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Advanced functional biomechanical analysis of medial rotation knee arthroplasty
Gwenllian Fflur Tawy1, Philip Rowe2, Leela Biant3
1The Division of Cell Matrix Biology & Regenerative Medicine, University of Manchester, Stopford Building, 99 Oxford Road, Manchester M13 9PG, United Kingdom; The Department of Biomedical Engineering, University of Strathclyde, Wolfson Centre, 106 Rottenrow, Glasgow G4 0NW, United Kingdom.
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.
