Anterior Band Of The Inferior Glenohumeral Ligament Research Articles

Poster 107: Biomechanical Effect of “AIGHL Reconstruction” for Bankart Lesion in Thrower’s Shoulder: A Novel Surgical Treatment to Maintain Maximum Shoulder External Rotation Angle after Surgery

Objectives: For anterior shoulder instability, antero-inferior labral repair (Bankart repair) is a reliable surgery to prevent shoulder dislocation. However, in biomechanical and clinical studies, maximum shoulder external rotation angle is reported to be decreased by about 10 degrees due to shortening of the anterior band of the inferior glenohumeral ligament (AIGHL) length after Bankart repair. For overhead throwing athletes, the 10 degrees reduction in shoulder external rotation makes it difficult to return to the previous performance level, although it does not affect daily activity. To prevent shortening of the AIGHL length, an AIGHL reconstruction was developed using fascia lata graft. Preliminary clinical results in overhead throwing athletes showed that a throwing program could start with complete restoration of maximum shoulder external rotation angle 3 months after AIGHL reconstruction. In this study the effect of AIGHL reconstruction on shoulder external rotation and anterior stability for simulated Bankart lesion in a cadaveric model of a thrower’s shoulder was evaluated (Fig. 1). Methods: Eight cadaveric shoulders were tested at 60° of glenohumeral abduction (90° of shoulder abduction) to simulate throwing motion. Glenohumeral translations at 60° and 90° of external rotation, maximum humeral rotational range of motion, and humeral head shift were measured using goniometer and MicroScribe 3D-digitizer. Each specimen was subjected to five experimental stages: (1) intact condition; (2) simulation of thrower’s shoulder by anterior capsular stretching based on previously reported method; (3) creation of Bankart lesion (AIGHL and the labrum were detached at glenoid side); (4) Bankart repair using three suture anchors; and (5) AIGHL reconstruction using allograft of fascia lata. In the AIGHL reconstruction, allograft was patched between the detached AIGHL and glenoid at maximum shoulder external rotation position to restore the original AIGHL length (Fig. 2). For statistical analysis, linear mixed-effects model and Tukey’s post-hoc analysis were used. Results: After 20% stretching, shoulder external rotation and anterior translation were significantly increased (intact 128.3° and 2.8mm, thrower’s shoulder 141.9° and 7.3mm, p<0.001). Creation of Bankart lesion significantly increased anterior translation (8.3mm) compared with intact condition (p=0.021). Bankart repair completely restored anterior translation (3.0mm) to intact level; however, maximum shoulder external rotation angle after Bankart repair (134.8°) was significantly less than that in thrower’s shoulder (p=0.009). AIGHL reconstruction completely restored anterior translation (6.5mm) to thrower’s shoulder without decreasing maximum shoulder external rotation angle (144.4°) compared with thrower’s shoulder (Fig. 3 & 4). At maximum humeral external rotation, the humeral head was significantly shifted superiorly after creation of Bankart lesion compared with intact condition(p=0.005). After Bankart repair, the humeral head was significantly shifted inferiorly from the Bankart lesion (p=0.003) and was significantly inferior relative to the position after AIGHL reconstruction (p=0.007). Conclusions: While Bankart repair completely restored anterior translation to the intact level (tighter than thrower’s shoulder), AIGHL reconstruction completely restored to the thrower’s level. Furthermore, maximum shoulder external rotation angle was maintained after AIGHL reconstruction although Bankart repair decreased external rotation significantly. Therefore, AIGHL reconstruction can be a useful surgical option for Bankart lesion in overhead throwing athletes to restore anterior stability while maintaining maximum shoulder external rotation angle after surgery.

Direction of non-recoverable strain in the glenohumeral capsule following multiple anterior dislocations: Implications for anatomic Bankart repair.

The study aimed to analyze the direction of non-recoverable strain and determine the optimal direction for anatomic capsular plication within four sub-regions of the inferior glenohumeral capsule following multiple dislocations. Seven fresh-frozen cadaveric shoulders were dissected. A grid of strain markers was affixed to the inferior glenohumeral capsule. Each joint was mounted in a 6-degree-of-freedom robotic testing system and repeatedly dislocated in the anterior direction 10 times at 60° of abduction and 60° of external rotation of the glenohumeral joint. The 3D positions of the strain markers were compared before and after dislocations to define the non-recoverable strain. The strain map was divided into four sub-regions. The angles of deviation between each maximum principle strain vector and the anterior band of the inferior glenohumeral ligament (AB-IGHL) or posterior band of the IGHL (PB-IGHL) for the anterior and posterior regions of the capsule were determined. The mean direction of all strain vectors in each sub-region was categorized. The direction of the non-recoverable strain in the anterior-band and anterior-axillary-pouch sub-regions was categorized as parallel to the AB-IGHL, whereas the posterior-axillary-pouch and posterior-band sub-regions were mostly perpendicular to the PB-IGHL. Clinical Significance: Plication of the anteroinferior capsule parallel to the AB-IGHL may be preferred during arthroscopic Bankart repair to restore anatomy; posteroinferior capsular plication may also be necessary and best performed perpendicular to the PB-IGHL.The direction of the capsular injury remains the same irrespective of the number of dislocations.This study provides the scientific and quantitative rationale for an anatomic approach to capsular plication.

Effect of patient positioning in axillary nerve safety during arthroscopic inferior glenohumeral ligament plication.

To evaluate the risk of injuring the axillary nerve during an inferior glenohumeral ligament (IGHL) plication and finding out whether shoulder position (either beach chair position or lateral decubitus position) has any effect in this risk. The axillary nerve (AN) was identified through a 3-cm posterior incision in 12 cadaveric shoulders. Under arthroscopic visualization, a curved indirect suture-passing device was placed through the posterior and anterior bands of the IGHL. The distances between the device and the AN were measured with the shoulder specimen placed at simulated lateral decubitus position and beach chair position. There were no cases of nerve injury nor the suture-passing device came closer than 10mm to the nerve. There was an increase in the injury risk to the AN when inserting the device at the posterior band of the IGHL in the beach chair position [median 13mm (range 10-21mm)] compared to the risk in the lateral decubitus position [22.5mm (20-26mm), significant differences, p<0.001]. When the device was inserted at the anterior band of the IGHL, there were no significant differences (n.s.) [lateral decubitus position: 18mm (14-24mm) vs. 16mm (13-18mm)]. When comparing differences between bands, there were no differences in the beach chair position, but the risk was lower for the posterior band in the lateral decubitus position (p<0.001). During plication of the posterior band of the IGHL, the risk is higher if the procedure is performed in the beach chair position. The posterior plication is safer than the anterior plication in lateral decubitus position. This study helps the surgeon to better understand the proximity of the nerve to the IGHL and to highlight that the risk of nerve injury during capsular plication might be reduced in the lateral decubitus position.

Effect of Bankart repair on the loss of range of motion and the instability of the shoulder joint for recurrent anterior shoulder dislocation

Bankart repair postoperative complications include loss of shoulder motion and shoulder instability. The primary reason that postoperative complications develop may be excessive imbrication of the anterior band of the inferior glenohumeral ligament (AIGHL) or inadequate repair position. The purpose of this study was to quantitatively evaluate the influence of inadequate repair by computer simulation for a normal shoulder joint. Magnetic resonance images of 10 normal shoulder joints were acquired for 7 positions every 30° from the maximum internal rotation to the maximum external rotation with the arm abducted at 90°. The shortest 3-dimensional path of the AIGHL in each rotational orientation was calculated. We used computer simulations to anticipate the loss of motion and instability by changing the AIGHL length and insertion sites on the glenoid. The AIGHL length measured 50 ± 5 mm at the maximum external shoulder rotation. AIGHL shortening by 3, 6, and 9 mm made the angle of maximum external rotation 80°, 68°, and 54°, respectively. A superior deviation of 3, 6, and 9 mm on the glenoid insertion resulted in a maximum external rotation angle of 85°, 79°, and 77°. An inferior deviation of 3, 6, and 9 mm produced humeral head translation of 1.7, 2.9, and 3.6 mm. Simulation of both excessive imbrication and deviation of the insertion position led to quantitative prediction of the resulting loss of motion and instability. These findings will be useful for anticipating complications after Bankart repair. Basic science study, computer modeling, imaging.

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.

Structural and mechanical properties of the glenohumeral joint posterior capsule

The purpose of this study was to quantify regional variations in material properties of the glenohumeral joint posterior capsule and to compare these data with the anterior band of the inferior glenohumeral ligament (AB-IGHL). Mechanical properties were determined for individual bands of the AB-IGHL, superior posterior capsule (SUP-PC), middle posterior capsule (MID-PC), and inferior posterior capsule (INF-PC). Significant differences in tissue thickness were found among the 3 posterior capsular regions and the AB-IGHL. The AB-IGHL was thicker than the MID-PC (P=.03) and INF-PC (P=.01), and the SUP-PC was thicker than the INF-PC (P=.02). Except for significant differences in failure strains, material properties were not significantly different among the 4 tissue regions. There were no significant differences between tissue bands in modulus (P=.2), maximum stress (P=.46), or strain energy density (P=.62). Specimens failed primarily near the glenoid insertion (75%), with 4 specimens failing at the humeral insertion and 2 others failing in the tissue's mid substance.

Stress and strain in the anterior band of the inferior glenohumeral ligament during a simulated clinical examination

The objective of this research was to predict, with a finite-element model, the stress and strain fields in the anterior band of the inferior glenohumeral ligament (AB-IGHL) during application of an anterior load with the humerus abducted. The stress and strain in the AB-IGHL were determined during a simulated simple translation test of a single intact shoulder. A 6-degree-of-freedom magnetic tracking system was used to measure the kinematics of the humerus with respect to the scapula. A clinician applied an anterior load to the humerus until a manual maximum was achieved at 60 degrees of glenohumeral abduction and 0 degrees of flexion/extension and external rotation. For the computational analysis, the experimentally measured joint kinematics were used to prescribe the motion of the humerus with respect to the scapula, whereas the material properties of the AB-IGHL were based on published experimental data. The geometry of the AB-IGHL, humerus, and scapula was acquired by use of a volumetric computed tomography scan, which was used to define the reference configuration of the AB-IGHL. Strains reached 12% along the inferior edge and 15% near the scapular insertion site at the position of maximum anterior translation. During this motion, the AB-IGHL wrapped around the humerus and transferred load to the bone via contact. Predicted values for von Mises stress in the ligament reached 4.3 MPa at the point of contact with the humeral head and 6.4 MPa near the scapular insertion site. A comparison of these results to the literature suggests that the computational approach provided reasonable predictions of fiber strain in the AB-IGHL when specimen-specific geometry and kinematics with average material properties were used. The complex stress and strain distribution throughout the AB-IGHL suggests that the continuous nature of the glenohumeral capsule should be considered in biomechanical analyses. In the future, this combined experimental and computational approach will be used for subject-specific studies of capsular function and could provide quantitative data to help surgeons improve methods for the diagnosis and treatment of glenohumeral instability.

Normal variations of the glenohumeral ligament complex: an anatomic study for arthroscopic bankart repair

Purpose The purpose of this study was to evaluate the prevalence and morphologic characteristics of normal variations in the glenohumeral ligament complex (GHLC). Type of study Anatomic study in cadavers. Methods We investigated 84 cadaver shoulders and recorded visualization of the superior glenohumeral ligament (SGHL), middle glenohumeral ligament (MGHL), and anterior band of the inferior glenohumeral ligament (AIGHL). In cases with an AIGHL, we noted the location of its origin with respect to the anterior glenoid in terms of a clock face as in a right shoulder. If an MGHL was present, the site of its glenoid attachment was recorded. The presence of a cord-like MGHL, the Buford complex, and a sublabral foramen was also investigated. Results Of these, 79 (94.1%) manifested an SGHL, 53 (63.1%) an MGHL, and 76 (90.5%) an AIGHL. The AIGHL originated in an area located between the 2- and 5-o’clock position; in 11 (14.5%), the origin was at the 2-o’clock position; in 49 (64.5%) at the 3-o’clock position; in 11 (14.5%), the 4-o’clock position; and in 5 (6.5%) at the 5-o’clock position. Two common variations in the attachment of the MGHL were seen; 30 of 53 MGHL (56.6%) originated from the labrum separate from the origin of the SGHL, and 23 (43.4%) from the labrum at the origin of the SGHL. Of the 84 specimens, 15 (17.9%) manifested a cord-like MGHL, and one (1.2%) the Buford complex. None of the specimens had a sublabral foramen, a finding that requires further investigation. Conclusions Our results suggest that the Buford complex is a rare variant of the GHLC, and the cord-like MGHL appears to be a relatively common normal variant. Clinical relevance The present study provides useful information concerning normal variations of the GHLC to arthroscopists considering Bankart repair.

Labral-Ligamentous Complex of the Shoulder. Evaluation with double oblique axial MR arthrography

To assess the ability of double oblique axial (DOA) MR arthrography in evaluating labral-ligamentous complex compared with conventional axial (CA) MR arthrography. MR arthrography of 51 shoulders, subsequently examined with arthroscopy, were retrospectively reviewed. DOA imaging was performed in all 51 shoulders and both DOA and CA imaging in 37 using a 1.5 T unit with gradient recalled-echo T2*-weighted sequences. DOA imaging was performed using perpendicular planes to the long axis of the glenoid fossa obtained by an oblique sagittal scout image. We compared the ability of DOA with that of CA MR arthrography to assess labral injuries and to demonstrate the whole length of the anterior band of the inferior glenohumeral ligament (AIGHL), which were shown to be intact by arthroscopy. For anterior labral injuries, sensitivity and specificity were 87% and 93% with CA, and 94% and 100% with DOA imaging, respectively. For posterior labral injuries, sensitivity and specificity were 47% and 100% with CA, and 79% and 96% with DOA imaging, respectively. There were no statistically significant differences between CA and DOA images, except for the ability to diagnose posterior labral injuries, where DOA imaging had a significant superior sensitivity (p=0.0327). DOA images also demonstrated the whole length of the intact AIGHL in 10 of 11 shoulders, while CA imaging showed this in only 3 of 11. DOA imaging was equal or better than CA imaging for evaluating the labral-ligamentous complex.

Labral-ligamentous complex of the shoulder. Evaluation with double oblique axial MR arthrography.

To assess the ability of double oblique axial (DOA) MR arthrography in evaluating labral-ligamentous complex compared with conventional axial (CA) MR arthrography. MR arthrography of 51 shoulders, subsequently examined with arthroscopy, were retrospectively reviewed. DOA imaging was performed in all 51 shoulders and both DOA and CA imaging in 37 using a 1.5 T unit with gradient recalled-echo T2*-weighted sequences. DOA imaging was performed using perpendicular planes to the long axis of the glenoid fossa obtained by an oblique sagittal scout image. We compared the ability of DOA with that of CA MR arthrography to assess labral injuries and to demonstrate the whole length of the anterior band of the inferior glenohumeral ligament (AIGHL), which were shown to be intact by arthroscopy. For anterior labral injuries, sensitivity and specificity were 87% and 93% with CA, and 94% and 100% with DOA imaging, respectively. For posterior labral injuries, sensitivity and specificity were 47% and 100% with CA, and 79% and 96% with DOA imaging, respectively. There were no statistically significant differences between CA and DOA images, except for the ability to diagnose posterior labral injuries, where DOA imaging had a significant superior sensitivity (p=0.0327). DOA images also demonstrated the whole length of the intact AIGHL in 10 of 11 shoulders, while CA imaging showed this in only 3 of 11. DOA imaging was equal or better than CA imaging for evaluating the labral-ligamentous complex.