Effect of Plane of Arm Elevation on Glenohumeral Kinematics A Normative Biplane Fluoroscopy Study
ABSTRACT Background: Understanding glenohumeral motion in normal and pathologic states requires the precise measurement of shoulder kinematics. The effect of the plane of arm elevation on glenohumeral translations and rotations remains largely unknown. The purpose of this study was to measure the three-dimensional glenohumeral translations and rotations during arm elevation in healthy subjects. Methods: Eight male subjects performed scaption and forward flexion, and five subjects (three men and two women) performed abduction, inside a dynamic biplane fluoroscopy system. Bone geometries were extracted from computed tomography images and used to determine the three-dimensional position and orientation of the humerus and scapula in individual frames. Descriptive statistics were determined for glenohumeral joint rotations and translations, and linear regressions were performed to calculate the scapulohumeral rhythm ratio. Results: The scapulohumeral rhythm ratio was 2.0 +/- 0.4:1 for abduction, 1.6 +/- 0.5:1 for scaption, and 1.1 +/- 0.3:1 for forward flexion, with the ratio for forward flexion being significantly lower than that for abduction (p = 0.002). Humeral head excursion was largest in abduction (5.1 +/- 1.1 mm) and smallest in scaption (2.4 +/- 0.6 mm) (p < 0.001). The direction of translation, as determined by the linear regression slope, was more inferior during abduction (-2.1 +/- 1.8 mm/90 degrees) compared with forward flexion (0.1 +/- 10.9 mm/90 degrees) (p = 0.024). Conclusions: Scapulohumeral rhythm significantly decreased as the plane of arm elevation moved in an anterior arc from abduction to forward flexion. The amount of physiologic glenohumeral excursion varied significantly with the plane of elevation, Was smallest for scaption, and showed inconsistent patterns across subjects with the exception of consistent inferior translation during abduction.
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ABSTRACT: Background Glenohumeral displacements assessment would help to design shoulder prostheses with physiological arthrokinematics and to establish more biofidelic musculoskeletal models. Though displacements were documented during static tasks, there is little information on their 3D coupling with glenohumeral angle during dynamic tasks. Our objective was to characterize the 3D glenohumeral displacements-rotations couplings during dynamic arm elevations and rotations. Methods Glenohumeral displacements were measured from trajectories of reflective markers fitted on intracortical pins inserted into the scapula and humerus. Bone geometry was recorded using CT-scan. Only four participants were recruited to the experiment due to its invasiveness. Participants performed dynamic arm abduction, flexion and axial rotations. Linear regressions were performed between glenohumeral displacements and rotations. The pin of the scapula of one participant moved, his data were removed from analysis, and results are based on three participants. Findings The measurement error of glenohumeral kinematics was less than 0.15 mm and 0.2°. Maximum glenohumeral displacements were measured along the longitudinal direction and reached up to + 12.4 mm for one participant. Significant couplings were reported especially between longitudinal displacement and rotation in abduction (adjusted R2 up to 0.94). Interpretation The proposed method provides the potential to investigate glenohumeral kinematics during all kind of movements. A linear increase of upward displacement during dynamic arm elevation was measured, which contrasts with results based on series of static poses. The systematic investigation of glenohumeral displacements under dynamic condition may help to provide relevant recommendation for design of shoulder prosthetic components and musculoskeletal models.Clinical Biomechanics 08/2014; 29(9). DOI:10.1016/j.clinbiomech.2014.08.006 · 1.88 Impact Factor
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ABSTRACT: Computer-assisted imaging analysis technology has been widely used in the musculoskeletal joint biomechanics research in recent years. Imaging techniques can accurately reconstruct the anatomic features of the target joint and reproduce its in vivo motion characters. The data has greatly improved our understanding of normal joint function, joint injury mechanism, and surgical treatment, and can provide foundations for using reverse-engineering methods to develop biomimetic artificial joints. In this paper, we systematically reviewed the investigation of in vivo kinematics of the human knee, shoulder, lumber spine, and ankle using advanced imaging technologies, especially those using a dual fluoroscopic imaging system (DFIS). We also briefly discuss future development of imaging analysis technology in musculoskeletal joint research.01/2014; 2(1). DOI:10.1016/j.jot.2013.11.001
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ABSTRACT: Study Design Cross-sectional. Objectives To compare differences in glenohumeral joint angular motion and linear translations between symptomatic and asymptomatic individuals during shoulder motion performed in 3 planes of humerothoracic elevation. Background Numerous clinical theories have linked abnormal glenohumeral kinematics including decreased glenohumeral external rotation and increased superior translation to individuals with shoulder pain and impingement diagnoses. However, relatively few studies have investigated glenohumeral joint angular motion and linear translations in this population. Methods Transcortical bone pins were inserted into the scapula and humerus of 12 asymptomatic and 10 symptomatic participants for direct bone-fixed tracking using electromagnetic sensors. Glenohumeral joint angular positions and linear translations were calculated during active shoulder flexion, abduction, and scapular plane abduction. Results Differences between groups in angular positions were limited to glenohumeral elevation coinciding with a reduction in scapulothoracic upward rotation. Symptomatic participants demonstrated 1.4 mm more anterior glenohumeral translation between 90 and 120° shoulder flexion and an average of 1 mm more inferior glenohumeral translation throughout shoulder abduction. Conclusion Differences in glenohumeral kinematics exist between symptomatic and asymptomatic individuals. The clinical implications of these differences are not yet understood and more research is needed to understand the relationship between abnormal kinematics, shoulder pain, and pathoanatomy. J Orthop Sports Phys Ther, Epub 7 August 2014. doi:10.2519/jospt.2014.5556.Journal of Orthopaedic and Sports Physical Therapy 08/2014; 44(9):1-42. DOI:10.2519/jospt.2014.5556 · 2.38 Impact Factor