• Erik N Kubiak, Mathew Bong, Samuel S Park, Fred Kummer, Kenneth Egol, and Kenneth J Koval.
• Department of Orthopaedic Surgery, NYU-Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003, USA.
• J Orthop Trauma. 2004 Jan 1;18(1):12-7.

ObjectiveTo compare the screw sliding characteristics and biomechanical stability of four-part intertrochanteric hip fractures stabilized with an intramedullary nail using either one large-diameter lag screw (intramedullary hip screw [IMHS]; Smith & Nephew, Memphis, TN) or two small-diameter lag screws (trochanteric antegrade nail [TAN]; Smith & Nephew, Memphis, TN).DesignLaboratory investigation using eight matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric hip fractures.InterventionOne femur of each matched pair was stabilized with an IMHS intramedullary nail, and the other was stabilized with a TAN intramedullary nail. Femurs were statically, then cyclically loaded on a servohydraulic materials testing machine. Finally, all specimens were loaded to failure.Main Outcome MeasuresScrew sliding and inferior and lateral head displacements were measured for applied static loads from 500N to 1250N. The same measurements were obtained before and after cyclically loading the specimens at 1250N. Ultimate failure strength of the implant constructs also was determined.ResultsThere was no significant difference between the TAN and IMHS in static or cyclical loading with respect to screw sliding or inferior and lateral head displacements. There was a statistically significant difference (P < 0.02) in failure strength, with the IMHS construct failing at an average of 2162N and the TAN construct failing at an average of 3238N.ConclusionThe two constructs showed equivalent rigidity and stability in all parameters assessed in elastic and cyclical tests. The TAN had a greater ultimate failure load.

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