xiii, 79 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Subacromial impingement syndrome is the most common disorder of the shoulder. Abnormal superior translation of the humeral head is believed to be one of the major causes of this pathology. The overall purpose of this study was to better understand glenohumeral kinematics in normal healthy individuals using fluoroscopy to help comprehend the mechanism of shoulder impingement. This research was divided into three sections: a validation study to measure humeral head translation, a comparison between dynamic and static arm elevation and lastly, humeral head translation after a suprascapular nerve block. In the first study, fluoroscopy was used to take images of human cadaver shoulders. Scapular orientation was manipulated in different positions while the humerus was at 90 degrees of elevation. Humeral head translation was measured using two methods and was compared to the known translation. Additionally, the accuracy of the contour registration method to measure 2-D scapular rotations was assessed. For the second study, subjects elevated their dominant arm while fluoroscopic images were taken. An edge detection software was utilized to digitize points on both the humeral head and glenoid. Humeral head translation and scapular upward rotation were measured using a contour registration method with respect to the glenoid during arm elevation. Five different arm elevation angles were investigated to measure differences in humeral head translation between trials. There was no difference found between humeral head translation and scapular upward rotation between static and dynamic shoulder elevation. For the third study, humeral head translation was measured before and after a suprascapular never block. The humeral head was superiorly located and the scapula was more upwardly rotated after the block. The differences were observed during mid range of motion. This result showed that there was a compensatory increase in both humeral head translation and scapular upward rotation due to the nerve block. These results suggest that increasing muscular strength and endurance of the supraspinatus and infraspinatus muscle could prevent any increased superior humeral head translation. This may be beneficial in preventing shoulder impingement or rotator cuff tear over time. This dissertation includes unpublished co-authored materials. / Committee in charge: Andrew Karduna, Chairperson, Human Physiology; Li-Shan Chou, Member, Human Physiology; Louis Osternig, Member, Human Physiology; Stephen Frost, Outside Member, Anthropology

The most frequent sequelae following an obstetric brachial plexus lesion without complete functional recovery concern the impaired shoulder rotation movements and the associated structural changes of the growing glenohumeral joint. <p>This pathology is often unrecognized and may lead to a limitation in active movements, a pathologic and less efficient motion pattern in the affected limb, and the development of a severely incongruent and dysplastic glenohumeral joint prone to further arthrosis.<p><p>Hypothesis<p><p>Glenohumeral dysplasia after obstetric brachial plexus lesion has multiple etiologies: A hypothetic obstetric trauma may precede the motor imbalance, due to the initial palsy and prevalent recovery of the medial rotators of the shoulder.<p>The correction of the muscular imbalance, by neurotization of the lateral rotators (supra- and infraspinatus muscle) using a local nerve transfer or by a later muscle transfer surgery, improves function, seems to prevent the development of joint dysplasia and limits the articular deformities once they are present. <p>The early (peripartal) glenohumeral subluxation must be recognized and treated immediately to prevent the development of a severe joint contracture and dysplasia.<p> <p>Material and methods<p><p>Two retrospective and one prospective study evaluate how surgery may correct the muscular imbalance.<p>In a first series of 65 children, we analyse the recovery of the supra- and infraspinatus muscle after a nerve transfer onto the suprascapular nerve.<p>In a second retrospective analysis on 114 children, we study the outcome after secondary surgery (anterior joint release, modified Hoffer muscle transfer) dedicated to improve active and passive lateral rotation of the shoulder.<p>A prospective study of 50 magnetic resonance (MRI) scans of the glenohumeral joint describes the articular deformities.<p>Finally, 10 children presenting a very early glenohumeral subluxation have undergone a closed orthopaedic reposition and plaster immobilisation and were followed for a minimum of 2 years.<p><p>Results<p><p>In the first group, neurotization of the suprascapular nerve has been performed either by a dorsal or a ventral approach at a mean age of 14 months. The mean follow up is of 3 years and the improvement in aLR(ABD) is 68°and only 25°in aLR(ADD). None of these children with improved active lateral rotation of the shoulder developed clinical signs of a glenohumeral dysplasia within the follow up period.<p><p>Among the 114 children operated between 6 months and 44 years with a shoulder release, 74 had an isolated release procedure, 40 an associated tendon transfer or a suprascapular neurotization. The mean improvement in passive lateral rotation with the arm adducted (pLR (ADD)) was 60°. Active lateral rotation was possible in 63 % of children who underwent an isolated joint release.<p>The Hoffer muscle transfer was performed in 29 children and improved the aLR (ABD) by 60° (mean postoperative follow-up of 30 months). No signs of severe glenohumeral dysplasia developed in these children later on.<p><p>The prospective study of 50 consecutive MRI scans in children presenting at the consultation with a rotatory imbalance of their shoulder, as a sequel from obstetric brachial plexus palsy (Bahm et al. 2007) shows 37 congruent joints, 10 dorsal subluxations, 2 dorsal luxations and one complete dislocation associated with the formation of an independent neoglenoid. The humeral head was deformed in 12 cases; the glenoid in 34 children (flat in 23, biconcave 7 times, convex 3 times).<p><p>The follow up of 2 years in 10 children who underwent an immediate closed reposition shows evidence of joint congruence with a limited (30°) pLR (ADD), definitely lower than after a surgical release.<p><p>Conclusion<p><p>Some osteo-articular deformities secondary to neuromuscular diseases are well described ;those following an obstetric brachial plexus lesion are insufficiently recognized. Their etiology is unclear.<p>At the level of the shoulder joint, these sequels might be very important.<p>Our neuroorthopaedic hypothesis concerning a multifactorial etiology and treatment strategy raises the need of an early and precise screening of the deforming forces to render normal biomechanics and function.<p>The surgical strategy includes the reconstruction of the responsible motor nerve and the improvement of the passive and active range of motion of the shoulder in lateral rotation<p>It seems to be efficient to limit the progression to severe glenohumeral dysplasia and further arthrosis.<p> / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished