scapula fracture classification system - Kreiskrankenhaus Mechernich

516 M. Jaeger et al.
Figure 5
Focused classification system of multifragmentary joint fractures (F2). Ó 2012, Jaeger et al.
Figure 6
Example of a 3D CT reconstruction video used for the last classification session. Ó 2012, Jaeger et al.
format, anonymized, and distributed on DVD format to SCCG
members, who classified fractures independently ‘‘at home’’
within a 3-month period. Fracture codes were collected electronically
using specifically designed Excel sheets (Microsoft, Redmond,
WA, USA), which were centralized for the analyses. The
results including reliability and accuracy data were reviewed
during face-to-face meetings to identify the reasons for coding
disagreements and improving the system.
The final session included 120 cases documented with the
2-dimensional CT series and 3D CT reconstruction videos, as well
as additional radiographs available from 105 cases. Data were
managed and analyzed by use of Intercooled Stata, version 11
(StataCorp LP, College Station, TX, USA). The basic system was
first analyzed to assess the likely distribution of articular segment
(F0/F1/F2) fractures in the sample and identify them. The focused
system was then applied to this fracture subset and separately
analyzed for simple fracture patterns (F1) and multifragmentary
joint fractures (F2). Interobserver reliability was evaluated by
means of k coefficients. The k coefficient is commonly used as
a chance-corrected measure of agreement, which ranges from þ1
(complete agreement) to 0 (agreement by chance alone) to less
than 0 (less agreement than expected by chance). The k coefficient
is a useful indicator of reliability, and a value of 0.70 is considered
an adequate sign of reliability. Classification accuracy was estimated
by latent class modeling 22,23 using Latent GOLD software,
version 3.0.1 (Statistical Innovations, Belmont, MA, USA). This
technique aims at identifying the most likely ‘‘true’’ distribution of
fracture classes in the population of scapula fractures based on the
evaluated sample and the agreement data collected among the
participating surgeons; for each class, the degree of classification
accuracy for each surgeon is also estimated. 6
Results
When identifying cases using the basic system to classify
a fracture of the articular segment (denoted F), the
7 shoulder specialists were in agreement for 73% of the 120