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

Abstract

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°.

Factors Influencing Knee Flexion Range of Movement after Primary Total Knee Arthroplasty : Study of a Consecutive Series over Ten Years

“…But, knees are still manipulated for stiffness after total knee replacement [14,23]. The posterior tibial slope does not influence knee flexion [24], the pre anesthetic flexion is the best [25] and thus, pre operative physiotherapy is to be proposed from these observations in our study, like in the recomandiations formulated by Diane UJ and al. in 2020 [26].…”

Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?

“…However, as mentioned previously, many factors influence ROM after TKA as well as other outcomes. We, therefore, referred to the methodology of the study by Ruangsomboon et al [ 21 ], appropriately controlling for all potential confounding factors, with the aim of investigating the association between different FPFAs and the early efficacy of treatment in patients undergoing TKA.…”