Surgeon Interpretations of CT Scans of Scaphoid Waist Fractures Vary Widely
Key findings
- 140 surgeons were asked to rate the percentage and location of bony bridging on CT scans of scaphoid waist fractures
- Interobserver agreement about the degree of partial union was only fair
- Agreement about the location of bony bridging was also only fair
- Observers rated the confidence in their responses as 3.8 on a scale of 0 (no doubt) to 10 (really in doubt)
Over the past decade, computed tomography (CT) has become popular for management of scaphoid fractures. Increasingly, CT is used both to diagnose union and to estimate the percentage of the fracture gap that is bridged by healing bone.
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In the Journal of Hand and Microsurgery, though, Chaitanya S. Mudgal, MD, hand and upper extremity orthopedic surgeon, and colleagues suggest the latter use of only CT to estimate the percentage of the fracture gap that is bridged by healing bone may not be prudent. When they asked surgeons to review CT scans of scaphoid waist fractures, they noticed marked variability in the interpretations.
Study Design
The researchers invited selected members of the Science of Variation Group, an international research group of surgeons, to evaluate the extent of union of a scaphoid waist fracture on CT. Waist fractures were chosen because they are the most common type of scaphoid fracture treated by surgeons involved in fracture care.
All cases to be reviewed were retrieved from a single surgeon's practice. To minimize selection bias, the research team used a consecutive series of CT scans on adults with nondisplaced scaphoid waist fractures who were not treated surgically. The scans were made in the plane of the scaphoid, 10 to 12 weeks after injury.
Participants were shown videos of 13 CT scans in coronal and sagittal views. They were asked to eyeball the percentage and location of bony bridging. The percentage was to be categorized as 0%, 1%–24%, 25%–49%, 50%–74%, 75%–99% or 100%, and the location was to be categorized as dorsal, volar, radial or ulnar.
There was no restriction on how long the participants could view each video or the number of times they could view them.
The Surgeon Participants
140 surgeons completed a questionnaire and reviewed the videos. Most were specialists in hand and wrist surgery or traumatology. All participants said they treat at least one scaphoid fracture per year, with an average of 2.7 per year per participant.
Results
Interobserver agreement about the degree of partial union of the fractures was only fair (κ = 0.34). Agreement about the location of bony bridging was also only fair (κ = 0.31). The observers were asked to indicate their confidence in their answers on a scale of 0 to 10 (0 = no doubt and 10 = really in doubt), and the average was 3.8.
Clinical Implications
Surgeons should urge caution in using only imaging to guide treatment decisions, such as whether to perform surgery, in the presence of a partially united scaphoid fracture. Fracture tenderness also plays a role in treatment decisions and no research has investigated how well partial union on CT relates to fracture tenderness or lack thereof.
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