The Pelvic Girdle (part 2)

Resident physiotherapist Joseph O’Connor tells us a little more about the hip joint and common causes of hip pain.

The Hip is a ball and socket joint consisting of the the acetabulum (socket) which is formed from the pelvis, and the head of the Femur (ball). The primary purpose of the joint being to bear the weight of the upper body and be the ‘bridge’ that transfers this weight to the Femur (thighbone). The Hip is different from the other main ball and socket joint of the body (the shoulder) due to it’s deep socket and strong ligaments surrounding the joint, giving it much more stability but less flexibility. When clinically assessing the Hip and its surrounding structures it is important to remember its primary purpose (the transfer of weight between the upper and lower body) and therefore look at how well it copes with this task.

Looking at how the Hip copes with the transfer of weight onto one leg during the stance phase of walking and how the upper body is held on the leg during standing can both reveal functional problems with the hip. ‘Normally’ when all of the weight is on one leg the upper body should remain ‘in line’ with the leg. Shifting your weight onto your right leg for instance, should result in the right shoulder, hip, knee and foot remaining in a straight line. We look for changes in this line that can indicate problems within the hip joint itself or with the neuromuscular system not controlling the position of the joints sufficiently.

Common problems:

Clinically we see two relatively common problems with the Hip joint that are markedly different in their cause and also their treatment.
Differential diagnosis is extremely important as misdiagnosis can lead to a treatment approach that at least will not improve symptoms and at worse exacerbate them significantly.

Degenerative change within the hip joint (Osteoarthritic Hip).

‘Wear and Tear’ to the articular cartilage that lines the Hip is a normal part of the ageing process. However, some people undergo much greater degrees of this ‘degenerative change’ than others. Patients normally describe a gradual onset of pain in the ‘groin’ that is worse with walking and difficulty getting their shoes and socks on. Classic signs of this condition are shifting the weight onto the better leg whilst standing, and a big shift in the upper body when putting weight on the affected leg whilst walking ( ‘throwing the torso over to the right on right stance for instance). This is the body’s way of trying to ‘offload’ where weight is taken throughout the worn ball and socket joint.

As well as pain, symptoms often include stiffness, especially with functional activities like crossing legs to put socks on or sitting down or standing up from a low chair. Plain x-ray is still the ‘gold standard’ of determining pathology in the hip joint. In a healthy hip, there appears to be a space between the ball and socket. This is because the articular cartilage that fills this space not dense enough to show on x-ray. A lack of ‘space’ indicates complete breakdown of the articular cartilage leaving ‘bone on bone’. This is a structural problem- essentially the structure of the hip joint has changed and this is irreversible. Controlling how the hip is used can help but ultimately this type of problem is best dealt with surgically (Hip Replacement) when appropriate.

Hip Impingement:

The ball and socket components of the hip are designed to take load in a very specific position.
The gluteal muscles around the hip should work to control the position of the trunk and pelvis at a right angle to the leg. In cases where the gluteal muscles fail to control this position the angle between the pelvis and thighbone is altered, effectively changing which part of the ball and socket are under load which can cause pain via ‘stress/strain to tissues in and outside of the hip.

Trendelenburg sign:

Patients that present with this problem often complain of groin pain with weight bearing, tightness in the inner thigh muscles and problems with running, kicking etc. This is a functional problem, as opposed to a structural one as the structure of the joint is healthy but is painful as it is under stress due to a faulty movement pattern or lack of control. Improving the hip control through specific exercise and movement re-education is the treatment of choice for these types of problems. As previously stated- a correct diagnosis to establish the cause of pain or dysfunction is vital before any intervention to ensure the correct approach is implemented.