The pre-anesthetic period is the best time to evaluate the knee flexion angle for predicting the flexion angle after total knee arthroplasty: A prospective cohort study.

INTRODUCTION: Knee flexion angle (KFA) is one of the most critical factors for evaluating patient functional outcomes after total knee arthroplasty (TKA). Preoperative KFA and intraoperative drop leg test are both accepted as predictors of postoperative KFA after TKA. Preoperative testing performed after anesthesia helps overcome pain-related limitations; however, the KFA measurement timepoint that best predicts KFA at 6 months after TKA has not yet been established. METHODS: This prospective cohort study recruited patients who underwent unilateral primary TKA at Siriraj Hospital (Bangkok, Thailand) during August 2012 to August 2017. We recorded KFA at the pre-anesthetic phase, post-anesthetic phase, intraoperation using drop leg test, and at 6-months post-operation. Pearson's correlation coefficient was used to evaluate correlation between different measurement timepoints and 6 months after surgery. Those same relationships were evaluated for overall patients, and for patients with KFA <90° (poor KFA), 90-120° (average KFA), and >120° (high KFA). RESULTS: A total of 165 patients with a mean age of 68.7 years were recruited. Pre-anesthetic KFA measurement had the highest positive correlation with the 6-month KFA (r = 0.771, p<0.05). Post-anesthetic measurement and intraoperative drop leg KFA measurement had moderate positive correlation (r = 0.561, p<0.05) and low positive correlation (r = 0.368, p<0.05) with the 6-month KFA, respectively. The average KFA group had the highest positive correlation between pre-anesthetic KFA measurement and the 6-month KFA (r = 0.711, p<0.05). Predicted 6-month KFA (degrees) adjusted for pre-anesthetic KFA is 45.378 + [0.596 x pre-anesthetic KFA (degrees)] (r = 0.67, p <0.05). CONCLUSIONS: Pre-anesthetic KFA demonstrated the highest correlation with the final KFA at six months after unilateral primary TKA, especially in the patients who had a preoperative KFA within 90-120°.

Results for the mobile-bearing rotating platform knee: minimum 10-year follow-up.

BACKGROUND: The mobile bearing knee was introduced in 1977. Since then, many reports have examined the long-term results obtained with the mobile bearing knee. Some authors reported significant improvement results and longevity for the mobile-bearing knee over the fixed-bearing knee, but some authors reported no significant improvement over the fixed-bearing knee. Many reports have examined the longevity and functional outcomes in patients treat with the mobile-bearing knee. The longest follow-up was 20 years follow-up, but no study has examined long-term outcomes in Thailand. Our study reports the long-term results obtained with a mobile-bearing knee LCS system after at least 10-years of follow-up. OBJECTIVE: To study the long-term results achieved with a mobile-bearing knee LCS system after at least 10-years of follow-up. MATERIAL AND METHOD: The twenty-one patients were included in this prospective-cohort study. Range of motion, patellar score, American Knee Society scores and the radiographic evaluation. Patients were evaluated at pre-operatively and 6 months, 1 year, 5 years, 10 years after surgery. RESULTS: After at least 10 years of follow-up, eighteen patients showed no signs of radiographic loosening. The patellar score, knee score and functional score decreased over time. However, the patellar score increased significantly compared with preoperative values. Only two patients underwent patellar resurfacing, the scores were similar to those reported in other studies at 5 years after surgery. This trend was also observed for the knee score, although it was not significant. This same trend was observed for the functional score and was significant at 10 years after surgery. CONCLUSION: The mobile-bearing rotating platform knee achieves a good knee score and fair functional score after 10 years follow-up. Additional multi-center studies will be necessary to collect more data.