Ultrasound-based Measurement of the Intra-scaphoid angle.

Introduction: Ultrasound is gaining popularity for diagnosing scaphoid fractures. However, it hasn't been used to assess fracture displacement, such as humpback deformity. We propose a sonographic method to measure the intra-scaphoid angle, potentially serving as an alternative to CT scans for detecting fragment malposition after a scaphoid fracture.

Methods: We recruited 11 healthy adult volunteers without wrist pathology and performed bilateral wrist ultrasounds, totaling 22 examinations. Each wrist was splinted at 50 ° extension and fully supinated. Two hand surgeons independently performed the ultrasounds. All images were then evaluated separately by two evaluators. The following measurements were taken: 1. Inter-poles distance (IPD): Distance between the summits of the two scaphoid poles on the palmar cortex. 2. Palmar cortical intra-scaphoid angle (PCISA): Angle between the two summits and the deepest point of the waist on the palmar cortex. Measurements were compared for inter-investigator and inter-evaluator reliability using the intraclass correlation coefficient (ICC).

Results: The study included four males and seven females, with an average age of 35 years (range 21-56). The mean PCISA was 142 ° (SD 10 °) and the mean IPD was 16.3 mm (SD 2.1 mm). Differences in IPD measurements averaged 0.3 mm (range 0-5.2 mm) among investigators and 1.0 mm (range 0.1-3.8 mm) among evaluators. For PCISA, the differences averaged 4 ° (range 0-17 °) among investigators and 6 ° (range 0-15 °) among evaluators. The ICC for IPD was 0.804 (investigators) and 0.572 (evaluators); for PCISA, it was 0.704 (investigators) and 0.602 (evaluators).

Conclusion: This study presents a cost-effective and accessible sonographic technique to measure the intra-scaphoid angle. Further research is required to assess its effectiveness in scaphoid fractures and compare it to CT-based measurements like the H/L ratio, LISA, and DCA.