Evaluation of finger A3 pulley rupture in the crimp grip position-a magnetic resonance imaging cadaver study.
OBJECTIVE
The correct diagnosis of an A3 pulley rupture is challenging for musculoskeletal radiologists. An A3 pulley rupture should in theory influence the shape of the proximal interphalangeal joint volar plate (VP) and the amount of bowstringing at level of the VP during finger flexion. The purpose of this study was to perform MRI with metric analysis of the VP configuration and VP bowstringing in cadaver fingers in the crimp grip position and to determine cut points for A3 pulley rupture.


METHODS
MRI in the crimp grip position was performed in 21 cadaver fingers with artificially created flexor tendon pulley tears (fingers with A3 pulley rupture n = 16, fingers without A3 pulley rupture n = 5). The distances of the translation of the VP relative to the middle phalanx base, the distances between the flexor tendons and the VP body, and the distances between the flexor tendon and bone (TB) were measured.


RESULTS
Statistical analysis showed significantly lower VP translation distances and significantly higher VP tendon distances if the A3 pulley was ruptured. A2 TB and A4 TB distances did not differ significantly in specimens with and without A3 pulley rupture. The optimal cut points for A3 pulley rupture were a VP translation distance <2.8 mm and a VP tendon distance >1.4 mm.


CONCLUSIONS
Reduction of the VP translation distance and augmentation of the VP tendon distance are suitable indirect signs of A3 pulley rupture.
Department of Radiology, University of Erlangen-Nuremberg, Maximiliansplatz 1, 91054, Erlangen, Germany, thomas.bayer@uk-erlangen.de.
Thomas
T
Bayer
Werner
W
Adler
Andreas
A
Schweizer
Isabelle
I
Schöffl
Michael
M
Uder
Rolf
R
Janka
D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005383:Finger Injuries / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D056888:Patient Positioning / Q000379:methods*; D011187:Posture; D015203:Reproducibility of Results; D012422:Rupture, Spontaneous / Q000473:pathology; D012680:Sensitivity and Specificity; D013708:Tendon Injuries / Q000473:pathology*; D013710:Tendons / Q000473:pathology*