Introduction of an alternative standardized radiographic measurement method to evaluate volar angulation in subcapital fractures of the 5th metacarpal.
OBJECTIVE
The purpose of the present study was to compare the intra- and interobserver reliability of two different measurement methods for volar angulation of the 5th metacarpal (MC) in an attempt to establish a new standard measurement method to reduce interobserver discrepancies for therapeutic decisions.


METHODS
Twenty patients with subcapital fractures of the 5th MC were radiologically investigated. Imaging consisted of a radiographs in antero-posterior and precise lateral view in addition to a CT scan of the 5th MC. Measurement of volar angulation was accomplished using the conventional and the shaft articular surface (SAS) method. The measurements of five investigators were exported to a spreadsheet for statistical analysis to evaluate the intra-and interobserver reliability.


RESULTS
The conventional technique showed large differences among the investigators and poor interobserver reliability (W = 0.328 and 0.307) both at injury (p = 0.001) and at follow-up (p = 0.189). The intraobserver concordance of all investigators showed better results with the SAS than with the conventional technique. With the SAS technique, no statistically significant difference among the investigators could be detected at either the time of injury (p = 0.418) or at follow-up (p = 0.526) with excellent interobserver reliability (W = 0.051 and W = 0.041). Evaluation of volar angulation at follow-up using CT scans did not show any statistically significant difference between the techniques with better correlation among the observers with the SAS technique (p = 0.838).


CONCLUSIONS
The interobserver correlation of volar angulation with lateral radiographs using the conventional technique was insufficient. Therefore, we recommend the use of the novel SAS technique as standardized measurement method which showed higher accuracy and interobserver reliability in order to facilitate the choice of adequate treatment option.


CONCLUSIONS
A CT scan should be performed in cases with ambivalent treatment options.


METHODS
Evidence-Based Medicine Level II.
Department of Traumatology and Sports Injuries, University of Salzburg, Salzburg, 5020, Muellner Hauptstrasse 48, Austria. t.hoffelner@salk.at
Thomas
T
Hoffelner
Herbert
H
Resch
Philipp
P
Moroder
Gundobert
G
Korn
Felix
F
Steinhauer
Jörg
J
Atzwanger
Bernd
B
Minnich
Mark
M
Tauber
D000328:Adult; D001317:Austria; D051224:Capitate Bone / Q000000981:diagnostic imaging* / Q000293:injuries*; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D050279:Metacarpal Bones / Q000000981:diagnostic imaging* / Q000293:injuries*; D053401:Palmar Plate / Q000528:radiation effects*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000592:standards*