Technical noteThe position of the rotation center of the glenohumeral joint
Introduction
Musculoskeletal models of the upper extremity have defined the glenohumeral (GH) joint as a single rotation point (Hogfors et al., 1987; Helm et al., 1992), the position of which was based on the assumption that the rotation center equals the center of the humeral head. The position of this ‘geometric’ rotation center was specified as the center of a sphere fitted through the glenoid surface with a radius based on the size of the humeral head (Helm et al., 1989). Based on the same assumption, Meskers et al. (1998) described regression equations to the define this position relative to the anatomical landmarks on the scapula.
The position of the kinematic rotation center has, however, scarcely been measured. Poppen and Walker (1976) and Jackson et al. (1977) reported on the position of the rotation center relative to the humeral head during abduction. Their method was, however, based on a two-dimensional estimation.
The question remains whether the assumption that the geometric rotation center is also the kinematic rotation center is valid and whether this geometric rotation center can be described as the center of a sphere fitted through the glenoid surface.
To estimate the rotation center of the GH joint, an in vitro study has been performed which comprised both the estimation of the kinematic center of the intact glenohumeral joint and the geometric center of the joint, based on the shapes of both the humeral head and the glenoid. It was hypothesized that both methods would lead to identical results.
Section snippets
Method
Four fresh specimens were obtained with the approval of the Mayo Clinic internal review board. The specimens weighed between 62 and 98 kg and ranged in stature from 1.63 to 1.91 m. (Table 1). The specimens did not show visible degenerative changes in the shoulder. After anthropometric measurements, each upper extremity was disarticulated from the thorax by severing the extremity at the sternoclavicular joint and at the thoracic gliding plane. This left the arm fully intact.
A magnetic position and
Results
The measurement errors for the anatomical landmarks were typically less than 0.4 mm. The standard deviation for TS indicates differences in size between the four scapulae (Table 2).
The estimation of the kinematic rotation center was based on IHA estimations for three different movements. A typical example for these data is given in Fig. 2. Individual IHA values showed surprisingly little scatter, especially for endo-exorotation. The mean error varied from 8 mm (#1_r) to 16.5 mm (#4_r).
The rotation
Discussion
It has long since been assumed that the normal glenohumeral joint acts as a ball-and-socket joint with a fixed rotation center (Fick, 1911). Based on the assumption that kinematic behavior follows from the joint geometry, previous studies have quantified the position of the ‘geometric’ rotation center on the basis of the geometry of glenoid and humerus, relative to anatomical landmarks (Helm et al., 1989). Recently, Meskers et al. (1998) described regression equations to define this position.
Acknowledgements
This work was partially supported by a NATO Science Fellowship awarded by the Netherlands Organization for Scientific Research and NIH Grants HD07447 and AR41171.
References (13)
- et al.
Application of a magnetic tracking device to kinesiological studies
Journal of Biomechanics
(1988) - et al.
Biomechanical model of the human shoulder — I
Elements. Journal of Biomechanics
(1987) - et al.
Sequential muscular contraction
Journal of Biomechanics
(1977) - Baeyens, J. P., 1997. Three-dimensional Arthrokinematic Analysis of the Late Preparatory Phase in Handball Throwing: a...
- Fick, R., 1911. Handbuch der Anatomie und Mechanik der Gelenke, Teil III. Gustav Fischer,...
- et al.
Translation of the humeral head on the glenoid with passive glenohumeral motion
Journal of Bone & Joint Surgery — American Vol.
(1990)
Cited by (160)
A numerical study of the contact geometry and pressure distribution along the glenoid track
2022, Medical Engineering and PhysicsReverse shoulder arthroplasty with metallic augments to preserve bone and restore joint line in patients with glenoid bone loss
2022, Seminars in Arthroplasty JSESCitation Excerpt :However, in a modern RSA prosthesis, this is usually found at the surface of the baseplate. Biomechanically, the center of rotation is determined by the position and curvature of the joint line.48 In an RSA shoulder, the center of rotation is further determined by the curvature, size, and offset of the glenosphere.
Rotation sequence and marker tracking method affects the humerothoracic kinematics of manual wheelchair propulsion
2022, Journal of BiomechanicsThe effects of muscle fatigue on scapulothoracic joint position sense and neuromuscular performance
2021, Musculoskeletal Science and PracticeAn assistive upper-limb exoskeleton controlled by multi-modal interfaces for severely impaired patients: development and experimental assessment
2021, Robotics and Autonomous Systems