Joint line elevation is not associated with mid-flexion laxity in patients with varus osteoarthritis after total knee arthroplasty
- 47 Downloads
Previous cadaver studies showed that the additional bone cuts in the distal and posterior femur and joint line elevation resulted in laxity at mid-flexion after total knee arthroplasty (TKA). However, these results are not always applicable to TKA candidates because the related studies used cadaver knees with no osteoarthritis. It was hypothesized that the joint line elevation results in mid-flexion laxity after TKA in patients with knee osteoarthritis. The purpose of this study was to analyze the relationship between joint line elevation and mid-flexion laxity in patients with knee osteoarthritis.
30 knees with varus osteoarthritis undergoing TKA were evaluated. Two femoral trial component models were prepared: (1) normal model with a thickness of the distal and posterior femoral components of 9 mm, and (2) 2-mm joint line elevation model with a thickness of the distal and posterior femoral components of 9 − 2 = 7 mm. This 2-mm joint line elevation model simulated an additional bone cut in the distal and posterior femur, and joint line elevation, without an additional bone cut. The femoral trial component models were set before implantation and measured the joint gap kinematics using a tensor device through the full knee range of motion.
The differences in joint gap change from 30° to 90° were not statistically significant between the two models. However, the joint line elevation model decreased the joint gap laxity at 120° (p = 0.02) and at 145° (p = 0.01).
This study showed that a 2-mm joint line elevation was not associated with mid-flexion laxity in patients with varus osteoarthritis in the knee. The results of this study differed from the results in previous cadaver studies.
Level of evidence
Therapeutic study, level II, prospective comparative study.
KeywordsTotal knee arthroplasty Joint line Mid-flexion laxity
The authors received no financial support for the research, authorship, and/or publication of this article.
Compliance with Ethical Standards
Conflict of Interest
There is no conflict of interest.
This study was approved by the institutional review board of Osaka City University Graduate School of Medicine (ID number 1280).
All patients provided informed consent.
- 10.Martin JW, Whiteside LA (1990) The influence of joint line position on knee stability after condylar knee arthroplasty. Clin Orthop Relat Res 259:146–156Google Scholar