Purpose: To examine the association between thigh muscle strength 4 years after partial meniscectomy due to a medial non-traumatic tear, with radiographic features of osteoarthritis 15 years after the meniscectomy. Methods: 34/45 subjects (11 women) with mean age 57 (range 50-61) years, who participated in an exercise trial post-meniscectomy and underwent baseline testing for isokinetic thigh muscle strength 4 years after surgery, came back for radiographic examination 15 years after surgery. Endpoints were grade of joint space narrowing (JSN) and osteophyte (OF) score in the medial tibiofemoral compartment (MTFC) of the index knee and the contralateral knee. Radiographs were read by two observers separately, blinded to the exposure status and consensus reached by adjudication. We tested the association between muscle strength and the radiographic OA features using linear regression analyses adjusted for age, sex and body mass index (BMI). Results: At baseline (pre-exercise) mean age was 46 years, mean BMI was 26.0, mean knee extensor and flexor strength deficit in the index leg were 11% and 3%, respectively. At the 15 year follow-up, all subjects but one had joint space narrowing (JSN) in the MTFC of the index knee, and 23/34 subjects had JSN in the MTFC of the contralateral knee. 27/34 subjects had osteophytes (OF) in the MTFC of the index knee and 22/34 subjects had OF in the MTFC of the contralateral knee. In the index knee we found a negative association between baseline knee extensor and knee flexor strength and grade of JSN at follow-up both in the crude and adjusted model (R 2 ¼0.43 and 0.40, p¼0.014 and 0.028, respectively, adjusted model). Further, in the index knee, knee extensor and knee flexor strength were inversely associated with OF score (R 2 ¼ 0.40 and 0.38, p¼ 0.013 and 0.021, respectively, adjusted model).In the contralateral knee, the association between baseline knee extensor and knee flexor strength and JSN grade at follow-up was weak and nonsignificant (R 2 ¼ 0.25 and 0.24, p¼ 0.48 and 0.61, respectively, adjusted model). However, we found a tendency to a negative association between knee extensor strength and OF score (R 2 ¼ 0.46, p¼0.057, adjusted model) but no significant association between knee flexor strength and OF score (R 2 ¼0.45, p¼0.093, adjusted model). Conclusions: Better thigh muscle strength 4 years after surgery was associated with less OA changes in the meniscectomized knee but not in the contralateral knee 11 years later. Our findings indicate that good thigh muscle strength may reduce the risk of radiographic knee OA development after meniscectomy due to a non-traumatic tear.