1. Experimental work with piglets supports the theory that diminished blood supply to the femoral head not only causes necrosis of the epiphysis but also a decrease in cartilage cell production in the germinal layer of the epiphysial plate, thus causing decreased longitudinal bone growth. Appositional growth continues in the metaphysis because its blood supply remains intact or, at least, is less impaired. The resulting disturbance of the normal remodelling must lead to a short wide neck such as occurs in Legg-Perthes' disease. 2. Measurements were made of the length and width of the femoral neck on radiographs of forty patients with Legg-Perthes' disease. The results showed that the degree of shortening and widening is related to the extent of structural change in the head. 3. Repeated measurements in the early stages of the active disease may permit an early prognosis which may be of great assistance in selecting the treatment suitable to each patient. The financial assistance of the Ontario Society for Crippled Children is gratefully acknowledged

1. The duration of Legg-Perthes' disease seems somewhat shortened by abduction weightbearing plaster treatnlent. The average age of onset of our sixty patients at the start of this treatment was seven years nine months. The patients were treated in abduction plasters for an average of nineteen months. 2. The contour of the femoral head in relation to the acetabulum is better preserved than after our previous methods of treatment. We have evaluated our cases by the method of Mose, by the epiphysial index of Eyre-Brook and the epiphysial quotient of Sjovall, and by the centre/edge angle of Wiberg. 3. There was no undue influence on the growing epiphysis and no evidence of ligamentous strain. 4. With this type of protected weight-bearing, the patients were kept active when both hips were affected. 5. No patient with unilateral disease showed Legg-Perthes' changes on the opposite side while under treatment or at follow-up. 6. The children were able to be at home and to attend school

Perthes’ disease is an osteonecrosis of the juvenile hip, the aetiology of which is unknown. A number of comorbid associations have been suggested that may offer insights into aetiology, yet the strength and validity of these are unclear. This study explored such associations through a case control study using the United Kingdom General Practice Research database. Associations investigated were those previously suggested within the literature. A total of 619 cases of Perthes’ disease were included, as were 2544 controls. The risk of Perthes’ disease was significantly increased with the presence of congenital anomalies of the genitourinary and inguinal region, such as hypospadias (odds ratio (OR) 4.04 (95% confidence interval (CI) 1.41 to 11.58)), undescended testis (OR 1.83 (95% CI 1.12 to 3.00)) and inguinal herniae (OR 1.79 (95% CI 1.02 to 3.16)). Attention deficit hyperactivity disorder was not associated with Perthes’ disease (OR 1.01 (95% CI 0.48 to 2.12)), although a generalised behavioural disorder was (OR 1.55 (95% CI 1.10 to 2.17)). Asthma significantly increased the risk of Perthes’ disease (OR 1.44 (95% CI 1.17 to 1.76)), which remained after adjusting for oral/parenteral steroid use.

Perthes’ disease has a significant association with congenital genitourinary and inguinal anomalies, suggesting that intra-uterine factors may be critical to causation. Other comorbid associations may offer insight to support or refute theories of pathogenesis.

1. Transient synovitis is an acute, and at times exudative, condition of the synovial membrane. 2. There is no particular association with injury or with upper respiratory infection. 3. The course is short and benign with complete resolution. The occasional hip with chronic or recurrent symptoms can be distinguished from Legg-Perthes' disease by the shorter history, normal radiographs and the complete resolution. 4. There is no evidence that transient synovitis leads to avascular changes in the femoral head

1. After exclusion of the well known causes of torsion such as congenital dislocation of the hip, Legg-Perthes' disease, cerebral palsy and congenital talipes equinovarus, examination of 1,320 nearly normal children disclosed an incidence of 13·6 per cent toeing-in or toeing-out. 2. There was a female preponderance of seven to three on presentation decreasing to four to three in uncorrected cases. 3. There was persisting upper femoral torsion of greater than 10 degrees in two-thirds of all cases of toeing-in whether corrected or uncorrected. 4. When correction of toeing-in occurred it took place between four and seven years of age, but mainly at five years. 5. There was a normal angle of anteversion in one-third of children whose toeing-in was not corrected. This suggests the possibility of acetabular maldirection. 6. Uncorrected torsional stresses may play a part in the later development of osteoarthritis