Current Concepts Review: Peroneal Tendon Subluxation and Dislocation

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1 FOOT &ANKLE INTERNATIONAL Copyright 2007 by the American Orthopaedic Foot & Ankle Society, Inc. DOI: /FAI Current Concepts Review: Peroneal Tendon Subluxation and Dislocation Brent K. Ogawa, M.D.; David B. Thordarson, M.D. Los Angeles, California INTRODUCTION Peroneal tendon subluxation or dislocation often is misdiagnosed as an ankle sprain. 1,15,18,33 Chronic dislocation can cause chronic pain or a sense of instability. Although both conservative and operative methods have been advocated for treatment of acute injuries, currently surgical management is generally recommended for both acute and chronic injuries. Numerous operative techniques have been described, including rerouting procedures, soft-tissue repair and reconstruction, and bony procedures. Results usually are excellent after correct diagnosis and appropriate treatment. 4 ANATOMY, ETIOLOGY, AND MECHANISM OF INJURY The peroneus longus and brevis muscles form the lateral compartment of the leg. From their origins on the proximal fibula, they run distally, becoming tendinous proximal to the ankle joint. The peroneus brevis lies medial and anterior to, and is partially covered by, the peroneus longus tendon. The posterolateral aspect of the fibula has a shallow sulcus that tapers distally. In an anatomic study of 178 cadavers, Edwards 9 reported that 82% had a concave sulcus, 7% had a convex sulcus, and 11% had a flat sulcus. The peroneal groove was 5 to 10 mm wide and up to 3 mm deep. In contrast, Eckert and Davis 8 found in dissections of 25 cadavers that the posterior surface of the fibula was flat and, when a shallow groove was present, it was highly variable in depth. The fibro-osseous tunnel around the peroneal tendons is composed of four sides. (Figure 1). The anterior wall is formed by the fibula and the posterior wall by the deep investing fascia of the leg and the calcaneofibular ligaments. The posterior talofibular and calcaneofibular ligaments medially and the superior peroneal retinaculum laterally are the final components of the tunnel encompassing the peroneal tendons. The superior peroneal retinaculum (SPR) is a primary restraint to instability of the peroneal tendons at the fibular malleolus. 8,9 The SPR extends approximately 3.5 cm proximal from the tip of the lateral malleolus to attach posterolaterally onto the calcaneus and the deep investing fascia adjacent to the Achilles tendon. The inferior component of the SPR forms two fibro-osseous tunnels that hold the peroneal tendons onto the lateral aspect of the calcaneus. Anatomical variants can cause peroneal tendon instability. An anomalous extension of the peroneus brevis muscle into the fibular groove can cause stretching of the SPR, longitudinal splitting of the peroneus brevis tendon, and peroneal tenosynovitis. 36 A bifid peroneus brevis musculotendinous unit also has been reported as a cause of subluxation. 12 In a cadaver study of 30 specimens, the SPR was variable in width, thickness, and insertional patterns. 6 At least one insertional band running parallel and inserting lateral to the calcaneofibular ligament also was noted. Occasionally, when the calcaneofibular ligament sustains an inversion injury, the SPR is stretched or torn resulting in instability. 6 Corresponding Author: David B. Thordarson, M.D. Department of Orthopaedic Surgery Keck School of Medicine University of Southern California 1200 N. State Street, GNH 3900 Los Angeles, CA thordars@usc.edu For information on prices and availability of reprints, call X David B. Thordarson, M.D.

2 Foot & Ankle International/Vol. 28, No. 9/September 2007 PERONEAL TENDON SUBLUXATION 1035 Table 1: Level of evidence and grades of recommendation Level of Evidence Level I: high quality prospective randomized clinical trial Level II: prospective comparative study Level III: retrospective case control study Level IV: case series Level V: expert opinion Grades of Recommendation (given to various treatment options based on Level of Evidence supporting that treatment) Grade A treatment options are supported by strong evidence (consistent with Level I or II studies) Grade B treatment options are supported by fair evidence (consistent with Level III or IV studies) Grade C treatment options are supported by either conflicting or poor quality evidence (Level IV studies) Grade I when insufficient evidence exists to make a recommendation that most procedures to correct peroneal tendon instability are unsuccessful unless ankle instability also is corrected. Geppert et al. 11 observed that, with increasing degrees of lateral ankle instability, the SPR becomes more attenuated, decreasing its effectiveness as a secondary restraint to ankle inversion stress. Congenital deformities of the leg muscles, bones, or soft tissues also can be a cause of peroneal tendon dislocation. Congenital vertical talus, talipes planovalgus, 23 congenital absence of the peroneal retinaculum, 1 hyperelasticity, 12 anomalous peroneus brevis, 12,36 and bilateral congenital subluxation secondary to insufficient fibular groove depth 31 have all been described as causing tendon dislocation. Acquired deformities such as osteochondromas causing distortion of the groove also have been reported. 23 Most acute peroneal tendon subluxations or dislocations occur during athletic activities such as skiing, iceskating, soccer, basketball, rugby, dancing, running, and football. 1,7,15,16,18,19 The most consistently described mechanism of peroneal tendon injury is dorsiflexion of the foot with powerful contraction of the peroneals, which causes failure of the SPR leading to subluxation or dislocation of the tendons. During dorsiflexion, the peroneal tendons tighten against the posterior fibula, while eversion causes the tendons to deviate laterally. The calcaneofibular ligament tightens and decreases the width of the fibro-osseous tunnel and pushes the tendons against the SPR (Figure 2). The fibrocartilaginous ridge at the anterior edge of the fibula is only loosely connected with the periosteum and does not provide a strong attachment for the SPR, which blends with the periosteum of the lateral aspect of the malleolus. Thus, as the peroneal tendons are dislocated from the fibula, the ridge usually remains on the fibula while the SPR strips the periosteum from the fibula. Tendon dislocation also can occur with an inversion injury with the foot in plantarflexion because this also can stretch or avulse the SPR. Eckert and Davis 8 described the mechanism of injury in 73 acute ruptures of the SPR as forced dorsiflexion that occurred when a ski tip became embedded in the snow. CLASSIFICATION Fig. 1: Anatomy of the peroneal tendon complex. A, Peroneus longus. B, Peroneus brevis. C, Fibrous lip. D, Superior peroneal retinaculum. Associated ligamentous instability or varus malalignment can contribute to peroneal tendon instability. Lateral ankle instability has been reported to be associated with peroneal tendon instability. 11,13,17,20,29,30,37 Sobel et al. 37 suggested Shawen and Anderson 34 divided peroneal tendon injuries into two zones: zone I injuries involve the fibular groove and most often affect the peroneus brevis tendon, while zone II injuries are located in the cuboid tunnel and primarily involve the peroneus longus tendon. As the peroneus brevis tendon subluxes in the fibular groove, it is forced against the sharp bony ridge causing a longitudinal split in the tendon from a 45-degree course change and the overlying peroneus longus tendon. Eckert and Davis 8 described three grades of anatomic injury (Figure 3): grade 1, the retinaculum (SPR) with the periosteum is stripped off the lateral malleolus (51%); grade 2, the distal 1 to 2 cm of the dense fibrous ridge of the fibular

3 1036 OGAWA AND THORDARSON Foot & Ankle International/Vol. 28, No. 9/September 2007 the subluxation. Anterior drawer and talar tilt maneuvers should be done to evaluate lateral ankle instability. Safran et al. 32 described a provocative test in which, with the patient prone and the knee flexed, the ankle is actively dorsiflexed and plantarflexed with resisted eversion to visibly assess the dynamic stability of the tendons. Gait and hindfoot alignment also should be evaluated. Fig. 2: Peroneal tendon dislocation with tear of superior peroneal retinaculum.. Fig. 3: Eckert and Davis classification. malleolus are elevated along with the retinaculum, making the tendons very unstable when reduced (33%); and grade 3, the SPR avulses a thin fragment of bone anteriorly along the fibrous ridge (16%). Oden 26 modified this classification by defining grade 2 as a tear of the retinaculum from its fibular attachment (not periosteal elevation) and adding avulsion from the posterior insertion site as grade 4. Diagnostic Studies Radiographs are useful to evaluate coexisting ankle pathology and may identify fractures or osteochondral lesions. In grade 3 subluxations, a small avulsed piece of the lateral malleolus (fleck sign) may be visible and may be as large as 1 to 2 mm thick and 2 cm long; however, while pathognomonic, this avulsed fragment is evident on fewer than half of radiographs of grade 3 subluxations. 26 Advances in diagnostic capabilities have made other imaging modalities helpful in evaluating peroneal tendon injuries. CT scanning can assess the bony anatomy of the fibular groove, which cannot be assessed on plain radiographs. 40 Magnetic resonance imaging (MRI) can show tendon malposition, tendinitis, partial tendon tears, and peroneal tendon ruptures, as well as the SPR and muscle belly of the peroneus brevis 5 (Figure 4). CT scanning and MRI are less reliable for identifying transient or episodic subluxated or dislocated tendons. Shellock et al. 35 used kinematic MRI of the ankle moving from dorsiflexion to plantarflexion to assess for subluxation. In their small study, they concluded that because the pathology is position-dependent, static images are less helpful than dynamic images in assessing the abnormality. Ultrasound also has been reported to be an effective technique for dynamically evaluating peroneal tendon subluxation, as well as associated tears of the peroneal tendons. 25 CLINICAL PRESENTATION AND DIAGNOSIS The diagnosis of peroneal tendon subluxation or dislocation is made primarily from the patient s history and physical examination. The physician must have a high index of suspicion because these complaints can be misdiagnosed as an ankle sprain. 1,4,15,18,33 Patients may report hearing a pop or snap at the time of injury or with walking after the injury. They may report a sensation of instability when walking on uneven surfaces. With acute injuries posterolateral ankle ecchymosis, swelling, and tenderness may be present, and activating the peroneals will produce pain. Pain is localized to the posterior aspect of the fibula rather than more anteriorly as occurs with an ankle sprain. Patients with chronic injuries may report a snapping sensation along the tip of the fibula or a feeling of ankle instability. They usually complain of retromalleolar pain. Dorsiflexion and eversion against resistance can reproduce Fig. 4: Transverse T2-weighted MRI demonstrating disrupted superior peroneal retinaculum

4 Foot & Ankle International/Vol. 28, No. 9/September 2007 PERONEAL TENDON SUBLUXATION 1037 Natural History Prompt, appropriate treatment can avoid pathologic changes in the peroneal tendon that occur from recurrent instability. 18 Untreated subluxation or dislocation can lead to redislocation, tendinitis, fraying, tearing, and rupture of the peroneal tendons, which can cause pain and disability. Arrowsmith et al. 1 were the first to describe in the English literature an association between chronic peroneal tendon instability and peroneus brevis fraying and tears. In their anatomic study of the SPR, Davis et al. 6 found that 14 of 30 specimens had various grades of attritional tendon pathology ranging from splaying to full thickness splits. All of the abnormal peroneal tendons had SPR insertional variants with one band of the SPR inserting onto the calcaneus. Redfern and Myerson 30 reported that the presence of peroneal tendon subluxation or dislocation, chronic ankle instability, or hindfoot varus deformity should alert the physician to the possibility of a peroneal tendon tear. 30 They stressed the importance of identifying these associations preoperatively and correcting all of them appropriately during surgery to prevent new peroneal tendon tears, loss of peroneal tendon strength, ankle instability, and progressive worsening of hindfoot varus. MANAGEMENT Acute Injuries Conservative treatment of acute peroneal tendon injuries has included cast immobilization, heel lifts to decrease tension on the tendons, taping, rehabilitation, and orthotics. Only small series with variable outcomes have been reported. 8,10,26,33 Sarmiento and Wolf 33 advocated cast immobilization for acute subluxations, but concluded that patients with chronic subluxations did better with surgical intervention. Oden 26 recommended that grades 1 and 3 injuries be treated with cast immobilization and grades 2 and 4 be treated operatively because these result in chronic subluxation. Eckart and Davis 8 reported that of four ankles treated with casting and three treated with strapping for 4 weeks, only one had a stable pain-free ankle. Although most grade 1 injuries were stable in a cast, it was not possible to identify those that were unstable. Escalas et al. 10 reported that 28 (74%) of 38 patients had no improvement after immobilization with a compression bandage for several weeks. 10 Because of the variable outcomes with conservative treatment, operative treatment appears to offer the best results for patients with acute peroneal tendon instability. For the operative treatment of acute lesions, Eckart and Davis 8 described direct suturing of the anterior retinacular edge to the fibrous lip or through drill holes in the malleolar ridge if the lip was avulsed for grades I and II injuries. Of their 61 patients, only three (5%) had redislocation. Arrowsmith et al. 1 reported no redislocations in three patients in whom they repaired the retinaculum and deepened the groove. Marti 17 primarily repaired the peroneal retinaculum in five patients and all were pain-free at an average of 3.5 years after surgery. In 12 patients with grade 3 injuries (avulsion of rim of cortical bone), Eckert and Davis repaired the fragment with Kirschner wires in 12 patients; at a minimal follow-up of 6 months, there were no dislocations. Murr 24 sutured the avulsed rim through drill holes in three skiers, all of whom were able to return to skiing without sequelae. Chronic Injuries Chronic, symptomatic subluxation or dislocation should be repaired surgically. 1,2 Reconstructive procedures are of three types: (1) rerouting of tendons, (2) soft-tissue repair or reconstruction, and (3) bony procedures. Tendon rerouting procedures involve substituting the calcaneofibular ligament for the incompetent peroneal retinaculum. Steinbock and Pinsger 39 reported good to excellent results in 12 patients at an average of 8.8 years after such tendon rerouting procedures. 39 Poll and Duijfjes 27 mobilized the calcaneal insertion of the calcaneofibular ligament with a small bone block, transposed the peroneal tendons, and reinserted the bone block with internal fixation. At 4 years after surgery, none of 10 patients had redislocations or instability and nine had returned to their original sports. Sarmiento and Wolf 33 described rerouting of the peroneal tendons under the calcaneofibular ligament with good results, and Martens et al. 16 reported normal clinical examinations, normal muscle power, and return to preoperative level of sports in nine of 11 patients treated with this procedure. Soft-tissue reconstruction can involve direct repair of the SPR or the use of local or transplanted tissues to reconstruct the retinaculum. Watson-Jones 42 described the use of an osteoperiosteal flap from the lateral cortex of the fibula to create a soft-tissue pedicle consisting of the SPR and fascia of the flexor hallucis longus. Various methods of tenoplasty have been described to create a new peroneal retinaculum. Jones 13 described using an Achilles tendon slip implanted on the lateral malleolus to act as a substitute for the ruptured SPR. Escalas et al. 10 reported that at 6.8- year average follow-up 14 of 15 patients treated with this technique were asymptomatic. Others also have reported good results with this procedure. 7,20 Other techniques of tenoplasty have used a portion of the peroneus brevis, 38 a portion of the peroneus quartus, 22 and a bifid peroneus brevis. 12 The SPR also can be reconstructed by modifications of procedures designed for lateral ankle instability. The Chrisman-Snook procedure has been modified so that the descending limb is passed laterally to the tendons, stabilizing them against the fibula. 37 Sobel et al. 37 reported excellent results with this technique in three patients who had lateral ankle instability with peroneal tendon subluxation. Arrowsmith et al. 1 used a modification of the Evans lateral ankle reconstruction in which the peroneus brevis tendon was divided proximally, passed through a drill hole in the fibula,

5 1038 OGAWA AND THORDARSON Foot & Ankle International/Vol. 28, No. 9/September 2007 looped around the peroneus longus tendon, and sutured to itself. No redislocations occurred in their two patients. Numerous bone block procedures have been described for the treatment of peroneal tendon dislocation. Kelly described making a sagittal cut in the lateral cortex of the fibula and rotating the bone block to enlarge the posterior lip. 14 McLennan 20 used a modification of this procedure in three patients and all were able to return to sports with two having excellent results. Others have used a modification of the Kelly procedure with good results and patients returning to previous athletic levels. 17,18 Micheli et al. 21 describedslidinga3cmlongx0.5cm wide cortical fibular graft distally 1 to 1.5 cm and securing it with 3.0-mm AO cortical screws to deepen the fibular groove while preserving the fibro-osseous tunnel to prevent scarring. They reported that 10 of their 11 young patients (average age 22 years) were able to return to previous athletic activities without re-dislocation. A risk of bone nonunion is possible with these procedures. Groove-deepening procedures can be technically difficult. 4 Zoellner and Clancy 43 described deepening the peroneal groove by elevating a bone flap, curetting cancellous bone, then tamping down the osteoperiosteal flap, which deepened the groove up to 8 mm. All nine of their patients had excellent results at 2-year followup with no recurrences or instability. Others also have reported high patient satisfaction rates with this procedure. 1,16 Porter et al. 28 recommended a groove-deepening procedure combined with SPR reconstruction. They removed a corticocancellous bone flap, deepened the distal posterior sulcus with a 4-mm burr, replaced the bone flap with the serosal surface toward the peroneal tendons, and secured the bone flap with resorbable suture. The lateral border was then roughened and the SPR was reattached. At an average followup of 35 months, eight of their 13 patients were able to return to preinjury levels of activity while five chose to return to lower levels of activity. Ankle and subtalar joint ranges of motion were near normal, and none of the patients complained of peroneal tendon discomfort or weakness. Postoperatively patients used a walking boot instead of cast immobilization, which the authors believed accelerated rehabilitation because it allowed early range of motion and immediate weightbearing. Shawen and Anderson 34 described a method of deepening the fibular groove which involves hollowing the bone beneath the posterior cortex of the fibula by inserting a drill in the tip of the fibula into the intramedullary canal and using a bone tamp to collapse the floor of the fibular groove; this is combined with repair of the SPR (Figure 6). They advocated this procedure because of its simplicity and the minimal postoperative pain and swelling. In a biomechanical cadaver study of pressure reduction after peroneal groove deepening by the method described by Zoellner and Clancy, 43 Title et al. 41 concluded that decompressing the peroneal tendons within the groove may diminish intratendinous stresses and may result in less pain and improved peroneal tendon function. They suggested that a combination of groove deepening and peroneal tendon debridement may be advantageous for treatment of partial peroneal tendon tears and tendinitis, two components of peroneal tendon instability. SUMMARY Peroneal tendon subluxation or dislocation is an uncommon problem that can result in longitudinal tearing of the peroneal tendons and significant morbidity if left untreated. Acute and chronic dislocations are best treated operatively with either tendon rerouting beneath the calcaneofibular ligament, soft-tissue repair or reconstruction alone, or bone-deepening procedures with repair of the retinaculum. Associated ankle instability, peroneal tendon tears, and hindfoot varus should be corrected at the time of treatment of the peroneal tendon dislocation. Almost all studies of operative treatment have reported good or excellent results in high percentages of patients. Unfortunately to our knowledge there is no study with a Level Fig. 5: Indirect groove-deepening technique.

6 Foot & Ankle International/Vol. 28, No. 9/September 2007 PERONEAL TENDON SUBLUXATION 1039 Table 2: Clinical studies of peroneal tendon subluxation and dislocation Name Year Level of evidence Number of ankles Treatment/Outcome/Key points Jones IV 1 Achilles tendon tenoplasty; patient able to return to collegiate football Sarmiento and Wolf IV 1 Rerouting under CFL by dividing the tendons; at 3 years normal strength, ROM, no further subluxation Eckert and Davis IV 73 Proposed classification of dislocation into 3 grades depending on severity; performed acute repair; found only elevated SPR (no tears); only 3 redislocated Grade II injuries. Marti IV 12 Modification of Kelly; no recurrent dislocation; two with persistent crepitation of tendons Zoellner and Clancy IV 9 Groove deepening with osteoperiosteal flap; all had shallow groove; all had excellent results Escalas et al IV 28 Jones procedure; 27/28 asymptomatic; suture band of tendon in dorsiflexion McLennan IV 3 Modified Kelly procedure; 2 with excellent results, 1 with good result but loose bodies in ankle Arrowsmith et al IV 6 3 acute and 3 chronic cases; different procedures by different surgeons; 5 without redislocation; all chronic cases had signs of peroneal tendon pathology Poll and Duijfjes IV 10 Peroneal tendons transposed under a cancellous bone block with CFL; 4 year followup, no redislocations, all felt improved, 9 returned to sport Das De and Balasubramaniam IV patients, compared Watson-Jones (3) 42, Jones (2) 13 vs. Periosteal flap repair (7); all 12 had Oden grade 3; none had a shallow fibular groove; none of 7 had redislocation Martens et al IV 11 Rerouting tendon under CFL; all with excellent or good results; 2 sural nerve paresthesias Oden IV Approximately 100 Added grade IV to Eckert and Davis classification; sutured torn SPR in grades II and IV; no redislocations reported; however, no follow-up evaluations were done Michelli et al IV 12 Sliding fibular bone graft; 91% excellent results Steinbock and Pinsger IV 13 Transposition under CFL; 11/13 excellent result; 9 different surgeons Kollias and Ferkel IV 12 Fibular grooving 43 ; 11/12 excellent results Shawen and Anderson IV Over 20 Fibular groove deepening; excellent results; minimal dissection and morbidity Porter et al IV 14 Groove deepening with cancellous bone flap and retinacular reconstruction; accelerated rehabilitation, early ROM and weightbearing; 35 month followup, no recurrent instability, no complications, all returned to some level of sport of Evidence higher than Level IV (Table 2). It is difficult to achieve a Level of Evidence I or II study of peroneal tendon subluxation and dislocation for two reasons: (1) there is no gold standard procedure to which to compare techniques and (2) no large series exist because peroneal tendon subluxation and dislocation are uncommon problems. Therefore, no treatment method can be given a grade other than I (insufficient evidence) and surgical

7 1040 OGAWA AND THORDARSON Foot & Ankle International/Vol. 28, No. 9/September 2007 decision-making is based primarily on the surgeon s experience and expertise. Acknowledgement The authors would like to thank Kirk K. Kurokawa for his illustrations. REFERENCES 1. Arrowsmith, S; Fleming, L; Allman, F: Traumatic dislocations of the peroneal tendons. Am. J. Sports Med. 11(3): , Brage, ME; Hansen, ST: Traumatic subluxation/dislocation of the peroneal tendons. Foot Ankle 13(7): , Butler, BW; Lanthier, J; Wertheimer, SJ: Subluxing peroneals: a review of the literature and case report. J. Foot Ankle Surg. 32: , Coughlin, MJ; Mann, R: Surgery of the Foot and Ankle, 7 th Ed. Vol. 2: St Louis, MO, Mosby, Dahm, DL; Kitaoka, HB: Peroneal tendon repair and reconstruction. Master techniques in orthopaedic surgery. The Foot and Ankle, 2 nd edition. 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