Prediction of torsional failure in 22 cadaver femora with and without simulated subtrochanteric metastatic defects: a CT scan-based finite element analysis.
BACKGROUND
In metastatic bone disease, prophylactic fixation of impending long bone fracture is preferred over surgical treatment of a manifest fracture. There are no reliable guidelines for prediction of pathological fracture risk, however. We aimed to determine whether finite element (FE) models constructed from quantitative CT scans could be used for predicting pathological fracture load and location in a cadaver model of metastatic bone disease.


METHODS
Subject-specific FE models were constructed from quantitative CT scans of 11 pairs of human femora. To simulate a metastatic defect, a transcortical hole was made in the subtrochanteric region in one femur of each pair. All femora were experimentally loaded in torsion until fracture. FE simulations of the experimental set-up were performed and torsional stiffness and strain energy density (SED) distribution were determined.


RESULTS
In 15 of the 22 cases, locations of maximal SED fitted with the actual fracture locations. The calculated torsional stiffness of the entire femur combined with a criterion based on the local SED distribution in the FE model predicted 82% of the variance of the experimental torsional failure load.


CONCLUSIONS
In the future, CT scan-based FE analysis may provide a useful tool for identification of impending pathological fractures requiring prophylactic stabilization.
Spruijt
Sander
S
Department of Orthopaedics, Sint Maartenskliniek, Nijmegen, The Netherlands. s.spruijt@maartenskliniek.nl
van der Linden
Jacqueline C
JC
Dijkstra
P D Sander
PD
Wiggers
Theo
T
Oudkerk
Mathijs
M
Snijders
Chris J
CJ
van Keulen
Fred
F
Verhaar
Jan A N
JA
Weinans
Harrie
H
Swierstra
Bart A
BA
D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D002102:Cadaver; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D005266:Femoral Neoplasms / Q000150:complications / Q000473:pathology / Q000556:secondary*; D005592:Fracture Fixation; D005598:Fractures, Spontaneous / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011379:Prognosis; D012307:Risk Factors; D014057:Tomography, X-Ray Computed