A Single Surgeon Series comparing the Outcomes of a Cruciate Retaining and Medially-Stabilised Total Knee Arthroplasty using Kinematic Alignment Principles

Abstract Aims Total Knee Arthroplasty (TKA) designs are developed to optimize kinematics and improve patient satisfaction. The Cruciate Retaining (CR) and Medially-Stabilised (MS) TKA designs have reported good midterm follow up outcomes. However, reasons for consistently high rates of patient dissatisfaction following a TKA remain poorly understood. To further investigate this, we compared the short-term functional outcomes and quality of life, using patient-reported outcome measures (PROMs) and Range of Motion (ROM), between a CR and MS TKA. Methods A prospective comparison was made between 2 groups (44 CR-TKA vs 46 MS-TKA). The KOOS, KOOS-12, KOOS-Shortform, KOOS-JR, Oxford Knee Score, WOMAC, UCLA Activity Scale, and EQ-5D-5L were completed pre-operatively and one year post-operatively. The Forgotten Joint Score (FJS) and VAS-satisfaction were completed at one year post-operatively. ROM was collected pre-operatively and one year post-operatively. Results Patients who underwent an MS-TKA scored significantly better than the CR-TKA on the FJS (MS= 79.87, CR= 63.8, p =.005), the KOOS-12 Quality of Life subscale (MS= 82.8, CR= 74.4, p= 0.43) and the KOOS Quality of Life subscale (MS= 82.8, CR= 74.6, p= 0.44). There was no difference between the groups in all assessed PROMs or ROM, pre-operatively and one year post-operatively. Conclusion Patients who underwent the MS-TKA scored significantly better on the FJS and the quality of life subscale of the KOOS and KOOS-12 than those who underwent a CR-TKA. All other assessed PROMs and ROM were comparable between the two groups and demonstrated that both implants facilitated symptom relief and improved daily function at one year post-operatively. These findings suggest that at short-term follow-up, the MS device is more likely to allow a patient to “forget” that a joint has been replaced and restore their quality of life. Long-term assessment of MS-TKA design outcomes in larger cohorts is recommended.