3D kinematics of the glenohumeral joint during abduction motion: an ex vivo study

The clinical tolerance of rotator cuff tears is extremely variable, so the question is, what is the role of the deltoid in the shoulder stability? First of all, ex vivo experiments are necessary to analyse its effect. The aims of this study were: (1) to propose a testing protocol to measure the glenohumeral joint kinematics during the abduction motion by pulling on the deltoid without constraining the humerus and (2) to evaluate the repeatability of the 3D measurements. Six fresh-frozen anatomic specimens were tested. The kinematics follow-up of the osseous parts was carried out using an optoelectronic system (Polaris^®, NDI, Canada). The abduction motion is realized by the pulling on anterior and medium fibers of the deltoid. For a 25 mm displacement, the range of motion: for the abduction was 24° to 30.5°, for the flexion was 1.5° to ?30.5° (extension), for the medio-lateral rotation was 12° (lateral rotation) to ?5° (medial rotation). For a displacement of the whole acromion-clavicle between 0 and 25 mm, the three humeral head translations were less than 5 mm. The three rotations and three translations were (with SD 95%): abduction: 0.5°, flexion: 1°, medio-lateral rotation: 1.5°, three translations: 0.5 mm. The results showed a very high repeatability of the values. Results suggest that the deltoid alone can realize a motion of lateral elevation with a good stability in the glenohumeral joint as shown by the slight translation motion of the head and the value reproducibility. The protocol can be used to validate a finite element model of the glenohumeral joint.     

Predictive Simulations of Neuromuscular Coordination and Joint-Contact Loading in Human Gait

We implemented direct collocation on a full-body neuromusculoskeletal model to calculate muscle forces, ground reaction forces and knee contact loading simultaneously for one cycle of human gait. A data-tracking collocation problem was solved for walking at the normal speed to establish the practicality of incorporating a 3D model of articular contact and a model of foot–ground interaction explicitly in a dynamic optimization simulation. The data-tracking solution then was used as an initial guess to solve predictive collocation problems, where novel patterns of movement were generated for walking at slow and fast speeds, independent of experimental data. The data-tracking solutions accurately reproduced joint motion, ground forces and knee contact loads measured for two total knee arthroplasty patients walking at their preferred speeds. RMS errors in joint kinematics were?<?2.0° for rotations and?<?0.3 cm for translations while errors in the model-computed ground-reaction and knee-contact forces were?<?0.07 BW and?<?0.4 BW, respectively. The predictive solutions were also consistent with joint kinematics, ground forces, knee contact loads and muscle activation patterns measured for slow and fast walking. The results demonstrate the feasibility of performing computationally-efficient, predictive, dynamic optimization simulations of movement using full-body, muscle-actuated models with realistic representations of joint function.     

The placement of skin surface markers for non-invasive measurement of scapular kinematics affects accuracy and reliability

Abnormal scapular movement is widely believed to be an important factor in clinical pathology of the shoulder joint complex. Validated non-invasive techniques for measuring scapular movement have been developed, but the effect of marker placement on accuracy is unknown. The objective of this study was to determine the accuracy and reliability of different groupings of markers to achieve the best accuracy and reliability for measuring scapular kinematics. Eight healthy young adult subjects were recruited. An optoelectronic marker grid was applied to the skin overlying the scapula. Two bone pins with optoelectronic marker carriers were inserted into the scapula. The accuracy of six surface marker configurations was determined by comparing the measured kinematics with scapular bone pins (the gold standard). Four humeral movements were tested: glenohumeral abduction, glenohumeral horizontal adduction, hand behind back, and forward reaching. All three rotations had a significant difference in the accuracy of the patches (p = 0.04 to p < 0.0001). For posterior tipping there was a significant effect of movement (p = 0.003) and a significant interaction (p < 0.0001). There was also a significant interaction for external rotation (p = 0.001). The marker grouping with the largest cranio-caudal spread had the highest accuracy for measuring posterior tilting (RMS 1.9°). Markers closer to the scapular spine were more accurate for tracking external rotation (RMS 2.0°) while an intermediate grouping of markers were most accurate for quantifying upward rotation (RMS 1.9°). The reliability between days ranged between 3.8° and 7.5° (based on RMS difference between trials) and there was a significant interaction between patch and movement (p < 0.0001). Intraclass correlation coefficients show moderate to good agreement for most arm movements and scapular rotations. Thus, there exists distinct optimal configurations of non-invasive marker locations for accurately measuring scapular kinematics.     

Towards the development of a novel experimental shoulder simulator with rotating scapula and individually controlled muscle forces simulating the rotator cuff

A preclinical analysis of novel implants used in shoulder surgery requires biomechanical testing conditions close to physiology. Existing shoulder experiments may only partially apply multiple cycles to simulate postoperative, repetitive loading tasks. The aim of the present study was therefore the development of an experimental shoulder simulator with rotating scapula able to perform multiple humeral movement cycles by simulating individual muscles attached to the rotator cuff. A free-hanging, metallic humerus pivoted in a polyethylene glenoid is activated by tension forces of linear electroactuators to simulate muscles of the deltoideus (DELT), supraspinatus (SSP), infraspinatus/teres minor and subscapularis. The abductors DELT and SSP apply forces with a ratio of 3:1 up to an abduction angle of 85°. The rotating scapular part driven by a rotative electro actuator provides one-third to the overall arm abduction. Resulting joint forces and moments are measured by a 6-axis load cell. A linear increase in the DELT and SSP motors is shown up to a maximum of 150 and 50 N for the DELT and SSP, respectively. The force vector in the glenoid resulted in 253 N at the maximum abduction. The present investigation shows the contribution of individual muscle forces attached to the moving humerus to perform active abduction in order to reproducibly test shoulder implants.     

不锈钢材质T形锁定板修复锁骨近端骨折及胸锁关节脱位

背景：传统的锁骨近端骨折及胸锁关节脱位内固定的修复方法包括克氏针固定、克氏针张力带钢丝固定、锁骨钩钢板及普通T形钢板内固定等,但均存在固定不牢易脱落、容易损伤神经血管及影响胸锁关节微动等不足。 目的：探讨应用不锈钢材质T形锁定板置入内固定修复锁骨近端骨折及胸锁关节脱位的疗效,观察材料与宿主的生物相容性。 方法：单县中心医院2011年3月至2014年1月收治12例锁骨近端骨折及胸锁关节脱位患者,其中锁骨近端骨折7例,胸锁关节前脱位5例,均采用切开复位T形锁定钢板内固定治疗。 结果与结论：12例患者均得到随访,随访时间3-14个月,平均9个月。所有患者切口均甲级愈合,外观无局部隆起畸形,无胸骨后重要血管及脏器损伤等不良事件发生;X射线片检查骨折均愈合,无再脱位,无内固定断裂;末次随访Rockwood评分法评定肩关节功能优良率100%。提示,不锈钢材质T形锁定板置入内固定具有固定可靠、风险小、疗效满意的特点,患者能最大程度恢复肩关节功能,是治疗锁骨近端骨折及胸锁关节脱位的有效方法。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Subject-Specific Axes of Rotation Based on Talar Morphology Do Not Improve Predictions of Tibiotalar and Subtalar Joint Kinematics

Use of subject-specific axes of rotation may improve predictions generated by kinematic models, especially for joints with complex anatomy, such as the tibiotalar and subtalar joints of the ankle. The objective of this study was twofold. First, we compared the axes of rotation between generic and subject-specific ankle models for ten control subjects. Second, we quantified the accuracy of generic and subject-specific models for predicting tibiotalar and subtalar joint motion during level walking using inverse kinematics. Here, tibiotalar and subtalar joint kinematics measured in vivo by dual-fluoroscopy served as the reference standard. The generic model was based on a cadaver study, while the subject-specific models were derived from each subject’s talus reconstructed from computed tomography images. The subject-specific and generic axes of rotation were significantly different. The average angle between the modeled axes was 12.9° ± 4.3° and 24.4° ± 5.9° at the tibiotalar and subtalar joints, respectively. However, predictions from both models did not agree well with dynamic dual-fluoroscopy data, where errors ranged from 1.0° to 8.9° and 0.6° to 7.6° for the generic and subject-specific models, respectively. Our results suggest that methods that rely on talar morphology to define subject-specific axes may be inadequate for accurately predicting tibiotalar and subtalar joint kinematics.     

Effects of Population Variability on Knee Loading During Simulated Human Gait

Cadaveric simulation models allow researchers to study native tissues in situ. However, as tests are conducted using donor specimens with unmatched kinematics, techniques that impose population average motions are subject to deviation from true physiologic conditions. This study aimed to identify factors which explain the kinetic variability observed during robotic simulations of a single human gait motion using a sample of human cadaver knees. Twelve human cadaver limbs (58 ± 16 years) were subjected to tibiofemoral geometrical analysis and cyclical stiffness testing in each anatomical degree of freedom. A simulated gait motion was then applied to each specimen. Resulting kinetics, specimen geometries, and various representations of tissue stiffness were reduced to functional attributes using principal component analysis and fit to a generalized linear prediction model. The capacity of knee topography to generate force was the largest contributor to kinetic variation in compression. Overall joint size, femoral notch height, translational laxity, and ad/abduction stiffness significantly contributed to kinetic variation in medial/lateral and anterior/posterior forces and associated torques. Future studies will investigate customizing kinematic paths to better simulate native conditions and reduce sampling variation, improving biomechanical test methods and evaluation strategies for future orthopedic techniques.     

Glenohumeral relationship in maximum elevation

Purpose

The purpose of this study was to clarify rotational relationships between the anatomical landmarks of the glenohumeral joint in maximum elevation.

Methods

Twenty-five healthy volunteers (20 men, 5 women; mean age, 31 years) held the arm in maximum elevation in an open MRI system. In each three-dimensionally computer-generated image, elevation angle of the humerus in the plane of elevation was measured, based on the glenoid and the scapular planes. Using the equator set on the head surface by the plane parallel to the humeral axis, involving the head center and the bicipital groove, glenoid location and rotational relationships were investigated.

Results

The elevation angle was 102° ± 9° in the plane 7° ± 8° anterior to the scapular plane, and axial rotation was fixed with the glenoidal long axis parallel to the equator (within 2°). Each glenoid center located on antero-superior portion of the humeral head, and the direction from the top of the head to its location was the same as that of the shaft tilting, indicating the glenoid only translated without rotation after reaching the top of the head on the equator.

Conclusions

Before reaching maximum elevation, the glenohumeral joint would be locked in axial rotation. The position when the glenoid is on the top of the humeral head with the humeral shaft perpendicular to the glenoid is considered to be essentially the final position of elevation, above which the glenohumeral joint only translates without axial rotation even if the humerus is more elevated.     

Modeling 3D object manipulation: synchronous single-axis joint rotations?

In the present paper we introduce a movement planning model that is capable of predicting object manipulation movements in three dimensions. A basic assumption of this model is that the joint kinematics of the movement are optimized, which implies that joint rotations are synchronous. Synchronous joint rotations can be considered as a simplifying strategy to control arm movements, thus controlling the timing of several segments as a whole rather than for each joint separately. We will discuss evidence for synchronous joint rotations in 2D and explain why 3D synchrony is much more complex to substantiate. Different joint-angle representations and measures of asynchrony yield conflicting results. After showing that our model predicts realistic hand paths for various movement directions (the center-out task), we focus on a task that involves re-orientation of a hand-held cylinder, thus especially zooming in on those degrees of freedom not taken into account in 2D models. The more the cylinder needs to be rotated, the more curved the hand path is. With respect to 3D synchrony, a representation of shoulder and elbow rotations as single-axis rotations comes closest to synchronous joint rotations, which suggests that the brain plans a movement in joint space as a single postural transition.     

骨质疏松患者锁骨远端骨折应用锁骨远端微孔锁定钢板与钩钢板治疗的疗效分析

目的分析骨质疏松患者锁骨远端骨折应用锁骨远端微孔锁定钢板及锁骨远端钩钢板两种内固定物治疗的临床疗效。方法回顾分析2013年1月至2016年5月于我院所收治的需要手术治疗,植入锁骨远端微孔锁定钢板或锁骨钩钢板的锁骨远端骨折的骨质疏松性患者38例,采用加州大学肩关节评分、美国肩肘外科评分以及Constant-Murley肩关节功能评分对比分析两组患者术后手术疗效。结果两组患者术前、术后一般资料无统计学差异(P>0.05),对比分析两组患者内固定前、术后3月和术后6月不同时间点的加州大学肩关节评分、美国肩周外科评分以及术后3月和术后6月的Constant-Murley肩关节功能评分,发现锁骨远端微孔锁定钢板以及锁骨远端钩钢板两种内固定治疗骨质疏松患者锁骨远端骨折,都可以获得良好的临床效果,术后患者肩关节功能均得到显著改善(P<0.05)。但是在手术治疗效果方面,术后3个月时锁骨远端微孔锁定钢板组患者肩关节功能较锁骨钩钢板组肩关节功能恢复效果更好(P<0.05),术后6个月两组间无明显差异。结论在临床上,面对骨质疏松患者锁骨远端骨折,应用锁骨远端微孔锁定钢板或锁骨钩板治疗,都可以有效重建骨质疏松患者骨折部位的稳定性,采用锁骨远端微孔锁定钢板治疗患者,术后恢复快。     

Shoulder bony landmarks location using the EOS® low-dose stereoradiography system: a reproducibility study

Purpose

To investigate the reproducibility of shoulder bony landmarks location using the EOS^® low-dose stereoradiography system, in order to validate this new tool for the study of gleno-humeral pseudo-kinematics.

Methods

An inter and intraobserver reproducibility study of shoulder bony landmarks location concerning 22 healthy volunteers. This study concerned the neutral position, arm at rest. Humerus and scapula were modeled with simple geometric shapes using specific software. Those shapes were positioned on A-P and lateral x-rays views. Images analysis of the 22 subjects was carried out three times (n _r = 3), by two observers (n _o = 2), for a total of n _tot = 132 analyses.

Results

We obtained a very good reproducibility for the humeral head center and the diaphysis axis with 95% confidence interval (IC95%) inferior to 1.09 mm and 0.41°, respectively. The uncertainty was higher for the lateral and medial epicondyles. Regarding the scapular bony landmarks, we observed a good reproducibility for the tip of the coracoid process, the inferior glenoid rim, and the axillar border with a 95% confidence interval lower than 2.13, 2.91 mm, and 3.67°, respectively. The uncertainty was higher for the most postero-lateral point of the acromion and the superior glenoid rim.

Conclusion

Our analysis of the x-rays obtained with the EOS^® low-dose stereoradiography system assessed the location reliability and reproducibility of specific scapular and humeral bony landmarks. This work opens the way to gleno-humeral pseudo-kinematics analysis using EOS^® imaging system.     

The significance of the supratrochlear aperture (STA) in elbow range of motion: an anatomical study

Assessment of the range of motion at a joint is among the methods employed by orthopedic surgeons and physiotherapists to determine courses of therapy and joint recovery. Females tend to have a greater range of motion at the elbow joint than males. In the present case–control study, the elbow extension angle was compared between males and females with and without the supratrochlear aperture. A total of 453 dry humeri and their corresponding ulnae were included in the study, and elbow extension angle was measured using a goniometer. The average extension angle in this sample was 173°, and it was significantly greater when the STA was present (\(\bar{X}\) = 175.4°) than when it was absent (\(\bar{X}\) = 171°). It was greater in females (\(\bar{X}\) = 174.5°) than in males (\(\bar{X}\) = 171.3°) irrespective of STA status, and was greater on the left in both sexes. Hyperextension characterized 13 % of the sample, whereas the majority (76 %) showed hypoextension and only a few (11 %) exhibited normal extension. Trochlear notch depth and olecranon–coronoid distance would found to be useful for predicting the presence of the supratrochlear aperture, while the transverse and vertical diameters of the supratrochlear aperture were found to be the most useful parameters when predicting the degree of extension. The functional benefits of hyperextension at the elbow joint are not fully understood. However, these results are important to orthopedic surgeons and physiotherapists as they permit a greater understanding of normal elbow range of motion in the South African population.     

Intra-protocol repeatability and inter-protocol agreement for the analysis of scapulo-humeral coordination

Multi-center clinical trials incorporating shoulder kinematics are currently uncommon. The absence of repeatability and limits of agreement (LoA) studies between different centers employing different motion analysis protocols has led to a lack dataset compatibility. Therefore, the aim of this work was to determine the repeatability and LoA between two shoulder kinematic protocols. The first one uses a scapula tracker (ST), the International Society of Biomechanics anatomical frames and an optoelectronic measurement system, and the second uses a spine tracker, the INAIL Shoulder and Elbow Outpatient protocol (ISEO) and an inertial and magnetic measurement system. First within-protocol repeatability for each approach was assessed on a group of 23 healthy subjects and compared with the literature. Then, the between-protocol agreement was evaluated. The within-protocol repeatability was similar for the ST ( $\overline{\text{RMSE}}$  = 2.35°, $\sigma_{\text{RMSE}}$  = 0.97°, SEM = 2.5°) and ISEO ( $\overline{\text{RMSE}}$  = 2.24°, $\sigma_{\text{RMSE}}$  = 0.97°, SEM = 2.3°) protocols and comparable with data from published literature. The between-protocol agreement analysis showed comparable scapula medio-lateral rotation measurements for up to 120° of flexion-extension and up to 100° of scapula plane ab-adduction. Scapula protraction–retraction measurements were in agreement for a smaller range of humeral elevation. The results of this study suggest comparable repeatability for the ST and ISEO protocols and between-protocol agreement for two scapula rotations. Different thresholds for repeatability and LoA may be adapted to suit different clinical hypotheses.     

Upper arm posture during human embryonic and fetal development

The upper extremity posture is characteristic of each Carnegie stage (CS), particularly between CS18 and CS23. Morphogenesis of the shoulder joint complex largely contributes to posture, although the exact position of the shoulder joints has not been described. In the present study, the position of the upper arm was first quantitatively measured, and the contribution of the position of the shoulder girdle, including the scapula and glenohumeral (GH) joint, was then evaluated. Twenty-nine human fetal specimens from the Kyoto Collection were used in this study. The morphogenesis and three-dimensional position of the shoulder girdle and humerus were analyzed using phase-contrast X-ray computed tomography and magnetic resonance imaging. Both abduction and flexion of the upper arm displayed a local maximum at CS20. Abduction gradually decreased until the middle fetal period, which was a prominent feature. Flexion was less than 90° at the local maximum, which was discrepant between appearance and measurement value in our study. The scapular body exhibited a unique position, being oriented internally and in the upward direction, with the glenoid cavity oriented cranially and ventrally. However, this unique scapular position had little effect on the upper arm posture because the angle of the scapula on the thorax was canceled as the angle of the GH joint had changed to a mirror image of that angle. Our present study suggested that measuring the angle of the scapula on the thorax and that of the GH joint using sonography leads to improved staging of the human embryo.     

Reliability and precision of 3D wireless measurement of scapular kinematics

To direct interventions aimed at improving scapular position and motion in shoulder pathologies, a clinically feasible, objective, sensitive and reliable assessment of scapular dyskinesis is needed. The aim of this study is to evaluate the intra- and inter-observer reliability and the precision of 3D scapula kinematics measurement using wireless sensors of an inertial and magnetic measurement system (IMMS). Scapular kinematics during humerus anteflexion and abduction of 20 subjects without shoulder pathologies were measured twice by two observers at two different days, using IMMS. Similar movement patterns and corresponding high intraclass correlation coefficients were found within (intra) and between (inter) observers, especially for scapular retraction/protraction (0.65–0.85) and medio/lateral rotation (0.56–0.91). Lowest reliability and highest difference in range of motion were observed for anterior/posterior tilt. Medio/lateral rotation and anterior/posterior tilt showed a high precision, with standard error of measurement being mostly below 5°. The inter-observer measurements of retraction/protraction showed lowest precision, reflected in systematic differences. This is caused by an offset in anatomical calibration of the sensors. IMMS enables easy and objective measurement of 3D scapula kinematics. Further research in a patient population should focus on clinical feasibility and validity for measurement of scapular dyskinesis. This would include the application of a scapula locator to enhance anatomical calibration.     

胸锁关节松动术治疗肱骨近端骨折术后患者肩关节功能障碍的效果

目的:探讨在常规治疗方案的基础上配合胸锁关节松动术对肱骨近端骨折术后肩关节功能障碍的康复疗效.方法:将40例肱骨近端骨折患者按随机数字表法分为2组,各20例.对照组采用常规治疗方案:盂肱关节松动术、超声波治疗、中药熏蒸、干扰电疗法,观察组在此基础上加入胸锁关节松动术.治疗前及治疗4周和8周后均采用Constant-Murley肩关节功能评分量表(Constant-Murley shoulder joint function assessment scale,CMS)、目测类比评分法(visual analogue score,VAS)及肩关节活动范围对患者的肩关节功能进行评定.结果:治疗4周及8周后,两组CMS总分评定显著高于治疗前,差异有统计学意义(P＜0.05).治疗4周后,观察组在日常活动(12.95±2.80)及关节活动范围(17.40±3.32)评分较对照组有显著差异,差异有统计学意义(P＜0.05).治疗8周后,观察组除疼痛评分外,在日常活动(14.70±3.79)、关节活动范围(22.10±4.38)及力量测试(15.30±2.94)评分较对照组,差异有统计学意义(P＜0.05).治疗8周后,两组在肩关节活动度及VAS评分上较治疗前均有显著提高,差异有统计学意义(P＜0.05).治疗4周后,两组肩关节前屈(108.20°±26.28°)、外展(78.35°±19.49°)及VAS评分(3.55±0.14)相比较,差异无统计学意义(P＞0.05).治疗8周后,观察组肩关节前屈(127.75°±25.30°)、外展(95.50°±16.93°)及VAS评分(2.05±0.15)明显高于对照组,差异有统计学意义(P＜0.05).结论:在常规治疗方案的基础上加用胸锁关节松动术可有效扩大肩关节活动范围,改善肩关节运动功能.     

微创电动吻合器的优化设计、功能分析与离体实验

目的开发一款新型电动吻合器,以解决现有产品转角不足、操作不便、难以掌握压榨强度等问题。方法设计一款电动吻合器并加工出样机,利用三坐标影像仪搭建样机功能测试平台测量出样机的运动轨迹曲线,用拟合优度检验来评估理论曲线与测量曲线的一致程度;在前端不同弯曲角度下,吻合新鲜离体猪小肠组织,测试吻合口的吻钉成型率。结果转弯运动与击发运动的测试曲线与理论曲线拟合优度检验理想,而压榨运动的测试曲线与理论曲线的拟合优度在转弯关节弯曲0°～30°时不理想,45°～60°时理想。性能实验中吻钉畸形率低于1.14%,表明弯曲角度对吻合效果无显著影响。结论击发运动和转弯运动的运动学测量曲线与理论曲线一致,压榨运动曲线在不同弯曲角度时存在波动,但不影响吻合效果,电动吻合器的吻合效果符合临床要求。     

Stroke-induced synergistic phase shifting and its possible implications for recovery mechanisms

Among other diminished motor capabilities, survivors of a stroke often exhibit pathological joint synergies. With respect to the upper limbs, these deficits diminish coordination in reaching, pointing, and daily task performance. Past research on pathological synergies suggests that the synergistic relationship between joints is different for flexion than in extension. One explanation for different flexion and extension synergies is that there exists a time difference between the joint being volitionally moved and the joint that moves in synergy. The goal of this research was to measure these synergistic time differences. The experiment included 11 hemiparetic subjects who performed rhythmic elbow motions at five different frequencies. A motion capture system was used to record the resulting shoulder synergies. Synergistic shoulder rotations were found to exhibit frequency-dependent phase lags (delays) and leads (advances) in the paretic arm. Furthermore, the synergistic leads and lags varied with frequency and were subject specific. We found that timing differences between joints in pathological movements are comparable to differences that were observed by other researchers for normal, able-bodied movement synergies. Moreover, the fact that pathological synergies were evident in rhythmic motion suggests that they are spinal in origin. A significant amount research exists relating to able-bodied spinal synergies. Thus, the supposition that pathological synergies are an expression of normal synergies would tie disabled movement into a larger body of work related to able-bodied synergies. The rehabilitation implications of this possible connection are discussed.     

Interpreting Musculoskeletal Models and Dynamic Simulations: Causes and Effects of Differences Between Models

With more than 29,000 OpenSim users, several musculoskeletal models with varying levels of complexity are available to study human gait. However, how different model parameters affect estimated joint and muscle function between models is not fully understood. The purpose of this study is to determine the effects of four OpenSim models (Gait2392, Lower Limb Model 2010, Full-Body OpenSim Model, and Full Body Model 2016) on gait mechanics and estimates of muscle forces and activations. Using OpenSim 3.1 and the same experimental data for all models, six young adults were scaled in each model, gait kinematics were reproduced, and static optimization estimated muscle function. Simulated measures differed between models by up to 6.5° knee range of motion, 0.012 Nm/Nm peak knee flexion moment, 0.49 peak rectus femoris activation, and 462 N peak rectus femoris force. Differences in coordinate system definitions between models altered joint kinematics, influencing joint moments. Muscle parameter and joint moment discrepancies altered muscle activations and forces. Additional model complexity yielded greater error between experimental and simulated measures; therefore, this study suggests Gait2392 is a sufficient model for studying walking in healthy young adults. Future research is needed to determine which model(s) is best for tasks with more complex motion.     

Bony structures related to snapping scapula: correlation to gender, side and age

Purpose

This study aimed at summarizing the non-pathologic bony structures which are involved in the pathogenesis of snapping scapula and evaluate their incidence, morphology and correlation to gender, side and age.

Methods

The angulation in the sagittal plane between the supraspinatus and infraspinatus portion of the medial border was measured in 140 dried scapulae. In 264 dried scapulae the medial scapular border morphology was classified into three types and the presence of the Luschka’s tubercle and the teres major tubercle or process was recorded. Correlation to gender, side and age was examined using SPSS.

Results

The mean angulation between the supraspinatus and infraspinatus portion of the medial border was 154.6° ± 8.8°. Τhe medial scapular border was straight in 99 (37.5 %), convex in 135 (51.1 %) and concave in 30 bones (11.4 %). The Luschka’s tubercle was present in eight bones (3 %), while teres major tubercle was found in 114 scapulae (43.2 %). A teres major process was present in 18 bones (6.8 %). The process was curved towards the chest wall in nine bones (3.4 %), while in the other nine scapulae (3.4 %) it had no curvature.

Conclusions

The non-pathologic bony structures which predispose to snapping scapula are not rare and include the concave medial scapular border, the Luschka’s tubercle and the teres major process curved towards the chest wall. Orthopaedic surgeons should bear in mind these non-pathologic bony structures in order not to be overlooked during the diagnostic procedure of a snapping scapula since they usually require surgical treatment.