Restoration of preoperative tibial alignment improves functional results after medial unicompartmental knee arthroplasty

Abstract

PurposeThe alignment obtained after unicompartmental knee arthroplasty (UKA) inluences the risk of failure. Kinematic alignment after UKA based on Cartier angle restauration is likely to improve clinical outcomes compared with mechanical alignment. The purpose of this study is to analyze the inluence of implant alignment and native knee restoration after UKA using the conventional techniques on clinical outcomes. Methods This retrospective study included 144 medial UKA patients from 2015 to 2020. Radiographic measurements were performed pre-and postoperatively. Outliers were deined as follows: Δ Cartier > 3° (diference between the preoperative and postoperative Cartier angle); Δ MPTA (Medial Proximal Tibial angle) and postoperative TCA (Tibial Coronal component Angle) > 3° (diference between the positioning of the tibial implant and the preoperative proximal tibial deformity). The Knee injury and Osteoarthritis Outcome Score (KOOS), the International Knee Society (IKS) Function and Knee score, the Forgotten Joint Score (FJS), and the Subjective Knee Value (SKV) were evaluated. A Student t test or a non-parametric Wilcoxon test was used for non-normal data to compare pre-and postoperative values for functional scores and angular measurements. The correlation of postoperative angles with functional outcomes was assessed by the Spearman's rank correlation coeicient. Results During the inclusion period, 214 patients underwent medial UKA, 71 patients were excluded, and 19 were lost to follow-up leaving 124 patients with 144 knees (20 bilateral UKA) included for analysis with a mean follow-up of 54.7 months ± 22.1 (24-95). The Δ Cartier was signiicantly correlated with IKS function (R 2 = 0.06, p < 0.001) and FJS (R 2 = 0.05, p < 0.01) scores. The Δ preoperative MPTA-TCA was signiicantly correlated (p < 0.001) with KOOS (R 2 = 0.38), IKS Knee (R 2 = 0.17), IKS function (R 2 = 0.34), SKV (R 2 = 0.08), and FJS (R 2 = 0.37) scores. In subgroup analysis, nonoutliers (< 3°) for Δ preoperative MPTA-TCA had better KOOS score (Δ = 23.5, p < 0.001) and IKS Function (Δ = 17.7, p < 0.001) compared to outliers (> 3°) patients. Conclusion Functional results after medial UKA can be inluenced by implant alignment in the coronal plane with slight clinical improvement when positioning the tibial implant close to the preoperative tibial deformity, rather than by restoring the Cartier angle. This series suggests the interest of a more personalized alignment strategy, but these results will have to be conirmed by other controlled studies. Level of evidence IV, retrospective case series.

CPAK classification detect the real knee joint apex position in less than half of the knees

“…Rosso used MPTA and Mikulicz-Joint line angle as JLO [24]. In our study, the JLOAT measurement was utilised because its clinical effects are well established in the literature and the ICC has been shown to be excellent [18,22]. Our study measurements conducted with LSRs, because of computed tomography (CT) involves high radiation dose.…”

“…KJLO provides both a numerical value and the position of the obliquity (e.g., apex proximal, neutral or distal). It is a reproducible assessment with high interobserver and intraobserver reliability [18] and is considered one of the most reliable methods [5]. The KJLO is not affected by constitutional varus changes, thus providing a more accurate assessment of knee joint inclination [29].…”

A Lightweight Browser-Based Tool for Collaborative and Blinded Image Analysis

“…Tyche is appropriate for standard measurements like length, angle, or area. Machado et al, Micicoi et al, and Schippers et al have already used it on small series (<200 images) for orthopedic measurements [38][39][40]. In addition, with the single-choice question format, Tyche can be efficiently used to score images, like in a study by Schippers et al, which applied the Kallgren and Lawrence score to more than one hundred pelvic X-rays [41].…”