Comparison of coronal alignment measured on postoperative short-leg and standing long-leg radiographs following total knee arthroplasty
Year: 2026
Type: article
Study design: Observational Study
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.
Source: SICOT-J
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $1,641
OpenAlex ID: W7223666560