Evidence map›Paper›PMID 40340766›Full record

ArticleKnee surgery & related research2025

Does the coronal plane alignment of the ankle and subtalar joints normalize after total knee arthroplasty?

Katsuki Yamaguchi, Tatsuya Sakai, Masanori Fujii, Satoshi Takashima, Shuichi Eto, Yosuke Matsumura, Satomi Nagamine, Hirofumi Tanaka

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Article in Knee surgery & related research, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

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1 · What the graph read from it

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3 · Its place in the literature

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1 citing paper in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

8 authors.

Katsuki Yamaguchi *Department of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
Tatsuya Sakai *Department of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
Masanori FujiiDepartment of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan. masanorif9@gmail.com.ORCID http://orcid.org/0000-0002-0219-3147
Satoshi TakashimaDepartment of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
Shuichi EtoDepartment of Orthopaedic Surgery, National Hospital Organization Saga National Hospital, 1-20-1 Hinode, Saga, 849-0923, Japan.
Yosuke MatsumuraDepartment of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
Satomi NagamineDepartment of Orthopaedic Surgery, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
Hirofumi TanakaDepartment of Orthopaedic Surgery, Hyakutake Orthopaedics and Sports Clinic, 4-2-15 Mizugae, Saga, 840-0054, Japan.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundTotal knee arthroplasty (TKA) alters the lower extremity alignment, potentially affecting adjacent joints such as the ankle and subtalar joints. However, the relationship between changes in hindfoot alignment and ankle osteoarthritis (OA) after TKA remains incompletely understood. The purpose of this study was to clarify whether ankle and subtalar alignment normalizes after TKA and to identify factors associated with persistent malalignment.

methodsWe retrospectively analyzed 331 patients who underwent unilateral mechanical alignment (MA) TKA for knee osteoarthritis. A control group of 40 healthy subjects was used to define normal alignment ranges. Whole-leg anteroposterior weight-bearing radiographs were obtained preoperatively and 2 months postoperatively. Alignment parameters included the hip-knee-ankle angle (HKA), tibiotalar tilt angle (TTA), tibial plafond inclination angle (TPIA), talar inclination angle (TIA), and hindfoot alignment angle (HAA). Pre- and postoperative values were compared using the Wilcoxon signed-rank test, and changes in the proportion of patients within the normal range were determined. Wilcoxon rank-sum tests and chi-squared tests were used for group comparisons, and multivariate logistic regression identified independent predictors of persistent malalignment.

resultsHKA improved after TKA (-12° to -2.0°), with corresponding improvements in TPIA (99° to 94°) and TIA (99° to 95°) (all p < 0.001), indicating a significant correction toward neutral alignment. The proportion of patients within normal range increased postoperatively from 16% to 85% for HKA, 26% to 67% for TPIA, 24% to 64% for TIA, and 65% to 73% for HAA. Multivariate analysis identified ankle OA (odds ratio [OR] = 6.62 for TTA), female sex (OR = 2.32 for TPIA; OR = 3.19 for TIA), and varus knee alignment (OR = 2.81 for TIA) as independent predictors of persistent malalignment.

conclusionsMA-TKA facilitates partial normalization of coronal hindfoot alignment, particularly at the tibial plafond and talus. However, female sex, varus knee deformity, and pre-existing ankle OA independently limit full correction. These findings highlight the biomechanical interdependence between the knee and hindfoot and may guide surgical decision-making and patient-specific alignment strategies.

Indexed as

Ankle osteoarthritisCoronal alignmentHindfoot alignmentSubtalar jointTotal knee arthroplasty

Identifiers

PMID40340766
PMCPMC12063276

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