Screw Diameter and Use of a Washer Affect Symptomatic Implant Removal Rates in Pediatric Medial Epicondyle Fractures.

Abstract

Medial epicondyle fractures are a common pediatric injury. When operative, cannulated partially threaded screws, with or without a washer, are commonly utilized. These implants may need to be removed after full healing if symptomatic. There is mixed evidence regarding the influence of a washer on rates of implant removal, and the influence of screw size has not been studied. We aim to determine the rate of symptomatic deep implant removal for each fixation type and identify factors associated with the need for removal. This was an IRB-reviewed, retrospective, case-cohort study. Patients treated at our institution between January 1, 2004 and December 31, 2019, age 18 years old or younger, with a medial epicondyle fracture managed operatively with 4.0 or 4.5mm cannulated screws with or without washers were included. Patients with multiple operative ipsilateral elbow fractures and those who underwent implant removal for reasons other than pain or irritation were excluded. Removal rates were compared between screw sizes (4.0 vs 4.5mm), as well as with and without a washer using a Cox proportional hazards model. In total, 151 patients met the inclusion criteria, 54 with symptomatic hardware removed and 97 without symptomatic hardware removed. A significantly higher number of patients treated with 4.5mm screws compared with 4.0mm screws underwent removal of symptomatic deep implants (50% vs 30%, P = 0.033). In a multivariable Cox regression model adjusting for age and ulnar nerve status, when no washer was used, the hazard ratio (HR) for symptomatic hardware removal for 4.5mm screws was 2.92 times the HR for 4.0mm screws (95% CI: 1.35-6.29). When a 4.0mm screw was used, the HR for symptomatic hardware removal for a washer was 3.24 times the HR without a washer (95% CI: 1.53-6.84). Implant removal rates are influenced by screw size and the use of a washer. These results may help guide implant choice and counsel families regarding the rate of symptomatic implant removal. Level III-therapeutic level, case-control study.