Sprains and strains
Exam Tips
- In OSCEs, state that sprain/strain diagnosis is clinical but fracture must be excluded using Ottawa rules and focused examination.
- A reported 'pop' with immediate dysfunction should trigger concern for ACL tear or severe hamstring/tendon rupture rather than a simple strain.
- Always document neurovascular status distal to injury and repeat after support/immobilization.
- Bruising can be delayed, so early absence of ecchymosis does not exclude significant soft-tissue injury.
- Mention recurrence prevention: early rehab, proprioceptive training, and graded return-to-play are high-yield management points.
Definition
A sprain is an acute injury to a ligament caused by excessive force across a joint, ranging from microscopic fibre stretch to complete rupture with instability. A strain is an injury to muscle fibres and/or tendon from overstretching or forceful contraction, with severity from minor fibre disruption to full-thickness tear and functional loss.
Pathophysiology
Sprains occur when joint loading exceeds ligament tensile capacity (commonly inversion/internal rotation at the ankle), producing collagen fibre disruption, bleeding, inflammatory mediator release, oedema, pain, and reflex muscle inhibition. Strains result from eccentric overload (for example, sprint acceleration in hamstrings) or sudden overstretch, causing myofibrillar and myotendinous damage followed by inflammation, satellite-cell repair, and remodelling; inadequate rehabilitation predisposes to scar-related stiffness and recurrent injury. Clinical grading helps predict function: sprain grades I-III (stretch to complete rupture) and strain degrees 1-3 (few fibres to complete tear). For anatomy revision, see figure of lateral ankle ligament complex (ATFL/CFL/PTFL) from page X in your MSK textbook.
Risk Factors
- Frequent sport participation, especially contact or rapid acceleration/deceleration sports
- Previous sprain/strain (strong predictor of recurrence)
- Poor conditioning: reduced strength, flexibility, coordination, proprioception, and balance
- Inadequate warm-up/cool-down, overtraining, and insufficient recovery
- Poor technique, biomechanical malalignment, joint laxity, flatfoot, neuromuscular deficits
- Inappropriate or worn footwear; uneven playing surfaces or inadequate equipment
- Increasing age (notably calf strain risk), obesity (joint load), and underweight (ankle sprain risk)
- Neuropathy, alcohol excess, or sedating drugs increasing falls/injury risk
Clinical Features
Symptoms
- Acute pain after twist, fall, blow, or sudden acceleration
- Swelling, reduced function, and difficulty weight-bearing
- Bruising (may be delayed up to 24 hours)
- Sprain pattern: localized joint pain/tenderness with possible giving way
- Strain pattern: muscle pain, cramp/spasm, weakness; possible sudden 'pop' in severe tear
- Persistent instability, recurrent episodes, or prolonged pain suggesting severe injury/complication
Signs
- Localized tenderness over ligament, tendon, or muscle belly
- Joint effusion/oedema, ecchymosis, and painful reduced active/passive range of motion
- Loss of power (especially in moderate-severe strain)
- Mechanical laxity on stress testing (for example positive anterior drawer in ankle sprain)
- Antalgic gait or inability to bear weight 4 steps
- Red flags: deformity, neurovascular deficit, disproportionate pain/tense compartment, fever/hot joint
Investigations
Management
Lifestyle Modifications
- Use early protection and relative rest with ice, compression, and elevation in the acute phase; avoid prolonged immobilization unless instability is significant
- Begin graded loading/physiotherapy early (range-of-motion, strength, balance, proprioception) to reduce recurrence and chronic instability
- Temporarily modify sport/work; structured return-to-play only when pain, strength, and function have recovered
- Consider bracing/taping in high-risk sports or recurrent ankle sprain
- Safety-net: urgent review for worsening pain/swelling, inability to weight-bear, numbness, cold/pale limb, fever, or severe night pain
Pharmacological Treatment
Simple analgesic
- Paracetamol 1 g orally every 4-6 hours when required (maximum 4 g/day in adults)
First-line for pain if NSAIDs are unsuitable; reduce maximum dose in low body weight, frailty, or hepatic impairment; avoid duplicate paracetamol-containing products.
NSAID (oral)
- Ibuprofen 400 mg orally three times daily with food (lowest effective dose, shortest duration)
Useful for pain/inflammation after acute soft-tissue injury. Avoid/caution in active peptic ulcer disease, significant CKD, heart failure, uncontrolled hypertension, anticoagulant use, NSAID-exacerbated asthma, and third-trimester pregnancy; consider gastroprotection (e. g, omeprazole 20 mg daily) if GI risk is elevated.
NSAID (topical)
- Diclofenac gel 1-2.32% applied to affected area 2-4 times daily (follow product limits)
- Ibuprofen gel 5-10% applied up to three times daily
Can reduce systemic adverse effects compared with oral NSAIDs; avoid on broken skin and in known NSAID hypersensitivity.
Short-course opioid rescue (if severe pain and other options inadequate)
- Codeine phosphate 30-60 mg orally every 4-6 hours when required (maximum 240 mg/day)
Use only brief courses; counsel on sedation, constipation, nausea, driving impairment, and dependence risk; avoid with significant respiratory depression.
Surgical / Interventional
- Urgent orthopaedic referral for complete rupture with gross instability, suspected tendon avulsion/complete tendon rupture, associated fracture-dislocation, or failed conservative management
- Emergency fasciotomy if compartment syndrome is suspected
- Selected ligament reconstruction/repair for persistent instability after structured rehabilitation
Complications
- Recurrent sprain/strain and chronic instability (especially lateral ankle)
- Persistent pain, swelling, weakness, and reduced function
- Post-traumatic osteoarthritis after recurrent or severe ligament injury
- Muscle atrophy, fibrosis, and prolonged stiffness after inadequate rehabilitation
- Compartment syndrome (limb-threatening emergency)
- Haemarthrosis or, less commonly, septic arthritis after joint injury
- Complex regional pain syndrome
- Charcot arthropathy risk in people with diabetes and neuropathy
- Heterotopic ossification after severe soft-tissue trauma
Prognosis
Outcome is mainly severity-dependent: mild injuries often recover within weeks, moderate injuries usually recover over weeks but have high re-injury risk in the first 4-6 weeks, and severe injuries may require months and sometimes surgery. Early symptom control plus progressive rehabilitation improves return-to-function and reduces recurrence; recovery is slower with prior injury, poor rehab adherence, obesity/diabetes, or premature return to sport.
Sources & References
🏥BMJ Best Practice(1)
✅NICE Guidelines(1)
- Sprains and strains[overview]