Investigation into the factors affecting bearing thickness when performing rotating-platform posterior-stabilized total knee arthroplasty.

BACKGROUND: Rotating-platform posterior-stabilized total knee arthroplasty (PS-TKA) has become a commonly used procedure. It has the potential risk of causing mobile-bearing spinout. In our study, we investigated the factors affecting the bearing thickness when performing rotating-platform PS-TKA.

METHODS: This single-arm, prospective, single-hospital cohort study included 100 consecutive patients who underwent rotating-platform PS-TKA between September 2020 and August 2022. We examined the relationship between bearing thickness and several patient characteristics.

RESULTS: The results of the univariate analysis showed that the bearing thickness was significantly associated with weight (risk ratio = 3.4; 95% confidence interval (CI) = 1.1-11.0; P = 0.016) and implant size of the tibia (risk ratio = 3.4; 95% CI = 1.0-11.5; P = 0.030). We performed multivariate analysis regarding the weight and implant size of the tibia. Neither the weight nor the implant size of the tibia was significantly different from the bearing thickness in the multivariate analysis.

CONCLUSIONS: In rotating-platform PS-TKA, body weight and tibia size may affect the bearing thickness. Weight >60 kg and tibial implant size >67 cm may be risk factors for bearing thickening. Therefore, the surgery can be performed better if these risk factors are considered.