During plating of a displaced intra-articular distal radius fracture, a lag screw is inserted across the fracture plane. What is the mechanical purpose of the lag technique?

• A To generate interfragmentary compression between the two fragments ✓
• B To neutralise bending forces along the long axis of the bone
• C To bridge the comminuted zone while preserving periosteal blood supply
• D To lock the screw head into the plate and create an angle-stable construct

Explanation

In lag screw technique the thread grips only the far fragment while the near fragment is overdrilled, so tightening draws both fragments together and compresses the fracture interface. This improves stability and aids direct healing. Neutralisation plates resist bending forces, bridging plates span comminution with relative stability, and locking constructs are angle stable by design, none of which describe the lag screw mechanism.

Reference: AO Principles of Fracture Management, 3rd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.