Arguments between the fixed and mobile bearing UKA

Wanshou Guo MD.
Department of Joint Surgery, China-Japan Friendship Hospital , Beijing, China Advantages of UKA for treatment of varus knee OA is that it can directly deal with the articular lesion, restore the original joint ligament tension, as far as possible to retain the nature joint kinematics .

Both Fixed bearing and mobile bearing UKA can be available for treatment of varus knee OA. Although two types of design show no difference in long term of survivorship, failure model is different due to bearing design futures. Mobile bearing UKA(Oxford), excellent with high congruence , lower polyethylene wear, good kinematics, more accuracy instrumentation, but long learning curve needed, high risk of bearing dislocation. Dislocation, lateral progression of arthritis and aseptic loosening are the major failure reasons for the mobile bearing design. Fixed bearing UKA( M/G or ZUK) with less congruency, but simple procedure, lower incidence of radiolucent line , no dislocation. Lateral progression of arthritis, polyethylene wear, aseptic loosening are the major failure reasons for the fixed bearing design. Several studies comparing these bearing designs suggested no conclusive advantage of one bearing design over another.

Data from CJFH: 437 knee between January 2003- June 2015 were reviewed retrospectively , of these 388 knees had mobile bearing design and 49 knees had fixed bearing design, including Preservation all poly tibia (DePuy):11 keens, M/G(Zimmer): 26 knees, ZUK(Zimmer):12 knees. all UKAs were performed by one surgeon, Follow up: 6 months-14years, 92 male knees vs 345 female knee , 410 knees OA vs 27 knees ON, Mean age : 65.3 years.

UKA Result: Pain was relieved 93%, Mean post-operative ROM of the knees was 123° HSS score was increased from 62 to 92. Mean post-operative Hb : 117g/L, No blood transfusion, VAS score ：Decrease from 7.2 to 2.5 Satisfaction ：87%. Revision: 7 cases. three revised to TKA, one( Oxford knee)duo to infection, two(one Oxford Knee, one( Preservation) duo to aseptic loosening. Four cases(Oxford knee) changed insert for dislocation.

Progression arthritis: two cases, one Preservation. one Oxford after re-implantation of a thicker insert for dislocation. Our data suggested that UKA either fixed bearing or mobile bearing designs can be used for treating varus Knee OA and provide good clinical result.