EPIDEMIOLOGY OF SLIPPED CAPITAL FEMORAL EPIPHYSIS IN SLOVENIA BETWEEN 1970 AND 2006

Abstract

Background: Slipped capital femoral epiphysis (SCFE) is an important orthopaedic problem which emerges in early adolescence. Not clearly identified factors in the growth zone of proximal femur produce slip in which the femoral head remains in the acetabulum and femoral shaft rotates outwards and backwards. This occurs usually in one but occasionally in both hips. As we assumed that in Department of orthopaedic surgery in Ljubljana half of Slovenian adolescent population with SCFE was treated, we could calculate epidemiological data for SCFE for whole Slovenian population.

Patients and Methods: In retrospectively study we analysed patients treated operatively at Department of orthopaedic surgery in Ljubljana between 1.1.1970 and 31.12.2006. The data about sex, age and side of the slips were collected. We calculated average age at occurance, ratio boys to girls, and predominance of left or right side. For determination of SCFE incidence in Slovenia, we used the attack rate method which is the sum of annual incidences of SCFE in age interval when the slips occur calculated for each one-year group.

Results: There were 224 patients, 126 boys and 98 girls presenting with SCFE between 1970 and 2006 treated in Department of orthopaedic surgery in Ljubljana. The average age of boys was 12.9 and the age of girls 11.6 years (range: 8–16 years). On the average the age was 11.3 years. Slipped capital femoral epiphysis appeared more frequently on the left side (58%) than on the right side (31%). In 11% of cases the slips were bilateral. Incidence per 1000 adolescents extrapolated to Slovenian population (attack rate method) was 0,796 ‰ for boys, 0,667 ‰ for girls and 0,734 ‰ for entire endangered population. Yearly incidence of SCFE was thus 0,089 ‰ for boys and 0,073 ‰ for girls.

Discussion: Epidemiological data for SCFE in Slovenia are comparable to those found in Sweden and is difficult to compare with other countries, where different statistical methods were used. Risk of getting SCFE in critical period for boys is 1:1265 and for girls: 1:1499. Risk for whole critical population is 1:1362. It is interesting that our study showed marked increase in the number of boys with SCFE in recent years. Boys to girls ratio has changed from 1:1 in years 1970 to 1994 (Zupanc in sod. 2002) to 1,29:1 in our study.