The Human Hip - Part Three
In the last article we touched on the importance of leg length discrepancy on the function of the hip and the back. The longer leg will tend to bend slightly at the hip and knee to even up the level of the head and the eyes, meaning that the hip does not go into full extension at the back of every step. If the hip is unable to move into extension the back is forced to rotate to some degree to accomplish the range of motion required for walking. When this abnormal movement is repeated many thousands of times per day this can set up joint restriction, functional difficulties and painful problems.
The hip can give problems and deteriorate into a severely painful joint very quickly after a traumatic event such as a fall, strain or jar. However, this is less common on average as hip problems usually come on slowly over a long period. A small event can set off a painful process which starts with some muscle spasm and a reduction in the extension range typically used in walking. The hip joint is at its tightest and most pressured when it is put into extension, and when we have a painful joint we avoid this kind of joint position in order to avoid pain.
A painful hip or other lower limb joint such as a knee is often accompanied by the development of a limp, which is difficult to correct or get rid of when it has been entrenched over some period. The mechanical forces which are transmitted through the hip are significantly altered by a limp, and it changes the actions of the muscles and allows movement restrictions to develop. A steady tightening of the joint capsule can develop and cause loss of hip range of movement. On assessment and treatment of a hip problem a physiotherapist will always correct gait.
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.
The steady loss of the articular surface of the hip goes on with an increased limp and consequent spasm of the hip muscles. There can be a rapid deterioration of an arthritic joint without much of a mechanical insult and it is not understood exactly why, but elevated levels of muscle spasm and pain may contribute. Pain from a hip joint refers to the anterior thigh region, the groin, the side of the hip or the lower buttock. Patients may attend a medical consultation with what they expect is a leg or knee condition and are surprised with a diagnosis of an arthritic hip.
Little useful information may come from x-rays of the hip in the early stages of osteoarthritis and the patients disability or pain is not easily connected with x-ray findings overall. A worsening joint will show clear x-ray changes such as narrowing of the joint space caused by loss of thickness of the articular cartilage. Abnormal shaping of the femoral head and the formation of marginal joint bone outgrowths called osteophytes will occur in severe cases. On bearing weight or movement a severely osteoarthritic joint will shudder and grate audibly.
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 Coventry, 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.