# The Degree of Joint Line Obliquity Change Is Not Associated with Patient Preference in Bilateral Posterior-Stabilized Total Knee Arthroplasties

## TL;DR

This study found that changes in joint line obliquity in knee replacements do not affect patient preference between the two knees.

## Contribution

It shows that JLO change is not a key factor in patient satisfaction with bilateral posterior-stabilized knee replacements.

## Key findings

- Patients showed no significant preference for knees with greater or smaller JLO changes.
- JLO preservation may not be crucial for patient satisfaction in PS TKAs.
- No differences in patient-reported outcomes were found between the two knee types.

## Abstract

Objectives: To evaluate patient reference in paired bilateral posterior stabilized (PS) total knee arthroplasties (TKAs) with significantly different degrees of joint line obliquity (JLO) change. Methods: A retrospective review was conducted on 128 patients who underwent paired bilateral PS TKAs, with greater and smaller JLO changes (G-ΔJLO and S-ΔJLO knees; a side-to-side difference in JLO change >3° between G-ΔJLO and S-ΔJLO knees). The mean follow-up period was 3.9 years (minimum 2 years). Radiographic changes in JLO were measured according to the Coronal Plane Alignment of the Knee (CPAK) classification. Maintenance of the CPAK type and JLO direction (apex distal, neutral, and apex proximal) was investigated. Clinically, the preferred TKA out of greater and smaller JLO changes was investigated. The Hospital for Special Surgery and Western Ontario and McMaster Universities Osteoarthritis Index were evaluated. Results: The average JLO change was 10.5° in the G-ΔJLO knees and 5.5° in the S-ΔJLO knees (p < 0.001). The CPAK type and JLO direction was better maintained in the S-ΔJLO knees (p < 0.001, respectively). Regarding preference, 40 patients (31.2%) were satisfied with bilateral TKAs without a specific preference, while 44 patients (34.3%) preferred TKAs of the G-ΔJLO knee and 44 patients (34.3%) preferred the S-ΔJLO knee (p = 1.000). No significant differences were found in the patient reported outcomes between the G- and S-ΔJLO knees. Conclusions: The degree of joint line obliquity change was not associated with patient preference in bilateral PS TKAs. JLO preservation may not be a critical determinant of patient preference in PS TKA.