Fewer femoral rotational outliers produced with CT- than with MRI-based patient-specific instrumentation in total knee arthroplasty.

purposePrevious studies comparing the surgical accuracy between computed tomography (CT)- and magnetic resonance imaging (MRI)-based patient-specific instrumentation (PSI) methods have produced contradictory results. The aim of this study was to determine which is the more reliable imaging method (CT versus MRI) for patient-specific total knee arthroplasty (TKA). CT-based PSI is hypothesised to have an advantage regarding the number of outliers.

methodsA total of 22 randomised controlled trials (RCTs), including 1749 TKA cases, were eligible for the meta-analysis. RCTs, systematic reviews and meta-analyses on this topic published in databases before September 2018 were identified by a literature search. The primary outcome was the number of lower extremities with greater than 3° of difference in alignment angles between the postoperative outcomes and target outcomes. The parameters calculated from the meta-analysis included risk ratios (RRs) and 95% confidence intervals (CIs). Additionally, the publication bias and heterogeneity of the studies were assessed.

resultsThe risk of femoral rotational outliers in the PSI group (RR = 0.48; 95% CI 0.24-0.98) was significantly reduced. Furthermore, subgroup analysis showed that the accuracy in the CT-based PSI group was significantly higher than that in the MRI-based CSI group (RR = 0.31; 95% CI 0.10-0.92).

conclusionThis meta-analysis shows that when performing TKA with PSI, preoperative CT is beneficial for the production of the PSI, resulting in a significantly lower proportion of outliers in femoral rotational alignment. CT should be the preferred choice for imaging when performing TKA surgery with PSI to obtain better femoral rotational alignment. LEVEL OF EVIDENCE: Therapeutic study (systematic review and meta-analysis), Level I.