Biomechanical analysis of impending femoral neck fractures: the role of percutaneous cement augmentation for osteolytic lesions.
BACKGROUND
Management of impending pathologic femoral neck fractures includes internal fixation, arthroplasty and megaprostheses. The study aim was to determine the augmentative effect of cement injection for minimally invasive treatment of femoral neck lesions.


METHODS
Twenty-seven cadaveric femora received a simulated osteolytic lesion previously shown to decrease the femur's failure load by 50%. Specimens were allocated to three groups of nine and loaded to failure in simulated single-leg stance: (1) percutaneous cementation + internal fixation (PCIF); (2) percutaneous cementation (PC); and (3) internal fixation (IF). Lesion-only and augmented finite element models were virtually loaded and stresses were queried adjacent to the lesion.


RESULTS
PCIF resulted in the largest failure load though the increase was not significantly greater than the PC or IF groups. Inspection of the PC and PCIF specimens indicated that the generation of a cement column that spanned the superior and inferior cortices of the femoral neck increased failure loads significantly. Finite element analysis indicated that IF and PCIF constructs decreased the stress adjacent to the lesion to intact femur levels. Cementation without superior-to-inferior femoral neck cortical contact did not restore proximal femoral stress toward the intact condition.


CONCLUSIONS
Internal fixation alone and internal fixation with or without cementation produce similar levels of mechanical augmentation in femora containing a high-risk lesion of impending fracture. A cement injection technique that produces a cement column contacting the superior and inferior femoral neck cortices confers the highest degree of biomechanical stability, should percutaneous cementation alone be performed.
Florida Orthopaedic Institute, Tampa, FL, USA.
Brian T
BT
Palumbo
Department of Orthopaedics and Sports Medicine, University of South Florida, Tampa, FL, USA.
Charles
C
Nalley
Department of Orthopaedics and Sports Medicine, University of South Florida, Tampa, FL, USA.
Roger B
RB
Gaskins
Foundation for Orthopaedic Research and Education (FORE), Tampa, FL, USA.
Sergio
S
Gutierrez
Department of Orthopaedics and Sports Medicine, University of South Florida, Tampa, FL, USA.
Gerald E
GE
Alexander
Foundation for Orthopaedic Research and Education (FORE), Tampa, FL, USA.
Leon
L
Anijar
Foundation for Orthopaedic Research and Education (FORE), Tampa, FL, USA.
Aniruddh
A
Nayak
H. Lee Moffitt Cancer Institute, Tampa, FL, USA.
David
D
Cheong
Department of Orthopaedics and Sports Medicine, University of South Florida, Tampa, FL, USA; Foundation for Orthopaedic Research and Education (FORE), Tampa, FL, USA. Electronic address: bsantoni@foreonline.org.
Brandon G
BG
Santoni
D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000627:therapeutic use*; D002102:Cadaver; D002484:Cementation / Q000379:methods*; D005265:Femoral Neck Fractures / Q000517:prevention & control*; D005272:Femur Neck / Q000601:surgery; D020342:Finite Element Analysis; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D010014:Osteolysis / Q000150:complications / Q000628:therapy
D001843:Bone Cements
Biomechanics; Femoroplasty; High risk lesion; Impending fracture; Minimally invasive augmentation