Posttraumatic osteoarthritis is the

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1 Review Article Distal Fibula Malunions Alice Chu, MD Lon Weiner, MD Abstract Anatomic reduction and fixation of unstable ankle fractures is necessary to prevent posttraumatic arthritis. Malunion of the distal fibula in unstable ankle fractures may lead to progressive talar instability. Ankle fracture malunions often present with concomitant syndesmotic widening, which can cause surgeons to overlook changes in fibula length and rotation. The decision to proceed with surgery should be made only after a careful diagnostic workup and detailed preoperative discussion with the patient. Considerations for surgical management include location and orientation of a corrective osteotomy, use of structural graft, widening of the syndesmosis, assessment of reduction, and the need for medial exposure. Good and excellent clinical results after fibular reconstruction have been reported in 67% to 92% of ankles. Proper patient selection is critical, because ankle malunions can be complicated, with coexisting fibular, syndesmotic, medial, and posterior malleolar malalignment, along with degenerative joint disease. Understanding the indications and surgical technique for revising fibular malunions may obviate a future salvage procedure. Dr. Chu is Assistant Professor, Pediatric Orthopaedic Surgery, Department of Orthopaedic Surgery, NU Hospital for Joint Diseases, New ork, N. Dr. Weiner is Chief of Trauma, Lenox Hill Hospital, New ork, N. Neither of the following authors or a member of their immediate families has received anything of value from or owns stock in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Chu and Dr. Weiner. Reprint requests: Dr. Chu, Department of Orthopaedic Surgery, NU Hospital for Joint Diseases, 301 East 17th Street, New ork, N J Am Acad Orthop Surg 2009;17: Copyright 2009 by the American Academy of Orthopaedic Surgeons. Posttraumatic osteoarthritis is the leading cause of ankle arthritis, a debilitating condition that usually occurs in a younger patient population. Rotational ankle fractures, most of which involve a significant lateral malleolar injury, are the primary type of injury leading to posttraumatic ankle arthritis. 1 It is important to understand the mechanism by which distal fibula malunions lead to tibiotalar instability and the appropriate methods used to diagnose and treat the condition. Distal fibular corrective osteotomies with or without syndesmotic fixation have a distinct effect in preventing the progression of established ankle arthritis. Increased use of fibular reconstruction in carefully selected cases might decrease the need for joint-sacrificing procedures such as arthrodesis or arthroplasty. Effect of Fibular Fracture on Ankle Stability The ankle joint is composed of the articulation between the talus, distal tibia, and distal fibula. During normal motion, the talus externally rotates 4.2 with dorsiflexion and internally rotates 1.4 with plantar flexion. 2 Because of this motion and the trapezoidal shape of the talar body, the geometry of the ankle mortise changes during dorsiflexion and plantar flexion. The distal fibula accommodates for the increased dimensions by lateral translation of 1 to 2 mm and by external rotation during ankle dorsiflexion. An unstable ankle joint is defined by abnormal talar motion under physiologic conditions, leading to dynamic tibiotalar incongruity. 3 Axial loading increases ankle stability. 220 Journal of the American Academy of Orthopaedic Surgeons

2 Alice Chu, MD, and Lon Weiner, MD A recent study quantified the contribution of ankle congruence on stabilization during weight-bearing activities. 4 The deltoid ligament is the main stabilizer of talar motion, but when it is disrupted (as in the case of unstable ankle fractures), the distal fibula provides a secondary stabilizing function. 5,6 In studies on the effects of distal fibular displacement versus deltoid ligament sectioning on ankle motion, disruption of the deep deltoid ligament caused abnormal talar motion while fibular osteotomy and displacement did not. 2,7 However, when the deep deltoid ligament was cut first, fixation of the distal fibula by anatomic reduction and internal fixation partially restored talar kinematics. 7 Anatomic reduction of the distal fibula leads to restoration of the tibiotalar articulation, thus increasing stability. In cadaveric models of unstable ankle fractures, small fibular displacements lead to significantly increased tibiotalar contact pressures. 8 Additionally, the distal fibula, through its articulation at the tibiofibular joint, directly affects alignment of the ankle syndesmosis. Leeds and Ehrlich 9 showed a significant correlation between reduction of the lateral malleolus and the syndesmosis, as well as between initial syndesmotic reduction and late stability of the syndesmotic at an average of 2 to 7 years follow-up. Unstable ankle fractures may involve injury to the medial ligaments. In certain types of fractures, deltoid ligament stability is not restored with medial malleolar fixation. 10 When the deltoid ligament is ruptured, not repairable, or chronically attenuated, reduction of the distal fibula serves several functions. One benefit is restoration of the medial talomalleolar space, which allows the deltoid ligament to heal at its resting length and tension. Additionally, anatomic reduction of the distal fibula provides stability by restoring the articular configuration of the tibiotalar joint. Finally, in the case of associated syndesmotic rupture, restoration of tibiofibular geometry secondarily provides reduction of the syndesmosis. The goal of surgical intervention in an unstable ankle fracture malunion is to repair the fixable elements, such as bone malreductions, to offer the best chance of obtaining talar stability. Diagnosis The assessment of patients with lateral malleolar malunions is challenging because of the lapsed time from injury to evaluation and potential surgical correction as well as the complexity of analyzing a healed injury. The assessment is complicated by the extensive list of potential coexistent malunions or malreductions of other parts of the ankle. Patients with a history of rotational fracture of the ankle may present years after the initial injury with insidious, progressive pain, often with swelling after activity. 11 The pain may be intermittent or vague, occurring from transfer of stress to other parts of the foot and ankle. Deformity of the foot and ankle should be assessed, and concomitant disease processes such as posterior tibial tendon dysfunction or missed Lisfranc fracture should be ruled out. A standard series of radiographs is the first step in assessing symptomatic ankle fracture malunion. Cortical irregularities or fracture callus may provide clues about the original injury fracture pattern. After the presence of a nonunion is ruled out, the ankle mortise should be inspected for signs of instability of the talus. Subtle findings should be noted and followed at regular intervals because small discrepancies on radiographs can progress over time. Significant markers for potential instability include asymmetry of the medial and lateral clear spaces on the mortise view, talar tilt >2 mm, and any amount of talar subluxation. Other radiographic findings include valgus talar alignment, a lateral position of the talus, and eccentric joint space narrowing. Instability secondary to widening of the syndesmosis will demonstrate an increased tibiofibular clear space and decreased tibiofibular overlap. Distal fibular malunion is associated with talar instability with or without syndesmotic widening. Shortening of the fibula can be correlated with the bimalleolar and talocrural angles. These are two similar radiographic markers of fibular length that require comparison with the contralateral, uninjured ankle to determine significance (Figure 1). The angles are formed by the bisection of the mechanical axis with the intermalleolar line. The mechanical axis is estimated either by the line perpendicular to the tibial plafond (talocrural angle) or the line parallel to the distal fibular shaft (bimalleolar angle). The talocrural angle averages 78.5, with a normal range of from 75 to Abnormal fibular shortening is reflected by an approximate linear relationship of 1 angle difference to 1 mm of shortening. Additionally, Weber and Simpson 13 formulated observations into three criteria for normal distal fibular length as seen on the radiographic mortise view: (1) equal joint space, (2) intact Shenton line of the ankle, and (3) an unbroken curve between the lateral talus and the peroneal groove of the fibula (Figure 2). In a typical bimalleolar fracture, the distal fibula externally rotates relative to the talus. Thus, the direction of displacement of the distal fragment tends to be proximal, posterior, and lateral. 14 Some surgeons recommend obtaining a lateral ra- April 2009, Vol 17, No 4 221

3 Distal Fibula Malunions Figure 1 Illustrations demonstrating measurements of fibular length based on mortise radiographic views. A, The talocrural angle uses the line perpendicular to the tibial plafond as the vertical line. B, The bimalleolar angle uses the intramedullary canal of the distal fibula as the vertical line. The bisector is the intermalleolar line. Normal values range from 75 to 86. (Adapted with permission from Rolfe B, Nordt W, Sallis JG, Distefano M: Assessing fibular length using bimalleolar angle measurements. Foot Ankle 1989;10: ) Figure 2 A, Three criteria for normal distal fibula length as seen on the mortise view. 1, Equal joint space. 2, Intact Shenton line of the ankle. The contour of the dense subchondral bone of the tibia can be followed over the syndesmotic space to the fibula, where a small spike is seen. This spike points directly to the level of the tibial subchondral bone. 3, Unbroken curve between the lateral talus and the peroneal groove of the fibula. B, Shortened fibula showing disruption of all three criteria. (Adapted with permission from Weber BG, Simpson LA: Corrective lengthening osteotomy of the fibula. Clin Orthop Relat Res 1985;199:61-67.) diograph of the ankle because it often provides a better view of the distal fibula malunion. 9,11 Michelson et al 15 measured the average displacement in distal fibula fractures and found posterior displacement to be the largest at an average of 3.8 mm, followed by lateral at 3 mm and proximal at 2.9 mm. The lateral radiograph thus shows the direction of largest absolute displacement in most distal fibula fractures. Subtle syndesmotic widening is notoriously difficult to measure by means of standard radiographic views. 16,17 Lui et al 18 compared stress views with ankle arthroscopy and considered arthroscopy to be the definitive means for diagnosis. Xenos et al 19 compared mortise and lateral stress views in cadaveric models with anterior syndesmotic tears and found that the lateral view had a higher correlation with diastasis. In acute fractures, external rotation stress views can be used to distract a syndesmotic injury, but no studies have looked specifically at the utility of stress radiographic views in chronic syndesmotic ruptures. Computed tomography (CT) is a useful adjunctive diagnostic tool. In particular, CT imaging can be used to rule out an associated syndesmotic widening when the radiographic markers are equivocal. 20,21 No one method has been clinically validated, although several have been described. These include comparing bilateral axial CT sequences to assess congruity of the tibiofibular joint, and using a formula for calculating the volume of the tibiofibular space. 17,22 One study determined syndesmotic widening by a measurement of >2 mm of difference between the anterior and posterior distances from the fibula to the incisura of the tibia at a preset axial level. 23 Using those criteria, the investigators found a 52% prevalence of malreduction following open reduc- 222 Journal of the American Academy of Orthopaedic Surgeons

4 Alice Chu, MD, and Lon Weiner, MD tion and internal fixation of unstable ankle fractures, compared with only 24% when using standard radiographic measurements. However, the clinical implications of the amount of syndesmotic malreduction seen in patients were not addressed in that study and currently are not well established. When the presence of chronic syndesmotic injury is equivocal on a CT scan, magnetic resonance imaging (MRI) may be used. 24 Supination external rotation or low fibula fractures are associated with tibiofibular injury in up to 39% of cases In contrast, pronation external rotation or high fibula fractures are generally assumed to involve a syndesmotic injury unless the mechanism of injury dictates otherwise. 29,30 The diagnostic studies used in the workup for ankle malunions yield three main findings or objectives: reduction of the talus in the mortise, reduction and stability of the syndesmosis, and restoration of the length and alignment of the fibula. Management The management of ankle malunions is controversial. Decision making should be influenced primarily by the condition of the joint cartilage but may also be affected by factors such as age, time from injury, activity level, and comorbidities. Not all distal fibular malunions are symptomatic. Leeds and Ehrlich 9 followed 17 bimalleolar fractures with fair or poor lateral malleolar reduction and found mixed results even with poor syndesmotic reduction. Ten patients had good objective and subjective results at the time of follow-up, and two of those patients had good results in spite of fair or poor reduction of the syndesmosis. Although one cadaveric study showed changes in the tibiotalar contact area with Table 1 Classification of Osteoarthritic Changes in the Ankle Grade fibular malreductions as small as 2 mm, 8 a larger clinical study is needed to determine the degree of fibular malreduction that is significant. The natural history of symptomatic ankle instability secondary to malunion is variable, with onset of symptoms delayed from months to >10 years after initial injury. 11 Nonsurgical treatment such as nonsteroidal anti-inflammatory drugs, steroid injections, activity modification, and orthoses may be acceptable for patients with manageable pain levels who have limited weight-bearing demands. However, ankle arthritis following rotational ankle fracture is typically found in a younger, active patient population, with one study reporting an average age of 50.8 years. 1 Surgical management for ankle malunions should be considered after selected and detailed preoperative discussions with the patient about her or his goals and willingness to accept additional surgery. Although there is generally clinical improvement after ankle reconstruction surgery, the amount will vary by the individual and the presenting deformity. Surgery may succeed in delaying joint degeneration secondary to instability, but the degree of established arthritis will determine the final results. The patient should be cautioned that the benefits of reconstruction surgery (ie, maintaining native bone stock and some degree of Characteristics 0 Normal joint or subchondral sclerosis I Osteophytes without joint space narrowing II Joint space narrowing with or without osteophytes III Subtotal or total disappearance or deformation of the joint space Reproduced with permission from van Dijk CN, Tol JL, Verheyen CC: A prospective study of prognostic factors concerning the outcome of arthroscopic surgery for anterior ankle impingement. Am J Sports Med 1997;25: motion) might come at the expense of persistent arthritic pain and the need for further surgical procedures. To improve prediction of postoperative function, an accurate evaluation of the preexisting level of ankle arthritis is important when making a surgical recommendation. Several radiographic arthritis classification systems have been described. van Dijk et al 31 proposed a classification for ankle arthritis that was originally used to separate treatable ankle impingement from end-stage arthritic cases (Table 1). Giannini et al 32 proposed a treatment algorithm of posttraumatic ankle arthritis using the van Dijk classification. In that algorithm, the authors recommended joint reconstruction (ie, lateral malleolar osteotomies with or without other procedures) for grade II arthritis with intra-articular malalignment, but advocated ankle allograft, arthroplasty, or tibiotalar fusion for grade III ankle joints. Unfortunately, the standard osteoarthritis classifications may not be applicable to the subluxated, unstable ankle. Evaluation of the joint space in a malunited position can be misleading. In some cases, reduction of the tibiotalar joint will seemingly demonstrate improvement of the joint space. Assessment of early arthritis is difficult, but the presence of arthritis may be inferred with certain MRI sequences or contrast-agent techniques such as fat-suppressed April 2009, Vol 17, No 4 223

5 Distal Fibula Malunions T1-weighted spoiled gradient-echo, fat-suppressed T2-weighted fast spin-echo, or delayed gadoliniumenhanced MRI scans of cartilage. 33 Clinical findings are also important determinants of the need and feasibility of reconstruction. The presence of anterior or posterior ankle impingement as a separate entity should be established preoperatively. Patients with relatively good ankle range of motion (>5 dorsiflexion and >15 plantar flexion) tend to have better outcomes after reconstruction, whereas those with limited motion benefit more from total ankle arthroplasty or arthrodesis. Distal Fibula Reconstruction Technical Considerations Once the decision has been made to revise the distal fibula, several technical considerations arise. Surgeons have presented varying types and locations of fibula osteotomy, with or without syndesmotic fixation or use of autologous bone graft. Most series used the same technique in all cases, regardless of the type of fibula malunion. 11,13,34-36 The largest published study on lateral malleolar reconstructions involved a series of 26 patients. 11 The surgical protocol called for a transverse osteotomy at the level of the fracture site, with autologous tibial graft if the osteotomy gap exceeded 3 mm. The authors emphasized complete visualization and anatomic reduction of the tibiofibular joint, with use of a syndesmotic screw for fixation. Syndesmotic reduction and fixation was performed on all patients in the study. Weber and Simpson 13 described a series of 23 patients treated with lengthening osteotomy of the distal fibula, none of whom received syndesmotic fixation (Figure 3). Intraoperatively, the surgeons visualized the tibiofibular joint to ascertain reduction and performed a syndesmotic reduction without internal fixation. Although the authors described clearing the tibiofibular joint to obtain complete exposure for reduction, the extent to which the joint was exposed for the reduction and the precise location of the fibula osteotomy (ie, distance from the joint) is unspecified. In this series, most cases showed improvement with fibular lengthening and tibiofibular reduction without syndesmotic fixation. More recent studies have discussed ways of establishing fibular length without the need for structural, autologous bone graft. Chao et al 35 described a long oblique osteotomy in the sagittal plane at the level of the prior fracture. After mobilizing the tibiofibular ligaments, the surgeons were able to slide the distal fragment 4 to 5 mm without difficulty. Weber et al 37 compared two groups of fibular osteotomies using a standard transverse cut versus a sliding Z-osteotomy in the coronal plane. In a series of six patients, no difference was noted in the postoperative outcome with regard to the type of osteotomy performed. Intraoperative Distraction Stable distraction is important during a fibula lengthening procedure because it allows for easier placement of internal fixation. Several methods have been described, including fixing the reduced talus to the medial aspect of the tibia with a Steinmann pin or using an AO small distractor or pin clamp over Kirschner wires. 11,36,38 Controlled rotation can be obtained by fixing the plate posteriorly on the distal fragment and rotating the plate so that it lies flush on the lateral aspect of the proximal segment. 13 A jointspanning external fixator may be used intraoperatively to hold the fibula reduction (Figure 4). One case report described a combination of unilateral fixator and Ilizarov frame to lengthen the distal fibula in a patient with 1 cm of shortening secondary to a unicameral bone cyst. A tibial anchor point was employed to ensure distal rather than proximal lengthening. 39 Authors Preferred Technique Rotational ankle fracture malunions are difficult to categorize because of the unique aspects of each case. Types of malunion include medial or posterior malleolar injury, associated nonunions, and missed talar defects. For lateralsided rotational ankle malunions, two critical preoperative assessments are necessary: whether there is a concomitant syndesmotic injury, and the direction of correction required (ie, shortening, malrotation, lateral displacement, or a combination of all three). Because the literature shows that distal fibular malrotation may be a significant factor in ankle malunions, our choice of two osteotomy types allows for incorporation of rotational correction. 15,23 The stability of the syndesmosis determines the level of osteotomy. For fibula fracture patterns below the level of the syndesmosis that have no associated instability and require small changes (ie, 2 to 4 mm) in fragment mobility, we use a low, oblique osteotomy, which allows for manipulation without iatrogenic syndesmotic destabilization (Figure 5). Because the osteotomy takes place below the syndesmosis, the distal piece can be mobilized without dissection of the tibiofibular joint. This is a relatively short osteotomy that traverses from proximal-lateral to distal-medial. It makes use of a medial spike and the residual lateral displacement of the malunited fibula to recreate length in the distal fibulartalar joint, without producing a significant cortical gap. Additionally, the distal fragment can be rotated or 224 Journal of the American Academy of Orthopaedic Surgeons

6 Alice Chu, MD, and Lon Weiner, MD Figure 3 The Weber-Simpson surgical technique of fibular lengthening. A, Ankle fracture malunion with isolated fibular malreduction. B, After a transverse, suprasyndesmotic osteotomy is performed, a fixation plate is applied distally. (Upper inset: the plate can be placed in a posterior position to allow for internal rotation of the distal fragment; lower inset: the lateral surface of the fibula at that location may need to be recessed to allow the plate to sit directly on bone.) C, A small AO distractor is positioned proximally for stable, intraoperative distraction. D, Proximal screws are placed once the fibula is properly positioned. Tibial autograft or compression through the AO device is optional. E, Restoration of the tibiotalar mortise. Additionally, replacement of one of the distal screws with a syndesmotic screw is recommended. (Adapted with permission from Weber BG, Simpson LA: Corrective lengthening osteotomy of the fibula. Clin Orthop Relat Res 1985;199:61-67.) medially translated as needed. For malunions with syndesmotic injury, including high fibula fractures (eg, pronation external rotation type 4) or low fibula fractures with documented tibiofibular instability, we use a transverse osteotomy above the level of the syndesmosis as described by ablon and Leach 11 (Figure 6). Through an anterolateral window, the tibiofibular joint must be directly examined to ensure an anatomic reduction. The distal fibula can be mobilized and manipulated in the axial, coronal, and sagittal planes. Because the osteotomy lacks bony contact after distraction, structural bone graft is required when the distance between bone ends is large (>3 mm) to decrease the risk of nonunion. One or two 3.5-mm syndesmotic screws, crossing four cortices, are placed through the lateral plate at the conclusion of the procedure. Three different methods are used to maintain fibula length during placement of internal fixation. We April 2009, Vol 17, No 4 225

7 Distal Fibula Malunions Figure 4 Mortise view radiograph demonstrating an external fixator applied to distract the ends of the fibular osteotomy before hardware fixation. Figure 5 generally use a smooth lamina spreader to distract the fibular osteotomy while the lateral plate, a 3.5-mm dynamic compression plate, is transfixed. If the lamina spreader provides insufficient temporary stability, we apply a small AO distractor proximal to the plate. For patients requiring concurrent ankle arthroscopy and débridement, we use a joint-spanning external fixator for distraction throughout the case. In most fibular malunions, a medial-sided procedure, such as incision and débridement of the medial gutter or arthroscopy, is indicated to address intra-articular fibrosis. 40 In long-standing malunions, scar tissue will be a deterrent to achieving anatomic reduction of the ankle mortise. The most important intraoperative radiographic criteria to assess quality of the fibular reduction are those that determine whether the talus is congruently seated and are, specifically, lateral talar subluxation, medial joint space widening, and talar tilt. Fibular length measurements (eg, talocrural angle, bimalleolar angle) compared with those of the contralateral side can be helpful as well. Plain radiographs are useful in many cases; fluoroscopy may be misleading when used to analyze subtle talar shifts. 41 Postoperative Treatment The goal of the immediate postoperative course is to ensure healing of the fibular osteotomy and syndesmotic ligaments. Non weight bearing is maintained for 6 to 10 weeks, depending on patient-related factors such as age, comorbidities, and smoking. Surgery-related factors such as the use of interpositional graft, the choice of allograft over autograft, and gapping at the osteotomy site may negatively affect the rate of healing and help determine the period of non weight bearing. Osteotomies with slow or tenuous healing should be followed closely, maintained on a strict non weightbearing protocol, and evaluated with A, Mortise view radiograph of a supination external rotation fibular malunion showing medial talomalleolar widening as well as valgus tilt of the talus. This patient presented with residual foot and ankle pain approximately 1 year after initial surgical treatment of the fracture. B, Illustration demonstrating preoperative templating with the proposed short, oblique osteotomy performed below the level of the syndesmosis. C, The talocrural angle (TC) decreased from 82 to 79, reflecting an increase in length of approximately 3 mm. D, Mortise ankle radiograph taken 18 months postoperatively. The mortise has been maintained, and there is little radiographic evidence of advancing arthritis. The patient described her clinical improvement as ninety percent. 226 Journal of the American Academy of Orthopaedic Surgeons

8 Alice Chu, MD, and Lon Weiner, MD CT scans to assess the progress of healing. Weight bearing can be commenced without removal of syndesmotic screws. We believe that the need for screw removal is not absolute and that the screws should remain for a minimum of 6 months. The decision to remove the screws, such as for loosening or pain relief or when a future syndesmotic fusion is probable, is made on an individual basis. If the screws have broken during the course of weight bearing, they can be retrieved from the medial and lateral aspects. Retrieval is easier when the screws traverse four cortices. Follow-up visits are scheduled at 2-month intervals for the first year, and annually thereafter. A standard series of anteroposterior, lateral, and mortise radiographs is taken at all office visits and examined primarily for signs of talar instability. Figure 6 A, Mortise view radiograph of a pronation external rotation distal fibula nonunion with significant shortening and lateral displacement as well as concomitant syndesmotic instability. B, Postoperative anteroposterior radiograph after exploration of the prior fracture site, bone grafting, and reduction and fixation of the distal fibula with a single syndesmotic screw. Results Most published series of ankle malunions are retrospective and comprise small patient numbers (Table 2). In earlier studies, analysis of the data focused on correlating outcome with such variables as age or sex of the patient, type of fibula fracture, time from injury, quality of reduction achieved, and preoperative state of the cartilage. Weber and Simpson 13 were the first to emphasize careful selection of patients when they noted that all six fair-topoor results in their series had preoperative radiographs showing moderate to severe degenerative arthritis. As with some other surgical procedures, the objective results did not always correlate with subjective data. In one series, three of four patients had good results at 1- to 5-year follow-up despite poor reduction and the presence of mild and moderate osteoarthritis. 34 Another report described a fair result in a patient with persistent tibiofibular diastasis who was nevertheless able to run and had no evidence of progressive narrowing of the joint space. 35 When radiographic progression of arthritis is used as the determinant, the success rate in fibular lengthening procedures is reported to be 50% to 100% at follow-up of 3 months to 22 years. 11,35,37 The most recent study stated that all 12 patients in the series had no radiographic progression of arthritis at an average of 34 months follow-up and that a longerterm study was forthcoming. 35 In the same study, the sagittal range of motion improved only slightly, from 28 to 35. Good and excellent clinical outcomes have varied from 67% to 92% at short to intermediate followup Although these series are small, with an average of 14 ankles, the results are encouraging. Salvage Procedures In the event of persistent pain and a severely arthritic joint, salvage procedures should be considered. Currently, tibiotalar arthrodesis is preferred because it is a procedure with consistent pain control, reproducibility, and durability. 44 It has high satisfaction rates, with most patients reporting that they would have the surgery again. However, arthrodesis has several disadvantages. Tibiotalar motion is sacrificed in a relatively young patient population, leading to development of subtalar arthritis in 60% to 100% of patients reviewed in long-term studies. 45,46 Patients receiving pantalar fusion have significant disability because they have no motion in the ankle and hindfoot, and they have few revision options. 47 Total ankle arthroplasty is another surgical option for patients with end- April 2009, Vol 17, No 4 227

9 Distal Fibula Malunions Table 2 Published Series Reporting Outcomes for Surgical Treatment of Distal Fibula Malunion Study* No. of Revisions Average Follow-up Time (Range) Average Time From Injury (Range) Good to Excellent Results (%) Radiographic Analysis at Follow-up Tibiofibular Joint Reduction Syndesmotic Fixation Fibular Revision Only Offierski et al yr (1-7 yr) 10 mo (3-36 mo) 8 (73) 7 anatomic reductions, 4 with residual talar tilt Weber and Simpson yr (5-16 yr) 3-48 mo 17 (74) 6 with progression of arthritis ablon and 26 7 yr ( yr) 6 yr (1-22 yr) 23 (88) No progression of Leach 11 arthritis in 20 ankles Ward et al yr (2-3 yr) 12 mo (1-48 mo) 5 (83) 5 with good reduction Weber et al yr ( yr) Chao et al mo (27-48 mo) 36 mo (5-60 mo) 4 (67) 2 without progression, 1 very slight at 4 yr postoperatively, 3 slight progression 18 mo (6-48 mo) 11 (92) 1 with diastasis but improved, 12/12 showed no radiographic progression of arthritis Fibular Osteotomy + Other Procedures Marti et al yr ( yr) 22 mo 22 (71) Almost no progression of arthritis Roberts et al mo (12-54 mo) 3 mo (1-6 mo) All ambulating well Giannini et al yr NR ~39 (93) Slight radiographic progression of arthritis * All studies are level IV evidence Open reduction of tibiofibular joint performed routinely N = no, NR = not reported, S = sometimes, = yes NR NR S N NR N S N S S stage ankle arthritis. 48 This procedure preserves tibiotalar motion, which helps to spare development of arthritis in the subtalar joints. However, problems with total ankle arthroplasty include loosening and subsidence, especially of the talar side. 49 With the advent of new advances in ankle arthroplasty prosthetic design and surgical technique, future studies may show improved results. 50 Summary Distal fibula malunions are problematic because they disrupt the congruency of the ankle mortise, which is of significance when the talus is dynamically unstable, and because they cause malreduction of the tibiofibular joint in conjunction with syndesmotic rupture. Diagnosing fibula malunion requires systematic review of plain radiographs or CT scans to ascertain the geometry of the malunion and to rule out other injuries. The management of these cases is difficult and controversial because there are no controlled, long-term studies showing stable, pain-free ankle joints and absence of secondary procedures, such as ankle arthrodesis. References Evidence-based Medicine: There is one level I prospective study reporting outcome of ankle arthroscopy (reference 31) but none pertaining to fibula malunions. The other cited references are level III cohort case studies or level IV case reports on therapeutic benefits, as well as diagnostic studies. Citation numbers printed in bold type indicate references published in the past 5 years. 1. Saltzman CL, Salamon ML, Blanchard M, et al: Epidemiology of ankle arthritis: 228 Journal of the American Academy of Orthopaedic Surgeons

10 Alice Chu, MD, and Lon Weiner, MD Report of a consecutive series of 639 patients from a tertiary orthopaedic center. Iowa Orthop J 2005;25: Sasse M, Nigg BM, Stefanyshyn DJ: Tibiotalar motion: Effect of fibular displacement and deltoid ligament transaction. In vitro study. Foot Ankle Int 1999;20: Michelson JD: Ankle fractures resulting from rotational injuries. J Am Acad Orthop Surg 2003;11: Tochigi, Rudert MJ, Saltzman CL, Amendola A, Brown TD: Contribution of articular surface geometry to ankle stabilization. J Bone Joint Surg Am 2006;88: Pankovich AM, Shivaram MS: Anatomical basis of variability in injuries of the medial malleolus and the deltoid ligament: I. Anatomical studies. Acta Orthop Scand 1979;50: Leardini A, O Connor JJ, Catani F, Giannini S: The role of the passive structures in the mobility and stability of the human ankle joint: A literature review. Foot Ankle Int 2000;21: Michelsen JD, Ahn UM, Helgemo SL: Motion of the ankle in a simulated supination-external rotation fracture model. J Bone Joint Surg Am 1996;78: Thordarson DB, Motamed S, Hedman T, Ebramzadeh E, Bakshian S: The effect of fibular malreduction on contact pressures in an ankle fracture malunion model. J Bone Joint Surg Am 1997;79: Leeds HC, Ehrlich MG: Instability of the distal tibiofibular syndesmosis after bimalleolar and trimalleolar ankle fractures. J Bone Joint Surg Am 1984;66: Tornetta P III: Competence of the deltoid ligament in bimalleolar ankle fractures after medial malleolar fixation. J Bone Joint Surg Am 2000;82: ablon IG, Leach RE: Reconstruction of malunited fractures of the lateral malleolus. J Bone Joint Surg Am 1989; 71: Rolfe B, Nordt W, Sallis JG, Distefano M: Assessing fibular length using bimalleolar angular measurements. Foot Ankle 1989;10: Weber BG, Simpson LA: Corrective lengthening osteotomy of the fibula. 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