University of Oulu

Nevalainen, M.T., Roedl, J.B., Morrison, W.B. et al. Skeletal Radiol (2019) 48: 1079.

MRI of a painful carpal boss : variations at the extensor carpi radialis brevis insertion and imaging findings in regional traumatic and overuse injuries

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Author: Nevalainen, Mika T.1,2,3,4; Roedl, Johannes B.1; Morrison, William B.1;
Organizations: 1Division of Musculoskeletal Imaging and Intervention, Department of Radiology, Thomas Jefferson University Hospitals, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, USA
2Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
3Medical Research Center Oulu, University of Oulu, Oulu, Finland
4Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.5 MB)
Persistent link:
Language: English
Published: Springer Nature, 2019
Publish Date: 2019-06-07


Objective: To report patterns of MRI findings involving carpal boss and extensor carpi radialis brevis (ECRB) tendon insertion in individuals with overuse-related or post-traumatic wrist pain.

Materials and Methods: Eighty-four MRI cases with carpal bossing between December 2006 and June 2015 were analyzed by two fellowship-trained musculoskeletal radiologists. The following MRI findings were reviewed: type of carpal bossing (bony prominence, partial coalition, os styloideum), insertion of ECRB tendon (to the 3rd metacarpal, to carpal boss or to both), bone marrow edema (BME), insertion site, and tenosynovitis/tendinosis of ECRB tendon. Clinical information on wrist pain was available on 68 patients.

Results: Fused carpal bossing was detected in 21%, partial coalition in 35%, and os styloideum in 44% of the cases. Regional BME was observed in 64% of the cases. When BME specifically at the carpal boss was assessed, 78% of stable and 50% of unstable bosses showed BME (p = 0.035). ECRB tendon inserted on a carpal boss in 20%, on the 3rd metacarpal bone in 35%, and on both sites in 45% of the cases. As BME at the carpal boss was assessed, BME was detected at the respective insertion sites in 71%, 35%, and 66% of the cases (p = 0.015). Dorsal wrist pain was associated with BME as 75% of the patients had regional BME in the vicinity of the carpal boss (p = 0.006).

Conclusion: A spectrum ranging from complete fusion of a boss to an entirely unfused os styloideum exists with a variable ECRB insertional anatomy. BME at the carpal boss is a consistent MRI finding.

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Series: Skeletal radiology
ISSN: 0364-2348
ISSN-E: 1432-2161
ISSN-L: 0364-2348
Volume: 48
Issue: 7
Pages: 1079 - 1085
DOI: 10.1007/s00256-018-3136-9
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Funding: Open access funding provided by University of Oulu including Oulu University Hospital.
Copyright information: © The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.