[Proximal tibial reconstruction with gastrocnemius flap].

OBJECTIVE: Technique for limb-salvage surgery of tumors of the proximal tibia. Endoprosthetic replacement of the tibia with a modular tumor endoprosthesis and reconstruction of the extensor mechanism with a gastrocnemius flap. INDICATIONS: Primary tumors and recurrences of semimalignant tumors of the proximal tibia. Diagnosis by biopsy and, depending on the entity, neoadjuvant chemotherapy. CONTRAINDICATIONS: Tumor infiltration of nerves or vessels, massive soft tissue infiltration, pathologic fracture, superinfection. SURGICAL TECHNIQUE: The tumor is resected en bloc with wide margins including the biopsy scar, the knee joint is resected intra-extra articular, politeal structures are exposed (anatomical border to the tumor is the popliteus muscle), osteotomy of the tibia 3-5 cm distal of the tumor. After removing the tumor, reconstruction with a modular tumor endoprosthesis is performed. The medial gastrocnemius muscle is detached and mobilized, rotated anteriorly and connected to the patella tendon. Closure of the muscle and skin. POSTOPERATIVE MANAGEMENT: Suction drainage for 48 h, extension brace for 2 weeks, followed by partial weight-bearing for 6 weeks.
RESULTS: Despite technical developments over the years, a complication rate > 10% remains. Secondary amputation due to local recurrence is reported in about 10% of cases and due to infection in 6-12%. Transient or permanent palsy of the peroneal nerve is observed in 5% of cases. A quarter of all patients have full (< 20° extension lag) active extension, the mean extension lag is about 30°. The probability of a revision (including implant related) is 60-70% after 10 years. Based on the clinical results, the technical demanding resection of the proximal tibia is a recommendable procedure.