Background: Realignment-surgery to unload ankle osteoarthritis (OA) has been proposed as treatment alternative for varus and valgus ankle OA. Sports activity after this procedure has not been analyzed. Realignment-surgery increases sports activity. Sports activity correlates with ankle pain, function, and alignment, but does not influence revision rate. Materials and Methods: Prospective case series of 35 consecutive patients with post-traumatic varus or valgus ankle OA limited to half tibiotalar joint surface were treated by OA unloading realignment-surgery. Distal tibia osteotomy was used in all cases; additional osteotomies, tendon, ligament procedures in 92% of cases. Main Outcome Measurements: Pain (visual-analogue-scale; VAS), ankle range-of-motion (ROM); function (American-Orthopaedic-Foot-and-Ankle-Society (AOFAS) ankle-score; Swiss-symptom-related-Ankle-Activity-Scale (SAAS); Sports-Frequency-Score (SFS), OA and tibiotalar-alignment-grade (Takakura-Score), and revision surgery. Mean followup was 5 years. Results: Mean values from preoperative to followup: VAS decreased (p = 0.0001) 4 points; ankle ROM increased (p = 0.001) 5 degrees; AOFAS-Score increased (p = 0.0001) 46 points; SAAS increased (p = 0.0001) 42 points; SFS increased (p = 0.02) 0.5 grades; Takakura-score decreased (p = 0.0001) 1.0 grades. Revision surgery was performed in 10 cases (29%). Three of these were revised to ankle arthroplasty. At followup, SAAS correlated with VAS, AOFAS score, Takakura score, and not with ROM or SFS. SFS did not correlate with other variables. Patients needing revision surgery had a higher (p = 0.003) SFS than patients who needed no revision. Conclusion: Realignment-surgery increased sports activity of ankle OA patients. Improved ankle pain and function correlated with ability to perform activity without symptoms; however, sports frequency had no correlation to patients' ymptoms but showed higher revision rate.