Navigation Improves the Survival Rate of Mobile-Bearing Total Knee Arthroplasty by Severe Preoperative Coronal Deformity: A Propensity Matched Case-Control Comparative Study

The primary hypothesis of this study was that the survival rate over 10 years of total knee arthroplasties (TKAs) implanted with a navigation system was superior to that of TKAs implanted with a conventional technique. The secondary hypothesis was that the severity of the initial coronal deformity had a negative influence on the survival rate. A national, multicentric, retrospective study was performed in France, including eight university or private centers with high volumes in knee surgery. Cases operated on with either a conventional (control group) or a navigated (study group) technique were matched after calculating the propensity score using the logistic regression technique. All patients were contacted after 10 years or more to determine the survival of the TKA. The need for date and cause of revision were noted. The primary end point of the study was the occurrence of a revision for any mechanical reason. Survival curves were calculated using the Kaplan-Meier's technique, with the primary criterion as end point. The influence of the implantation technique was analyzed by a log-rank test at a 5% level of significance. The influence of severity of the preoperative coronal deformity was analyzed using the same technique. A total of 513 cases were included in each group. The survival rates after 13 years were 96.5% in the study group and 92.9% in the control group (not significant). There was no significant difference between both groups for the survival rates after 13 years for small deformity (96.0 vs. 97.0%), but the difference was significant for large deformity (97.0 vs. 89.0%, p =0.04). The results suggest that the use of a navigation system, allowing a more consistent correction of the preoperative coronal deformity, thus allows a better long-term prosthetic survival in cases with a large initial coronal deformity. A navigation system should be routinely used in cases of initial coronal deformity greater than or equal to 10degrees, as conventional techniques do not routinely provide satisfactory axial correction in these difficult cases.