Hamstring Strains: Risk Factors and the Rehab Program with Zero Reinjuries

Most patients can return to relatively normal, non-athletic function with rest and restricted activity, so some may choose to reserve rehabilitation for certain circumstances. On the other hand, a poorly healed hamstring can limit future athletic activity as well as create postural imbalances that can lead to long-term spinal complaints.4 Given the potential to reduce high recurrence rates, it is also arguable that all hamstring strains should receive physiotherapy.

When withholding physiotherapy from certain patients, one strategy is to consider recurrence risk factors. Multiple systematic reviews and meta-analyses have established  hamstring strain recurrence risk factors.5-8 These include hamstring muscle weakness, quadriceps peak torque, thigh muscle imbalance, muscle flexibility, and age. Patients older than 22 prove more likely to have future hamstring injuries. 

A number of other factors have been cited but do not show correlations with hamstring strains in the systematic reviews. Qualities that are not risk factors include mechanism of injury, body mass index, height, hamstring length, dominant limb, pain provocation test, various measures of aerobic fitness, slump test, knee laxity, jumping ability, running speed, player exposure, and more. 

The strongest predictor of future hamstring injury is past hamstring injury. Patients with a past injury prove four times more likely to have a future injury. This supports the position that all patients with hamstring injuries should have physiotherapy.

 

Of course, not all physiotherapy programs are created equally, and many of the high recurrence rates reported are with formal rehabilitation programs. Encouraging new data suggests three important elements for optimal outcomes. Firstly, physiotherapy should begin as promptly as possible. Compared to patients seen in two days, patients with thigh or calf muscle strains seen nine days after injury took 33% longer to recover.7 Compared to usual rehabilitation programs, programs including trunk stabilisation accelerated return to play and reduced reinjury rates 79% (from 38% to 8%).10,11   

 

Even more encouraging is new data regarding eccentric hamstring strengthening. While most studies have found that injured legs tend to return to normal strength, more specific data finds that the peak strength occurs at earlier degrees of knee extension in the injured leg due to hamstring shortening. Comparative weakness of lengthened hamstrings correlates with injury recurrence.12 Three studies have evaluated eccentrically biased rehabilitation programs paying attention to strength at varying degrees of extension.13-15 These studies covered 108 patients combined, and measured zero reinjuries during follow-up periods ranging from one to three years. Additionally, recovery was accelerated. 

 

Data suggests that earlier referral to physiotherapy along with physiotherapy programs biased toward trunk stabilisation and eccentric loading have potential to greatly improve the usual experience with hamstring strains. 

References

 

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