Slipped capital femoral epiphysis (SCFE) is a common hip disorder in adolescents. Treatment consists of in-situ percutaneous fixation using either a fully threaded or partially threaded cannulated screw. Instances of modern hardware failure from a broken screw are exceedingly rare in the literature. We present two reports of broken partially threaded cannulated screws following fixation of SCFE.
Case Report: 1:
A 14 y/o male underwent fixation of an acute right SCFE discovered after three weeks of groin pain. His post-operative course was uneventful. Six months following his index procedure, he began participating in sports. His groin pain returned, and radiographs revealed a broken screw. He underwent revision fixation and broken screw removal. (Image Series 1.1-1.4)
Case Report 2:
A 13 y/o male underwent fixation of a chronic left SCFE following years of groin pain. Several months following his index procedure, he required fixation of his right SCFE. At routine follow-up one year later the patient was asymptomatic, but was noted to have a broken screw in the right hip with no evidence of physeal fusion on either side. Endocrinopathy workup was negative. He returned to the operating room for repeat fixation of his right and left SCFE to stimulate physeal fusion. (Image Series 2.1-2.4)
Fixation of SCFE using cannulated screws is a common procedure performed in pediatric orthopaedics. The purpose of fixation is to relieve pain by preventing further slip of the epiphysis and to stimulate physeal fusion. The most common reasons for failure of SCFE fixation include physeal abnormalities from endocrinopathy, inadequate thread purchase in the epiphysis, and hardware failure. Although complications from screw placement are abundant in the historical literature, instances of modern hardware failure are rare. Failed hardware due to broken screws has been associated with increased operating times and blood loss, delayed recovery, and subtrochanteric femur fractures.
Orthopaedic surgeons must weigh the risks and benefits to partially versus fully threaded screws when treating patients with SCFE. Biomechanically, with all threads across the physis, partially threaded screws have the ability to achieve compression across a SCFE, theoretically resulting in faster times to physeal fusion. However, the smooth shank can be a stress riser, resulting in screw breakage. Alternatively, fully threaded screws are structurally stronger due to more threads in bone, but they do not compress across the physis; acting only as a stabilizer. Recent research has shown that fully threaded screws are superior to partially threaded screws in preventing future slip of the epiphysis. We now consider fully threaded screw fixation in treatment of most SCFE at our institution due to the increased mechanical strength and decreased risk of reoperation from a broken screw.