The role of the gastrocnemius muscle flap in limb-sparing surgery for bone sarcomas of the distal femur: A proposed classification of muscle transfers

Limb-sparing surgery for bone and soft-tissue sarcomas involves three phases: (1) resection of the tumor with free margins, (2) reconstruction of the bone and joint defect, and (3) reconstruction of the soft tissues. This presentation focuses on the third phase. Between January of 1988 and January of 1994 we performed 33 distal femoral resections, 32 for malignant and 1 for benign tumors. There were 19 men and 14 women aged from 6 to 78 years (mean age 28 years). Twenty-seven patients had gastrocnemius muscle flap transfers, 24 having 'primary' transfers and 3 having 'secondary' transfers. The lateral gastrocnemius muscle was used in 18 patients, the medial in 8 patients, and both in 1 patient. We propose a classification of the transfers based on the size of the soft-tissue defect above the prosthesis needing coverage and the length of the neurovascular bundle of the muscle. Twenty-six of the 27 muscles survived; one patient had necrosis of the skin and muscle. Two patients had persistent sinuses at the scar that were managed successfully (one of them was before a secondary muscle transfer). Six patients did not have gastrocnemius muscle flap transfers. Two of them had persistent sinuses for years, and one patient had titanium 'synovitis' and needed repeated operations including removal of the prosthesis and revision. The particular vascularization of the gastrocnemius muscle (one pedicle at the level of the knee joint) situated close to its origin, the size of the muscle belly, and the fact that it is situated in the dissection field and its transfer does not affect the function of the spared limb make it particularly suitable for the coverage of the wide areas of skin and muscle loss at the knee region. In the classification that we propose, type I is reversed for coverage of small areas, while types II and III are used for coverage of larger areas. Flap transfer should be performed primarily at the time of the resection in order to avoid complications of wound healing and to reduce delays in chemotherapy protocols.