Biomechanics Of Shoulder Joint Research Articles

Modeling the future of shoulder arthroplasty

BackgroundIn patients with advanced shoulder pathology requiring arthroplasty, the goal is to restore optimal function and provide sustained pain relief. However, the capacity to select the ideal reconstruction of a specific patient’s shoulder and to predict the resulting functional outcome is limited. Computational modeling of the musculoskeletal system has the potential to expand our foundational knowledge of both the native and prosthetic shoulder joint. ObjectiveThe aim of this review is to describe how computational modeling enables more detailed analyses of the interactions between musculoskeletal anatomy and function and to suggest ways in which this approach may be used to optimize outcomes in patients undergoing shoulder arthroplasty. ResultsComputational modeling has been used to study shoulder joint biomechanics for more than 30 years. There are specific limitations that need to be addressed to realize the full potential of computational modeling in shoulder arthroplasty. First, more realistic, patient-specific models of the glenohumeral and scapulothoracic joints must be developed. Second, shoulder models must be coupled with accurate in vivo measurements of joint motion to perform more comprehensive analyses of muscle and joint function. Third, model predictions of shoulder biomechanics must be validated against experimental data. ConclusionPatient-specific musculoskeletal modeling of shoulder joint biomechanics can contribute significantly to predicting pathology and optimizing postoperative function.

METHODS OF INTERPRETATION OF DATA FROM ISOKINETIC TESTS AND MRI STUDIES DURING REHABILITATION OF PATIENTS AFTER RECONSTRUCTIVE SHOULDER JOINT SURGERY

Abstract. The research results in the field of computer visualization of the shoulder joint biomechanics are presented. The possibilities of using biomechanical robotic mechanotherapy on the CON-TREX complex in the rehabilitation treatment of patients after arthroscopic shoulder surgery are shown. The possibilities of additional visualization of magnetic resonance imaging (MRI) data using spectral decomposition methods (Shearlet transform and contrasting with color coding) are studied. Experiments with the use of the proposed diagnostic technique are described. The relationship between the MRI data and CON-TREX protocols in planning and implementation of the rehabilitation procedures is demonstrated. The technique which allows to improve the quality and availability of the MRI data in the study of the shoulder joint biomechanics during restorative treatment is described.

A comparison of glenohumeral joint kinematics and muscle activation during standard and geared manual wheelchair mobility

The high prevalence of upper extremity joint injuries among manual wheelchair users is largely attributed to the high repetitive loading during propulsion. The purpose of this study was to evaluate the effects of using geared wheels for manual wheelchair mobility on shoulder joint biomechanics. Fourteen able-bodied participants performed overground propulsion and ramp ascension using standard and geared manual wheelchair wheels. Spatial temporal parameters, glenohumeral joint kinematics, and shoulder muscle activity were quantified. Findings indicated that regardless of the level of slope, the propulsion speed and stroke distance decreased significantly (p ≪ 0.001), and the stroke frequency increased significantly (p ≤ 0.025) during geared manual wheelchair propulsion. The glenohumeral joint ranges of motion in the coronal plane (p ≤ 0.005) and peak joint angles in the coronal (p ≤ 0.023) and transverse (p ≤ 0.012) planes were significantly different between standard and geared wheels usage. Shoulder muscle activity was substantially less using the geared wheels with significant findings in the pectoralis major (level floor, p ≤ 0.008) and infraspinatus (p ≤ 0.014) peak muscle activity, and the anterior deltoid (p ≤ 0.014) and pectoralis major (p ≤ 0.015) integrated muscle activity. However, the shoulder flexor normalized integrated muscle activity (muscle activity per stroke distance) was not different between the wheels.

‘Superior biceps aponeurosis’—Morphological characteristics of the origin of the short head of the biceps brachii muscle

PurposeOur aim was to characterize the morphology of the proximal attachment of the biceps brachii short head. We hypothesize that it has an aponeurotic component that may affect shoulder joint biomechanics. MethodsThe coracoacromial region and the biceps brachii muscle were dissected in 30 cadaveric shoulders. The course and dimensions of the tendon and aponeurosis were evaluated. The cross-sectional area of the belly of the short head and the length of the whole muscle were measured. Correlations between the aponeurosis and dimensions of the muscle were tested with the Spearman’s rank correlation coefficient. ResultsAponeurosis was present in all specimens, although in 10 cases it was vestigial. The aponeurotic part of the muscle (mean length 90.7 ± 16.3 mm, mean width 12.5 ± 2.9 mm) branched off laterally and traveled to the acromion, blending with the coracoacromial ligament creating the aponeurotic membrane. We named this structure the “superior biceps aponeurosis”. The mean length of the biceps brachii was 31.3 ± 2.1 cm and the mean cross-sectional area of the short head was 210.7 ± 54.3 mm2. The dimensions of the “superior biceps aponeurosis” correlated positively with the cross-sectional area of the muscle (R2 from 0.37 to 0.52, p from 0.014 to 0.001). ConclusionThe origin of the short head of the biceps brachii muscle has a varied aponeurotic component combining the aponeurotic part of the muscle and the aponeurotic membrane. Together, they create the “superior biceps aponeurosis”. Clinical relevanceThe morphology of the origin of the biceps brachii short head is relevant in Bristow/Latarjet procedures. This aponeurotic component may affect the shoulder joint biomechanics after the coracoid process transfer.

A retrospective analysis of extra articular glenoid neck fracture of scapula (A study of 20 cases)

Introduction: Since long ago the scapula fracture is treated conservatively and most of time it works because scapula is a flat bone and coated with bulky muscle. So, nonunion of the fracture is usually not a problem, and most of time, due to very high arc of motion of shoulder joint, even in malunited fractures, mild to moderate restriction of the range of motion not create significant problem. But the actual problem comes when fracture through the glenoid neck or glenoid fossa cause derangement in the biomechanics of shoulder joint, or associated fracture of clavicle – ‘The floating shoulder’ cause significant instability of shoulder joint. Recent advances and proper understanding of the biomechanics of the shoulder joints open a new chapter of operative management for better quality of life.In this study we retrospectively tried to understand that which fractures can be treated conservatively and which one require fixation.Aim: To study retrospectively extraarticular glenoid neck fractures of scapula (a study of 20 cases).Materials and Methods: Total 20 patients having extra articular scapular neck fracture, with following criteria are included in this study. All patients were treated by consultant orthopedic surgeons of the department of orthopedics of Guru Gobindsingh Hospital, Jamnagar only. All patients are evaluated retrospectively. Patients having fracture of appendicles (Fracture of acromion, coracoid and spine), body as well as intra articular glenoid fracture were not included in this study. So this study was concerned only with stable and unstable scapular neck fracture. All patients are evaluated with Herscovici shoulder scoring system to make this study comparable with other study universally.Results: Our study shows excellent results in 16 out of 20 scapular fractures as well as 4 good results, according to Herscovici shoulder scoring system. Most common complication is subacromial pain especially at night while sleeping on that side. Incidence of mild exertional pain is 45% while loss of useful abduction was 10% and superficial infection is 5%.Conclusion: To conclude, this rare type of fracture has high incidence of significant associated injury. Among all scapular fractures extra articular displaced glenoid fracture and floating shoulder type injury should get special attention regards of its treatment, because closed observation and intelligence can make vast change in its outcome.

Passive contribution of the rotator cuff to abduction and joint stability

The purpose of this study is to compare shoulder joint biomechanics during abduction with and without intact non-functioning rotator cuff tissue. A cadaver model was devised to simulate the clinical findings seen in patients with a massive cuff tear. Eight full upper limb shoulder specimens were studied. Initially, the rotator cuff tendons were left intact, representing a non-functional rotator cuff, as seen in suprascapular nerve paralysis or in cuff repair with a patch. Subsequently, a massive rotator cuff tear was re-created. Three-dimensional kinematics and force requirements for shoulder abduction were analyzed for each condition using ten abduction cycles in the plane of the scapula. Mediolateral displacements of the glenohumeral rotation center (GHRC) during abduction with an intact non-functioning cuff were minimal, but massive cuff tear resulted in significant lateral displacement of the GHRC (p < 0.013). Similarly, massive cuff tear caused increased superior migration of the GHRC during abduction compared with intact non-functional cuff (p < 0.01). From 5 to 30° of abduction, force requirements were significantly less with an intact non-functioning cuff than with massive cuff tear (p < 0.009). During abduction, an intact but non-functioning rotator cuff resulted in decreased GHRC displacement in two axes as well as lowered the force requirement for abduction from 5 to 30° as compared with the results following a massive rotator cuff tear. This provides insight into the potential biomechanical effect of repairing massive rotator cuff tears with a biological or synthetic "patch," which is a new treatment for massive cuff tear.

Virtual Power Based Algorithm for Decoupling Large Motions from Infinitesimal Strains: Application to Shoulder Joint Biomechanics

New trends of numerical models of human joints require more and more computation of both large amplitude joint motions and fine bone stress distribution. Together, these problems are difficult to solve and very CPU time consuming. The goal of this study is to develop a new method to diminish the calculation time for this kind of problems which include calculation of large amplitude motions and infinitesimal strains. Based on the Principle of Virtual Power, the present method decouples the problem into two parts. First, rigid body motion is calculated. The bone micro-deformations are then calculated in a second part by using the results of rigid body motions as boundary conditions. A finite element model of the shoulder was used to test this decoupling technique. The model was designed to determine the influence of humeral head shape on stress distribution in the scapula for different physiological motions of the joint. Two versions of the model were developed: a first version completely deformable and a second version based on the developed decoupling method. It was shown that biomechanical variables, as mean pressure and von Mises stress, calculated with the two versions were sensibly the same. On the other hand, CPU time needed for calculating with the new decoupled technique was more than 6 times less than with the completely deformable model.