Physiotherapy After A Total Hip Replacement
Total hip replacement has matured into a routine operation for the relief of hip pain and disability due to hip arthritis, giving some of the greatest quality of life increases of all medical procedures. Typically performed in older people, many get a good result from their hip replacement surgery but many do not reach their greatest potential due to lack of follow up rehabilitation in the post-operative period.
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 Trendelenberg gait is abnormal and increases the forces through the hip and forces the spine laterally each step to maintain balance. The abductor muscles fail to strengthen and an abnormal gait develops. The gait can be shortened and slowed also if the person loses the ability to extend their hips adequately and the hip extensor muscles are not strong enough for sufficient push off. A combination of muscle weakness and joint restriction can make mobility more challenging than it should be and ensure a less than optimal outcome for the patient, easily remedied by some physiotherapy rehabilitation.
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 rehabilitation consists of looking at a person's hip function which impact on their functional ability to get about and to do normal daily activities. Initially the physiotherapist will note the patient's gait and correct any abnormalities to bring the gait towards a more normal pattern. An abnormal pattern can just be a habit so needs correcting. The physiotherapist will also assess the joint ranges of motion in the hip, knee and perhaps spine to investigate whether any functional limitations are due to stiffness.
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.