ArticleActa orthopaedica2014
Where is the neck? Alpha angle measurement revisited.
Article in Acta orthopaedica, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 13 papers.
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Who cites it
13 citing papers in PubMed, 25 citations in OpenAlex.
- Proximal Femoral Morphology in Development Dysplasia of the Hip Based on Three-Dimensional (3D) Analysis.Malaysian orthopaedic journal · 2025Article
- Capsular attachment on the anterosuperior femoral head-neck junction: A hypothesis about femoroacetabular impingement.Journal of anatomy · 2024Article
- Limited angular remodelling after in-situ fixation for slipped capital femoral epiphysis : A study on radiographs from the Swedish pediatric orthopaedic quality registry for SCFE.BMC musculoskeletal disorders · 2024Article
- Is a Femoro-Acetabular Impingement Type Cam Predictable after Slipped Capital Femoral Epiphysis?Children (Basel, Switzerland) · 2021Article
- Measuring 3D growth plate shape: Methodology and application to cam morphology.Journal of orthopaedic research : official publication of the Orthopaedic Research Society · 2021Article
- Classifying Cam Morphology by the Alpha Angle: A Systematic Review on Threshold Values.Orthopaedic journal of sports medicine · 2020Review
- Correlations and Reproducibility Between Radiographic and Radial Alpha Angles in the Evaluation of Cam Morphology.Orthopaedic journal of sports medicine · 2020Article
- Femoroacetabular impingement: question-driven review of hip joint pathophysiology from asymptomatic skeletal deformity to end-stage osteoarthritis.Journal of orthopaedics and traumatology : official journal of the Italian Society of Orthopaedics and Traumatology · 2019Review
- Validity of the alpha angle measurements on plain radiographs in the evaluation of cam-type femoroacetabular impingement in patients with slipped capital femoral epiphysis.Skeletal radiology · 2019Article
- Using a numerical method to precisely evaluate the alpha angle in a hip image.Medical & biological engineering & computing · 2019Article
- Visualization of a cam-type femoroacetabular impingement while squatting using image-matching techniques: a case report.Skeletal radiology · 2017Article
- Which anatomical conditions are associated with limitations of the hip function after SCFE?Journal of orthopaedicsArticle
- Anatomic Study of Hip Pericapsular Muscle Arrangement on the Joint Capsule.JB & JS open accessArticle
Corrections and comments
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Authors and funding
6 authors at 3 institutions in 3 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
background and purposeThe alpha angle is the most used measurement to classify concavity of the femoral head-neck junction. It is not only used for treatment decisions for hip impingement, but also in cohort studies relating hip morphology and osteoarthritis. Alpha angle measurement requires identification of the femoral neck axis, the definition of which may vary between studies. The original "3-point method" uses 1 single point to construct the femoral neck axis, whereas the "anatomic method" uses multiple points and attempts to define the true anatomic neck axis. Depending on the method used, the alpha angle may or may not account for other morphological characteristics such as head-neck offset.
methodsWe compared 2 methods of alpha angle measurement (termed "anatomic" and "3-point") in 59 cadaver femora and 83 cross-table lateral radiographs of asymptomatic subjects. Results were compared using Bland-Altman plots.
resultsDiscrepancies of up to 13 degrees were seen between the methods. The 3-point method had an "equalizing effect" by disregarding femoral head position relative to the neck: in femora with high alpha angle, it resulted in lower values than anatomic measurement, and vice versa in femora with low alpha angles. Using the anatomic method, we derived a reference interval for the alpha angle in normal hips in the general population of 30-66 degrees.
interpretationWe recommend the anatomic method because it also reflects the position of the femoral head on the neck. Consensus and standardization of technique of alpha angle measurement is warranted, not only for planar measurements but also for CT or MRI-based measurements.
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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.