An anatomic study of the humeral insertion of the inferior glenohumeral capsule

Glenohumeral translation during active external rotation with the shoulder abducted in cases with glenohumeral instability: a 4-dimensional computed tomography analysis

BACKGROUND

Although glenohumeral instability is common, the mechanism of instability remains unclear. The purpose of this study was to quantitatively evaluate humeral head translation during active external rotation with abduction in patients with glenohumeral instability by use of 4-dimensional computed tomography scans.

METHODS

Ten patients with unilateral glenohumeral instability with a positive fulcrum test were prospectively included in this study. Sequential computed tomography of bilateral shoulders during active external rotation at 90° of shoulder abduction was performed for 6 seconds at 5 frames per second. The 3-dimensional positions of the humeral head center in the anteroposterior, superoinferior, and mediolateral directions were calculated at 0°, 20°, 40°, 60°, and maximum shoulder abduction-external rotation from the starting position. Translation of the humeral head center from the starting position was evaluated using Dunnett multiple-comparison tests, and the differences between the affected and intact shoulders were assessed using Wilcoxon signed rank tests.

RESULTS

The humeral head center translated posteriorly, inferiorly, and medially during glenohumeral external rotation with the shoulder in the abducted position on the intact side. However, the affected humeral head showed significantly less posterior translation (P = .028), greater inferior translation (P = .047), and less medial translation (P = .037) than the contralateral side.

CONCLUSIONS

This study indicated that dysfunction of the anterior band of the inferior glenohumeral ligament causes decreased posterior, increased inferior, and decreased medial translation of the humeral head during active shoulder abduction-external rotation.

Axillary Sonography of the Shoulder: An Adjunctive Approach

Sonography of the shoulder is widely used to assess various disorders, including tendinous diseases of the rotator cuff and the long head of the biceps brachii muscle. The shoulder is commonly explored through anterior, superior, and posterior approaches, but the inferior axillary approach is rarely considered in the literature. However, this technique allows the direct visualization of relevant anatomic structures. The aim of this pictorial essay is, first, to technically describe this approach and the normal musculoskeletal sonographic anatomy of the region and, second, to present the sonographic findings of shoulder disorders that may be helpfully explored this technique.

Ultrasound-guided interventions for painful shoulder: from anatomy to evidence

Shoulder pain is a common musculoskeletal disorder of variable etiology, ranging from rotator cuff pathology to peripheral nerve entrapment. Advances in ultrasound (US) technology have allowed static and dynamic evaluation of shoulder problems and most importantly, offer real-time, radiation-free guidance for interventions. The present review aims to describe shoulder anatomy in detail using information from cadaveric models and to illustrate US-guided techniques using clearly labeled figures and videos. The review will also present evidence of specific US-guided therapies for shoulder pain by summarizing landmark studies, systematic reviews, and meta-analyses. The following shoulder structures will be covered: 1) the biceps long head tendon, 2) the acromioclavicular joint, 3) the subacromial-subdeltoid bursa, 4) the glenohumeral joint, 5) the suprascapular nerve, and 6) the axillary nerve.

Anatomic analysis of the whole articular capsule of the shoulder joint, with reference to the capsular attachment and thickness

Background

Although conventional Bankart repair has been the accepted procedure for traumatic anterior glenohumeral instability, the humeral avulsion of the glenohumeral ligament or an elongation of the capsule remains challenging to decide the appropriate treatment. The anatomical knowledge regarding the whole capsule of glenohumeral joint is necessary to accurately treat for the capsular disorders. The aims of the current study were to investigate the anatomical features of capsular attachment and thickness in a whole capsule of glenohumeral joint.

Methods

We used 13 shoulders in the current study. In 9 shoulders, we macroscopically measured the attachment widths of the capsulolabrum complex on the scapular glenoid, and the attachment widths of the capsule on the humerus in reference to the scapular origin of the long head of triceps brachii, and the humeral insertion of the rotator cuff tendons. We additionally used 4 cadaveric shoulders, which were embalmed using Thiel’s method, for the analysis of the thickness in a whole capsule by using micro-CT.

Results

The glenoidal attachment of the articular capsule appeared to have a consistent width except for the superior part of the origin of the long head of triceps brachii. On the humerus, the articular capsule was widely attached to areas without overlying rotator cuffs, with the widest width (17.3 ± 0.9 mm) attached to the axillary pouch. The inferior part of the capsule, which was consistently thicker than the superior part, continued to the superior part along the glenoid and humeral side edge.

Conclusions

The current study showed that the inferior part of the glenohumeral capsule had a wide humeral attachment from the inferior edge of the subscapularis insertion to the inferior edge of the teres minor insertion via the anatomical neck of the humerus, and the thickness of it was thicker than the superior part of the capsule.

Fracture line morphology of complex proximal humeral fractures

BACKGROUND

The aim of this study was to assess proximal humeral fracture patterns using 3-dimensional computed tomography images and relate them to the normal osseous landmarks and soft-tissue attachments.

METHODS

Forty-eight 3-dimensional computed tomography scans of proximal humeral fractures were retrospectively collected, and the fractures were transcribed onto proximal humeral templates. We analyzed the common location and orientation of the fracture lines, with a focus on fractures of the articular surface, tuberosities, metaphysis, and proximal diaphysis. These fractures were compared with the attachments of the rotator cuff and glenohumeral capsule.

RESULTS

Fifty-two percent of the fractures involved the articular surface. No fractures passed through the bicipital groove, and fractures were more commonly found on the posterior lesser tuberosity and on the anterior greater tuberosity, coinciding with the intervals between the rotator cuff tendon insertions. Intracapsular fractures of the calcar were more common (68%) than extracapsular fractures (32%). On the anterolateral aspect of the proximal humerus, fractures radiated from the articular margin, vertically down through the tuberosity zone between the rotator cuff footprints, meeting horizontally oriented fractures in the metaphyseal zone. On the posterior aspect, vertical fractures from the tuberosity zone continued downward to the metaphyseal zone adjacent to the infraspinatus and teres minor footprints.

CONCLUSIONS

Fractures of the proximal humerus follow characteristic patterns. Fractures frequently split the greater tuberosity and are closely related to the intervals of the rotator cuff attachments.

Anatomy of the capsulolabral complex and rotator interval related to glenohumeral instability

The glenohumeral joint with instability is a common diagnosis that often requires surgery. The aim of this review was to present an overview of the anatomy of the glenohumeral joint with emphasis on instability based on the current literature and to describe the detailed anatomy and anatomical variants of the glenohumeral joint associated with anterior and posterior shoulder instability. A review was performed using PubMed/MEDLINE using key words: Search terms were "glenohumeral", "shoulder instability", "cadaver", "rotator interval", "anatomy", and "anatomical study". During the last decade, the interest in both arthroscopic repair techniques and surgical anatomy of the glenohumeral ligament (superior, middle, and inferior), labrum, and rotator interval has increased. Understanding of the rotator interval and attachment of the inferior glenohumeral ligament on the glenoid or humeral head have evolved significantly. The knowledge of the detailed anatomy and anatomical variations is essential for the surgeon in order to understand the pathology, make a correct diagnosis of instability, and select proper treatment options. Proper understanding of anatomical variants can help us avoid misdiagnosis. Level of evidence V.

Reliability of a set of protractors for direct anatomical measurements around the glenoid and humeral head rims

Functional biomechanics studies of the glenohumeral (GH) soft tissues require an understanding of their sites of bony attachment. Anatomical positions of GH capsular structures have often been quantified relative to the rims of the glenoid and humeral head (HH). The aim of this study was twofold: (1) to quantify the reliability of a set of protractors that directly fit on to the glenoid and HH rims and (2) to use this to determine direct angular position referencing of landmarks and soft tissue attachment points. Three assessors independently used the protractors to assess nine prescribed landmarks on 30 dry bone specimens (15 glenoids and 15 HHs) recording the angular positions of the structures relative to the glenoid and HH. The collected data showed high levels of validity as indicated by the protractor's intra- and inter-assessor reliabilities: 98.2 and 98.7% for the glenoid component, and 96.2 and 96.5% for the humeral component, respectively. The device could be useful in anatomical studies, description of defects and pathologies on glenohumeral articulation, and planning of scapular reconstructive surgery.

Development and validation of a model for quantifying glenohumeral ligament strains during function

Analysis of the function of glenohumeral ligaments (GHLs) during physical joint manipulations is hindered by an inability to adequately image these tissues during the movements. This restricts functional biomechanics studies only to the manoeuvres that may be replicated cadaverically. There is, however, a clinical imperative to be able to investigate complex manoeuvres that exacerbate symptoms but cannot be easily conducted physically in the laboratory. The aim of this study was to develop and validate an algorithm for a computer simulation model that allows the quantification of glenohumeral ligament lengths during function. Datasets of the humerus and scapula pair were segmented to provide individual surface meshes of the bones and insertion points of each glenohumeral ligament on both bones. An algorithm was developed in which the glenohumeral ligament attachment-to-attachment length was divided into two straight lines, plus an arc overlaying the spherical wrapping portions. The model was validated by simulating two classical cadaveric studies from the literature and comparing results. Predictions from the model were qualitatively similar to the results of the two cadaveric studies by a factor of 91.7% and 81.8%, respectively. Algorithm application will allow investigation of functional loading of the glenohumeral ligaments during simulated complex motions. This could then be used to provide diagnostic understanding and thus, inform surgical reconstruction.

Open capsular shift: there still is a role!

As our understanding of the pathoanatomy of glenohumeral instability has improved, surgical techniques for the treatment of anterior instability have progressed. Many stabilization procedures are now successfully performed arthroscopically; open capsular shift, however, continues to play an important role in the management of instability in certain patients, providing an accurate and selective means of capsular plication. When performed with proper surgical technique, shoulder range of motion can be preserved with low recurrence rates and high subjective satisfaction, making the open capsular shift a durable and effective option in the modern management of shoulder instability.

Adduction contracture of the shoulder due to fibrous long head of the triceps in children

OBJECTIVE

To evaluate the clinical and functional results of surgical treatment for fibrous long head of the triceps in children.

MATERIALS AND METHODS

Data were analyzed from 32 patients (38 shoulders) aged over 5 years of age from August 1995 to December 2004. The adduction contracture, elbow flexed angles when the scapula was held in the chest wall, and scapulo-humeral angles in radiographs were measured. Surgical release of the long head of the triceps was performed.

RESULTS

There were 22 females and 10 males in this study. Bilateral shoulder involvement was found in six patients. Only the right shoulder was involved in 5 patients, and only the left in 21 patients. All 32 patients (38 shoulders) developed adduction contracture of the shoulder after repeated intramuscular injection of antibiotic(s) into the long head of the triceps. Thirty-four shoulders (29 patients) were classified as severe, and four shoulders (3 patients) were classified as moderate. In all, we attained excellent results in 36 shoulders (94.7%) and good results in two shoulders (5.3%). There have been no fair or poor results or complications so far.

CONCLUSION

Generally, surgical treatment of adduction contracture of the shoulder has achieved good results, with improved shoulder function. Releasing the long head of the triceps is a simple and safe surgical technique.

Definition of the capsular insertion plane on the proximal humerus

The aim of this work was quantitatively to establish the relationship between the plane that hosts the humeral head lateral margin (anatomical neck) and that of the capsular insertion. Eight cadaveric shoulders were used. These were dissected, exposing the humeral head margin and the root of the capsular humeral insertion to extract digitally their outlines using a mechanical 3-d digitizer. The datasets of the digitized outlines were applied and the geometric planes they best fitted mathematically calculated. Vector analysis techniques were finally applied to the two planes to quantify the relationship between them. The humeral head margin is circular (+/- 2.2% of radius), having each of its outlining points on the same plane (within +/- 1.5 mm.) The capsular attachment outlining points also insert on a plane (+/- 1.4 mm). The two planes are related to one another by an inclination of 14.5 +/- 3.6 degrees. The relationship described here would allow for in vivo prediction of humeral attachment of capsular structures by using radiological datasets of the anatomical neck. This would be useful in patient-specific modelling to study and understand the glenohumeral ligament kinematics during clinical examinations and to plan surgical reconstructive procedures.

Arthroscopic glenohumeral folds and microscopic glenohumeral ligaments: the fasciculus obliquus is the missing link

This study tested the hypotheses that the folds in the inferior glenohumeral capsule appear at the borders and crossings of the underlying capsular ligaments and that embalming may result in misinterpretation of these folds as ligaments. The inferior capsular structures in 80 unembalmed cadaver shoulders were compared with 24 embalmed shoulders. During arthroscopy and dissection, an anteroinferior fold was more prominently seen in internal rotation and was almost obliterated in external rotation. A posteroinferior fold appeared in external rotation and almost disappeared in internal rotation. During dissection, the anteroinferior fold developed at the border of the anterior band of the inferior glenohumeral ligament (ABIGHL) and where this ligament crossed with the fasciculus obliquus (FO). Several patterns of crossing of the ABIGHL and the FO were seen that determined the folding-unfolding mechanism of the anteroinferior fold and the appearance of possible synovial recesses. The axillary part of the IGHL is formed by the FO on the glenoid side and by the ABIGHL on the humeral side. The posteroinferior fold was determined by the posterior band of the IGHL. The folds in the embalmed specimens did not necessarily correspond with the underlying fibrous structure of the capsule. The folds and recesses observed during arthroscopy indicate the underlying capsular ligaments but are not the ligaments themselves. The IGHL complex is formed by its anterior and posterior bands and also by the FO. Both findings are important during shoulder instability procedures because the ligaments need to be restored to their appropriate anatomy and tension. Because the FO may also be involved, Bankart-type surgery may have to reach far inferiorly. Midsubstance capsular shift procedures also need to incorporate this ligament.

An analysis of capsular area in patients with anterior, posterior, and multidirectional shoulder instability

BACKGROUND

Although increased capsular volume has been implicated in shoulder instability, there is a paucity of clinical evidence to quantify the size of the capsule with specific instability conditions of the shoulder.

HYPOTHESIS

Shoulder capsular area, as measured by magnetic resonance arthrography, is increased with specific patterns of shoulder instability.

STUDY DESIGN

Cross-sectional study; Level of evidence, 4.

METHODS

During an 8-month period, all patients with a diagnosis of anterior (n = 19), posterior (n = 14), or multidirectional (n = 13) instability of the shoulder and who were assessed with a magnetic resonance arthrogram were reviewed. A group of 10 control patients without clinical instability were also identified. The magnetic resonance arthrograms of all groups were randomly mixed, and 5 reviewers recorded measures of capsular length and area and determined labral abnormalities. The magnetic resonance arthrogram measurements were compared between groups, and interobserver agreement was determined.

RESULTS

The cross-sectional area of the capsule was increased in patients with posterior (P = .017) or multidirectional instability (P = .021) versus controls, but not in patients with anterior instability. Additionally, the posteroinferior cross-sectional area was increased in patients with posterior (P = .001), multidirectional (P = .003), and anterior (P = .008) instability. In patients with a posterior labral tear, the mean axial (P = .043) and mean posteroinferior sagittal cross-sectional area (P = .011) was increased, but there were no differences in cross-sectional area for those with an anterior labral tear. The overall interobserver reliability was very good (correlation coefficient range, 0.68-0.94).

CONCLUSION

Our results reinforce the concept that capsular elongation and laxity, either preexisting or acquired, play a role in certain instability conditions of the shoulder. Additional work is needed to determine how to correlate surgical decision making with the cross-sectional area measurements demonstrated in this study.

Glenohumeral joint volume reduction with progressive release and shifting of the inferior shoulder capsule

The inferior capsular shift procedure described by Neer is an effective treatment for multidirectional shoulder instability. To determine the amount of volume reduction that occurs with the inferior capsular shift procedure, 13 cadaver shoulders were dissected down to the capsule. A viscous liquid was injected into each shoulder and the baseline volume recorded. A humeral-based capsular release to the 8 o'clock position (right shoulder) was performed, the capsule was shifted, and the volume was recorded. The capsule was released further to the 6 o'clock position and then to the 4 o'clock position. The mean shoulder volume significantly dropped after each successive shift. From baseline, the volume decreased 33% after the first shift, 42% after the second, and 66% after the third. Progressive release of the capsule results in significantly more volume reduction owing to greater elimination of the inferior axillary pouch. A more complete glenohumeral capsular release may be necessary in certain clinical situations.