Change in the Distance From the Axillary Nerve to the Glenohumeral Joint With Shoulder External Rotation or Abduction Position

Background: This study investigated whether axillary nerve (AN) distance to the inferior border of the humeral head and inferior glenoid would change while placing the glenohumeral joint in different degrees of external rotation and abduction. Methods: A standard deltopectoral approach was performed on 10 fresh-frozen cadaveric specimens. The distance between AN and the inferior border of the humeral head and inferior glenoid while placing the shoulder in 0°, 45°, and 90° of external rotation or abduction was measured. Continuous variables for changes in AN position were compared with paired 2-tailed Student t test. Results: The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of external rotation and 0° of abduction was 13.77 mm (SD 4.31), 13.99 mm (SD 4.12), and 16.28 mm (SD 5.40), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of external rotation was 16.33 mm (SD 3.60), 15.60 mm (SD 4.19), and 16.43 (SD 5.35), respectively. The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of abduction and 0° of external rotation was 13.76 mm (SD 4.31), 10.68 mm (SD 4.19), and 3.81 mm (SD 3.08), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of abduction was 16.33 mm (SD 3.60), 17.66 mm (SD 5.80), and 12.44 mm (SD 5.57), respectively. Conclusions: The AN position relative to the inferior aspect of the glenohumeral joint does not significantly change despite position of external rotation. Increasing shoulder abduction over 45° decreases the distance from the glenohumeral joint to the AN and should be avoided.

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Effect of Posterior Capsule Tightness on Glenohumeral Translation in the Late-Cocking Phase of Pitching

Journal of Sport Rehabilitation ◽

10.1123/jsr.16.1.41 ◽

2007 ◽

Vol 16 (1) ◽

pp. 41-49 ◽

Cited By ~ 35

Author(s):

Kim M. Clabbers ◽

John D. Kelly ◽

Dov Bader ◽

Matthew Eager ◽

Carl Imhauser ◽

...

Keyword(s):

Outcome Measures ◽

Humeral Head ◽

Glenohumeral Joint ◽

External Rotation ◽

Head Position ◽

Posterior Capsule ◽

Nonsignificant Trend ◽

Before And After ◽

Fresh Frozen ◽

Head Translation

Context:Throwing injuries.Objective:To study the effects of posterior capsule tightness on humeral head position in late cocking simulation.Design:Eight fresh frozen shoulders were placed in position of “late cocking,” 90 degrees abduction, and 10 degrees adduction and maximal external rotation. 3D measurements of humeral head relationship to the glenoid were taken with an infrared motion sensor, both before and after suture plication of the posterior capsule. Plications of 20% posterior/inferior capsule and 20% entire posterior capsule were performed, followed by plications of 40% of the posterior/inferior capsule and 40% entire posterior capsule.Setting:Cadaver Lab.Intervention:Posterior capsular placation.Main Outcome Measures:Humeral head position.Results:40%, but not 20%, posterior/inferior and posterior plications demonstrated a trend to increased posterior-superior humeral head translation relative to controls.Conclusion:Surgically created posterior capsular tightness of the glenohumeral joint demonstrated a nonsignificant trend to increased posterior/superior humeral head translation in the late cocking position of throwing.

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Biomechanical Evaluation of Glenoid Reconstruction With an Implant-Free J-Bone Graft for Anterior Glenoid Bone Loss

The American Journal of Sports Medicine ◽

10.1177/0363546517716927 ◽

2017 ◽

Vol 45 (12) ◽

pp. 2849-2857 ◽

Cited By ~ 13

Author(s):

Leo Pauzenberger ◽

Felix Dyrna ◽

Elifho Obopilwe ◽

Philipp R. Heuberer ◽

Robert A. Arciero ◽

...

Keyword(s):

Bone Graft ◽

Bone Grafting ◽

Humeral Head ◽

External Rotation ◽

Glenoid Defect ◽

Contact Patterns ◽

Grafting Technique ◽

The Mean ◽

The Creation ◽

Glenoid Reconstruction

Background: The anatomic restoration of glenoid morphology with an implant-free J-shaped iliac crest bone graft offers an alternative to currently widely used glenoid reconstruction techniques. No biomechanical data on the J-bone grafting technique are currently available. Purpose: To evaluate (1) glenohumeral contact patterns, (2) graft fixation under cyclic loading, and (3) the initial stabilizing effect of anatomic glenoid reconstruction with the implant-free J-bone grafting technique. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric shoulders and J-shaped iliac crest bone grafts were used for this study. J-bone grafts were harvested, prepared, and implanted according to a previously described, clinically used technique. Glenohumeral contact patterns were measured using dynamic pressure-sensitive sensors under a compressive load of 440 N with the humerus in (a) 30° of abduction, (b) 30° of abduction and 60° of external rotation, (c) 60° of abduction, and (d) 60° of abduction and 60° of external rotation. Using a custom shoulder-testing system allowing positioning with 6 degrees of freedom, a compressive load of 50 N was applied, and the peak force needed to translate the humeral head 10 mm anteriorly at a rate of 2.0 mm/s was recorded. All tests were performed (1) for the intact glenoid, (2) after the creation of a 30% anterior osseous glenoid defect parallel to the longitudinal axis of the glenoid, and (3) after anatomic glenoid reconstruction with an implant-free J-bone graft. Furthermore, after glenoid reconstruction, each specimen was translated anteriorly for 5 mm at a rate of 4.0 mm/s for a total of 3000 cycles while logging graft protrusion and mediolateral bending motions. Graft micromovements were recorded using 2 high-resolution, linear differential variable reluctance transducer strain gauges placed in line with the long leg of the graft and the mediolateral direction, respectively. Results: The creation of a 30% glenoid defect significantly decreased glenohumeral contact areas ( P < .05) but significantly increased contact pressures at all abduction and rotation positions ( P < .05). Glenoid reconstruction restored the contact area and contact pressure back to levels of the native glenohumeral joint in all tested positions. The mean (±SD) force to translate the humeral head anteriorly for 10 mm (60° of abduction: 31.7 ± 12.6 N; 60° of abduction and 60° of external rotation: 28.6 ± 7.6 N) was significantly reduced after the creation of a 30% anterior bone glenoid defect (60° of abduction: 12.2 ± 6.8 N; 60° of abduction and 60° of external rotation: 11.4 ± 5.4 N; P < .001). After glenoid reconstruction with a J-bone graft, the mean peak translational force significantly increased (60° of abduction: 85.0 ± 8.2 N; 60° of abduction and 60° of external rotation: 73.6 ± 4.5 N; P < .001) compared with the defect state and baseline. The mean total graft protrusion under cyclical translation of the humeral head over 3000 cycles was 138.3 ± 169.8 µm, whereas the mean maximal mediolateral graft deflection was 320.1 ± 475.7 µm. Conclusion: Implant-free anatomic glenoid reconstruction with the J-bone grafting technique restored near-native glenohumeral contact areas and pressures, provided secure initial graft fixation, and demonstrated excellent osseous glenohumeral stability at time zero. Clinical Relevance: The implant-free J-bone graft is a viable alternative to commonly used glenoid reconstruction techniques, providing excellent graft fixation and glenohumeral stability immediately postoperatively. The normalization of glenohumeral contact patterns after reconstruction could potentially avoid the progression of dislocation arthropathy.

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Digital analysis of external fixation area of proximal humerus fractures in elderly patients

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04826-0 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Baorui Xing ◽

Yadi Zhang ◽

Xiuxiu Hou ◽

Yunmei Li ◽

Guoliang Li ◽

...

Keyword(s):

Humeral Head ◽

3D Model ◽

Proximal Humerus ◽

Sagittal Plane ◽

Axillary Nerve ◽

Coronal Plane ◽

Inferior Surface ◽

Vertical Distance ◽

Inferior Border ◽

Superior Border

Abstract Introduction The purpose is based on anatomical basis, combined with three-dimensional measurement, to guide the clinical repositioning of proximal humeral fractures, select the appropriate pin entry point and angle, and simulate surgery. Methods 11 fresh cadaveric specimens were collected, the distance of the marked points around the shoulder joint was measured anatomically, and the vertical distance between the inferior border of the acromion and the superior border of the axillary nerve, the vertical distance between the apex of the humeral head and the superior border of the axillary nerve, the vertical distance between the inferior border of the acromion and the superior border of the anterior rotator humeral artery, and the vertical distance between the apex of the humeral head and the superior border of the anterior rotator humeral artery were marked on the 3D model based on the anatomical data to find the relative safety zone for pin placement. Results Contralateral data can be used to guide the repositioning and fixation of that side of the proximal humerus fracture, and uniform data cannot be used between male and female patients. For lateral pining, the distance of the inferior border of the acromion from the axillary nerve (5.90 ± 0.43) cm, range (5.3-6.9) cm, was selected for pining along the medial axis of the humeral head, close to the medial cervical cortex, and the pining angle was measured in the coronal plane (42.84 ± 2.45)°, range (37.02° ~ 46.31°), and in the sagittal plane (28.24 ± 2.25)°, range (19.22° ~ 28.51°). The pin was advanced laterally in front of the same level of the lateral approach point to form a cross-fixed support with the lateral pin, and the pin angle was measured in the coronal plane (36.14 ± 1.75)°, range (30.32° ~ 39.61°), and in the sagittal plane (28.64 ± 1.37)°, range (22.82° ~ 32.11°). Two pins were taken at the greater humeral tuberosity for fixation, with the proximal pin at an angle (159.26 ± 1.98) to the coronal surface of the humeral stem, range (155.79° ~ 165.08°), and the sagittal angle (161.76 ± 2.15)°, with the pin end between the superior surface of the humeral talus and the inferior surface of the humeral talus. The distal needle of the greater humeral tuberosity was parallel to the proximal approach trajectory, and the needle end was on the inferior surface of the humeral talus. Conclusion Based on the anatomical data, we can accurately identify the corresponding bony structures of the proximal humerus and mark the location of the pin on the 3D model for pin placement, which is simple and practical to meet the relevant individual parameters.

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Anatomy and Biomechanic of the Shoulder

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967119s00466 ◽

2019 ◽

Vol 7 (11_suppl6) ◽

pp. 2325967119S0046

Author(s):

Troydimas Panjaitan

Keyword(s):

Rotator Cuff ◽

Humeral Head ◽

Glenohumeral Joint ◽

External Rotation ◽

Central Component ◽

Subscapularis Tendon ◽

Glenoid Fossa ◽

Greater Tuberosity ◽

Glenohumeral Ligaments ◽

Shoulder Complex

The shoulder is one of the most complex joints of the human body. Consequently, they are susceptible to injury and degeneration. Mechanical shoulder pathology typically results when overuse, extremes of motion, or excessive forces overwhelm intrinsic material properties of the shoulder complex resulting in tears of the rotator cuff, capsule, and labrum. The fundamental central component of the shoulder complex is the glenohumeral joint. It has a ball-and-socket configuration with a surface area ratio of the humeral head to glenoid fossa of about 3:1 with an appearance similar to a golf ball on a tee. Overall, there is minimal bony covering and limited contact areas that allow extensive translational and rotational ability in all three planes. The glenohumeral joint has 2 groups of stabilizers, which are static (passive) and dynamic (active) restrains. Static stabilizers include the concavity of the glenoid fossa, glenoid fossa retroversion and superior angulation, glenoid labrum, the joint capsule, and glenohumeral ligaments, and a vacuum effect from negative intra-articular pressure. Dynamic stabilization is merely the coordinated contraction of the rotator cuff muscles that create forces that compress the articular surfaces of the humeral head into the concave surface of the glenoid fossa. During upper extremity movement, the effects of static stabilizers are minimized and dynamic or active stabilizers become the dominant forces responsible for glenohumeral stability The simple act of arm elevation is a complex task that occurs via the combination of glenohumeral and scapulothoracic motion, together known as scapulohumeral rhythm. In the first 1200, glenohumeral arm abduction, the supraspinatus and deltoid work together and create a force couple that promotes stability, while raising the arm (deltoid contraction). In addition, the humerus must undergo 450 external rotation to not only clear the greater tuberosity posteriorly but also loosen the inferior glenohumeral ligament (IGHL) to allow maximum elevation. There are several anatomical updates regarding the rotator cuff and capsular footprint. The footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed, and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus. The superior-most insertion of the subscapularis tendon extends a thin tendinous slip, which attaches to the fovea capitis of the humerus. The teres minor muscle inserts to the lowest impression of the greater tuberosity of the humerus and additionally inserts to the posterior side of the surgical neck of the humerus.

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Imaging assessment of glenohumeral dysplasia secondary to brachial plexus birth palsy

Radiologia Brasileira ◽

10.1590/0100-3984.2015.0039 ◽

2016 ◽

Vol 49 (3) ◽

pp. 144-149 ◽

Cited By ~ 8

Author(s):

Francisco Abaete Chagas-Neto ◽

Vitor Faeda Dalto ◽

Michel Daoud Crema ◽

Peter M. Waters ◽

Everaldo Gregio-Junior ◽

...

Keyword(s):

Brachial Plexus ◽

Humeral Head ◽

Glenohumeral Joint ◽

Glenoid Version ◽

Cross Sectional ◽

Posterior Displacement ◽

Brachial Plexus Birth Palsy ◽

Glenohumeral Dysplasia ◽

The Mean ◽

Birth Palsy

Abstract Objective: To assess imaging parameters related to the morphology of the glenohumeral joint in children with unilateral brachial plexus birth palsy (BPBP), in comparison with those obtained for healthy shoulders. Materials and Methods: We conducted a retrospective search for cases of unilateral BPBP diagnosed at our facility. Only patients with a clinical diagnosis of unilateral BPBP were included, and the final study sample consisted of 10 consecutive patients who were assessed with cross-sectional imaging. The glenoid version, the translation of the humeral head, and the degrees of glenohumeral dysplasia were assessed. Results: The mean diameter of the affected humeral heads was 1.93 cm, compared with 2.33 cm for those of the normal limbs. In two cases, there was no significant posterior displacement of the humeral head, five cases showed posterior subluxation of the humeral head, and the remaining three cases showed total luxation of the humeral head. The mean glenoid version angle of the affected limbs (90-α) was -9.6º, versus +1.6º for the normal, contralateral limbs. Conclusion: The main deformities found in this study were BPBP-associated retroversion of the glenoid cavity, developmental delay of the humeral head, and posterior translation of the humeral head.

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Recurrent Anterior Glenohumeral Instability-Arthroscopic Results of Bankart Repair

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967114s00268 ◽

2014 ◽

Vol 2 (11_suppl3) ◽

pp. 2325967114S0026

Author(s):

Ahmet Guney ◽

İbrahim Karaman ◽

Murat Kahraman ◽

Mithat Öner ◽

Erdal Uzun ◽

...

Keyword(s):

Open Surgery ◽

External Rotation ◽

Arthroscopic Repair ◽

Daily Activities ◽

Bankart Repair ◽

Shoulder Abduction ◽

Arthroscopic Bankart Repair ◽

The Mean ◽

The Difference

Objectives: In the treatment of traumatic anterior shoulder instability there is still not formed a ideal consensus. Although the results of the open technique for repairing Bankart lesions detected in these patients, in recent years with the development of arthroscopic methods, arthroscopic Bankart repair with the successful results are obtained. We aimed to present our results of Bankart repair with the arthroscopic method. Methods: The study included 42 patients who underwent arthroscopic Bankart repair in our clinic between the years 2011-2014. Mean age was 26.3 (18-37). Preoperative and postoperative pain and functions of the patients were assessed using the Constant and Rowe scores. The mean follow-up period was 19 months (range 6 to 30 months). Patients with at least two dislocations were included in the study. The mean number of dislocations was 4.8 (2-10). The mean time from the first trauma to surgical intervention was 2.5 years (range 0.5 to 10 years). Patients with multidirectional instability were excluded. Repair was performed using double-stranded double with the standard anterior portal. Decision for surgical treatment was made based on limitation of activities because of fear of having a dislocation and on positive results of instability tests. Before surgery for all patients, a detailed clinical examination, conventional radiography and conventional MRI were evaluated. All the patients had labral tears on preoperative magnetic resonance scans and had complaints of instability even during daily activities. Results: The mean passive shoulder abduction was 155 (145-170) degrees and mean external rotation was measured 80 (60-90) degrees. The mean preoperative Rowe score was 42 points, while the postoperative score was 89.1 points at the last time follow up. The difference was statistically significant (p <0.05). The Constant score was 52 preoperatively and increased to 85 points after the surgery. The difference was statistically significant (p <0.05). The mean loss of external rotation was observed %28.75 and the last time follow up decreased to %8.2. The difference was statistically significant (p <0.05). All of the patients returned to their daily activities and no dislocation has been occurred. Conclusion: Although, in the past, the results of arthroscopic repair were less satisfactory compared to open and mini open surgery. This condition has changed remarkably. The results of arthroscopic repair in our study were good enough compared to open surgeries. Also in patients who underwent arthroscopic repair, length of hospital stay is shorter, less pain and less scar tissue occurs after the surgery. We believe that, with enhanced experience and advances in arthroscopic repair techniques, arthroscopic treatment may outweigh open surgery.

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Mid-Term outcomes following fresh-frozen humeral head osteochondral allograft reconstruction for reverse Hill Sachs lesion: a case series

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04657-z ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Giulio Maria Marcheggiani Muccioli ◽

Vito Gaetano Rinaldi ◽

Giada Lullini ◽

Alice Ritali ◽

Massimiliano Mosca ◽

...

Keyword(s):

Humeral Head ◽

Shoulder Dislocation ◽

Case Series ◽

Posterior Shoulder Dislocation ◽

Link Type ◽

Locked Posterior Shoulder Dislocation ◽

Posterior Shoulder ◽

Fresh Frozen ◽

The Mean ◽

Osteochondral Allografts

Abstract Background Locked posterior glenohumeral dislocations with a reverse Hill-Sachs impaction fracture involving less than 30% of the humeral head are most frequently treated with lesser tuberosity transfer into the defect, whereas those involving more than 50% undergo humeral head arthroplasty. Reconstruction of the defect with segmental femoral osteochondral allografts has been proposed to treat patients between these two ranges, but the medium−/long-term outcomes of this joint-preserving procedure are controversial. Methods Between 2001 and 2018, 12 consecutive patients with a unilateral locked posterior shoulder dislocation and an impaction fracture from 30 to 50% (mean 31% ± 1.32) of the humeral head were treated with segmental reconstruction of the defect with fresh-frozen humeral head osteochondral allografts. Patients were assessed clinically, radiographically and with computed tomography (CT) at a medium follow-up of 66 ± 50.25 months (range, 24–225). Results All twelve shoulders presented a slight limitation in anterior elevation (average, 166.6° ± 22.76). The mean active external rotation with the shoulder at 90° of abduction was 82.5° ± 6.61, and that with the arm held in stable adduction was 79.16 ± 18.80. The mean abduction was 156.25° ± 25.09. The mean Constant-Murley score (CS) was 82 ± 15.09 points (range, 40–97 points), and the mean ASES was 94 ± 8.49 points. The mean pre- and postoperatively Western Ontario Shoulder Instability index (WOSI) was 236.5 ± 227.9 and 11.20 ± 10.85, respectively. Development of osteoarthrosis (OA) was minimal. The average allograft resorption rate was 4% ± 2.4. There were no cases of failure (reoperation for any reason) in this series. Conclusion Segmental humeral head reconstruction with humeral head fresh-frozen osteochondral allografts provides good to excellent clinical results with low-grade OA and low allograft resorption in patients with locked posterior shoulder dislocation. Trial registration ClinicalTrials.gov PRS, ClinicalTrials.gov ID: NCT04823455. Registered 29 March 2021 - Retrospectively registered, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S000AU8P&selectaction=Edit&uid=U0004J36&ts=12&cx=6cykp8 Level of evidence Level IV, Case Series, Treatment Study.

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Four-Dimensional Computed Tomography Evaluation of Shoulder Joint Motion in Collegiate Baseball Pitchers

10.21203/rs.3.rs-648232/v1 ◽

2021 ◽

Author(s):

Daisuke Momma ◽

Alejandro A Espinoza Orías ◽

Tohru Irie ◽

Tomoyo Irie ◽

Eiji Kondo ◽

...

Keyword(s):

Computed Tomography ◽

Internal Rotation ◽

Contact Area ◽

Humeral Head ◽

Glenohumeral Joint ◽

External Rotation ◽

Ct Scanning ◽

4D Ct ◽

Collegiate Baseball ◽

Baseball Pitchers

Abstract The purpose of this study is to evaluate the glenohumeral contact area, center of glenohumeral contact area, and center of humeral head during simulated pitching motion in collegiate baseball pitchers using four-dimensional computed tomography (4D CT). We obtained 4D CT data from the dominant and non-dominant shoulders of eight collegiate baseball pitchers during the cocking motion. CT image data of each joint were reconstructed using a 3D reconstruction software package. The glenohumeral contact area, center of glenohumeral contact area, center of humeral head, and oblateness of humeral head were calculated from 3D bone models using customized software. The center of glenohumeral contact area translated significantly from anterior to posterior during maximum external rotation to maximum internal rotation. The center of humeral head translated from posterior to anterior during maximum external rotation to maximum internal rotation. There was a high negative correlation between anterior translation of the center of glenohumeral contact area and center of humeral head, and a positive correlation between the translation and the oblateness. 4D CT analyses demonstrated that the center of humeral head translated in the opposite direction to that of the center of glenohumeral contact area during external rotation to internal rotation in abduction in the dominant and non-dominant shoulders. This diametric translation can be explained by the oblateness of the humeral head. 4D CT scanning and the software for bone surface modeling of the glenohumeral joint enabled quantitative assessment of glenohumeral micromotion and identified humeral head oblateness as the cause of diametric change.

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Cadaveric Dissection of the Axillary Nerve: An Investigation of Extra-Muscular and Intra-Muscular Branching Patterns

The Journal of Hand Surgery (Asian-Pacific Volume) ◽

10.1142/s2424835518500546 ◽

2018 ◽

Vol 23 (04) ◽

pp. 533-538 ◽

Cited By ~ 2

Author(s):

Pratik Rastogi ◽

David A. Stewart ◽

Richard D. Lawson ◽

Dominique M. Tremblay ◽

Belinda J. Smith ◽

...

Keyword(s):

Deltoid Muscle ◽

Axillary Nerve ◽

Common Trunk ◽

Nerve Injuries ◽

Branching Patterns ◽

Fresh Frozen ◽

The Mean ◽

Posterior Division ◽

Anterior Division ◽

Teres Minor

Background: Variations in the axillary nerve branching patterns have been reported. The aim of the study is to investigate the extra- and intra-muscular course of the axillary nerve and quantify the regional innervation of the deltoid. Methods: In fresh frozen specimens, the origin of the axillary nerve from the posterior cord of the brachial plexus and its extra- and intra-muscular course were identified. Muscle dimensions, branching patterns and the distance from the axillary nerve origin to major branches were measured. The weights of muscle segments supplied by major branches of the axillary nerve were recorded. Results: Twenty-three cadaveric dissections were completed. The axillary nerve bifurcated within the quadrangular space in all cases. The mean distance from the origin to bifurcation of the axillary nerve was 39 ± 13 mm; from axillary nerve bifurcation to the teres minor branch was 13 ± 6 mm; and from axillary nerve bifurcation to the middle branch of anterior division was 26 ± 11 mm. The nerve to teres minor and superior lateral brachial cutaneous nerve originated from the posterior division or common trunk in all cases. No fibrous raphe were identified separating anterior, middle and posterior deltoid segments. The anterior division of axillary nerve supplied 85 ± 4% of the deltoid muscle (by weight). The posterior division supplied 15 ± 4% of the deltoid muscle (by weight). The posterior deltoid was supplied by both anterior and posterior divisions in 91.3% of cases. Conclusions: This study demonstrates a consistent branching pattern of the axillary nerve. The anterior division of the axillary nerve innervates all three deltoid segments in most instances (85% of the deltoid by weight). This study supports the concept of re-innervation of the anterior division alone in isolated axillary nerve injuries.

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Simulator Based Experimental Motion Analysis of 3D Printed Artificial Shoulder Joint Geometries

10.29007/4vgs ◽

2018 ◽

Author(s):

Nad Siroros ◽

Mark Verjans ◽

Klaus Radermacher ◽

Jörg Eschweiler

Keyword(s):

Motion Analysis ◽

Humeral Head ◽

Shoulder Joint ◽

Glenohumeral Joint ◽

External Rotation ◽

Initial Study ◽

Biomechanical Behavior ◽

Pneumatic Muscles ◽

Main Component ◽

The Impact

The glenohumeral joint is an important joint with large mobility of the human upperextremity. In shoulder arthroplasty patients often has an unsatisfactory outcome. In order to understand the biomechanical complexity of the shoulder, a novel computer controlled experimental shoulder simulator with an innovative muscle control were constructed. The main component of the simulator includes the active pneumaticmuscles to replicatethe deltoid and the rotator-cuff function and two springs as passive muscle. The aim of this study is to evaluate the impact of a variation of shoulder joint geometries on shoulder biomechanics in the basis of motion analysis. The radius of the glenoid cavity varied from 28-33mm with 2.5mm increment while the radius the humeral head are varied from 20.1-25.1 with 2.5mm increment. The “teach-in” function of the simulator allows an operator to assign the movement to the simulator where the lengths of the pneumatic muscles are recorded. Then the simulator repeats the assigned movement according to the recorded muscles length. The daily living activities includes abduction/adduction, internal/external rotation with adducted arm, and circumduction. The results show promising repeatability of the simulator with minor deviation. However, damage on the surface of the humeral head has been found which should be further studied for both shoulder behavior investigation and the shoulder simulator optimization. Therefore, this study is a decent initial study toward the verification of the simulator and lead to a better understanding of shoulder biomechanical behavior to cope with the clinical problems in the future.

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