Relationship between intra-operative joint gap and knee flexion angle after posterior-stabilized total knee arthroplasty

Purpose

Conflicting evidence exists about the appropriate intra-operative soft tissue balance in posterior-stabilized (PS) total knee arthroplasty (TKA). The purpose of this prospective observational study was to investigate the impact of intra-operative soft tissue balance on post-operative knee flexion angle.

Methods

A single surgeon performed 164 TKAs using a single brand of PS prosthesis via the subvastus approach without using a pneumatic tourniquet. Intra-operative soft tissue balance was quantified as the gaps between the femoral component and tibial osteotomy surface with the knee flexed at 0°, 30°, 90°, and 120° with the patellofemoral joint reduced. Multiple regression analyses were employed to identify independent predictors of knee flexion angle 1 year after TKA.

Result

The pre-operative knee flexion angle and the gap difference between 120° and 0° flexion were positively correlated with knee flexion angle 1 year after TKA [β ​= ​0.37, 95% confidence interval (CI) 0.26–0.48, P ​< ​0.001; and β ​= ​1.09, 95% CI 0.04–2.14, P ​= ​0.042, respectively]. There was no correlation with knee flexion angle 1 year after TKA for the gap difference between 30° flexion and 0° flexion and between 90° flexion and 0° flexion.

Conclusions

Intra-operative soft tissue balance at 120° flexion may affect the post-operative knee flexion angle in PS-TKA.