Khalifa AA, Lemma S, Fadle AA. In knee osteoarthritis, what is the knee deformity threshold after which the ankle realigns beyond the neutral zone? World J Orthop 2026; 17(5): 118547 [DOI: 10.5312/wjo.v17.i5.118547]
Corresponding Author of This Article
Ahmed A Khalifa, MD, Assistant Professor, FRCS, Department of Orthopaedics, Qena Faculty of Medicine and University Hospital, South Valley University, Kilo 6 Qena-Safaga Highway, Qena 83523, Egypt. ahmed_adel0391@med.svu.edu.eg
Research Domain of This Article
Orthopedics
Article-Type of This Article
Observational Study
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Khalifa AA, Lemma S, Fadle AA. In knee osteoarthritis, what is the knee deformity threshold after which the ankle realigns beyond the neutral zone? World J Orthop 2026; 17(5): 118547 [DOI: 10.5312/wjo.v17.i5.118547]
World J Orthop. May 18, 2026; 17(5): 118547 Published online May 18, 2026. doi: 10.5312/wjo.v17.i5.118547
In knee osteoarthritis, what is the knee deformity threshold after which the ankle realigns beyond the neutral zone?
Ahmed A Khalifa, Shikuria Lemma, Amr A Fadle
Ahmed A Khalifa, Department of Orthopaedics, Qena Faculty of Medicine and University Hospital, South Valley University, Qena 83523, Egypt
Ahmed A Khalifa, Department of Orthopedics, Aster Sanad Hospital, Riyadh 14236, Riyadh, Saudi Arabia
Shikuria Lemma, Department of Orthopaedics, Black Lion Specialized Hospital, Addis Ababa 1165, Ethiopia
Amr A Fadle, Department of Orthopedic Surgery and Traumatology, Assiut University Hospital, Assiut 71515, Egypt
Author contributions: Khalifa AA conceived and designed the study, carried out a statistical analysis, and did the critical revision; Lemma S and Fadle AA performed data acquisition, assessment, and literature searches, and prepared the images and tables; Fadle AA performed the measurements; Khalifa AA and Lemma S drafted the manuscript; all authors read, discussed, and approved the final manuscript.
Institutional review board statement: This article does not contain any experimental studies with human participants or animals performed by any of the authors, and it was approved by Assiut Faculty of Medicine Institutional Review Board (Approval No. 4-2024-300470).
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: The authors declare no conflict of interest.
STROBE statement: The authors have read the STROBE Statement—checklist of items, and the manuscript was prepared and revised according to the STROBE Statement—checklist of items.
Corresponding author: Ahmed A Khalifa, MD, Assistant Professor, FRCS, Department of Orthopaedics, Qena Faculty of Medicine and University Hospital, South Valley University, Kilo 6 Qena-Safaga Highway, Qena 83523, Egypt. ahmed_adel0391@med.svu.edu.eg
Received: January 5, 2026 Revised: January 29, 2026 Accepted: February 27, 2026 Published online: May 18, 2026 Processing time: 133 Days and 13.7 Hours
Core Tip
Core Tip: We investigated 845 lower limbs with primary knee osteoarthritis (OA) and detected an association between knee deformity and ankle joint alignment in the coronal plane. Varus knee alignment was the most commonly occurring and was strongly associated with varus ankle alignment, whereas valgus knees showed heterogeneous ankle adaptation. The hip to knee to ankle angle (HKAA) and the tibiotalar angle were moderately correlated, with knee alignment as the significant determinant of ankle alignment, independent of age and sex. OA severity (Kellgren-Lawrence grades) was associated with progressively greater varus alignment at the knee and ankle. The ankle joint will align beyond the accepted neutral range at specific HKAA thresholds of approximately 175.7° and 189.2° for varus and valgus knee deformity, respectively. These thresholds were consistent across sex and OA severity, underscoring the primacy of coronal knee alignment in driving ankle compensation.
