Emmanouil D. Stamatis
DEFINITION
Ankle arthritis is characterized by loss of joint cartilage and joint narrowing.
Primary ankle arthritis is relatively rare; most commonly, ankle arthritis is posttraumatic in origin. Inflammatory arthritides may also involve the ankle. While ankle arthrodesis and total ankle arthroplasty are accepted surgical treatments for advanced ankle arthritis, joint-preserving supramalleolar osteotomy is an attractive alternative in select patients with advanced ankle arthritis, particularly in ankle arthritis associated with malalignment.
Supramalleolar osteotomy, whether opening or closing wedge, redistributes stresses on the ankle, transferring weight from an overloaded arthritic portion of the joint to a healthier aspect of the joint.6,24,29 In theory, realignment also improves the biomechanics of the lower extremity28 and may improve function and delay the progression of the degenerative process.
ANATOMY
The ankle joint is the articulation formed by the mortise (tibial plafond–medial malleolus and the distal part of the fibula) and the talus.
The ankle is a modified hinge joint with a slight oblique orientation in two planes: (a) posterior and lateral in the transverse plane and (b) lateral and downward in the coronal plane.
This sagittal plane orientation affords about 6 degrees of rotation and 45 to 70 degrees in the flexion–extension motion arc.
The tibiotalar joint functions as part of the ankle–subtalar joint complex during gait; portions of the medial and lateral collateral ligaments cross both the ankle and subtalar joints. The blood supply is provided by the anterior and posterior tibial arteries and the peroneal artery as well as their branches and anastomoses, forming a rich vascular ring.
The distal tibial plafond is slightly valgus oriented, in the coronal plane, with respect to the tibial diaphysis, forming an angle called the tibial–angle surface (TAS) with a value of 93 degrees.12
The same angle in the sagittal plane, with its apex posteriorly, is called the tibial–lateral surface (TLS), with a value of 80 degrees.12
PATHOGENESIS
Idiopathic (primary) arthritis, or osteoarthrosis, is relatively rare in the ankle. The exact mechanism of cartilage degeneration and loss has not been clearly defined, although several theories have been proposed.
Secondary arthritic involvement is mainly posttraumatic, occurring after intra-articular fractures, chondral or osteochondral injuries, and chronic instability.
Other causes of ankle arthritis include peripheral neuropathy (neuroarthropathy) and various inflammatory disorders (such as rheumatoid arthritis, mixed connective tissue disorders, gout, and pseudogout), primary synovial disorders (pigmented villonodular synovitis), and septic arthritis, as well as seronegative arthritides associated with psoriasis, Reiter syndrome, and spondyloarthropathy.
Distal tibial deformity may be a result of malunion of a distal tibial or pilon fracture, physeal disturbance from adjacent osteochondromata, physeal dysplasia, and so forth.
NATURAL HISTORY
Untreated ankle arthritis typically progresses, with worsening pain that eventually interferes with daily activities. Gradually, ankle stiffness in addition to pain leads to a disturbance of physiologic heel-to-toe gait.
Low-demand patients with isolated ankle arthritis may function surprisingly well because of the adaptive effect of the healthy subtalar and transverse talar joints. However, obesity, high-demand activity levels, and concomitant subtalar or transverse tarsal joint pathology typically contribute to the morbidity of ankle arthritis.
To our knowledge there are no absolute numbers for tibiotalar angular alignment that predispose an ankle to the development of arthritis. Several authors have reported that angulation exceeding 10 degrees was compatible with long-term normal function and absence of pain in the ankle joint,9,14 while biomechanical studies on cadavers have shown that there is a decrease of the contact surface area in the ankle joint of up to 40% in the presence of malalignment,31,32 with the distal tibial deformities significantly altering total tibiotalar contact area, contact shape, and contact location.31
PATIENT HISTORY AND PHYSICAL FINDINGS
A complete examination of the ankle and hindfoot joints should include the following:
Soft tissue condition: previous scars, callosities, ulcers, fistulas, and so forth
Vascular status: peripheral pulses, microcirculation (capillary refill), ankle–brachial index
Sensation: light touch and, if indicated, SemmesWeinstein monofilament testing to rule out a peripheral neuropathy. A joint-preserving realignment supramalleolar osteotomy is feasible in select patients with peripheral neuropathy, but the potential for Charcot neuroarthropathy and failure of the procedure must be considered.
Stability: Anterior drawer test and inversion and eversion stress evaluation are performed to evaluate the integrity of the ankle and hindfoot ligaments. Realignment osteotomy with unstable or incompetent ankle or hindfoot ligaments may fail to improve function.
Motor strength: Manual motor testing of the major muscle groups is performed. Realignment in patients lacking essential motor function at the ankle will improve function in stance phase but will typically necessitate bracing for effective gait.
Alignment: The angle made by the Achilles and the vertical axis of the calcaneus is normally 5 to 7 degrees of valgus. Altered alignment to varus or increased valgus position indicates either abnormal tilt of the talus within the ankle mortise (eg, unicompartmental cartilage wear) or abnormality of the subtalar joint.
Effusion testing: Elimination or fullness of the gutters indicates intra-articular fluid accumulation or hypertrophied capsular tissue.
Normal ankle and hindfoot range of motion (ROM) in the sagittal plane is 20 degrees of dorsiflexion to 50 degrees of plantarflexion. Normal values of hindfoot motion are difficult to measure, since the motion is triplanar. A reasonable reference is 5 degrees of eversion and 20 degrees of inversion.
Isolated supramalleolar osteotomy for a stiff ankle rarely improves ROM; a stiff, diffusely arthritic and malaligned ankle may be best treated with realignment.
Hindfoot stiffness must also be documented. In patients with malaligned ankles, the hindfoot compensates. For example, a varus ankle will generally be associated with a compensating hindfoot in excessive valgus. If the hindfoot has lost its flexibility due to longstanding compensation for ankle malalignment, then supramalleolar osteotomy may realign the tibiotalar joint but create hindfoot malalignment. With a flexible hindfoot, this is generally not a problem.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Weight-bearing AP, lateral, and mortise ankle and foot radiographs determine the extent of arthritic involvement, deformity, bone defects in the distal tibial plafond or talus, and the presence of arthritis in the adjacent hindfoot articulations. Radiographs may also suggest avascular necrosis (AVN) of the talus or distal tibia.
With deformity, a minimum of full-length, weight-bearing AP and lateral tibial radiographs must be obtained. If more proximal deformity is suspected, then mechanical axis, fulllength hip-to-ankle radiographs should be considered to accurately plan realignment. More comprehensive full-length weight-bearing radiographs are required to measure the TAS and TLS angles, the level of center of rotation of angulation (CORA) in case of existing deformity, and the preoperative leg-length discrepancy, since any substantial discrepancy may have an impact to the choice of osteotomy.
Diagnostic injection. If there is uncertainty over whether the pain is originating from the ankle or hindfoot, selective injections may be of use in distinguishing the source of pain.
DIFFERENTIAL DIAGNOSIS
Bone marrow edema
Soft tissue pathology
Distal tibial plafond or talar AVN
Osteochondritis
NONOPERATIVE MANAGEMENT
Nonoperative treatment of ankle arthritis includes pharmacologic agents, intra-articular corticosteroid injections, shoe wear modifications, and orthoses.
Nonsteroidal anti-inflammatory agents (NSAIDs) are widely used and have proven efficacy in the management of arthritis, including ankle arthritis. In select patients with gastrointestinal irrigation, COX-2 inhibitors may offer a reasonable alternative to NSAIDs. Inflammatory arthritides are managed with immunosuppressive agents.
Judicious use of intra-articular corticosteroid injections may temporize inflammation associated with intra-articular ankle pathology. Moreover, initial injections of the ankle or hindfoot may serve a diagnostic purpose to distinguish ankle from hindfoot pain. Indiscreet use of corticosteroid injections may have a deleterious effect on the residual joint cartilage as a result of the steroid, the anesthetic, or perhaps the accompanying preservative.
Bracing to immobilize and support the arthritic ankle may provide some pain relief with weight bearing and ambulation. Specifically, polypropylene ankle–foot orthoses (AFOs), double-metal upright braces, and lace-up braces, combined with the use of a stiff-soled rocker-bottom shoe, may be of benefit. Bracing tibial and tibiotalar malalignment is challenging. With a flexible hindfoot, some axial realignment may be feasible, but correction is generally not possible at the focus of deformity.
SURGICAL MANAGEMENT
We use the supramalleolar osteotomy for the following indications25:
Realignment of distal tibia fracture malunion without or with mild osteoarthritic changes of the ankle joint
Realignment of distal tibia malunion with mild to moderate osteoarthritic changes of the ankle joint
Ankle fusion malunion
Ankle arthritis with deformity secondary to intra-articular trauma or AVN of the distal tibia
Correction of valgus deformity associated with a balland-socket ankle joint configuration secondary to tarsal coalition
Tibiotalar osteoarthritis resulting from chronic lateral ankle instability or a cavovarus foot deformity
Restoration of a plantigrade foot position in ankle deformity resulting from Charcot neuroarthropathy, to create ankle and hindfoot alignment that may be safely braced
Correction of limb alignment in adolescents and young adults due to growth plate injury
Correction of lower limb alignment as staged planning for a total ankle replacement
As a rule, we reserve supramalleolar osteotomy using internal fixation for mild to moderate angular deformities in the coronal or the sagittal plane. Severe angular deformities with concomitant translation of the distal segment or shortening are, in our opinion, better managed using external fixation and the principles of Ilizarov. Moreover, gradual correction of severe deformity with formation of a regenerate avoids large plates under a wound and typically thin soft tissues that would be under tension with acute correction using internal fixation.
Comparing closingand opening-wedge supramalleolar osteotomies: A closing-wedge osteotomy may result in limb shortening when compared to opening-wedge osteotomies. Conflicting reports exist regarding healing rates between the two methods. Studies suggest that closing-wedge osteotomies exhibit delayed healing when compared to opening-wedge osteotomies,28 but other reports demonstrate more rapid healing using a closing-wedge osteotomy.24–26 One advantage of a closing-wedge osteotomy is that it does not necessitate incorporation of cancellous or structural interpositional graft. While an opening-wedge osteotomy may preserve limb length, resultant skin tension from acute correction may create problems with wound healing and potential vascular compromise if the vessels are put on sudden stretch. Gradual correction with external fixation may be a safer option in cases with severe deformity.
In the absence of appreciable preoperative leg-length discrepancy, we recommend correcting distal tibial varus deformities with a medial opening-wedge osteotomy and valgus deformities with a medial closing-wedge osteotomy.
Preoperative Planning
We routinely obtain bilateral, full-length weight-bearing radiographs of the tibia including the knee and ankle joints.
We draw two lines on the preoperative radiographs: (a) the tibial mechanical axis (which for the tibia coincides with the anatomic axis) and (b) the distal tibial articular surface. On the AP view, the angle formed by these lines is the TAS angle (FIG 1). On the lateral view, these lines form the TLS angle.
Ideally, we define the physiologic TAS and TLS angles for each patient using radiographs of the healthy contralateral limb. The goal of surgery is to realign the TAS and TLS to physiologic values and perhaps add a few degrees of (slight) overcorrection, to compensate for anticipated minor subsidence during healing of the osteotomy.
The full-length weight-bearing radiographs serve to determine preoperative leg-length discrepancy, which may influence the choice between openingand closing-wedge osteotomies.
FIG 1 • Preoperative AP radiograph of a patient with severe valgus malalignment of the distal tibia, due to physeal disturbance from adjacent osteochondroma that was excised in a previous procedure. Note the location of center of rotation of angulation (CORA) at the intersection of two lines that represent the mechanical axes of the proximal (line A) and distal segments (line B). Line A, also representing the tibial mechanical axis (which in the case of the tibia coincides with the anatomic axis), and another line that is drawn to represent the distal tibial articular surface form the tibial–ankle surface (TAS) angle on the AP view with a magnitude of 108 degrees.
Determining the CORA of the deformity (Fig. 1): The CORA is the intersection of the two lines that define the deformity, lines that are drawn to represent the mechanical axes of the proximal (line A) and distal segments (line B).
With isolated angular deformity, the CORA is at the apex of the deformity. When translation is also present, the CORA is located proximal to of the deformity.
In very distal tibial deformities or ankle deformities with minor to moderate alterations of the TAS angle, the CORA is at the level of the ankle joint line.
With distal tibial procurvatum deformity (malunion) or ankle fusion malunion in equinus, the CORA is the intersection of the tibial mechanical axis and a line representing the ankle's center of rotation. Typically, in such cases, the CORA is the level of the lateral process of the talus.
Significance of the CORA: An osteotomy made at the level of the CORA, whether closing or opening, will predictably realign the ankle without translation of the distal segment and center of the ankle. If the osteotomy is not performed at the CORA, the center of the ankle will translate relative to the mechanical axis of the tibia, creating undesirable malalignment of the two segments and an unnecessary shift of loads to the ankle joint. To avoid secondary translational deformity when the osteotomy is intentionally made at a different level than the CORA, the distal segment must be translated relative to the proximal segment. These osteotomy rules apply irrespective of the method of fixation chosen.19,20
The size of the opening-wedge or closing-wedge resection 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.1
The final step in preoperative planning is to determine the extent of compensation that is achieved by the subtalar joint before correction of the deformity. Deformities in the coronal plane are well compensated for by the subtalar joint, unless there is preoperative stiffness in the hindfoot.
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 fixed at the subtalar joint. Moreover, other adaptive changes may occur including the transverse tarsal joint or midfoot, creating a fixed forefoot deformity. These secondary fixed deformities may also require surgical correction after the ankle is realigned in order to create a functional, plantigrade foot.
Positioning
The supramalleolar osteotomy is performed with the patient supine.
A bump under the ipsilateral hip prevents the natural tendency of the lower extremity to fall into external rotation.
Approach
The fibular osteotomy is performed first, using a small lateral incision, protecting the lateral branch of the superficial peroneal nerve.
For the supramalleolar osteotomy, a medial skin incision is made and periosteal elevation is performed only to the extent needed to perform the osteotomy.
TECHNIQUES
MEDIAL CLOSING-WEDGE SUPRAMALLEOLAR OSTEOTOMY
Perform the fibular osteotomy first, using a small lateral incision. The osteotomy is oblique, located at the same level with the planned tibial cut. Some surgeons prefer to make the fibular osteotomy at a different level from the supramalleolar osteotomy.
We do not routinely apply fixation to the fibular osteotomy, except in cases where it is felt that additional stability is required.
When correcting tibial deformity, perform the osteotomy at the CORA (TECH FIG 1).
In select cases, the supramalleolar osteotomy is not performed at the CORA. In some distal tibial deformities, the CORA may be located at the ankle joint, where the osteotomy is not feasible, and the translational component must be compensated. Also, in ankle deformity with only minor alterations of the TAS angle and when detrimental translation of the distal fragment is not a major concern, we generally perform the osteotomy 4 to 5 cm proximal to the medial malleolar tip.
We routinely use Kirschner wires to define our proposed osteotomy; for an opening-wedge osteotomy we use a single Kirschner wire, but for the medial closing-wedge osteotomy, two Kirschner wires are required to define the tibial wedge resection. Under fluoroscopic guidance, insert the first Kirschner wire perpendicular to the mechanical axis and the second parallel to the ankle joint, intersecting the first Kirschner wire at the apex of the deformity. The size of the wedge has been determined during the preoperative planning, and the Kirschner wires are positioned 1 to 2 mm wider than the proposed osteotomy, so they can be left in place as a guide for the saw cuts. While the Kirschner wires define the osteotomy in one plane, the surgeon must also orient the saw blade perpendicular to the tibial shaft axis when performing the osteotomy. With the anterior and posterior soft tissue and neurovascular structures protected, we routinely use a broad oscillating saw, constantly irrigating the blade with cooled sterile saline or water to limit osteonecrosis. Ideally, a thin cortical bridge and periosteal sleeve on the opposite cortex will be preserved, to allow for a greenstick-like closure of the osteotomy that facilitates maintenance of alignment and enhances stability. However, when the osteotomy is intentionally performed at a level different than that of CORA, then the opposite cortex must be violated to allow the distal segment to be translated.
TECH FIG 1 • Medial closing-wedge supramalleolar osteotomy. A. Using a preoperative radiograph the center of rotation of angulation (CORA) is located at the intersection of two lines that represent the mechanical axes of the proximal and distal segments. B. Under fluoroscopy a Kirschner wire is inserted to the tibia perpendicular to the mechanical axis and a second Kirschner wire is inserted parallel to the ankle joint line intersecting the first wire, ideally at the apex of the deformity. C, D. Guide pin wires used to perform a closing medial wedge osteotomy. Pin A has been inserted to the tibia perpendicular to the mechanical axis and pin B has been inserted parallel to the ankle joint line, intersecting pin A at the apex of the deformity. E. The cut wedge. The pins have been used as a guide for the tibial cuts, while the size of the wedge has been determined during the preoperative planning. F. Fluoroscopic view of the resected wedge. G. Fluoroscopic view of the closed osteotomy. H, I. Fluoroscopic AP and lateral views of the provisionally fixed osteotomy with Kirschner wires. J. Photo of the applied periarticular plate. Note the excellent fit on the distal tibia. K. The applied periarticular plate after completion of fixation with three screws in the distal segment. L. Fluoroscopic view of the osteotomy after completion of fixation.
After removing the resected wedge and performing appropriate translation of the distal segment, close the osteotomy and provisionally fix it with Kirschner wires. The provisional fixation may be guidewires for intended cannulated screws or it must be positioned so as not to interfere with the definitive fixation. Assess alignment of the tibia and ankle fluoroscopically, both in the AP and lateral planes.
Several dedicated low-profile periarticular plating systems for the distal tibia are marketed, both locking and nonlocking. The majority of these plates were designed for the contours of the physiologic tibia. With a wedge resection the fit is typically acceptable but may not be perfect. Locking plates may provide optimal stability, but if the osteotomy is not fully closed, these may in fact delay or even hinder healing. Nonlocking plates, in our opinion, allow for a small amount of settling at the osteotomy with weight bearing, potentially facilitating healing. (If additional stability is required, then cannulated or solid screws may be used from the tip of the medial malleolus across the osteotomy. Alternatively, a second plate may be added anteriorly on the tibia to provide rotational control to the tibia; however, this requires greater soft tissue dissection.)
We do not routinely apply fixation to the fibula, but if additional stability is required, then we apply a lowprofile fibular plate.
Final fluoroscopic images in the AP and lateral planes confirm proper alignment, apposition of the osteotomy, and position of hardware.
MEDIAL OPENING-WEDGE SUPRAMALLEOLAR OSTEOTOMY
Again, the osteotomy is ideally located at the level of the CORA (TECH FIG 2). If the CORA is located at the ankle joint level or if only minor correction is required and translation of the distal segment is of little concern, then we perform the osteotomy 4 to 5 cm proximal to the medial malleolar tip.
We perform either a horizontal or slightly oblique (proximal medial to distal lateral) tibial osteotomy with a broad oscillating saw, preserving the opposite cortex and periosteal sleeve to serve as a fulcrum for the opening wedge and to enhance stability. If translation is necessary (the osteotomy is intentionally performed at a level different than that of CORA), then the opposite cortex is cut completely to allow the distal segment to move.
Under fluoroscopy, gently distract the tibial osteotomy using a lamina spreader or alternative distraction system until desired correction is achieved.
We routinely use contoured structural graft (generally the neck portion of a femoral head allograft) to fill the osteotomy.
After correcting the deformity, provisionally fix the osteotomy with Kirschner wires in a manner that does not interfere with the definitive fixation. Assess the alignment using fluoroscopy, both in the AP and lateral planes.
Several dedicated low-profile periarticular plating systems for the distal tibia are marketed, both locking and nonlocking. The majority of these plates were designed for the contours of the physiologic tibia. With an openingwedge osteotomy the fit is typically acceptable but may not be perfect. Locking plates may provide optimal stability, but if the osteotomy is not fully closed, these may in fact delay or even hinder healing. Nonlocking plates, in our opinion, allow for a small amount of settling at the osteotomy with weight bearing, potentially facilitating incorporation of the interpositional graft. (If additional stability is required, then cannulated or solid screws may be used from the tip of the medial malleolus across the osteotomy. Alternatively, a second plate may be added anteriorly on the tibia to provide rotational control to the tibia; however, this requires greater soft tissue dissection.)
TECH FIG 2 • Medial opening-wedge supramalleolar osteotomy. A. Using a preoperative radiograph the center of rotation of angulation (CORA) is located at the intersection of two lines that represent the mechanical axes of the proximal and distal segments. B. Under fluoroscopy a Kirschner wire is used to mark the osteotomy site at the CORA level. C, D. Under fluoroscopy the tibial osteotomy is gently distracted using a lamina spreader until desired correction is achieved. (A, C, D: from Myerson MS. Reconstructive Foot and Ankle Surgery. Philadelphia: Elsevier; 205:254.
WOUND CLOSURE
After completing the fixation, close the wound routinely in layers. With opening-wedge osteotomies, the skin tension is typically greater than before surgery, but with longitudinal incisions, this is rarely problematic. Use of a drain is at the discretion of the surgeon; we do not routinely use a drain.
POSTOPERATIVE CARE
The procedure may be performed on an outpatient basis, but we routinely keep the patient overnight for monitoring and pain control (23-hour observation status).
While rare, a tibial osteotomy, albeit distal to the lower leg muscles, could potentially create a compartment syndrome, and therefore overnight monitoring is prudent. All patients are discharged with a non–weight-bearing postoperative splint, are instructed to maintain elevation of the extremity, and are to return to the clinic 2 weeks after surgery for suture removal.
At 2 weeks we routinely place the patient in a removable, prefabricated cam walker boot. If we have concern for the osteotomy stability or patient compliance, we obtain radiographs at this time to ensure satisfactory alignment and fixation, and place the patient into a short-leg non–weightbearing cast.
The patient returns at 6 weeks from surgery, at which time we routinely obtain simulated weight-bearing radiographs of the ankle. Depending on the stability of fixation and evidence for progression toward healing, we allow the patient to progressively advance weight bearing in the cam walker boot.
Typically, with follow-up at 10 weeks from surgery, full weight bearing is permitted in the cam walker boot, with a rapid transition to a regular shoe, provided that weightbearing radiographs of the ankle suggest satisfactory healing. Early ROM exercises without resistance are initiated early (at 2 weeks), when osteotomy fixation is deemed stable and if there is no concomitant procedure (eg, ligament reconstruction or tendon transfer) dictating adjustment of the rehabilitation protocol.
OUTCOMES
Several studies have shown that the overall outcome of supramalleolar osteotomy is very good in terms of pain relief, correction of any existing mechanical malalignment, and the arresting of arthritic changes in the ankle joint.6,24,28,29
The type of osteotomy (opening vs. closing wedge) does not influence the final outcome, even though a closing-wedge osteotomy may lead to leg-length discrepancy or decreased strength.24
The type of osteotomy (opening vs. closing wedge) has no influence on the time of osseous healing.24
COMPLICATIONS
Nonunion
Delayed union
Over- or undercorrection of the deformity
Decreased postoperative ROM
Failure to perform the osteotomy at the level of CORA, thus translating the distal fragment and center of the ankle away from the mechanical axis
Failure to perform the appropriate translation of the distal segment, in cases where the osteotomy is intentionally performed at a different level than that of CORA (such as when the CORA is at the level or distal to the ankle joint), leading to mechanical axis shifting
Acknowledgment
I would like to thank my mentor Mark S. Myerson for his enlightening training, friendship, and help for the preparation of this chapter.
REFERENCES
· Acevedo JI, Myerson MS. Reconstructive alternatives for ankle arthritis. Foot Ankle Clin 1999;4:409–430.
· Becker AS, Myerson MS. The indications and technique of supramalleolar osteotomy. Foot Ankle Clin 2009;14:549–561.
· Benthien RA, Myerson MS. Supramalleolar osteotomy for ankle deformity and arthritis. Foot Ankle Clin 2004;9:475–487.
· Borrelli J Jr, Leduc S, Gregush R, et al. Tricortical bone grafts for treatment of malaligned tibias and fibulas. Clin Orthop Relat Res 2009;476:1056–1063.
· Chao KH, Wu CC, Lee CH, et al. Corrective-elongation osteotomy without bone graft for old ankle fracture with residual diastasis. Foot Ankle Int 2004;25:123–127.
· Graehl PM, Hersh MR, Heckman JD. Supramalleolar osteotomy for the treatment of symptomatic tibial malunion. J Orthop Trauma 1987;1:281–292.
· Hintermann B, Knupp M, Barg A. Osteotomies of the distal tibia and hindfoot for ankle realignment [in German]. Orthopaede 2008;37: 212–223.
· Knupp M, Pagenstert G, Valderrabaro V, et al. Osteotomies in varus malalignment of the ankle [in German]. Oper Orthop Traumatol 2008;20:262–273.
· Kristensen KD, Kiaer T, Blicher J. No arthrosis of the ankle 20 years after malaligned tibial-shaft fracture. Acta Orthop Scand 1989;60: 208–209.
· Lee KB, Cho YJ. Oblique supramalleolar opening wedge osteotomy without fibular osteotomy for varus deformity of the ankle. Foot Ankle Int 2009;30:565–567.
· Lee HS, Wapner KL, Park SS, et al. Ligament reconstruction and calcaneal osteotomy for OA of the ankle. Foot Ankle Int 2009;30: 475–480.
· Mangone PG. Distal tibial osteotomies for the treatment of foot and ankle disorders. Foot Ankle Clin 2001;6:583.
· Marti RK, Raaymakers EL, Nolte PA. Malunited ankle fractures. J Bone Joint Surg Br 1990;72B:709–713.
· Merchant TC, Dietz FR. Long-term follow-up after fractures of the tibial and fibular shafts. J Bone Joint Surg Am 1989;71A:599–606.
· Neumann HW, Lieske S, Schenk. Supramalleolar subtractive valgus osteotomy of the tibia in the management of ankle joint degeneration with varus deformity [in German]. Oper Orthop Traum 2007;19: 511–526.
· Pagenstert GI, Hintermann B, Barg A, et al. Realignment surgery as alternative treatment of varus and valgus ankle OA. Clin Orthop Rel Res 2007;462:156–168.
· Pagenstert GI, Leumann A, Hintermann B, et al. Sports and recreation activity of varus and valgus ankle OA before and after realignment surgery. Foot Ankle Int 2008;29:985–993.
· Pagenstert G, Knupp M, Valderrabano V, et al., Realignment surgery for valgus ankle OA. Oper Orthop Traum 2009;21:77–87.
· Paley D. The correction of complex foot deformities using Ilizarov's distraction osteotomies. Clin Orthop Relat Res 1993; 293:97–111.
· Paley D, Herzenberg JE, Tetsworth K, et al. Deformity planning for frontal and sagittal plane corrective osteotomies. Orthop Clin North Am 1994;25:425–465.
· Perena A, Myerson M. Surgical techniques for the reconstruction of malunited ankle fractures. Foot Ankle Clin 2008;13:737–751.
· Rozbruch SR, Fragomen AT, Ilizarov S, et al. Correction of tibial deformity with use of the Ilizarov-Taylor spatial frame. J Bone Joint Surg Am 2006;88:156–174.
· Sinha A, Sirikonda S, Giotakis N, et al. Fibular lengthening for malunited ankle fractures. Foot Ankle Int 2008;29:1136–1140.
· Stamatis ED, Cooper PS, Myerson MS. Supramalleolar osteotomy for the treatment of distal tibial angular deformities and arthritis of the ankle joint. Foot Ankle Int 2003;24:754–764.
· Stamatis ED, Myerson MS. Supramalleolar osteotomy: indications and technique. Foot Ankle Clin 2003;8:317–333.
· Stamatis E, Myerson M. Supramalleolar osteotomy for the treatment of distal tibial angular deformities and arthritis of the ankle joint. Tech Foot Ankle Surg 2004;3:138–142.
· Swords MP, Nemec S. Osteotomy for salvage of the arthritic ankle. Foot Ankle Clin 2007;12:1–13.
· 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 Br 1995;77B:50–54.
· 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 Am 1998;80A:213–218.
· Tanaka Y, Takakura Y, Hayashi K, et al. Low tibial osteotomy for varus-type OA of the ankle. J Bone Joint Surg Br 2006;88B:909–913.
· Tarr RR, Resnick CT, Wagner KS, et al. Changes in tibiotalar joint contact areas following experimentally induced tibial angular deformities. Clin Orthop Relat Res 1985;199:72–80.
· 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 1987;7:290–299.
· Weber D, Friederich NF, Müller W, et al. Lengthening osteotomy of the fibular for post-traumatic malunion: indications, technique and results. Int Orthop 1998;22:149–152.