A modified hip screw incorporating injected cement for the fixation of osteoporotic trochanteric fractures.
OBJECTIVE
To evaluate a modified sliding hip screw for the fixation of trochanteric fractures that provides increased fixation strength in osteoporotic bones and allows for the safe intraoperative application of bone cement.


METHODS
Biomechanical cadaver study.


METHODS
Unstable trochanteric fractures were simulated by osteotomy in nine pairs of cadaveric femurs and stabilized by a standard sliding hip screw randomly assigned to the left or right femur. The contralateral femur was stabilized with a newly designed hip screw, which was augmented with low-viscosity bone cement.


METHODS
Femoral bone mineral density was measured by dual x-ray absorptiometry and quantitative computed tomography. Fixation stability of the hip was assessed after dynamic loading by displacement measurement of the femoral head in a simulated one-leg stance configuration.


RESULTS
Modification of the hip screw together with cement augmentation significantly (p < 0.05) increased the initial stability of the fracture fixation technique. The total displacement of the femoral head was reduced by 39 percent on average using cement augmentation in the modified screw compared with the standard sliding hip screw. The largest improvement in initial fixation stability was found for the most osteoporotic bones.


CONCLUSIONS
This modified hip screw augmented with bone cement can significantly enhance the initial fixation stability of trochanteric fractures in osteoporotic femurs.
Augat
Peter
P
Institute of Orthopaedic Research and Biomechanics, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany.
Rapp
Stefan
S
Claes
Lutz
L
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000737:chemistry*; D001863:Bone Screws; D002102:Cadaver; D003720:Densitometry; D004867:Equipment Design; D004869:Equipment Safety; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation / Q000379:methods*; D006620:Hip Fractures / Q000601:surgery*; D006801:Humans; D015552:Injections, Intralesional; D010024:Osteoporosis / Q000150:complications; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D011336:Probability
D001843:Bone Cements; D019904:Polymethyl Methacrylate