Hamstring muscle injury

Findings

There is a history of an acute, non-traumatic injury during activities; with or without bruising tracking down to the back of the knee. There is a pain on stretching or resisted testing of the hamstring. The hamstring is best tested with an athlete lying prone so the leg can be tested against resistance, with a flexed knee and a straight knee. Resisted knee flexion and straight leg hip extension are painful. The hamstring lesion may be able to resist the examiner without pain, so the chair test can be utilized during the consultation to increase the loading on the hamstring. A chronic hamstring  injury with no bruising is more difficult to assess, because straight leg raising will be painful and Laseque's teste is  often ambigious, suggesting the possibility of reffered pain from the back. The slump test stretches the hamstring and invariably produces pain, but this pain is not releaved when an athlete raises his or her head during the slump test. Local tenderness over the ischeal tuberosity suggests possible avulsion or enthesitis, whereas local, palpable tenderness in the muscle is usually 6 cm off the origin or over the muscle lesion itself.

Cause 

A tear of sprain of the hamstring. The hamstring crosses two joints. Contraction of the hamstrings should extent the hip  and flex the knee. Occasionally the hip is flexed whilst the knee is flexed and this paradoxical movement is known as Lombard's paradox. This paradoxical movement can be overloaded during the change of cadence from the acceleration to the cruise phase of sprinting, running, or checking hard for a side step. Although the quadriceps/hamstring ratio is often quoted at 70% on isokinetic testing at 90 degrees per second, the balance in fact alters at faster speeds, depending onthe sport. Most become less quadriceps dominant, and indeed runners may become hamstring dominant. Some isokinetic tests in the prone position displayed a weakness in the hamstring that was not displayed when the hamstring was tested sitting. Tests also suggest that either the weak or the strong leg might be damaged, the strong leg presumably overworking to make up for the weak leg. Thus rehabilitation may have to be designed to train the weak, non-damaged muscle as well. EMG studies show that the hamstring decelerates the extending knee ready for impact(co-activation of the hamstring and quadriceps), so that downhill running or a sudden dip in the ground can upset this coordination, producing a tear. Thus a forced hurdles-style stretch can often provoke contraction of the hamstring, the very muscle one is stretching, and produces an avulsionof the hamstring origin at the ischium. A violent fall into hip flexion can avulse the hamstring origin.

Treatment

1)  RICE – Rest, Ice, Compression, Elevation

The first- line principle for treating an acute injury:

a)      Rest for 24-48 hours to prevent the clot spreading and an increase of inflammatory exudate. Mobilization too soon

 produces thicker scar tissue, which is not easily penetrated by fibroblasts and it may provoke continued bleeding.

b)      Ice will cool the periphery and shut down local vessels to decrease bleeding. Ice straight from the fridge may be

 less than 0 degrees and will produce an ice burn, unless separated from the skin by a cloth. Melting ice(wet ice) will be

 at 0 degrees and may be used as a bath for 20 minutes, but locally applied ice, for 5-10 minutes can have an effect. 

Reusable cold packs, which may be stored in the fridge, are available, as are some chemicals that freeze on mixing. Frozen

 packets of peas, which mould to the shape of the body, may prove most cost – effective. Care must be taken with ice placed

 around nerves, as they can suffer a cold-induced neuropraxia.

c)      Compression is again designed to reduce inflammatory exudates, and the spread of haemorrhage.

d)     Elevation prevents tracking of inflammatory products to the periphery, thus requiring less effort to return these

 products centrally.

2) Electrotherapeutic modalities to calm down inflammation. Massage techniques, such as effluage and frictions, to remove

fluid and any haematoma, plus cross-friction to encourage fibrocyte orientation.

3) Aspiration of any haemathoma, under ultrasound guidance, will fasten recovery.

4) Strecthing to prevent scar contraction.

5) Hamstring ladders - bottom and top( described in previous threads). Note that sometimes an injured leg can be stronger leg; therefore the weak, undamaged leg must be strengthened and trained.

6) Cortisone to the ischial tuberosity if the ischial bursa is inflamed, or the scar tissue is adhesive, followed by hamstring stretching and the rehabilitation ladders.

7) Epidural. These does appear to be some neural element causing persistent hamstring pain, in which case an epidural can be highly successful in curing this problem, especially if the slump test is just positive.

8) Surgical debridement of the tuberosity or resuture of any avulsion.

9) Early resuturing of avulsed hamstring origin ruptures.

10) Sacroiliac joint manipulation is thought to occasionally alter the relative position of the pelvis, and thus the tension of the hamstring origin from the ischial tuberosity. This therapy may be treating only reffered pain.

Sports

This injury can occur in most sports, and rehabilitation should be completed before attempting match competition. A previous hamstring injury predisposes to a further injury so rehabilitation must be satisfactorily completed. Hamstring training should be maintained even when the athlete is back to full competition.

This is a common injury. The primary postlateral disc is often misdiagnosed as a hamstring lesion. Hurdle-style stretch should not be forced. Ballistic stretching should also be used to to train up hamstring co-activation.

"Concise guide to sports injuries, 2^nd edition",Churchill Livingstone, Malcolm T.F. Read,  foreword by Bryan English