[Tumour-related extra-articular knee joint resection]

Wide 'en bloc' extra-articular resection of the knee joint while maintaining the necessary safety margins for adequate oncological therapy and reconstruction using a knee joint endoprosthesis with the aim of preserving good extensibility of the knee joint.

Infiltration of the knee joint by soft tissue or bone sarcomas, pathological intra-articular fractures, (potential) contamination of the knee joint due to inappropriate biopsy approach.

Advanced tumour manifestation with no possibility of wide tumour resection with preservation of the extremity, progressive multiple metastatic tumour disease with a short prognosis, florid infections.

Lateral approach, circular incision of the biopsy approach, patella osteotomy in the frontal plane with prior K‑wire marking, careful separation of the retinaculum from the fascia, osteotomy of the distal femur corresponding preoperative planning, distal separation of the gastrocnemius origins for dorsal capsular reconstruction, flexion of the knee joint for better medial separation of the retinaculum from the fascia, marking of the proximal osteotomy of the tibia proximal to the tibial tuberosity to protect the patellar tendon, reconstruction using a modular tumour endoprosthesis after tumour resection.

Axial 20 kg partial weight-bearing for 6 weeks postoperatively in an extension brace and then gradually increasing flexion 30° every 2 weeks in a flexion-limiting knee joint brace. Oncological therapy and aftercare as determined by the tumour board.