Article ID: JNMS.2020_87-503
Background: In order to restore the neutral limb alignment in total knee arthroplasty (TKA), surgical procedure usually starts with removing osteophytes in varus osteoarthritic knees, however, that the exact influence on alignment correction is unknown. The purpose of this study was to define the influence of osteophyte removal alone on limb alignment correction in the coronal plane in TKA for varus knee.
Methods: Fifteen medial osteoarthritic knees with varus malalignment scheduled for TKA were included in this study. After registration of a navigation system, each knee was tested at maximum extension, and at 30, 40 and 60 degrees of flexion before and after osteophyte removal. External loads of 10 N-m valgus torque at each angle and in both states were applied. Subsequently, the widths of the resected osteophytes were measured.
Results: The average pre-operative hip-knee-ankle angle was -14.2 degrees. The average width of osteophytes was 7.6 mm in femur and 5.3 mm in tibia, respectively. Angle corrections after osteophyte removal were 3.4 degrees at maximum extension, 3.4 degrees at 30 degrees flexion and 3.6 degrees at 60 degrees flexion; and at all angles, the difference was significant. There was positive correlation between the widths of osteophytes and the degree of angle correction at 30 degrees.
Conclusion: Correlation was found at 30 degrees of knee flexion between the widths of osteophytes and the degree of angle correction in the coronal plane in TKA. We found the degree of angle correction per 1mm width of osteophyte removal to be 0.4 degrees.