Ulnar Variance in Scaphoid Fractures: Retrospective Analysis of 182 Cases

Area of Science:

• Orthopedic surgery
• Radiology
• Biomechanics

Background:

• Limited and conflicting evidence exists on the relationship between ulnar variance (UV) and scaphoid fracture incidence.
• Ulnar variance, the relative length of the ulna compared to the radius at the wrist, is a potential factor in wrist injuries.

Purpose of the Study:

• To investigate the association between ulnar variance and acute scaphoid fractures.
• To compare ulnar variance measurements in patients with scaphoid fractures versus a control group with wrist contusions.

Main Methods:

• A retrospective study involving 182 patients with acute scaphoid fractures and 182 matched controls with wrist contusions.
• Standardized digital wrist radiographs were used to measure ulnar variance using the method of perpendiculars.
• Measurements were performed by two independent examiners to ensure reliability.

Main Results:

• Excellent inter-rater reliability (ICC=0.93) was achieved for UV measurements.
• The mean UV was significantly lower (more negative) in the scaphoid fracture group (-0.82 mm) compared to the control group (0.27 mm).
• A statistically significant difference (p < 0.0001) was found between the UV values of the two groups.

Conclusions:

• Patients sustaining scaphoid fractures are significantly more prone to exhibit negative ulnar variance.
• Negative ulnar variance may be a predisposing factor for acute scaphoid fractures.
• Further research could explore the biomechanical implications of negative UV in scaphoid injury.