Surgical Tech Practice Exam: Free Practice Test & Study Guide

The correct answer is the lag screw, as it is specifically designed to compress bone fragments together, facilitating the healing process after fractures or surgical repairs. The lag screw achieves this compression by utilizing a technique where the screw is partially threaded, allowing the screw head to pull the fragments tightly together as it is tightened. This type of screw is particularly effective in providing stability and alignment in various orthopedic and surgical contexts, making it an essential tool for achieving optimal outcomes in bone repair.

The other screw types listed serve different purposes. The set screw is generally used to secure parts in place without necessarily providing the same compressive force that a lag screw does. A cancellous screw, while it does engage with the trabecular bone and provides purchase, is primarily focused on holding fragments together rather than compressing them. Lastly, a drain screw is typically utilized in applications involving drainage systems, rather than in the direct fixation or compression of bone. Thus, when considering the aim of compressing bone fragments specifically, the lag screw is the most appropriate choice.