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 fem oral shaft and neck to increase theoretically interfragmentary compres sion and load-sharing in hip fractures. We studied intertrochanteric f racture fixation in cadaveric bone to determine whether this device ha s a mechanical advantage over a standard sliding hip screw. 2-part and 4-part fractures were created in 12 cadaver femurs. The fractures wer e fixated and sequentially destabilized; bone and plate strains and fr agment displacements were determined during testing, as a function of applied physiological loads before and after short-term cycling. The M edoff sliding plate imposed a higher mean medial cortex strain than th e 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 sample s than in the sliding hip screw samples. There were no significant dif ferences in plate strains, fracture displacements or load to failure b etween the 2 devices. These observations favor the dual sliding princi ple as regards providing fracture compression and load-sharing, which may explain low failure rates in clinical series of unstable intertroc hanteric fractures, treated with the Medoff sliding plate.