BACKGROUND

 

 

Malignant tumors of the soleus and gastrocnemius muscles are rare and have been traditionally treated with above-knee amputation. During the past 20 years, the treatment of soft tissue sarcoma of the lower extremities has undergone a dramatic shift toward limb salvage procedures.

 

Better understanding of the biologic behavior of these tumors, the availability of effective neoadjuvant chemotherapy (which often decreases the tumor size and facilitates a more conservative resection), and the recognition that close negative surgical margins in conjunction with postoperative radiation therapy often provide good local control, thus allowing tumor resection instead of amputation in most cases.

 

ANATOMY

 

The soleus and gastrocnemius muscles form a tripartite muscle sometimes referred to as the triceps surae muscle. Together with the plantaris muscle, they form the superficial posterior muscle group of the leg. These muscles act together in plantarflexing the foot and ankle joint.

 

The gastrocnemius muscle is the most superficial in the superficial posterior compartment and forms most of the prominence of the calf. It has two heads of origin. Its medial head is slightly larger and extends a little more distal than its lateral head. The two heads converge at the inferior margins of the popliteal fossa where they form the inferolateral and inferomedial boundaries. The lateral head originates from the lateral surface of the lateral femoral condyle and the medial head arises from the popliteal surface of the femur, superior to the medial condyle.

 

The soleus muscle is a broad, fleshy muscle that lies deep to the gastrocnemius muscle. It arises from the posterior aspect of the head and superior fourth of the fibula, the soleal line, and the middle third of the medial border of the tibia. It also arises from the tendinous arch between the tibia and fibula, which arches over the tibial vessels. The soleus muscle and both heads of the gastrocnemius converge to form the Achilles tendon, which inserts into the posterior surface of the calcaneus.

 

INDICATIONS

Tumors that arise from and are completely within the soleus muscle Most low-grade and some high-grade sarcomas

 

 

IMAGING AND OTHER STAGING STUDIES

Computed Tomography and Magnetic Resonance Imaging

 

Careful examination of the computed tomography (CT) and magnetic resonance imaging (MRI) is essential in determining resectability. Tumors that extend to and around the popliteal trifurcation or into the gastrocnemius

muscles usually require an amputation (FIG 1).

 

The popliteal space must also be evaluated. Proximal tumors arising within the soleus muscle often extend into the popliteal space and may involve the popliteal vessels, the sciatic nerve, or both.

 

Bone Scanning

 

Bone scans may show involvement of the adjacent tibia, fibula, or both.

 

Areas of uptake should lead to close examination of the corresponding cuts of the MRI and CT scans.

 

Angiography and Other Studies

 

Biplane angiography is very useful in determining vascular displacement or encasement.

 

Careful analysis of the popliteal trifurcation is necessary before surgery and may indicate tumor involvement and thus the need for an amputation.

 

Biopsy

 

The biopsy site should be in line with the planned incision for resection and must be located over the most prominent portion of the tumor.

 

Core needle biopsy has been shown to provide reliable pathologic diagnoses and is our preferred method. Multiple samples can be collected from the same puncture site.

 

Areas where major arteries and veins traverse should be avoided so as not to penetrate the vessels and risk tumor cell contamination.

 

SURGICAL MANAGEMENT

 

Care must be taken to identify, mobilize, and protect critical structures in the posterior leg.

 

Positioning

 

Resection is performed with the patient in a prone position. General or epidural anesthesia is used.

 

 

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FIG 1 • This patient with an alveolar soft part sarcoma of the soleus muscle was treated with induction chemotherapy followed by limb salvage surgical resection and reconstruction with a Gore-Tex vascular graft. A,B. The axial and coronal T2-weighted MRIs show a large tumor arising within the soleus muscle. Arrows show the extension of the tumor. C. T2-weighted MRI demonstrating a tumor arising from the soleus and encroaching on both the posterior tibial artery and the peroneal artery. Both vessels appear patent at this point in time, although an angiogram may be useful for surgical planning. D. Three-dimensional (3-D) CT angiogram is useful to determine the local compartmental anatomy and the proximity of the soleus tumor to the peroneal vessels and the posterior tibial artery and will demonstrate any vascular anomalies within the planned surgical field.

 

TECHNIQUES

• Resection of Soleus Muscle with or without Adjacent Gastrocnemius Muscle

The initial incision is made longitudinally on the posterior aspect of the leg and shifted medially or laterally, depending on the anatomic location of tumor (TECH FIG 1). A lateral incision is used if resection of the lateral gastrocnemius is planned. A midline posterior incision is used for resections of the medial gastrocnemius, soleus, and deep posterior compartment.

 

 

The fascia is dissected with the subcutaneous tissues, and large fasciocutaneous flaps are raised. The peroneal nerve is first identified and placed within a vessel loop; this is followed by careful dissection to identify the sciatic and tibial nerves.

 

The popliteal vessels are identified by opening up the deep fascia overlying the two heads of the gastrocnemius. Radical excision of the medial or lateral heads of the gastrocnemius is achieved by ligation of their main pedicle (medial or lateral sural artery and vein, respectively) and transection of their femoral origin and insertion to the Achilles tendon.

 

Exposure for resection of the soleus muscle is achieved by partial or complete Achilles tenotomy and reflection of the medial and lateral heads of the gastrocnemius muscle proximally.

 

By blunt dissection, the soleus is separated from the transverse intermuscular septum, which outlines the deep posterior compartment. The soleus can then be detached from its tibial and fibular origins and calcaneal insertion.

 

Residual defects in the Achilles tendon should be reconstructed. The wound is then closed over closed suction drains.

 

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TECH FIG 1 • A. Anatomy and a utilitarian approach to the posterior compartment of the leg. B. Clinical photograph demonstrating the planned surgical midline incision and location where the medial and lateral heads of the gastrocnemius will be released. C. Exposure of the tumor and identification of the posterior vessels requires the release of the medial and lateral heads of the gastrocnemius muscle from the Achilles tendon. D. Following incision and creation of fasciocutaneous flaps, the identification and mobilization of critical anatomic structures of the posterior leg occurs. E. The medial and lateral heads of the gastrocnemius have been mobilized. F. Once the medial gastrocnemius is elevated, the soleus muscle is visualized and tumor resection can occur. (continued)

 

 

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TECH FIG 1 • (continued) G. The massive defect created by wide resection of a soleus muscle sarcoma or carcinoma. H. Following tumor resection, a portion of the lateral soleus was retained in this case. The peroneal artery and vein, posterior tibial artery and vein, and the posterior tibial nerve all remain intact.

• Functional Reconstruction after Resection

 

Functional reconstruction is usually necessary after resection of soleus tumors because of the complete resection of the proximal part of the Achilles tendon. It consists of tenodesing the medial and lateral heads of the gastrocnemius muscle and incorporating them with a Gore-Tex vascular graft. The length of the vascular graft depends on the size of the tumor and the gap between the resected stump and the Achilles tendon.

 

The Gore-Tex vascular graft is sutured to the stump of the Achilles tendon with a 3-mm Dacron tape and no. 0 Ethibond sutures (TECH FIG 2A-D).

 

 

 

TECH FIG 2 • A. The Gore-Tex vascular graft was sutured to the stump of Achilles tendon. Inset shows a close-up of the graft stump junction. B. Suturing the medial and lateral heads of the gastrocnemius muscle and their incorporation with the Gore-Tex vascular graft. C. This intraoperative photograph shows the anatomic defect reconstructed with the Gore-Tex vascular graft (arrows), which was anastomosed to the remaining gastrocnemius muscle (MG, LG) and the stump of the Achilles tendon (AT) with no. 0

Ethibond and 3-mm Dacron tape. (continued)

 

 

 

TECH FIG 2 • (continued) D. Postoperative MRI shows the Gore-Tex graft extending from the insertion of gastrocnemius muscle to the remaining stump of the Achilles tendon. E. After tumor resection, the surgical specimen consists of the biopsy tract (BX), the tumor, and the entire soleus muscle belly (arrow).

 

 

The retracted gastrocnemius and soleus muscle stump is pulled out and sewn with the Gore-Tex aortic graft under moderate tension with a 3-mm Dacron tape and no. 0 Ethibond sutures.

 

After resection of the tumor, the surgical specimen consists of the biopsy tract, the tumor, and the entire soleus muscle belly (TECH FIG 2E).

 

The foot is kept in the neutral position during these reconstructive procedures. A posterior splint is used to maintain the foot in neutral position and the knee in 15 degrees of flexion.

 

 

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PEARLS AND PITFALLS

Preoperative ▪ Large tumors of the soleus muscle may extend further than anticipated.

• Preoperative evaluation of the popliteal space and vessels is mandatory.

   

  Intraoperative ▪ Reconstruction with a Gore-Tex graft after resection is recommended for large soleus defects.

• The surgeon should carefully mobilize the popliteal vessels before attempting to resect the tumor. An intraoperative Doppler scan may be useful.

 

 

POSTOPERATIVE CARE AND REHABILITATION

 

Postoperatively, the leg is immobilized in a long-leg splint followed by a short-leg walking cast for a total of 3 to

4 weeks, depending on the extent of the soft tissue resection.

 

 

 

 

FIG 2 • Clinical photographs taken 3 years after the surgery. A,B. This patient has no significant difference in dorsiflexion and plantarflexion of the ankle compared with the contralateral leg. C. This patient was able to raise her heel from the floor without pain.

 

 

Patients who underwent reconstruction of the Achilles tendon with Gore-Tex graft should be immobilized in an ankle—foot orthosis for an additional 8 weeks.

 

Rehabilitation includes leg strengthening, balance, and gait training (FIG 2).

 

 

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OUTCOMES

There have been only a few reported cases of soleus muscle resections for sarcomas. Reconstruction with a Gore-Tex graft allows the patient an almost normal gait (heel-toe, push off) and an almost normal range of motion of the ankle.

Local recurrence may require an amputation.

 

 

COMPLICATIONS

The most common complications are flap necrosis and tumor recurrence. Vascular occlusion of the posterior tibial artery is rare.

Radiation therapy should be deferred a few weeks to permit the Gore-Tex graft to heal.