Alex Ram

The effect on the function of the hip joint of a difference in the length of the legs has been mentioned previously in an article in this series. The longer of the two legs will attempt to keep the head level by flexing slightly at the hip and knee, leading to a lack of movement into extension of the hip as we walk. Rotation of the hip and pelvis is required to achieve a more normal gait pattern if extension is not fully achievable. This may be a small change in joint movement, but on repetition thousands of times per day this can set up difficulties in joint movement and over time a painful joint condition.A sudden injuring event such as a sprain, fall or jar can cause a sudden worsening of the condition of the hip, with much increased pain and reduction in movement. It is however more likely that the hip will become gradually more troublesome with time. A minor mechanical upset can set off an exacerbation of the joint with a loss of the normal range of motion into extension and some muscle spasm. In extension the hip is in what is called full pack, where the surrounding tissues are tightest and the joint is most closely fitting, typically avoided by anyone with a painful hip.A typical reaction to a painful hip is the development of a limp, a common finding in hip and knee pain problems. Whilst possible to eradicate a limp, once practiced for a while, is very difficult. A limp changes the mechanical stresses through the hip radically, alters the muscle function to different angles and allows the joint to restrict its ranges of motion. This can encourage the hip capsule to tighten up further and perpetuate the cycle. This is why physiotherapists encourage people with hip problems to perform as normal a gait as possible.Osteoarthritis is the commonest joint problem suffered by the large weight bearing joints such as the hip and the knee. Osteoarthritis is a degenerative joint condition with many factors important in its development, with genetic factors such as family history of relevance. The incidence of osteoarthritis rises rapidly with age and most older people have a least a few joints affected. As the process proceeds, the joint may tighten, lose further range of movement and heal slowly due to its relatively poor blood supply.Gradual destruction of the cartilaginous joint lining continues, with some muscle spasm and increasing limp. At some point some arthritic joints deteriorate quickly, perhaps after a trivial traumatic event, and the exact reason for this is not clear, but increased pain and consequent increased muscle spasm may be responsible. Typically hip pain is felt in the lower buttock, the side of the hip, the groin and the front of the thigh. Some patients go to the doctor thinking that they have a thigh or knee problem and end up being diagnosed with hip arthritis.Initial x-rays of the hip will often show little of note, the findings on x-ray may not correlate well with the levels of pain, and disability a patient is feeling. As the osteoarthritis proceeds the changes on imaging become more obvious such as a narrowing of the apparent space between the bones due to thinning of cartilage. The femoral head may become abnormally shaped and bony outgrowths develop as the joint suffers damage and attempts repair. Severe degeneration results in an unpleasant audible grating and shuddering in the joint on weight bearing.The losses of joint movement in the hip occur in a characteristic order, with extension being lost first, followed by abduction, the ability to move the hip out to the side and finally of internal rotation of the joint. On examination of a hip with an osteoarthritic joint the hip will be held forwards and lack extension, the leg will be rotated outwards and can be held close to the other leg as it cannot easily be moved away. The lack of extension and shortening of the leg due to the arthritis can force the trunk to twist in gait and the person to go up on their toes slightly to compensate for the shortening.Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapists, physiotherapy, Physiotherapists in Bournemouth, back pain, orthopaedic conditions, neck pain and injury management. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.