Pedicled gastrocnemius flap: clinical application in limb sparing surgical resection of sarcoma around the knee region and popliteal fossa.

OBJECTIVE: To highlight on the versatility of superiorly based pedicled gastrocnemius muscle flap in the limb-sparing surgery for bone or soft tissue sarcoma around the knee and popliteal fossa.

PATIENTS AND METHODS: A total of 30 patients with localized bone or soft tissue sarcoma around the knee and popliteal fossa were treated with limb-salvage procedure. The study included 5 cases with bone sarcoma of the distal femur, 15 cases having bone sarcoma of proximal tibia and 10 cases having soft tissue sarcoma around the knee region and popliteal fossa. Routine preoperative staging studies were done for every patient and included local plain radiography, local MRI, isotopic bone scan and CT chest. Local MRA or angiography was done in selected cases. According to the Enneking staging system, 19 patients had stage IIB and 11 had stage IIA. Patients having bone sarcoma of the proximal tibia were subjected to wide resection, endoprosthetic reconstruction and reconstruction of the extensor mechanism by the medial gastrocnemius muscle flap. Patients having bone sarcoma of the distal femur were subjected to wide resection, endo prosthetic reconstruction and coverage of the prosthesis and rebalance of the patellar tendon by the medial gastrocnemius flap. Patients having soft tissue sarcoma were subjected to wide resection and soft tissue coverage with either medial or lateral myocutaneous gastrocnemius flap or muscle flap with grafting. Limb function was evaluated according to MSTS functional scores. Adjuvant chemotherapy or radiotherapy was given according to nationally-agreed protocols.

RESULTS: There were 18 males and 12 females with a mean age of 29 years at the time of surgery (range 11-44 years). The mean follow-up period was 52 months (range 25-72 months). Resection with a negative bony and soft tissue margins could be achieved in all cases. A total of 30 flaps were used and included medial gastrocnemius muscle flaps in 21 cases (15 cases had proximal tibia endoprothesis, 5 cases had distal femur endoprothesis, 2 cases had soft tissue sarcoma infiltrating the chin of tibia), myocutaneous gastrocnemius flaps in 8 cases having soft tissue sarcoma (5 had medial head flap and 3 cases lateral head flap). Flap survival was 100&. The success rate of limb salvage was 96.6% with high score functional results according to MSTS functional scores. The area of the skin island harvested in cases of myocutaneous flaps ranged from 11 to 18cm in length and from 5 to 8cm in width and all these cases required grafting of the donor site. Complications included partial wound dehiscence in one case, revision of the prosthesis in one case, amputation due to local recurrence in one case and significant extension lag in 2 cases.

CONCLUSION: The unique vascularization of the gastrocnemius muscle (one pedicle to each head), the size of the muscle belly, the fact that it is situated in the dissection field and that its transfer does not affect the function of the spared limb too adversely, makes it particularly suitable for limb sparing procedures for sarcoma in the region of the knee and popliteal fossa. The medial head is the workhorse muscle flap for soft tissue coverage of knee endoprothesis and reconstruction of extensor mechanism. This decreases the rate of complications and improves the functional outcome. Reconstruction of the soft issue defect improves wound healing, protects exposed deep structures and subsequently prevents wound problems, delays adjuvant therapy and secondary amputation.