Long leg radiographs underestimate the degree of constitutional varus limb alignment and joint line obliquity in comparison with computed tomography: a radiographic study
Abstract
Purpose The purpose of this study was to understand if differences exist between computed tomography (CT) and long leg radiographs (LLR) when defining coronal plane alignment of the lower limb in total knee arthroplasty (TKA). It aimed to identify any such differences between the two imaging modalities by quantifying constitutional limb alignment (arithmetic hip-knee-ankle angle (aHKA), joint line obliquity (JLO) and Coronal Plane Alignment of the Knee (CPAK) type within the same population. Methods A retrospective radiographic study compared pre-operative LLR and CT measurements in patients undergoing robotic-assisted TKA. The aHKA, JLO and CPAK types were calculated after measuring the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). The primary outcomes were the mean differences in aHKA (MPTA-LDFA), JLO (MPTA + LDFA) and proportions of CPAK types between LLR and CT groups. The secondary outcomes were the differences in CT-derived MPTA values based on four different tibial sagittal landmarks. Results After exclusions, 465 imaging sets were analysed in 394 patients. There was a statistically significant mean difference between LLR and CT, respectively, for both MPTA (87.5° vs. 86.2°; p Conclusion Alignment determined by LLRs underestimates the magnitude of both constitutional varus alignment and joint line obliquity compared to CT, differences that notably increase the proportions of patients included in CPAK Types I and II. These distinctions are…
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Our data are consistent with the observation that MPTA is sensitive to the sagittal position of tibial landmarks, reflected by increased standard deviations for MPTA compared to LDFA for both literature-based (2.6° vs 1.7°) and optimized (2.5° vs 1.6°) cartilage assumptions.
“Our data are consistent with this observation, which is reflected by increased standard deviations for the MPTA compared to the LDFA for both the literature-based cartilage-assumptions (2.6° vs. 1.7°) and the optimized cartilage-assumptions (2.5° vs. 1.6°).”
From Imageless robotic total knee arthroplasty determines similar coronal plane alignment of the knee (CPAK) parameters to long leg radiographs (2024) · cites this paper as [17]
Tarassoli et al. reported that long leg radiographs underestimated proximal tibial varus in comparison to CT-based assessments by 1.3° on average.
“Tarassoli et al. reported, in a subsequent study, that long leg radiographs underestimated proximal tibial varus in comparison to CT-based assessments by 1.3° on average [17].”
From Imageless robotic total knee arthroplasty determines similar coronal plane alignment of the knee (CPAK) parameters to long leg radiographs (2024) · cites this paper as [17]
Some methods based on CT or MRI use proprietary algorithms that may not be accessible to all surgeons.
“Some of the methods based on CT or MRI use proprietary algorithms that may not be accessible to all surgeons [14–17].”
From Imageless robotic total knee arthroplasty determines similar coronal plane alignment of the knee (CPAK) parameters to long leg radiographs (2024) · cites this paper as [17]
The ability of CT-based robotics to define constitutional alignment and CPAK has been established.
“The ability of CT-based robotics to define constitutional alignment and CPAK has been established [16–18], yet it remains unknown if imageless intraoperative robotic data can accurately describe CPAK parameters [19–23].”
From Imageless robotic total knee arthroplasty determines similar coronal plane alignment of the knee (CPAK) parameters to long leg radiographs (2024) · cites this paper as [17]
Cited by
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Edelstein, A. I., Orsi, A. D., Plaskos, C., Coffey, S., & Suleiman, L. I. (2024) · Arthroplasty · doi:10.1186/s42836-024-00231-9 · Cited by 11 · see citing works
“Some of the methods based on CT or MRI use proprietary algorithms that may not be accessible to all surgeons [14–17].”
BackgroundMethodResultInfluential
- Authors
- Tarassoli, P., Corban, L. E., Wood, J. A., Sergis, A., Chen, D. B., & MacDessi, S. J.
- Affiliations
- <!--<label>1</label>--> Sydney Knee Specialists Suite 201, Level 2, 131 Princes Hwy 2217 Kogarah NSW Australia
- <!--<label>3</label>--> Stryker Australia 8 Herbert St 2065 St Leonards NSW Australia
- St George Hospital (AU)
- UNSW Sydney (AU)
- Corresponding author
- MacDessi, Samuel J.
- Venue
- Knee Surgery, Sports Traumatology, Arthroscopy
- Publisher
- Wiley
- Published
- 2023-07-25
- Volume
- 31
- Issue
- 11
- Pages
- 4755-4765
- ISSN
- 0942-2056 (ISSN-L)
- 1433-7347
- OpenAlex
- W4385230456
- Cited by
- 51
- References
- 0
- Citations by year
- 2026: 9 · 2025: 26 · 2024: 16
- FWCI
- 13.62
- Type
- journal article
- Language
- en
- Open access
- closed
- Licence
- Locations
- Knee Surgery Sports Traumatology Arthroscopy (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Surgery › Total Knee Arthroplasty Outcomes
- Health Sciences › Medicine › Surgery › Knee injuries and reconstruction techniques
- Physical Sciences › Engineering › Biomedical Engineering › Lower Extremity Biomechanics and Pathologies
- Keywords
- total knee arthroplasty, long-leg radiographs, computed tomography, limb alignment, joint line obliquity, coronal plane alignment of the knee, medial proximal tibial angle, lateral distal femoral angle, robotic surgery, preoperative imaging, tibial varus
- MeSH terms
- Aged, Aged, 80 and over, Female, Humans, Knee Joint, Male, Middle Aged, Radiography, Retrospective Studies, Tibia, Tomography, X-Ray Computed, Bone Malalignment, Arthroplasty, Replacement, Knee, Osteoarthritis, Knee
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