Advanced functional biomechanical analysis of medial rotation knee arthroplasty

Tawy, Gwenllian Fflur and Rowe, Philip and Biant, Leela (2020) Advanced functional biomechanical analysis of medial rotation knee arthroplasty. Knee, 27 (3). pp. 854-862. ISSN 0968-0160 (

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Background: The Medacta GMK-Sphere total knee arthroplasty (TKA) is designed to mimic the movements and stabilimidty of a natural knee for optimal post-operative function and mobility. This study aimed to quantify the early functional outcome of patients with this implant. Methods: Patients due to undergo TKA to treat end-stage osteoarthritis were recruited into this study. Functional tests of knee range of motion (ROM), strength, and gait kinematics were carried out pre-operatively and one year post-operatively at routine clinics. Motion capture technology and a force transducer were used to collect all data. Normality tests were completed on all data sets to confirm normal distribution of the data, then paired t-tests were used to statistically compare the results. The level of significance was set as α = 0.05. Results: Sixty-three patients underwent pre-operative assessments; of which 30 returned one year post-operatively and consented to have follow-up testing. The operative knee was found to have poorer function than the contralateral knee pre-operatively (p < 0.05). Post-operatively, knee ROM significantly improved on the operative side to a mean of 116.1 ± 19.0. Gait kinematics also improved, especially in the frontal plane, but some abnormal traits remained in the sagittal plane. Knee strength decreased post-operatively. Conclusions: The Medacta GMK-Sphere TKA improves knee range of motion sufficiently within the first postoperative year to allow patients to carry out most activities of daily living (> 110° knee flexion), but continued poor knee strength may limit their abilities to complete tasks which are more biomechanically demanding than walking.


Tawy, Gwenllian Fflur ORCID logoORCID:, Rowe, Philip ORCID logoORCID: and Biant, Leela;