DO PATIENTS REGAIN NORMAL GAIT KINEMATICS AND KINETICS AFTER TOTAL KNEE ATHROPLASTY (TKA)?

Abstract

This is a prospective gait laboratory case matched cohort study of patients after total knee arthroplasty.

20 patients who had TKA with a good functional result and a follow-up superior to 2 years were compared with 20 “normal” knees.

The examiners were blinded to the group. A standardized gait analysis was performed, measuring gait kinematics, kinetics and force plate recordings using Motion Analysis computer software.

All patients had a single surgeon and the same brand mobile bearing platform.

The kinematics parameters were identical in both groups

However the dynamic parameters showed a statistically significant difference

At terminal swing and heel strike the operated patients had a 10-degree extension deficit in their gait analysis, despite of the fact that clinically all patients had a full extension with no quadriceps lag.

The coronal plane kinetics of TKA showed valgus moment in stance despite having radiological normal (180° +/−1°) mechanical axis. (p< 0,02)

In the axial plane, all operated patients had an external rotation moment greater than normals. (p< 0,01)

Despite good clinical ROM and quadriceps strength, the TKA demonstrated a lack of extension in early stance.

This may be due to insufficient extension gap at surgery.

The valgus resultant pattern poses a more challenging question:

Are we aiming for the wrong goals in the mechanical axis, or should we consider undercorrection?

Gait analysis of the TKA patients compared to normals demonstrates dynamic differences in relation with the surgical positioning of the implant.