SUPRAMALLEOLAR OSTEOTOMY: INDICATIONS AND TECHNIQUE
January 1st, 2003
Emmanouil D. Stamatis, M.D. and Mark S. Myerson, M.D.
SYNOPSIS
Several studies discuss the use of supramalleolar osteotomy to correct distal tibial and foot and ankle deformities in the pediatric population, but the use of distal tibial osteotomies to correct pathologic entities of the adult foot and ankle has received limited attention in the literature. This article describes the indications for the distal tibial osteotomy, reviews the current literature, and presents our unpublished experience with acquired foot and ankle deformities in the adult population. In particular, we focus on preoperative planning and surgical technique.
INTRODUCTION
Several studies discuss the use of supramalleolar osteotomy to correct distal tibial and foot and ankle deformities in the pediatric population for indications such as deformities secondary to residual equinovarus after poliomyelitis or correction of clubfoot deformity,14,17,25 growth disturbances after physeal injury,23 and paralytic conditions such as myelomeningocele.1,30 The use of distal tibial osteotomies to correct pathologic entities of the adult foot and ankle has received limited attention in the literature.6,8,18,19,21,26,27 This article describes the indications for the distal tibial osteotomy, reviews the current literature, and presents our unpublished experience with acquired foot and ankle deformities in the adult population. In particular, we focus on preoperative planning and surgical technique.
INDICATIONS
Osteotomy of the distal tibia is a corrective procedure to realign the limb in the setting of deformity, but this procedure has also gained increasing popularity as a treatment alternative for the management of arthritis of the foot and ankle.2,8,21,26,27 Heywood8 reported on the outcome of eight patients (nine feet) who underwent distal tibial osteotomy for management of aggressive rheumatoid arthritis of the hindfoot with stiff equinovarus deformity and persistent pain. In all cases the deformity had occurred in the subtalar joint complex, and structural changes in this joint were evident in radiographs. The severe pain in such cases was usually in the pressure points under the prominent fifth metatarsal head. Additionally, both ankle and tarsus were involved but were not excessively painful, with pain resulting from weightbearing in varus position. Heywood hypothesized that such symptoms would abate if the foot was rendered plantigrade. He performed an anterolateral closing wedge supramalleolar osteotomy as an alternative to a triple arthrodesis. The decision to perform such an osteotomy rather than a fusion was based on the idea that it was worthwhile to preserve any residual and not unacceptably painful tarsal motion. The resulting ankle joint would be oblique, but Heywood hypothesized that no heavy demands would be placed on such feet due to built-in constraints of the severely crippled rheumatoid patients. At an average 5-year follow-up, 78% of the patients had satisfactory results according to his grading system. Pearce et al.21 reported a small series of seven patients with hemophilia who underwent a supramalleolar osteotomy for correction of a painful and valgus deformed arthritic ankle joint due to recurrent episodes of intraarticular bleeding events. His consideration was that such a valgus deformity usually results from progressive disease in the mature joint. Pearce used a medial closing wedge supramalleolar osteotomy secured with a single staple. The osteotomy improved their functional scores, reduced pain, and decreased the frequency of bleeding at a mean 9-year follow-up.
Takakura et al.27 published their experience with distal tibial osteotomy in 18 patients with primary (idiopathic) osteoarthritis of the ankle joint. This type of arthritis is rare, and the pathophysiology of this disorder is not clear. Preoperative measurements in these cases showed a varus tilt of the ankle joint, anterior opening of the distal joint surface and a hypo plastic medial malleolus. The preoperative tibioplafond angles (TAS) and lateral tibial articular angles (TLS) averaged 82.3° and 77.4°, respectively. In the normal Japanese population, the mean TAS and TLS are 89° and 81°, respectively.27 These researchers noted that the preoperative angles were probably a result of the Japanese practice of sitting cross-legged or with their legs tucked beneath them, because such abnormalities were not detected in children. With the constant varus attitude of the crossed ankle, there is a varus stress on the tibiotalar joint that may lead to an abnormal joint wear pattern. This may be consistent with observations of patients with chronic ankle instability either as a result of ligamentous laxity or associated with the cavovarus foot deformity. However, Takakura et al. do not advise reconstruction of the lateral ligament because even without ligamentous reconstruction, ankle stability was gradually regained after correction of TAS.27
All patients in this series had an intermediate stage of osteoarthritis (stages 2 and 3, according to their classification scheme), without obliteration of the whole joint space. This was always confirmed preoperatively with a diagnostic ankle arthroscopy. The surgical rationale was to realign the mechanical tibial axis to the distal tibial articular surface, shifting the loading stresses away from the medial side of the ankle joint. In the first six cases, these researchers used a closing wedge or oblique osteotomy. Bone union was slow, and the 12 remaining patients underwent an anteromedial opening wedge osteotomy. Ten of the 18 patients underwent a diagnostic ankle arthroscopy from 10 to 28 months after the osteotomy. In seven patients who had substantial correction of the preoperative deformity, there were findings of fibrocartilage tissue growth in areas of the medial articular surface. These areas were denuded of cartilage during the first arthroscopic examination. Takakura et al. note that this growth demonstrates the value of load redistribution. At an average 7-year follow-up, results were excellent in six patients, good in nine, and fair in three, according to Takakura’s scoring system.
To date, there is only one report on the use of supramalleolar osteotomy for the treatment of posttraumatic ankle arthritis.26 In this study Takakura et al., reported the outcome of nine patients who underwent a supramalleolar osteotomy for the treatment of a posttraumatic varus deformity of the ankle. Four patients had an early stage of ankle osteoarthritis (stage 1 according to their classification system) and five patients an intermediate stage (stages 2 and 3 according to their classification scheme). All the patients in this series had posttraumatic angular deformity with TAS and TLS angle reduced to 70°± 7.8° and 75.1° ±5.8°, respectively. The approach was similar to that described in their previous study, utilizing an opening wedge osteotomy. At an average follow-up of over 7 years, results were excellent in four patients, good in two, and fair in three.
In addition to the management of osteoarthritis, the distal tibial osteotomy has also been reported as a useful adjunct to the treatment of distal tibial malunion. Graehl et al.6 reported on eight patients with distal tibial varus malunion who were treated with a low tibial osteotomy. Patients in this series had a malunion with a mean angulation of 15°. Seven of eight patients improved after the osteotomy. These investigators used dome osteotomies for coronal plane deformities and wedge osteotomies for biplane and sagittal plane deformities, but complications were frequent. Three patients had pin tract infections and in two of them drainage ceased only when the external fixation was removed. This increased incidence of infection was probably due to inadequate pin tract care and lack of close observation for early signs of infection. Two patients had inadequate correction of the deformity and one loss of initial correction after a fall, with an unrecognized residual deformity during the repeated reduction. The investigators believed that adequate correction could be obtained by achieving maximum correction during surgery and verifying that with meticulous intraoperative radiographic control.
In our institution, we have advocated the use of distal tibial osteotomy to address a variety of pathologic entities including the following.
1. Correction of distal tibia fracture malunion without osteoarthritic changes of the ankle joint.
2. Correction of distal tibia malunion with concomitant osteoarthritic changes of the ankle joint.
3. Correction of ankle fusion malunion.
4. Secondary ankle joint arthritis with deformity due to intraarticular trauma or avascular necrosis of the distal tibia.
5. Correction of ankle valgus deformity in patients with a ball and socket ankle joint configuration due to tarsal coalition.
6. Osteoarthritis of the ankle joint secondary to ankle instability or a cavovarus foot deformity.
7. Preservation of foot alignment in cases of deformities due to neuroarthropathy.
8. Correction of limb alignment in adolescents and young adults due to growth plate injury.
9. Correction of lower limb alignment as staged planning for a total ankle replacement.
IMPLICATIONS OF DISTAL TIBIA DEFORMITY AND ANKLE ARTHRITIS
There does not appear to be a consensus in the literature regarding the acceptable limits of angular deformity of the tibia and the potential for development of tibiotalar arthritis. These observations are based on the quantitative relationships of the extent of angulation, the level at which this deformity occurs, the corresponding increase in cartilage pressure in the ankle joint, and the long-term effects of these pressures on the joint cartilage.13
It would seem logical that as deformity of the distal tibia increases, the incidence of tibiotalar joint stress will also increase. However, clinical observations and biomechanical studies are not in agreement on this question. Merchant and Dietz15 reported on the radiographic appearance and the clinical function of the knee and the ipsilateral ankle joints. They found that neither were statistically different in patients who had a combination of 5° angulation in the frontal plane and 10° or more in the sagittal plane when compared with patients who had less angulation. Kristensen et al.10 reported on angulation exceeding 10° that was compatible with normal function and absence of pain. On the other hand, biomechanical studies on cadavers have shown a decrease of the contact surface area in the ankle joint up to 40%.28,29 In a cadaver model study, Tarr et al.28 found that proximal and middle third tibial deformities up to 15° did not significantly alter the tibiotalar pressure distribution. They also found that distal tibial deformities significantly alter total tibiotalar contact area, contact shape, and contact location. Greater changes were observed with deformities in the sagittal plane (as much as 42% for anterior bow of 15° and 40% for posterior bow of 15°). Ting et al.29 confirmed these findings and also found that the subtalar joint (acting as a torque transmitter and compensating for coronal plane tibial deformities) plays a significant role in maintaining the talus in normal position relative to the tibia. Thus, the presence of hindfoot stiffness severely affects tibiotalar contact pressure changes from angular deformities of the tibia. In theory, the realignment of the tibial mechanical axis to the distal tibial articular surface decreases the risk of degenerative disease. Cooper et al.(5) noted that a 10° valgus osteotomy at the supramalleolar area decreases the force on the medial talar dome by a mean of 42% (Cooper, P. S., Posteraro, A. F., and Nowak, M. D.: Biomechanical analysis of the low tibiotalar (supramalleolar) osteotomy for ankle arthrosis, presented at the 13th Annual Summer Meeting of the American Orthopaedic Foot and Ankle Society, Monterey (CA), July 17, 1997). However, in the absence of joint wear and compensated biomechanical deformity, it is difficult to extrapolate these results to the clinical situation.
The ability of the foot to tolerate deformity above the ankle depends on the flexibility of the foot and the ability of the foot to compensate for these deformities. With a deformity such as distal tibia varus or valgus, the forefoot must remain plantigrade to bear weight comfortably. If a varus malunion of the distal tibia is present, the subtalar and transverse tarsal joint must evert to maintain a plantigrade forefoot. The opposite is true for a valgus distal tibia deformity. If the hindfoot is stiff to begin with, there will be less capacity for the foot to compensate for supramalleolar deformity. The normal inversion motion of the hindfoot is approximately 20°, and the eversion is about 5°.22 The hindfoot can therefore compensate for a valgus supramalleolar deformity far more than it can compensate for a varus tibial malunion. This information should be helpful in planning correction of a deformity and anticipating the ability of the foot and ankle to tolerate these changes. It is likely that distal tibial angulations of more than 10° will not be well tolerated. We recommend a distal tibial osteotomy in patients with distal tibial angulation over 10° (Fig 1A-D).
The recommendation may change if the hindfoot is painful or stiff, and realignment is imperative in the presence of tibial malunion with concomitant degenerative changes in the ankle joint. In these situations, the goal of surgery is to beneficially alter or decrease the contact pressures on the degenerated cartilage with mechanical realignment. For these patients, the treatment goal is joint preservation to maximize the longevity of the tibiotalar articulation. As noted in the reports described previously, supramalleolar osteotomies have a beneficial effect in treatment of ankle arthritis. One of the prerequisites for a successful total ankle replacement is a balanced mechanical axis of the foot with respect to the lower leg. If either subtalar or supramalleolar deformity is present, the increased stresses on the tibiotalar joint may increase the likelihood of failure. For preservation of limb alignment, supramalleolar osteotomy can serve as a preliminary step before total ankle replacement (Fig. 2A-D). Generally, we wait three to four months following the supramalleolar osteotomy and then proceed with the total ankle replacement.
The same concepts of realignment apply to the ankle arthrodesis malunion. With the ankle joint fused in equinus, a leg length discrepancy is present because the involved leg is lengthened. This leads to a recurvatum thrust on the knee joint, an uneven gait pattern, and increased stress concentration across the midfoot.5 There is an increased likelihood of developing talonavicular arthritis following ankle arthrodesis, which is compounded with any equinus malunion. In a recent long-term follow-up study Coester et al.4 found that ankle fusion is associated with premature deterioration of other joints of the foot. Specifically, they found that degenerative changes of the ipsilateral subtalar, transverse tarsal, naviculocuneiform, tarsometatarsal, and first metatarsophalangeal joints were more severe than the changes in these joints on the contralateral side. The clinical impact of their observations was based on the significant differences between the two sides with respect to overall activity limitation, pain, and disability, with the involved side being more symptomatic. With the ankle fused in dorsiflexion, repetitive calcaneal impact and stress concentration on the heel pad during the heel strike phase leads to chronic heel pain and gait impairment.5 In patients with an insensate foot due to neuropathy, this may also cause a skin breakdown. Varus malunion of the ankle fusion leads the patient to walk on the lateral side of the foot. This inverted position of the subtalar joint increases the rigidity of the transverse tarsal joints with substantial increase in stress concentration and subsequent degenerative changes and pain. There is increased stress under the fifth metatarsal head or base, and patients may develop painful callosities and stress fractures.5 Valgus malunion generates increased stresses along the medial aspect of the knee and hindfoot joints as the foot becomes more flexible, which results in flatfoot posture.5 Rotational malunion leads to a painful knee or hip joint due to abnormal rotation of the limb to compensate for the deformity.5 A revision of the ankle arthrodesis malunion is required for all of these deformities, but not at the level of the ankle itself. Based upon the mechanical axis, a supramalleolar osteotomy is recommended.
We have noted the indications for distal tibia osteotomy in cases of primary or secondary osteoarthritis of the ankle by shifting the loads and redistributing stresses to a part of the ankle joint not involved in the degenerative process (Fig. 3A-B). This procedure is based upon the clinical successes reported by Takakura et al.26,27 The difficulty with reproducing these reported results are likely the result of differences in pathogenesis, patient population, ankle mechanics, and the extent of and direction of deformity. The redirection of forces about the tibiotalar joint can be approached either above or below the ankle. An interesting cadaver study24 reported on the effects of medial and lateral displacement calcaneal osteotomies on tibiotalar joint contact stresses. In that study, a lateral displacement calcaneal osteotomy unloaded the most medial zone of the tibiotalar joint and increased loading of the most lateral zone. Medial calcaneal displacements have the opposite effect. Specifically, they found that for an applied load equal to two times body weight, a 1-cm lateral displacement shifted the center of pressure in the tibiotalar joint an average of 1.06 mm laterally, whereas a 1-cm medial displacement shifted the center of pressure an average of 1.58 mm medially. The authors suggest that translational calcaneal osteotomies could be used in clinical practice to unload focal areas of degenerated cartilage along the medial and lateral parts of the tibiotalar joint.
We have attempted to correct tibiotalar varus deformity by working predominantly below the level of the ankle, but this has not been successful. Despite what appears to be an adequate realignment of the hindfoot with lateral calcaneal osteotomy, ankle ligament reconstruction, and deltoid release, the ankle tends to fall back into varus. This may be due to the erosion of the medial plafond as a result of the chronic varus malposition of the talus or a contracted posterior tibial tendon.
We also advocate the use of distal tibial corrective osteotomy in cases of ankle deformities due to tarsal coalition to reduce secondary instability. The ankle deformity associated with tarsal coalition has a ball and socket configuration. That means that the ankle joint has a cup like tibiofibular socket and correspondingly contoured trochlea tali. This deformity may also be associated with fixed medial inclination of the metatarsal bones, short or fused fibular metatarsals, brachydactyly, and pedal symbrachydactyly. The pathogenesis of that deformity is unclear.9 It is probably a combination of genetic determination and functional adaptation brought about by the greater demand for movement upon this articulation. This demand results from reduced motion in the distal joints with tarsal coalition. Valgus instability of the ankle always seems to accompany the ball and socket ankle joint deformity. The correction of the valgus hindfoot deformity associated with ankle instability is best accomplished with a closing wedge osteotomy of the distal tibia for realignment and with stabilization of the hindfoot (Fig. 4A and 4B). Additional procedures may be considered, including medial sliding a translational calcaneus osteotomy to improve the mechanical axis of the subtalar joint.
Finally, we strongly recommend the use of corrective supramalleolar osteotomy in selected cases of distal tibial or ankle and hindfoot deformities due to peripheral neuropathy. The goal of treatment is to maintain the weightbearing axis of the lower extremity centered over the ankle and subtalar joints. In the presence of deformity, the weightbearing axis can lie medial or lateral to the ankle and subtalar joints. Even with an adequate brace, pressure from prominent bone can cause ulceration. Correction of neuropathic deformity with distal tibia osteotomy is an excellent alternative to a more extensive hindfoot and ankle arthrodesis, particularly in the setting of neuroarthropathy. Wherever possible, correction of neuropathic deformity must be performed with as limited an arthrodesis as possible to prevent loading of adjacent joints. An ankle arthrodesis would therefore be preferable to a tibiotalocalcaneal fusion, which in turn is a better solution than a pantalar arthrodesis. Each deformity must be treated with the appropriate procedure to obtain correction as well as stability. For a supramalleolar deformity, an ankle or tibiotalocalcaneal arthrodesis may be performed but a supramalleolar osteotomy is preferable if the limb can be salvaged. Bear in mind that many of these extended hindfoot arthrodeses must be braced indefinitely. Provided the limb is plantigrade, the need to use an ankle foot orthosis is not a concern
PREOPERATIVE PLANNING
Careful preoperative planning is essential for a successful outcome after distal tibial osteotomy. The patients should have bilateral, full-length weightbearing radiographs of the tibia including the knee and ankle joints. A line is drawn representing the tibial mechanical axis (which in the case of the tibia coincides with the anatomic axis), and another line is drawn to represent the distal tibial articular surface. On the anteroposterior view, the angle formed by these lines is the tibioplafond angle (Fig. 1A). On the lateral view, these lines form the lateral tibial articular angle. Normal TAS and TLS average 93 and 80°, respectively.12 Ideally the appropriate TAS and TLS angles can be determined using radiographs of the healthy contralateral limb. Planning the reconstructive procedure, the surgeon should aim to bring TAS and TLS back to normal values, perhaps adding a few degrees for slight overcorrection to anticipate for some subsidence after the osteotomy.27
Leg lengths should also be determined to anticipate any substantial discrepancy, which will have an impact the choice of osteotomy. The opening wedge osteotomy has the advantage of avoiding leg shortening, but there is a risk of delayed union or nonunion and morbidity after harvest of tricortical bone graft. The leg length change may not seem significant if only 1 cm of shortening is performed with the wedge resection osteotomy, but this becomes significant if an opening wedge osteotomy is performed with a 1-cm graft, with the height differential is almost 2cm once healed. If there are skin related problems (previous incisions with scar formation, infection), low potential of healing, and vascular compromise, the surgeon should avoid this technique. Takakura27 has reported that opening wedge osteotomy produces more rapid bone union than closing wedge osteotomy even though it requires bone grafting.
Although there have been reports of dome osteotomies6,11 and the use of limited skin incisions, corticotomy, and application of ring external fixation frames,18,19 most orthopaedic surgeons are not familiar with these techniques. The most frequently described techniques of distal tibial osteotomy, and the ones which we routinely use, are the closing and opening wedge.7,8,18,19,21,26,27 Using these techniques, the surgeon is able to correct deformities in the coronal and the sagittal plane and can also use wedge modifications to correct biplanar deformities. For example, a recurvatum-varus deformity can be corrected either with a posterolaterally based closing wedge osteotomy or with an anteromedially based opening wedge osteotomy.
The closing wedge has the major disadvantage of limb shortening and does not promote quicker bone healing27, although in our experience the closing wedge osteotomy heals far more rapidly than other osteotomies. The advantage of the closing wedge osteotomy is that it does not require interpositional graft. Also, by preserving leg length, this procedure reduces the risk of decreased strength.
The size of the wedge can be determined by drawing the desired correction angle on the preoperative radiographs and measuring the wedge size on a template, taking magnification into account.2 Alternatively, as described by Canale and Harper,3 the surgeon uses a mathematical formula in which the wedge size is equal to the diameter of the bone at the osteotomy level multiplied by the tangent of the correction angle. This method is accurate and predictable. In this method, 1 mm of bone resection is equal to approximately 1° of angular correction, provided that the bone diameter at the osteotomy level is 5 to 6 cm.3
In the presence of deformity with or without altered TAS and TLS, the surgeon should next determine the center of rotation (CORA) of the deformity.19,20 The CORA is located at the intersection of two lines which represent the mechanical axes of the proximal and distal segments. In cases with isolated angular deformity, the CORA is at the apex of the deformity (Fig. 1A). When translation deformity is also present, the CORA is located above the level of the deformity. In cases of very distal tibial deformities, the CORA is at the level of the ankle joint line. In cases of equinus deformity (malunion) after an ankle fusion, the CORA is at the intersection of the mechanical axis of the tibia and the line through the ankle center of rotation. In such a case the CORA is the level of the lateral process of the talus.19
A closing or opening wedge osteotomy at the level of the CORA will lead to complete realignment of the foot and ankle. If the osteotomy is made proximal or distal to the CORA, the center of the ankle will translate relative to the mechanical axis of the tibia, creating an unnecessary shift of loads and a clinically obvious zig-zag deformity. To avoid creating a secondary translational deformity when the osteotomy is intentionally made at a different level than the CORA, the osteotomy line should be translated as well as angulated. These osteotomy rules apply irrespective of the method of fixation chosen,18-20 as with correction of an equinus malunion of an ankle arthrodesis. In this deformity, the position of the forefoot is fixed relative to the axis of the tibia. The simplest (but not the correct) method of correction is to remove an anterior based wedge from the distal tibia and close the osteotomy while maintaining the posterior cortex intact as a greenstick type of maneuver. The problem with this type of correction is that the foot has been translated anteriorly relative to the tibia, and the mechanical limb axis is no longer aligned or efficient for ambulation with this position of the foot.
The next step in preoperative planning is to determine the extent of compensation that can be achieved by the ankle and subtalar joints after correction. Deformities in the coronal plane are well compensated for by the subtalar joint, and deformities in the sagittal plane are compensated for by the ankle joint. For example, a varus deformity of the tibia is compensated for by eversion of the subtalar joint. In cases of chronic deformity, this attempt to compensate and maintain the foot plantigrade may become permanent if the subtalar joint becomes stiff. Adaptive changes begin to occur in the rest of the foot including the transverse tarsal joint, and a flexible deformity becomes a more rigid deformity. This is important to recognize before the bone correction, or the foot will end up in a nonplantigrade position after full correction of the distal tibial deformity. If a ring fixator is used for correction, the contracted joint can be addressed by distraction at the same time as the osteotomy is performed.18,19 However, this is not always possible, especially in cases with a severely contracted subtalar joint. One may have to undercorrect the bone deformity to bring the foot into a plantigrade position, which is not an adequate solution. We prefer to correct the tibia into the desired position and then to maintain the foot plantigrade using a biplanar calcaneal osteotomy. It might be argued that the obliquity of the subtalar joint after such a calcaneal osteotomy will lead to stresses during weightbearing that may accelerate degeneration. This point is open to debate, but our premise is that a horizontal ankle joint with a plantigrade foot is preferable to ankle joint obliquity with a plantigrade foot through a well aligned but stiff subtalar joint.
The final step is to determine the stabilization technique. The surgeon should aim for a rigid fixation to enhance stability and healing potential. Recent reports have noted the use of staples, external fixation frames, Kirschner wires, screws alone, or plates and screws.6-8,18,19,21,26,27 The decision of the type of the fixation should be made on advance, taking into account the surgeon’s experience, the condition of the skin (previous incisions, infection), the need for translation and rotation correction, and the available bone stock.
SURGICAL TECHNIQUE
Depending on the deformity, the presence of leg length discrepancy, and other factors discussed previously, an opening or closing wedge osteotomy always accomplished with rigid internal fixation is our preferred method. For the correction of a varus deformity of the tibia or a varus tibiotalar joint, we prefer a medial opening wedge osteotomy and we use an anteromedial and a small lateral approach (for the fibular osteotomy). The choice of which cut to make first is a matter of preference, but leaving the fibula intact provides some stability while completing the tibial cut. In cases where the deformity is minimal and the opening wedge is not anticipated to affect the mechanical axis, a greenstick cut of the tibia is made in anticipation of the possibility that a fibular osteotomy may not need to be performed. This step markedly increases the stability of the cut, and the tibia can be opened with a lamina spreader to the desired amount. With this method the tibia does not move around after the cut is made, which may compromise stability. This is generally the method we prefer when a uniplanar correction is performed.
If the osteotomy is performed to correct deformity, it would be ideally located at the level of the CORA.20 In cases of distal tibial deformities where the CORA is at the ankle joint level or in cases without substantial angular deformity of the tibia (idiopathic or posttraumatic arthritis), the osteotomy is performed 4-5 cm proximal to the medial malleolar tip. Once the skin incision is made, minimal periosteal stripping is performed only to the extent needed to complete the osteotomy. The cut on the tibia should ideally be in metaphyseal bone and have secure fixation. We apply the selected periarticular plate to the distal tibia and ensure that there is sufficient space maintained to obtain fixation with three screws distally. We then mark and complete the osteotomy.
Keeping periosteal stripping to a minimum, a horizontal cut is made to the tibia utilizing a broad oscillating saw, preserving the opposite cortex and periosteal sleeve to act as a fulcrum for the opening wedge and to enhance stability. If translation and rotation are necessary (the osteotomy is performed distal or proximal to the CORA), then the opposite cortex is cut completely to allow the distal segment to move. The fibular osteotomy is performed, using the lateral incision at the same level with tibial osteotomy. There have been reports for wedge osteotomies of the fibula8,27 but we have not found this necessary because correction can be achieved using an oblique fibula corticotomy. If there is marked angular deformity, a wedge osteotomy of the fibula is performed at the apex of the fibula deformity.7 Then the tibial osteotomy is gently distracted using a lamina spreader, and the space is filled with an appropriate shaped bone graft.
The graft alternatives are to harvest it from the ipsilateral iliac crest,26,27 or to use tricortical allograft. The two basic types of bone grafts are structural and cancellous. A structural bone graft is one that alters the shape during a reconstruction procedure by virtue of its size and dimension. In our institution, we use a tricortical or bicortical graft to alter the height, width, or dimension of a part of the foot or the tibial mechanical axis, as, for example, in subtalar distraction bone block arthrodesis and interposition graft hallux metatarsophalangeal joint fusion.16 The structural bone graft provides immediate mechanical support, with little likelihood of collapse even after resorption which occurs during revascularization. Some structural integrity remains during the process of bone graft incorporation to allow the graft to withstand loads. We have obtained structural autografts from the iliac crest, the proximal tibia, and the fibula, but recently have successfully used allograft sources for structural grafting, including the femoral head. The femoral head can be harvested at different parts of the bone to function as unicortical or multicortical graft. The advantage of such a graft is the lack of morbidity from harvesting an autograft, and although its incorporation is slower than that of cancellous graft, it occurs nonetheless.16 A two-plane deformity is addressed by modifying the wedge shape. After the deformity has been corrected, the osteotomy is provisionally fixed with K-wires away from where the definitive fixation will go. The alignment is assessed using fluoroscopy.
There have been reports where external fixation frames, staples, K-wires, screws alone, or plates and screws6-8,18,19,21,26,27 have been used for the osteotomy fixation. Whenever possible, we use plate and screws fixation. We have found that the periarticular titanium plates (Ace DePuy, Warsaw, IN) provide excellent stability by permitting the insertion of three screws in the distal segment (Fig. 5). Fixation of the fibula is controversial.2,7,27 We do not routinely secure the fibula at all, although a plate or screws may be used after a wedge osteotomy on the fibula has been performed.
Leg length should be preserved whenever possible, which supports use of the opening wedge technique. If there are potential problems with skin healing and limb perfusion, then the closing wedge technique is utilized. In such a case a varus deformity is corrected with a lateral closed wedge osteotomy through a single lateral approach over the fibula. After the lateral part of the tibia has been exposed and the osteotomy level has been determined, a K-wire is inserted to the tibia perpendicular to the mechanical axis. A second K-wire is inserted parallel to the ankle joint line intersecting with the first K-wire, ideally at the apex of the deformity. Pin position is then checked with fluoroscopy, and if position is satisfactory, the pins can be used as a guide to make the tibial cuts (Fig. 6). There is no reason for a medial incision because the tibia can be fixed with percutaneous cannulated screws. Here we use a plate to secure the fibula and to increase stability laterally.
Postoperative care depends on the stability of the fixation, but in general we prefer to protect the osteotomy in a short leg non-weightbearing cast until we have radiographic evidence of healing, which occurs between 10 and 14 weeks.
SUMMARY
The distal tibial (supramalleolar) osteotomy for the treatment of pathologic entities of the adult distal tibia and foot and ankle has received limited attention in the literature. It is technically demanding and requires an extensive and careful preoperative planning. In our experience, it has been proved a useful tool in the surgical armamentarium to reconstruct the normal mechanical environment in malunion preventing any long term deleterious effects and to shift and redistribute loads in the ankle joint to protect the articular cartilage from further degeneration.
REFERENCES
1. Abraham E, Lubicky JP, Songer MN, et al: Supramalleolar osteotomy for ankle valgus in myelomeningocele. J Pediatr Orthop 16:774, 1996
2. Acevedo JI, Myerson MS: Reconstructive alternatives for ankle arthritis. Foot Ankle Clin 4:409, 1999
3. Canale ST, Harper MC: Biotrigonometric analysis and practical applications of osteotomies of tibia in children. Instr Course Lect 30:85, 1981
4. Coester LM, Saltzman CL, Leupold J, et al: Long-term results following ankle arthrodesis for post-traumatic arthritis. J Bone Joint Surg 83A:219, 2001
5. Coughlin MJ, Mann RA: Arthrodesis of the foot and ankle. In Myerson MS (ed): Surgery of the Foot and Ankle, ed. 7. St.Louis, Mosby, 1999, p 651
6. Graehl PM, Hersh MR, Heckman JD: Supramalleolar osteotomy for the treatment of symptomatic tibial malunion. J Orthop Trauma 1:281, 1987
7. Hall RL: The use of osteotomy to correct foot and ankle disorders. In Myerson MS (ed): Foot and Ankle Disorders, Philadelphia, WB Saunders Co, 2000, p 999
8. Heywood AW: Supramalleolar osteotomy in the management of the rheumatoid hindfoot. Clin Orthop 177:76, 1983
9. Kelikian H, Kelikian A: The ankle in complex disorders. In Kelikian H, Kelikian A (eds): Disorders of the Ankle, Philadelphia, WB Saunders Co, 1985, p 810
10. Kristensen KD, Kiaer T, Blicher J: No arthrosis of the ankle 20 years after malaligned tibial-shaft fracture. Acta Orthop Scand 60:208, 1989
11. Kumar SJ, Keret D, MacEwen GD: Corrective cosmetic supramalleolar osteotomy for valgus deformity of the ankle joint: a report of two cases. J Pediatr Orthop 10:124, 1990
12. Mangone PG: Distal tibial osteotomies for the treatment of foot and ankle disorders. Foot Ankle Clin 6:583, 2001
13. McKellop HA, Llinas A, Sarmiento A: Effects of tibial malalignment on the knee and ankle. Orthop Clin North Am 25:415, 1994
14. McNicol D, Leong JC, Hsu LC: Supramalleolar derotation osteotomy for lateral tibial torsion and associated equinovarus deformity of the foot. J Bone Joint Surg 65A:166, 1983
15. Merchant TC, Dietz FR: Long-term follow-up after fractures of the tibial and fibular shafts. J Bone Joint Surg 71A:599, 1989
16. Myerson MS: Principles of foot and ankle surgery. In Myerson MS (ed): Foot and Ankle Disorders, Philadelphia, WB Saunders Co, 2000, p 1
17. Napiontek M, Nazar J: Tibial osteotomy as a salvage procedure in the treatment of congenital talipes equinovarus. J Pediatr Orthop 14:763, 1994
18. Paley D: The correction of complex foot deformities using Ilizarov's distraction osteotomies. Clin Orthop 293:97, 1993
19. Paley D, Herzenberg JE: Applications of external fixation to foot and ankle reconstruction. In Myerson MS (ed): Foot and Ankle Disorders, Philadelphia, WB Saunders Co, 2000, p 1135
20. Paley D, Herzenberg JE, Tetsworth K, et al: Deformity planning for frontal and sagittal plane corrective osteotomies. Orthop Clin North Am 25:425, 1994
21. Pearce MS, Smith MA, Savidge GF: Supramalleolar tibial osteotomy for haemophilic arthropathy of the ankle. J Bone Joint Surg 76B:947, 1994
22. Sammarco GJ: Biomechanics of the foot. In Basic Biomechanics of the Muskuloskeletal System, ed. 2. Philadelphia, Lea & Febiger, 1989, p 163
23. Scheffer MM, Peterson HA: Opening-wedge osteotomy for angular deformities of long bones in children. J Bone Joint Surg 76A:325, 1994
24. Steffensmeier SJ, Saltzman CL, Berbaum KS, et al: Effects of medial and lateral displacement calcaneal osteotomies on tibiotalar joint contact stresses. J Orthop Res 14:980, 1996
25. Stevens PM, Otis S: Ankle valgus and clubfeet. J Pediatr Orthop 19:515, 1999
26. Takakura Y, Takaoka T, Tanaka Y, et al: Results of opening-wedge osteotomy for the treatment of a post-traumatic varus deformity of the ankle. J Bone Joint Surg 80A:213, 1998
27. Takakura Y, Tanaka Y, Kumai T, et al: Low tibial osteotomy for osteoarthritis of the ankle. Results of a new operation in 18 patients. J Bone Joint Surg 77B:50, 1995
28. Tarr RR, Resnick CT, Wagner KS, et al: Changes in tibiotalar joint contact areas following experimentally induced tibial angular deformities. Clin Orthop 199:72, 1985
29. Ting AJ, Tarr RR, Sarmiento A, et al: The role of subtalar motion and ankle contact pressure changes from angular deformities of the tibia. Foot Ankle 7:290, 1987
30. Whitesides TE, Haney TC, Morimoto K, et al: Tissue pressure measurements as a determinant for the need of fasciotomy. Clin Orthop 113:43, 1975
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