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.
Quality of life improvements after medical interventions vary but for joint replacement are some of the highest of all medical procedures. Hip replacement has a long history but the 1960s saw its development into a reliable procedure, with modern developments making it a predictable and very successful treatment for hip osteoarthritis. It is used to manage a variety of complex hip conditions with excellent outcomes at fifteen years and beyond. Conservative treatment is always instituted initially but if the joint degeneration becomes severe then joint replacement is the remaining option.
The surgeon removes the osteoarthritic joint surfaces and replaces them with new components which are made of steel alloy and ultra high density polyethylene. The ball of the hip is replaced by a metal ball and stem and inserted into pressurized cement in the femoral canal. The plastic socket is pushed into the cement in the prepared socket to complete replacement of the two surfaces. Using the two materials, very slippery plastic and highly polished metal, ensures very low joint friction and a long functional life under load.
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.
A good gait pattern is important in restoring normal walking function, ranges of movement and muscle power and balance. Initial gait taught by physiotherapists is typically the “step to gait”, the walking aids moving forward first followed by the operated leg and then the unaffected leg steps up to the other. This is a slow but stable gait pattern and good for the initial stages. Patients progress quickly to the “step through gait” where the unaffected leg moves past the operated one, and eventually to an advanced gait where the crutches are moved forward at the same time as the operated leg. This pattern is very close to normal walking with a pair of crutches attached.
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.
