The shape and mobility of the thoracic spine in asymptomatic adults – A systematic review of in vivo studies

A comprehensive knowledge of the thoracic shape and kinematics is essential for effective risk prevention, diagnose and proper management of thoracic disorders and assessment of treatment or rehabilitation strategies as well as for in silico and in vitro models for realistic applications of boundary conditions.After an extensive search of the existing literature, this study summarizes 45 studies on in vivo thoracic kyphosis and kinematics and creates a systematic and detailed database. The thoracic kyphosis over T1–12 determined using non-radiological devices (34°) was relatively less than measured using radiological devices (40°) during standing. The majority of kinematical measurements are based on non-radiological devices. The thoracic range of motion (RoM) was greatest during axial rotation (40°), followed by lateral bending (26°), and flexion (21°) when determined using non-radiological devices during standing. The smallest RoM was identified during extension (13°). The lower thoracic level (T8–12) contributed more to the RoM than the upper (T1–4) and middle (T4–8) levels during flexion and lateral bending. During axial rotation and extension, the middle level (T4–8) contributed the most. Coupled motion was evident, mostly during lateral bending and axial rotation. With aging, the thoracic kyphosis increased by about 3° per decade, whereas the RoM decreased by about 5° per decade for all load directions. These changes with aging mainly occurred in the lower region (T6–12). The influence of sex on thoracic kyphosis and the RoM has been described as partly contradictory. Obesity was found to decrease the thoracic RoM. Studies comparing standing, sitting and lying reported the effect of posture as significant.     

Does the examiner's experience matter in evaluation of the kinematics of the upper limb?

This study aimed to evaluate test and retest reliability according to examiner experience with the three-dimensional kinematics of the trunk, scapula, and arm segments during flexion and unilateral abduction of the arm. Ten men and 10 women (mean age, 25.1 [1.1] years) participated in this study. Each volunteer participated in six test sessions, four on the first day (two for each examiner) and two on the second day (one for each examiner). A 48-h interval was given between test days. The assessments were made by one examiner with movement analysis experience and a second examiner without experience. For each session (intra-day), the volunteers performed five repetitions of unilateral arm flexions and abductions using their dominant arms. After 1 h, the data were re-collected and all markers were replaced. Data from the trunk, scapula, and arm were analysed at 30°, 60°, 90°, and 120° of arm flexion and abduction using intraclass coefficient correlation, standard error of the measurement, and analysis of variance. The results did not differ between the experienced and inexperienced examiners except for trunk axial rotation at all studied angles and for arm rotation at 120° of abduction. The examiner previously trained in movement analysis marker placement demonstrated the same intra-tester reliability as the inexperienced tester when marker placement accuracy was the variable of interest.     

In vivo three-dimensional intervertebral kinematics of the subaxial cervical spine during seated axial rotation and lateral bending via a fluoroscopy-to-CT registration approach

Accurate measurement of the coupled intervertebral motions is helpful for understanding the etiology and diagnosis of relevant diseases, and for assessing the subsequent treatment. No study has reported the in vivo, dynamic and three-dimensional (3D) intervertebral motion of the cervical spine during active axial rotation (AR) and lateral bending (LB) in the sitting position. The current study fills the gap by measuring the coupled intervertebral motions of the subaxial cervical spine in ten asymptomatic young adults in an upright sitting position during active head LB and AR using a volumetric model-based 2D-to-3D registration method via biplane fluoroscopy. Subject-specific models of the individual vertebrae were derived from each subject’s CT data and were registered to the fluoroscopic images for determining the 3D poses of the subaxial vertebrae that were used to obtain the intervertebral kinematics. The averaged ranges of motion to one side (ROM) during AR at C3/C4, C4/C5, C5/C6, and C6/C7 were 4.2°, 4.6°, 3.0° and 1.3°, respectively. The corresponding values were 6.4°, 5.2°, 6.1° and 6.1° during LB. Intervertebral LB (ILB) played an important role in both AR and LB tasks of the cervical spine, experiencing greater ROM than intervertebral AR (IAR) (ratio of coupled motion (IAR/ILB): 0.23–0.75 in LB, 0.34–0.95 in AR). Compared to the AR task, the ranges of ILB during the LB task were significantly greater at C5/6 (p=0.008) and C6/7 (p=0.001) but the range of IAR was significantly smaller at C4/5 (p=0.02), leading to significantly smaller ratios of coupled motions at C4/5 (p=0.0013), C5/6 (p<0.001) and C6/7 (p=0.0037). The observed coupling characteristics of the intervertebral kinematics were different from those in previous studies under discrete static conditions in a supine position without weight-bearing, suggesting that the testing conditions likely affect the kinematics of the subaxial cervical spine. While C1 and C2 were not included owing to technical limitations, the current results nonetheless provide baseline data of the intervertebral motion of the subaxial cervical spine in asymptomatic young subjects under physiological conditions, which may be helpful for further investigations into spine biomechanics.     

Can self-report instruments of shoulder function capture functional differences in older adults with and without a rotator cuff tear?

Rotator cuff tears (RCT) are prevalent in older individuals and may compound age-associated functional declines. Our purpose was to determine whether self-report measures of perceived functional ability are valid for older patients with RCT. Twenty five subjects participated (12M/13F; age = 63.9 ± 3.0 years); 13 with RCT and 12 controls (CON). Participants completed self-report measures of shoulder function (SST, ASES, WORC) and health-related quality of life (SF-36). Isometric joint moment and range of motion (ROM) were measured at the shoulder. Relationships among functional self-reports, and between these measures and joint moment and ROM were assessed; group differences for total and subcategory scores were evaluated. There were significant correlations among self-reports (r_s = 0.62–0.71, p ⩽ 0.02). For RCT subjects, ASES was associated with all joint moments except adduction (p ⩽ 0.02); SST, ASES, and WORC were associated with abduction and external rotation ROM (p ⩽ 0.04). For RCT subjects, SST and WORC were associated with SF-36 physical function subcategory scores (p ⩽ 0.05). The RCT group scored worse than CON on all functional self-reports (p < 0.01) and WORC and ASES subcategories (p < 0.01). In conclusion, SST, ASES, and WORC demonstrate utility and discriminant validity for older individuals by distinguishing those with RCT, but this work suggests prioritizing ASES given its stronger association with functional group strength.     

Functional activity characteristics of individuals with shoulder dysfunctions

Shoulder-related dysfunction affects individuals’ ability to function independently and thus decreases quality of life. Functional task assessment is a key concern for a clinician in diagnostic assessment, outcome measurement, and planning of treatment programs. The purpose of this study was to test the reliability of the FASTRAK 3-dimensional (3-D) motion analysis and surface electromyography (sEMG) systems to analyze 3-D shoulder complex movements during functional tasks and compare motion patterns between subjects with and without shoulder dysfunctions (SDs).For the test, sEMG and 3-D motion analysis systems were used to characterize the functional tasks. Twenty-five asymptomatic male subjects and 21 male subjects with right shoulder disorders performed four functional tasks which involved arm reaching and raising activities with their dominant arms. Reliability was estimated by the intraclass correlation coefficient (ICC). Motion pattern was compared between two groups using mixed analysis of variances (ANOVAs). Shoulder complex kinematics and associated muscular activities during functional tasks were reliably quantified (ICC = 0.83–0.99) from the means of three trials. Relative to the group without SDs, the group with SDs showed significant alteration in shoulder complex kinematics (3°–40°) and associated muscular activities (3–10% maximum). Scapular tipping, scapular elevation, upper trapezius muscle function, and serratus anterior muscle function may have implications in the rehabilitation of patients with SDs.     

Biomechanical analysis of the anterior cervical fusion

This paper presents a biomechanical analysis of the cervical C5–C6 functional spine unit before and after the anterior cervical discectomy and fusion. The aim of this work is to study the influence of the medical procedure and its instrumentation on range of motion and stress distribution. First, a three-dimensional finite element model of the lower cervical spine is obtained from computed tomography images using a pipeline of image processing, geometric modelling and mesh generation software. Then, a finite element study of parameters' influence on motion and a stress analysis at physiological and different post-operative scenarios were made for the basic movements of the cervical spine. It was confirmed that the results were very sensitive to intervertebral disc properties. The insertion of an anterior cervical plate influenced the stress distribution at the vertebral level as well as in the bone graft. Additionally, stress values in the graft decreased when it is used together with a cage.