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.

Predictive Value of Gagey's Hyperabduction Test in Identifying Inferior Glenohumeral Ligament Lesions

INTRODUCTION

Clinical tests that can identify inferior glenohumeral ligament (IGHL) complex injuries are indispensable for the diagnosis of shoulder instability. Gagey's hyperabduction test has been developed to diagnose IGHL hyperlaxity, however, it is unclear whether the test is able to accurately diagnose an IGHL lesion. The aim of this study was to (1) determine the diagnostic performance of the Gagey test in identifying an IGHL lesion and (2) determine if a positive Gagey test is more predictive for an anterior or posterior IGHL lesion thanks to the heatmapping of the lesions. It was hypothesized that a Gagey test can accurately predict IGHL lesions, but would not be able to distinguish between anterior and inferior IGHL lesions.

METHODS

A retrospective diagnostic accuracy study was conducted including all consecutive patients who underwent glenoid labral repair between January 2005 and September 2021 with a documented Gagey test prior to surgery. Using arthroscopic findings as a reference standard, the diagnostic performance characteristics of the Gagey test for each type of IGHL lesion (anterior, posterior and combined) were calculated and labral heatmapping was used to depict its localisation.

RESULTS

A total of 167 patients were included, with a mean age of 29 ± 10 years. The sensitivity, specificity and accuracy of the Gagey test on determining an IGHL lesion were 46%, 38% and 46%, respectively. The positive and negative predictive values were 88% and 7%, respectively. Heatmapping of the labral lesions demonstrated that a positive Gagey test was most predictive of anterior IGHL and axillary pouch tears and non-predictive of posterior IGHL lesions.

DISCUSSION

The Gagey test demonstrated a low sensitivity and specificity to identify an IGHL lesion and therefore the hypothesis could not be confirmed. However, the Gagey test has a high positive predictive value to diagnose anterior IGHL lesions. Further prospective research with a more evenly distribution of lesions is needed to investigate the clinical value of the Gagey test to identify these lesions. Based on this data, the Gagey test seems especially important to support the results of other clinical tests such as the apprehension, relocation and surprise tests.

LEVEL OF EVIDENCE

III, Retrospective Case-Control study.

Mapping of the Inferior Glenohumeral Ligament for Suture Pullout Strength: A Biomechanical Analysis

Background

Suture pullout during rehabilitation may result in loss of tension in the inferior glenohumeral ligament (IGHL) and contribute to recurrent instability after capsular plication, performed with or without labral repair. To date, the suture pullout strength in the IGHL is not well-documented. This may contribute to recurrent instability.

Purpose/Hypothesis

A cadaveric biomechanical study was designed to investigate the suture pullout strength of sutures in the IGHL. We hypothesized that there would be no significant variability of suture pullout strength between specimens and zones. Additionally, we sought to determine the impact of early mobilization on sutures in the IGHL at time zero. We hypothesized that capsular plication sutures would fail under low load.

Study Design

Descriptive laboratory study.

Methods

Seven fresh-frozen cadaveric shoulders were dissected to isolate the IGHL complex, which was then divided into 18 zones. Sutures in these zones were attached to a linear actuator, and the resistance to suture pullout was recorded. A suture pullout strength map of the IGHL was constructed. These loads were used to calculate the load applied at the hand that would initiate suture pullout in the IGHL.

Results

Mean suture pullout strength for all specimens was 61.6 ± 26.1 N. The maximum load found to cause suture pullout through tissue was found to be low, regardless of zone of the IGHL. Calculations suggest that an external rotation force applied to the hand of only 9.6 N may be sufficient to tear capsular sutures at time zero.

Conclusion

This study did not provide clear evidence of desirable locations for fixation in the IGHL. However, given the low magnitude of failure loads, the results suggest the timetable for initiation of range-of-motion exercises should be reconsidered to prevent suture pullout through the IGHL.

Clinical Relevance

From this biomechanical study, the magnitude of force required to cause suture pullout through the IGHL is met or surpassed by normal postoperative early range-of-motion protocols.

Axillary Nerve Position in Humeral Avulsions of the Glenohumeral Ligament

Background

The axillary nerve is at risk during repair of a humeral avulsion of the glenohumeral ligament (HAGL).

Purpose

To measure the distance between the axillary nerve and the free edge of a HAGL lesion on preoperative magnetic resonance imaging (MRI) and compare these findings to the actual intraoperative distance measured during open HAGL repair.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 25 patients with anterior instability were diagnosed as having a HAGL lesion on MRI and proceeded to open repair. The proximity of the axillary nerve to the free edge of the HAGL lesion was measured intraoperatively at the 6-o'clock position relative to the glenoid face. Preoperative MRI was then used to measure the distance between the axillary nerve and the free edge of the HAGL lesion at the same position. Distances were compared using paired t tests and Bland-Altman analyses.

Results

The axillary nerve lay, on average, 5.60 ± 2.51 mm from the free edge of the HAGL lesion at the 6-o'clock position on preoperative MRI, while the mean actual intraoperative distance during open HAGL repair was 4.84 ± 2.56 mm, although this difference was not significant (P = .154). In 52% (13/25) of patients, the actual intraoperative distance of the axillary nerve to the free edge of the HAGL lesion was overestimated by preoperative MRI. In 36% (9/25), this overestimation of distance was greater than 2 mm.

Conclusion

The observed overestimations, although not significant in this study, suggest a smaller safety margin than might be expected and hence a substantially higher risk for potential damage. We recommend that shoulder surgeons exercise caution in placing capsular sutures in the lateral edge when contemplating arthroscopic repair of HAGL lesions, as the proximity of the nerve to the free edge of the HAGL tear is small enough to be injured by arthroscopic suture-passing instruments.