CHAPTER I I The Application Of The lhzarov Frame In Foot And Ankle Surgery

George R. Wto, D.PM.

The llizarov method of external fixation applies the wires to stabllize bone. The wires, when placed scientific principles of tissue neogenesis in dealing under tension and connected to a circular frame, with a wide variety of orthopaedic problems. provide a high degree of osseous stability. The use These include a variety of osseous deformities, of smaller wires reduces soft tissue and bony reac- such as bone infections, limb length discrepancies, tion, when compared to the larger pins. Vhether fracture healing, non-unions, and congenital the frame is used for distraction or for stability pseudarthroses and malformations. Skin and soft of a joint or bone, full weight-bearing can be tissue defects and the vascular insufficient limb are allowed postoperatively. During the entire treat- also responsive to this form of therapy. The ment period, both the weight-bearing function of Ilizarov principle, in shofi, respects osteogenic tis- the limb and the range of motion in the adjacent sue and its vascular supply, while preserving the joints are preserued. This is actually one of the weight-bearing function of the limb. requirements for success with this method. Conventional surgical treatment of foot and Elements of the llizarov compression- ankle deformities is often limited by the severity of distraction apparatus can be divided into primary and the deformity, or inhibitive due to the risk of fail- secondary components. The prknary components are ure. In these instances, alternatives to traditional standard parts that join the skeleton to the finished modes of treatment can be particularly helpful. frame, such as transosseous wires, rings, and wire tix- These situations include severe deformities in ation bolts. The secondary components are the special which the mobility of the overlying skin is insuffi- elements used to constftict the frame of the apparatus, cient to permit osseous correction. Various such as threaded and telescopic rods, connecting techniques are currently being used to deal with plates, hinges and posts, and nuts and bolts. Various this problem, including staged manipulations after wrenches are also considered secondary components release of the foot, along with staged fusion or of the apparatus. To use the llizarov apparatus, one additional releasing procedures. Traditional meth- should also have avallable the equipment needed for ods of correcting foot deformities in the older child standard osteosynthesis techniques, including and adult often require extensive bone resection, osteotomes, power drills, mallets, and pliers. resulting in significant shortening of the foot. Vith The dynamometric wire tensioner is a very severe multi-directional deformities, correction impofiant instrurment which allows one to tension the through resection of large section of bone is often wires to an exact force, improving stability of the an inappropriate form of treatment. entire bone-frame construct. The wires should be ten- The mechanical characteristics of the Ilizarov exrter- sioned from 50 to 130 kilograms. The exact amount nal fixator can be compared to that of the standard of tensioning depends upon the weight of the uni-planar extemal fixator. The most colrlnon type of patient, local bone quality, treatment plan, and the uni-planar extemal fi>rators is tl-re Hoffnrann device. The 1oca1 frame construct. The wires can be retensioned Hoffmann extemal fixator utilizes large diameter threaded or further tensioned during the treatment of the plns (M mm) to stabilize osseous segments. The major patient. In most instances, the entire apparatus is ad:rantages of this type of fixation is that the uni-planar made of stainless steel, which allows for maximum system miflmizes the transfixion of soft tissues, and js a strength and stability. However, graphite rings are less bulky device. In most instances, the use of this type now available which provide greater strength to the of e{emal fixation does not allow for full weight-bearing. frame with less weight. In addition, the graphite rings The llizarov frame in contrast, utilizes non- are radiolucent allowrng for ease of radiographic threaded, small diameter (1.5 - 1.8 mm) Kirschner interpretation. CHAPTER 11 47

The unique design of the llizarov fixator and subtalar joints. If the limb is shortened with compares favorably with other external fixators. fusion, distraction osteogenesis is possible follow- The ideal fixator should demonstrate high shear ing 20 to 30 days of compression. This allows for stiffness and low axial stiffness. It is accepted that limb lengthening within the arthrodesis site. shear forces at the fracture site are deleterious One of the main indications for the use of the to osteogenesis, whereas cyclic axial micromotion Ilizarov technique is fusion of the ankle joint. Joint promotes bone repair and regeneration. The resection can be carried out in the conventional Ilizarov apparatus, constructed of parallel rings fashion, and a four ring apparatus is applied connected with threaded rods, assumes an axiaT involving the tibia, talus, calcaneus and forefoot. configuration. It has high shear stiffness, particu- The fusion is stabilized and placed in compression larly when the "olive" wires are used. The "olive" with four threaded rods connecting the distal ring wire, or wire with a stopper, is used so that force and the calcaneal ring. Subtalar foint fusion can is directly applied to the bone fragment through also be achieved with a very similar construct. The tension on the wire. Common applications of the main advantage of fusion with the Ilizarov tech- olive wire include correction of angular deformity, nique is that fu1l weight-bearing can be achieved prevention of undesirable displacement, transpofi immediately. One also has the option to intermit- of an oss€ous fragment (longitudinally or trans- tently tighten the frame in the postoperative period versely), increase stability and rigidity of the resulting in greater compression of the fusion site. system, and to aid in the reduction of a fracture. The Ilizarov method permits stable fixation The apparatus consists of a system of rings of limb segments adjacent to an abnormal joint. and semi-rings, connected with threaded rods By distraction, translation and angulation, sub- (1 mm pitch) or special telescoping rods. The orig- luxed or dislocated joints can be realigned. inal Ilizarov apparatus consisted of 32 basic Through correct hinge placement in the axis of mechanical parts. The varied combinations of these joint rotation, controlled joint motion can be used parts allows construction of a customized appara- to avoid subluxation. Gradual distraction of peri- tus, individualized to the specific needs of each articular soft tissues can be achieved at a rate of 7 patient. The versatility of the system allows for mm per day, which can permit one to three more than 700 different types of application. degrees of correction per day. Frames can be built to produce lengthening, short- Arthrodiastasis, or distraction of a joint, must ening, angulation, rotation, and translation in any transfer forces from the bone to the soft tissues. direction. Correction can be achieved immediately, Ligaments, tendons and capsular stftictures are pri- or graduaily by applying force over an extended marily composed of collagen, which should period or time. respond to controlled distraction in a predictable The llizarov frame can be used for graduai manner based upon the biology of distraction correction of foot deformities without the limita- osteogenesis. Contracture of muscle involves tions of prolonged treatment, cast sores, myofibril structures with active and passive elastic- incomplete correction, or damage to growth plates ity. Distraction of muscle is often painful and less or joints. Application of compression or distraction predictable. Nerves are known to regenerate at a forces can be used to correct a deformity in any rate of one millimeter per day following axonot- given part of the foot, ankle, or leg. mesis. Nerve distraction, gradual or slow, may still The Ilizarov method offers many advantages result in paresthesias, which are usually transient. over casting techniques in that gradual adaptation Skin is highly eiastic and can easily adapt to any occurs through a constantly applied force. Three lengthening process, with the exception of skin dimensional control is possible (axial, angulation grafts, free flaps, and rotational flaps. \7ith these and translation). In addition, the skin is always exceptions, slower distraction may be necessary. visualized directly, and correction is usually faster Blood vessels retain proliferative activity and can than with casting. usually respond to gradual distraction by growth. The llizarov technique provides an ideal and However, the cornerstone of the Ilizarov method is minimally invasive method for fusion of the ankle the biologic law of "tension stress" in bone and soft CHAPTER 11 49 pofiional to time. The transosseous wires minimize Grill G, Franke J: The Ilizarov Distractor for the Corection of Relapsed or Neglected Chtbfoot Bone Surg 59(B),593-597, 1987. this problem small diameter J Joint by their and stability Harvey JP: Editorial Comment (on the Ilizarov Technique) Contemp under tension. Vhen the wires must cut through Ortbop 17 (2):11, 1988, scar Ilizarov GA: The Tension-Stress Effect on the Genesis and Gronth of the skin, the trailing is well-formed and clean. Tissues: Paft 1I. The InJluence of the Rate and Frequency of 7. Frequent Out-Patient Monitoring Distraction. Clin Orthop Rel Res 239:263-28r, 1.989. The patient who wears ao apparatus must be fre- Ilizarov GA: Modern techniques in Limb Lengthening: Clinical Application of the Tension-stress Effect for Limb Lengthenrng. Clin quently monitored on an out-patient basis. Each Ortbop Rel Res 2s0:8-26. 1990. visit may be quite time consuming. Paley D: Modern Techniques in Limb Lengthening: Editorial Comment. Clin Ofihop Related Res 250:2-3, L990. Paley D, Fleming B, Catagni M, Kristiansen T, Pope M: Modern Techniques in Limb Lengthening: Mechanical Evaluatlon of BIBLIOGRAPTIY Extemal Fixators Used in Limb Lengtheniog. Clin Ortbop Rel Res 250:50-57,1990. Pearson RL, Perry CR: The Ilizarov Technique in the Treatment of Cattaneo R, Vi1la Catagni Tentori Limb Lengthening in A, M, L: Infected Tibial Nonunions. Ortbop Reu 1.8(5)$09-61.3, 1989. Ilizarov's Method. Int Ot'tbop 12 (.i:173-179, 1.988. Achondroplasia by '$Tagner H: Operative Lengthening of the Femur. Clin Oxbop Cattaneo R, Villa A, Catagni M, Bell D: Modern Techniques L36:L25, 1978. in Limb Lengthening the Humerus Using the llizarov Technique. of Villa A, Paley D, Catagni M, Be1l D, Cattaneo R; Modern Techniques Clin Ofibop Rel Res 250:1,17-124J,990. in Limb Lengthening: Lengthening ofthe Forearm by the Ilizarov Coleman SS, Stevens PM: Tibial Lengthening. Clin Ortbop 136:92, 1978. Technique. Clin Ortbop Rel Res 250; 1,25-1,37, 1,990. Grant AD, Atar D, Lehman rWB: Ilizarov Technique in Correction of Relapsed or Neglected Cltrbfoot J Bone Joint Surg 698;593, 1987.