2026 · Journal of Arthroplasty
ロボット支援rKA TKAで、アライメント変化と術中内外側ギャップは1–2年の患者報告アウトカムとどう関連するか？
HKAとLDFAの変化が小さいほど、2年時のKnee Society Knee Scoreが高値でした（P = 0.001、0.013）。
研究構造
- 01対象
RKAプロトコルで実装されたTKA 69クロスストレージロボットアシスト.
- 02方法
後ろ向きコホートで、ロボット記録の伸展・屈曲内外側ギャップと、深層学習測定の術前後HKA・LDFA・MPTAを解析しました。多変量ANCOVAとROC解析で1–2年PROMとの関連を評価しました。
- 03報告された結果
HKAとLDFAの変化が小さいほど、2年時のKnee Society Knee Scoreが高値でした（P = 0.001、0.013）。
研究対象・方法・結果を分けて示した説明用の模式図です。論文の原図ではありません。
抄録の解説
対象と方法
主な結果
手術に関する読書のポイント
解釈の限界
簡単に説明しましょう
この研究で何が確認されましたか?
HKAとLDFAの変化が小さいほど、2年時のKnee Society Knee Scoreが高値でした（P = 0.001、0.013）。
治療決定に直接適用できるか?
69例の後ろ向き研究で、結果は早期追跡に限られます。ROCの識別能力にも限界があり、提示されたカットオフを普遍的な手術目標とはできません。著者も、より大きなコホートと長期検証の必要性を指摘しています。
Keywords・キーワード
- intraoperative gap balance
- joint line preservation
- restricted kinematic alignment
- robotic-assisted surgery
- total knee arthroplasty
- TKA
- robotics
- joint line
Abstract・原文の抄録
Do Weon Lee, Du Hyun Ro, Hyuk-Soo Han. Limited Femoral Joint-Line Alteration and Preserved Extension Lateral Laxity Enhanced Early Outcomes in Restricted Kinematic Alignment Total Knee Arthroplasty. The Journal of arthroplasty. 2026:S0883-5403(26)00519-X. doi:10.1016/j.arth.2026.05.029.
BACKGROUND
Restricted kinematic alignment (rKA) total knee arthroplasty (TKA) seeks to restore native alignment while limiting excessive correction. The influence of alignment change magnitude and intraoperative gap characteristics on early patient-reported outcome measures (PROMs) after robotic rKA TKA remains unclear.
METHODS
This retrospective cohort study included 69 robotic-arm-assisted cruciate-retaining TKAs performed using an rKA protocol. Intraoperative medial and lateral extension and flexion gaps-extension medial gap, extension lateral gap, flexion medial gap (FMG), and flexion lateral gap-were recorded automatically. Preoperative and postoperative hip-knee-ankle (HKA) angle, lateral distal femoral angle (LDFA), and medial proximal tibial angle were measured using a validated deep learning model. Multivariable analyses of covariance evaluated associations between demographics, baseline alignment, alignment changes, gap characteristics, and PROMs at one and two years.
RESULTS
All PROMs improved postoperatively. Smaller changes in HKA and LDFA were independently associated with higher two-year Knee Society Knee Scores (P = 0.001 and P = 0.013). Greater ELG was associated with a higher two-year Forgotten Joint Score (P = 0.001), whereas greater FMG was associated with lower two-year Western Ontario and McMaster Universities Osteoarthritis Index pain and stiffness scores (P = 0.011 and P = 0.002). Receiver operating characteristic analyses identified changes in LDFA less than 2.3° (area under the curve [AUC] 0.622) and changes in HKA less than 8.4° (AUC 0.541) as thresholds associated with higher Knee Society Knee Score. An ELG ≥ 3.0 mm predicted higher Forgotten Joint Score (AUC 0.658), and FMG ≥ 1.5 mm predicted lower Western Ontario and McMaster Universities Osteoarthritis Index stiffness (AUC 0.716). No revisions occurred.
CONCLUSIONS
In robotic cruciate-retaining rKA TKA, minimizing femoral joint-line alteration and preserving controlled lateral extension laxity, along with mild medial flexion laxity, were associated with modestly improved early outcomes. These findings are exploratory and require validation in larger cohorts with longer follow-up.
オリジナル紙だ
Limited Femoral Joint-Line Alteration and Preserved Extension Lateral Laxity Enhanced Early Outcomes in Restricted Kinematic Alignment Total Knee Arthroplasty
Do Weon Lee, Du Hyun Ro, Hyuk-Soo Han
Journal of Arthroplasty · 2026