BackgroundThe physical and biochemical factors responsible for cervical disc degeneration, and resulting in various spinal disorders, remain unclear. This study aimed to evaluate the correlation between cervical spinal canal stenosis and degeneration of intervertebral discs, and to analyze the factors related to disc degeneration in the Japanese population.MethodsThree hundred and forty-four Japanese general residents underwent investigations, including magnetic resonance imaging of the cervical spine, in our health check project. We measured anteroposterior diameters at the levels of the cervical spinal disc in mid sagittal plane magnetic resonance imaging and evaluated disc degeneration. Spearman correlation coefficient was used to evaluate whether the diameters were correlated with disc degenerative scores. Stepwise multiple linear regression analysis was conducted with the score of disc degeneration as the dependent variable; and age, physical measurement values, bone mineral density of the forearm, and the value of serum bone metabolic markers and amino acids as the independent variables for each sex.ResultsAs the age increased, the anteroposterior diameters decreased in both sexes. The minimum anteroposterior diameters were correlated with the disc degenerative scores (Spearman r = − 0.59, p < 0.001 in men, Spearman r = − 0.53, p < 0.001 in women). In multiple linear regression analysis, age, cross-linked N-telopeptide of type 1 collagen and isoleucine were significantly correlated with the cervical disc degenerative score in men (R2 = 0.47), and age and lysine were significantly correlated with the degenerative score in women (R2 = 0.50).ConclusionThe factors responsible for cervical disc degeneration differed between men and women. Whether modifying these significant factors is possible, or whether this intervention would contribute to prevention of disc degeneration requires future studies.

Background Repetitive mechanical stress on the elbow joint during throwing is a cause of ulnar collateral ligament dysfunction that may increase the compressive force on the humeral capitellum. This study aimed to examine the effects of ulnar collateral ligament material properties on the humeral capitellum under valgus stress using the finite element method. Methods Computed tomography data of the dominant elbow of five healthy adults were used to create finite element models. The elbows were kept at 90° of flexion with the forearm in the neutral position, and the ulnar collateral ligament was reproduced using truss elements. The proximal humeral shaft was restrained, and valgus torque of 40 N·m was applied to the forearm. The ulnar collateral ligament condition was changed to simulate ulnar collateral ligament dysfunction. Ulnar collateral ligament stiffness values were changed to 72.3 N/mm, 63.3 N/mm, 54.2 N/mm, 45.2 N/mm, and 36.1 N/mm to simulate ulnar collateral ligament laxity. The ulnar collateral ligament toe region width was changed in increments of 0.5 mm from 0.0 to 2.5 mm to simulate ulnar collateral ligament loosening. We assessed the maximum equivalent stress and stress distribution on the humeral capitellum under these conditions. Results As ulnar collateral ligament stiffness decreased, the maximum equivalent stress on the humeral capitellum gradually increased under elbow valgus stress ( P < .001). Regarding the change in the ulnar collateral ligament toe region width, as the toe region elongated, the maximum equivalent stress of the humeral capitellum increased significantly under elbow valgus stress ( P < .001). On the capitellum, the equivalent stress on the most lateral part was significantly higher than that on other parts ( P < .01 for all). Conclusion Under elbow valgus stress with elbow flexion of 90° and the forearm in the neutral position, ulnar collateral ligament dysfunction increased equivalent stress on the humeral capitellum during the finite element analysis. The highest equivalent stress was noted on the lateral part of the capitellum.

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Background: Osteochondritis dissecans (OCD) of the humeral capitellum occurs in adolescent overhead athletes, and medial epicondyle (ME) lesions are also common in this population. Purpose: To evaluate the association between elbow OCD and ME lesions in adolescent baseball players. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This study retrospectively evaluated adolescent baseball players with unstable elbow OCD who underwent surgery between January 2000 and February 2020. Patients were excluded if they had osteoarthritis of the elbow. A total of 139 elbows were included in this study (138 male and 1 female athlete; mean ± SD age, 13.6 ± 1.5 years). The patients were first divided into 2 groups based on OCD location: a central lesion group (72 elbows) and a lateral group (67 elbows). Next, patients were divided according to OCD size into a localized group (56 elbows) and a widespread group (83 elbows). Finally, OCD lesions that were both lateral and widespread were defined as lateral-widespread (60 elbows), resulting in 5 groups. ME apophyseal fragmentation and elongation were evaluated and defined as ME lesions. We then compared the relationship between OCD and ME lesions. Results: Of the 139 elbows, 63 (45.3%) had ME lesions. The prevalence of ME lesion was higher in the lateral group than the central group (56.7% vs 34.7%; P = .009) and higher in the widespread group than the localized group (55.4% vs 30.4%; P = .004). Furthermore, the prevalence ratio of ME lesion was significantly higher in the lateral-widespread group than for other lesions (58.3% vs 35.4%; P = .007). Conclusion: In patients undergoing surgery for capitellar OCD, the presence of ME lesions was more commonly associated with lateral and widespread capitellar lesions when compared with central and localized lesions.