INTRAOPERATIVE ROBOTIC ASSESSMENT OF PATELLAR TRACKING IN TOTAL KNEE ARTHROPLASTY: DOES IT PROVIDE ANY ADDITIONAL BENEFIT?

Purpose This study aimed to determine the clinical utility of a novel robotic assessment of patellar tracking in TKA. Patellar tracking patterns in osteoarthritic knees were examined to assess the relationship with coronal alignment, as well as investigate correlation of coronal and sagittal tracking of implanted patellae to early patient outcomes. Methods A retrospective analysis was performed on 252 knees that underwent robotic-assisted primary total knee arthroplasty (TKA). Intraoperative patellar tracking was assessed prior to any bone cuts and after trial implantation, using a previously described technique with the CORI robotic system. Preoperative full-length standing radiographs were used to assess coronal alignment parameters, and knees classified according to the CPAK classification. Associations between patellar tracking patterns and radiographic parameters were analyzed. For a smaller subgroup (103 knees) the relationship between coronal and sagittal PF tracking and early (3 month) pain outcomes was analysed. Results The mean age of the cohort was 71.4 ± 7.1 years. Pre-implantation patellar tracking was classified into three patterns: central tracking in 58% (n = 147), lateral tracking in 35% (n = 89), and medial tracking in 7% (n = 16). A significant association was observed between CPAK alignment category and coronal patellar tracking pattern (p = 0.006). Central tracking was more frequently associated with varus alignment, whereas lateral tracking showed a relative predominance in neutral-to-valgus alignment, reflected by lower mLDFA and higher aHKA and mHKA values (p < 0.05). Sagittal tracking analysis post implantation showed higher pain scores in understuffed PFJ, whereas no correlation was found between coronal tracking post implantation and pain scores. Conclusion Three distinct native coronal patellar tracking patterns were identified using robotic intraoperative assessment prior to implantation. Tracking patterns were associated with coronal alignment characteristics and with broad CPAK alignment categories (varus, neutral, valgus), but not with individual CPAK phenotypes. Sagittal but not coronal tracking had correlation to early pain scores. Robotic assessment of patellar tracking needs further study to better understand its utility, but the early experience suggests it provides a more comprehensive analysis of PF dynamics that may help better inform surgical technique and implant design