High-resolution ultrasound of the annular pulley system in the toes: sonographic anatomy and pathological cases.

Abstract

Objective: To validate high-frequency ultrasound as a valuable imaging modality in the assessment of the annular pulley system of the toes, describing their normal sonographic appearance and presenting some illustrative pathological cases.

Materials and methods: The first phase of this observational study involved examining the annular pulley system of the flexor tendons of the toes in a series of cadaveric specimens, testing the ability of ultrasound to recognize these structures. In the second phase, two expert sonographers examined a sample of 15 healthy adult participants using two different 18-5 MHz and 24-8 MHz linear array ultrasound probes. Sonographic visibility, position, and maximal thickness of each annular pulley were assessed.

Results: In the cadaveric study, ultrasound provided identification of 4 annular pulleys in the lesser toes and 3 in the great toe across 8 feet from 4 cadavers. In 30 feet of 15 healthy participants, ultrasound was able to consistently recognize and measure the annular pulleys of toes I-IV, with minimal variability between operators. The V toe annular pulleys were less reliably visualized. The intraclass correlation coefficient (ICC) analysis of pulley maximal thickness measurements between the two sonographers showed moderate agreement for the 24-8 MHz probe with a mean ICC of 0.393 (CI: 0.315-0.471) and better agreement for the 18-5 MHz probe with a mean ICC of 0.529 (CI: 0.442-0.616).

Conclusion: This study provides a comprehensive description of the sonoanatomy of the annular pulleys of the flexor tendons in the toes and demonstrates the potential of ultrasound as a valuable tool for diagnosing pathologies of these structures.