Fixation strength at the interface between Kerboull-type plate and bone cement.

PURPOSE To evaluate the fixation strength at the interface between the Kerboull-type plate and bone cement in 6 experimental conditions. METHODS Experimental materials comprised a simulated acetabular block, a simulated Kerboulltype plate, a pressuriser cover, a pressuriser arm, and bone cement. The simulated Kerboull-type plate was placed on the simulated acetabular block, with the pressuriser cover. Bone cement was added and the pressuriser arm was inserted. After 6 days of curing, pulling tests were performed to measure the fixation strength at the interface between the plate and the bone cement. Six experimental conditions were evaluated. In condition 1, a 1-mm plate was used with no gap between the plate and the acetabular block. In condition 2, a 2.5-mm plate was used with no gap. In condition 3, a 2.5-mm plate was used with a 2-mm gap. In condition 4, the plate was not used. In condition 5, condition 2 was tested with the model rotated 45º. In condition 6, condition 3 was tested with the model rotated 45º. RESULTS The maximum fixation strengths in conditions 1, 2, 3, 5, and 6 were 44.4 N, 59.1 N, 122.5 N, 86.9 N, and 185.2 N, respectively. The most important factor affecting the maximum fixation strength was bone cement at the interface between the plate and the acetabular block, followed by 45º rotation during testing, and then thickness of the plate. CONCLUSION To enhance fixation of the Kerboull-type plate with cemented acetabular cup, penetration of cement into the outer side of the Kerboull-type plate should be minimised.