[Reconstruction of the medial collateral ligament complex with a flat semitendinosus auto- or allograft].

Objective: Replacement of superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL) with an allograft.

Indications: Chronic 3° isolated medial instability and combined anteromedial or posteromedial instability.

Contraindications: Infection, open growth plates, restricted range of motion (less than E/F 0-0-90°).

Surgical technique: Longitudinal incision from medial epicondyle to superficial pes anserinus and exposure of the medial collateral ligament complex. Thawing of the allogeneic semitendinosus tendon graft at room temperature, reinforcement of the tendon ends with sutures and preparation of a two-stranded graft. Placement of guidewires in the sMCL and POL insertions and control with image intensifier. Tunnel drilling. Pulling the graft loop into the femoral bone tunnel and fixation with a flip button. Pulling the two graft ends into the tibial tunnels. Tibial fixation by knotting the suture ends in a 20° flexion on the lateral cortex. Suture the tendon bundles to the remaining remnants of the medial collateral ligament complex to adopt the flat structure of the natural medial collateral ligament complex.

Postoperative management: Six weeks partial weight-bearing, immediately postoperatively splint in the extended position, after 2 weeks movable knee brace for another 4-6 weeks. Mobility: 4 weeks 0-0-60, 5th and 6th weeks 0-0-90.

Results: From 2015-2021, this surgical procedure was performed in 19 patients (5 women, 14 men, age 34 years). Mean Lysholm score at follow-up after at least 2 years was 89 (76-99) points. In 6 patients, there was restricted range of motion 3 months postoperatively, which resulted in further therapy (3 × systemic cortisone therapy, 3 × arthroscopically supported manipulations under anesthesia).