Reliable X-ray diagnosis of slipped capital femoral epiphysis by combining the conventional and a new simplified geometrical method

Background: The diagnosis of subtle slipped capital femoral epiphysis (SCFE), for example in the contralateral asymptomatic hip, may require use of an exactly defined and reproducible lateral view where the slipping angle can be measured. Objective: To test a simplified geometrical method and compare it to the conventional method (AP and frogleg views). Materials and methods: The two methods were compared in 95 normal children 9-14 years old and 100 children 9-20 years old with SCFE. Results: The slipping angle (SA) measurements had very high reproducibility, and the new method was diagnostically superior to the conventional method (P < 0.05). Conclusion: An exactly defined and reproducible lateral view is recommended for the X-ray diagnosis of SCFE. Nontraumatic SCFE appears to be bilateral in all cases.