Hamstring tears are a widespread sporting hazard, reported in sports as diverse as athletics, football, Australian rules football, cricket, rugby, hurling, dancing, water skiing and judo. They are often serious, causing long rehabilitation times and a increased susceptibility to re-injury. Persistent symptoms and slow healing make hamstring tears a frustrating injury.
The prevalence of hamstring tears (defined as ‘preventing player participation in a match’) has been measured at between 11% and 16% in studies of football, Australian rules and cricket (1, 2, 3, 4, 5) . About six players per squad will pick up a hamstring injury each season in professional soccer and Australian Rules football (1, 5).
An acute strain to the hamstring muscles may result in a spectrum of injuries ranging from delayed onset muscle soreness and partial strain to complete muscle rupture. Avulsion of the ischial tuberosity (where the bone is pulled off while the muscle attachment remains intact) occurs occasionally in young athletes (6, 7). Complete rupture of the top end of the hamstring complex – the focus of this article – is a relatively unusual injury, and there are few reports in the sports literature.
Injury can cause a player to miss, on average, three matches or three weeks of play (1, 5).
Anatomy and function
The word ‘hamstring’ comes from ham (back of the knee) and string (tendon); the hamstring group is comprised of the three muscles that together span the posterior compartment of the thigh: semitendinosus, semimembranosus and biceps femoris. At their top end, the muscles attach to the ischial tuberosity of the pelvic bone and the femur (thigh bone). At their far point, they attach to the outer side of tibia and fibula (the leg bones).
The hamstring muscles, with their two-joint attachments, serve the unique function of flexing the leg upon the thigh; and contribute to the hip extensor function of the gluteus maximus muscle.
Hamstring injuries in sport usually happen as a result of rapid acceleration or deceleration while running or jumping. The main modifiable risk factors include:
* inadequate warm-up lmuscle fatigue
* muscle tightness
* imbalance of muscular strength with low hamstring to quadriceps ratio
* previous injury.
The risk of injury is reported to be higher among black and aboriginal people, and increases with age (1, 8, 9).
Symptoms and signs
The most common symptom of upper hamstring tear is pain in the back of the thigh or buttock. Other symptoms include swelling and bruising (ecchymosis) of the rear thigh, local tenderness, asymmetry and a slipping or bunching of the avulsed muscle belly down the thigh. Weakness and visible defects with active and resisted knee flexion may confirm a complete hamstring tear at the upper attachment.
After a hamstring injury, diagnosis is often delayed. Therapists should be prepared to seek early ultrasound imaging to verify suspected tears. MRI can also identify which muscle has been injured and the amount of tendon retraction that has occurred(10). Sciatic nerve symptoms, such as numbness or muscle weakness should also be investigated. These are often related to inflammation and scarring around the nerve, because of its close proximity to the injured muscle groups. Note that pain referred from the lumbar spine, sciatic nerve or gluteal and piriformis muscles may mimic hamstring strains (8).
The initial management of hamstring injuries involves rest, analgesia and ice packs. But where you suspect a complete upperattachment tear, a conservative approach is not advised. In these cases, non-operative management is associated with a delay in return to sports and long-term functional impairment. It is currently thought far better to seek an early diagnosis and acute surgical repair to reattach the torn tendons (11, 12, 13, 14).
Other reasons to consider operative management of an injury would be where there is a partial hamstring origin tear, sciatic nerve symptoms or chronic tears with functional impairment.
Good results from operative re-attachment, with a successful return to sport, have been reported. This is also our experience of having performed eight complete upper-end hamstring tear repairs in athletes during the last five years. The average time from injury to surgery was five weeks, with the range (one to 14 weeks) reflecting the tendency for delayed diagnosis. A return to full activity was achieved at an average of 25 weeks (the range was 18 to 65 weeks).
Rehab and return to sports
After their operation, the patient will be braced for eight weeks, to stabilise the hip in extension and the knee in 90 degrees of flexion. They will progress to specialist physiotherapy and a supervised rehabilitation programme lasting six months. The physiotherapy mainly focuses on stretching and strengthening of the hamstring muscles. Most patients regain full range of motion at 14 to 16 weeks of recovery.
Re-injury to hamstring tears may be a result of the risk factors associated with the initial damage (15). Tears heal by scarring; ineffective treatment results in an accumulation of scars and adhesions, predisposing the athlete to re-injury. Previously injured muscle is more susceptible to eccentric loading damage (16) . The re-injury rate after surgical repair of torn upperattachment hamstring origin is not known.
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5.Orchard, J, Seward, H, (2003) AFLMOA. AFL Injury Report 2003(online). Available from URL: http://injuryupdate.com.au/images/research/AFL 2003InjuryReport.pdf, 2003
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14. Thomsen, NO, Jensen, TT (1999) ‘Late Repair of Rupture of the Hamstring Tendons from the Ischial Tuberosity – A Case Report’. Acta Orthop Scand. 70:89-91.
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