Influence of Cementation Sequence on Screw Fixation Strength in Reconstructed Bone Defects: Experimental...

Cement augmentation is widely used in orthopedic trauma and reconstructive surgery to enhance fixation stability in compromised bone quality, including metastatic lesions, osteoporotic fractures, and segmental bone defects. However, the influence of cementation sequence on screw-cement interface mechanics remains unclear. The objective of this study was to evaluate and compare the effect of cementation sequence on the axial pull-out strength of cancellous screws in a standardized in vitro biomechanical model.

This in vitro biomechanical study compared the pull-out strength of 4-mm cancellous screws using two cementation techniques: Cementation after screw placement (Group 1) and cementation before screw placement (Group 2). Thirty-two samples were prepared using standardized wooden blocks, polymethylmethacrylate bone cement, and cancellous screws. Axial pull-out strength was measured using a universal testing machine.

The mean pull-out strength was significantly higher in Group 1 (1700 N; standard deviation [SD] ± 282.84 N) compared with Group 2 (1450 N; SD ± 305.51 N) (P = 0.023).

Under controlled experimental conditions, cementation performed after screw placement demonstrated significantly higher pull-out strength compared with cementation before screw placement. These findings provide biomechanical insight into screw-cement interface behavior and may assist surgeons in optimizing cement augmentation techniques when stabilizing implants in structurally compromised bone. The results should not be directly extrapolated to complete in vivo fixation constructs.