Diagnosis, prevention and treatment of common lower extremity muscle injuries in sport, grading the evidence: a statement paper commissioned by the Danish Society of Sports Physical Therapy

Key points

1. 01This is a GRADE-graded synthesis of the best available evidence for hamstring, adductor, quadriceps, and calf muscle strains in sport.
2. 02Prevention has the strongest support: Nordic hamstring exercise programmes reduce hamstring injuries, and FIFA 11+ plus Copenhagen adductor work reduce groin injuries.
3. 03Most clinical examination tests for muscle strain showed very low to low diagnostic accuracy, so they should not be relied on alone.
4. 04Lengthening (long-muscle-length) hamstring exercises sped up return to play versus conventional rehab, but on very low to low quality evidence.
5. 05Platelet-rich plasma showed no benefit for hamstring recovery or reinjury, on moderate quality evidence.

How it was conducted

Design

Statement paper with twelve systematic searches and GRADE quality appraisal, commissioned by the Danish Society of Sports Physical Therapy

Databases

MEDLINE (via PubMed), CENTRAL, and Embase, searched July 2018 and updated September 2019

Structure

Four injury sections (hamstring, adductor, rectus femoris/quadriceps, calf), each covering diagnosis, prevention, and treatment

Evidence rule

Included the highest level of available evidence per domain, graded from high to very low quality using GRADE

What they found

• Hamstring prevention with programmes including the Nordic hamstring exercise vs usual care (n=5362): RR 0.55 (0.34-0.89), I2=67.0%, moderate quality.
• A specific Nordic hamstring protocol vs usual care (n=1521): RR 0.35 (0.22-0.54), I2=0.0%, high quality.
• FIFA 11+ vs usual care for hamstring prevention (n=3417): RR 0.39 (0.24-0.64), I2=0.0%, moderate quality.
• Lengthening hamstring exercises vs conventional exercises for time to return-to-play (n=131): Hedges' g 1.23 (0.85-1.60), I2=0.0%, low quality.
• Reinjury after lengthening vs conventional hamstring exercises (n=131): RR 0.25 (0.03-2.20), very low quality.
• Platelet-rich plasma vs placebo or rehabilitation for return-to-play (n=154): HR 1.03 (0.87-1.22), I2=75.0%, moderate quality; for reinjury (n=129): RR 0.88 (0.45-1.71), moderate quality.
• Diagnosis: pain on trunk flexion for hamstring injury LR+ 1.48 (1.12-1.97) and LR- 0.37 (0.22-0.63), moderate quality; pain on active knee flexion LR+ 1.50 (0.91-2.49), high quality.

Limitations

• The synthesis relied on the highest available evidence, which varied widely in quality across injury types and domains.
• Most outcomes for diagnosis, prevention, and treatment were graded only very low to moderate quality, so confidence in the effect estimates is limited.
• Several pooled estimates showed substantial heterogeneity (for example I2=67.0% for Nordic-inclusive prevention and I2=75.0% for PRP return-to-play).
• Diagnosis and treatment evidence for quadriceps and calf injuries was sparse and similarly low in quality.

Why it matters

For patients

Athletes are better served by injury-prevention exercise programmes such as the Nordic hamstring exercise than by relying on a single clinical test or on platelet-rich plasma injections after a hamstring strain.

For clinicians

Prioritise Nordic hamstring, FIFA 11+, and Copenhagen adductor prevention programmes, interpret muscle-strain clinical tests cautiously given their low accuracy, and do not expect benefit from PRP for hamstring injuries.

For readers

This statement maps where the evidence on muscle-strain care is solid (prevention) versus weak (most diagnosis and several treatments), flagging that further high-quality research is likely to change the estimates.