The Medoff sliding plate and a standard sliding hip screw for unstable intertrochanteric fractures: a mechanical comparison in cadaver femurs.
The Medoff sliding plate has a dual side capability along both the femoral shaft and neck to increase theoretically interfragmentary compression and load-sharing in hip fractures. We studied intertrochanteric fracture fixation in cadaveric bone to determine whether this device has a mechanical advantage over a standard sliding hip screw. 2-part and 4-part fractures were created in 12 cadaver femurs. The fractures were fixated and sequentially destabilized; bone and plate strains and fragment displacements were determined during testing, as a function of applied physiological loads before and after short-term cycling. The Medoff sliding plate imposed a higher mean medial cortex strain than the sliding hip screw in all fracture models and at all loading levels, and the difference was statistically significant in the 2-part and in the unstable 4-part fracture models. The loading of the medial cortex region after cycling was approximately 50% higher in the Medoff samples than in the sliding hip screw samples. There were no significant differences in plate strains, fracture displacements or load to failure between the 2 devices. These observations favor the dual sliding principle as regards providing fracture compression and load-sharing, which may explain low failure rates in clinical series of unstable intertrochanteric fractures, treated with the Medoff sliding plate.
Department of Orthopedics, Helsingborg Hospital, Sweden.
O
O
Olsson
F J
FJ
Kummer
L
L
Ceder
K J
KJ
Koval
S
S
Larsson
J D
JD
Zuckerman
D000368:Aged; D001696:Biomechanical Phenomena; D015519:Bone Density; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D004867:Equipment Design; D004868:Equipment Failure; D005264:Femoral Fractures / Q000601:surgery*; D005269:Femur / Q000503:physiopathology / Q000601:surgery; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D066298:In Vitro Techniques; D009068:Movement; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013718:Tensile Strength; D016474:Weight-Bearing