Intraoperative Navigation-Based Laxity Measurements and Long-Term Outcomes After Total Knee Arthroplasty: A Retrospective Cohort Study

The available literature provides limited and inadequate data regarding the association between intraoperative knee kinematics, long-term clinical outcomes and survivorship after total knee arthroplasty (TKA). This study aimed to examine the potential relationship between specific intraoperative kinematics laxity assessment, acquired with a computer navigation system, and the long-term clinical outcomes and survivorship in patients undergoing TKA. This study consists of a retrospective cohort analysis of consecutive TKA procedures, in which a surgical navigation system was utilized to intra-operatively assess bone resections, implant positioning and gap balancing. The intraoperative kinematic parameters included varus-valgus laxity at 0° (VV 0) and 30° of flexion (VV 30), anterior–posterior displacement at 90° of flexion (AP 90), and passive range of motion (ROM). Different prosthesis designs were used, with a predominance of the posterior stabilized (PS)-type implant. The Knee Injury and Osteo-arthritis Outcome Score (KOOS) was used to investigate patients’ clinical and functional status. Survival was analyzed with the Kaplan–Meier method. Between-group comparisons were performed using the Mann–Whitney U test. A univariate logistic regression analysis was conducted to identify factors associated with clinical failure. Of 165 eligible patients, 120 were included in the final analysis, with a mean follow-up of 7.7 ± 2.8 years. Revision surgery was required in seven cases, representing surgical failure and an overall survival rate of 94.2%, with survival probabilities of 98.8%, 97.4%, and 93.6% at 6, 8, and 10 years, respectively. Clinical failure (KOOS < 70 in three domains) occurred in 23 patients. No intra-operative surgical parameters, including Hip-Knee-Ankle angle, Preoperative KL grade, prostheses design, VV 0, VV 30, AP 90 and ROM, or demographic variables, were found to be statistically correlated with clinical failure at follow-up. Although, in this navigated TKA cohort, survivorship was acceptable and consistent with previously reported benchmarks, it was not possible to reliably predict survival probability based solely on the intra-operative laxity parameters measured. Nevertheless, the use of surgical navigation can help surgeons accurately assess bone resections and the balance of prosthetic components.