REHABILITATION FOCUS REHABILITATION FOR HAMSTRING MUSCLE STRAINS

By Lee Herrington, MCSP

Injury to the hamstring muscle group represents a signifi- cant proportion of the total number of lower limb musculo- tendinous injuries occurring with sports participation. In football the lower limb is the site of 87% of all injuries, and the thigh is the most commonly affected site claiming 23% of all lower limb injuries (1). The frequency of these injuries has often been related to the anatomy and biomechanical function of the hamstring muscle group. As the hamstrings are ‘two-joint’ muscles, that is they cross two joints and are able to act on both joints simultaneously, they are at greater risk of excessive lengthening (tensile loading) than single joint muscles.

This article presents a rehabilitation programme for a hypo- thetical footballer who has sustained a minor (grade 1) tear of their biceps femoris muscle at the musculo-tendinous junction. The footballer has presented for treatment in the acute stage (within 48 hours of injury) and on examination the patient has pain and decreased strength on isometric testing and a reduced straight leg raise. All differential diag- nosis testing is negative (see previous article).

Injury to the hamstring muscles occurs most frequently during the late swing phase of the running (sprinting) gait, when the muscle is being actively lengthened at both the hip and knee and is attempting to contract eccentrically to decelerate this imposed load. If this load is greater than the eccentric strength of the mus- cle at that time, then the applied force will tear muscle fibres and

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surrounding connective tissue. Partial tears of the muscle occur where not all of the available fibres have been torn, that is, the muscle is not totally ruptured.

Anatomy Biceps femoris, which originates from the ischial tuberosity of the pelvis (see Fig.1 p7) and the linae aspera of the posterior aspect of the femur, is a classic two-joint muscle able to act at both the hip and knee as it shortens with contraction. The primary action of this muscle is knee flexion and hip extension, but because of its rela- tionship to the joint axis of the hip and knee it also brings about hip abduction and lateral rotation of both the thigh and to a greater extent the tibia. These secondary actions of the muscles must be taken into account when both strengthening and length- ening the muscle, in order for effective rehabilitation to take place.

Rehabilitation programme The immediate goal of treatment is to minimise further tissue dam- age, this is done by reducing the negative effects of the inflamma- tory process, that is decreasing swelling, reducing pain and improv- ing the quality of fibrous scar tissue being laid down and reducing secondary tissue hypoxia. Initial treatment is through the PRICE protocol; protection, rest, ice, compression and elevation (2) to reduce the inflammatory reaction caused by the injury. At this stage non-steroidal anti-inflammatory drugs may also prove useful.

After the initial 48-72 hours of the inflammatory phase of healing the fibroblastic phase begins, here the precursor to collagen is laid down to begin the process of scar formation. At this stage ultra- sound, gentle transverse frictions and specific soft tissue mobilisa- tion (3) may prove useful.