LAUSR

Background: Carpal tunnel syndrome is occasionally associated with basal joint arthritis and is more common in postmenopausal women than in the general population. Currently, more evidence is needed to describe changes in the carpal tunnel after basal joint arthroplasty (BJA) of the thumb and to determine whether it is better to combine the release of the flexor retinaculum. The purpose of this study was to clarify the changes in the carpal tunnel cross-sectional area and carpal tunnel shape after complete removal of the trapezium during BJA of the thumb, according to computed tomography (CT) findings. Methods: We retrospectively investigated the carpal tunnel cross-sectional area with CT findings obtained pre- and postoperatively in 20 postmenopausal women who underwent BJA of the thumb. Results: The average horizontal plane area of the carpal tunnel was 1.11 ± 0.19 cm2 preoperatively and increased to 1.23 ± 0.2 cm2 at 3 months postoperatively (p = 0.0411). The ratio of the longitudinal diameter to the horizontal diameter was significantly increased from 0.6 ± 0.13 preoperatively to 1.23 ± 0.2 postoperatively (p = 0.0439). Conclusions: The increase in the carpal tunnel cross-sectional area was confirmed after BJA of the thumb. This increased carpal tunnel cross-sectional area changed as the longitudinal diameter increased, without changes in the horizontal diameter. Level of Evidence: Level IV (Therapeutic).