Hamstring Injury
The hamstrings are a muscle group which are situated at the back of the thighs and are commonly involved in injury from vigorous activities and sports. Hamstring injuries are more commonly involved in areas of the muscle which are closer to the buttock and on the outside of the back of the thigh. There are three muscles in the hamstring group and they do not have common names, being termed semimembranosus, semitendinosus and biceps femoris. The latter is the muscle most commonly involved in typical sporting injuries.
Hamstring injuries are classified for ease of diagnosis and treatment into various grades of severity. The least serious injury with a number of damaged muscle fibres is a grade 1 injury, rated as a mild muscle strain. More serious involves a larger number of muscle fibres being damaged and a reduction of muscle strength which is obvious on testing and this is a grade 2 injury. In the most serious or grade 3 injury there is a rupture right through the substance of the tendon and muscle. Most injuries are located at the muscle and tendon junction and high up near the buttock, although the biceps femoris has a very long junction, most of its length.
The ischial tuberosity (the bones we sit on or the “bones in the buttock”) is the originating point for most of the hamstring tendons. An avulsion fracture may occur at this point where a sudden, large range of motion occurs without warning and pulls off the tendon from the bony connection, an affliction most commonly seen in people who water ski. Younger people have larger numbers of such injuries as they are more active in sport and participating in risky activities such as contact sports, field sports, sprinting, rugby and football.
The hamstrings start at the ischial tuberosity in the buttock, run down the back of the thigh and insert into varying places on the tibia or fibula. When these muscles are contracting and lengthening at the same time (eccentric contraction) such as in track events and rugby, there can be a high risk of injury. Direct muscle blows can result in contusions to the tissues while water skiers are more prone to avulsion injuries as they fall because they undergo rapid hip flexion with their knees straight. Onset of a hamstring strain is typically sudden and often when the person is moving quickly, with an audible pop in the muscle often reported.
Pain is felt in the back of the thigh immediately and the injury is often either early in the activity (not yet warmed up) or late in the activity where tiredness may be a factor. General movements and functional activities such as stair climbing may be painful provided the injury is not too severe. There may be little to see in the posterior thigh of these patients but testing the ability to bend the knee against resistance may elicit a painful response. If one of the hamstring muscles is ruptured it may contract up into a ball on testing and the examiner will notice the reduced strength.
The likelihood of suffering from an injury to the hamstring is thought to be related to factors such as tiredness, inadequate warm up, flexibility restrictions or if the strength ratio between the hamstrings and the quadriceps is incorrect. Having previously incurred a hamstring injury is enough to raise the risk of having another one. How an injury will be treated depends entirely on its severity with one end of the spectrum seeing the physio progress the patient speedily on to strength work and at the other end of the spectrum some injuries require the intervention of a surgeon.
Physiotherapy for a moderate level injury initially addresses the reduction of local swelling and inflammation and control of the pain which is often significant. The physio will use the PRICE guidelines for treatment: Protection of the injured tissues is vital at first which can include crutch use or braces; Rest is essential to a degree to allow tissue healing to proceed; Ice application for up to 20 minutes reduces pain and inflammation; Compression can be effected by wrapping elasticated bandages around the limb; Elevation is not simple due to the area of the damage and that the patient may prefer a bent knee.
Jonathan Blood Smyth is the Superintendent of Physiotherapists at an NHS hospital in the South-West of the UK. He writes articles about back pain, neck pain, and injury management. If you are looking for Sheffield Physiotherapist visit his website.