Using double-bundle Achilles tendon–bone allograft for reconstruction of compound loss of lateral malleolus and lateral ankle ligaments: A rare case report

RATIONALE: Composite defects of the lateral ankle, involving bone loss, ligament disruption, and soft tissue compromise, cause profound mechanical instability and are difficult to reconstruct with techniques that address bone or ligaments alone. PATIENT CONCERNS: We report a 26-year-old woman who presented with progressive right ankle pain, recurrent giving-way, and peroneal tendon subluxation 7 years after a high-energy crush injury that required flap coverage. DIAGNOSES: Lateral malleolar loss with a distal fibular bony defect measuring approximately 5 × 3 × 2 cm and chronic varus instability; complete anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) rupture; and peroneal tendon dislocation were confirmed by stress radiographs and magnetic resonance imaging. INTERVENTIONS: Single-stage reconstruction with a cryopreserved Achilles tendon-bone allograft. The calcaneal bone block was contoured and fixed to the fibular stump with a 4.5-mm cannulated screw to reconstitute the lateral malleolus. The tendon was split into 2 bundles (7 mm × 30 mm for the ATFL and 7 mm × 40 mm for the CFL) for anatomic ATFL and CFL reconstruction and secured with interference screws at the talar and calcaneal footprints. The peroneal tendons were reduced after bony restoration. Postoperative rehabilitation used an Aircast® brace with non-weight-bearing ambulation for the first 3 weeks, partial weight-bearing from week 3, full weight-bearing by week 6, and brace discontinuation at week 12. OUTCOMES: At the final follow-up of 16 months, the patient ambulated pain-free with a stable ankle. Radiographs demonstrated successful incorporation of the bone allograft, and magnetic resonance imaging confirmed intact ATFL/CFL grafts with maintained peroneal tendon reduction. Functional scores were Karlsson-Peterson 87 and American Orthopaedic Foot & Ankle Society ankle-hindfoot 90. LESSONS: A double-bundle Achilles tendon-bone allograft enables simultaneous reconstruction of lateral malleolar bone and lateral ligaments, avoiding donor-site morbidity and achieving durable stability in complex, previously reconstructed ankles. This approach should be considered when both osseous and ligamentous deficits coexist.