Measuring Angulation on Distal Radius Fracture
Angulation on distal radius fractures is primarily measured using palmar tilt (also called dorsal/palmar tilt) on the lateral radiographic view, with standard measurements requiring a minimum of three radiographic views (posteroanterior, lateral, and 45° semipronated oblique view) for accurate assessment. 1
Standard Radiographic Views Required
For proper assessment of distal radius fractures, the following radiographic views are necessary:
- Posteroanterior (PA) view
- Lateral view
- 45° semipronated oblique view 1
Some evidence suggests that adding a fourth projection (semisupinated oblique) can increase diagnostic yield for distal radius fractures 1.
Key Angulation Measurements
1. Palmar Tilt (Primary Angulation Measurement)
- Measured on the lateral view
- Normal value: 11-12° volar (palmar) tilt
- Measured as the angle between:
- Reliability: High intra-observer and high inter-observer reliability 2, 3
- Error margin: 6-8° 2
2. Radial Angle (Radial Inclination)
- Measured on the PA view
- Normal value: 22-23°
- Measured as the angle between:
- Reliability: Moderate intra-observer and moderate inter-observer reliability 2, 3
- Error margin: 6-8° 2
Technical Considerations for Accurate Measurement
Rotation Effects on Measurements
- A 5° rotational change in forearm position produces:
- 1.6° change in palmar tilt on conventional lateral view
- 1.0° change in palmar tilt on 15° lateral view 4
- Lateral radiographs can be rotated 15-30° and still be considered acceptable, potentially causing up to 6.4° error in palmar tilt measurement 4
Improving Measurement Accuracy
- Using a 15° lateral view provides clearer measuring landmarks and minimizes error due to rotation for fractures with significant dorsal angulation 4
- Digital radiographs with measurement software improve reliability:
- Improves interobserver reliability of palmar tilt from substantial to excellent
- Improves measurement of radial height from moderate to substantial 5
Reliability of Measurements
Research shows varying reliability for different measurements:
High reliability (ICC > 0.80)
- Palmar tilt (inter-observer)
- Dorsal shift and palmar tilt (intra-observer) 2
Moderate reliability (ICC 0.60-0.80)
- Dorsal shift, ulnar variance, radial angle, radial height (inter-observer)
- Radial angle, radial height, ulnar variance, radial shift (intra-observer) 2
Low reliability (ICC < 0.60)
- Radial shift, intra-articular gap and step (inter-observer)
- Intra-articular gap and step (intra-observer) 2
Clinical Implications
Successful treatment of distal radius fractures requires restoration of:
- Radial length
- Inclination
- Tilt
- Realignment of articular fracture fragments 1
Operative fixation is typically considered necessary when there is:
2 mm of residual articular surface step-off to avoid long-term complications like osteoarthritis 1
- Coronally oriented fracture line
- Die-punch depression
- More than three articular fracture fragments 1
Pitfalls to Avoid
Inadequate views: Using only 2 radiographic views is not adequate for detecting fractures, especially for wrist, hand, and finger injuries 1
Measurement of small intra-articular gaps and steps: Clinicians cannot reliably measure values ≤1 mm for intra-articular gap and step using standard radiographic methods 2
Forearm rotation errors: Inconsistent positioning during radiography can significantly affect palmar tilt measurements 4
Relying solely on radiographs for complex fractures: CT shows intra-articular extension more frequently than radiography and 3D reconstructions can be helpful for preoperative planning of complex articular injuries 1
For scientific purposes, CT-based methods provide higher reliability when measuring changes in dorsal angulation in distal radius fractures compared to conventional radiography 6.