Patient specific instrumentation associated with less operating time for total knee arthroplasties

1. Total knee arthroplasties (TKAs) done with patient specific instrumentation (PSI) were associated with less OR time and fewer instrument trays used, compared to TKAs done with conventional instrumentation.

2. There were no differences in patient-reported pain and function, or differences in radiologic alignment, when comparing TKAs done with PSI versus conventional instrumentation.

Evidence Rating Level: 2 (Good)

Total knee arthroplasty (TKA) is the gold standard treatment for patients with severe knee osteoarthritis (OA). However, an estimated 20% of patients receiving TKAs are satisfied with the results, with some experiencing pain and limited function. Malalignment may be one cause of this dissatisfaction, and new technologies have been developed to better individualize TKAs, This includes the use of patient-specific instrumentation (PSI), which involves the development of patient-specific cutting guides based on imaging of the patient’s knee. However, it is unclear if the use of PSI affects patient outcomes after TKAs. Therefore, this non-randomized controlled trial aimed to compare patient-reported outcomes, radiologic alignment, and economic factors, amongst individuals undergoing TKA with and without the use of PSI. This study was conducted at 3 centres in Germany, with patients being operated on using PSI and conventional instrumentation in a consecutive manner. Patient-reported outcomes were measured at 6 weeks, 6 months, and 12 months post-op, and included VAS pain score and the Oxford Knee score, which measures knee function. Economic outcomes measured include total OR time (including set-up) and number of instrument trays. In total, there were 139 patients, with 69 undergoing surgery with PSI and 70 with conventional instrumentation. The study found no differences between the two groups in pain scores or Oxford Knee scores, at any of the measured time points. As well, there was no difference in radiologic alignment, with 80.9% of PSI patients and 65.7% of conventional instrumentation patients being within 3 degrees deviation from neutral (p = 0.055). However, the mean total OR time was lower in the PSI group (91.4 compared to 97.1 minutes, p = 0.035), and the median number of instrument trays was also lower in the PSI group (6 compared to 7 trays, p < 0.001). Overall, this study demonstrated that TKAs done with PSI were not associated with significant differences in patient-reported outcomes or radiologic alignment, but were associated with improved economic factors, including less OR time and fewer instrument trays.

Click to read the study in PlosONE

Image: PD

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