Introduction
Successful press-fit implantation relies on an accurately reamed bone cavity. Inaccurate reaming can lead to a suboptimal press-fit risking fracture and cup deformation or excessive micromotion and loosening. Several factors may impact reaming accuracy including the reamer design, the surgeon’s technique and the bone quality. The aim of this study is to investigate the accuracy of reaming techniques and the accuracy of a novel reamer design.
Methods
Eighty composite bone models, half high-density and half low-density, were reamed with either a conventional or an additively-manufactured reamer with a novel design employing either a straight or ‘whirlwind’ reaming technique. Reamed cavities were scanned using a 3D laser scanner and the median difference between achieved and expected diameters compared.
Results
The novel reamer design was more accurate than the unused conventional reamer, using both whirlwind (0.1mm (IQR 0-0.2) vs 0.3mm (IQR 0.3-0.4); p<0.001) and straight techniques (0.3mm (IQR 0.1-1.0) vs 1.2mm (IQR 1-1.6); p=0.001). Whirlwind reaming was more accurate than straight reaming using both conventional (0.3mm (IQR 0.3-0.4) vs 1.2mm (IQR 1-1.6); p<0.0001) and single use reamers (0.1mm (IQR 0-0.2) vs 0.3mm (IQR 0.1-1.0); p=0.007). Reaming errors were higher in low-density bone compared to high-density bone, for both reamer types and reaming techniques tested (0.6mm (IQR 0.3-1.5) vs 0.3mm (IQR 0.1-0.8); p=0.005).
Conclusion
We present a novel reamer design that demonstrates superior accuracy to conventional reamers in achieving the desired reaming diameter. Improved reaming accuracy was also demonstrated using both devices and in both bone models, using a ‘whirlwind’ technique. We recommend the use of this novel reamer design employing a ‘whirlwind’ technique to optimise reaming accuracy. Particular attention should be paid towards patients with lower bone quality which may be more susceptible to higher inaccuracies.