Objective <p>Lengthening of the patellar tendon to normalize patellar height and improve knee flexion deficits.</p> Indications <p>Flexion deficits in combination with patella baja (Caton index &lt; 0.6).</p> Contraindications <p>Infection.</p> Surgical technique <p>Arthroscopy of the knee and resection of adhesions in suprapatellar pouch and additional intraarticular adhesions. Approximately 15 cm long incision from tibial tuberosity up to the patella. Exposition of the patellar tendon. Longitudinal incision in the middle from the tibial tuberosity towards the proximal patella. Division of the tendon into two strands. Detachment of the lateral tendon strand with periosteum from the bone of the patella and detachment of the medial strand with periosteum from the bone of the tibial tuberosity. Resection of fibrotic adhesions within Hoffa’s fad pad and detachment of the longitudinal retinacula. Lengthening of the patella tendon of maximal 2.5 cm. Refixation of the medial strand to the upper part of the tibial tuberosity and the lateral strand to the distal patella pole with a&#xa0;soft anchor. Drilling of small transverse bone tunnels in the patella and tibial tuberosity for application of a&#xa0;McLaughlin cerclage for augmentation of the z‑plasty with a&#xa0;thick braided suture cord.</p> Postoperative management <p>Six weeks partial weight bearing with 10 kg within a&#xa0;straight leg brace. Free passive range of motion.</p> Results <p>Previously published results show that the Z‑plasty technique presented here on the patellar tendon can normalize the Caton index and improve mobility and clinical scores.</p>