Patellofemoral knee pain following total knee arthroplasty. Comparison between adjusted mechanical and inverse restricted kinematic alignment

Objective: The aim of this study was to assess the functional, radiological, and clinical outcomes of patellofemoral joint in patients who had total knee arthroplasty (TKA) without patellar resurfacing for end-stage osteoarthritis using inverse restricted kinematic alignment (irKA) compared to a control group using adjusted mechanical alignment (aMA), both executed with the same implant at the same Institution. The hypothesis was that patients undergoing TKA without patellar resurfacing for end-stage osteoarthritis using irKA would have superior outcomes related to the patellofemoral joint in comparison to a control group using aMA.Methods: A retrospective examination of registries' prospectively obtained from patients who underwent primary TKA at our Institution between 2016 and 2020 was performed. 40 consecutive patients who underwent TKA implant using irKA were compared to a control group of 80 who had undergone adjusted mechanically-aligned TKA. Groups were matched for age and body mass index. Clinical assessment included Visual Analog Scale (VAS), Knee Osteoarthritis Outcome Score (KOOS), Knee Society Score (KSS), and Kujala Knee Score. Standard weight-bearing anteroposterior and lateral view x-rays were used for radiographic evaluation. Patellar height was assessed using Caton-Deschamps (C-D) and Insall index on lateral view films.Results: In comparison to pre-operative status, both groups had postoperative improvements in VAS, KOOS, KSS, and Kujala ratings (p<0.001). Regarding Kujala score, there were no statistically significant differences between the groups (p = 0.68). Insall index and C-D index results were not statistically different across groups (p = 0.02 and 0.74 respectively).Conclusion: Improvements in post-operative clinical and functional outcomes following TKA were associated with either irKA or aMA. There were no discernible changes between the two groups in terms of postoperative patellofemoral discomfort or variations in patellar height.