The gastrocnemius muscle consists of 2 heads. The medial head originates from the posterior medial femoral condyle while the lateral head arises from the posterior lateral femoral condyle. The gastrocnemius muscle is vulnerable to injury because it crosses 3 joints: knee, ankle and subtalar joint. The medial and lateral heads of the gastrocnemius muscle arise from 2 separate proximal attachments on the posterior aspect of the femoral condyles. Distal to the myotendinous junction, the gastrocnemius muscle becomes a flat aponeurosis and coalesces with the soleus aponeurosis to form the Achilles tendon. While Achilles tendon injury is common, injury over the posterior calf, including the gastrocnemius, soleus, plantaris, and flexor hallucis longus muscles, are far less prevalent. Proper and timely differential diagnosis is essential to treat patients with posterior calf injuries. Patients generally recover well if they received appropriate diagnosis and treatment.
The injury usually develops at the posture of the knee, in other words, during maximally extension and ankle fully dorsiflexion, which maximally stretches the gastrocnemius muscle. The posture increases the tension of the elastic elements of the muscle to let them approach the threshold of muscle tear, especially during eccentric contraction of the muscle.
Gastrocnemius strain occurs most commonly in the middle-aged or older patients. Gastrocnemius strain may also occur in younger athletes as named "tennis leg." The term is derived from the posture to serve tennis, which involves maximal knee extension and ankle dorsiflexion. The medial head of the gastrocnemius muscle is injured more commonly than the lateral head as some studies have shown the muscular activity to be more active at the medial head than the lateral head.
Gastrocnemius injury is common in young athletes practicing exercises such as racquet sports, running, basketball, football, and skiing. One report described that this injury happened following praying namaz. The activity mentioned above requires the participant to kneel with the head touching the group. The calf muscle is eccentrically stretched when the participant attempts to stand up.
Muscle fatigue and impaired coordination are common factors contributing to gastrocnemius muscle strain. Some research revealed that impaired vascular supply to the gastrocnemius muscle might result in weakness of the musculotendinous unit. Failure of muscle relaxation also plays a role in causing muscle strain. Due to the inability to fully relax, muscle fibers are more vulnerable to stretching injury.
The associated symptom includes muscle stiffness, indicating a decline of muscular elasticity. A common prodrome before the injury event comprises of a dull muscle ache.
Typically, the patient feels something stricken on the calf. Accompanying this feeling is an audible snap, sounding like breaking a twig. At the moment of injury, there may be no pain. After the victim takes a few steps, the pain develops on the posteromedial part of the calf. Intense pain may make patients unable to walk.
Prodromal symptoms play an interesting role in gastrocnemius muscle injury. Patients may recall similar prodromic discomfort. There might be dull pain first noted on the affected calf. One report states that 20% of patients experience prodromic symptoms.
The physical finding includes ecchymosis and tenderness over muscle tear site. A subcutaneous gap may be palpated if there is a frank retraction across the injury site. The patient may have severe pain during passive stretching the calf or resistive plantar flexion.
Imaging studies can assist in differentiating partial and complete ruptures. The utility of plain films and computed tomography scans in soft tissue injury is limited. Ultrasound offers the advantage of nonionizing radiation and is relatively inexpensive. The examiner should be aware of sonographic findings such as the disruption of the normal fiber arrangement at the myotendinous junction, hematoma, and fluid collection between the gastrocnemius and soleus muscles. Ultrasonography can also differentiate partial from complete tears of the muscle, determine the size of the hematoma. A bigger hematoma usually indicates complete gastrocnemius muscle tear rather than partial tear. Ultrasound can also determine the size of a complete rupture and is helpful in guiding percutaneous aspiration of the hematoma. Deep vein thrombosis can also be scrutinized by using ultrasound, which is sometimes concomitant with gastrocnemius strain.
One study of 141 patients with clinically diagnosed tennis leg showed that 67% had a partial tear of medial gastrocnemius, 1.4% had associated plantaris tendon rupture, and 21% had intermuscular fluid collection without medial gastrocnemius muscle tear. Ten percent had deep vein thrombosis without visible gastrocnemius pathology.
Sonography is useful to follow up the healing course. Signs of recovery on sonography include a progressive decrease in the hematoma size, reparative tissue signified by a peripheral hypoechoic area that extends toward the center, and rearrangement of muscle fibers.
Magnetic resonance imaging (MRI) is indispensable in certain conditions as it offers outstanding soft tissue imaging. Findings include rupture or discontinuity of muscle fibers and retraction of the torn muscle fibers. MRI also allows differentiation between gastrocnemius and Achilles tendon injury, which can help to improve direct treatment. MRI can also provide an assessment of surrounding connective tissues in some muscle injury cases. Three MRI studies reported that connective tissue injury plays an important role to evaluate the return to sports after muscle injury.
Early treatment emphasizes symptomatic relief. Limiting further bleeding, decreasing pain and preventing joint contracture are the main goals of early management of the gastrocnemius strain. Rest, ice packing, compressive wrapping, and elevation are common measures to minimize swelling and pain of injured muscle.
Medications may be necessary to reduce pain and muscle spasm. Early mobilization is also paramount for preventing contracture. Non-steroid anti-inflammatory drugs are not recommended within the first 24 to 72 hours of injury due to an increased risk of bleeding from their antiplatelet effects. Celecoxib and possibly other COX-inhibitors are possible options during this period due to their weaker antiplatelet effect. Acetaminophen or narcotic pain medication can also be used.
It is important to prescribe physical therapy to promote functional recovery. Initially, gentle stretching can help lengthen the intramuscular scar of the injured muscle. Later, strengthening, heel raising and proprioceptive exercise should be added as well as core muscles strengthening and general reconditioning. The patient is allowed to ambulate as tolerated and to increase the activity level gradually after the pain subsides. In patients suffering from severe injury, weight bearing of the affected lower extremity should be limited, and a cast or orthosis may be needed for ambulation. Weight-bearing exercise or dorsiflexion stretching should be delayed until the pain subsides.
Most patients recover well under non-operative treatment. Surgical repairing of the muscle tear may be needed in certain cases. But the procedure is technically challenging due to the difficulty of performing a suture through muscle tissue. Fibrosis and contracture at the incision site appear to be another concern. The absolute surgical indication is still unclear.
The differential diagnosis includes:
Among calf muscle injuries, injury of the medial head of the gastrocnemius muscle remains the most frequent. Plantaris strain is relatively rare. Soleus muscle has a lower risk of injury in contrast to the gastrocnemius muscle. The soleus muscle mainly consists of type 1 slow twitch muscle fibers and crosses only the ankle joint. Soleus strain tends to be less severe than gastrocnemius strain.
Grade 1 Injury (Mild)
The patients may feel a sharp pain at the time of injury or pain with activity. They are usually able to continue the activity. There may be no or minimal loss of strength and range of motion. One MRI study exposes bright signals on fluid-sensitive sequences with less than 5% feathery appearance of muscle fiber involved. Pathologically, grade 1 injury indicates less than 10% of muscle fibers disrupted.
Grade 2 Injury (Moderate)
The patient cannot walk at the moment of injury. The patient may complain of weakness during ankle dorsiflexion and plantar flexion. One MRI study concedes the change in myotendinous junction as edema or hemorrhage. Grade 2 injury implies 10% to 50% disruption of muscle fibers.
Grade 3 Injury (Severe)
There may be a palpable defect on the affected calf. The MRI findings include complete disruption of continuity of muscle, wavy tendon morphology and retraction and extensive hemorrhage or edema. Dixon et al. suggested that grade 3 injury indicates 50% to 100% disruption of muscle fibers.
Most studies indicate that gastrocnemius strains mostly have a good prognosis. Most patients can have a marked decrease in pain and return to exercise after adequate management.
Gastrocnemius strain remains a common injury among young athletes and middle to older ages. Many of these patients often first present to the emergency department or the primary care provider. Hence, these professionals need to know about the diagnosis and management about the disorder. The key to preventing these injuries is patient education about the importance of warmup and stretching before the formal exercise. For most patients, the prognosis is good. Non-operative treatment often provides optimal symptoms relief and functional recovery. The indication for surgical intervention remains uncertain. (Level V)