Medial Gastrocnemius Strain
A medial calf injury is a musculotendinous disruption of varying degrees in the medial head of the gastrocnemius muscle that results from an acute, forceful push-off with the foot.1, 2, 3, 4, 5, 6 This injury occurs commonly in sports activities (eg, hill running, jumping, tennis), but it can occur in any activity. A medial calf injury is often seen in the intermittently active athlete, often referred to as the “weekend warrior.”
This condition has been termed “tennis leg” because of its prevalence in this particular sport, but medial calf injury can happen in a variety of sports or other activities. One mechanism that occurs is on the back leg during a lunging shot, in which the knee is extended while the foot is dorsiflexed. This action puts maximal tension on the gastrocnemius muscle as the lengthened muscle is contracted at the “push off,” resulting in a medial calf injury. (See also the eMedicine article Body Contouring, Calf Augmentation.)
For excellent patient education resources, visit eMedicine’s Sports Injury Center and Sprains and Strains Center. Also, see eMedicine’s patient education articles Muscle Strain and Sprains and Strains.
Medial calf injuries occur more commonly in men than in women, and these injuries usually afflict athletes and others in the fourth to sixth decade of life. Medial calf injuries are most commonly seen acutely, but up to 20% of affected patients report a prodrome of calf tightness several days before the injury, thus suggesting a potential chronic predisposition.
The medial head of the gastrocnemius muscle originates from the posterior aspect of the medial femoral condyle, and as it courses distally, the medial head merges with the lateral head of the gastrocnemius. Further distally, the joined heads of the gastrocnemius merge with the soleus muscle-tendon complex to form the Achilles tendon. The main function of the gastrocnemius muscle is to plantar flex the ankle, but it also provides some knee flexion, as well as contributes to the posterior stability of the knee and partially to the motion of the menisci with flexion/extension of the knee. Throughout the belly of the muscle, the medial gastrocnemius has several origins of tendinous formation. Most strains occur at this musculotendinous junction.
The medial calf injury usually occurs when an eccentric force is applied to the gastrocnemius muscle, which usually happens when the knee is extended, the ankle is dorsiflexed, and the gastrocnemius attempts to contract in the already lengthened state.1, 2, 3, 4, 5, 6 This is the common position of the back leg in a tennis stroke, and it results in the greatest force to the muscle unit; but medial calf injuries can also occur during a typical contraction of ankle plantar flexion, especially if the athlete is pushing or lifting a large weight or force.
An audible pop when the injury to the medial calf occurred is usually reported, and the patient complains of feeling like a stick struck his/her calf.
The patient complains of pain in the area of the calf, which also radiates to the knee or the ankle. In addition, the patient complains of pain with range of motion (ROM) of the ankle.
The patient complains of a swollen leg that extends down to the foot or ankle, as well as the associated color changes of bruising. (See also the eMedicine article Contusions.)
Asymmetric calf swelling and discoloration, potentially spreading to the ankle and foot, is noted on physical examination.
If the stage of swelling has resolved, a visible defect in the medial gastrocnemius muscle may be evident.
Tenderness is noted upon palpation in the entire medial gastrocnemius muscle, but this tenderness is observed to be exquisitely more painful at the medial musculotendinous junction.
Depending on the degree of swelling, a palpable defect may be evident at the medial musculotendinous junction; however, with extreme swelling, this finding may not be appreciable.
Palpation of the Achilles tendon should demonstrate an intact tendon.
The peripheral pulses should be present and symmetric.
Provocative maneuvers: Moderate to severe pain is demonstrated with passive ankle dorsiflexion (due to stretching of the torn muscle fibers), as well as with active resistance to ankle plantar flexion (due to the firing of the torn muscle fibers).
Age/activity status: As indicated in the Background section, medial calf injuries occur more commonly in the middle-aged recreational athlete. This population typically continues to be physically active at a moderate to high intensity but not on a regular basis, and these individuals are also likely to have maintained a moderate degree of the muscle mass from their more active days. Yet weekend warriors seem to have started to lose some of the flexibility they had when they were younger, resulting in a relatively large gastrocnemius muscle that is less flexible than it had been, and on occasion, the muscle is challenged with a ballistic or explosive force, leading to a partial or complete rupture.
Deconditioned/unstretched muscles: The cold and unstretched muscles that recreational athletes often use to compete with are very likely to rupture when challenged compared with conditioned and stretched muscles. However, because medial calf injuries also occur in the physically fit, the role of stretching in prevention is not completely understood. This phenomenon may mean that force versus elasticity is the key formula, and if the force overcomes the elasticity, even in a conditioned athlete, then a rupture or injury can occur.
Previous injury: The athlete with recurrent calf strains is likely to have healed with fibrotic scar tissue, which absorbs forces differently and is thus more likely to result in rupture when the muscle is challenged.