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.