Attachment of the anteroinferior glenohumeral ligament-labrum complex to the glenoid: an anatomic study

A cadaveric study of the posterior band of the inferior glenohumeral ligament of the shoulder and its dynamic behaviour in different arm positions

Purpose

The inferior glenohumeral ligament (IGHL) is composed of three parts: the anterior branch or band (AB), the axillary pouch and the posterior band (PB). The latter has rarely been studied. We aim to describe the PB of the IGHL and its dynamic behaviour in different arm positions.

Methods

Twelve fresh cadaveric shoulders were used and the two bands (AB and PB) of the IGHL were dissected and isolated, taking away all muscle, ligaments and capsule. Characteristics of the bands were studied in five positions: maximum external rotation (ER1), abduction (ABD), internal rotation (IR), ABD external rotation (ER2) and anterior elevation-adduction-IR (Hawkins-Kennedy test position). Progressive and randomized sectioning of the bands and capsule with a scalpel was performed to study its impact on mobility and translation of the glenohumeral joint.

Results

The bands that tensioned first were in ER1, the AB at 97 ± 9° (80-110); in ER2, the AB at 81 ± 19° (30-100); in IR, the PB at 64 ± 9° (50-80); and in ABD, the PB at 87 ± 10° (70-105). Isolated sectioning of the AB had no effect on ABD, whilst isolated sectioning of the PB allowed greater ABD. In ER2, the AB limited anterior translation. After sectioning the AB, anterior translation remained limited by the PB, which wrapped around the humeral head and locked the joint by pressing the two joint surfaces tightly together. In Hawkins-Kennedy position anterior elevation-adduction-IR, the AB is the first constraint and the posterior translation was limited by the PB alone only in four cases.

Conclusions

When the IGHL is isolated, ligament limitation of glenohumeral ABD seems to be uniquely dependent on the PB. In the Hawkins and Kennedy position, the AB is the first constraint. In the case of an isolated lesion to the AB, the PB participates in anterior stabilization of the shoulder by wrapping around the humeral head that cannot dislocate. These findings confirm the role of the PB in glenohumeral joint stability.

Level of Evidence

Level IV.

Development of a novel animal model of rotator cuff tear arthropathy replicating clinical features of progressive osteoarthritis with subchondral bone collapse

OBJECTIVE

To establish an animal model of modified cuff tear arthropathy (mCTA) in order to better replicate the pathophysiology associated with rotator cuff tear-induced humeral head collapse.

DESIGN

mCTA was induced by transection of the rotator cuff, the long head of the biceps brachii (LHB), and superior half of the joint capsule in the right shoulder of 12-week-old rats; the left shoulder underwent sham surgery. The severity of CTA was quantitated using the Murine Shoulder Arthritis Score (MSAS). The trabecular bone of the humeral head and metaphysis was analyzed using bone histomorphometry. The expression of proinflammatory cytokines and catabolic enzymes was evaluated immunohistochemically.

RESULTS

In the mCTA model, the MSAS increased starting from 2 weeks after induction, and there was notable subchondral bone collapse with fibrous cells at 4 weeks. The mCTA cartilage exhibited positive staining for TNF-α, IL-1β/6, MMP-3/13, and ADAMTS5. The trabecular bone volume was reduced not only in the subchondral bone but also in the metaphysis of the humeri, and bone resorption was enhanced in these areas. In the collapsed subchondral bone, both bone formation and resorption were increased. The fibrous cells showed expression of TNF-α, IL-6, and MMP-13, along with specific markers of mesenchymal stem cells. Furthermore, the fibrous cells showed osteoblastic characteristics (RUNX2-positive) and expressed RANKL.

CONCLUSIONS

The LHB and the capsuloligamentous complex are critical stabilizers of the glenohumeral joint, serving to prevent the advancement of CTA following massive rotator cuff tears. Fibrous cells appear to play a role in the humeral head bone resorption.

Arthroscopic Bankart repair with additional footprint fixation using the double-row technique at the 4 o'clock position anatomically restored the capsulolabral complex and showed good clinical results

PURPOSE

To investigate the clinical outcome and magnetic resonance imaging (MRI) findings after arthroscopic Bankart repair with additional double anchor footprint fixation (DAFF) at the 4 o'clock position, where the native footprint is widest anatomically, for recurrent anterior shoulder instability.

METHODS

Forty-two patients (mean age 27.0 years) with recurrent anterior shoulder instability and without severe glenoid bone defects underwent arthroscopic Bankart repair with additional DAFF at the 4 o'clock position. Using three standard portals, single-row repair was performed at the 2, 3, and 5 o'clock positions, and DAFF with the suture bridging technique was conducted at the 4 o'clock position. MRI was performed preoperatively and at 6 months postoperatively. Patients with follow-up periods of ≥1 year were included in the present study and clinically evaluated at the final follow-up. The morphology at the 2 and 4 o'clock positions on radial MRI slices was compared between the preoperative and 6-month postoperative scans, and the footprint of the repaired capsulolabral complex at 6 months postoperatively was compared between the 2 and 4 o'clock positions.

RESULTS

The average follow-up period was 19.5 ± 6.2 months. The rates of dislocation recurrence and positive apprehension test results were 2.4 and 4.8%, respectively. External rotation was restricted by 3.5°. The University of California at Los Angeles and Rowe scores at the final follow-up were 34.5 ± 1.0 points and 97.2 ± 5.7 points, respectively, representing significant improvements over the preoperative scores (p < 0.01). Although the capsulolabral complex at 6 months postoperatively was firmly repaired at both the 2 and 4 o'clock positions compared to its preoperative state, the footprint of the restored capsulolabral complex was wider at the 4 o'clock position than at the 2 o'clock position (p < 0.01).

CONCLUSIONS

Additional DAFF at the 4 o'clock position improved the glenohumeral stability and function of the shoulder joint. This study suggests that this technique is a reliable and useful treatment for shoulder instability.

LEVEL OF EVIDENCE

IV.

Effect of Anterior Glenoid Chondrolabral Defects on Anterior Glenohumeral Stability: A Biomechanical Study

Background:

It is well known that glenoid osseous defects >13.5% of the glenoid width critically destabilize the shoulder, as do labral tears. Chondrolabral defects often occur with anterior dislocation of the shoulder. It is unclear whether glenoid chondrolabral defects contribute to shoulder stability and, if so, at what size they become critical.

Purpose/Hypothesis:

The purpose of this study was to determine the effect of incremental chondrolabral defect sizes on anterior shoulder stability in the setting of labral deficiency. The hypothesis was that chondrolabral defects ≥13.5% of the glenoid width will decrease anterior shoulder stability.

Study Design:

Controlled laboratory study.

Methods:

This controlled laboratory study tested 12 fresh-frozen shoulders. Specimens were attached to a custom testing device in abduction and neutral rotation with 50-N compression applied to the glenoid. The humeral head was translated 10 mm anterior, anteroinferior, and anterosuperior with the conditions of intact cartilage and labrum and anterior full-thickness chondrolabral defects of 3-, 6-, and 9-mm width. Translation force was measured continuously. Peak translation force divided by 50-N compressive force defined the stability ratio. Data were analyzed using analysis of variance.

Results:

The anterior stability ratio decreased between the intact state (36% ± 7%) and all defects ≥3 mm (≤32% ± 8%; P ≤ .023). The anteroinferior stability ratio decreased between the intact state (52% ± 7%) and all defects ≥3 mm (≤47% ± 7%; P ≤ .006). The anterosuperior stability ratio decreased between the intact state (36% ± 4%) and all defects ≥6 mm (≤33% ± 4%; P ≤ .006). A 3-mm defect equated to 10% of the glenoid width. There were moderate to strong negative correlations between chondrolabral defect size and stability ratio in the anterior, anteroinferior, and anterosuperior directions (r = –0.79, –0.63, and –0.58, respectively; P ≤ .001). There were moderate to strong negative correlations between the percentage of glenoid chondrolabral defect size to the glenoid width and the stability percentage in all directions (r = –0.81, –0.63, and –0.61; P ≤ .001).

Conclusion:

An anterior glenoid chondrolabral defect ≥3 mm (>10% of the glenoid width) significantly decreased anterior and anteroinferior stability. Chondrolabral defect size negatively correlated with stability.

Clinical Relevance:

To fully restore glenohumeral stability, in addition to labral repair, it may be necessary to reconstruct chondrolabral defects as small as 3 mm (10% of the glenoid width).

Morphology of Glenoid Cartilage Defects in Anteroinferior Glenohumeral Instability

Background:

Glenoid cartilage defects may contribute to anterior shoulder instability recurrence and progression to osteoarthritis, but their morphology remains unknown.

Purpose/Hypothesis:

The purpose was to determine the shape, size, and location of glenoid cartilage defects and the prevalence and risk factors for cartilage defects in the setting of anterior glenohumeral instability. It was hypothesized that glenoid cartilage defects would be common, would be associated with recurrence of dislocation, and would share similar morphology with glenoid osseous defects.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

In this retrospective study, all patients who underwent arthroscopic surgical treatment for anterior glenohumeral instability between January 2012 and May 2019 were included; excluded were patients with documented posterior or multidirectional instability or previous glenohumeral surgery. For each patient, the operative report, arthroscopic images, and preoperative magnetic resonance imaging (MRI) scans were reviewed to determine the prevalence of cartilage injury. For those patients with an Outerbridge grade 3 or 4 defect, the cartilage surfaces on the MRI scans were segmented to make 3-dimensional (3-D) segmentations. From these 3-D segmentations, we measured length, width, and surface area of the glenoid and defect, and the orientation of the defect relative to the superior and inferior poles of the glenoid. A multivariable analysis was conducted to determine correlates with cartilage damage.

Results:

In 322 patients treated operatively for anterior glenohumeral instability, 38% had a concomitant cartilage defect. The mean cartilage defect was located directly anteriorly at the 3:07 clockface position (range, 2:10-4:05) and encompassed 6.5% ± 3.5% of the glenoid surface area. However, defects ranged up to >56% of glenoid length and up to 27% of glenoid width, and the largest defect encompassed 19.5% of the glenoid cartilage surface area. Patients with a cartilage defect were more likely to be male (P = .031) and to have undergone a concomitant posterior labral repair (P = .018).

Conclusion:

Cartilage defects were common in patients with operatively treated anterior glenohumeral instability, occurring in 38% of patients. These defects were located directly anteriorly at 3:07, similar to osseous glenoid defects. Future prospective studies with cartilage-specific MRI sequences should be conducted.

Permeable spaces between glenohumeral ligaments as potential gateways for rapid regional anesthesia of the shoulder

Shoulder pain is a highly prevalent condition, often resulting in major life limitations, and requiring effective treatments. In this work, we explore the anatomical basis of a proposed approach to the regional anesthesia of the shoulder through a single injection under the subscapularis muscle. Bilateral experimental injections in shoulders from body donors (Radiolar ® and Methylene-Blue) under the subscapular muscle (n = 11) and cadaveric systematic dissections of other 35 shoulders from body donors were performed. Injectate spread was then qualitatively assessed. Long axis of permeable foramina in the anterior aspect of the shoulder joint capsule was measured in centimeters using a digital caliper. More than 40% of specimens had at least one permeable space (Weitbrech and/or Rouvière foramina) communicating the subscapular bursa and the articular space. We further demonstrate that an ultrasonography-guided injection under the subscapularis muscle allows the spread of the injectate through the anterior, inferior and posterodorsal walls of the articular capsule, the subacromial bursa, and the bicipital groove, as well as into the articular space for some injections. The odds of accidental intraarticular injection decrease when injecting with low volumes. This anatomical study provides a detailed description of foramina between glenohumeral ligaments. Furthermore, the data shown in this work supports, as a proof of concept, a safe alternative for rapid and specific blockade of terminal sensory branches innervating the shoulder joint capsule.

Evaluation of variations of the glenoid attachment of the inferior glenohumeral ligament by magnetic resonance arthrography

Objective

To evaluate the anatomical variations of the attachment of the inferior glenohumeral ligament (IGHL) to the anterior glenoid rim.

Materials and Methods

This was a retrospective review of 93 magnetic resonance arthrography examinations of the shoulder. Two radiologists, who were blinded to the patient data and were working independently, read the examinations. Interobserver and intraobserver agreement were evaluated. The pattern of IGHL glenoid attachment and its position on the anterior glenoid rim were recorded.

Results

In 50 examinations (53.8%), the glenoid attachment was classified as type I (originating from the labrum), whereas it was classified as type II (originating from the glenoid neck) in 43 (46.2%). The IGHL emerged at the 4 o'clock position in 58 cases (62.4%), at the 3 o'clock position in 14 (15.0%), and at the 5 o'clock position in 21 (22.6%). The rates of interobserver and intraobserver agreement were excellent.

Conclusion

Although type I IGHL glenoid attachment is more common, we found a high prevalence of the type II variation. The IGHL emerged between the 3 o'clock and 5 o'clock positions, most commonly at the 4 o'clock position.

Inferior Glenohumeral Ligament (IGHL) Injuries: A Case Series of Magnetic Resonance (MR) Imaging Findings and Arthroscopic Correlation

Introduction

The inferior glenohumeral ligament (IGHL) complex commonly is assessed by both magnetic resonance imaging (MRI) and magnetic resonance (MR) arthrogram. Our study compared the accuracy of MR arthrogram compared to MRI using arthroscopic correlation as the gold standard.

Methods

A retrospective review of cases reporting an IGHL injury was performed. Seventy-seven cases met inclusion criteria, while five had arthroscopic reports that directly confirmed or refuted the presence of IGHL injury. Two arthroscopic reports confirmed concordant IGHL injuries, while three arthroscopic reports mentioned discordant findings compared to MR. All three discordant cases involved MR arthrogram. Findings included soft tissue edema, fraying of the axillary pouch fibers, and cortical irregularity of the humeral neck. Of the two concordant cases, one was diagnosed by MRI, revealing an avulsion of the anterior band, while the second was diagnosed by MR arthrogram showing ill-defined anterior band fibers. Many cases involved rotator cuff or labral tears, which may have been the focus of care for providers, given their importance for shoulder stability. Additionally, a lack of diagnostic confidence in MR reports may have influenced surgeons in the degree to which they assessed the IGHL complex during arthroscopy.

Conclusion

Radiologists seemed more likely to make note of IGHL injuries when MR arthrograms were performed; meanwhile, all three discordant cases involved MR arthrogram reads. Therefore, additional larger studies are needed with arthroscopic correlation to elucidate MR findings that confidently suggest injury to the IGHL complex, to avoid false positive radiology reports.

Anatomic Analysis of the Attachment of the Posteroinferior Labrum and Capsule to the Glenoid: A Cadaveric Study

PURPOSE

To measure the height of the posteroinferior glenohumeral ligament (PIGHL) attachment to the labrum and the depth of the posteroinferior labrum to the glenoid, macroscopically, and to investigate the morphology of the attachment of the posteroinferior labrum to the glenoid, histologically.

METHODS

Fifty cadaveric shoulders without exposed subchondral bone on the glenoid and detached posterior labrum were used. We examined the frequency of the heights of the PIGHL attachments to the labrum and the length of the labral attachment on the glenoid rim at the 7, 8, 9, and 10 o'clock positions, macroscopically. According to morphology of the histological labral attachments, it was divided into 3 groups. Labra attached on the articular surface and the glenoid neck were defined as the SN type, while labra attached only to the glenoid neck constituted labra attached to the bone and side of the articular cartilage (Nc type) and labra attached only to bone (Nb type).

RESULTS

The PIGHL attached from 7 o'clock to 9 o'clock in 48 shoulders (96%). The mean labral attachment at the 7 o'clock position was 6.3 ± 1.0 mm (range, 4.6-9.4 mm), which was significantly longer than at the other positions (P < .05). Histologically, the frequency of SN type attachment was 49 (98%) shoulders at the 7 o'clock position.

CONCLUSIONS

The PIGHL attached between 7 and 9 o'clock in 96% of the shoulders. In 98% of the shoulders, the labrum did not attach to the articular surface, but attached to both the articular cartilage and the bone of the glenoid neck at 7 o'clock.

CLINICAL RELEVANCE

The posteroinferior labrum should be repaired widely at the 7 o'clock position and not on the articular surface because the labrum attached anatomically to the glenoid neck.

The glenohumeral micromotion and influence of the glenohumeral ligaments during axial rotation in varying abduction angle

BACKGROUND

The patients with shoulder instability or disorders in overhead athletes have been considered to have an abnormal micromotion at the glenohumeral joint. However, the normal range of the micromotion has not been available during axial rotation with various abduction angles, especially above 90° abduction. This study aimed to investigate the glenohumeral translation and influence of the glenohumeral ligaments during axial rotation with up to maximum abduction.

METHODS

Fourteen healthy volunteers performed active axial rotations at 0°, 90°, 135°, and maximal abduction angles. The positions of the humeral head center relative to the glenoid at maximally external, neutral, and maximally internal rotations (ER, NR, IR, respectively) for each abduction angle were evaluated using two- (2D) and three-dimensional (3D) shape matching registration techniques. The shortest pathway and its length between the origin and insertion of the superior, middle, and inferior glenohumeral ligaments (SGHL, MGHL, and IGHL, respectively) were calculated for each position.

RESULTS

The glenohumeral joint showed 3.1 mm of superoinferior translation during axial rotation at 0° abduction (P < 0.0001), and 2.6 mm and 4.5 mm anteroposterior translation at 135° and maximal abduction (P < 0.0001), respectively. The SGHL and MGHL reached a maximum length at ER with 0° abduction, and the anterior and posterior bands of the IGHL reached a maximum at ER with 90° abduction and IR with 0° abduction.

CONCLUSIONS

These findings indicated that the SGHL played a role as an inferior suppressor at 0° abduction, while the anterior band of IGHL played a role as an anterior stabilizer at 90° abduction. Every glenohumeral ligament did not get taut and the anteroposterior translation became greater with increasing abduction angle, above 90°. These results could be used as a reference when comparing with the pathological shoulders in the future study.

Quantitative and Qualitative Analyses of the Glenohumeral Ligaments: An Anatomic Study

BACKGROUND

While several studies have qualitatively described the anatomy of the glenohumeral ligaments, there remains a lack of consensus regarding their quantitative humeral and glenoid attachment sites.

PURPOSE

To quantitatively and qualitatively describe the anatomic humeral and glenoid attachment sites of the glenohumeral ligaments and their relationship to well-established anatomic landmarks.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 10 nonpaired, fresh-frozen human cadaveric shoulders were included in this study. A 3-dimensional coordinate measuring device was used to quantify the location of pertinent bony landmarks and soft tissue attachment areas. All subcutaneous tissues and musculature were removed, with the exception of the rotator cuff (respective muscle bellies cut at their musculotendinous junctions) and the long head of the biceps tendon. The superior glenohumeral ligament (SGHL), middle glenohumeral ligament (MGHL), anteroinferior glenohumeral ligament (AIGHL), posteroinferior glenohumeral ligament (PIGHL), and coracohumeral ligament (CHL) were then transected. Coordinates of points along the perimeters of attachment sites were used to calculate areas, while coordinates of center points were used to determine distances between surgically relevant attachment sites and pertinent bony landmarks.

RESULTS

The mean length of the SGHL humeral attachment along the intra-articular cartilage margin was 9.5 ± 3.2 mm, spanning from 12:55 to 1:40, while the SGHL glenoid attachment to the labrum was 1.9 ± 1.2 mm medial to the most lateral extent of the labral rim, spanning from 12:30 to 12:45. The mean length of the MGHL attachment along the intra-articular cartilage margin was 16.4 ± 3.0 mm, equating to 2:10 to 3:35 on the humeral head clockface, and the glenoid attachment was confluent with the labrum, attaching 1.5 ± 1.0 mm medial to the most lateral extent of the labral rim and thus extending from 1:50 to 2:35 on the glenoid clockface. The mean length of the AIGHL attachment along the intra-articular cartilage margin was 12.0 ± 3.0 mm, spanning from 4:05 to 5:10 on the humeral head clockface. The AIGHL bony footprint on the glenoid neck was 48.4 ± 24.5 mm². The confluent attachment of the AIGHL to the labrum was 1.2 ± 0.9 mm medial to the most lateral extent of the labral rim, corresponding to 3:30 to 4:05 on the glenoid clockface. The mean length of the PIGHL attachment along the intra-articular cartilage margin was 12.0 ± 1.4 mm, spanning from 7:40 to 8:50 on the humeral head clockface. The PIGHL attachment to the labrum was 1.2 ± 0.5 mm medial to the most lateral extent of the labral rim. This attachment to the labrum was calculated to span from 7:35 to 8:50 on the glenoid clockface. The mean length of the CHL origin from the coracoid was 12.9 mm, with its most anterior point located a mean of 14.1 mm from the tip of the coracoid. The mean length of the CHL attachment along the intra-articular cartilage margin was 10.0 ± 4.0 mm, spanning from 11:55 to 12:40 on the humeral head clockface.

CONCLUSION

Glenohumeral ligaments were consistently identified in all specimens with minor anatomic variability for the SGHL, MGHL, AIGHL, and PIGHL. Important landmarks including the cartilage surface of the humerus, the bicipital groove, and the clockface can be utilized intraoperatively when attempting anatomic repair of these structures.

CLINICAL RELEVANCE

There are multiple open and arthroscopic shoulder procedures that rely on anatomic restoration of these static stabilizers to provide optimal shoulder function and prevent recurrent instability. The qualitative descriptions are comparable with current literature; however, this study is the first to quantify the glenohumeral capsular and ligamentous attachments. The data provided allow for reliable landmarks to be established from known bony and soft tissue structures.

Anchor placement to glenoid rim during Bankart repair recreates contact area of anterior capsulolabral complex on glenoid better than onto articular surface

PURPOSE

This study aimed to compare the contact areas of Bankart repair with suture anchors placed on the articular surface of the glenoid versus at the rim of the glenoid because it is unclear which technique most effectively restores the footprint after Bankart repair.

METHODS

Ten fresh frozen cadaveric shoulders (mean age 70.7 years) were dissected. The attachment site of the capsulolabral complex from the 1 o' clock position to the 6 o'clock position was marked with ink, and the contact area of the anterior-inferior capsulolabral complex on the glenoid neck was measured using imageJ. Bankart lesions were created, and two types of Bankart repair were performed on each specimen. The suture anchors were inserted at the glenoid rim (Rim group) and onto the glenoid articular surface 2 mm from the rim (Surface group). Using pressure-sensitive films, we examined the interface contact area.

RESULTS

The Rim group recreated 64.9% of the native surface area, while the Surface group recreated 47.3% of the area. The Rim group recreated significantly greater contact area compared to the Surface group (P = 0.0008).

CONCLUSION

The anchor placement to the glenoid rim recreates the footprint of the capsulolabral complex on the anterior inferior glenoid better than the anchor placement onto the articular surface.

Postoperative MR Imaging in Shoulder Instability and Intra-articular Damage

MR imaging of the postoperative shoulder after instability surgery is challenging. The radiologist must be familiar with surgical procedures, altered anatomy, and expected postoperative findings for correct interpretation of normal findings versus a true pathology. Artifacts from metallic hardware or abrasions further complicate MR image interpretation, but are reduced with metal artifact reduction techniques. This article focuses on capsulolabral surgery, bone block transfers, and humeral bone loss procedures in patients with shoulder instability and their postoperative imaging evaluation. Surgical procedures and common complications are explained, and normal and pathologic postoperative imaging findings are presented.

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.

Systematic Review of the Anatomic Descriptions of the Glenohumeral Ligaments: A Call for Further Quantitative Studies

PURPOSE

To perform a systematic review of the glenohumeral ligament anatomic attachments on the glenoid and humeral neck.

METHODS

A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed, MEDLINE, and Embase from 1980 to present. The inclusion criteria were as follows: cadaveric or clinical anatomic studies that qualitatively or quantitatively described the glenoid and humeral attachments of the glenohumeral ligaments in the English-language literature. Imaging and animal studies, editorial articles, and surveys were excluded from this study.

RESULTS

The 15 included studies analyzed a total of 983 shoulders. Only 5 studies reported quantitative measurements. The most common glenoid superior glenohumeral ligament attachment described was in the anterolateral region of the supraglenoid tubercle and was inserting on the humerus in close vicinity to the subscapularis tendon insertion. The superior labrum and lesser tuberosity were the most commonly reported middle glenohumeral ligament attachments. The inferior glenohumeral ligament was most commonly described to attach between the 2- and 4-o'clock positions of the glenoid and distally near the surgical neck of the humerus.

CONCLUSIONS

There were limited quantitative data on the attachments of the glenohumeral ligaments. Although the literature was discordant, the most common descriptions of the attachments were as follows: The anterolateral region of the supraglenoid tubercle, the superior labrum, and the glenoid (between the 2- and 4-o'clock positions) were the medial attachments for the superior glenohumeral ligament, middle glenohumeral ligament, and inferior glenohumeral ligament, respectively. Laterally, they inserted on the humerus in close vicinity to the subscapularis tendon insertion, on the lesser tuberosity, and near the surgical neck of the humerus, respectively.

CLINICAL RELEVANCE

The glenohumeral ligaments are important anatomic structures contributing to the dynamic stability of the glenohumeral joint. Further detailed quantitative descriptions of their attachments are required for truly anatomically based repairs.

The effect of subscapularis muscle contraction on coaptation of anteroinferior glenohumeral ligament-labrum complex after Bankart repair

Facilitation of healing is important for the anteroinferior glenohumeral ligament-labrum complex (AIGHL-LC) after Bankart repair in shoulder dislocation. The purpose of this study was to investigate the effect of subscapularis muscle loading on contact area and contact pressure between the subscapularis and AIGHL-LC and between the glenoid bone and the AIGHL-LC following Bankart repair. Twenty-two fresh-frozen cadaveric shoulders were used. They were attached to a shoulder-positioning device to which a compression force was applied. Loads applied to the supraspinatus, infraspinatus, and teres minor tendons were held constant. The loads applied to the subscapularis tendon were set at 0, 10, 20, and 30 Newton (N). Contact pressure and area between the subscapularis and the AIGHL-LC were measured with the arm at 4 rotational positions: 60° and 30° internal, neutral, and 30° external. After the Bankart lesion was created, the contact area and pressure between the AIGHL-LC and glenoid bone were measured while Bankart repair was performed with or without loading of the subscapularis. The contact area and pressures with 10, 20, and 30 N of subscapularis loadings were significantly greater than with 0 N of subscapularis loading at 60° internal rotation and 30° external rotation (P < .05). After Bankart repair, contact area and pressure with subscapularis loading between the AIGHL-LC and glenoid bone were significantly greater than without subscapularis loading (P < .01). We conclude that isometric contraction exercises of the subscapularis might facilitate healing of the AIGHL-LC after Bankart repair.

Revisiting the Anterior Glenoid: An Analysis of the Calcified Cartilage Layer, Capsulolabral Complex, and Glenoid Bone Density

PURPOSE

In this cadaveric study, we aim to define the basic anatomy of the anterior glenoid with attention to the relationships of calcified cartilage, capsulolabral complex, and osseous morphology of the anterior glenoid.

METHODS

Seventeen cadaveric glenoid specimens (14 male, 3 female, mean age 53.9 ± 10) were imaged with micro-computed tomography (CT) and embedded in poly-methyl-methacrylate. Specimens were included for final analysis only if the entire glenoid articular cartilage, labrum, capsule, and biceps insertion were pristine and without evidence of injury, degeneration, or damage during the preparation process. Group 1 members (n = 9) were axially sectioned through 3 to 9 o'clock and 4 to 8 o'clock; group 2 members (n = 8) were radially sectioned through 3, 4, 5, and 9 o'clock. A scanning electron microscope (SEM) analysis quantified the percentage of bone within a 5 × 2.5 mm region at the glenoid rim. Micro-CT, SEM, and light microscopy evaluated the capsulolabral complex and calcified fibrocartilage.

RESULTS

A 7 ± 2.1 mm region of calcified fibrocartilage at 4 o'clock was identified from the articular face to the medial glenoid neck supporting the overlying capsulolabral footprint and was >3× thicker at the articular attachment (316 ± 153 μm) versus the glenoid neck (92 ± 66 μm). At 3 to 9 o'clock and 4 to 8 o'clock 79.2% ± 5.4% and 75.2% ± 7.8% of the glenoid osseous width was covered with articular cartilage. The labrum accounted for 13.1% ± 3.4% of the glenoid width at 4 o'clock. SEM analysis demonstrated decreased glenoid bone density at 3, 4, and 5 o'clock (P ≤ .015) and no difference (P = .448) at 9 o'clock versus central subchondral bone.

CONCLUSIONS

The capsulolabral footprint contributes significantly to the glenoid face, inserts directly adjacent to the articular cartilage, and extends medially along the glenoid neck. A layer of calcified fibrocartilage lies immediately beneath the capsulolabral footprint and is 3× thicker at the articular insertion compared with the glenoid neck. Lastly, there is a bone density gradient at the anterior-inferior rim versus the central subchondral bone.

CLINICAL RELEVANCE

Arthroscopic Bankart repair has been reported to have a significant failure rate in many settings. It is felt that reproducing anatomy with the repair could help improve outcomes. Based on this study's findings, an arthroscopic Bankart technique that most closely reproduces native anatomy and potentially optimizes soft-tissue healing could be performed. This includes removal of 1 to 2 mm of articular cartilage from the glenoid face with anchor placement at this location to appropriately reposition the capsulolabral complex.

The Rotator Cuff and the Superior Capsule: Why We Need Both

Tears of the rotator cuff are frequent. An estimated 250,000 to 500,000 repairs are performed annually in the United States. Rotator cuff repairs have been successful despite fatty infiltration and atrophy of the rotator cuff muscles. Although the emphasis in rotator cuff repair has historically focused on re-establishing the tendon attachment, there is growing interest in and understanding of the role of the superior capsule. The superior capsule is attached to the undersurface of the supraspinatus and infraspinatus muscle-tendon units, and it resists superior translation of the humeral head. Herein, we propose that it is the defect in the superior capsule that is the "essential lesion" in a superior rotator cuff tear, as opposed to the defect in the rotator cuff itself. We propose that rotator cuff repair must restore the normal capsular anatomy to provide normal biomechanics of the joint and thus a positive clinical outcome.

What can the Radiologist do to Help the Surgeon Manage Shoulder Instability?

Imaging of the shoulder forms an important adjunct in clinical decision making in patients with shoulder instability. The typical lesions related with classic anterior and anteroinferior shoulder dislocation are an anteroinferior labral avulsion with or without bony fragment of bone loss – a (bony) Bankart lesion – and a posterolateral humeral head impaction fracture – the Hill-Sachs lesions. These are relatively straightforward to identify on imaging, although normal variants of the inferior labrum and variants of labral damage may cause confusion. Other capsuloligamentous lesions, often associated with less typical types of instability, are much more difficult to identify correctly on imaging, as they occur in the anterosuperior part of the glenohumeral joint with its many normal variants or because they result in more subtle, and therefore easily overlooked, changes in morphology or signal intensity. This paper aims at describing the appearance of the normal and pathologic glenohumeral joint related to shoulder instability. Ample reference will be given as to why identification of abnormalities, whether normal or pathologic, is important to the surgeon facing a treatment decision.

Inferior glenohumeral ligament (IGHL) complex: anatomy, injuries, imaging features, and treatment options

The inferior glenohumeral ligament (IGHL) complex is comprised of three components supporting the inferior aspect of the shoulder. It consists of an anterior band, a posterior band, and an interposed axillary pouch. Injuries to the IGHL complex have a unifying clinical history of traumatic shoulder injury, which are often sports or fall-related, with the biomechanical mechanism, positioning of the arm, and individual patient factors determining the specific component of the ligamentous complex that is injured, the location of the injury of those components, and the degree of bone involvement. Several acronyms are employed to characterize these features, specifying whether there is involvement of a portion of the anterior band, posterior band, or midsubstance, and if there is avulsion from the humeral attachment, glenoid attachment, or both. Imaging recommendations for the evaluation of the IGHL complex include magnetic resonance imaging (MRI), and injuries to this complex are best visualized with magnetic resonance arthrography. Additionally, a brief description of clinical management of inferior glenohumeral ligament injuries is included.

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.

Quantitative analysis of attachment of the labrum to the glenoid fossa: a cadaveric study

PURPOSE

This study investigated the direct and continuous attachment of the labrum to the glenoid fossa, including the fibrocartilaginous tissue, using image-analysis software and histology.

METHODS

Twenty-six cadaveric shoulders (11 male, 15 female; mean age 80.1 years; age range 36-103 years) were used. The glenoid of each specimen was divided into six pie-slice-shaped pieces from the center perpendicular to the articular surface by radial incisions at the 2, 4, 6, 8, 10, and 12 o'clock positions. The general distribution of the labrum, including the fibrocartilage, was assessed in hematoxylin and eosin-, Safranin O- and Azan-Mallory-stained sections. The continuous length of attachment of the labrum to the glenoid was measured using image-analysis software. The width of attachment to the articular surface of the glenoid was assessed in each position.

RESULTS

The labrum attached to both the articular surface and the neck of the glenoid in all shoulders (100 %) in the 4 and 6 o'clock positions. The mean length of the entire attachment to the glenoid was 4.6 mm (range 3.2-6.1 mm). The width of attachment from the bony edge of the glenoid to the edge of the labrum on the articular surface ranged from 0 to 4.3 mm. The length of the entire attachment of the labrum was shortest in the 2 o'clock position (p = 0.229). Additionally, the length of the entire attachment of the labrum was longest in the 4 o'clock position. The width of attachment to the articular surface of the glenoid was greatest in the 4 o'clock position (p < 0.01).

CONCLUSION

In the 4 and 6 o'clock positions, the labrum attached to both the articular surface and neck of the glenoid in all of the shoulders (100 %). The length of the entire attachment to the labrum, including the fibrocartilage, was shortest in the 2 o'clock position. The width of attachment to the articular surface of the glenoid was greatest in the 4 o'clock position (p < 0.01).