Comparison of coronal alignment measured on postoperative short-leg and standing long-leg radiographs following total knee arthroplasty.

Authors

Rory Schanknecht, Carel Willemse, Bakatuasa Freddy Mulunda, Adriaan de Villiers, Gopika Ramkilawon, Hans Jacobs

Published in

SICOT-J. Volume 12. Pages 76. Epub Oct 26, 2026.

Abstract

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.
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).
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).
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.

PMID:
42932858
Bibliographic data and abstract were imported from PubMed on 27 Oct 2026.

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