Anatomical-positional relationship between the bone structure of the distal radius and flexor pollicis longus tendon using ultrasonography.

PURPOSE: In this study, using an ultrasonography, we investigated the positional relationship between the volar bone cortex of distal radius and flexor pollicis longus (FPL) tendon in the distal radius of healthy subjects.

METHODS: The subjects were 32 healthy volunteers (56 wrists) (Age 32.9 ± 8.5, 16 males and 16 females). Their wrists were imaged by an ultrasonography. The distances between the watershed line (WS) and FPL (A), between the distal margin of pronator quadratus (DMPQ) and FPL (B), between the FPL and volar radial bone cortex at the maximum muscle belly of the PQ muscle right below the sliding region of the FPL tendon (C), and between the WS and DMPQ (D) were measured.

RESULTS: All these parameters showed a normal distribution. When the correlation among the parameters was investigated, a correlation with an index of the physique, BMI, was noted in A (P < 0.01), B (P < 0.01), and C (P < 0.01), but no correlation was noted only in D (P = 0.59).

CONCLUSIONS: Our results were suggested that when distal radius fracture is treated with a distal plate placement, the appropriate placement can be achieved by applying about 3 mm additional dissection of soft tissue on the volar bone cortex distal to the DMPQ.