Initial assessment of the hip joint is with the patient lying flat and straight on a couch, in the supine position, with a single head pillow and wearing briefs. The neutral position of the hip is in extension with the patella pointing forward. Although the muscles and bones around the joint limit the value of inspection and palpation, an abnormal posture of the limb may indicate pain, deformity and altered mobility. Observe the symmetry of skin creases, and the contour of the thighs and buttocks in each part of the examination. The anterior surface marking of the joint is just inferior and posterior to the midinguinal point and pressure at this site may reveal joint tenderness.
The greater trochanter is palpable and is on, or just below, a line joining the anterior superior iliac spine with the ischial tuberosity (Nelaton’s line on a lateral hip radiograph).
The relative position of the two hip joints can be roughly compared, by placing your thumbs on the anterior superior iliac spines and your middle fingers on the greater trochanters (figure 74 – other pelvic landmarks are considered with the spine – page 91). Figure 75a shows a normal anteroposterior radiograph of the pelvis and hip joints; note the shortening of the femoral neck associated with fracture of the neck of the femur in figure 75b.
With a subject lying on a couch, the intersection point of the line passing vertically backwards through the anterior superior line and the horizontal line through the greater trochanter, is approximately 4cm from the trochanter in the adult. Reduction of this distance may indicate abnormalities of the neck of the femur. The triangle of this intersection point and the two bony markings make up Bryant’s triangle (figure 76).
Figure 76 Bryant’s triangle
Bryant’s triangle: with patient supine, perpendicular line AB from anterior superior iliac spine joins horizontal from greater trochanter – compare BC on two sides for shortening of femoral neck
Abnormalities of the hip joint may alter leg length and there may be true and/or apparent shortening; the latter is due to abnormal tilting of the pelvis. First ask the patient to lie straight on the bed. True shortening is measured between the anterior superior iliac spine and the medial malleolus on each side (figure 77a,b), or an equivalent position on each leg, such as the medial femoral condyle or the patella. Apparent shortening is between the umbilicus or sternal angle and each medial malleolus (figure 77c,d).
When both knees are bent and the feet placed together on the couch, differences of leg length can also be demonstrated by differences in the position of the two knee joints, and whether the difference is above or below the knee (figure 78).
Examine for abnormal mobility of the hip joint by gripping the flexed thigh with both hands, and feeling the presence of any telescopic movement, when pulling and pushing along the length of the limb.