Femoral nailing through the trochanter: the reamer pathway indicates a helical nail shape.

Objectives: This biomechanical study captured the reamer pathway in human femurs reamed through a greater trochanteric entry portal. The spatial pathway of the reamed intramedullary canal was analyzed to determine how closely a helix can match the dimensions of this canal.

Methods: Twenty-one human cadaveric femurs were reamed through a trochanteric entry portal 12 mm lateral to the superior trochanteric border.

Lag screws for hip fracture fixation: Evaluation of migration resistance under simulated walking.

Previous mechanical studies concerning cut-out of lag screws for pertrochanteric hip fractures have relied on static or dynamic uniaxial loading regimens to induce construct failure by varus collapse and superior cut-out. However, the hip is loaded in a multiplanar, dynamic manner during normal gait. We designed a hip implant performance simulator (HIPS) system to evaluate lag screw cut-out under multiplanar loading representative of normal gait.

Depth-dependent strain of patellofemoral articular cartilage in unconfined compression.

This biomechanical study reports strain gradients in patellofemoral joint cross-sections of seven porcine specimens in response to 1% unconfined axial compression subsequent to specific amounts of off-set strain. Strain distributions were quantified with a customized laser-based electronic speckle pattern interferometry (ESPI) system in a non-contact manner, delivering high-resolution, high-sensitivity strain maps over entire patellofemoral cartilage cross-sections. Strain reports were evaluated to determine differences in strain magnitudes between the superficial, middle, and deep cartilage layers in femoral and patellar cartilage.

A laboratory model to evaluate cutout resistance of implants for pertrochanteric fracture fixation.

Objectives: To establish a laboratory model of implant cutout, which can evaluate the effect of implant design on cutout resistance in a clinically realistic "worst case" scenario.

Setting: Orthopaedic biomechanics laboratory.

Design: Implant cutout was simulated in an unstable pertrochanteric fracture model, which accounted for dynamic loading, osteoporotic bone, and a defined implant offset.