Cortical | 合法醫療器材資訊網

2019年3月18日—Acancellousbonescrewhaslargerthreadsandahigherpitchincomparisontothecorticalscrew.Itresemblesamodifiedwood-typescrew.

A cancellous bone screw has larger threads and a higher pitch in comparison to the cortical screw. It resembles a modified wood-type screw. It does not have a tapered tip. The core diameter, that is smaller than that of the shaft, offers a greater surface area for the purchase of the screw threads on the bone. A rise in the thread diameter of a cancellous screw raises its pull-out strength. A cancellous screw is inserted into a pilot hole that is untapped. The dimensions of the pilot hole equals the screw’s core diameter. Its big threads form companion threads in the bone by compression as well as by deforming the bone trabeculae. The spring reaction originates from the cancellous bone as the deformation occurs during the thread forming procedure.

The cortical bone screw is a machine-type screw. The threads are smaller (in diameter) and have a lower pitch. The core diameter is relatively large as well a...