BACKGROUND: Few studies reported the long-term clinical outcomes and joint degeneration of patients with chronic lateral ankle instability (CLAI) and small osteochondral lesions of the talus (OLTs) following simultaneous open modified Broström-Gould (MBG) surgery and arthroscopic bone marrow stimulation (BMS). The purpose of this study was to study the long-term results of patients after BMS and BMG surgery, and to further evaluate the potential effect of OLT size on postoperative results. METHODS: In this retrospective study, 110 CLAI patients were divided into 57 patients with OLTs (including 24 patients having combined small osteochondral lesions of the tibial plafond) receiving simultaneous BMS and MBG surgeries (BMS+MBG group), and 53 patients without OLTs receiving isolated open MBG surgery (MBG group). The OLT size and pre- and postoperative Kellgren-Lawrence grade were assessed. The subjective scores (visual analog scale pain score, Tegner activity, and Karlsson-Peterson scores), surgical complications, and return to sports were also compared pre- and postoperatively. RESULTS: Patients were followed up at a mean of 144.2 ± 14.9 and 145.6 ± 11.4 months for the BMS+MBG and MBG groups, respectively. Subjective scores were significantly improved ( CONCLUSION: Patients with CLAI and small OLTs following simultaneous open MBG surgery and arthroscopic BMS showed good long-term outcomes and only mild progression of joint degeneration-overall similar to patients treated for CLAI with MBG surgery. Moreover, as OLT size increased, good outcomes were less predictable.