ObjectiveTo evaluate the effectiveness of semitendinous and gracilis transfer for the treatment of medial collateral ligament (MCL) injury caused by total knee arthroplasty (TKA). MethodsBetween March 2009 and May 2014, 11 patients (11 knees) with MCL injuries caused by primary TKA were treated by semitendinous and gracilis transfer in primary TKA (injury group). Another 18 patients (21 knees) without MCL injury were included as the control group. There was no significant difference in gender, age, injury sides, disease duration, body mass index, knee varus deformity, and preoperative Knee Society Score (KSS) between 2 groups (P>0.05), with comparability. KSS score was used to evaluate the function after operation. ResultsPrimary healing of incision was obtained in all patients, and no complications of joint instability and pain occurred. The follow-up time was 6-29 months in injury group and was 7-34 months in control group. At last follow-up, the KSS clinical score and functional score were significantly increased to 89.82±3.76 and 89.54±3.50 in the injury group (P<0.05) and were significantly increased to 90.19±3.39 and 90.00±3.53 in the control group (P<0.05) respectively, but no significant difference was shown between 2 groups (t=0.158, P=0.877; t=0.820, P=0.432). X-ray films showed no prosthetic loosening or subsidence during follow-up. ConclusionThe semitendinous and gracilis transfer is reliable for the treatment of MCL injury caused by TKA. The insertions of semitendinous tendon and gracilis are close to that of the knee MCL, which can effectively improve knee function.