正畸治疗后满意病例牙齿转矩角的三维测量研究

目的 :研究不同错牙合分类病例矫治满意后 ,牙齿转矩与自然正常牙合的差异 ,为临床上牙齿转矩的调整提供参考。方法 :选择正畸治疗后满意病例 15 7例 ,用YM 2 115型三维测量仪对治疗后模型进行牙齿转矩测量 ,与自然正常牙合的相应数据进行比较分析。结果 :安氏Ⅰ类错牙合矫治后满意病例上下切牙转矩最接近自然正常牙合 ,上中切牙、侧切牙的转矩分别为 9.6°和 8.7°;下中切牙、侧切牙转矩分别为 1.1°和 - 1.1°。安氏Ⅱ类错牙合矫治后满意病例上切牙的转矩与正常牙合无明显差异 ,而下切牙转矩明显较为唇倾 ,为 5 .6°和 2 .1°。安氏Ⅲ类的差异更为明显 ,上切牙唇倾达 15 .2°和 12 .1° ;下切牙舌倾达 - 3.7°和 - 4 .9°。结论 :要想通过正畸方法矫治安氏Ⅱ类和Ⅲ类错牙合达到正常的覆牙合覆盖 ,上下切牙的转矩必须做出适当的调整以作补偿     

Differences in quadriceps muscle strength and fatigue between lean and obese subjects

The present study aimed to compare quadriceps femoris muscle strength and fatigue between obese (grade II and III) and nonobese adults. Ten obese (mean age: 25 years; mean BMI: 41 kg/m2) and ten lean (mean age: 27 years; mean BMI: 23 kg/m2) men were tested. Quadriceps muscle fatigue was quantified as the (percent) torque loss during a voluntary isokinetic (50 maximal contractions at 180°/s) and an electrostimulated (40 Hz) isometric protocol (5 min, 10% of the maximal torque). Maximal voluntary isometric and isokinetic torque and power were also measured. Voluntary torque loss was significantly higher (P < 0.05) in obese (−63.5%) than in lean subjects (−50.6%). Stimulated torque decreased significantly (P < 0.05) but equally in the two subject groups. Obese subjects displayed higher absolute (+20%; P < 0.01) but lower relative (i.e., normalized to body mass) (−32%; P < 0.001) muscle torque and power than their lean counterparts. Obese individuals demonstrated lower fatigue resistance during voluntary but not during stimulated knee extensions compared to their nonobese counterparts. Peripheral mechanisms of muscle fatigue—at least those associated to the present stimulated test—were not influenced by obesity. The observed quadriceps muscle function impairments (voluntary fatigue and relative strength) probably contribute to the reduced functional capacity of obese subjects during daily living activities.     

Joint position dependence of weakness during maximum isometric voluntary contractions in subjects with hemiparesis

OBJECTIVE: To determine the distribution of weakness across elbow range of motion (ROM) in subjects with hemiparesis. DESIGN: A detailed analysis of elbow torque and associated electromyographic signals of 5 prime elbow muscles generated during maximum isometric voluntary flexion (MIVF) and extension (MIVE) at 8 different elbow positions. SETTING: Rehabilitation center research laboratory. PARTICIPANTS: Convenience samples of 5 controls and 10 subjects with hemiparesis with sufficient passive (>90 degrees ) and active (>60 degrees ) ROM on their paretic side. INTERVENTIONS: Not applicable. Main Outcome Measures: Measured and normalized MIVF and MIVE torques and normalized moving average electromyographic signals of each muscle at each testing position. RESULTS: Measured MIVF and MIVE torques generated by the hemiparetic group were marginally and significantly smaller than those of the control group (2-factor repeated-measures analysis of variance [ANOVA]: P=.053 for MIVF, P=.011 for MIVE). Distribution of weakness was nonuniform across elbow positions, as shown by normalized torque-position curves. Normalized MIVE torque of the hemiparetic group was significantly and marginally smaller than that of the control group at 15 degrees and 30 degrees (Student t test: P<.0001, P=.054), respectively. Although statistically not significant, the normalized MIVF torque of the hemiparetic group was slightly larger than that of the control group but became smaller than the control group's as the elbow flexed beyond 90 degrees. Our electromyographic recordings supported the normalized MIVF torque findings, showing a significant increase in brachioradialis activation in the control group at flexed positions during MIVF (1-factor repeated-measure ANOVA, P=.003), but not in the hemiparetic group (P=.392). CONCLUSION: Our findings suggest that measuring the strength in multiple joint positions is useful for characterizing the basic changes in muscle activation strategies and properties and provides a relevant measure of elbow weakness from a clinical and functional perspective. Various mechanisms of action are discussed to better understand the relation between joint position and weakness.     

不同槽沟方向舌侧托槽转矩控制性能三维有限元分析

目的分析不同槽沟方向的舌侧托槽转矩控制性能以及不同弓丝尺寸、材质对其转矩的影响规律。方法建立上颌前牙垂直槽沟及水平槽沟舌侧托槽、3种材质(不锈钢弓丝、β钛丝、镍钛丝)、2种尺寸(0.43 mm×0.56 mm、0.41 mm×0.56 mm)弓丝的有限元模型,对左上颌中切牙施以±20°的转矩加载,分析对比其力学性能。结果随着弓丝弹性模量的增大,不同槽沟方向的舌侧托槽转矩力矩逐渐增大;槽沟方向对舌侧托槽的转矩性能有影响,但小于弓丝尺寸及材质变化带来的影响。相同转矩角度下,垂直槽沟舌侧托槽产生约为水平槽沟舌侧托槽1~2倍的转矩力。弓丝尺寸对两种托槽转矩控制的影响小于弓丝材质,两者协同变化影响最大。结论槽沟方向、弓丝尺寸、材质改变均能影响舌侧托槽转矩控制性能。临床应用中,可以根据所需转矩力大小,对舌侧托槽槽沟方向及弓丝尺寸、材质组合进行选择。     

Cervical range of motion and strength in 4,293 young male adults with chronic neck pain

Purpose

The correlation of cervical biomechanics and neck pain in young patients has, to date, only been described in terms of small cohorts. This study focuses on the correlation of chronic neck pain and cervical biomechanics.

Methods

Neck pain, cervical range of motion (CROM) and maximal cervical torque were recorded in 746 patients with conservatively treated chronic neck pain and 3,547 participants of physiotherapy training without chronic neck pain aged 16–32 years.

Results

The “neck pain” group had a highly significant (s < 0.001) higher neck disability index (44.7 vs. 10.4 %), longer history of neck pain (3.47 vs. 0.59 years), higher pain intensity (VAS 5.93 vs. 0.93), higher pain frequency (VAS 6.98 vs. 1.09). No differences of CROM and maximal torque in the sagittal, frontal and transverse plane were found.

Conclusion

This study describes the largest cohort of biomechanical data of the cervical spine in young adult recorded to date. The findings demonstrate that no correlation was found between neck pain, CROM and maximal torque in the study cohort. On this basis, we conclude that the CROM and maximal cervical torque should not be used as indicators to measure the progress of chronic neck pain in physiotherapy training and sports medicine for the young adult.     

An analysis of symmetry of torque strength of the forearm under resisted forearm rotation in normal subjects

PURPOSE: To establish normative pronation and supination torque values in right-handed adults without evidence of upper-extremity dysfunction or impairment in the forearm positions of neutral, pronation, and supination. METHODS: Fifty-one normal right-handed participants ages 22 to 45 years were enrolled and tested in this study using a custom device that incorporated a torque cell and a grip system that produced a digital recording of the peak torque during maximal resisted pronation and supination in positions of neutral forearm rotation, 60 degrees pronation, and 60 degrees supination. RESULTS: The greatest peak torque strength for both male and female participants was found during resisted pronation in the supinated position. The peak torque values averaged 11.9 +/- 3.7 N.m on the right side and 10.4 +/- 3.3 N.m on the left side for men, and 6.0 +/- 1.4 N.m on the right side and 5.0 +/- 1.2 N.m on the left side for women. The weakest torque strengths were resisted pronation in the pronated position and resisted supination in the supinated position. CONCLUSIONS: Torque strength measurements are reliable and should be collected when treating patients with forearm dysfunction. Maximal torque follows the same pattern related to hand dominance as grip strength. Men generate average torque strengths that are approximately twice the magnitude of those generated by women.     

Evaluation of torque moment in esthetic brackets from bendable alloy wires

ObjectivesTo examine the torque moment that occurs between esthetic brackets and bendable alloy (stainless steel [SS], titanium-molybdenum [Ti-Mo], and titanium-niobium [Ti-Nb]) wires.Materials and MethodsThis study examined ceramic (CR), zirconium oxide (ZC), polycarbonate (PC), and conventional metallic brackets (MT) (upper, 0.018-inch and 0.022-inch slots) combined with SS, Ti-Mo, and Ti-Nb wires using elastic module ligation. The torque moments delivered by various wire and bracket combinations were measured using a torque gauge apparatus. The wire torque angles at 5–40° were examined.ResultsThe torque value increased in the order of CR, ZC, MT, and PC brackets for both 0.018-inch and 0.022-inch slots. The fracture points of the CR and ZC brackets combined with SS and Ti-Mo wires were approximately more than 30° and 35°, respectively. No fracture points were detected in the combination of ZC brackets and Ti-Nb wires.ConclusionsThe current study identified the material characteristics of CR, ZR, and PC brackets during torque tooth movements. The present results demonstrate a characteristic combined effect between different esthetic brackets and bendable alloy wires.     

膝骨性关节炎患者股四头肌峰力矩与疼痛程度相关性研究

目的：探讨膝骨性关节炎患者股四头肌峰力矩与疼痛程度的相关性.方法：在速度为120°/s的条件下,用美国Biodex等速测力系统测定30例男性膝骨性关节炎患者股四头肌峰力矩（PT）;并在等速训练前、后用视觉模拟量表（VAS）测定患者疼痛评分,取其平均值;将测得的PT值与疼痛评分值进行线性相关分析;若相关分析有直线趋势时进行回归分析.结果：PT值与疼痛评分具有较高相关性,r=-0.910 4（P＜0.01）.结论：股四头肌峰力矩越大,患者疼痛评分越小,二者呈线性负相关性.     

Isokinetic dynamometry applied to shoulder rotators – Velocity limitations in eccentric evaluations

The objectives of this study were to evaluate if collegiate overhead athletes, with and without shoulder pain, and non-athletes could reach a preset velocity in internal and external shoulder rotation isokinetic evaluations; and to evaluate the correlation between torque and velocity. Controlled laboratory study, cross-sectional. Evaluations were performed using the isokinetic dynamometer Biodex System 3. Participants were assessed seated, with the arm at 90° of shoulder abduction and 90° of elbow flexion, from neutral rotation to 90° of external rotation. Five maximal contractions of isokinetic concentric and reactive eccentric internal and external rotation were performed at the velocities 90°/s, 180°/s and 240°/s. Data were processed with using MatLab. Most participants did not reach the isokinetic phase during eccentric tests at 180°/s and 240°/s, particularly in the external rotators evaluation. High correlations between torque and velocity of eccentric tests were found. The groups presented no differences in maximal velocity attained in trials which preset velocity was not reached. These results call into question the use of reactive eccentric tests at velocities higher than 180°/s for the isokinetic evaluation of shoulder external rotators in collegiate overhead athletes and non-athletes in this specific position. In such cases, careful evaluation of the velocity is recommended to determine if the isokinetic phase was reached.