Analysis of Corrective Distal Tibio-Fibular Osteotomy for Medial Compartment Osteoarthritis and Evaluation of Prognostic Factors: Consecutive 67 Cases in One Center

Abstract

Category: Ankle Arthritis; Ankle; Arthroscopy Introduction/Purpose: A supramalleolar osteotomy is a joint-sparing procedure that can change the mechanical axis load on the ankle joint in the coronal-sagittal planes. Restoration of the axial alignment allows for redistribution of loads to the less affected area of articular cartilage, slowing down or even stopping further articular degeneration. It has been reported that supramalleolar osteotomy has a useful effect in asymmetric varus ankle and medial compartment osteoarthritis, but as far as we know there are not many papers conducted in one center for large cases based study. In our paper, we analyzed the results of multiple cases (67 cases) of supramalleolar osteotomy surgical procedure performed in our center and make insight about prognostic factors like high talar tilt and takakura stage. Methods: From August 2007 to May 2020, a retrospective study was conducted on 67 ankles which underwent distal tibio-fibular osteotomy due to medial compartment osteoarthritis and asymmetric varus ankle in our center. The articular cartilage was evaluated simultaneously with the distal tibio-fibular osteotomy through arthroscopy exam intraoperatively. The mean age was 58.6 years(range 37-73 years). American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, Visual analog scale (Vas) pain score, Range of motion (ROM) and patient satisfaction were used for functional evaluations. Ankle osteoarthritis was classified by Takakura stage, and the tibial anterior surface angle (TAS), tibial lateral surface angle (TLS) and talar tilt angle were measured for radiological evaluations. And, groups were divided according to the Takakura stage, and whether there were significant differences in the measured values was compared. Results: When Preop IIIB and Preop II, IIIA groups were compared, last fu AOFAS score and Pain vas score showed no significant difference. Talar tilt angle showed significant higher value in Preop IIIB group(p<0.05). And TAS angle showed bigger correction in Preop IIIB group with borderline difference. (p=0.07) It seems that overcorrected TAS angle came out to maximize the effect of load transfer to laterally intra-operatively. And it is thought that the overcorrected TAS angle had a good effect on the clinical outcome. When Preop IIIB group were divided stage improved group with not improved group and compared each other, last fu AOFAS score and ROM showed worse results in Postop IIIB group significantly. (p<0.05) Talar tilt showed higher value in Postop IIIB group on preop with borderline differences.(p=0.06) TAS angle showed no significant differences.(p=0.58) Conclusion: We performed SMO for stage IIIB medial ankle OA with significant TAS overcorrection, and achieved favorable clinical outcomes (AOFAS 85.1) when compared with preop stage IIIA group (AOFAS 85.6). Postop stage IIIB group showed higher preop talar tilt angles with poor AOFAS score when compared with postop takakura stage improved group (10.7 and 7.6). Many preop IIIB cases are found to be good candidate for SMO, but skillful selection for SMO is required for good results.