Both the medial and lateral gastrocnemius muscles may be used independently or in conjunction with each other. The medial gastrocnemius will cover the inferior thigh, knee, and proximal tibia. The medial head of the muscle is used most frequently as a proximally based flap due to its larger size in comparison to the lateral head of the muscle. The lateral head may also be used alone or in combination with the medial head for coverage of large tibial defects or for lateral distal thigh wounds. For defects at the level of the mid-portion of the tibia, the gastrocnemius muscle may not provide adequate coverage and the soleus muscle is preferred for coverage of middle third defects. For defects involving the distal third of the tibia and ankle, free tissue transfer is usually required. The tendinous inferior margin of the gastrocnemius muscle may be used to augment the repair of an injured suprapatellar tendon.

Contraindications to the use of the gastrocnemius muscle flap include active infection and/or significant disruption of the soft tissue and/or vascular pedicle. Additional contraindications for flap use include any procedure or injury which may have traumatized or injured the sural artery, such as a previous repair of a popliteal arterial laceration or repair of popliteal aneurysm. Occasionally, severe compartment syndromes may render the muscle fibriotic and useable for transfer, but due to its superficial location and high take off of the sural artery, this is unusual. Direct trauma to the posterior calf may result in muscle destruction and should be ruled out prior to proceeding with flap elevation. Radiation to the knee following tumor extirpation may also compromise the vascular pedicle,
increasing the chance of total or partial muscle necrosis following transfer. The muscle should not be used if the soleus and contralateral gastrocnemius muscle are no longer functional, as this will create postoperative difficulty with plantar flexion. A history of a recent deep venous thrombosis within the involved extremity is a relative contraindication for the use of the flap, although we have used the flap successfully in such situations.

Distally based gastrocnemius muscle flaps have been described for coverage of middle third and lower leg defects. Vascular supply to the muscle in these cases is supplied through crossing anastomotic arterial connections between the medial and lateral gastrocnemius muscle bellies extending across the midline raphe. Use of the flap in this manner is not common, as more reliable methods of middle third and lower leg coverage are available and include the soleus muscle flap, the sural artery flap, and free flap coverage.

The preoperative management of severe open fractures involves stabilization of the patient, tetanus prophylaxis, and broad-spectrum antibiotics. Trauma often compromises the availability of the skin and soft tissue surrounding the knee. Nonviable tissue requires aggressive debridement. Serial debridements may be needed if tissue viability is uncertain. Once the wound bed is clean, flap coverage may proceed, ideally within 72 to 96 hours following initial injury. Preoperative physical examination should focus on determining the function of the remaining muscles of the lower leg to determine if sacrifice of the gastrocnemius could result in a significant loss of plantar flexor following muscle transfer. A vascular examination should also be performed to assess for the patency of the popliteal artery. In those patients with a history of peripheral vascular disease or a history of popliteal arterial trauma, an angiogram can confirm patency of the sural artery prior to surgery.