Bimalleolar equivalent fractures: should the medial approach be systematic?

Bimalleolar equivalent fractures combine a suprasyndesmotic lateral malleolar fracture with a deltoid ligament (DL) lesion, which often goes unnoticed. Failure to recognise such lesions may lead to an irreducible ankle due to tibialis posterior tendon interposition, as well as medial instability and long-term arthrosis. The diagnostic and therapeutic management of the DL remains controversial. The aim of this study was to clarify the features of this lesion, review diagnostic modalities, and propose an approach to surgical management of the DL.

Methods: Twenty-three patients with a bimalleolar equivalent fracture were treated surgically between January 2018 and December 2024 in the Orthopaedic Traumatology Department of the Ibn Rochd University Hospital Centre in Casablanca. The mean age was 24.1 years (range 21 to 47), with a sex ratio of 2.83. All patients underwent a systematic primary medial approach for exploration and repair of the medial ligamentous structures. A dynamic valgus stress test under fluoroscopy was performed in patients with a preoperative medial clear space (MCS) greater than 5 mm. Outcomes were assessed using the EFAS score and a visual analogue scale for pain.

Results: DL lesions were identified in 13 patients (56.5%), including 11 complete ruptures and two strains. Incarceration of the tibialis posterior tendon was noted in three cases. All ruptures were associated with medial ecchymosis. After lateral osteosynthesis, DL repair was performed using resorbable sutures. At a mean follow-up of 3.1 years, ankle function was rated very good in 78.2% of patients, with a mean VAS of 1.5. Two patients developed medial impingement syndrome, but no medial instability was observed.

Conclusion: A systematic medial approach is not warranted in all bimalleolar equivalent fractures, but remains mandatory when clinical signs (medial ecchymosis, oedema) and radiological findings (MCS greater than 5 mm, with or without stress test) suggest DL injury. Early repair prevents medial instability and long-term arthrosis.