Association between limb alignment and patient-reported outcomes after total knee arthroplasty using an implant that reproduces anatomical geometry

Arata Nakajima,Yasuchika Aoki,Koichi Nakagawa,Masato Sonobe,Toru Suguro,Yorikazu Akatsu,Hiroshi Takahashi

doi:10.1186/s13018-018-1030-8

Abstract

BackgroundA kinematically aligned (KA) total knee arthroplasty (TKA) is expected to improve patient satisfaction, but its effect remains controversial. We investigated differences in patient-reported outcomes (PROs) between KA and non-KA TKAs using an implant that reproduces anatomical geometry.MethodsTKAs for varus deformity were performed in consecutive 129 patients (149 knees) via a measured resection technique with conventional instruments. The femorotibial angle (FTA), hip-knee-ankle angle (HKAA), and the angle between the joint line and the line perpendicular to the mechanical axis (AJLMA) were measured postoperatively (mean 13.6 months), and an AJLMA of ≥ 2° was defined as kinematic alignment. Patients were assigned to two or three alignment categories in each measurement method, and the Knee Society Scores (KSS) and Japanese Knee Injury and Osteoarthritis Outcome Scores (J-KOOS) was compared among the groups.ResultsFor patients assessed by FTA, an ADL-related J-KOOS subscale (J-KOOS-A) showed a significant difference between valgus and varus outliers (p < 0.05). When assessed by HKAA, neither the KSS nor J-KOOS subscales were significantly different among groups. When assessed by AJLMA, J-KOOS-A was significantly different between groups, and a group for AJLMA of ≥ 2° had higher scores than a group for AJLMA of < 2° (95% CI 0.323–7.763; p < 0.05).ConclusionsPatients with an AJLMA of ≥ 2° reported significantly higher patient’s satisfaction regarding ADL. This suggests the importance of restoration of the physiological joint line which can be achieved via KA TKAs.

Highlights

A kinematically aligned (KA) total knee arthroplasty (TKA) is expected to improve patient satisfaction, but its effect remains controversial
None of the Japanese Knee Injury and Osteoarthritis Outcome Scores (J-Knee Injury and Osteoarthritis Outcome Score (KOOS)) subscales were significantly different among groups (Table 3, middle)
The most important findings of the present study were that patients with a postoperative AJLMA of ≥ 2° scored significantly higher in J-KOOS-A than those with a postoperative AJLMA of < 2°, and there were no significant differences in other J-KOOS subscales and the Knee Society Scores (KSS) between groups

Summary

Introduction

A kinematically aligned (KA) total knee arthroplasty (TKA) is expected to improve patient satisfaction, but its effect remains controversial. We investigated differences in patient-reported outcomes (PROs) between KA and non-KA TKAs using an implant that reproduces anatomical geometry. Postoperative restoration of a neutral limb alignment to preserve knee function and longevity has been the primary goal of conventional total knee arthroplasty (TKA) over the past two decades [1, 2]. In general, patients’ satisfaction with TKAs is not as favorable as it is for total hip Recently, kinematically aligned (KA) TKAs were introduced by Bellemans [6]. Little information is available in terms of the postoperative association between the limb alignment and patient-reported outcomes (PROs) in KA TKAs

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