The suction seal of the hip plays an important role in maintaining hip stability; however, the function of the ligamentum teres in maintaining this seal remains poorly understood. This study aimed to evaluate the effectiveness of the hip suction seal in ligamentum teres deficient hips for joint positions occurring during gait.
Six fresh-frozen human cadaveric hips were dissected and mounted to an Instron materials test system. Each specimen was analyzed for average peak distraction force, stiffness, and total energy during hip displacement. Testing was performed in the native intact ligamentum teres state and the deficient ligamentum teres state. Specimens were examined in 20° of flexion, neutral, and 10° of extension.
In the neutral position, the ligamentum teres deficient state displayed a significant decrease in peak distraction force (mean difference: 33.2 N, p < 0.001), average stiffness (mean difference: 63.7 N/mm, p = 0.016), and total energy (mean difference: 82.3 mJ, p = 0.022) compared to the intact controls. In extension, the deficient state exhibited a significant decrease in peak distraction force (mean difference: 42.8 N, p < 0.001) and total energy (mean difference: 72.9 mJ, p = 0.007). In flexion, the deficient state displayed a significant decrease in peak distraction force relative to contols (mean difference: 7.1 N, p = 0.003).
The ligamentum teres plays a significant role in maintaining the suction seal of the hip, with its effect being most prominent when the hip is in neural alignment or in extension. The findings suggest that ligamentum teres deficiency may be a relevant treatment target in the clinical setting.

UNASSIGNED: To investigate the correlation between glenohumeral joint congruence and stability in recurrent shoulder dislocations.
UNASSIGNED: Eighty-nine patients (89 sides) with recurrent shoulder dislocation admitted between June 2022 and June 2023 and met the selection criteria were included as study subjects. There were 36 males and 53 females with an average age of 44 years (range, 20-79 years). There were 40 cases of left shoulder and 49 cases of right shoulder. The shoulder joints dislocated 2-6 times, with an average of 3 times. The three-dimensional models of the humeral head and scapular glenoid were reconstructed using Mimics 20.0 software based on CT scanning images. The glenoid track (GT), inclusion index, chimerism index, fit index, and Hill-Sachs interval (HSI) were measured, and the degree of on/off track was judged (K value, the difference between HSI and GT). Multiple linear regression was used to analyze the correlation between the degree of on/off track (K value) and inclusion index, chimerism index, and fit index.
UNASSIGNED: Multiple linear regression analysis showed that the K value had no correlation with the inclusion index ( P>0.05), and was positively correlated with the chimerism index and the fit index ( P<0.05). Regression equation was K=-24.898+35.982×inclusion index+8.280×fit index, R 2=0.084.
UNASSIGNED: Humeral head and scapular glenoid bony area and curvature are associated with shoulder joint stability in recurrent shoulder dislocations. Increased humeral head bony area, decreased scapular glenoid bony area, increased humeral head curvature, and decreased scapular glenoid curvature are risk factors for glenohumeral joint stability.
UNASSIGNED: 探讨肩关节复发性脱位患者盂肱关节一致性与稳定性的相关性。.
UNASSIGNED: 以2022年6月—2023年6月收治且符合选择标准的89例（89侧）肩关节复发性脱位患者作为研究对象。其中，男36例，女53例；年龄20～79岁，平均44岁。左肩40例，右肩49例。脱位2～6次，平均3次。采用Mimics 20.0软件基于CT扫描图像重建肱骨头及肩胛盂三维模型，测算肩胛盂轨迹（glenoid track，GT）、包容指数、嵌合指数、契合指数、Hill-Sachs间隙（Hill-Sachs interval，HSI），并判断on/off track程度（K值，即HSI与GT差值）。采用多重线性回归分析on/off track程度（K值）与包容指数、嵌合指数、契合指数之间的相关关系。.
UNASSIGNED: 多重线性回归分析示，K值与包容指数无相关（ P>0.05），与嵌合指数、契合指数成正相关（ P<0.05）。回归方程：K=–24.898+35.982×嵌合指数+8.280×契合指数， R 2=0.084。.
UNASSIGNED: 肩关节复发性脱位中，肱骨头、肩胛盂骨性面积及曲率与肩关节稳定性相关。肱骨头骨性面积增大、肩胛盂骨性面积减小、肱骨头曲率增大、肩胛盂曲率减小是影响盂肱关节稳定性的危险因素。.

The distal radioulnar joint is not only the main load-bearing joint in the wrist, but also the pivot of the rotation of the forearm. It is one of the most important and unique joints in the body. Maintaining the stability of the distal radioulnar joint is very important for our daily life. The tissue to stabilize the distal radioulnar joint includes bone structures and soft tissue structures. Although the contribution of soft tissue structures to its stability is far exceeding that of bone structures, the influence of abnormal bone structure on the distal radioulnar joint cannot be ignored. By reviewing the relevant literatures, this article divides the bone structural abnormalities into congenital and acquired bone structural abnormalities. The effects of congenital and acquiredbone structural abnormalities on the distal radioulnar joint stability are analysized and collated in this article, and its clinical symptoms, clinical grading, clinical treatments are also summerized. The problems of distal radioulnar joint instability in clinical practicing and its future researching directions are briefly described in order to provide some suggestions for future clinical applications.

Treatment of posterior pelvic ring injuries is frequently associated with pain or/and high mortality rates. Percutaneous sacro-iliac (SI) screw fixation has proved to be one of the methods of choice, providing minimal operative time, blood loss and wound-related morbidity. However, fixation failures due to secondary fracture dislocation or screw backing out have been reported. There is a little knowledge regarding the impact of varying screw orientation and quality of reduction on the fixation strength.
The purpose of the present study was biomechanical investigation of joint stability after SI screw fixation and its dependence on quality of reduction and screw orientation.
Thirty-two artificial hemi-pelvices were assigned to four study groups and simulated SI dislocations were fixed with two SI screws in oblique or transverse screw orientation and anatomical or non-anatomical reduction in group A (oblique/anatomical), B (transverse/anatomical), C (oblique/non-anatomical) and D (transverse/non-anatomical). Mechanical testing was performed under progressively increasing cyclic axial loading until fixation failure. SI joint movements were captured via optical motion tracking. Fixation performance was statistically evaluated at a level of significance p = 0.05.
The highest cycles to failure were observed in group A (14038 ± 1057), followed by B (13909 ± 1217), D (6936 ± 1654) and C (6706 ± 1295). Groups A and B revealed significantly longer endurance than C and D (p ≤ 0.01).
Different screw orientations in the presented model do not influence substantially SI joint stability. However, anatomical reduction is not only mandatory to restore a malalignment, but also to increase the SI screw fixation strength and prevent fixation failures.

Stability of the thumb carpometacarpal joint relies upon equilibrium between its ligaments, muscular support and joint congruity. We wanted to identify the muscles important in preventing or increasing dorsoradial subluxation of this joint. In ten cadaveric hands, a Fastrak® motion tracking device was used to assess the effects of individual isometric muscle loading on the base of the thumb metacarpal relative to the radius and to the base of the middle finger metacarpal. We found that the first dorsal interosseous muscle caused the least dorsoradial translation and highest distal migration of the base of the first metacarpal, whereas abductor pollicis longus was the primary destabilizer, increasing dorsoradial misalignment. The findings show different impacts of these muscles on joint alignment and stability, which suggests that treatment should be targeted to enhance the action of the primary stabilizing muscle, the first dorsal interosseous muscle.

It has been reported that posterolateral corner structures, including the lateral collateral ligament, the popliteus tendon, and the popliteofibular ligament, may play important roles in reducing external rotational and posterior translational instabilities. However, there are few studies focusing on the quantitative influence of posterolateral corner structures on knee joint stability, due to the difficulty of controlling experimental conditions. In this study, a knee model that included posterolateral corner structures was developed. It was validated by comparison to previous experimental studies using the posterior drawer test, dial test, and varus stress test. The posterior translation, external rotation, and varus rotation were then predicted in order to investigate the contribution of posterolateral corner structures to translational and rotational stabilities. Our results indicate that posterolateral corner structures, including the popliteofibular ligament and the popliteus tendon, could contribute to posterior translational and external rotational stabilities, as clinical observations had suggested. Therefore, the addition of posterolateral corner structures to knee joint models may improve the utility of such models.