Calf Strain

Partial tear of the gastrocnemius muscle fibres (the medial head in about 90%, "tennis leg"), and less often the soleus, usually at the musculotendinous junction. It arises during sudden forced plantarflexion with the knee extended (a lunge, sprint start, jumping, racquet sports) or forced dorsiflexion.

• Common in middle aged recreational athletes (35 to 55 years), and affects men more than women. The gastrocnemius crosses the knee and ankle and has many fast twitch fibres.
• Risk factors: age, previous calf injury, tight calf, fatigue, poor conditioning, dehydration or electrolyte disturbance, and statins and fluoroquinolones (tendon and muscle effects).
• Soleus strain is more common in runners, and causes deeper pain that is worse with the knee flexed.
• Grades: 1 (minor, less than 5% of fibres), 2 (partial tear), 3 (complete rupture).

• Sudden sharp pain in the posteromedial calf with a feeling of being struck or kicked in the leg, followed by pain on walking, tiptoe and push off, swelling and bruising that may track to the ankle.
• Tenderness at the musculotendinous junction of the medial head, pain on passive dorsiflexion with the knee extended, pain and weakness on resisted plantarflexion and heel raise, with a palpable defect in major tears.
• Soleus strain: deeper pain, worse with the knee flexed 90 degrees.
• Red flags for other diagnoses: calf pain and swelling at rest with warmth and a positive Homans like tenderness (deep vein thrombosis), a palpable gap in the Achilles tendon with a positive Thompson (squeeze) test and inability to rise on tiptoe (Achilles rupture), tense swollen painful calf with pain on passive stretch and neurovascular signs (compartment syndrome), and a ruptured Baker cyst (sudden calf pain and swelling in a patient with knee arthritis).
• Differential diagnosis: deep vein thrombosis, Achilles tendon rupture or tendinopathy, plantaris rupture, ruptured popliteal cyst, compartment syndrome, tibial stress fracture, nerve entrapment, claudication, lumbar radiculopathy, and a muscle tumour.
• Complications: re-injury, chronic scarring, haematoma, compartment syndrome (rare), deep vein thrombosis, and persistent weakness.

• Clinical, with a Thompson test (squeezing the calf with the patient prone should plantarflex the foot, which is absent in Achilles rupture).
• Ultrasound is the main test: it shows a partial tear, fluid collection between the gastrocnemius and soleus, and distinguishes it from a ruptured popliteal cyst and deep vein thrombosis. Duplex ultrasound of the leg veins for any suspected deep vein thrombosis, using clinical risk scoring and D-dimer where appropriate.
• MRI for unclear diagnosis, suspected complete tear, or elite athletes.
• Compartment pressure measurement if compartment syndrome is suspected (an emergency).
• Check creatine kinase if there is diffuse pain, dark urine or a statin history.

• First 48 to 72 hours: protect, relative rest, ice for 10 to 15 minutes every 2 to 3 hours, compression bandage, and elevation. A heel raise of 1 to 2 cm in both shoes (or a walking boot) reduces calf tension for 1 to 2 weeks. Crutches if weight bearing is painful.
• Analgesia: paracetamol 1 g orally 6 hourly, with a short course of ibuprofen 400 mg orally 8 hourly with food for 3 to 5 days, if no contraindication.
• Rehabilitation:
  • Early (days 2 to 7): pain free active ankle range of movement, gentle isometric plantarflexion, and walking with a heel lift.
  • Intermediate (weeks 1 to 3): gentle calf stretching (knee extended for gastrocnemius, knee flexed for soleus), double leg then single leg heel raises (progress from 3 sets of 10 to 15), cycling and swimming.
  • Advanced (weeks 3 to 6): eccentric heel drops from a step (3 sets of 15, once or twice daily), jogging, hopping, plyometrics and sprinting.
  • Return to sport when pain free with full range, equal strength (able to perform 20 or more single leg heel raises), and sport drills passed.
  • Typical return: grade 1, 1 to 3 weeks. Grade 2, 3 to 6 weeks. Grade 3, 6 to 12 weeks.
• Large haematoma: ultrasound guided aspiration may be considered for a tense collection causing pain and slow recovery.
• Deep vein thrombosis if found: apixaban 10 mg orally twice daily for 7 days then 5 mg twice daily, or rivaroxaban 15 mg twice daily for 21 days then 20 mg daily, for at least 3 months, with the usual precautions.
• Achilles tendon rupture: urgent orthopaedic referral for functional bracing in equinus with early weight bearing, or surgical repair.
• Compartment syndrome: urgent fasciotomy.
• Surgery for calf strain is rarely needed (chronic painful haematoma or complete muscle rupture in athletes).
• Prevention: warm up, calf stretching and strengthening, gradual increase in training load, hydration, and appropriate footwear. Review fluoroquinolone and statin use if recurrent.
• Special groups:
  • Elderly: lower threshold for Doppler ultrasound, check arterial supply, and avoid NSAIDs if renal impairment, heart failure or peptic ulcer.
  • Pregnancy: rest, elevation, paracetamol, and ultrasound for any unilateral leg swelling because of the increased thrombosis risk. Avoid NSAIDs after 20 weeks.
  • Anticoagulation: haematoma and bleeding risk, so seek review if swelling expands.
• Follow up: review at 1 to 2 weeks, and sooner if swelling or pain worsens. Refer to sports medicine or orthopaedics for suspected tendon rupture, large haematoma, no improvement by 3 weeks, or recurrent injury.