Acute Muscle Strains & Tears

The sudden “twang” during sport or a lunging movement — hamstring, calf, quadriceps or groin. Most are managed entirely in general practice; the job is grading severity, excluding the mimics that matter (DVT for a calf strain), and setting realistic expectations for return to activity.

For chronic tendinopathy see Tendinopathies & Bursitis; for generic soft-tissue first aid principles see Acute Soft-Tissue Injury Management.

Grading — the same three-point scale for any muscle

• Grade 1 (mild): fewer than 10% of fibres disrupted; mild pain or swelling, little or no loss of function.
• Grade 2 (moderate): identifiable partial tear with moderate pain and swelling, and a genuine loss of function.
• Grade 3 (severe): complete disruption of the muscle or its tendon, severe pain and swelling, and inability to use the muscle. A palpable defect in the muscle belly, or a “pop” felt at the time of injury with immediate loss of function, points to this grade.

Hamstring

Suspect it with sudden posterior thigh pain during sprinting, a stiff-legged gait avoiding hip and knee flexion, and difficulty weight-bearing. A proximal tear near the ischial tuberosity causes pain sitting down and point tenderness at the ischial tuberosity; bruising down the back of the thigh often only appears over the following days. Test resisted knee flexion prone with the hip at neutral extension, comparing both sides — pain or weakness is a positive finding.

X-ray to exclude an apophyseal avulsion fracture, particularly in an adolescent. Ultrasound or MRI settle grade and extent when it matters for planning (recurrent injury, elite return-to-sport, uncertain diagnosis), but is not required for a straightforward grade 1–2 strain.

Grade 1–2 injuries are managed non-operatively: rest, ice, relative immobilisation for the first 3–5 days to control bleeding and swelling, then progressive weight-bearing, stretching and strengthening. NSAIDs help pain but should not be used beyond about a week. Grade 3 complete tears with more than 2 cm retraction have a poor outcome without surgery — refer for a surgical opinion rather than trialling conservative management first.

Return to sport is reasonable once hamstring strength on the injured side reaches around 90% of the uninjured side and the hamstring-quadriceps strength ratio is roughly 50–60%. Returning before flexibility and strength are restored is the main driver of the high hamstring re-injury rate. A previous hamstring injury is the strongest single risk factor for another one, raising the risk of reinjury roughly sixfold. A hamstring-to-quadriceps strength ratio below 0.6 on the injured side is the key modifiable contributor to that risk and is exactly what a graded strengthening programme targets.

Calf — gastrocnemius strain (“tennis leg”)

Classically the medial head of gastrocnemius, from forceful ankle dorsiflexion with the knee extended (the tennis serve position, but seen just as often kneeling then standing, or in racquet sports and running). Patients often describe feeling struck in the calf with an audible pop, then pain developing over the next few steps. Examine for tenderness over the medial gastrocnemius belly or musculotendinous junction, and palpate the Achilles tendon specifically (or use the Thompson test) to exclude a concomitant Achilles rupture.

Actively consider DVT — one series of patients with clinically diagnosed tennis leg found 10% had a DVT with no visible gastrocnemius tear at all, and DVT can also coexist with a genuine muscle tear. A disproportionately swollen, tender calf, risk factors for VTE, or a clinical picture that doesn’t fit cleanly with a muscle strain should prompt compression ultrasound rather than assuming muscle injury.

Management mirrors hamstring strain — rest, ice, compression, elevation; avoid heat or massage early, which can increase bleeding into the haematoma. Most recover well without surgery.

Quadriceps and adductor (groin) strains

Quadriceps strains most often affect rectus femoris (it crosses both hip and knee) from a kicking or sprinting mechanism; adductor strains follow a forceful change of direction or overstretch, particularly in football-code sports. Both follow the same grading system and the same core management (rest/ice/progressive loading) as hamstring and calf strains above. A muscle-belly strain is different from a tendon avulsion or rupture at the muscle’s attachment — see Extensor Mechanism Ruptures for sudden inability to straight-leg-raise with a palpable gap, which needs urgent same-service referral rather than the conservative pathway here.

Red flags for referral, not routine management

• Suspected grade 3 tear with significant retraction or a palpable defect — surgical opinion, not a trial of physiotherapy first.
• A hamstring avulsion fracture, or any fracture, on X-ray.
• Neurological symptoms (numbness, weakness beyond the injured muscle) — a large hematoma can compress an adjacent nerve (e.g. the sciatic nerve after a proximal hamstring tear, or the sural nerve after a large gastrocnemius haematoma).
• A calf presentation that doesn’t add up clinically for muscle strain alone — image for DVT.