Diagnostic Considerations
The following conditions can be confused with a gastrocnemius strain:
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Baker cyst rupture
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Deep venous thrombosis
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Plantaris tendon rupture
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Acute compartment syndrome after rupture of the medial head of the gastrocnemius
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Chronic exertional compartment syndrome (posterior)
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Posterior tibial tendon rupture or tendinitis
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Popliteal artery entrapment syndrome
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Anomalous gastrocnemius muscle rupture
A Baker cyst is a reactive outpouching of the knee joint capsule. The presence of a Baker cyst implies chronic internal knee pathology, often arthritic in nature, but it may also include traumatic meniscal pathology. The cyst is usually painless but often cosmetically unacceptable to the patient. If the Baker cyst ruptures, the leg swells, and the pain is diffuse. This condition can be confused with a ruptured gastrocnemius muscle.
(See also the Medscape Reference articles Baker Cyst [in the Radiology section], Knee Injury, Soft Tissue [in the Emergency Medicine section], and Cystic Lesions About the Knee and Limping Child [in the Orthopedic Surgery section].)
A femoral or popliteal deep venous thrombosis (DVT) can cause leg swelling, which can result in leg pain. If this condition occurs in the same time frame as an acute leg injury, the 2 conditions can be confused.
(See also the Medscape Reference articles Deep Venous Thrombosis and Thrombophlebitis [in the Emergency Medicine section] and Deep Venous Thrombosis, Lower Extremity [in the Radiology section].)
The plantaris tendon originates in the popliteal area, and this tendon is also a plantar flexor of the ankle. If the plantaris tendon ruptures, the leg swells, and the resulting tenderness can be in the same area as where a gastrocnemius strain would occur.
Achilles tendon injury can occur with the identical mechanism of a medial gastrocnemius rupture. Because the ensuing fluid and edema may migrate proximally, the 2 conditions may mimic each other. An Achilles tendon rupture results in an inability to plantar flex the foot, and a more distal defect of the tendon is usually palpable. A Thompson test can be used to differentiate the 2 injuries. The test is performed with the patient prone and the knee held in flexion. Then, the gastrocnemius muscle is squeezed. A negative sign results in normal plantar flexion of the foot and ankle. If the flexion is not appreciated, the test is positive and due to a disrupted Achilles tendon. (See also the Medscape Reference article Achilles Tendon Rupture.)
Acute compartment syndrome of the lower extremity occurs after trauma, with accumulation of blood or fluid in a closed compartment of the leg. The resultant pressure produces pain and swelling, and if the posterior compartment is affected, this could clinically present similarly to a medial gastrocnemius tear. A case study by Tao et al recommends that clinicians should have a high index of suspicion for atraumatic compartment syndrome, and timely surgical fasciotomy must be undertaken to avoid complications resulting from delayed diagnosis and treatment. [9]
(See also the Medscape Reference articles Compartment Syndrome, Lower Extremity [in the Orthopedic Surgery section], Compartment Syndrome [in the Physical Medicine and Rehabilitation section], and Compartment Syndrome, Extremity [in the Emergency Medicine section].)
Chronic compartment syndrome results in affected individuals after a degree of exertion and from vascular compromise with edema in the compartment of the leg. The pain that ensues can mimic that of gastrocnemius muscle strains, but this condition becomes symptom-free after the exertion is completed. (See also the Medscape Reference article Compartment Syndromes [in the Sports Medicine section].)
The popliteal tendon courses posteriorly on the medial side of the leg. Injuries to this structure can distribute pain in the same regions as a tennis leg injury. (See also the Medscape Reference articles Pes Planus [in the Orthopedic Surgery section] and Athletic Foot Injuries [in the Sports Medicine section].)
The popliteal artery may be entrapped during its course in the leg. The most common cause is an anomalous gastrocnemius muscle. Typically, popliteal artery entrapment manifests during exertion, and the symptoms of this condition are more consistent with the symptoms of chronic exertional compartment syndrome.
(See also the Medscape Reference articles Peripheral Arterial Occlusive Disease [in the Vascular Surgery section], Compartment Syndrome, Lower Extremity [in the Orthopedic Surgery section], and Compartment Syndromes [in the Sports Medicine section].)
Differential Diagnoses
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Achilles Tendon Rupture
