The etiology and treatment of congenital dislocation of the knee.

Congenital dislocation of the knee was described by Chatelaine in 1822 (quoted by Shattock 1891) and then by Bord in 1834 (quoted by Forgon and Szentp#{233}tery 1961). It was at first thought to be more common in girls, but in a review of a larger series of cases the sex distribution was found to be equal (Provenzano 1947). Kopits (1925) reviewed 2,393 patients with congenital anomalies and found eleven cases of congenital dislocation of the knee as compared with 923 cases of congenital dislocation of the hip, or one dislocated knee for every eighty-four dislocated hips. Sixty per cent of the patients with congenital dislocation of the knee have other congenital anomalies, congenital dislocation of the hip and foot deformities being the most common. Cleft palate, harelip, chest cage deformities, hypoplasia of the fibula and dislocation of the elbow are some of the other deformities seen with congenital dislocation of the knee (Forgon and Szentp#{233}tery 1961). In some of the families studied genetic transference of the condition has been evident. In Provenzano’s (1947) review of 200 cases, seven patients had a family history of congenital dislocation of the knee. McFarlane (1947) described a family in which a mother and her three children by three different fathers all had congenital dislocation of the knee. Etiology-Both intrinsic and extrinsic causes have been suggested. The intrinsic causes are genetic abnormalities ; the extrinsic causes are mechanical factors. Duraiswami (1955) pointed out that it is often difficult to distinguish between genetically inherited anomalies and those produced by adverse factors occurring during the development of the embryo. Some of the extrinsic causes suggested have been abnormal foetal position, primary contracture of the quadriceps muscles, and traumatic dislocation during parturition. Shattock (1891) and Drehmann (1900) postulated an abnormal foetal position during gestation as the cause of congenital dislocation of the knee. In cases that they reported the patients had breech deliveries with the knees in a hyperextended position and the feet locked under the chin. This position produced a hyperextension force at the knee, causing it to dislocate. This theory failed to explain the etiology in those cases-the majority-in which there is not a breech delivery, although the percentage of breech deliveries with congenital dislocation of the knee is higher than the expected 3 to 4 per cent of breech deliveries in the general population. Middleton (1935) believed that the deformity was the result of a primary contracture of the quadriceps muscle. He came to this conclusion after finding these muscles to be partly replaced by fibro-fatty tissue. This has not been accepted because the author failed to prove that the muscle changes were really primary and not a secondary effect of the dislocation. Trauma to the knee during birth was implicated as a cause of the dislocated knee by Mauclaire (quoted by Forgon and Szentp#{233}tery 1961). This is no longer an accepted theory because it has been shown in dead infants that when an attempt is made to produce anterior dislocation of the knee, the femoral epiphysis will displace before the knee will dislocate.