DEFINITION

Peroneal tendon subluxation or dislocation from the retrofibular groove is a rare cause of ankle pain and disability. The acute injury often remains unrecognized or is misdiagnosed as an ankle sprain.

Untreated or misdiagnosed acute injury predisposes a patient to recurrent peroneal dislocation, potential peroneal tendon tear, or chronic dislocation.

 

 

ANATOMY

 

The peroneus longus and brevis muscles are the two major structures within the lateral compartment of the leg, both arising from the proximal fibula (FIG 1A).

 

Both structures become tendinous before crossing the ankle joint and remain in a common sheath. As they course distally, the tendon of the peroneus brevis lies against the posterior surface of the distal fibula, anterior and medial to the tendon of the peroneus longus.

 

Distal to the fibula, each tendon enters a distinct tendon sheath, separated by the peroneal tubercle.

 

Posterior to the distal fibula, both tendons are stabilized in the retrofibular groove by the superior peroneal retinaculum (SPR) (FIG 1B).

 

The posterior surface of the distal fibula is covered by a layer of fibrocartilage to allow smooth gliding of the peroneal tendons. The depth and width of the retrofibular (peroneal) groove is highly variable. A definite groove

is present in about 80%. In the remaining cases, the posterior surface of the fibula is flat or convex.5 A fibrocartilage rim on the lateral border of the fibula that adds an additional 2 to 4 mm to the depth of the sulcus is often present.

 

 

 

FIG 1 • A. Lateral view of the ankle showing the peroneal tendons as well as the superior and inferior peroneal retinacula. Note the vertical orientation of a portion of the SPR that corresponds to the orientation of the

calcaneofibular ligament. B. Superior view of the ankle region shows the relationship of the fibular groove, SPR, peroneal tendons, and cartilaginous ridge. (A: From Davis WH, Sobel M, Deland J, et al. The superior peroneal retinaculum: an anatomic study. Foot Ankle Int 1994;15:273; B: From Coughlin MJ, Mann RA, eds. Surgery of the Foot and Ankle, ed 7. St. Louis: Mosby, 1999:819.)

 

 

The SPR, the primary restraint to peroneal instability, is composed of a band of the deep fascia that is continuous with the periosteum of the distal fibula but does not attach to the fibrocartilage rim or the

 

posterolateral edge of the bone.11 It is extremely variable in width and thickness, and five distinct insertional patterns have been described, the most common being a band to both the Achilles tendon and the calcaneus.3 The fiber orientation of the SPR is parallel to those of the calcaneofibular ligament, and therefore inversion

injuries of the calcaneofibular ligament may also cause injury to the SPR.6,9

 

PATHOGENESIS

 

Acute subluxation or dislocation of the peroneal tendons usually occurs while the foot is forcefully dorsiflexed with the peroneal muscles strongly contracted; it commonly occurs during a forward fall in Alpine skiing or in

springboard diving.8

 

Resisted plantarflexion and inversion while the peroneals contract may also cause subluxation or dislocation of the peroneal tendons, and in this case, it is commonly associated with lateral instability of the ankle.

 

 

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Peroneal dislocation may also occur as a sequela to severe calcaneal fractures with lateral displacement of the calcaneus.5,7

 

Peroneal dislocations can be classified into three grades depending on the pathoanatomy of the injury4:

 

 

Grade I: SPR stripped off fibula; peroneus longus dislocated anteriorly

 

Grade II: fibrous rim avulsed from posterolateral aspect of fibula along with SPR; peroneus longus dislocated anteriorly

 

Grade III: bony rim avulsion fracture attached to SPR with anterior dislocation of peroneus longus

 

As a result of subluxation or dislocation, inherent injuries to the tendons can occur. Depending on the location of the tendon injury, they are divided into zones I, II, and III.

 

 

Zone I injuries are defined as those involving the fibular groove and most often affect the peroneus brevis tendon. As the tendons sublux in the groove, the brevis is forced onto the sharp posterolateral bony ridge of the distal fibula, causing a longitudinal split in the tendon from the strain of a 45-degree course change as well as compression by the overlying longus tendon.

 

Zone II injuries are located between the tip of the fibula and the cuboid tunnel.

 

Zone III injuries are located in the cuboid tunnel and primarily involve the peroneus longus tendon and possibly a painful os peroneum.

 

NATURAL HISTORY

 

If diagnosed early, in acute peroneal dislocation, the tendons can be manually reduced and held in a reduced position for a 4- to 6-week period of immobilization. In this situation, functional rehabilitation leads to

maintenance of tendon reduction and complete recovery in about 50% of cases.1

 

With delayed diagnosis and treatment, recurrent subluxation and chronic dislocation are common and may lead

to degeneration and tearing of the peroneal tendons.10

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Most patients present well beyond the acute phase complaining of vague posterolateral ankle pain that radiates proximally with or without a popping sensation during activity.12

 

 

There may be a history of forced dorsiflexion trauma associated with a pop on the lateral aspect of the ankle. Often, a history of an inversion-supination sprain and possible lateral ankle instability is reported.9

 

On physical examination, peroneal tendinopathy is characterized as fullness along the tendons with diffuse

tenderness. Localized tenderness over the posterior ridge of the fibula should raise suspicion for progression of the injury to a peroneal tendon split tear.

 

Pain may be elicited with inversion stretch or active resisted eversion.

 

Tendon subluxation typically presents as snapping or popping and pain with eversion against resistance. The peroneal tunnel compression test consists of having the patient perform this motion while palpating the posterior border of the fibula. Circumduction of the ankle may demonstrate dislocation of the tendons with eversion and dorsiflexion and spontaneous relocation with plantarflexion and inversion (FIG 2).

 

 

 

FIG 2 • Dislocated peroneal tendons during resisted eversion.

 

 

Chronic dislocation of the tendons is characterized by a palpable ridge over the lateral distal fibula often associated with chronic swelling.

 

Eversion strength may be limited by pain. Significant weakness of active eversion without much pain should

raise suspicion for a complete tear of the peroneal tendons.

 

A complete examination of the ankle should also include evaluation of associated injuries, ruling out differential diagnoses. This includes (but is not limited to) the following:

 

 

Lateral ankle instability: history of frequent sprains, cavovarus foot, increased laxity with anterior drawer or inversion stress test compared to the contralateral side

 

High ankle sprain (syndesmotic sprain): pain over anterior ankle syndesmosis, pain with provocative maneuvers (calf squeeze test, external rotation stress test)

 

Painful os trigonum or posterior talar process fracture: pain with forced plantarflexion, pain with resisted plantarflexion of the great toe

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Plain radiographs including anteroposterior (AP), mortise, and lateral views of the ankle should be obtained to rule out fracture or large osteochondral defects of the talus.

 

Occasionally, a “fleck” sign, an avulsion fracture off the posterior distal fibula, can be seen on AP or mortise

views. If present, this is considered pathognomonic for a grade III injury to the SPR with peroneal dislocation.4 As shown in FIG 3A, this may be difficult to see without the use of a “hot lamp.”

 

Stress views may be helpful to rule out lateral ankle instability.

 

Computed tomography (CT) may be helpful in uncertain diagnosis to evaluate the anatomy of the fibular groove

and detect small avulsion fractures, which may be difficult to see on plain films2 (FIG 3B). Axial CT scan images may also confirm peroneal tendon dislocation.

 

Magnetic resonance imaging (MRI) can identify injury to the SPR, subluxated or dislocated tendons, and intrasubstance degeneration and split tears of the tendons (FIG 3C,D).

 

Ultrasound, although operator-dependent, allows a dynamic, real-time examination to evaluate subluxation during provocative maneuvers.

 

 

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FIG 3 • A. AP radiograph of the ankle under a hot lamp shows a lateral rim fracture off the distal fibula (fleck sign, circle). B. Axial CT scan shows a grade III injury with an avulsion fracture of the lateral edge of the distal fibula (fleck sign, arrow) and dislocated peroneal tendon (asterisk). C,D. T1- and T2-weighted axial magnetic resonance images, respectively, show dislocated peroneal tendons (arrow) with abundant tenosynovitis. Note the shallow retrofibular groove and the torn SPR.

 

DIFFERENTIAL DIAGNOSIS

 

 

Peroneal tendinopathy or tears Lateral ankle instability

 

High ankle sprain

 

Osteochondral defect of the talus

 

 

Painful os trigonum or posterior talar process fracture Retrocalcaneal bursitis

NONOPERATIVE MANAGEMENT

 

Acute peroneal subluxation or dislocation can be treated nonoperatively if the peroneal tendons can be reduced and held in a reduced position.

 

In this case, treatment consists of short-leg cast immobilization in slight plantarflexion and inversion for 4 to 6 weeks, followed by functional rehabilitation. U- or J-shaped foam or felt pads can be placed in the cast to apply pressure around the distal fibula and maintain the position of the peroneal tendons.

 

In our opinion, there is no role for nonoperative treatment for symptomatic chronic peroneal dislocation or

recurrent subluxation.

 

SURGICAL MANAGEMENT

 

All irreducible peroneal tendon dislocations and those associated with a rim avulsion fibular fracture should be considered for acute surgical reduction and repair.

 

 

Operative treatment is also indicated for all chronic injuries in patients with pain or functional limitations. Five basic categories of repair have been described8:

 

Anatomic reattachment of the retinaculum

 

Bone block procedures

 

 

 

Reinforcement of the SPR with local tissue transfers Rerouting of the tendons behind the calcaneofibular ligament Groove-deepening procedures

 

The goal of groove-deepening procedures is to increase the height of the posterolateral fibular rim to prevent the peroneal tendons from subluxating.

 

General contraindications to surgical intervention include peripheral vascular disease, skin breakdown or vasculitis, and patients who are “voluntary” subluxators. These are usually patients with generalized ligamentous laxity. Physical examination usually shows the peroneal tendons to subluxate to the lateral rim of the fibula on both ankles but not over it.

 

Preoperative Planning

 

We recommend reviewing all imaging studies preoperatively to plan for not only fibular groove deepening but also any procedures to address associated pathology. Plain films should be reviewed for fractures, loose bodies, ankle and foot alignment, and the presence of any hardware (from previous procedures).

 

Associated fractures, osteochondral lesions, and lateral ankle instability should be addressed concurrently.

 

We routinely perform an examination under anesthesia on the operating table before making an incision to assess the ankle and subtalar joint. The peroneal tendons may also be

 

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assessed under anesthesia, but without the patient being able to evert against resistance, this is of limited value.

 

Positioning

 

The procedure is performed with the patient in the semilateral position.

 

A beanbag is used to maintain the position of the body with a 10-pound sandbag underneath the ipsilateral hip.

 

 

This allows the physician to readily access the posterior fibula and obtain fluoroscopic AP and lateral views of the ankle without moving the C-arm from the standard AP position.

 

Regional or general anesthesia can be used, and a thigh tourniquet is applied.

 

Approach

 

The standard surgical approach is through a longitudinal, curvilinear incision on the posterior aspect of the fibula following the course of the peroneal tendons to roughly the level of the peroneal tubercle (FIG 4).

 

This allows excellent visualization of the SPR, the peroneal tendons, and the posterior aspect of the distal fibula

and also provides sufficient access to the lateral tibiotalar joint in cases where concomitant lateral ligament reconstruction is indicated.

 

 

 

FIG 4 • Utilitarian posterolateral approach for peroneal repair and indirect fibular groove deepening.

 

 

If lateral ankle instability and injury to the peroneal tendons distally have been ruled out preoperatively or with the examination under anesthesia, the approach can be limited to a longitudinal incision just posterior to the fibula.

 

TECHNIQUES

• Indirect Fibular Groove Deepening

Exposure

Make a curvilinear incision along the posterior aspect of the distal fibula. It extends toward the base of the fifth metatarsal but usually ends at the level of the peroneal tubercle.

Develop full-thickness skin flaps to avoid skin necrosis.

Protect the sural nerve and branches of the superficial peroneal nerve.

 

 

 

 

TECH FIG 1 • A. The superior peroneal retinaculum (SPR) is incised longitudinally and retracted with two hemostats. A longitudinal split tear of the peroneus brevis tendon (PBT) is often identified in chronic dislocations. PLT, peroneus longus tendon. B. Split tears of the PBT are débrided or repaired. C. The low-lying peroneus brevis muscle and, if present, the peroneus quartus (PQT) are excised to create room for the peroneal tendons.

 

 

Incise the peroneal sheath distal to the fibula.

 

If the SPR is still intact, incise it over the bone and then sharply elevate it off the fibula, leaving a cuff of tissue on the distal fibula. Retract the edges of the SPR posteriorly with two small hemostats to facilitate later repair.

Peroneal Preparation

 

Inspect the peroneal tendons, excise inflamed tenosynovium, and débride and repair split tears in the tendons with buried nonabsorbable suture (TECH FIG 1A,B).

 

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Excise any low-lying peroneus brevis muscle from the tendon. Also excise a normal anatomic variant, the peroneus quartus, a supernumerary muscle of the lateral compartment of the leg, if present.

 

These additional procedures tend to make room in the groove for the peroneal tendons (TECH FIG 1C).

Deepening the Groove

 

Expose the distal fibular tip, avoiding injury to the calcaneofibular ligament.

 

Place an intramedullary guide pin from distal to proximal inside the fibula, in line with the posterior cortex (TECH FIG 2A).

 

Thin the posterior cortex by sequential reaming over the guidewire (usually 7 to 8 mm) (TECH FIG 2B,C).13

 

We routinely use suitably sized reamers from the Bio-Tenodesis Screw System (Arthrex, Inc., Naples, FL) or any anterior cruciate ligament instrument set.

 

 

 

TECH FIG 2 • A. An intramedullary guide pin is placed into the distal fibula parallel to the posterior cortex. B. The posterior cortex of the fibula is thinned by intramedullary reaming with cannulated reamers over the guide pin. C. Technique for indirect fibular groove deepening. D. The posterior cortex of the fibula is impacted into the void created by the reamers with an appropriate-sized tamp. E. To avoid fracture of the edge of the fibula during impaction, the posterolateral cortex is perforated with an osteotome (this is necessary only in very hard bone).

 

 

Alternatively, consider using progressively larger drill bits from a standard trauma set or cannulated drills from a dedicated fifth metatarsal (Jones fracture) set (Wright Medical Technology, Memphis, TN).

 

Once the posterior cortex is sufficiently thinned, impact it into the void created by the reamers using an appropriately sized bone tamp (TECH FIG 2D). This preserves the physiologic gliding surface covering the groove, making it a smooth bed for tendon excursion.

 

If the bone is very hard and impaction cannot be performed easily, the posterolateral cortex of the fibula can be perforated with an osteotome or microsagittal saw to facilitate impaction of the posterior cortex (TECH FIG 2E).

 

Also tamp the very distal tip of the fibula inward to avoid a sharp edge that would otherwise impinge on the peroneal tendon as it courses into the foot.

 

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When done correctly, the entire peroneus brevis and at least 50% of the peroneus longus tendon should be covered by the fibular rim with the tendons in a resting position.

Superior Peroneal Retinaculum Repair

 

After completing groove deepening, tendon débridement, and tendon repair, repair the SPR.

 

Sharply elevate the remainder of the cuff on the fibula off bone, exposing the lateral cortex, which is then roughened to bleeding bone with a rasp or rongeur.

 

Excise any redundant SPR tissue and advance the remaining SPR to the previously prepared cortical bed; secure it through either drill holes or suture anchors.

 

 

 

TECH FIG 3 • After deepening of the retrofibular groove, the lateral cortex of the fibula is roughened with a rongeur or rasp and the superior peroneal retinaculum (SPR) is repaired. A. Six drill holes are created in the posterolateral edge of the fibula (alternatively two or three suture anchors can be used). B,C. The SPR is then repaired to the distal fibula with 2-0 suture in a pantsover-vest fashion.

 

 

Place three or four drill holes or suture anchors about 1 cm apart proximally from the tip of the fibula (TECH FIG 3A).

 

Reattach the posterior flap of the SPR to the prepared bone with 2-0 suture in a “pants-over-vest” technique, making sure that the space between the bony surface of the lateral malleolus and the SPR is obliterated.

 

 

Suture the anterior portion of the retinaculum over the repair with interrupted 2-0 suture (TECH FIG 3B,C). Test the stability of the repair by ranging the ankle through a full range of motion.

 

Verify free excursion of reduced tendons; the tendons should not be trapped by the repair.

Overtightening of the SPR repair is not necessary; the goal is to keep the peroneal tendons reduced posterior to the fibula.

 

 

Avoid surgery on voluntary

dislocators.

• High risk of recurrence

Maintain the operated limb

in a semilateral position (use a large bump under the ipsilateral hip or a beanbag).

• It is difficult to gain access to the posterior aspect of the fibula with

the patient in a supine position.

Incise the SPR on the

posterior margin of the fibula, not too far posteriorly.

• This allows excision of redundant tissue and a secure SPR repair to

bone.

Create adequate room for

the peroneal tendons.

• Excise all low-lying peroneus brevis muscle and the entire peroneus

quartus if present.

Inspect both peroneal

tendons for tears.

• Débride and repair as necessary

Avoid fibular stress

fracture.

• Reaming the fibula may not weaken the posterior fibula adequately,

particularly in young, healthy patients with good bone quality. Weaken the posterior fibular cortex with an osteotome or microsagittal saw before impaction to control the fibular groove deepening.

Avoid creating stenosis of

the peroneal tendons when repairing the SPR.

• Observe satisfactory tendon excursion with ankle and hindfoot

range of motion after SPR repair.

 

PEARLS AND PITFALLS

 

 

 

POSTOPERATIVE CARE

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Immediately postoperatively, the leg and ankle are placed into a posterior and U-splint in neutral position and the patient is kept non-weight bearing for 2 weeks.

 

Sutures are removed at 2 weeks. A short-leg walking cast is applied and the patient is allowed to bear weight as tolerated.

 

At 6 weeks, the cast is removed and a cam walker boot is applied to avoid ankle inversion while allowing plantarflexion and dorsiflexion. Active range-of-motion exercises are initiated at that time.

 

Peroneal strengthening is started at about 8 to 10 weeks after surgery.

 

Full return to activities is expected between 4 and 6 months postoperatively.

 

In elite athletes, given a stable reconstruction, we have been more aggressive with the rehabilitation to include biking and pool activities by 4 weeks.

 

OUTCOMES

As many variations of fibular groove-deepening techniques have been described, all reported results in the literature are derived from small retrospective series. There are no published prospective randomized studies comparing different surgical techniques.

In general, results of fibular groove-deepening techniques have been good as long as the underlying pathology is correctly addressed.8

In our hands, indirect grooving has provided excellent overall results while minimizing the surgical dissection and morbidity. We have not had recurrent dislocations using this technique.

We recommend that fibular groove deepening should be performed with every SPR reconstruction for chronic peroneal dislocation.

 

 

COMPLICATIONS

Infection

Delayed wound healing Sural nerve injury Recurrent dislocation Loss of motion

 

 

REFERENCES

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4. Eckert WR, Davis EA Jr. Acute rupture of the peroneal retinaculum. J Bone Joint Surg Am 1976;58(5):670-672.

    

    

5. Edwards M. The relations of the peroneal tendons to the fibula, calcaneus, and cuboideum. Am J Anat 1927;42:213-252.

    

    

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7. Karlsson J, Eriksson BI, Sward L. Recurrent dislocation of the peroneal tendons. Scand J Med Sci Sports 1996;6:242-246.

    

    

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11. Niemi WJ, Savidakis J Jr, DeJesus JM. Peroneal subluxation: a comprehensive review of the literature with case presentations. J Foot Ankle Surg 1997;36:141-145.

     

     

12. Sammarco GJ. Peroneal tendon injuries. Orthop Clin North Am 1994; 25:135-145.

     

     

13. Shawen SB, Anderson RB. Indirect groove deepening in the management of chronic peroneal tendon dislocation. Tech Foot Ankle Surg 2004;3(2):118-125.