Slipped capital femoral epiphysis is an important orthopaedic problem of early adolescence. Many hypotheses about its etiology have been proposed; still the underlying mechanisms are not clearly understood. The aim of our paper is to examine radiographic characteristics of hips at risk for slipped capital epiphysis.

Two groups of hips were compared: a group of 100 asymptomatic hips contralateral to the slipped ones and a group of 70 age- and gender-matched healthy hips. The hips contralateral to the slipped ones were assumed to have identical morphology to the preslip-page morphology of the slipped hips. In each hip the following radiographic parameters were measured: the inter-hip distance, the femoral neck length/width, the pelvic height, the pelvic width, the femoral head radius, the coordinates of the abductor muscles trochanteric attachment, the inclination of the femoral epiphyseal growth plate, the femoral neck-shaft angle and the Wiberg center-edge angle.

Subjects with hips at risk for slipping had significantly higher body weight (590 vs. 500 N; p < 0.001), larger diameter of the femoral neck (38.6 vs 37.3 mm; p = 0.027), higher (138.9 vs. 134.6 mm; p = 0.022) and wider pelvis (53.8 vs. 48.7 mm; p < 0.001) and more laterally placed abductor muscles trochanteric attachment. There were no significant differences in the inter-hip distance, the femoral head radius, the femoral neck length and the femoral neck-shaft angle angle. Hips contralateral to the slipped ones had a more vertically inclined physeal angle (55.4 vs. 63.2 degrees; p < 0.001) in comparison to the healthy hips. The Wiberg centre-edge angle of the hips contralateral to the slipped ones was on average 7% larger from the healthy group (34.7 vs. 32.2 degrees; p = 0.003).

Children with hips at risk for slipping had larger pelvices and femora with more vertically inclined femoral epiphyseal growth plate. In addition, one cannot overlook the significant difference in the body weight between the age- and gender-matched groups of our study, confirming previous findings on the role of body weight in SCFE. It is therefore possible that anatomical changes may be a downstream effect of bone remodelling caused by altered loading during growth and development. This may suggest that the predisposition of the hip to slipping occurs earlier in the patient’s lifetime and that targeted radiographic examinations in obese individuals could reveal changes in pelvic geometry even before adolescence. Considering the high rates of bilateral involvement, our results could be used to predict the need for preventive fixation of asymptomatic hips after the capital femoral epiphysis has slipped in the contralateral hip.

Background and Aims: Concentric pressure of the femoral head on acetabulum is the necessary prerequisite for normal hip development. In the case of diminished hip joint area an elevation of hip joint pressure ensues. If this pressure elevation lasts for a long period of time early degenerative changes are proposed to occur. The aim of our study is to substantiate the connection between hip joint pressure and occurrence of hip osteoarthritis in dysplastic hips. Methods: From 1955 to 1965 112 patients were treated non-operatively for hip dysplasia in developmental dysplasia of the hip in Dept. of Orthopaedic Surgery, Ljubljana. Using mathematical model of the hip, peak joint stress was measured in 27 patients, which met the enrolment criteria consisting of: a.) initial rentgenograph taken at least 20 years ago, b.) closed triradiate cartilage and no rentgenographic signs of osteoarthritis at the time of initial radiograph, c.) no neurological deþcit of lower limbs and no operative procedure during follow up period. All hips were re-examined clinically in year 2000. Results: Mean age at the latest follow up was 47 years (35 years to 61 years). Mean time interval between the rentgenograph from which the hip joint stress was measured and clinical examination was 27 years (20 years to 33 years). Signiþcant correlation was found between peak hip joint stress and Harris hip score (p 0.0013). Discussion and conclusions: Our results indicate that occurrence osteoarthritis of the hip could be related to the degree of hip dysplasia at the end of skeletal growth. The correlation between peak hip joint stress and Harris hip score was one order of magnitude larger than the corresponding correlation between CE angle and Harris hip score, which indicates that hip joint stress represents a valuable parameter describing the status of the hip joint.