unicortical screw
A screw that engages only one cortex of bone, typically used when bicortical purchase is not feasible or necessary.
Full Definition
A unicortical screw penetrates through only one cortical layer of bone, in contrast to bicortical screws that engage both near and far cortices. These screws are commonly used in areas where the far cortex is inaccessible, such as near neurovascular structures, or when the bone geometry makes bicortical engagement impossible. While providing less pullout strength than bicortical screws, unicortical screws offer adequate fixation in many clinical scenarios, particularly in metaphyseal bone with good bone quality. The decision between unicortical and bicortical fixation depends on bone quality, fracture pattern, and anatomical constraints.
Usage
Usage note: Always specify unicortical vs. bicortical in operative reports for clarity of surgical technique.
In Context
- "Unicortical screws were used proximally to avoid penetration of the femoral canal." — Operative report
- "The surgeon opted for unicortical fixation to prevent injury to the posterior neurovascular bundle." — Case study