Purpose
The objectives of this study were to (1) evaluate the radiographic characteristics
of children with congenital thumb duplication (CTD) seen in our institution between
August 2015 and April 2021; (2) introduce a modified radiographic classification system
(MCS) capable of including all cases of CTD based on their radiographic pathoanatomy;
and (3) evaluate the inter- and intrarater reliability of the new classification system.
Methods
We retrospectively reviewed 2,108 patients with 2,300 CTDs. The MCS is based on the
Wassel-Flatt and Chung et al classification systems and includes specific subtypes
from the Rotterdam and modified Wassel-Flatt classifications. The MCS is characterized
by 4 groups according to the anatomical morphology of the duplication: A (joint),
B (epiphysis), C (bone), and D (soft tissues). Each group includes 4 subtypes according
to the location of the CTD, with subtypes 1–3 extending from the distal phalanx to
the metacarpal or interphalangeal joints, then to the carpometacarpal joint, and with
subtype 4 only including the triphalangia of the main thumb.
Results
Among the 2,300 fingers, 360 (15.7%), 2 (0.1%), and 3 (0.1%) CTDs could not be classified
according to the Wassel-Flatt, Chung et al, and Rotterdam classifications, respectively.
According to the MCS, the 2 most common forms of CTD were A2 (680/2,300; 29.6%) and
D2 (308/2,300; 13.4%). All cases could be classified according to this classification
system. The MCS showed excellent intrarater (0.875) and interrater (0.851) reliability
relative to the Wassel-Flatt (0.863 and 0.820, respectively), Chung et al (0.793 and
0.822, respectively), and Rotterdam (0.873 and 0.836, respectively) systems.
Conclusions
The MCS is a potential radiographic classification for CTD that enables the classification
of all patients and has excellent inter- and intrarater reliability.
Clinical relevance
Existing classification systems do not allow classification of the full spectrum of
CTD and are not always related to surgery, and some existing systems are complex,
with many categories that are rarely encountered, or are difficult to use widely in
clinical practice.
Key words
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Article info
Publication history
Published online: August 05, 2022
Accepted:
June 1,
2022
Received:
November 14,
2021
Publication stage
In Press Corrected ProofFootnotes
J.W., W.S., and X.L. contributed equally to this manuscript.
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
Identification
Copyright
© 2022 by the American Society for Surgery of the Hand. All rights reserved.
