Muscle Injuries

History:

• •Acute onset pain during a specific activity - patient identifies the exact moment. Sudden sharp or tearing pain during sprinting, kicking, jumping, changing direction, or explosive movement.
• •Mechanism: eccentric overload - ask about sprinting, kicking, lunging, or rapid direction change.
• •Severity at onset: could the patient continue (minor), stop immediately (moderate+), feel a 'pop' (significant tear), or fail to weight-bear (severe/complete).
• •Location: the patient points to the exact area (proximal hamstring, mid-belly, distal thigh, medial calf, anterior thigh).
• •Bruising tracking distally over hours to days = intramuscular haematoma tracking along fascial planes, indicating significant disruption.
• •Ask about previous injuries at the same muscle (strongest recurrence risk), sport, point in match (fatigue), warm-up, and medications (anticoagulants).

DOMS vs structural injury: DOMS is diffuse, bilateral, delayed (24-72 hours after unaccustomed eccentric exercise), without a specific injury event, with no focal tenderness or ecchymosis, and is self-limiting in 3-7 days. Structural injury is acute, focal, unilateral, with loss of function and possible ecchymosis or palpable defect.

Examination:

• •Inspection: swelling, ecchymosis (may take hours to days), muscle asymmetry, retracted belly with 'bunching' in complete tears.
• •Palpation: focal tenderness at the injury site - the most important finding. Palpate origin to insertion; palpable defect suggests significant disruption. Pain-free palpation is also a return-to-sport criterion.
• •Active ROM with pain and weakness; complete inability to activate suggests complete tear.
• •Passive stretch produces pain at end range (e.g. SLR for hamstring) - do NOT force in the acute phase.
• •Resisted contraction in shortened and lengthened positions; weakness and pain on resisted contraction in the lengthened position is particularly significant. Pain on BOTH resisted contraction AND passive stretch is highly suggestive of structural muscle injury.
• •Askling H-test (active knee extension with hip flexion to discomfort) is used to assess hamstring readiness during return-to-sport testing.
• •Functional testing later (walking, jogging, single-leg balance, hop testing) informs return-to-sport decisions.

Differential diagnoses: tendon rupture (sudden loss of function with palpable gap); referred lumbar spine pain; sciatic nerve-related pain; bone stress injury (focal bony tenderness, insidious); DVT (calf pain with swelling, risk factors); acute compartment syndrome; contusion (direct trauma rather than eccentric mechanism).

Many muscle injuries are diagnosed clinically. Imaging is used when the diagnosis is uncertain, to grade severity, to inform prognosis (especially in professional athletes), to exclude alternative pathology, and to assess complications. Imaging is particularly indicated when there is significant functional loss, suspicion of complete tear or tendon avulsion, elite athlete prognostic planning, or failure to progress in rehabilitation.

• •Clinical diagnosis is often sufficient for a typical minor strain with clear mechanism and mild functional loss.
• •Ultrasound (the most commonly used UK modality): accessible, dynamic, relatively inexpensive, clinic-based. Demonstrates fibre disruption, haematoma, tear extent and location. Dynamic assessment is a major advantage. Operator-dependent and may underestimate extent compared with MRI for deep injuries. USS at 48-72 hours often gives a clearer picture, although earlier USS is still useful for significant tears and haematomas.
• •MRI: provides the most detailed and reproducible classification - extent, location, intramuscular tendon involvement (the BAMIC 'c' modifier predicting longer recovery), and assessment of deep injuries (proximal hamstring, hip flexors). Particularly valuable for grading severity, identifying intratendinous involvement, assessing tendon avulsion, and when USS is inconclusive. Imaging is often performed at 24-72 hours - very early MRI may overestimate extent because of reactive oedema.
• •Plain radiographs: not useful for muscle belly injuries themselves. Consider if a bony avulsion is suspected (proximal hamstring from the ischial tuberosity, particularly in adolescents with unfused apophysis).
• •Bloods: not routine. Consider CK and renal function if rhabdomyolysis is suspected (severe crush injury, exertional rhabdomyolysis with disproportionate pain, swelling, or dark urine).

PEACE and LOVE (Dubois and Esculier, 2020) is a modern, widely used framework that emphasises early loading and education in contrast to traditional RICE/PRICE approaches. Compression and elevation from the older frameworks remain pragmatically used.

PEACE (immediate / acute, first 1-3 days):

• •Protect: avoid activities that increase pain in the first few days; brief protection, not prolonged rest; crutches for significant lower limb injuries.
• •Elevate above the heart to reduce swelling.
• •Avoid anti-inflammatories routinely in the early phase where possible - the inflammatory response is necessary for repair, and aggressive suppression may impair healing. Clinical evidence is mixed; short courses for significant pain may be used pragmatically. Cryotherapy may be used for short-term analgesia.
• •Compress with bandaging to limit swelling.
• •Educate: realistic expectations, address fear-avoidance, explain the benefits of early loading.

LOVE (subacute, from days 3-5):

• •Load: progressive loading should begin early - optimal loading stimulates repair, aligns collagen, and restores capacity.
• •Optimism: psychology strongly influences recovery - address catastrophising and fear of re-injury.
• •Vascularisation: pain-free aerobic exercise promotes blood flow and maintains fitness.
• •Exercise: therapeutic exercise is the primary treatment.

Pharmacological adjuncts: paracetamol throughout; topical NSAIDs for comfort. Avoid routine systemic NSAIDs in the first 48-72 hours; short courses thereafter may be considered if pain limits rehabilitation; prolonged use is not recommended. No role for strong opioids.

Haematoma management: small haematomas resolve with compression and elevation. Large intramuscular haematomas may be considered for USS-guided aspiration after 48-72 hours (when liquefied) - evidence for improved outcomes is limited and practice varies. Intermuscular haematomas (blood tracking between muscles, with distal ecchymosis) generally carry a better prognosis than contained intramuscular haematomas.

Myositis ossificans: bone forming within injured muscle - most often after quadriceps contusion. Risk factors include large haematoma, premature aggressive stretching or massage in the acute phase, and re-injury. X-ray shows peripheral 'zonal phenomenon' calcification (mature bone peripheral, immature centrally) - helps distinguish from malignancy. Surgical excision only after full maturation (12-18 months) if function is significantly limited.

Surgical management is indicated for: complete proximal hamstring avulsion (particularly multi-tendon avulsions or significant retraction in active individuals); complete rectus femoris avulsion in athletes; distal biceps avulsion; Achilles rupture (operative or non-operative options); complete quadriceps or patellar tendon rupture.

Acute compartment syndrome is a surgical emergency - pain out of proportion and pain on passive stretch are the earliest signs; urgent fasciotomy is required.

Referral: not usually needed for minor (Grade 1-2) injuries in primary care or SEM. Refer for complete tears or tendon avulsions, large haematomas, suspected compartment syndrome (emergency), recurrent injuries, or diagnostic uncertainty.

Progressive loading rehabilitation is the cornerstone. Restore strength AND fascicle length, particularly in hamstring injuries. Return to sport is CRITERIA-BASED, not time-based.

Phase 1 - Protection and early activation (0-5 days): PEACE framework. Compression, elevation. Gentle isometric activation within pain-free range from day one (promotes aligned collagen). Maintain cardiovascular fitness with non-provocative cross-training (cycling, swimming, upper body). Gentle ROM within comfortable range; do NOT force stretching or use deep tissue massage in the acute phase (myositis ossificans risk). Reassure and set realistic expectations.

Phase 2 - Progressive loading and ROM restoration (5 days to 2-3 weeks): progressive isotonic strengthening starting in the inner range and progressing through mid-range to outer (lengthened) range - the lengthened position is most provocative; progress gradually. ECCENTRIC strengthening is critically important because eccentric overload is the primary injury mechanism; begin slow and controlled at low load, progress to higher loads and faster speeds. Restore full ROM with gentle active and passive stretching. Address kinetic chain contributors (hip stability for hamstrings; hip flexor and core for rectus femoris).

Phase 3 - Functional progression (2-4 weeks Grade 1; 4-8 weeks Grade 2): running progression - straight-line jogging then tempo then acceleration/deceleration then change of direction then sprinting. Progress each stage only when pain-free. Sport-specific drills (kicking, jumping, cutting, pivoting). High-speed running is the most critical functional test for hamstring injuries - the muscle must tolerate near-maximal sprint before competition return; most recurrences occur because athletes return before achieving full sprint capacity. Plyometric loading; Askling H-test for hamstring readiness.

Phase 4 - Return to sport (criteria-based):

• •Pain-free during all functional testing, including maximal sprint or sport-specific activity.
• •Pain-free on palpation of the injury site.
• •Full ROM compared contralaterally.
• •Strength restored typically to 90% or more of the contralateral side - tested both concentrically and eccentrically. In elite sport, isokinetic dynamometry (e.g. Biodex) is used to measure limb symmetry objectively.
• •Completed full sport-specific training without symptoms.
• •Psychological readiness - confidence during explosive movements (validated tools where available).
• •Passed a functional testing battery (hop tests, agility, maximal sprint).

Approximate timelines (criteria-based return is paramount; these are guides): Grade 1 1-3 weeks; Grade 2 4-8 weeks (longer for proximal MTJ or intratendinous BAMIC 'c' injuries); Grade 3 / complete 8-16+ weeks; post-surgical tendon avulsion 4-6+ months.

Injury prevention and recurrence reduction:

• •Nordic hamstring exercise: the most evidence-based intervention - reduces hamstring injury rates by ~50-70% when consistently implemented (FIFA 11+).
• •Training load management to avoid sprint-volume spikes.
• •FIFA 11+ active warm-up programme reduces overall injury rates by ~30-50%; dynamic warm-up is preferred over static stretching alone for injury prevention.
• •Fully rehabilitate previous injuries - scar tissue creates a new stress concentration.

• •British Athletics Muscle Injury Classification (BAMIC) - the MRI-based system used in UK elite sport; the 'c' modifier identifies intratendinous injuries with longer recovery and higher recurrence.
• •Munich Consensus classification (Type 1-4) - the alternative international framework also referenced in the literature.
• •PEACE and LOVE framework (Dubois and Esculier, 2020) - the modern soft-tissue injury management approach emphasising early loading and education over passive rest.
• •Nordic hamstring exercise evidence base (FIFA 11+ programme) - reduces hamstring injury rates by ~50-70% when consistently implemented.
• •Askling H-test - active hamstring flexibility test used in return-to-sport assessment, particularly in UK SEM practice.

• •MTJ is the most common site of structural injury; bi-articular muscles (hamstrings, rectus femoris, gastrocnemius) are most vulnerable.
• •Two hamstring mechanisms: sprinting (biceps femoris long head, late swing) vs stretching (semimembranosus, longer recovery).
• •BAMIC 'c' (intratendinous) injuries have the longest recovery and highest recurrence; simple Grade 1-3 still used clinically.
• •Previous injury at the same site is the strongest predictor of recurrence.
• •PEACE and LOVE replaces RICE/PRICE; avoid routine NSAIDs in the first 48-72 hours.
• •Return to sport is CRITERIA-BASED: pain-free, full ROM, strength 90% or more, pain-free maximal sprint.