Abstract
Introduction
Outcomes following large joint arthroplasty are influenced by the accuracy of implant placement. Patient specific (PS) technology has been used in knee arthroplasty surgery however, its application in total hip arthroplasty remains relatively unexplored.
Aims
We investigated whether conventional or PS guides, resulted in a more accurate reconstruction of the pre-operative head centre position.
Methods
A pilot study, determined a minimum of 7 samples were required per group to ensure an adequately powered study. However in order to account for potential errors, ten specimens were prepared for both groups by a single surgeon and using a standardised operative technique. Both groups used instruments, available on standard operating sets, however PS guides were only used and available for the PS group. Following surgery, specimens were laser scanned to generate 3- dimensional surface models. These were then compared to models of a pre-operative specimen. The distance between the pre and post- operative femoral head centres (head position error) was then calculated.
Results
This study analysed 19 implanted specimens, as one specimen was excluded due to an error in preparation. The median and range head position error was 8mm (3.5–10.3) in the conventional group and 3.9mm (2.2–7.4) in the PS group. This difference was statistically significant (U=8.5, z=−2.983, p=0.003).
Discussion
We found that the use of PS guides halved the average head position error and reduced the range of errors. A difference of 4.1mm in head centre position was both statistically and clinically significant.
Conclusions
PS technology improves the accuracy of hip arthroplasty surgery in a dry bone model. It would be reasonable for future studies to further assess the use of PS guides in vivo as part of a clinical trial.
