Extensor Retinaculum Syndrome of the Ankle: An Adult Case Series

Background: Extensor retinaculum syndrome (ERS) is a relatively rarely diagnosed compartment syndrome-like entity caused by elevated pressures in the tissues deep to the superior extensor retinaculum (SER). ERS is identified as out-of-proportion anterior ankle pain, pain with passive toe plantarflexion, elevated SER pressures (>40 mm Hg), and ultimately toe extension weakness and first web space numbness. Although previously described in a pediatric population, this case series is the first to our knowledge in an adult population. Methods: Seven nonconsecutive cases over 18 years from 2 surgeons are reported who underwent complete SER release for ERS either through the direct lateral approach to the fibula or the anterolateral approach to the distal tibia. All were associated with traumatic injuries including 3 bimalleolar ankle fractures, 3 tibial pilon fractures, and 1 distal tibial/fibular shaft fracture. All patients developed writhing anterior ankle pain worsened with passive toe plantarflexion. SER compartment pressures ranged from 50 to >135 mm Hg. Five cases displayed decreased first web space sensation. Results: The diminished or absent first web space sensation uniformly improved post-release. Complications included 1 patient with complex regional pain syndrome type 1, 1 patient required hardware removal, and 2 had persistent but improved first web space sensation changes. Conclusion: Clinical suspicion for possible ERS should arise after distal tibial/fibular fractures when the excruciating pain localizes to the ankle instead of the classic anterior leg muscle bellies. If pain is worsened with passive toe plantarflexion, this diagnosis should be considered. Recommended treatment involves complete release of the SER anywhere on the anterior surface between the tibia and fibula depending on the approach needed for fixation of the associated fracture. Level of Evidence: Level IV, case series.