Changes in the flexor pollicis longus tendon during spontaneous resolution of pediatric trigger thumb.

The present study aimed to evaluate conformational changes in the flexor pollicis longus (FPL) tendon and inner space of the A1 pulley during spontaneous resolution of pediatric trigger thumb (PTT) and to compare them versus the normal contralateral side. We enrolled 36 patients with unilateral PTT who underwent ultrasonography twice between January 2016 and July 2020 and showed >10° improvement in thumb interphalangeal (IP) joint extension lag. Ultrasonography was used to measure the anteroposterior (AP) and radioulnar (RU) diameters of the FPL tendon proximal to the A1 pulley and of the inner space of the A1 pulley. On the side of the PTT, the average extension lag in the thumb IP joint significantly improved, from 35.6° to 14.2°. The AP and RU diameters of the FPL tendon increased by 0.3% and 1.9%, respectively, and those of the inner space of the A1 pulley increased by 15.3% and 5.0%, respectively. In the contralateral normal thumb, the AP and RU diameters of the FPL tendon increased by 12% and 9.3%, respectively, and those in the inner space of the A1 pulley increased by 9.9% and 4.6%. During improvement in IP joint extension lag, the mismatch between the enlarged FPL tendon and the inner space of the A1 pulley was reduced by their asymmetric growth.

A longitudinal histologic evaluation of vitamin D receptor expression in the skeletal muscles of patients with a distal radius fracture.

We investigated the effect of vitamin D supplementation on the expression of muscle vitamin D receptor (VDR) and cross-sectional area (CSA) in patients with a distal radius fracture (DRF). Significant increases in VDR expression and CSA were observed, especially in vitamin D-deficient patients. PURPOSE: Vitamin D supplementation is known to enhance muscle mass and function, but whether the VDR is essential in this process remains unknown. We evaluated the change in VDR expression and CSA in the forearm muscles following vitamin D supplementation in patients with a DRF. METHODS: We prospectively recruited 18 women with a median age of 63.5 years who have a DRF. We obtained two biopsies of the forearm muscle, first at the time of fracture repair and then during hardware removal. We supplemented 1000 IU of vitamin D per day during a median interval of 8 months. We examined the changes in VDR expression and CSA by immunohistochemistry. RESULTS: The median serum 25-hydroxyvitamin D [25(OH)D] increased from 14.3 to 32.1 ng/mL (P = 0.001). The median VDR expression increased from 0.72 to 0.78 (P = 0.002), and the median CSA increased from 1290.0 to 1685.8 µm2 (P = 0.022). Significant increases in VDR expression and CSA were observed in vitamin D-deficient patients [25(OH)D] < 20 ng/mL, but not in vitamin D-non-deficient patients. The changes in VDR expression and CSA were in the same direction in 13 patients, but in the opposite direction in 5 patients. CONCLUSION: Vitamin D supplementation may increase muscle VDR expression and CSA in patients with a DRF, especially in vitamin D-deficient patients. The increase in CSA without an increase in VDR expression in some patients indicates that the effect of vitamin D supplementation on muscle mass could be mediated by indirect effect of serum vitamin D restoration and by VDR.