New mobile-bearing TKA with unique ball and socket post-cam mechanism offers similar function and stability with better prosthesis fit and gap balancing compared to an established fixed-bearing prosthesis

摘要

PurposeA mobile-bearing (MB) posterior-stabilized total knee arthroplasty (TKA) system with ball and socket post-cam mechanism has been developed with the aims of better prosthesis fit and enhanced stability. However, the data are limited to compare its clinical outcomes with an already established fixed-bearing (FB) implant design.MethodsThis is a prospective randomized study comparing 260 patients in the MB group and 133 patients in FB group with a minimum 2 years of follow-up. Intraoperative variables, post-operative functional outcomes and incidence of adverse events were compared.ResultsMB group showed better prosthesis fit as the incidence of over-hang of femoral component at junction (medial: 1% vs. 5% and lateral: 2% vs 4%, p<0.001) and trochlea (medial: 2% vs 30%, p=0.042 and lateral: 13% vs 21%, p=0.015) was less than FB group. MB group also showed better gap balancing as the incidence of medio-lateral gap difference more than 2mm was less in flexion (2.3% vs. 16%, p<0.001) and extension (3.1% vs. 9.8%, p=0.005). Post-operative functional outcomes and incidence of adverse events showed no difference between the two groups at 2 years.ConclusionsNew MB design offers similar functional outcomes and stability along with better intraoperative prosthesis fit and gap balancing compared to an established fixed-bearing design. Hence, this new MB design could be an alternative prosthesis of choice for posterior-stabilized TKA.Level of evidenceI.