Specific peroneal tendon injuries and treatment are beyond the scope of this article but peroneus brevis tears (zone 1) occur in the retromalleolar groove and peroneus longus tendon tears (zone 2) occur within the cuboid tunnel.25 In their small series, Rosenberg and colleagues compared preoperative MRI evaluations to intraoperative findings.26 The authors identified eight true positives and one false positive, noting that the lateral fibular attachment is often thickened and difficult to differentiate from subcutaneous tissue. They concluded that superior peroneal retinacular injuries might be present in the face of normally positioned peroneal tendons.
These imaging modalities are great adjuncts but the proper diagnosis should occur clinically prior to imaging.
A Primer On Classifications Of Superior Peroneal Retinacular Injuries
Eckart and Davis described the most common classification for superior peroneal retinacular injuries in 1976.27 They reported on three types of injuries. Grade I injuries (51 percent) involved elevation of the retinaculum from the lateral malleolus, allowing the tendons to dislocate between bone and periosteum. Grade II injuries (33 percent) occurred when a fibrocartilaginous ridge was elevated with the retinaculum and the tendons subluxed between it and the fibula. Grade III injuries (16 percent) occurred with a small cortical fibular avulsion along with the retinaculum.
In 1987, Oden modified a grade II tear to be a retinacular tear as opposed to a periosteal elevation.28 The author added a grade IV injury pattern as a tear of the superior peroneal retinaculum from its posterior attachment.
What The Literature Says About Treatment
The management of peroneal tendon subluxation and instability is primarily based on a mechanical versus a functional mechanism. When the superior peroneal retinaculum is torn or elevated with or without a fragment of periosteum or bone, and the tendon(s) are unstable, the prevailing theory is to perform a direct repair of the superior peroneal retinaculum and secondarily assess the retromalleolar groove for concavity and deepen as necessary.
Acute injury treatment often includes a period of immobilization in a short-leg cast with the foot in a plantarflexed and inverted position to allow for the tendons to be in a relaxed position for six weeks. An aggressive physiotherapy program typically follows this period of immobilization.
Despite this, Escalas and coworkers reported that only 26 percent (10 of 38) of their acute cases improved after compression bandaging and immobilization.29 Eckert and Davis also determined through a treatment cohort comparison that it is not possible to determine the long-term stability of conservative treatment in acute injuries.27 Chronic injuries typically fail conservative treatment and there has been a success rate of less than 50 percent with non-surgical management.30 Therefore, the primary treatment for these injuries, acute or chronic, usually involves surgical intervention. Surgical repair of these conditions is optimal because of the typical patient demographic and the excellent results surgeons are able to achieve.
In acute injuries, direct repair of the superior peroneal retinaculum is the most common intervention. Eckert and Davis accomplished this with direct suturing of the anterior retinacular edge to the fibrous lip or through direct drill holes in the malleolar ridge if the lip had avulsion for grade I and II injury patterns.27 They reported a 5 percent redislocation rate. Summers and colleagues described a percutaneous technique in traumatic cases, in which surgeons placed Kirschner wires posterior to anterior in the fibula just anterior to the peroneal tendons and allowed indirect repair of the superior peroneal retinaculum.31 They noted no redislocation at follow-up in their series of nine patients. Marti also reported on five patients with primary repair, all of whom were pain-free at 3.5 years.32