Bone growth after fixing slipped femoral epiphyses: brief report.

Early closure of the growth plate after fixing a slipped upper femoral epiphysis is often regarded as favourable since, if growth of the femoral neck continues, the metal may lose its grip on the epiphysis with the possibility of further slipping. However, in the young child early fusion may result in leg length discrepancy and limited motion. The hook-pin (Hansson 1982) permits continued growth of the femoral neck without the risk of further slipping, as illustrated in the following cases. Patients and methods. Four boys with unilateral and two boys with bilateral slipping of the upper femoral epiphysis were treated. Those which had slipped were pinned without reduction ; those which had not slipped were pinned prophylactically. In all cases the hook-pin was used (Fig. 1). Two of the boys were aged 1 2 years at operation, three were aged 1 3, and one 14 years. The boy aged 14 had a bilateral chronic severe slip; the other five all had slipping of less than a third of the diameter of the femoral head. During the operation one or two tantalum balls were inserted into the epiphysis, into the base of the femoral neck, and into the top of the greater trochanter in both hips. The children were followed-up with repeated roentgenstereophotogrammetric examinations until the growth plate of the femoral neck had closed ; the error of this method is less than 50 mm (Selvik, Alberius and Arondson 1983). Results. Ten hips showed a growth in length of the femoral neck of between 8.9 and 15.2 mm (Table I and Fig. 2). These ten hips also showed a growth of the greater trochanter ranging from 8. 1 to 1 3.5 mm. There was no significant difference in growth between the slipped and the unslipped hips. In the boy aged 14 years at operation no significant growth of the femoral neck or the greater trochanter occurred. None ofthe hips showed segmental collapse or chondrolysis. At re-examination three to six years after growth plate closure, all the boys had painfree hips, with normal function and a normal range of movement apart from slightly reduced medial rotation.