Abstract
BackgroundWe compared the functional outcome between conventional and high-flexion total knee arthroplasty (TKA) using kneeling and sit-to-stand tests at 1 year post-operative. In addition, the patient’s daily functioning, pain and satisfaction were quantified using questionnaires.MethodsWe randomly assigned 56 patients to receive either a conventional or a high-flexion TKA. Primary outcomes were maximum flexion angle and maximum thigh-calf contact measured during kneeling at 1 year post operatively. Secondary outcomes were the angular knee velocity and ground reaction force ratio measured during sit-to-stand performance tests, and questionnaires.ResultsAt one year post-operative, maximum knee flexion during kneeling was higher for the high-flexion TKA group (median 128.02° (range 108–146)) compared to the conventional TKA group (119.13° (range 72–135)) (p = 0.03). Maximum thigh-calf contact force was higher for the high flexion TKA group (median 17.82 N (range 2.98–114.64)) compared to the conventional TKA group (median 9.37 N (range 0.33–46.58))(p = 0.04). The sit-to-stand tests showed a significantly higher angular knee velocity in the conventional TKA group (12.12 rad/s (95%CI 0.34–23.91); p = 0.04). There were no significant differences between groups in ground reaction force ratios and patient-reported outcome scores.ConclusionAlthough no differences were found in patient-reported outcome scores, differences in performance-based tests were clearly apparent. Standing up from a chair at 90° of knee flexion appeared to be easier for the conventional group. The kneeling test revealed significantly higher weight-bearing knee flexion for the high-flex group. Hence, if kneeling is an important activity for a patient a high-flex design may be recommendable.Trial registrationThe study was retrospectively registered in ClinicalTrials.gov under identifier NCT00899041 (date of registration: May 11, 2009).
Highlights
We compared the functional outcome between conventional and high-flexion total knee arthroplasty (TKA) using kneeling and sit-to-stand tests at 1 year post-operative
Complications In the conventional TKA group, one patient had a deep venous thrombosis treated with anti-coagulants 48 days post-operative, one patient had an inadequate knee flexion post-operatively and was treated with manipulation under anesthesia, and one patient had a patellar clunk and was treated using arthroscopic debridement
Since an infected TKA was explicitly specified as reason for post-randomisation exclusion, and this patient was unable to perform kneeling and stand tests (STS) movements this patient was excluded from the statistical assessment
Summary
We compared the functional outcome between conventional and high-flexion total knee arthroplasty (TKA) using kneeling and sit-to-stand tests at 1 year post-operative. The patient’s daily functioning, pain and satisfaction were quantified using questionnaires. Several types of implant designs have been manufactured in order to optimize the results after total knee arthroplasty (TKA). Range of motion (ROM) is an important outcome parameter of postoperative knee function [1,2,3]. High-flexion designs are aimed at accommodating larger postoperative ROM necessary for activities of daily living (ADL), such as kneeling, standing up from a low chair, sitting cross-legged, transferring in and out of bath, gardening and stair climbing [4,5,6,7,8,9]
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