A model of an unstable femoral neck fracture was used in this study to compare the axial and torsional displacement obtained when the neck was fixed by a compression hip screw (CHS) and side plate, or three Knowles pins. Six paired, embalmed femora were mounted on a special, custom-made jig that grasped the femoral head and shaft securely. A standardized osteotomy was made with an oscillating saw, bisecting the distance between the lower cartilaginous portion of the femoral head and the intertrochanteric line. A 5-mm thick slice of bone was excised from the posteromedial quadrant of the distal fragment. The right or left femur in each pair was then randomly assigned to internal fixation with either three Knowles pins or a keyed CHS plus a 130 degrees four-hole side plate. After potting of the specimens and application of rosette strain gauges, axial displacements were measured during the application of in-plane and out-of-plane compressive loads. The resistance to torsion was also determined. There were no statistical differences between the two devices for compressive or torsional loading using this model.
View details for PubMedID 1556626