Keith L. Wapner, Selene G. Parekh, and Wen Chao
DEFINITION
Pathology of the peroneal tendons may cause chronic lateral ankle pain.1,3
Chronic lateral ankle pain can have many causes.
Isolated tears of the peroneus brevis and longus are rare, but fissuring and longitudinal splitting of the brevis and longus tendons have been reported as a cause of chronic ankle pain and functional instability.
Histologic evaluation of these splits has shown chronic wear with cystic and myxoid degeneration of the tendon.
When recognized early, direct repair is possible with good results.4,5
ANATOMY
The peroneus brevis tendon can be identified at the level of the lateral malleolus since it is closest to the malleolus.
The peroneus longus tendon is directly posterior to the brevis tendon.
Both the longus and brevis tendons are tethered at the level of the lateral malleolus by the superior peroneal retinaculum, which is a band of deep fascia that extends from the tip of the lateral malleolus to the calcaneus (FIG 1).
The tendons lie within the fibular groove; the most common location for longitudinal peroneus brevis tendon tears is at the fibular groove10 (FIG 2).
The flexor hallucis longus tendon (FHL) has a strength percentage of 3.6 and can substitute for the peroneus brevis muscle–tendon unit, which has a strength percentage of 2.6.
The FHL is an in-phase muscle with an axis of contracture similar to the peroneal muscle–tendon unit as it arises off the posterior fibula.
This technique inserts the FHL into the residual stump of the peroneus brevis tendon.
Our technique does not restore function of both peroneal tendons, since the distal portion of the peroneus longus tendon is too enmeshed in scar to serve as a viable insertion point for the FHL tendon.
PATHOGENESIS
The pathogenesis of chronic peroneal tendon ruptures is unclear. Many theories have been suggested, including a zone of critical hypovascularity,11 mechanical impingement from the fibular groove,6,9,12incompetence of the peroneal retinaculum,2,8 the presence of a sharp posterior fibular ridge,6,9,12 dynamic compression between the peroneus longus and brevis tendons,7 or the presence of a peroneus quartus muscle.13,14
NATURAL HISTORY
Patients typically present with advanced pathology of both tendons, such that neither can be salvaged in their entirety.
These patients tend to be middle-aged individuals who were active, working adults before their injuries. They will not wear bracing full-time or accept a surgical fusion of their hindfoot.
Most patients have a history of at least one failed surgical procedure to attempt a primary repair or anastomosis of the peroneus brevis and longus tendons.
The goal of this procedure is to provide dynamic stabilization of the ankle and restore the function of the peroneal tendons.
PATIENT HISTORY AND PHYSICAL FINDINGS
These patients present with chronic lateral ankle pain and tenderness, swelling, and lateral ankle instability.
Patients have considerable weakness and painful inversion and eversion compared with the contralateral limb.
A fully functional FHL tendon must be demonstrated.
Alignment of the affected lower extremity, including the hip, knee, tibia, ankle, hindfoot, and forefoot, must be assessed. A fixed hindfoot varus deformity may need to be corrected at the time of surgery.
If mechanical instability of the ankle is present, a ligament reconstruction at the time of the first stage can be included.
Muscle strength and balance should be evaluated, particularly inversion and eversion.
The single heel rise is helpful to evaluate the normal inversion–varus alignment of the hindfoot.
Manual muscle testing for FHL is helpful to evaluate the functionality and strength of the FHL motor unit.
The anterior drawer test is used in evaluating the integrity of the anterior talofibular ligament and the calcaneofibular ligament.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Weight-bearing ankle and foot radiographs must be obtained.
MRI of the involved ankle demonstrates chronic thickening, fissuring, scarring, and stenosis of the remaining peroneal structures (FIG 3A). Tears in the substance of the tendon and fluid in the sheaths may also be visualized (FIG 3B). Associated pathology of the ankle can be identified as well.
DIFFERENTIAL DIAGNOSIS
Fibular fracture, stress fracture
Peroneal tendon tear
Ankle instability, involving the anterior talofibular ligament or calcaneofibular ligament
Lateral process fracture of the talus
Syndesmosis or subtalar sprains
Impingement lesions
Osteochondral lesions of the talus
Tarsal coalition
FIG 1 • The peroneus longus and brevis tendons are tethered at the level of the lateral malleolus by the superior peroneal retinaculum, which extends from the tip of the lateral malleolus to the calcaneus. (Source: Moore KL, Dalley AF. Clinically Oriented Anatomy, 4th ed. Philadelphia: Lippincott Williams & Wilkins, 1999.)
NONOPERATIVE MANAGEMENT
Functional rehabilitation includes range of motion for the ankle and hindfoot, concentric and eccentric muscle strengthening, endurance training with particular attention to the peroneal musculature, and proprioceptive training.
Proprioceptive exercises improve dynamic stability and are an essential part of the rehabilitation program.
Functional bracing or taping may be useful to help prevent recurrent injury during “at-risk” activities.
SURGICAL MANAGEMENT
The technique is staged in two parts. During each stage, the patient is positioned in the same manner. Perioperative antibiotics are given. A pneumatic thigh tourniquet is applied as needed.
Preoperative Planning
All imaging studies must be reviewed.
Plain films must be reviewed for degenerative changes, malalignment, fractures, and the presence of hardware from previous surgeries.
Positioning
The patient is placed supine on the operating table. Some prefer to place the patient on a beanbag and approach the lateral aspect of the ankle in a lazy lateral or lateral decubitus position. We place saline bags under the ipsilateral hip to achieve this lazy lateral position.
FIG 2 • Intraoperative photograph of a longitudinal peroneus brevis tear located in the fibular groove.
FIG 3 • Axial T2 MRI image demonstrating (A) a tear in the peroneal tendon and (B) fluid around the sheath of the tendon.
Approach
A longitudinal incision is centered over the course of the peroneal tendons, beginning 1 cm posterior and proximal to the tip of the fibula.
The incision is extended to the base of the fifth metatarsal (FIG 4).
FIG 4 • Intraoperative photograph demonstrating the peroneal incision, from over the peroneals to the base of the fifth metatarsal.
FIG 5 • Extensive scar tissue is evident overlying the peroneal tendons in this multiply operated patient.
Care must be taken to protect the sural nerve in the distal aspect of the incision, which is subcutaneous and just posterior to the incision.
The surgeon carefully dissects through the extensive scar tissue (FIG 5).
TECHNIQUES
STAGE 1: DÉBRIDING THE PERONEAL TENDON AND SHEATH REMNANTS
If present, identify the peroneal sheath. Incise the sheath proximally through the superior peroneal retinaculum to the musculotendinous junction. Distally, open the sheath as far as needed.
The first stage of reconstruction consists of débriding the remaining peroneal tendon tissue and the tendon sheath (TECH FIG 1).
TECH FIG 1 • The peroneal tendon sheath and tendon are débrided.
STAGE 1: INSERTING THE HUNTER ROD
Insert a 6–mm Hunter rod into the bed of the peroneal sheath. Suture the Hunter rod to the remaining stump of the peroneus brevis tendon distally with nonabsorbable suture. Proximally, the rod remains free in the sheath. (TECH FIG 2).
TECH FIG 2 • A 6-mm Hunter rod is placed into the bed of the peroneal sheath. The Hunter rod is sutured into the remaining stump of the peroneus brevis tendon distally with nonabsorbable suture. Proximally, the rod remains free in the sheath.
Trim the sheath of any redundancy and close it over the Hunter rod (TECH FIG 3).
TECH FIG 3 • The sheath is trimmed of any redundancy and closed over the Hunter rod.
STAGE 2: HARVESTING THE FHL
Make an incision along the medial border of the midfoot, just above the level of the abductor muscle, from the navicular to the head of the first metatarsal.
Identify the abductor hallucis fascia and reflect the abductor muscle plantarly.
Place a small Weitlaner retractor in the wound and reflect the flexor hallucis brevis plantarward as well. Release the origin of this muscle.
Identify the FHL and flexor digitorum longus (FDL) tendons within the midfoot. This is facilitated by placing a finger over the lateral aspect of the short flexors and plantarflexing and dorsiflexing the hallux interphalangeal joint.
Release the FHL as far distally as possible, generally at the level of the midshaft of the first metatarsal. An adequate distal stump of the FHL must be maintained to suture the distal stump to the FDL tendon with all five toes in a neutral posture. It is important to stay within the second muscle layer of the foot deep to the fat pad that overlies the neurovascular structures that sit just plantar to the long tendons.
Tag the proximal stump of the FHL with a suture.
STAGE 2: EXCHANGING THE HUNTER ROD FOR THE FHL TENDON
With the FHL harvested, make a small incision at the proximal aspect of the previously made lateral incision overlying the proximal aspect of the Hunter rod, staying proximal to the lateral malleolus.
Identify the FHL in the deep posterior compartment at its origin on the posterior fibula. Pull it into the lateral incision (TECH FIG 4).
TECH FIG 4 • After the flexor hallucis longus is released from the plantar surface of the foot, it is identified in the deep posterior compartment at its origin on the posterior fibula. It is then pulled into the lateral incision.
Identify the proximal portion of the Hunter rod and attach the FHL to the proximal aspect of the Hunter rod.
Make a small distal incision over the distal suture site of the Hunter rod and the remaining portion of the peroneus brevis (TECH FIG 5).
TECH FIG 5 • A small distal incision is made over the distal suture site of the Hunter rod and the remaining portion of the peroneus brevis.
Release the Hunter rod from this suture site and pull it distally, allowing the FHL tendon to slide into the newly formed tendon sheath.
Attach the FHL to the remaining stump of the peroneus brevis tendon using a Pulvertaft weave (TECH FIG 6).
TECH FIG 6 • The flexor hallucis longus is attached to the remaining stump of the peroneus brevis tendon using a Pulvertaft weave.
POSTOPERATIVE CARE
Postoperatively, after the insertion of the Hunter rod, patients are initially placed in a bulky Jones dressing for the first 2 weeks. Thereafter, they are allowed to bear weight as tolerated in a removable short-leg walking boot. They are instructed to remove the boot four times a day and perform active and passive range-of-motion exercises of the ankle and hindfoot in all planes of motion.
Three months after the Hunter rod placement, the patient is brought back to the operating room for a transfer of the FHL tendon. Postoperatively, again, he or she is placed in a bulky Jones-type dressing for 2 weeks. Thereafter, the patient is advanced to a removable short-leg cast walker and maintained non–weight-bearing until 4 weeks. From week 4 to week 8, the patient is advanced to partial weight bearing in a removable cast walker. The patient is instructed to begin active and passive range-of-motion exercises of the ankle and hindfoot in all planes of motion. Home strengthening exercises are begun at 8 weeks, and the patient is advanced to an ankle stirrup at 12 to 14 weeks based on his or her strength. All patients are enrolled in formal physical therapy for functional rehabilitation of the ankle starting at 8 weeks.
OUTCOMES
Data on the 8-year follow-up of seven patients has been published by the senior author (KLW). All wounds healed without complications. One workers' compensation patient had continued pain and ambulates with a molded ankle–foot orthosis. The remaining six patients report complete relief of preoperative symptoms and a return to preinjury levels of activity. There were five excellent results, one good result, and one fair result.15,16
COMPLICATIONS
Wound complications
Sural nerve injury
Chronic pain
REFERENCES
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