{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T08:28:03Z","timestamp":1787646483853,"version":"build-2736575974"},"reference-count":30,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T00:00:00Z","timestamp":1787616000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background\/Objectives: Accurate patient positioning is essential for diagnostic quality in conventional knee radiography. Although established anatomical landmarks are routinely used to judge projection quality, assessment remains qualitative and observer-dependent. We therefore developed and validated the Radiographic Projection Quality Score for the Knee (RPQS-Knee), a standardized scoring system for objective projection quality assessment. Methods: The RPQS-Knee was derived from established radiographic positioning criteria, anatomical reference landmarks, and predefined geometrically based measurement thresholds. The final score was evaluated in 153 consecutive knee radiographic examinations, independently assessed by one radiologist and two orthopedic surgeons. Inter rater reliability was assessed using quadratically weighted Gwet\u2019s AC2, intra rater reliability using weighted Cohen\u2019s \u03ba, and construct validity by correlation with separately assigned diagnostic adequacy ratings. Results: The RPQS-Knee comprises four projection-related criteria assessing fibular-head superimposition, tibial plateau alignment, and femoral-condyle congruency. Inter rater reliability was excellent for the total score (AC2 = 0.93; 95% CI, 0.92\u20130.95) and good to excellent for all individual items (AC2 = 0.76\u20130.85). Intra rater reliability ranged from \u03ba = 0.59 to 0.81. RPQS-Knee subscores correlated strongly with diagnostic adequacy ratings (\u03c1 = \u22120.69 and \u22120.78; both p &lt; 0.001), providing evidence supporting construct validity. Conclusions: The RPQS-Knee translates established radiographic positioning criteria into a standardized, reproducible instrument for objective assessment of projection quality. Its excellent reliability and evidence supporting construct validity suggest that it may facilitate standardized quality assessment in clinical practice, quality assurance, and research.<\/jats:p>","DOI":"10.3390\/diagnostics16172703","type":"journal-article","created":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T08:00:48Z","timestamp":1787644848000},"page":"2703","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Radiographic Projection Quality Score for the Knee (RPQS-Knee): Development and Reliability"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4747-8488","authenticated-orcid":false,"given":"Peter","family":"Melcher","sequence":"first","affiliation":[{"name":"Department of Orthopedics and Trauma Surgery, Helios Klinik Leisnig, 04703 Leisnig, Germany"},{"name":"Department for Orthopedics, Trauma and Plastic Surgery, University Hospital Leipzig, 04103 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5274-1896","authenticated-orcid":false,"given":"Ralf","family":"Henkelmann","sequence":"additional","affiliation":[{"name":"Department for Orthopedics, Trauma and Plastic Surgery, University Hospital Leipzig, 04103 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Salim","family":"Youssef","sequence":"additional","affiliation":[{"name":"Department for Orthopedics, Trauma and Plastic Surgery, University Hospital Leipzig, 04103 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anton","family":"Brehmer","sequence":"additional","affiliation":[{"name":"Department for Orthopedics, Trauma and Plastic Surgery, University Hospital Leipzig, 04103 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3313-3208","authenticated-orcid":false,"given":"Timm","family":"Denecke","sequence":"additional","affiliation":[{"name":"Department for Diagnostic and Interventional Radiology, University Hospital Leipzig, Liebigstra\u00dfe 20, 04103 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9456-3661","authenticated-orcid":false,"given":"Jeanette","family":"Henkelmann","sequence":"additional","affiliation":[{"name":"Department for Diagnostic and Interventional Radiology, University Hospital Leipzig, Liebigstra\u00dfe 20, 04103 Leipzig, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"555","DOI":"10.1007\/s00117-017-0242-y","article-title":"H\u00e4ufigkeit und Dosis diagnostischer und interventioneller R\u00f6ntgenanwendungen: Trends zwischen 2007 und 2014","volume":"57","author":"Nekolla","year":"2017","journal-title":"Radiologe"},{"key":"ref_2","unstructured":"United Nations Scientific Committee on the Effects of Atomic Radiation (2022). Sources, Effects and Risks of Ionizing Radiation, United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2020\/2021 Report, Volume I: Report to the General Assembly, with Scientific Annex A\u2014Evaluation of Medical Exposure to Ionizing Radiation, United Nations."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"S252","DOI":"10.1016\/j.jacr.2018.09.030","article-title":"ACR Appropriateness Criteria\u00ae Acutely Limping Child Up To Age 5","volume":"15","author":"Safdar","year":"2018","journal-title":"J. Am. Coll. Radiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"494","DOI":"10.1136\/ard.16.4.494","article-title":"Radiological assessment of osteo-arthrosis","volume":"16","author":"Kellgren","year":"1957","journal-title":"Ann. Rheum. Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"611","DOI":"10.1001\/jama.1996.03530320035031","article-title":"Prospective Validation of a Decision Rule for the Use of Radiography in Acute Knee Injuries","volume":"275","author":"Stiell","year":"1996","journal-title":"JAMA"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"731","DOI":"10.25122\/jml-2022-0341","article-title":"Assessment of image rejection in digital radiography","volume":"16","author":"Hasaneen","year":"2023","journal-title":"J. Med. Life"},{"key":"ref_7","unstructured":"Lampignano, J.P., and Kendrick, L.E. (2021). Bontrager\u2019s Handbook of Radiographic Positioning and Techniques, Mosby."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1016\/j.knee.2012.05.011","article-title":"The intra- and inter-rater reliability of X-ray radiological measurements for patellar instability","volume":"20","author":"Smith","year":"2013","journal-title":"Knee"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1002\/jmrs.796","article-title":"Multi-centre digital radiography reject analysis for different clinical room use types: The establishment of local reject reference levels for public hospital departments","volume":"71","author":"Serra","year":"2024","journal-title":"J. Med. Radiat. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1002\/jmrs.654","article-title":"Digital radiography reject analysis: A comparison between two radiology departments in New Zealand","volume":"70","author":"Bantas","year":"2023","journal-title":"J. Med. Radiat. Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1258\/ar.2011.110350","article-title":"Reject analysis in direct digital radiography","volume":"53","author":"Andersen","year":"2012","journal-title":"Acta Radiol."},{"key":"ref_12","unstructured":"Carmichael, J.H.E. (1996). European Guidelines on Quality Criteria for Diagnostic Radiographic Images\/[European Commission, Directorate-General XII: Science, Research and Development; Edited by J.H.E. Carmichael [and Others], Office for Official Publications of the European Communities."},{"key":"ref_13","first-page":"100022","article-title":"The need for a standardized whole leg radiograph guideline: The effects of knee flexion, leg rotation, and X-ray beam height","volume":"1","author":"Nguyen","year":"2021","journal-title":"J. Cartil. Jt. Preserv."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1007\/BF01552649","article-title":"Factors of patellar instability: An anatomic radiographic study","volume":"2","author":"Dejour","year":"1994","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1045","DOI":"10.1302\/0301-620X.92B8.23794","article-title":"The measurement of patellar height: A review of the methods of imaging","volume":"92","author":"Phillips","year":"2010","journal-title":"J. Bone Joint Surg. Br."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1141","DOI":"10.1007\/s00167-008-0620-0","article-title":"Lateral versus medial tibial plateau: Morphometric analysis and adaptability with current tibial component design","volume":"16","author":"Servien","year":"2008","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"581","DOI":"10.1186\/s13018-021-02740-8","article-title":"Radiographic optimization of the lateral position of the knee joint aided by CT images and the maximum intensity projection technique","volume":"16","author":"Wang","year":"2021","journal-title":"J. Orthop. Surg. Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"861","DOI":"10.3928\/0147-7447-19900801-09","article-title":"A mathematical analysis of the effect of flexion and rotation on apparent varus\/valgus alignment at the knee","volume":"13","author":"Krackow","year":"1990","journal-title":"Orthopedics"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1016\/j.knee.2023.02.012","article-title":"Quality of long standing radiographs assessment of the patella position","volume":"42","author":"Chen","year":"2023","journal-title":"Knee"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2982","DOI":"10.1007\/s00167-014-3327-4","article-title":"Predicting knee rotation by the projection overlap of the proximal fibula and tibia in long-leg radiographs","volume":"22","author":"Maderbacher","year":"2014","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"104357","DOI":"10.1016\/j.knee.2026.104357","article-title":"Relationship between tibio-fibular overlap ratio and lower limb torsion in an Asian population","volume":"60","author":"Tan","year":"2026","journal-title":"Knee"},{"key":"ref_22","first-page":"1","article-title":"Is there difference and correlation between medial and lateral tibial plateau coronal obliquity in native knee? A radiographic study","volume":"28","author":"Leung","year":"2021","journal-title":"J. Orthop. Trauma Rehabil."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1016\/j.knee.2007.05.004","article-title":"Morphometry of the proximal tibia to design the tibial component of total knee arthroplasty for the Korean population","volume":"14","author":"Kwak","year":"2007","journal-title":"Knee"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2563","DOI":"10.1016\/j.arth.2017.02.078","article-title":"Morphometry of the Tibial Plateau at the Surface and Resected Levels","volume":"32","author":"Zhang","year":"2017","journal-title":"J. Arthroplast."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"3048","DOI":"10.1007\/s00167-019-05777-9","article-title":"Anthropometry of the medial tibial plateau in the Chinese population: The morphometric analysis and adaptability with Oxford Phase III tibial components","volume":"28","author":"Lu","year":"2020","journal-title":"Knee Surg. Sports Traumatol. Arthrosc."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2325967116S00113","DOI":"10.1177\/2325967116S00113","article-title":"Predictors of Lateral Compartment Joint Space Difference at a Minimum of Two Years after ACL Reconstruction","volume":"4","author":"Jones","year":"2016","journal-title":"Orthop. J. Sports Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"581","DOI":"10.1016\/j.joca.2014.12.018","article-title":"Meniscus treatment and age associated with narrower radiographic joint space width 2\u20133 years after ACL reconstruction: Data from the MOON onsite cohort","volume":"23","author":"Jones","year":"2015","journal-title":"Osteoarthr. Cartil."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"675","DOI":"10.1177\/02841851251319666","article-title":"Some common statistical methods for assessing rater agreement in radiological studies","volume":"66","author":"Geijer","year":"2025","journal-title":"Acta Radiol."},{"key":"ref_29","unstructured":"Gwet, K.L. (2021). Analysis of Categorical Ratings, AgreeStat Analytics. [5th ed.]."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1177\/001316446002000104","article-title":"A Coefficient of Agreement for Nominal Scales","volume":"20","author":"Cohen","year":"1960","journal-title":"Educ. Psychol. Meas."}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/17\/2703\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T08:11:05Z","timestamp":1787645465000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/17\/2703"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,25]]},"references-count":30,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["diagnostics16172703"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics16172703","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,25]]}}}