Distinct Wrist Patterns Founded on Measurements in Plain Radiographs

Area of Science:

• Orthopedics
• Radiology
• Anatomy

Background:

• Wrist structure is crucial for function and pathology, but its complexity and anatomical variability pose interpretation challenges.
• Previous research identified two distinct patterns in the midcarpal joint based on lunate and capitate shapes.
• Understanding these patterns is key to diagnosing and treating wrist conditions.

Purpose of the Study:

• To further characterize the two identified wrist anatomical patterns in normal adult wrist radiographs.
• To analyze joint contact and position measurements to differentiate between these patterns.
• To test the hypothesis that significant differences exist between the two distinct anatomical patterns.

Main Methods:

• Evaluation of 172 normal adult posteroanterior (PA) wrist radiographs.
• Measurement of parameters including radial inclination, ulnar variance, and lunate and capitate types.
• Calculation of the articulating facet percentages between carpal bones and comparison between wrist types.

Main Results:

• Type-1 wrists (lunate type-1, spherical proximal capitate) showed a longer facet between the capitate and distal lunate (p=0.01) and capitate and base of middle metacarpal (p=0.004).
• Type-1 wrists had a shorter facet between the capitate and hamate (p=0.004).
• Increased odds of Type-1 wrist were observed with specific capitate-lunate (OR 2.71) and capitate-metacarpal (OR 3.5) interface measurements.

Conclusions:

• Two distinct wrist anatomical patterns were successfully characterized using intracarpal measurements.
• These identified differences in joint morphology provide a basis for understanding wrist biomechanics.
• Translating these findings into 3D contact areas may enhance the comprehension of force transmission through the wrist.