The hips are ball and socket joints between the legs and the pelvic part of the trunk. The joint consists of a rounded ball (the femoral head) which fits into the reciprocally rounded socket (the acetabulum) which is quite deep and envelops most of the head. It is a large joint, the surfaces mirror each other well and it is stable. The articular cartilage of the hip is a shiny, friction-free material which aids the easy movement of the joint even under load, and is vital to normal functioning of the hip. The cartilage is thickest where weight bearing occurs most commonly, at the uppermost point of the head and the socket.

Surrounding the head, socket and neck is the capsule of the hip joint which runs from the lip of the socket down over the head and neck to the base of the neck. It is a fibrous bag lined by synovial membrane which secretes the lubricating and nutritional fluid for the cartilage, and is strengthened by denser bands of tissue, the major hip ligaments. The hip is designed so that the femur can fit into the socket in the pelvis at an appropriate angle for weight bearing and exerting mechanical forces. The femur comes up to the hip area and then the neck turns inwards at an angle of 125 degrees to access the pelvic socket.

Inside the hip the bony anatomy of the supporting struts or trabeculae are also mechanically aligned along the lines of most force, responding to the requirements of bodily motion and bearing weight. The densest areas reinforce the parts suffering the highest stresses. If the hip copes with these stresses by developing strengthened areas it also has areas of less strength which can become relevant in older people as they fall and suffer fractured necks of femur across these areas. As the number of older people dying after this fracture is relatively high, this matter is of concern.

The hip is designed to perform locomotion of the body and to stand and manage the body weight through the legs. To perform these actions the hip joints have very strong muscles to stabilise them and move them and the body in some cases quickly and with force. The hip abductors, adductors and gluteal muscles are all major stabilisers and movers of the joint. The abductors play a large part in the sideways stability of the pelvis and the gluteals, the body’s most powerful muscles, move the body weight around.

When performing activities such as climbing stairs, jumping or running, the joint surfaces of the hip are exposed to much higher mechanical stresses than just the body weight. To allow for this the most exposed areas to the weight are covered by the thickest cartilage. The underlying bone and the synovial membrane fluid are responsible for nutrition to the cartilage but this is not a very strong process. Cartilage turnover is slow with some forming at the base as the upper layers get damaged and are lost.

The synovial fluid is secreted in small amounts by the synovial membrane lining the capsule of all synovial joints. There are only small amounts of fluid involved but it has several possible functions: nutrition and lubrication of the joint, removal of small particles of cartilage wear to prevent a rough debris collecting and an evening out of stressful loads through the joint. The synovial membrane will respond if the joint is suddenly worked hard by increasing fluid secretion to enhance the protective qualities it brings to the joint under load.

Any disturbance in the available movements of the hip will have consequences on its most important function, gait. An even stride length and balanced gait pattern is essential for normal daily function and to the health of the hip joints themselves. We have a typical and restricted pattern of joint movement when we walk but the movement which often becomes limited first is extension, the ability to take the leg behind as the other leg strides forward. At around 20 degrees there is much less hip extension that hip flexion, the ability to take the thigh towards the chest, which is about 130 degrees.

Jonathan Blood Smyth is the Superintendent of Physiotherapists at an NHS hospital in the South-West of the UK. He writes articles about back pain, neck pain, and injury management. If you are looking for physiotherapists in Cambridge visit his website.

categories: Back pain, injury management, sciatica, Piriformis Syndrome, pain management,sciatica, back injury, back pain relief, Frozen Shoulder,Alternative medicine, physiotherapists, physiotherapy,Health

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.

If there is a sudden damaging event to the hip such as a strain, jar or a fall the joint can deteriorate rapidly and become much more painful very quickly. This occurs less often however than a gradual onset of pain and stiffness over a longer period of time. A trivial occurrence can set off a joint worsening, beginning with spasm of the local muscles and a loss of the typical range of extension useful in gait. Full extension is the position in which the hip is most tightly fitting and all the surrounding tissues are at their tensest, a position avoided in painful conditions.

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.

The major weight bearing joints of the knee and hip are mostly affected by osteoarthritic changes, osteoarthritis being the most common degenerative joint condition in the world. Many factors contribute to the incidence and severity of arthritis, with a family history being important to some degree. Osteoarthritis becomes much more prevalent with increasing age and is almost universal in some joints in older people. As the arthritis worsens the joint can gradually lose movement as the capsule tightens, with a slow healing due to the lack of good 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.

In the initial stages the x-rays will indicate little of value and the x-ray findings often are not easily correlated with the patient’s disability or pain. As the osteoarthritis worsens joint changes become gradually more apparent such as loss of some of the joint space from cartilage thinning. If severe the head of the femur may become misshapen and osteophytes (bony outgrowths) may occur at the joint margins. In severe arthritis movement and weight bearing may be accompanied by obvious shuddering and grating.

There is a particular order in which the restrictions of joint movement develop in the hip joint. The first movement lost is extension, followed by moving the hip outwards (abduction) and finally of the ability to turn the thigh inwards (internal rotation). On examination by a physiotherapist the hip will present turned outwards, close to the midline as moving it away is difficult and held in slight flexion due to the loss of extension. As the leg cannot be extended in walking and the leg is shorter than the other side each step of gait necessitates a trunk twist and a small toe raise to allow for the abnormalities.

Jonathan Blood Smyth is the Superintendent of Physiotherapists at an NHS hospital in the South-West of the UK. He writes articles about back pain, neck pain, and injury management. If you are looking for physiotherapists in bradford visit his website.

categories: Back pain,injury management,sciatica,Piriformis Syndrome,pain management,sciatica,back injury,back pain relief,Frozen Shoulder,Alternative medicine,physiotherapists,physiotherapy,Health,physical fitness