Background: Moderate to severe slipped capital femoral epiphysis leads to premature 
osteoarthritis resulting from femoroacetabular impingement. Modified dunn procedure restore the 
normal anatomy, complete correction of the slip angle, and minimize the probability of cam-type 
FAI with preservation of physeal blood supply. Patients, Methods: A prospective study was 
conducted on 15 patients with moderate and severs SCFE were treated with modified dunn 
procedure during the period from March 2017 to February 2020 , 12 males (80%) and 3 females 
(20%) with mean age was 15.2 years at the date of surgery The Right hip was affected in 9 patients 
(60%) and the left hip in 6 patients (40%). 10 cases were stable, while 5 cases were unstable. The 
mean follow up period was 15.1 month. Results: Postoperatively, the harris hip score (HHS) 
ranged from 60 to 100 with mean value 93.7 (SD was 13), WOMAC score ranged from 0 to 20 
with mean value 3.7 (SD was 5.5) and the Heyman and Herndon score was excellent-good in 13 
cases (86.7%),and poor in two cases (13.3%). Radiologically, all parameters showed significant 
improvement with the mean slip angle corrected from 53.90
(SD 11.7) preoperatively to 5.10
(SD 
5.7) postoperatively, the mean alpha angle corrected from 1000
(SD 14.1) preoperatively to 51.9 
(SD 5.3) postoperatively. AVN and implant removal occurred in only two cases (13.3%).
Conclusion: Capital realignment through the modified dunn procedure is an effective and safe 
treatment option for moderate and severe SCFE in patients with open physes as it allows 
anatomical restoration of hip anatomy thus preventing FAI with its sequalae and and provide good 
short-term outcome with low complication rate.