Background: Supramalleolar osteotomy (SMO), which redistributes the load line within the ankle joint, has been reported as an effective treatment for varus ankle osteoarthritis. However, no study has examined cartilage regeneration in the medial compartment of the ankle after SMO.

Hypothesis/Purpose: This study aimed to investigate the clinical and radiological outcomes of SMO and to identify the association between the outcomes of SMO and cartilage regeneration evaluated by second-look arthroscopy. The hypothesis was that cartilage regeneration would be an important predictor of the outcomes of SMO and that arthroscopic marrow stimulation would aid in cartilage regeneration.

Study Design: Case series; Level of evidence, 4.

Methods: A total of 31 ankles were retrospectively evaluated after arthroscopic marrow stimulation with SMO for varus ankle osteoarthritis; second-look arthroscopy was conducted for all these ankles. Clinical outcome measures included a visual analog scale (VAS) for pain and the American Orthopaedic Foot and Ankle Society (AOFAS) score. Radiological outcome variables included the tibial-ankle surface angle (TAS), talar tilt (TT), and tibial-lateral surface angle (TLS), and progression of degenerative arthritis of the ankle was assessed. In the second-look arthroscopy, cartilage regeneration was evaluated using the International Cartilage Repair Society (ICRS) grade.

Results: The mean ± standard deviation VAS and AOFAS scores were 7.1 ± 0.8 and 62.9 ± 4.0 preoperatively, and they significantly improved to 3.4 ± 1.3 and 83.1 ± 7.5, respectively (P < .001, for both) at the time of the second-look arthroscopy (mean, 13.2 months postoperatively). However, at final follow-up (mean, 27.4 months postoperatively), they were significantly decreased to 4.1 ± 1.6 and 79.9 ± 8.0, respectively, compared with the values at second-look arthroscopy (P < .001, for both). The mean TAS, TT, and TLS improved significantly after SMO but showed no significant correlation with the clinical outcomes and ICRS grade (P > .05 for all three). At second-look arthroscopy, the ICRS overall repair grades were normal in 1 (3%), nearly normal in 7 (23%), abnormal in 13 (42%), and severely abnormal in 10 (32%). Progressive degenerative arthritis was observed in 13 cases (42%). The ICRS grade was significantly associated with the clinical outcomes (P < .0001) and development of degenerative arthritis of the ankle joint (P = .002).

Conclusion: This study showed improved clinical outcomes after SMO for varus ankle osteoarthritis in comparison to the preoperative assessments. Furthermore, the ICRS grade was significantly associated with the clinical outcomes of SMO at final follow-up and significantly associated with the development of degenerative arthritis of the ankle joint. Therefore, arthroscopic marrow stimulation should be considered with SMO to ensure adequate cartilage regeneration. However, given the ICRS grades observed at the time of the second-look arthroscopies and the progression of degenerative arthritis in 42%, the long-term prognosis in this group of patients is uncertain.