Skeletal strain and the maintenance of bone mass

Abstract

The mass and orientation of bone tissue at any location within the skeleton is the result of a continued requirement for a loadbearing structure. Changes in this requirement have a rapid and profound effect on bone mass.

However, it has been shown experimentally that only very short periods of bone loading are necessary to prevent this bone loss. This suggests either that the cells responsible for the control of remodelling are immediately and constantly responsive to transient loading events, or that some form of strain memory exists, which provides a persistent stimulus to maintain bone mass. Recent experiments suggest that the load induced reorientation of bone proteoglycan molecules may provide the basis for such a memory.

These findings reinforce the principles that orthopaedic implants must be designed to allow substantial strains to pass through the bone surrounding them, and that an early return to weight bearing is vital after surgery.