Extracapsular base-of-neck osteotomy: measurement of head-shaft angles on radiograph. A, Normal anteroposterior angle compared with slipped capital femoral epiphysis (SCFE). B, Moderate SCFE shows decrease in anteroposterior head-shaft angle. C, Normal acute angle. D, Severe slip shows increase in frog-leg lateral head-shaft angle. (From Abraham E, Garst J, Barmada R: Treatment of moderate to severe slipped capital femoral epiphysis with extracapsular base-of-neck osteotomy, J Pediatr Orthop 13:294, 1993.) SEE TECHNIQUE 36.27.