Clinical Validation and Excellent Interobserver Agreement of Volumetric Matching Micromotion Analysis (V3MA) in Total Knee Arthroplasty

CT‐based radiostereometric analysis (CT‐RSA) is an alternative to RSA to measure implant migration. We performed a clinical validation study using VoluMetric Matching Micromotion Analysis (V3MA) software for CT‐RSA. The aims of this study were to assess the agreement between V3MA and Model‐based RSA software (for RSA), and to determine the interobserver agreement in V3MA. On a subset of patients included in a clinical trial, knee prosthesis tibial implant migration was measured between 1 and 5 years postoperative with V3MA and Model‐based RSA software. V3MA and Model‐based RSA results were compared by assessing the mean differences and limits of agreement (mean ± 1.96* standard deviation) using Bland–Altman analysis. V3MA migration results of two observers were compared using intraclass correlation (ICC) and Bland–Altman analysis. Twenty‐four patients were included in the analysis. The mean difference (limits of agreement [LOA]) was −0.14 mm [−0.88 to 0.60] for maximum total point motion (MTPM). LOA for translations and rotations did not exceed ±0.5 mm and ±1°, respectively. The ICC (95% confidence interval) for MTPM between observers was 0.995 (0.989–0.998), and the mean difference [LOA] was 0.04 mm [−0.17 to 0.24]. We showed that between 1 and 5 years postoperative, V3MA migration results were comparable to those of Model‐based RSA for cemented tibial component migration in a clinical study. The interobserver variability showed excellent agreement for V3MA. Overall, V3MA is a valid alternative to Model‐based RSA for the analysis of tibial component migration in TKA with medium‐term follow‐up.