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Hip resurfacing increases bone strains associated with short‐term femoral neck fracture
Author(s) -
Long Jason P.,
Santner Thomas J.,
Bartel Donald L.
Publication year - 2009
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.20884
Subject(s) - notching , medicine , femoral neck , implant , fracture (geology) , strain (injury) , hip resurfacing , ultimate tensile strength , surgery , dentistry , orthodontics , materials science , anatomy , osteoporosis , composite material , metallurgy
Short‐term femoral neck fracture is a primary complication associated with contemporary hip resurfacing. Some fractures are associated with neck notching, while others occur in the absence of notching. These unexplained fractures may be due to large magnitude strains near the implant rim, which could cause bone damage accumulation and eventual neck fracture. We used statistically augmented finite element analysis to identify design and environmental variables that increase bone strains near the implant rim after resurfacing, and lead to strain magnitudes sufficient for rapid damage accumulation. After resurfacing, the compressive strains in the inferior, peripheral neck increased by approximately 25%, particularly when the implant shell was bonded. While the tensile strains in the peripheral neck were low in magnitude in the immediate postoperative models, they increased substantially following compressive damage accumulation. Low bone modulus, within the range of normal bone, and high head load contributed the most to large magnitude strains. Therefore, in some cases, hip resurfacing may cause a region of compressive bone damage to develop rapidly, which in turn leads to large tensile strains and potential neck fracture. Our study suggests that indications for surgery should account for bone material quality, and that rehabilitation protocols should avoid high‐load activities. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1319–1325, 2009