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Background: Despite the movement of the thumb carpometacarpal joint has been studied, many unclarified points remain regarding the movement of this joint. The purpose of this study was to evaluate the in vivo kinematics of the thumb carpometacarpal joint during flexion and abduction using computed tomography images. Methods: The subjects were 9 healthy males. Computed tomography images were obtained in 4 equally-divided positions from maximum extension to maximum flexion, and maximum adduction to maximum abduction of the thumb. A three-dimensional model was constructed from these images, and the models of each position were superimposed with reference to the trapezium. The amount of angular change around the bone axes of first metacarpal bone and rotation axes were evaluated. Results: We found that the first metacarpal bone showed relatively simple behavior during abduction. However, during flexion, it exhibited a particular movement in which the amount of angular change of the metacarpal bone with respect to the trapezium rapidly increased with deep flexion. Conclusions: These results suggest that the thumb carpometacarpal joint exhibits a special movement during flexion, especially deep flexion. [ABSTRACT FROM AUTHOR]

Background: We made a tin ring splint for osteoarthritis of the distal interphalangeal joint that looks attractive and is easy to wear. We report the treatment results with this splint. Methods: We enrolled 30 patients with painful osteoarthritis of the distal interphalangeal joint in this study. A tin ring splint was made with tin alloy containing small quantities of silver. Patients were instructed to wear the splint when they felt pain. Patients were assessed before splint use and after 1, 3, and 6 months of splint use. Endpoints included the numeric pain scale, active arc of motion of the distal interphalangeal joint, Hand 20, functional assessment criteria of the upper extremities, and treatment satisfaction. In addition, data were collected on time to symptom relief and satisfaction related to usability and appearance of the splint (0 = dissatisfied, 10 = satisfied). Results: The numeric pain scale showed significant pain improvement from 58.4 ± 4.1 at baseline to 33.1 ± 4.5 at 1 month, and the Hand 20 score also showed significant improvement from 35.0 ± 4.3 at baseline to 20.2 ± 3.2 after 6 months. Active arc of motion were not changed significantly. Most patients responded that symptoms were relieved by the 10th day after treatment. Satisfaction related to usability was 8.9 ± 0.3, and appearance was 7.6 ± 0.4. Conclusions: A tin ring splint quickly reduced pain, and satisfaction related to usability and appearance was high. This splint could be one choice for conservative treatment of osteoarthritis of the distal interphalangeal joint. [ABSTRACT FROM AUTHOR]

Background: Despite the movement of the thumb carpometacarpal joint has been studied, many unclarified points remain regarding the movement of this joint. The purpose of this study was to evaluate the in vivo kinematics of the thumb carpometacarpal joint during flexion and abduction using computed tomography images. Methods: The subjects were 9 healthy males. Computed tomography images were obtained in 4 equally-divided positions from maximum extension to maximum flexion, and maximum adduction to maximum abduction of the thumb. A three-dimensional model was constructed from these images, and the models of each position were superimposed with reference to the trapezium. The amount of angular change around the bone axes of first metacarpal bone and rotation axes were evaluated. Results: We found that the first metacarpal bone showed relatively simple behavior during abduction. However, during flexion, it exhibited a particular movement in which the amount of angular change of the metacarpal bone with respect to the trapezium rapidly increased with deep flexion. Conclusions: These results suggest that the thumb carpometacarpal joint exhibits a special movement during flexion, especially deep flexion.

Introduction: We previously reported the classification of the scaphoid fracture nonunions as linear, cystic, and sclerotic or displaced types based on radiographic findings. We have been treating the linear and cystic type fractures via screw fixation without bone grafting and the sclerotic or displaced type fractures via screw fixation with bone grafting. In this retrospective study, we report the treatment outcomes of the linear and cystic types of scaphoid fracture nonunions., Methods: Nineteen patients with linear and cystic type scaphoid fracture nonunions were included. Two patients had linear type and 17 had cystic type fractures. All the patients were male, their mean age was 29.2 years. All patients were treated with screw fixation alone by a single surgeon., Results: Bone union was achieved in 17 cases. The mean time to bone union was 3.7 months. Bone union was not achieved in one case of linear type and one case of cystic type fracture. The former was thought to be due to misdiagnosis of displaced type as linear type fracture; however, no obvious reason could be found for the latter., Discussion: Screw fixation alone could help achieve bone union in linear type scaphoid fracture nonunions. However, if the type of the fracture is difficult to diagnose based on plain radiography, evaluation using computed tomography should be performed. The cystic type fractures may need to be subclassified according to the location or size of the cyst as well as the viability of the proximal bone fragment., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper.The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article., (© 2020 Delhi Orthopedic Association. All rights reserved.)