The hip

The hip is rarely involved in extrinsic trauma but is commonly affected by intrinsic trauma (fractured neck of femur) and by chronic conditions (osteoarthritis). The examination of the joint is made more difficult by the fact that it is covered by muscles. It is also likely to present with pain referred to the knee, and can be the site of pain referred from the spine.

Look

Limp

Watch the patient walk, and look for a limp. The limp of a stiff hip is difficult to spot as the patient rocks their pelvis with the femur on the affected side, but fixed flexion defor­mity is common and leads to the patient walking with a characteristic stooped gait.

Skin

The scars from surgery on the hip are usually on the lateral side of the hip.

Soft tissue

  Gluteal wasting can occur if the superior gluteal nerve was damaged after hip surgery, but beware of confusing gluteal

wasting with loss of lumbar lordosis caused by back prob­lems. The tilt of the pelvis may make it look as if there is bilateral gluteal wasting.

Bone

There is little to see because the hip is so deeply buried, but a limp may give a clue to underlying bony deformity.

Feel

Skin

As the joint is so deeply buried the only item that needs checking is distal sensation. Damage to the femoral nerve produces numbness over the front of the thigh. Damage to the sciatic nerve will produce numbness in the lower leg.

Soft tissues

Peripheral pulses can, again, be tested in the foot.

Bone

The hip can be palpated anteriorly in the groin beneath the femoral pulse, but the hip is deep and difficult to feel. Tenderness on the lateral side of the hip arises from the greater trochanter or is referred from the spine. Pain posteriorly is usually the sciatic nerve or, once again, has been referred from the spine.

Leg length discrepancy

Leg length discrepancy can be caused by bones in the two limbs being of unequal length, such as might occur after a fracture. It can also be caused by deformity such as a fixed flexion deformity of the hip. Leg length discrepancy caused solely by short bones is known by convention as ‘true’ leg length discrepancy. That caused by joint deformity is known as ‘apparent’ shortening. Most leg length discrepancy is caused by a mixture of the two.

True leg length discrepancy. It is usual to measure the ‘true’ leg length discrepancy first by putting both legs as straight as possible, and then measuring the leg which cannot be put straight. The other leg is then put into an identical position, so that the deformity has no effect on leg length discrepancy. If the end of the tape measure is held firmly between the pulp of the thumb and the side of the index finger the tip of the thumb can be used to trace the inguinal ligament upwards until it catches in the notch immediately below the anterior superior iliac crest. A similar manoeuvre can be used at the lower end of the leg. The tip of the examiner’s other thumb is traced up the calcaneus, until it jams in the notch immediately below the medial malleolus. The measure is repeated on the other limb which is first put in the identical position.

In order to decide which bone(s) are responsible for the shortening, the patient should lie supine and the knees should be bent up to a right angle. The examiner should then look at the knees from the side. If the

femur on the short side lies lower then the shortening is below the knee. If the tibia lies further back then the shortening lies above the knee. If the shortening is above the knee then palpation of the greater trochanters will reveal whether the shortening is in the femoral neck or in the femoral shaft. If the shortening is below the knee then palpation of the medial and lateral malleolus will reveal whether the shortening is above or below the ankle.

Apparent leg length discrepancy. Apparent leg discrepancy is that caused by joint deformity and is best calculated from the difference in true leg length, as measured above, and the difference in leg length when both legs are put as straight as possible.

 Leg length discrepancy is very difficult to measure accurately using clinical methods, but can be measured very precisely, when necessary, using X-rays with grids superimposed. An alternative method clinically is to give the patient raised blocks to walk over. The height of the blocks is raised under the sole of the shorter leg until the patient feels that the short leg is now too long. Reduction of the height by 5 mm usually produces a measure which can be used as a shoe raise to correct leg length inequality. Discrepancies of 1 cm or less can usually be hidden inside the shoe. Raises of up to 2—3 cm can be put on the heel only, so keeping the shoe light. Raises of more than this usually require a raise of the sole and the heel.

Move

Active and passive

In the hip active and passive movements are measured together in the modified Thomas’s test, which will be described below.

Modified Thomas’s test. The patient bends up both their knees and hips actively, rolling themselves into a ball. The examiner can then carefully (watching the patient’s face) push the hips into further flexion (passive flexion). The flex-ion of the two hips can now be checked and compared. The patient is now asked to hold the affected hip flexed by hold­ing their shin in their hands. This fixes the pelvis in full flexion. The other leg is now carefully extended as far as comfortable and a note made of the angle that the femur makes to the couch in full extension. The normal leg is now flexed back up again as far as possible, and held there by the patient. The abnormal hip is now allowed to extend (carefully watching the patient’s face) until it too will extend no further (Fig. 20.17). Again, the angle that the femur makes with the couch is noted and compared with the recording made on the other side. Both legs are now lowered on to the bed and a note is made of the range of flexion and extension of both hips, noting that the examination was performed with the pelvis in full flexion.

Abduction. Lay your forearm across the patient’s pelvis with the tips of your fingers resting on one anterior superior iliac spine and your forearm resting on the other one nearer   to you. Abduct first one hip and note the angle when you feel the pelvis starting to move under your hands. Return that leg to its original position and repeat the manoeuvre with the other leg. Abduction. Still leaving one hip abducted, adduct the other hip across until the pelvis starts to move. Put that hip back in abduction and adduct the other hip, noting the range of move­ment of abduction and adduction on both sides (Fig. 20.18). Rotation. Rotation of the hip will always be limited in extremes of extension and flexion, as the capsule of the hip is already tight. It is therefore important to test the range of movement of the hip in the mid-range with the thigh flexed at 450• If the knee is flexed to 900 the tibia can be used as a lever and a protractor. Watch the patient’s face, and test internal and external rotation, comparing the two sides. Note that when the foot comes across the body you are testing external rotation, and when the foot comes out to the side you are testing internal rotation (Fig. 20.19).

Stability

The Trendelenburg test. This is a test of stability of the hip joint or of weakness of the gluteal muscles, such that the patient has great difficulty taking all of their weight on the affected leg. The most sensitive way of performing this test is to ask the patient to stand on both legs facing you, and to place their hands palm downwards on your hands held palm upwards. The patient is asked first to stand on their healthy leg, then repeat the manoeuvre on the affected leg. If the test is positive the examiner will feel a firm push downwards from the patient’s hand on the affected side as the patient tries to transfer their weight on to the affected limb (Fig. 20.20).

Tests for referred pain

Pain in the hip can be referred down from the spine, while pathology in the hip can produce pain in the knee. A simple test which can help distinguish pathology in the hip from pathology elsewhere is the ‘pastry rolling test’. With the patient lying supine on the couch start with the unaffected side. Place the palm of one of your hands on the patient’s shin, and the other on their thigh. Keep your hands flat with the fingers straight, and roll the leg as one to and fro under your hands as if you were rolling pastry. If there is no problem in the hip, the patient will relax completely after a couple of rolls, and their four will flop to and fro at the end of the leg (Fig. 20.21). Repeat the test on the affected side. If there is pain and/or stiffness in the hip joint the patient will not relax, the foot will not flop to and fro, and there will be a distinct resistance to movement at the end of internal and external rotation. Pathology in the knee dues not do this because the knee joint is being rolled as one. Similarly, the sciatic nerve is not irritated by internal and external rotation of the hip, so pathology in the spine has no effect on this test.