Osteoarthritis (OA) is the commonest joint degeneration condition in the world, resulting in huge amounts of pain and suffering, work loss, expense and disability. Ageing of western developed populations, soon to be followed by some developing countries such as China, will place an increasing burden on medical services as the occurrence of OA rises steadily with age. There will be an increasing need to provide medical and physiotherapy treatment for OA over the next 50 years and for many thousands of people this will involve joint replacement.

Of all medical interventions, joint replacement has one of the highest increases in quality of life, transforming a person’s mobility, outlook and independence. Developed in the 1960s to a level where mass treatment was feasible, total hip replacement has matured into a predictable and successful treatment for OA with very good results stretching to 15 years and beyond. Conservative treatments are the mainstay of management of OA but once it becomes severe hip replacement is the only option.

Total hip replacement involves removal of the arthritic joint surfaces and their replacement with metal and plastic components. The top of the femur, the ball of the hip joint, is removed and the socket is reamed out to make it bigger to accept the new part. Cement is pressurized into the bony areas and a steel alloy femoral component with a ball and stem is inserted down the femur and a plastic cup of ultra high density polyethylene into the socket. The metal-plastic interface allows very low friction and wear, ensuring a long life for the joint.

On return from operation the physiotherapist will check the patient’s operative record, medical observations and assess the patient. Initial physio treatment consists of checking respiratory status and the muscle power and feeling in the legs to exclude nerve injury. Exercises are given to restore normal movement although an epidural can cause loss of movement in the legs and delay progress. The physiotherapist will then mobilise the patient with an assistant, taking care of the hip precautions, stand them up and walk them a short distance with elbow crutches or a frame.

Hip flexion, knee extension, buttock and calf exercises are practiced whilst in bed to reactivate the leg muscles and pump the blood around the limb. Routine analgesia is very useful as reduced pain allows easier exercising and mobilising. Patients can now go to the toilet, wash and dress and walk about the ward with a helper if needed, at least three times a day to get their confidence. When sitting, correct height chairs are vital and patients should avoid having their feet up on a stool.

After hip replacement patients require instruction and correction to achieve a normal walking pattern, develop muscular power and improved function. Physiotherapists teach the appropriate gait at the time, often starting with “step to” where the patient moves the walking aid, steps the operated leg forwards and steps up to it with the other leg, a stable and safe pattern. Progression is to ‘step through” where the unaffected leg steps beyond the other in an approximation of a normal walking pattern. Patients often progress naturally then to a gait where they move both the crutches and the affected leg forward at the same time and start to walk in a fully natural pattern.

Six weeks or so after the operation the patient will have a good gait, have reasonable muscle power and be able to do most functional activities such as a walk, climb stairs and ride in a car. They may then move on to a stick if stability or balance is difficult or the person is very old. Patients can now return to normal activities but need to maintain the hip precautions: Avoid crossing the legs in sitting. Don’t stand on the affected leg and rotate. Don’t flex the hip suddenly or above 90 degrees, such as by sitting in a low chair, sitting down too fast, crouching or leaning forward quickly to the feet. If an infection develops, for example chest, teeth or bladder, then the doctor should be informed as infections can settle in an artificial joint.