Mapping tenderness to palpation predicts return to play following acute hamstring strain

Key points

1. 01Examiners mapped the painful area by pressing along the back of the thigh and measuring how far tenderness extended, expressed as a percentage of thigh length.
2. 02Length of tenderness was the standout predictor of return to sport, while width and location were not.
3. 03Older patients took longer to return, and adding age to the equation improved the prediction.
4. 04A predictive equation lets a clinician estimate return-to-sport days from a single tape-free palpation measurement, no imaging needed.
5. 05The same relationship held no matter when during rehab the mapping was done.

How it was conducted

Design

Prospective case series (Level of Evidence IIb)

Participants

19 male athletes (age 28±9 yr) with an acute hamstring strain, presenting on average 6±6 days post injury

Intervention

Tenderness-to-palpation mapping of length, width, area, and location of the painful region on initial evaluation and remapped at rehab stages (52 mapping exams total)

Rehabilitation

All patients followed the same previously published lengthened-state hamstring rehab protocol; discharged on objective strength, symmetry, range-of-motion, and sport-specific criteria

Primary outcome

Days from initial evaluation to return to sport, analyzed against mapping indices by linear regression

What they found

• Average return to sport was 43±36 days (range 4 days to 17 weeks).
• Length of the tender area averaged 22±12% of posterior thigh length, width 26±11%, and area 3±2% of the posterior thigh.
• On initial evaluation, length of tenderness was the strongest predictor of return to sport (R=0.58, p<0.001), with correlation r=0.76, p<0.001.
• Area of tenderness was also related to return to sport (r=0.60, p<0.01; R=0.27, p=0.024).
• Age was related to return to sport (r=0.52, p<0.05).
• Width of tenderness was not predictive (r=0.08, p=0.75).
• Location of injury was not predictive: proximal-distal p=0.62 and medial-lateral p=0.64; time to return did not differ between proximal (39±33 days), central (38±39 days), or distal (59±42 days) injuries.
• Adding age to length of tenderness in multiple regression improved the prediction to R=0.73 (73% explained variance, p<0.001).
• Using all 52 mapping exams across rehab stages, the length relationship was essentially unchanged (R=0.61, p<0.001), and improved to R=0.69 with age added.
• Per the equation, 10% tenderness length predicts return in 17 days while 30% predicts 63 days.

Limitations

• All 19 subjects were male, so results may not apply to female athletes.
• The sample was small and heterogeneous, drawn from a variety of sports.
• All athletes followed one institution's rehab protocol, so predicted timelines may not generalize to other programs.
• Reliability of the palpation method was not established, and examiner pressure was not standardized, which may vary results between clinicians.

Why it matters

For patients

A simple hands-on exam early after a hamstring strain may give you a rough estimate of how many days until you can play again.

For clinicians

Measuring the length of tenderness as a percentage of thigh length is a quick, equipment-free prognostic tool, though it should be applied cautiously outside the studied protocol and population.

For readers

This is an early, small exploratory study suggesting palpation length predicts hamstring recovery time, and it needs validation in larger, more diverse samples before broad use.