Effects of distal radius bone graft harvest on the axial compressive strength of the radius

The effect of metaphyseal cancellous bone graft harvest on distal radius compressive strength is unknown. The purpose of this study was to analyze, in a cadaveric model, changes in distal radius axial compressive strength after distal radius metaphyseal cancellous bone graft harvest.

We randomized 15 matched pairs of cadaveric radiuses into 2 groups. In group I, a target harvest of 25% of the total metaphyseal cancellous bone volume was attempted through a standardized oval cortical window. In group II, a target of 50% harvest was attempted. The study specimens and their matched controls from the contralateral side were loaded to failure in axial compression. The amount of bone graft harvested was calculated. The resulting ultimate loads to failure were measured, then expressed as ultimate stress (millipascals--MPa). We analyzed data for the 2 groups and the matched controls using paired Student's t-tests.

A smaller amount of bone was harvested than anticipated in both groups. The final average distal radius bone graft harvest for group I was 10%, and for group II, 22.5%. Group I had no statistically significant difference in ultimate stress compared with the contralateral specimens that acted as matched controls (p = .273). Group II had a statistically significant decrease in ultimate stress values compared with matched controls (p = .002). The ultimate stress of group I averaged 92.67% of its matched control, whereas the ultimate stress of group II was 74.8% of its matched control (p = .027).

A significant decrease in distal radius ultimate stress occurs when approximately 23% of the metaphyseal cancellous bone is removed through a standardized oval cortical window. When the distal radius is chosen as the bone graft harvest site, we recommend harvest of less than 25% of the total available distal radius metaphyseal cancellous bone to prevent alteration of the load characteristics of the bone.