Complications and associated risk factors at screw removal in slipped capital femoral epiphysis treated by cannulated stainless steel screws.

Purpose: The aim of our study is to report our complication rate and analyze the associated risk factors when removing cannulated stainless steel screws for SCFE fixation.

Methods: This was a multicenter retrospective study of patients who underwent removal of cannulated stainless steel screws after a mean time of 2.03 years of implantation. Thirty-two patients were included (38 hips) with a mean of 13.7 years of age during screw removal surgery. The mean post-removal follow up time was 1.6 years. In all cases the removal of screws was done systematically. Demographic data, possible risk factors related to removal failure, as well as post-removal complications such as post-removal fractures, infections and scar issues were recorded.

Results: A removal failure rate of 15.79 % (6/38) was found. The removal surgical time was longer than the initial fixation time but without statistical significance (70.78 vs 61.84 m, p = 0.196). However, the duration of screw implantation (r (2): 7.09; IC: 1.12-13.06) and screw head bony coverage (r (2): 21.32; IC: 5.58-37.06) were both related to this prolonged time. Multivariant analysis revealed that a fully threaded cannulated screw had the lowest removal failure risk (OR: 0.3; IC: 0.14-0.61). There were no postremoval complications recorded.

Conclusions: We recommend to use full threaded cannulated stainless steel screws and to perform the procedure as soon as the physis are closed to decrease the surgical time. It is a safe procedure based on a low rate of complications such as post-removal fractures, infection and scar issues.