Thirty-seven patients with a total of 39 hips affected by Legg-Calvé-Perthes' disease were treated in conservative fashion. The follow-up period ranged from 5 to 18 years and 7 months, and averaged 9 years and 2 months. The average age at first visit was 6 years and 5 months.
We determined the number of head-at-risk signs and the Catterall classification using a radiograph obtained during the initial period of treatment. The CE angle, articulo-trochanteric distance, acetabular head index and epiphyseal index were measured on the final radiograph, and assessment was made using Stulberg's criteria. Five hips were in Catterall group 2, 25 in group 3, and 9 in group 4. Twenty-one of the 39 hips (53.8%) were in Stulberg class 1 and 2 at final follow-up. Of 5 hips initially in Catterall group 2, good results were obtained for 4 (80.0%), however, only one from 9 hips in group 4 (11.1%) showed good in results and other 8 hips in poor. Of 25 hips in group 3, good results were obtained for 16 (64.0%) and poor results for nine. The number of head-at-risk signs was also determined. If two or more head-at-risk signs were found, the result of treatment tended to be poor. Of 18 hips in patients under 6 years of age at first visit, good results were obtained for 11 (61.1%), and other 3 hips had final assignments to Stulberg group 4 or 5. Significant correlations were found between Stulberg radiographic classes and each of Catterall group assignment, the number of head-at risk signs and the age at fist visit.
Nineteen hips treated with the Snyder sling was compared with another group of 15 hips treated with the Pogo stick. Good results were obtained for 11 hips (57.9%) of the former group and 8 (53.3%) of the latter. The difference between the two groups was not significant. But if only cases in group 3 are considered, treatment with the Pogo stick yielded better results.
These findings indicated that it is necessary for this disease to follow carefully even in patients under 6 years of age at first visit.
