An anatomical study of the arcade of Frohse and the relationship with posterior interosseous nerve entrapment syndrome.

PURPOSE: To demonstrate the anatomical characteristics of the arcade of Frohse (AF) and the deep branch of the radial nerve (DBRN), so as to provide a valuable anatomical reference for the relationship with posterior interosseous nerve entrapment syndrome (PINS).

METHODS

Fifty human upper limbs were dissected to observe the AF and DBRN. The width and height of AF and the length of the supinator canal (SCL) were measured.

RESULTS

Based on the morphological characteristics, the AF was classified into: U-type in 24 cases; hook-type in 18 cases; and linear-type in 8 cases. According to the branching number of DBRN, they were classified into: Type Ⅰ, the DBRN entered and exited the supinator canal both as a single nerve in 37 cases; Type Ⅱ, the DBRN entered supinator canal as a single nerve, and exited as two branches in 7 cases; Type Ⅲ, the DBRN entered supinator canal as two nerves, and exited as one nerve in 2 cases; Type Ⅳ, the DBRN entered and exited the supinator canal both as two nerves in 2 cases; Other rare branching variants: two extremely rare patterns were grouped here, with 1 case for each pattern. Rare type A: the DBRN entered supinator canal as four nerves, exited as three nerves in 1 case. Rare type B: the DBRN entered supinator canal as three nerves, but exited as one nerve in 1 case. The width and height of AF were 16.06 ± 5.27 mm (range: 5.08-27.92 mm) and 12.14 ± 4.17 mm (range: 4.14-23.27 mm), respectively. The length of the supinator canal was 38.28 ± 6.06 mm (range: 26.11-52.27 mm).

CONCLUSION

This study proposed new classifications for the AF and the DBRN. Rare branching variations of the DBRN were identified, and these findings may serve as a reference for the clinical diagnosis and treatment of PINS.