ArticleArchives of orthopaedic and trauma surgery2025
The CPAK classification in three-dimensional measurements is consistent with those in two-dimensional measurements.
Article in Archives of orthopaedic and trauma surgery, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 6 papers, 1 of them a synthesis that pooled it.
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Who cites it
6 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Discrepancies in CPAK classification between CT and long-leg radiography: a systematic review and meta-analysis.Skeletal radiology · 2026Pooled it
- Distribution of coronal plane alignment knee phenotypes in Japanese patients with knee osteoarthritis: a comparison of two-dimensional and three-dimensional measurements.Journal of orthopaedics · 2026Article
- Radiolucent lines after robotic-assisted surface-matching kinematically aligned UKA: short-term incidence and lack of association with tibial alignment.Archives of orthopaedic and trauma surgery · 2026Article
- The coronal plane alignment of the knee classification cannot ignore the joint line convergence angle.BMC musculoskeletal disorders · 2026Article
- Computed tomography versus long-leg radiography for CPAK-based coronal alignment assessment in total knee arthroplasty: a prospective evaluation.Journal of robotic surgery · 2025Article
- Femoral component rotational alignment in robotic-assisted total knee arthroplasty with functional knee positioning varies across knee phenotypes without affecting clinical outcomes.Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA · 2025Observational
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Authors and funding
6 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeThis study aimed to evaluate whether the coronal plane alignment of the knee (CPAK) classification between three-dimensional (3D) measurement using computed tomography (CT) and two-dimensional (2D) measurement using long leg radiographs (LLR) match.
methodsA retrospective radiographic study compared pre-operative CT and LLR measurements in 69 patients undergoing primary total knee arthroplasty. The arithmetic hip-knee-ankle angle (aHKA), joint line obliquity (JLO), and CPAK types were calculated. A match in the CPAK classification was defined as "complete agreement" and agreement was considered partial if the CPAK was located in an adjacent column. If the discrepancy was more than one column, then it was recorded as no agreement.
resultsThe mean aHKA was - 0.6° ± 4.4° in 3D measurement and - 1.1° ± 4.3° in 2D measurement (p = 0.42). The mean JLO was 174.2° ± 3.5° in 3D measurement and 175.2° ± 3.6° in 2D measurement (p = 0.07). There was no statistically significant difference in either aHKA or JLO obtained by the two measurement methods, each within 1°. However, the complete agreement was confirmed in only 60.8% of cases. After incorporating even partial agreements including neighboring columns, the agreement rate was 91.2%. The disagreement was noticed in 8.8% of the cases.
conclusionThe 3D measurement method enables aHKA and JLO calculations similar to those of 2D measurements. However, complete agreement with the CPAK classification in all cases was not obtained. On the other hand, 2D measurement has the advantage that JLO can be easily appreciated and remais more intuitive for surgeons. LEVEL OF EVIDENCE: III.
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