Given the challenges of treating subluxing peroneal tendons, this author discusses the use of a semitendinosus graft to address this condition in two patients with ankle sprains.
Peroneal tendon subluxation/dislocations, although not rare, are relatively uncommon and often misdiagnosed. Acute dislocations are often unrecognized and misdiagnosed as ankle sprains, and lead to chronic instability. Most acute conditions are sports-related injuries stemming from soccer, football, basketball, running and skiing. Violent traumas such as car accidents and falls from a height are usually associated with fractures of the fibula, talus and calcaneus. Iatrogenic subluxing peroneal tendon injuries can result from poorly performed surgery as well.
At the ankle, the peroneal tendon courses through a fibro-osseous tunnel at the level of the distal fibula. It is bordered anteriorly by the posterior surface of the fibula, medially by the posterior talofibular ligament, posterior inferior tibiofibular ligament and calcaneofibular ligament, and posterolaterally by the superior peroneal retinaculum. The peroneal tendons are also enveloped in a synovial sheath that extends from the distal peroneal muscle to the distal 2 cm of the fibula. There the fibula combines with the fascia of the calf to form the superior peroneal retinaculum, which becomes the primary restraint to subluxation.1,2 The groove located in the posterior portion of the fibula can be flat or even convex, leading to instability of the peroneal tendons.
What You Should Know About The Mechanism And Grading Of Injury
Disruption or tear of the superior peroneal retinaculum has been implicated in peroneal tendon dislocations, but this is usually more iatrogenic. More commonly, the retinaculum is avulsed or stripped off the fibula. The mechanism of injury is typically a sudden dorsiflexion and inversion of the ankle with forceful contraction of the peroneal musculature. Concomitant rupture of the calcaneofibular ligament is also present. Chronic subluxation occurs in recurrent ankle sprains with instability. We can grade peroneal tendon injuries as follows:1
Grade I: The retinaculum is elevated from the lateral malleolus with the tendons lying between the bone and periosteum.
Grade II: The fibrocartilaginous ridge is elevated with the retinaculum attached and the tendons are displaced beneath the ridge.
Grade III: A thin cortical fragment is avulsed from the fibula with the tendons displaced beneath the fibular fragment.
Grade IV: The retinaculum is avulsed or ruptured from the posterior attachment.
A 43-year-old female presented after slipping on wet hay and falling off a low lying wall while tending to horses in her stable. She suffered an inversion sprain and peroneal tendon injury to her right ankle. The patient sought treatment from another physician who repaired a torn peroneal longus tendon with a tissue graft. The superficial peroneal retinaculum did not close well primarily and the patient developed increased pain posterior to the ankle when she began weightbearing at six weeks.
During the physical examination of the patient, I noted edema and pain to the peroneal tendons. Dorsiflexion and circumduction of the ankle produced a visible and painful subluxation of the peroneal brevis tendon. Magnetic resonance imaging (MRI) confirmed a subluxed peroneal brevis tendon.
Historically, conservative therapy is not very effective. Conservative therapy usually consists of non-weightbearing casts for two weeks followed by bracing and physical therapy. I elected surgical repair for this patient. Intraoperative examination confirmed degradation of the retinaculum and it was not amenable to repair. I removed the soft tissue graft from the peroneal tendon and removed the Prolene sutures (Ethicon) as well. The peroneal tendon did not appear to be damaged in any way. There were no signs of tenosynovitis or tendinosis.
I created a sling to house the peroneal tendons in the fibrous tunnel. I created drill holes in the distal fibula at approximately 90-degree angles to each other. I shuttled a 5 mm x 100 mm pre-sutured semitendinosus graft (Musculoskeletal Transplant Foundation) into the tunnel and applied fixation with two 5x15 mm G-Force Tenodesis System anchors (Wright Medical).
The patient was non-weightbearing in a cast for three weeks and then ambulated in an articulating ankle brace and sneakers. I consulted a sports physical therapist for rehabilitation. She returned to full activity and riding horses by 12 weeks in the articulating brace. By six months, she no longer wore the brace and was pain-free with all activity. The patient continues to do well 18 months after the procedure.
The second patient is a 16-year-old female who sustained an ankle sprain during softball. Another physician treated her for three months with physical therapy and bracing. My physical examination showed subluxing peroneal tendons with circumduction of the right ankle. She had pain and edema to the lateral ankle. The MRI revealed subluxing peroneal tendons and rupture of the anterior talofibular ligament. An intra-operative examination confirmed the diagnosis of Grade II subluxing peroneal tendons with the peroneal brevis tendon lying over the fibula.
Since this is a high-level athlete, I decided to perform the aforementioned procedure utilizing a semitendinosus graft and performed a modified Brostrom repair of the anterior talofibular ligament.
This patient had the same postoperative protocol as the first patient. She was jogging at nine weeks and running at 12 weeks. She returned to softball in the articulating brace at 15 weeks. At the 12-month follow-up, the patient was pain-free and functioning well.
Authors have described many techniques to address subluxing peroneal tendons. Direct reattachment of the superficial peroneal retinaculum to the fibula with multiple drill holes, various bone block procedures, tissue transfers and tendon rerouting procedures all work well. However, there is some degree of limitation of motion associated with these techniques. This novel technique, similar to a Chrisman-Snook lateral ankle stabilization utilizing a tissue graft, is especially good when the superficial peroneal retinaculum is inherently weak from prolonged inflammation or destroyed from previous surgery. A byproduct of this procedure is stabilization of the lateral ankle ligaments as well. To date, these patients are functioning well to pre-injury levels.
Dr. Batelli is in private practice in Totowa, NJ. He is a Fellow of the American College of Foot and Ankle Surgeons. Dr. Batelli is board-certified in foot surgery and reconstructive rearfoot and ankle surgery.
1. Coughlin M, Mann R, Saltzman C. Surgery of the Foot and Ankle, Eighth Edition. Mosby, St. Louis, 2007, pp. 1209-1220.
2. Mendeszoon M, McVey JT, MacEvoy A. Surgical correction of subluxing peroneal tendons utilizing a lateral slip if the Achilles tendon: A case report. Foot Ankle Online J. 2009; 2(8):3.
3. McAlister JE, Philbin TM. How to manage peroneal tendon subluxation. Podiatry Today. 2013; 26(9):62-71.
4. VanPelt MD, Landrum MR, Igbinigie M, et al. Kinematic magnetic resonance imaging of peroneal tendon subluxation with intraoperative correlation. J Foot Ankle Surg. 2017; 56(2):395-397.