Biomedical subjects

K Thren

Publications and source records attributed to K Thren.

4 recordsLinked to original sources

PubMed1995

[Dynamic stability of the glenohumeral joint. A biomechanical study].

Stability of the glenohumeral joint with an anterior, posterior and inferior displacement force of 50 Newton was measured in a dynamic shoulder model. Controlled hydrodynamic actuator forces were applied to the deltoid muscle and to the rotator cuff in seven anatomic specimens. During elevation of the arm, the position of the humerus was measured with a six-degree-of-freedom ultrasonic sensor device. The rotational center of the humeral head was used as reference point for translation. A displacement force of 50N led to significant humeral head displacement anteriorly and posteriorly, but not inferiorly. A 50% reduction of rotator cuff forces increased anterior displacement by 46% and posterior displacement by 31%. Venting of the glenohumeral joint space and of the subacromial bursa resulted in a 50% increase of anterior displacement, a 19% increase of posterior displacement and in significant inferior displacement. This study demonstrates that, in addition to passive stabilizers and negative intraarticular pressure, rotator cuff force significantly contributes to stabilization of the glenohumeral joint during arm motion. Muscle strength and coordination should gain more emphasis in the diagnosis and treatment of shoulder instability.

Adult↗

PubMed1994

Translation of the glenohumeral joint with simulated active elevation.

Translation of the glenohumeral joint was measured with a dynamic shoulder model during elevation of the arm in 8 cadaveric specimens. Controlled hydrodynamic actuator forces were applied to the deltoid muscle and the rotator cuff through wire cables. Using a constant force ratio, the glenohumeral joint was elevated to 90 degrees. The position of the arm in all spatial orientations was measured with an ultrasonic device. Reproducibility of glenohumeral joint motion was demonstrated on the basis of 5 cycles of glenohumeral joint elevation. The rotational center of the humeral head was used as the reference point for translation. Translation during elevation of the glenohumeral joint between 20 degrees and 90 degrees averaged 9.0 mm +/- 5.2 mm superiorly and 4.4 mm +/- 1.3 mm anteriorly. Physiologic variation of muscle activity, which is not yet fully understood, was not included in the model. In vivo, translation may be diminished by coordinated activity of the rotator cuff. The presence of significant glenohumeral joint translation underlines the importance of active, muscular guidance at the shoulder. Physiologic translation must be considered in the design of total shoulder arthroplasty, in shoulder instability, and in the impingement syndrome.

Adult↗

PubMedDate not supplied

Dynamic glenohumeral joint stability.

Stability of the glenohumeral joint with an anterior, posterior, and inferior displacement force of 50 N was measured in a dynamic shoulder model. Controlled hydrodynamic actuator forces were applied to the deltoid muscle and to the rotator cuff in seven anatomic specimens. During elevation of the arm the position of the humerus was measured with a six-degree-of-freedom ultrasonic sensor device. The rotational center of the humeral head was used as a reference point for translation. A displacement force of 50 N led to significant humeral head displacement anteriorly and posteriorly but not inferiorly. A 50% reduction of rotator cuff forces increased anterior displacement by 46% and posterior displacement by 31%. Venting of the glenohumeral joint space and of the subacromial bursa resulted in a 50% increase of anterior displacement, a 19% increase of posterior displacement, and significant inferior displacement. This study demonstrates that in addition to passive stabilizers and negative intraarticular pressure, rotator cuff force significantly contributes to stabilization of the glenohumeral joint during arm motion. Muscle strength and coordination should gain more emphasis in the diagnosis and treatment of shoulder instability.

Adult↗

PubMedDate not supplied

[Measurement of glenohumeral joint translation with a dynamic shoulder model].

Translation of the glenohumeral joint was measured with a dynamic shoulder model, during elevation of the arm in eight cadaveric specimens. Controlled hydrodynamic actuator forces were applied to the deltoid muscle and the rotator cuff through wire cables. Using a constant force ratio, the glenohumeral joint was elevated to 90 degrees. The position of the arm in all spatial orientations was measured with an ultrasonic device. Reproducibility of glenohumeral joint motion was demonstrated on the basis of five cycles of glenohumeral joint elevation. The rotational center of the humeral head was used as the reference point for translation. Translation during elevation of the glenohumeral joint between 20 degrees and 90 degrees averaged 9.0 mm +/- 5.2 mm superiorly and 4.4 mm +/- 1.3 mm anteriorly. In vivo, this may be diminished by coordinated activity of the rotator cuff. The presence of significant glenohumeral joint translation underlines the importance of active, muscular guidance at the shoulder. Physiologic translation of total shoulder arthroplasty, in shoulder instability and in the impingement syndrome.

Adult↗