Highlights
- •Piriformis entry reconstruction nails with any interlocking screw configuration do not protect the femoral neck.
- •Two proximal interlocking (reconstruction) screws have higher load to failure than a single screw.
- •Two reconstruction screws did not increase the load to failure compared to having no reconstruction screws.
Abstract
Objectives
Prophylactic femoral neck fixation may be performed in the setting of geriatric diaphyseal
femur fracture, pathologic or impending atypical femur fractures. Fixation constructs
often utilize cephalomedullary implants with one or two proximal interlocking screws
into the femoral head/neck. Variations in proximal femoral anatomy and implant design
can interfere with the placement of two screws in the femoral head and neck. Our objective
was to assess the strength of piriformis entry reconstruction implants with one versus
two proximal interlock screws for prophylactic femoral neck fixation.
Methods
Thirty fourth generation synthetic femur models were separated into 5 groups. The
control group was an intact femur, and the second group was an intact femur with an
entry hole in the piriformis fossa. The remaining groups had an intramedullary nail
placed with either 0, 1, or 2 screws placed into the femoral head and neck. Each femur
was mechanically loaded along the mechanical axis through the femoral head. Load to
failure and failure displacement were recorded.
Results
Mean load to failure was 5583 ± 543 N in the intact femur. Constructs with 2 screws
had a significantly higher mean load to failure (3223 ± 474 N) compared to one screw
constructs (2368 ± 280 N). All of the experimental groups remained significantly lower
than the intact femur model (p < 0.05).
Conclusion
Our results demonstrate that piriformis entry reconstruction implants have a significantly
lower load to failure compared to an intact femur irrespective of screw construct.
Further studies are needed to investigate this potential iatrogenic weakening.
Keywords
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Article info
Publication history
Published online: October 17, 2018
Identification
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© 2018 Elsevier Ltd. All rights reserved.
