Novel Minimally Invasive Sliding Calcaneal Osteotomy: A Case Series

CATEGORY: Hindfoot; Ankle INTRODUCTION/PURPOSE: Sliding calcaneal displacement osteotomy is a mainstay in the treatment of hindfoot deformity. A lateral oblique or L shaped incision and direct visualization of the calcaneus is the traditional open approach to this osteotomy. Complications of this approach are not common and include wound dehiscence, delayed union, neurovascular damage, tarsal tunnel syndrome, symptomatic bony overhang and peroneal fibrosis. Several techniques have been developed to address the limitations of the open approach including osteotomy with a Gigli saw, percutaneous endoscopic assisted osteotomy, and most recently minimally invasive osteotomy (MICO) with a low speed, high torque burr. Each of these techniques has limitations. This report presents a simple minimally invasive technique that may help mitigate wound issues without the technical hurdles of a steep learning curve. METHODS: Patients undergoing MICO procedures with the senior author from February 2019 - June 2020 who had not undergone previous foot/ankle surgery were retrospectively enrolled. Patients underwent clinical and radiographic assessment preoperatively as well as at 2, 6, 12, and 24 weeks postoperatively. The technique utilizes a 1.5cm incision along the plane of osteotomy, centered about a K-wire placed through both cortices of the calcaneus at the midpoint of the osteotomy plane. The plane and K-wire placement are determined under radiographic guidance. A micro-sagittal saw is rested on the K-wire and used as a cutting block in the coronal plane. After the osteotomy is created and mobility of the calcaneus confirmed, the K-wire is removed. The mobile segment is adjusted as needed, held in placed by dorsiflexing the ankle, and fixed using two posterior-to-anterior 6.5 cannulated screws, one 1cm superior to the other. The wounds can then be irrigated and closed. RESULTS: 37 patients were treated using this technique. 24 (65%) patients were female, with average age 56.9 years. Osteotomies were performed concomitantly with procedures including flexor digitorum longus transfer, subtalar fusion, triple arthrodesis, talonavicular fusion, hallux valgus corrective osteotomy, and Strayer gastrocnemius recession. Thirty-five (95%) patients achieved radiographic fusion within 1 year postoperatively with 28 (76%) fusing by 3-month follow up. Two (5%) patients developed a radiographic non-union without instability and opted to be managed expectantly. Of note, one patient is a diabetic current smoker with Rheumatoid Arthritis, while the other is a non-diabetic former smoker. A single patient was readmitted within 90 days for incision and debridement of a dehisced wound from subtalar fusion performed concomitantly. One patient underwent eventual removal of the screw compressing the calcaneal osteotomy site due to hardware prominence. No patients reported peroneal symptoms postoperatively. No patients reported any other complications related to the osteotomy. CONCLUSION: Sliding calcaneal displacement osteotomy is a well-established component in the treatment of hindfoot deformity. Although larger lateral oblique and L shaped incisions allow direct visualization of the osteotomy, more minimally invasive approaches have been used. The proposed technique in the current report offers a low non-union rate, minimal surgical footprint, easily available surgical instruments, reliable osteotomy plane, and short surgical time.