title: Does screw configuration affect subtrochanteric fracture after femoral neck fixation?
abstract: A subtrochanteric femur fracture after cannulated screw fixation of a femoral neck fracture is a devastating complication. We hypothesized that an apex-distal screw orientation would tolerate higher loads to subtrochanteric fracture. Human cadaveric femora were instrumented with three cannulated screws in either an apex-distal or an apex-proximal configuration. Specimens were loaded along the mechanical axis to failure creating a subtrochanteric femur fracture. Ultimate load to failure and the effect of bone density on load to failure were compared between groups. There was a greater load to failure in the apex-distal group compared with the apex-proximal group. The mean force to fracture in the apex-distal group (11,330 N; standard deviation = 3151 N) was greater than the mean force to fracture in the apex-proximal group (7795 N; standard deviation = 3194 N). Previous investigations have shown improved femoral neck fixation with an apex-distal configuration, but none has examined the relationship between screw orientation and subtrochanteric fractures. Our observations support the use of an apex-distal configuration for cannulated screw fixation of femoral neck fractures.
authors.affiliation: Loyola University Medical Center, Maywood, IL 60153, USA.
authors.forename: Jerome W
authors.initials: JW
authors.lastname: Oakey
authors.forename: Michael D
authors.initials: MD
authors.lastname: Stover
authors.forename: Hobie D
authors.initials: HD
authors.lastname: Summers
authors.forename: Mark
authors.initials: M
authors.lastname: Sartori
authors.forename: Robert M
authors.initials: RM
authors.lastname: Havey
authors.forename: Avinash G
authors.initials: AG
authors.lastname: Patwardhan
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws / Q000009:adverse effects*; D002102:Cadaver; D005264:Femoral Fractures / Q000209:etiology* / Q000503:physiopathology; D005265:Femoral Neck Fractures / Q000601:surgery; D005269:Femur / Q000503:physiopathology / Q000601:surgery; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000295:instrumentation*; D006801:Humans; D066298:In Vitro Techniques; D011183:Postoperative Complications