Bicortical purchase
Screw fixation technique engaging both the near and far cortical bone surfaces for enhanced stability.
Full Definition
Bicortical purchase refers to a screw fixation technique where the screw threads engage both the near (entry) and far (exit) cortical surfaces of a bone, providing superior mechanical stability compared to unicortical fixation. This technique is particularly important in osteoporotic bone, metaphyseal regions, or when maximum pullout strength is required. Bicortical purchase distributes loads across both cortices, reducing the risk of screw loosening or pullout. However, it requires careful measurement and drilling technique to avoid overshooting or creating excessive far cortical damage.
Usage
Usage note: Essential concept for describing screw fixation quality and stability.
In Context
- "All screws achieved bicortical purchase to maximize fixation strength in the osteoporotic bone." — Operative technique description
- "Bicortical purchase was confirmed fluoroscopically before final screw tightening." — Intraoperative documentation