Comparison of coronal alignment measured on postoperative short-leg and standing long-leg radiographs following total knee arthroplasty.
4 affiliations
- 1Steve Biko Academic Hospital, Pretoria, South Africa.
- 2Dr. George Mukhari Academic Hospital, Ga-Rankuwa, South Africa.
- 3University of Pretoria, South Africa.
- 4Steve Biko Academic Hospital and Life Faerie Glen Hospital, Pretoria, South Africa.
Abstract
Introduction
Coronal alignment following total knee arthroplasty (TKA) is commonly assessed using radiographs, but postoperative radiographic protocols are not standardised. This study evaluated agreement between coronal alignment measured on short-leg and standing long-leg radiographs. We hypothesised that, in knees demonstrating varus alignment on standing long-leg radiographs, short-leg radiographs would demonstrate greater apparent varus.Methods
This retrospective cross-sectional study included 62 sequentially selected patients following primary TKA. All included patients had both postoperative short-leg and standing long-leg radiographic examinations available for analysis. Coronal alignment was assessed using the β angle. Agreement was evaluated using paired differences and Bland-Altman analysis. Interobserver reliability was assessed across six observers (two primary observers and four additional colleagues) using ICC(2,6). Intraobserver reliability was assessed using ICC(3,1).Results
The mean paired difference (short-leg minus standing long-leg) was -1.13° (95% confidence interval [CI]: -1.40° to -0.85°), indicating a systematic shift towards a more varus measurement on short-leg radiographs. The 95% limits of agreement were -4.08° to -1.82°, and 29% of measurements differed by more than 2°. In the 47 varus knees, the mean difference was -0.79° (95% CI: -1.18° to -0.40°; p < 0.001). In the valgus subgroup (n = 14; one neutral knee excluded), the mean difference was -2.31° (95% CI: -3.22° to -1.40°; p < 0.001).Discussion
Short-leg and standing long-leg radiographs demonstrate systematic differences in postoperative coronal-alignment measurement. Although the overall mean difference was modest, the relatively wide limits of agreement indicate that larger discrepancies can occur in individual patients. Short-leg radiographs should not be considered interchangeable with standing long-leg radiographs when accurate assessment of the lower-limb mechanical axis is required.
Related
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- Single-leg versus double-leg weight-bearing radiographs for coronal alignment assessment in patients with lower extremity trauma
- Reverse Dorr Classification of Lateral Knee Radiographs: A Qualitative Assessment of Bone Quality in Total Knee Arthroplasty.
- Kinematic Alignment in Total Knee Arthroplasty: Unresolved Challenges and Barriers to Overcome for Universal Application
BibTeX
@article{schanknecht2026comparison,
title = {{Comparison of coronal alignment measured on postoperative short-leg and standing long-leg radiographs following total knee arthroplasty.}},
author = {Rory Schanknecht and Carel Willemse and Bakatuasa Freddy Mulunda and Adriaan de Villiers and Gopika Ramkilawon and Hans Jacobs},
journal = {SICOT-J},
year = {2026},
month = oct,
doi = {10.1051/sicotj/2026079},
url = {https://europepmc.org/article/MED/42932858},
note = {CC BY},
}
RIS
TY - JOUR
TI - Comparison of coronal alignment measured on postoperative short-leg and standing long-leg radiographs following total knee arthroplasty.
AU - Rory Schanknecht
AU - Carel Willemse
AU - Bakatuasa Freddy Mulunda
AU - Adriaan de Villiers
AU - Gopika Ramkilawon
AU - Hans Jacobs
PY - 2026
DA - 2026/10/26
JO - SICOT-J
DO - 10.1051/sicotj/2026079
UR - https://europepmc.org/article/MED/42932858
AB - Introduction Coronal alignment following total knee arthroplasty (TKA) is commonly assessed using radiographs, but postoperative radiographic protocols are not standardised. This study evaluated agreement between coronal alignment measured on short-leg and standing long-leg radiographs. We hypothesised that, in knees demonstrating varus alignment on standing long-leg radiographs, short-leg radiographs would demonstrate greater apparent varus.Methods This retrospective cross-sectional study included 62 sequentially selected patients following primary TKA. All included patients had both postoperative short-leg and standing long-leg radiographic examinations available for analysis. Coronal alignment was assessed using the β angle. Agreement was evaluated using paired differences and Bland-Altman analysis. Interobserver reliability was assessed across six observers (two primary observers and four additional colleagues) using ICC(2,6). Intraobserver reliability was assessed using ICC(3,1).Results The mean paired difference (short-leg minus standing long-leg) was -1.13° (95% confidence interval [CI]: -1.40° to -0.85°), indicating a systematic shift towards a more varus measurement on short-leg radiographs. The 95% limits of agreement were -4.08° to -1.82°, and 29% of measurements differed by more than 2°. In the 47 varus knees, the mean difference was -0.79° (95% CI: -1.18° to -0.40°; p < 0.001). In the valgus subgroup (n = 14; one neutral knee excluded), the mean difference was -2.31° (95% CI: -3.22° to -1.40°; p < 0.001).Discussion Short-leg and standing long-leg radiographs demonstrate systematic differences in postoperative coronal-alignment measurement. Although the overall mean difference was modest, the relatively wide limits of agreement indicate that larger discrepancies can occur in individual patients. Short-leg radiographs should not be considered interchangeable with standing long-leg radiographs when accurate assessment of the lower-limb mechanical axis is required.
SN - 2426-8887
ER -