Tears of the medial head of gastrocnemius are common, especially in the older or intermittent athlete – the so called ‘weekend warriors’. Males are more commonly implicated between their 40’s and 60’s. The term ‘tennis leg’ has been coined as it commonly occurs in this sport, but it may occur in any activity which involves a forceful push-off with the foot.
The gastrocnemii are the 2 large superficial muscles making up the bulk of the calf. They are the primary dorsi-flexors of the foot, but are also weak knee flexors. The medial one is most prone to acute injury in around 80% of cases. It may occur in instances where the player lunges forward and the back leg is straightened with the foot dorsiflexed. In this position the calf is at maximal stretch. A push off, or forceful plantar-flexion of the foot at this time places an eccentric load on the muscle, causing the muscle to tear. A tear may also occur with an excessive plantar flexion or concentric load. An important predicting factor for this injury is a previous calf tear. It may also occur in a cold, inflexible or de-conditioned muscle.
Historically the main feature of this injury is the sudden onset of calf pain during an athletic event. The patient will often say they felt they were hit in the leg by the tennis ball. There may also be an audible ‘pop’. Pain localizes in the calf, but may radiate to the knee or ankle.
On examination there may be calf swelling or bruising. Palpation will reveal exquisite tenderness in the medial calf, commonly with a palpable defect. Passive dorsi-flexion and active plantar-flexion will reproduce the pain. On palpation the Achilles tendon should be intact and Thompson’s test should be negative.
The diagnosis of a medial head of gastrocnemius tear is clinical. The most important differential diagnosis is of an Achilles tendon rupture, which again should be made clinically. If an investigation is required (generally for an elite athlete or if there is any doubt on diagnosis) then an MRI is most accurate for assessing the size and severity of the lesion. An ultrasound may show a hypoechoic region of muscle tearing and bleeding. A venous Doppler may be helpful if there is any concern about potential DVT.
Initial treatment should involve aggressive anti-inflammatory measures over the first 48-72 hours. This should include regular alteration of ice and compression, with ice for 20 minutess ever 1-2 hours. The leg should be elevated and partial weight-bearing on crutches is generally indicated. After this period passive and active ankle ROM exercises can be commenced, but should be pain free. Pain management would include simple analgesics. Anti-inflammatories may cause further bleeding or pre-dispose to subsequent episodes of calf tear. Physiotherapy with deep tissue massage is helpful to dissipate blood clot and oedema and prevent excessive scar formation.
Regaining pain free dorsiflexion range occurs first and is followed by a graduated program of calf strengthening exercises. A program of off feet training progresses to low, then high intensity running, followed by sport specific drills and return to play. This whole process may take a good 6 weeks. Continued strengthening is important to prevent re-injury.
A co-existant DVT should always be considered in a patient who is not improving as expected, has persistent calf swelling or had sub-optimal initial treatment with a late presentation.