Reverse Dorr Classification of Lateral Knee Radiographs: A Qualitative Assessment of Bone Quality in Total Knee Arthroplasty.
- 1Department of Orthopedics and Rehabilitation, University of Wisconsin, Madison, WI, USA.
- 2School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA.
Abstract
Background
The Dorr classification is the standard radiographic method for assessing proximal femur bone quality and guiding implant selection in total hip arthroplasty (THA); however, a similar method has not been established for total knee arthroplasty (TKA). Previous studies have demonstrated that radiographic parameters of the distal femur, specifically the ratio of the inner vs outer cortical diameter on lateral knee radiographs, are associated with bone mineral density. The aim of this study was to develop an efficient, reproducible, and qualitative classification system of the distal femur that correlates with bone mineral density to guide implant selection in TKA.Methods
A retrospective review of 200 TKA patients with preoperative dual-energy radiograph absorptiometry (DXA) within 1 year of TKA at a single institution was performed. Preoperative lateral knee radiographs were independently reviewed and the degree of anterior cortical taper of the distal femur between the trochlea and a point one patella height (Reverse Dorr 1 [RD1]) or two patella heights (RD2) proximal to the trochlea was graded as Reverse Dorr A, B, or C.Results
The Reverse Dorr classification system was associated with DXA T-score, intraoperative physician assessment, and demonstrated moderate to strong interobserver agreement. Reverse Dorr A femurs had a 59-70% predicted probability of normal bone, whereas Reverse Dorr C femurs had a 66-76% predicted probability of osteoporosis.Conclusions
The Reverse Dorr classification system is an efficient and reproducible assessment of preoperative bone quality and may serve to inform implant selection in TKA.
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BibTeX
@article{beilfuss2026reverse,
title = {{Reverse Dorr Classification of Lateral Knee Radiographs: A Qualitative Assessment of Bone Quality in Total Knee Arthroplasty.}},
author = {Matthew A Beilfuss and Micah MacAskill and Kyle R Wagner and Diane C Krueger and Sam Mosiman and Brian T Nickel},
journal = {Arthroplasty today},
year = {2026},
month = oct,
doi = {10.1016/j.artd.2026.102179},
url = {https://europepmc.org/article/MED/42903444},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Reverse Dorr Classification of Lateral Knee Radiographs: A Qualitative Assessment of Bone Quality in Total Knee Arthroplasty.
AU - Matthew A Beilfuss
AU - Micah MacAskill
AU - Kyle R Wagner
AU - Diane C Krueger
AU - Sam Mosiman
AU - Brian T Nickel
PY - 2026
DA - 2026/10/13
JO - Arthroplasty today
DO - 10.1016/j.artd.2026.102179
UR - https://europepmc.org/article/MED/42903444
AB - Background The Dorr classification is the standard radiographic method for assessing proximal femur bone quality and guiding implant selection in total hip arthroplasty (THA); however, a similar method has not been established for total knee arthroplasty (TKA). Previous studies have demonstrated that radiographic parameters of the distal femur, specifically the ratio of the inner vs outer cortical diameter on lateral knee radiographs, are associated with bone mineral density. The aim of this study was to develop an efficient, reproducible, and qualitative classification system of the distal femur that correlates with bone mineral density to guide implant selection in TKA.Methods A retrospective review of 200 TKA patients with preoperative dual-energy radiograph absorptiometry (DXA) within 1 year of TKA at a single institution was performed. Preoperative lateral knee radiographs were independently reviewed and the degree of anterior cortical taper of the distal femur between the trochlea and a point one patella height (Reverse Dorr 1 [RD1]) or two patella heights (RD2) proximal to the trochlea was graded as Reverse Dorr A, B, or C.Results The Reverse Dorr classification system was associated with DXA T-score, intraoperative physician assessment, and demonstrated moderate to strong interobserver agreement. Reverse Dorr A femurs had a 59-70% predicted probability of normal bone, whereas Reverse Dorr C femurs had a 66-76% predicted probability of osteoporosis.Conclusions The Reverse Dorr classification system is an efficient and reproducible assessment of preoperative bone quality and may serve to inform implant selection in TKA.
SN - 2352-3441
ER -