Congenital dislocation of the hip (CDH)

Congenital dislocation of the hip causes no symptoms at birth, so it has to be diagnosed by screening all newborn babies. The danger is that it may cause premature osteoarthritis in later life. If however you can recognize a baby's dislocated hip at birth, reduce it, and hold it in place with a simple splint, you can usually cure him and prevent later complications. In many communities (Africa) it is rare, but in those where it is not, it is worth screening for.

If he is not diagnosed at birth, he may present with a limp (often very mild) when he starts to walk. His leg may then be shortened and his hip unstable. If however his dislocation is bilateral, you will not be able to diagnose shortening, and he may appear to walk normally, although careful observation should show a slight waddle. Baby girls are more likely to dislocate their hips than baby boys.

Fig. 27-15 CONGENITAL DISLOCATION OF THE HIP. A, B, and C, Ortolani's test. D, if a patient is older, his leg may be slightly shorter, and his hip externally rotated. The skin folds of his thigh may be asymmetrical (E), but this sign is not very reliable. If both hips are involved the perineum is usually widened owing to their displacement (F). If a patient has been walking his lumbar lordosis may be increased (G). After Ronald McRae, permission requested.

CONGENITAL DISLOCATION OF THE HIP DIAGNOSIS. In communities where CDH is sufficiently common to make routine screening worthwhile, examine all children soon after birth. CDH can be confirmed radiologically, but the methods of doing so are not described here.

In a baby do Ortolani's test. Fig. 27-15 shows the test being done in a girl. She must be relaxed, preferably after she has been fed. Flex her knees and hold so them so that your thumbs are along the medial sides of her thighs, and your fingers are over her trochanters (A). Flex her hips to 90[de]. Starting from a position in which your thumbs are touching, abduct her hips smoothly and gently (B).

If a hip is dislocated or subluxed, you will feel the head of her femur slipping into her acetabulum as you approach full abduction (C). You may hear a ''clunk', but this is not essential for the test to be positive. Restriction of abduction may indicate an irreducible dislocation. If the test is positive she must be treated.

If a patient is older, one leg may be slightly shorter, and the hip externally rotated (D). The skin folds of the thigh may be asymetrical (E), but this sign is not very reliable. If both hips are involved the perineum is usually widened due to their displacement (F). If walking has started, the lumbar lordosis may be increased (G).

THE TREATMENT OF CDH If she is a neonate, treat her in double nappies which will hold her hips in flexion and abduction. Examine her again at one week. If her displaced hip has become stable, apply double nappies for a further 3 weeks, and examine her again. If it is still stable, one nappy only is necessary.

If instability persists, he needs a more substantial splint. Ideally use the von Rosen splint (B, 27-15a). Alternatively, the simplest splint is a sheet of stiff polythene, padded round its edges, which passes between her abducted legs over her nappy. The edges of the sheet are held together at either side by two pieces of ''Velcro' strapping. If you cannot obtain such a splint, you may be able to improvise one.

Apply the splint for 3 months. Then examine her hip again and X-ray it. If there is any doubt that it is not in place, refer her.

DIFFICULTIES [s7]WITH CDH If you DIAGNOSE CDH LATE (over the age of 3 months), she needs skilled surgery, so consider referring her. If she is over 8 years this will be difficult. If a good range of movement is particularly important, as in societies where people squat, an unstable mobile hip may be preferable to a stiff one, whatever the risk of later arthritis.

If REDUCTION IS DIFFICULT or impossible, consider other causes for the dislocation: (1) Partly treated septic arthritis or tuberculous arthritis. (2) A congenital abnormality, and particularly ARTHROGRYPOSIS (rare), as shown by: (a) the absence of skin creases, (b) generalized rigidity of the muscles often of both legs, and sometimes of all four limbs. If you recognize this condition, don't attempt reduction, which may be impossible[md]refer her. X-rays should distinguish between (1) and (2).

Fig. 27-15a A SPLINT FOR CONGENITAL DISLOCATION OF THE HIP. A, the simplest splint is a sheet of stiff polythene, padded round its edges, which passes between the child's legs over her nappy. B, ideally use the von Rosen splint made of washable malleable padded metal.