Friday, May 29, 2009

Physiotherapy After A Total Hip Replacement

By Jonathan Blood Smyth

Total hip replacement is one of the most common and effective orthopaedic operations and overall has one of the highest quality of life improvements of all medical interventions. Many, mostly elderly, people have a very good outcome with their hip replacement surgery but this can hide the potentially large numbers of sub-optimal outcomes where the person's function is limited by incomplete rehabilitation.

A typical picture is to have several years of disability and pain from an arthritic hip before coming to operation. This can have important knock on effects after operation as the tissues around the hip joint will have undergone changes which may not all be reversed by the replacement. With pain people limit the movements they put a joint through and this can lead to a gradual loss of range of joint motion, with the ligaments around the hip joint going through what is called adaptive shortening as they accommodate to the fact that the patient is not putting the joint through its full range of motion every day.

A second consequence of the pain and the stiffness is the development of weakness in the large muscles which serve the hip joint. The hip is a weight bearing joint involved in moving the bodyweight around and it generates very high forces in activity. To manage this the hip has the largest muscles in the body either attached to it or nearby to it. The hip extensors, including the glutei, are large powerful muscles which facilitate walking, running, stairs and getting up from a seated position. Loss of power in these muscles can be disabling and threaten independence.

The hip abductors, a smaller muscle group of the gluteal muscles, are important in controlling the side to side stability of the pelvic girdle in gait, with weakness of these muscles interfering with walking. Standing on one leg in walking we hold the opposite side of the pelvis up to avoid it dropping and make bringing through the moving leg more difficult. The hip abductor muscles do this and if weak we feel unstable in walking and tend to lurch towards the weak side, making us lean our trunk towards the other side to restore balance. This is described as a positive Trendelenberg sign.

The hip joint is exposed to abnormal forces in the Trendelenberg gait and the spine has to make repeated sideways movements each step to prevent overbalancing. In this kind of gait there is no strengthening of the hip abductor muscles so the abnormality remains. The pain and the weakness of the hip extensor muscles means that the person does not fully extend their leg behind them in each walking step, leading to a shortened and less efficient gait. Maintaining mobility becomes more and more of a challenge and can, in the absence of physiotherapy rehabilitation, lead to their hip replacement doing less well than hoped.

Patients typically have impaired balance and coordination even before they have their joint replacement operation, with some improvement occurring as the hip's function moves more towards normal after the joint has been replaced and the mechanical function of the hip is restored towards normal. Other impairments usually include the sense of joint position sense, an important ability the lack of which compromises balance and makes falling more likely.

Physiotherapy assessment of a hip problem covers many aspects of joint function which relate to the ability to perform routine daily functional activities. The pattern of gait will be noted and corrective work prescribed to improve the cycle of walking as an abnormal gait can be habitual and easily improved. Knee, hip and spinal ranges of motion will be assessed to ascertain whether stiffness or any limitation is interfering with normal movement.

Excessive range is not encouraged in hip replacements due to the risk of dislocation. Next the muscle power in all the surrounding muscles will be tested and then the person's balance reactions and joint position sense. Once the assessment is complete the physiotherapist will give the patient a programme including joint mobility, strengthening, and balance and gait correction. Many with hip arthroplasty do not reach their best potential due to a lack of rehabilitation care after the operation. - 14130

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