A RARE CASE OF ADULT ACQUIRED FLATFOOT DEFORMITY WITH CHRONIC ATRAUMATIC SUBTALAR DISLOCATION: SUCCESSFUL REDUCTION AND FUSION OF TALONAVICULAR AND TALOCALCANEAL JOINTS

Introduction: We present a rare case of a 65-year-old male patient with adult acquired flatfoot deformity and chronic atraumatic subtalar dislocation due to posterior tibial tendon insufficiency (PTTI).

Aim of the study: The aim of this study is to describe the successful management of this complex case through reduction and fusion of the talonavicular and talocalcaneal joints.

Materials and Methods: A 65-year-old male patient presented with a 7-year history of left foot pain without apparent trauma. Examination revealed tenderness over the talonavicular joint and taut skin overlying the medial foot's talar head. Imaging confirmed lateral displacement of the calcaneus, leading to the diagnosis of lateral subtalar dislocation involving the talonavicular and talocalcaneal joints, secondary to PTTI. The patient underwent surgical intervention comprising reduction and fusion of the talonavicular and talocalcaneal joints. Intraoperatively, residual cartilage was excised, and subchondral bone was curetted. The talus was repositioned and reduced. The talocalcaneal joint was stabilized using three cannulated cancellous screws, while the talonavicular joint was fixed with two bone staples connecting the navicular and talar head. The foot and ankle were immobilized with a splint for 8 weeks.

Results: At the 6-month follow-up, the patient reported no pain during daily activities. Radiographic evaluation demonstrated satisfactory alignment of the talonavicular and talocalcaneal joints, indicative of successful reduction and fusion. The patient experienced improved foot function and mobility.

Conclusion: This case report underscores the successful management of a rare case of adult acquired flatfoot deformity with chronic atraumatic subtalar dislocation resulting from PTTI. Surgical intervention involving reduction and fusion of the talonavicular and talocalcaneal joints yielded favorable outcomes, including pain relief and enhanced functional abilities. The utilization of cannulated cancellous screws and bone staples provided stable fixation and union. Our findings are in accordance to the existing literature, rendering our method as a reasonable treatment.