2017 ISAKOS Biennial Congress ePoster #1269

 

The Effect Of Post-Operative Mechanical Axis Alignment On Survival Of Primary Total Knee Replacement After Follow-Up Of 10 Years

Eun-Kyoo Song, MD, PhD, Prof., Gwangju KOREA, REPUBLIC OF
Jong-Keun Seon, MD, PhD, Hwasun, Jeonnam KOREA, REPUBLIC OF
Dong-Hyun Lee, MD, Gwang-Ju KOREA, REPUBLIC OF
Je-Hyoung Yeo, MD, Gwangju KOREA, REPUBLIC OF
Cheng Jin, Fellow, Gwangju KOREA, REPUBLIC OF

Center for Joint Disease, Chonnam National University Hwasun Hospital, Hwasun, Chonnam, KOREA, REPUBLIC OF

FDA Status Cleared

Summary

The neutral limb alignment is an important factor of Total knee Arthroplasty influencing less mechanical axis change and lesser revision rate

Abstract

Introduction

Achieving neutral limb alignment during total knee arthroplasty (TKA) has been identified as a potential factor in long-term prosthesis survival. This study reports the effect of the post-operative mechanical alignment of the lower limb on clinical outcomes and rate of revision TKA due to complication by comparing acceptable mechanical axis group (±3°) and a outlier mechanical axis group where the mechanical axis deviated from neutral by > 3°.

Materials And Methods

Between 2000 and 2007, The prospective study of 334 cases underwent total knee arthroplasty except infection cases. The post-operative mechanical axis (MA) angle was investigated using coronal alignment, evaluated with long-leg radiograph. Deviation of > 3° from the planned position was regarded as an outlier. The evaluation of clinical outcomes at least 8 years follow-up visit included clinical outcomes, such as HHS, KSS pain/function score & WOMAC score. Component survival was calculated by Kaplan-Meier analysis.

Results

286 (85.6%) TKAs was mechanically acceptable group & 48 (14.4%) TKAs was mechanically outlier group. The mean degree change of mechanical axis was greater in outlier group (1.63 ± 2.70 : standard devation) than in acceptable group (0.81 ± 2.43). 26 TKAs were changed from the acceptable group to the outlier group on last follow up. At the time of the latest follow-up, No significance was found for clinical outcomes (HSS, KSS pain/function, WOMAC). In complication, the incidence of aseptic loosening/polyethylene fracture/polyethylene wear/ instability was 2/2/2/4 in acceptable group and 1/0/2/1 in outlier group. 6 of 286 (2.2%) acceptable TKAs were revised whereas 4 of 48 (8.3%) outlier TKAs were revised. There is only significance difference in PE wear compication & revision rate (p=0.031). Kaplan-Meier survival analysis showed a tendency towards improved survival with restoration of a neutral mechanical axis, but this did not reach statistical significance (p=0.247)

Conclusion

This study demonstrates that the neutral limb alignment is an important factor of Total knee Arthroplasty influencing less mechanical axis change and lesser revision rate..