Dynamisation of screws means deliberately allowing controlled axial movement/compression at a fracture site after fixation, so that loading and weight bearing promote bone healing.

Most commonly, this refers to an interlocking intramedullary nail that was initially locked with screws at both ends:

Purpose: to stimulate callus formation in a delayed union by reducing the construct’s axial stiffness and bringing fracture surfaces closer together.

Example: A femoral or tibial shaft fracture fixed with a statically locked nail has slow healing. The surgeon may remove a locking screw at the appropriate end of the nail, allowing controlled compression across the fracture.

Important risk: if there is inadequate callus, marked comminution, or poor cortical contact, dynamisation can cause excessive shortening, malalignment, or rotational instability. It must therefore be selected case by case. Rockwood notes that nail dynamisation is commonly accomplished by screw removal or use of a dynamic locking slot, often considered for delayed union after roughly 3-6 months depending on callus quality. Rockwood and Green's Fractures in Adults, 10th ed., delayed union/nonunion section.

A 2025 systematic review also assessed nail dynamisation for delayed/nonunion of femoral and tibial fractures (PubMed record).