and metatarsal cal union (defined as sufficient bridging callus to allow Ideally the fracture configuration of metacar­ weight bearing without additional support to the limb) pal/metatarsal fractures determines the best repair by a minimum of two weeks. Follow-up visits permit option(s); however financial limitations and the surgeon's informed decision-making regarding the timing of cast, preference may also be determining factors. External splint, external skeletal fixation (ESF), and/or implant fixation techniques include cast, 12 transfixation cast,8 removal sequentially over time to gradually increase ESF,24 and circular ESF (CESF).21 Internal fixation the weight bearing of the affected limb, and clinical technique is currently limited to dynamic compression

SEPTEMBER 2009 109 10 plating (DCP); •28 however, newer implants including fractures should have a fair prognosis in the author's limited contact dynamic compression plating (LC-DCP), experience if rigid stabilization using either an ESF or (Q) and locking compression plate (LCP) may become read­ CESF is provided, and antibiotic-impregnated PMMA n ily available in the future. A cast, with the leg placed beads and autogenous bone grafts are used to manage 0 "'O in flex.ion, was used to repair a proximal comminuted osteomyelitis; however, these cases also tend to require '-< 12 ...... '"i metacarpal fracture in an adult male llama. Limited multiple surgeries and a financially committed owner. (JQ extension of the distal limb was possible when the cast g was removed at eight weeks; however, full mobility re­ Humerus > 12 8 turned later. Transfixation casts were used to repa~r With the humerus, fracture configuration deter­ (D 8 ...... '"i metacarpal fractures in three llamas, including one mines the best repair options. Fractures of the humerus (") 18-month-old female with bilateral metacarpal frac­ have been managed conservatively with stall confine­ § tures. 8 Depending on the fracture configuration, it ment27 or with internal fixation.7·17·20·27 Internal fixation >00 00 may be beneficial to place a pin through unaffected bone avoids complications associated with stall rest, includ­ 0 either proximal or distal to the fracture,8 thus facilitat­ ing limb contracture, delayed union, and malunion. 27 (")...... ing repair without open reduction. 9 A single DCP has Intramedullary pins and cerclage are ideally suited for a...... 10 22 24 26 28 17 20 0 been used in six alpacas, • · · · including a six-year­ long oblique fractures. · In selected cases (i.e. crias), ~ 24 0 old pregnant female; however, a fissure detected on the IM pin has been substituted for cortex screws; how­ 1-i; postoperative radiographs became a complete fracture ever, a Valpeau sling was used for additional support.17 to 0 when re-evaluated 14 days later.24 Osteomyelitis was Depending on the fracture configuration, another repair < also believed to be a contributing factor to the initial im­ option for humeral fractures would be an IM interlocking 5· 20 (D plant failure. The plate and screws were removed, and nail. The caudal cortex must be intact when consider­ ~ ~ a Type lB ESF was placed on the palmar aspect of the ing internal fixation using a plate(s). The integrity of (") ..-+-...... limb in order to permit full carpal flex.ion for kneeling. the radial nerve should be assessed prior to surgery, ..-+-...... The ESF was destabilized in stages, beginning at seven since it is prone to damage associated with diaphyseal 0 ~ (D weeks and ending 10 weeks after surgery. This alpaca fractures. Furthermore, special attention must be given '"i was clinically sound four weeks after removal of the to the radial nerve during open reduction as it is located 00 0 ESF. 24 Two DCP were used to repair an open metatarsal between the brachialis muscle and the mid-diaphyseal "'O (D fracture in a three-year-old female alpaca.22 region of the humerus, and can be easily damaged. In ~ Complications were not observed in nine cas­ select cases oflong, spiral fractures of the humerus, the f:; (") es. 8,10,12,22,26,28 Complications associated with fractures authors have used lag-screw fixation for stabilization of (D 00 of the metacarpal/metatarsal bones included fracture the fracture. 00 21 24 22 24 0...... displacement, implant failure, osteomyelitis, · pin Specific complications associated with using a 00 ..-+­ loosening, 8 delayed union, 8 non-union, 22 mild lameness, 22 single DCP without additional support have included '"i carpal hyperextension,22 and metatarsophalangeal carpal contractual deformity due to implant failure ~ ~...... hyperextension in the contralateral limb. 22 A closed, (plate bending and partial pull out of cortical screws) five 0 comminuted diaphyseal metatarsal fracture in a three­ days after fracture repair, 7 and a new fracture occurring p year-old male alpaca was initially repaired using a cast.21 distal to the DCP that resulted in limb amputation. 27 In Radiographic evidence of inadequate stabilization was the one case, a substantial delay prior to surgical repair present five days after surgery. The cast was removed may have contributed to postoperative complications, seven days after surgery and a circular external fixator including worsening of a carpal contractual deformity was applied; healing progressed uneventfully.21 Pin (no evidence of radial nerve paralysis was observed), loosening in transfixation cast and ESF constructs is non-use of the affected limb, and implant failure five caused by infection of the pin tract, thermal necrosis to days after surgery.22 The bent plate was left in place at the adjacent bone during pin insertion, or pin motion. the owner's request, and the fracture healed. Though The carpal hyperextension resolved by bandaging the long-term passive flex.ion and extension of the carpus affected limb for four weeks.22 Infection and non-union did resolve the carpal contractual deformity, a chronic were complications associated with an open metatarsal lameness persisted. 22 No complications were observed fracture in a 10-year-old intact male llama which was when a full-limb fiberglass cast supplemented the inter­ euthanized 41 days after surgery.22 nal fixation using a single DCP plate for a comminuted The surgical treatment for closed metacarpal/ mid-diaphyseal fracture in a five-year-old male castrated metatarsal fractures should have a good prognosis alpaca.17 In two adult llamas, two DCP were used to provided the neurovascular supply to the distal limb repair fractures of the humerus.20 is not compromised. Complications are more likely en­ Complications were not observed in seven cases.17•20 countered with open metacarpal/metatarsal fractures. 22 Complications associated with humeral fracture repair The surgical treatment for open metacarpal/metatarsal are common, including permanent radial nerve damage,

110 THE AABP PROCEEDINGS-VOL. 42 temporary radial neuropraxia, osteomyelitis, implant availability of an appropriately sized IM interlocking failure, and limb amputation;1,I7,20,22·27 one llama was nail (the availability of appropriate stable bone stock at euthanatized four weeks post-surgery due to chronic either end of the femur) and newer plate designs may osteomyelitis. 20 The surgical treatment for humeral potentially improve the surgical treatment and suc­ fractures in camelids should have a good prognosis. I7 cess of femur fractures in both immature and mature camelids. Radius I Ulna Complications were observed in all but three 11 Both internal and external fixation techniques cases •23 and included pin migration, implant/bone fail­ have been used to repair fractures of the radius/ulna,. ure, osteomyelitis, peroneal nerve damage, and chronic Ideally the fracture configuration determines the best lameness.7·22·23 A one-month-old cria died during recov­ repair option(s); however, surgeon's preference may also ery due to pulmonary edema of undetermined etiology. 23 be a determining factor. Though IM pins are not an Malunion of a femoral neck fracture was treated by option for repairing radial and ulnar fractures, the loca­ performing a femoral head arthroplasty; however, this tion of these bones allows for external skeletal fixators. treatment option was not well tolerated and resulted in Transfixation casts have been used successfully to repair a non-functional limb that later required amputation.27 8 22 fractures of the radius and ulna. • Open reduction of Another limb was amputated due to complications that the articular surface of the proximal radius using lag arose after an attempted femoral fracture repair; compli­ screws combined with a transfixation cast has also been cations (immobility and a ruptured bladder) developed used; however, the development of degenerative osteoar­ post-operatively resulting in euthanasia.22 Amputation thritis in the humeral/radial joint can result in chronic of the hind limb appears to be well tolerated by cam­ severe lameness. 22 Closed fractures of the radius and elids27 and should be considered as an alternative to ulna have been typically repaired using either a single euthanasia, in the author's experiences. Catastrophic DCP with additional external support (ie: Robert Jones failure of the femur distal to the DCP occurred 17 days 9 bandage or splint)7,I •26 or two DCP.25 A small wound after surgery in a four-year-old male alpaca, and this along the dorsal aspect of the mid antebrachium did alpaca was euthanized due to the poor prognosis.23 An not adversely affect the repair using a single DCP in a incisional infection without radiographic evidence of 0 young cria. 26 bone/implant involvement 14 days after surgery was "O (D Fractures involving the proximal radius may re­ flushed with chlorhexidine solution; however, multiple :::::s sult in radial nerve damage, and this was observed in draining tracts originating from the implants were ob­ ~ ('.") at least two cases.22·26 Temporary radial neuropraxia served six months later.7 This infection resolved without (D 00 was observed after removal of the transfixation pins in complications after implant removal and antimicrobial 00 4 7 0.. another case. I No complications were observed in four therapy. The majority of case reports on femur fracture r:n ,-+­ 8 9 -..,; · cases. ,I ,22·25 The surgical treatment for radius and ul­ repairs are in younger (< 1 yr) camelids where the softer nar fractures in camelids should have a good prognosis bone density and thinner cortices compared to older s.~ provided the radial nerve and articular joints are not camelids tend to make fracture repair difficult. A four­ 0-· involved. day-old male alpaca cria underwent a second surgery to ? replace the initial repair due to IM pin backout with a Femur DCP. The degree of comminution, eburnation, and loss Though most femur fractures likely arise from of bone stock led to a second implant failure in the distal trauma, a pathological fracture developed at the se­ bone fragment, and the cria was euthanized two days questrum site seven days after sequestrectomy,7 and postoperatively.22 The presence ofmultifocal polyostotic adjacent to multifocal polyostotic aneurysmal bone cysts aneurysmal bone cysts caused implant failure and a new, in a three-year-old llama. I Both modified dynamic IM comminuted femur fracture of the proximal metaphysis cross pins and crossed Steinman pins have been used to and neck in a 3.3-year-old male llama; this llama was repair physeal fractures of the distal femur in several euthanized due to the grave prognosis. I crias.23·27 Simple, long oblique, diaphyseal fractures The surgical treatment of distal physeal fracture may be repaired using IM pin and cerclage wires. In of the femur in immature camelids should have a good contrast, short oblique or transverse fractures are likely prognosis. The surgical treatment of metaphyseal and better candidates for DCP or IM interlocking nails. Most diaphyseal fractures of the femur should have a guarded femur fractures have been repaired with mixed results prognosis. 9 9 using either intramedullary pinsI, ,23 or DCP.7· An IM interlocking nail was used (with some difficulty due to Tibia size limitations of the IM interlocking nail equipment) Tibial fractures can be treated solely by stall con­ to repair a comminuted diaphyseal fracture in a three­ finement, 7 or repaired using either transfixation pins year-old female alpaca without complications.11 The and cast application,9 IM pins,9 DCP,7·9 or IM interlock-

SEPTEMBER 2009 111 ing nails9 depending on the fracture configuration. costs and complications associated with anesthesia, sur­ Stall confinement was used successfully to manage a gery, and implants. Often a second surgery is required to complete, non-displaced dorsal cortical fracture. 7 Full remove the implants after healing. The advantages of limb casts applied to the hind leg do not allow full range external fixation include more flexibility in repair, wound of motion, and may predispose rupturing the peroneus management for open fractures, and usually less anes­ tertius tendon. Simple, long oblique, diaphyseal frac­ thesia, surgery, and implant costs. The disadvantages of tures of the tibia may be repaired using an IM pin and external fixation include malalignment, delayed union, cerclage wire. In contrast, shorter oblique or transverse and non-union. Camelid fractures repaired using either diaphyseal fractures of the tibia may be repaired using internal or external fixation were observed to have simi­ either an ESF, transfixation cast, or DCP, dependiO:g lar morbidity rates. 22 By being familiar with the various on the fracture configuration and surgeon's preference. repair techniques, including their associated strengths Comminuted diaphyseal fractures of the tibia may be and weaknesses, the veterinarian can recommend the repaired using an ESF, transfixation cast, DCP, or IM ideal repair technique on a case-by-case basis. interlocking nail in selected cases based on the fracture Alpacas and llamas tolerate casts quite well. configuration and the surgeon's preference. Fiberglass is the preferred casting material since it is Complications were not observed in four cases. 7·22 easier to work with, stronger, and much more resistant Complications associated with repairs of the tibia in­ to environmental conditions after application compared clude cast sores, slow fracture healing, peroneus tertius to plaster of Paris. The limb must be padded using either rupture, osteomyelitis, sequestra, peroneal nerve dam­ the traditional stockinet or the newer foam resin. The age, hyperextension of the metatarsophalangeal joint, potential pressure points of the limb (accessory carpal and fracture displacement. 22 There were no known bone, calcaneus, talus, and the proximal sesamoid bones) instances of implant failure.7·9·22 Only one case resulted should be carefully padded. Foam resin offers superior in euthanasia due to complications.7 The surgical treat­ padding as it conforms to the limb without excessive ment of diaphyseal fractures of the tibia should have a bulking. Excessive padding is contraindicated since it good prognosis. can become compressed with time, which would leave room for the limb to move within the cast; therefore, 0 Treatment Methods for Fractures increasing the risk of fracture displacement and pos­ "O (D sibly the development of an open fracture. Care must :::::s Fracture repair be taken not to leave finger impressions in either the ~ ('.") The location of the fracture, the degree of soft tis­ resin foam or the fiberglass during cast application, since (D 00 sue and neurovascular damage, open or closed fracture these may cause cast sores. Casts typically require six 00 0.. environment, patient temperament, budget, and the ex­ to eight layers of fiberglass to be sufficiently thick to r:n ,-+­ perience of the surgeon are important factors to consider provide adequate immobilization. The foot is always -·..,; when selecting the type of fracture repair. 3 Furthermore, included in the cast, with the toes extended. Polymeth­ s.~ the AO/ASIF techniques utilized in both small and large ylmethacrylate (PMMA) is used to coat the cast surface 0 animals are well adapted to camelids. 27 The surgical ap­ in contact with the floor to protect the fiberglass from ?-· proaches for each bone have been previously described abrasion. in the literature.1,1,s,10,11,11,19,21,23,24,26-2s A cast may be either a full-limb or a half-limb, Due to their comparative size, orthopedic implants depending on the fracture location and configuration. suitable for small animal patients are more appropri­ Full-limb casts may be used to immobilize fractures up to ate than those used in large animals.27 The methods the proximal metacarpal or metatarsal bones. Half-limb of repair can be divided into either external or internal casts may be used to immobilize fractures of the distal fixation techniques. External fixation techniques include metacarpal or metatarsal bones, including non-displaced the use of casts, splints (Schroeder-Thomas, and spica), physeal fractures (Salter-Harris type I or II), transverse transfixation cast, and an external skeletal fixator diaphyseal fractures, and the phalanges. 9 Ideally, the (ESF). Internal fixation techniques include the use of cast must incorporate one joint above and one below the cerclage wire, screws, intramedullary pins, plates, and fracture. Severely comminuted fractures and fractures the intramedullary interlocking nail. External support involving a joint surface or the metaphyseal region re­ using a cast, splint, Robert Jones bandage, or Velpeau quire greater stabilization than that provided by a cast sling is frequently used to protect internal fixation alone. 9 Casts are considered inappropriate when applied techniques. to proximal limb fractures because this can lead to the The advantages of internal fixation include supe­ creation of the "fulcrum effect" at the fracture site. This rior fracture alignment and anatomical reconstruction, motion can increase soft tissue damage, thereby impair­ which should result in optimal long-term outcomes. The ing angiogenesis and callus formation at the fracture disadvantages of internal fixation include increased site, resulting in malunion.

112 THE AABP PROCEEDINGS-VOL. 42 Most often casts may be maintained in juveniles placement of the proximal pins. Intraoperative radio­ for four to six weeks without being changed. Rapidly graphs can ensure that joints or growth plates are not growing crias may require more frequent cast changes. accidentally damaged during pin placement. The cast must be checked every day for odor, warmth, The pin size selected should not exceed 20% of the position, and use of the affected limb by the patient. diameter of the bone. Larger pins cause marked loss A cardinal sign of developing cast sores is when the of the bone's resistance to torsional loading. The most patient suddenly stops using the affected limb. Veteri­ proximal pin takes the majority of the weight compared nary attention is promptly required, and would likely to the second pin. Therefore, using a larger diameter entail removal of the old cast, examining the limb and, pin in the most proximal hole can increase the strength depending on the fracture healing stage, either a new of this construct. The most distal pin should be at least cast, splint, or a Robert Jones bandage applied. six pin diameters away from the fracture line (e.g. a 4 mm pin should be placed at least 24 mm from the frac­ Schroeder-Thomas splints ture site). The pins should be placed at least four pin A Schroeder-Thomas splint is an appropriate diameters away from each other to minimize the risk technique for fractures distal to the mid-radius and of concentrating the mechanical forces between the two mid-tibia to prevent the fulcrum effect. Insufficient pins, called a "stress riser" effect. Pin divergence yields length and padding are likely the most common faults greater bone fracture resistance compared to parallel pin when devising this construct. The length of the splint configuration. 13 Aligning the pins parallel to each other is measured while the patient is standing on its unaf­ in a lateral to medial plane, but diverging at a 30 degree fected contralateral limb. If the distal phalanges touch angle, dorsal to caudal, can also increase the torsional the bottom of the splint then the length is too short and stability of the construct5 but not the axial stability of will not provide adequate stabilization. The loop of the the configuration. 14 We typically use centrally threaded, splint must be firmly placed in either the axilla or in­ positive profile, self-tapping pins. Ideally, the holes are guinal area to facilitate maximal weight transference. pre-drilled 0.05-0.10 mm smaller than the pin diameter Therefore, the loop must initially be made oversize to to allow radial loading. Positive profile pins provide provide sufficient space for ample padding to reduce the superior bone-implant interface. Pre-drilling is required development of decubital ulcers. The patient is placed to prevent significant thermal and mechanical injury to in lateral recumbency using a combination of sedation the bone prior to pin insertion (the exception to this rule and restraint. The fracture is reduced, and the limb is might be when dealing with a neonatal patient). Ther­ immobilized to the Schroeder-Thomas splint using tape. mal necrosis is reduced or eliminated by using sharp drill The limb must be firmly attached to the splint frame bits, low drill speeds (<250 rpm), continuous irrigation of to prevent rotation of the limb along the splint during the drill bit, and periodically cleaning out the accumu­ ambulation. Patients should be assisted to stand for lated debris between the flutes. The excess pin material the first couple days after splint application until they is cut off, leaving sufficient length to be incorporated learn to rise under their own power. Initially, patients in the cast. Stockinette or foam resin padding is then are usually unable to rise after lying down on top of the applied. The pin ends are gently pushed through the splint. Complications include poor alignment, malunion, first three layers of fiberglass as it is applied. The final delayed healing, and decubital ulcers. three layers are applied over the pin ends. To prevent pin strike-through by abrasion, PMMAis applied on the Transfixation pinning and casting fiberglass covering the pin ends and the bottom of the A transfixation cast refers to the placement of cast overlying the foot. This construct is significantly transcortical pins through the bone proximal to the in­ stronger than ESF since the distance between the bone jury, followed by application of a cast. The cast begins and fiberglass is decreased compared to that between proximal to the transcortical pins, and extends distally, the bone and clamps in a Type II ESF. The primary incorporating both the pins and the entire limb including disadvantages of this construct include poor access to the foot. Therefore, the full body weight is transferred wounds under the cast, greater difficulty in cast removal, to the cast by the transcortical pins and transmitted and the potential for cast sores to develop. 3 through the cast to the ground. The advantages include minimal disruption of the fracture site, thus maximiz­ External skeletal fixators ing fracture biological osteosynthesis; relatively quick External skeletal fixator requires two transfix­ and inexpensive to apply, requiring little specialized ation pins placed both above and below the fracture equipment; and can be used to stabilize comminuted line. These pins can then be connected using connect­ metacarpal and metatarsal fractures. Compared to a ing bars, or a fiberglass cast. This construct typically standard cast or splint, this technique requires a general provides greater fracture stability than a transfixation anesthetic and increased surgical skill to ensure correct cast and can be used to manage open wounds. Diaphy-

SEPTEMBER 2009 113 seal fractures of the radius/ulna, metacarpus, tibia, Bone plating of fractures and metatarsus can be repaired using this technique, The techniques used to apply dynamic compression provided there is sufficient bone to place all four pins. plating (DCP) to a fracture in a camelid are similar to An advantage of this technique is that normal range those for other species. 4 Since the bone is relatively soft of motion for all joints is maintained; however, trans­ in juvenile camelids, care must be taken not to over­ articular pins can be placed either above or below the tighten the screws and strip the cortical bone. Plate lut­ 2 fracture line to improve stability in certain instances. •9 ting, using antibiotic-impregnated PMMA, can be used Since the pins are equally loaded in this construct, they to increase the bone implant contact.4 The disadvan­ can be of the same diameter. Pin size and placem~nt tages of the DCP technique include the requirement for techniques have been previously mentioned. Unless increased surgical skill, specialized equipment, surgical fiberglass is used as a connecting bar, the pins must time, and cost. The implants can loosen or break, thus be aligned to facilitate clamping to the connecting bar. requiring removal at a later date. Once the fracture is The connecting bar should be placed with the clamps clinically healed, the implants do not require removal towards the limb, approximately 1 cm away from the unless they are causing lameness. skin to allow for postoperative swelling. This distance should be kept to a minimum, since doubling the bone I ntramedullary interlocking nails to connecting bar distance reduces the resistance to The successful use of an intramedullary inter­ compressive loads by approximately 25%. If fiberglass locking nail has been reported in the literature. 11 This is used as a connecting rod, the limb distal to the cast technique likely requires the greatest degree of surgical should be bandaged for the first few post-operative days skill, specialized equipment, and cost. This construct to prevent swelling. Unlike other repair techniques, the is best applied in buttress support of femoral, tibial27 20 21 ESF has an additional advantage in that the implants and humeral fractures. , The central location of this may be sequentially removed over time to gradually implant provides greater strength compared to other 15 16 increase the axial weight bearing of the affected limb. internal and external repair techniques. • This or­ These implants are completely removed under sedation thopedic implant typically does not require removal once the fracture is clinically healed. The ring fixator after the fracture is clinically healed unless it is causing 0 is a modification of the standard ESF system. Though lameness or other problems. "d ('[) more costly, the superior flexibility and versatility of ~ ~ the ring fixator offers potential solutions for specific References (') (') ('[) situations that may not be repairable using other fixa­ en tion methods. 1. Anderson DE, Midla LT, Scrivani PV, et al: Multifocal polystotic en aneurysmal bone cysts in a llama. J Am Vet Med Assoc 210:808-810, 8-:r:n 1997. q- Intramedullary pins and cerclage wire 2. Anderson DE, St Jean G, Desrochers A: Repair of open, comminuted Not all bones and fracture configurations can be fractures of the radius and ulna in a calf with a transarticular Type [ repaired using intramedullary (IM) pins and cerclage II external skeletal fixator. Agri-Pract 15:24-28, 1994. o· 3. Anderson DE, St Jean G: External skeletal fixation in ruminants. p wire. Access to the longitudinal axis of the bone is re­ vet Clin North Am Food Anim Pract 12:117-152, 1996. quired without damaging an adjoining joint; therefore, 4. Auer JA: Principles of fracture treatment, in Auer JA, Stick JA (eds): this technique is limited primarily to humeral and Equine Surgery, ed 3. St. Louis, Saunders, 2006, pp 1001-1030. femoral bones, specifically when they have long, oblique 5. Egan J, Shearer J: Behaviour of an external fixation frame incor­ fractures. This technique requires a minimum fracture porating an angular separation of the fixator pins. A finite element approach. Clin Orthopedics 223:265-274, 1987. line length that is twice the bone diameter when using 6. Fowler M: Medicine and Surgery of South American Camelids: cerclage. The IM pin should fill the medullary canal at Llama, Alpaca, Vincua, Guanaco, ed 2. Ames, Iowa State University the isthmus of the bone. Intraoperative radiographs can Press, 1998. 7. Johnson CR, Baird AN, Baird DK, Wenzel JG: Long-bone fractures facilitate correct pin placement in the distal metaphysis in llamas: six cases (1993-1998). J Am Vet Med Assoc 216:1291-1293, to avoid inadvertent penetration of the adjoining joint. 2000. The complications of this particular technique include 8. Kaneps AJ, Schmotzer WB, Huber MJ, Riebold TW, Watrous BJ, damage to the distal joint during pin placement, pin Arnold JS: Fracture repair with transfixation pins and fiberglass cast migration postoperatively, and osteomyelitis second­ in llamas and small ruminants. J Am Vet Med Assoc 195:1257-1261, 1989. ary to a pin tract infection. This configuration is not 9. Kaneps AJ: Orthopedic conditions of small ruminants. Llama, desirable for short oblique, transverse, comminuted, or sheep, goat, and deer. vet Clin North Am Food Anim Pract 12:211- segmental fractures. Once the fracture is healed, the pin 231, 1996. and cerclage wires do not require removal unless they 10. Krauss R: Fallbericht: metakarpusfraktur bei einem alpakahengst. Kleintierpraxis 36:529-602, 1991. are causing lameness or other problems.

114 THE AABP PROCEEDINGS-VOL. 42 11. Lillich J, Roush J, DeBowes R, Mills M: Interlocking intramedul­ 20. Rakestraw PC: Fractures of the humerus. Vet Clin North Am Food lary nail fixation for a comminuted diaphyseal femoral fracture in an Anim Pract 12:153-168, 1996. alpaca. Vet Comp Ortho and Trauma 12:81-84, 1999. 21. Rubio-Martinez LM, Koenig JB, Halling KB, Wilkings K, Schulz (Q) 12. Manning JP: Fracture of the metacarpal bones in a llama. J Am K: Use of a circular external skeletal fixator for stabilization of a com­ n Vet Med Assoc 129:136-137, 1956. minuted diaphyseal metatarsal fracture in an alpaca. J Am Vet Med 0 "'O 13. McClure S, Watkins J,Ashman R: In vitro comparison of the effect Assoc 230:1044-1047, 2007. '-< of parallel and divergent transfixation pins on breaking strength of 22. Semevolos SA, Huber MJ, Parker JE, Reed SK: Complications ...... '"i equine third metacarpal bones. Am J Vet Res 55:1327-1330, 1994. after orthopedic surgery in alpacas and llamas: 24 cases (2000-2006). (JQg 14. McClure S, Watkins J, Bronson D, et al: In vitro comparison of the Vet Surg 37:22-26, 2008. standard short limb cast and three configurations of short limb trans­ 23. Shoemaker RW, Wilson DG: Surgical repair of femoral fractures > 8 fixation casts in equine forelimbs. Am J Vet Res 55:1331-1334, 1994. in New World camelids: five cases (1996-2003). Aust Vet J 84:148-152, (D 15. McClure SR, Watkins JP,Ashman RB: In vivo evaluation ofintra­ 2007...... '"i medullary interlocking nail fixation of transverse femoral osteotomies 24. Staudte K, Gibson N: Type lB external fixation of a metacarpal (") in foals. Vet Surg 27:29-36, 1998. fracture in an alpaca. Aust Vet J 81:265-267, 2003. § 16. McDuffee LA, Stover SM, Taylor KT, Les CM: An in vitro biome­ 25. St Jean G, Bramlage LR, Constable PD: Repair of fracture of the >00 chanical investigation of an interlocking nail for fixation of diaphyseal proximal portion of the radius and ulna in a llama. J Am Vet Med 00 0 tibial fractures in adult horses. Vet Surg 23:219-230, 1994. Assoc 194:1309-1311, 1989. (")...... 17. Newman KD, Anderson DE: Humerus fractures in llamas and 26. Tee S, Dowling B, Dart A: Treatment oflong bone fractures in South a...... alpacas: seven cases (1998-2004). Vet Surg 36:68-73, 2007. American camelids: 5 cases. Aust Vet J83:418-420, 2005. 0 18. Poulsen KP, Smith GW, Davis JL, Papich MG: Pharmacokinetics 27. Turner AS: Surgical conditions in the llama. Vet Clin North Am ~ of oral omeprazole in llamas. J Vet Pharm Therapeut 28:539-545, 0 Food Anim Pract 5:81-99, 1989. 1-i; 2005. 28. Zanolari P, ZulaufM, Nitzl D, Ueltschi G, Steiner A: [Open diago­ to 19. Purdy C, Lochner F: Proximal radial fracture in a llama. Equine nal fracture of metatarsus Ill/IV and internal fixation in an alpaca]. 0 < Pract 7:12-15, 1985. Schweiz Arch Tierheilkd 145:378-385, 2003. 5· (D ~ ~ (") ,-+-...... ,-+-...... 0 ~ (D '"i 00 0 "'O (D ~ f:; (") (D 00 00 0...... 00 ,-+- '"i ~ ~...... 0p

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