|Titel på arbejdet
|”Mobile or Fixed Bearing Articulation in TKA? A Randomized Evaluation of Gait Analysis, Implant Migration, and Bone Mineral Density.”
|Michael Kjeldager Tjørnild
|Afdeling / Sted
|Center for Planlagt Kirurgi, Silkeborg / Ortopædkirurgisk afdeling, AUH
|Abstract / Summary
Total knee arthroplasty (TKA) is the standard treatment of the terminal stadium of osteoarthritis in the knee joint. The good results achieved with TKA are based on lasting pain relief, misalignment correction and improved function. For more than 30 years, orthopaedic surgeons have had the choice between a traditional fixed bearing tibial polyethylene (PE) insert design and various designs with mobile bearing tibial PE. Several gait analysis studies have shown the good functional results of TKA with improvements in temporospatial, kinematic, and kinetic measurements. In spite of these improvements, TKA patients still show gait abnormalities. The majority of clinical studies in this field showed no major differences between fixed bearing and mobile bearing articulation designs. The longevity of fixed and mobile bearing articulation designs has been found to be comparable.
Study I validated a new knee-specific software for Dual-energy X-ray Absorptiometry (DXA) scans prior to use in the randomized, clinical trial (Study III). We found cementation to increase the measured bone mineral density (BMD) without negative influence on the reproducibility. Leg rotation around a vertical axis changed the measured BMD; hence careful placement of the leg at follow-up examination was shown to be crucial for good reproducibility. We also compared the knee-specific software to traditional DXA software and found similar performances of the 2 softwares with regard to point typing the implant and the bone edges correctly on DXA scans.
Study III was based on a randomized clinical trial in which the focus points were a comparison of 1) the migration pattern of the 2 tibial articulation types from baseline and up to 12 months’ follow-up assessed by model-based radiostereometric analysis and 2) the BMD in proximity of the tibial implants assessed by DXA scans using the knee-specific DXA software, which was validated in study I. In study III, 50 patients attended a 12 months follow-up (26 FB/24 MB). The FB implants migrated significantly more than the MB implants after 3, 6 and 12 months’ follow-up, but the expected decrease in periprosthetic BMD was similar for both implants.