Abstract
Background:
This study aimed to compare the biomechanical performance of cups implanted with manual versus robotic reaming, single versus sequential reaming, as well as no screws, 1 screw and 2 screws.
Methods:
A total of 48, 56-mm diameter 3D-printed porous acetabular cups were impacted into separate polyurethane foam bone models reamed with either manual or robotic arm reaming, and either single or sequential reaming techniques. Simultaneous torsion-compression loading yielded torque at failure, angular displacement at failure and torsional stiffness of acetabular cups fixed with either 0, 1 or 2 acetabular screws.
Results:
Overall, torsional stiffness for robotically-reamed cups (both sequential and single) was 45% higher than those reamed via manual instrumentation (3609.0 vs. 2484.6 N·m/rad; p < 0.0001). With increasing number of acetabular screws, the torque at failure (zero screws: 60.1 N·m vs. 1 screw 67.0 N·m vs. 2 screws 97.9 N·m; p < 0.001) and angular displacement at failure (0 screws: 2.0° vs. 1 screw 1.7° vs. 2 screws 5.3°; p < 0.001) increased. There was no difference in the torque, angular displacement at failure or torsional stiffness observed between cups reamed via single or sequential reaming (all p > 0.05). Neither torque nor angular displacement showed differences at failure (all p > 0.05).
Conclusions:
Robotically-reamed cups demonstrated nearly 50% greater torsional stiffness than those reamed manually, suggesting that robotic reaming results in fewer deviations in sphericity, thereby optimising the congruency of the acetabulum-cup interface.
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