The role of bone in glenohumeral stability

Abstract

Shoulder stability depends on several factors, either anatomical or functional. Anatomical factors can be further subclassified under soft tissue (shoulder capsule, glenoid rim, glenohumeral ligaments etc) and bony structures (glenoid cavity and humeral head).Normal glenohumeral stability is maintained through factors mostly pertaining to the scapular side: glenoid version, depth and inclination, along with scapular dynamic positioning, can potentially cause decreased stability depending on the direction of said variables in the different planes. No significant factors in normal humeral anatomy seem to play a tangible role in affecting glenohumeral stability.When the glenohumeral joint suffers an episode of acute dislocation, either anterior (more frequent) or posterior, bony lesions often develop on both sides: a compression fracture of the humeral head (or Hill–Sachs lesion) and a bone loss of the glenoid rim. Interaction of such lesions can determine ‘re-engagement’ and recurrence.The concept of ‘glenoid track’ can help quantify an increased risk of recurrence: when the Hill–Sachs lesion engages the anterior glenoid rim, it is defined as ‘off-track’; if it does not, it is an ‘on-track’ lesion. The position of the Hill–Sachs lesion and the percentage of glenoid bone loss are critical factors in determining the likelihood of recurrent instability and in managing treatment.In terms of posterior glenohumeral instability, the ‘gamma angle concept’ can help ascertain which lesions are prone to recurrence based on the sum of specific angles and millimetres of posterior glenoid bone loss, in a similar fashion to what happens in anterior shoulder instability.Cite this article: EFORT Open Rev 2018;3:632-640. DOI: 10.1302/2058-5241.3.180028

Correction to: Qualitative and quantitative analysis of glenoid bone stock and glenoid version: inter-reader analysis and correlation with rotator cuff tendinopathy and atrophy in patients with shoulder osteoarthritis

“…Despite prior studies [18,19] suggesting that there is no relationship between glenoid version and humeral head subluxation in patients with posterior shoulder instability, we found increasing anteversion related to decreasing HSI (p < 0.0001). This finding is supported by other studies demonstrating the relationship between glenoid anteversion and frank anterior dislocation of the shoulder [20,21]. In addition, we found anterior bone loss correlating to decreased HSI (p < 0.0001).…”

“…As such, any anterior or posterior bone loss alters the concavity of the glenoid cavity and thus, static destabilization, especially those decreasing the depth and curvature, increases the likelihood of decentering of the humeral head. Indeed, multiple reports have been made of the impact of anterior bone loss and frank anterior shoulder dislocation [20,21]. Our findings support these prior findings in adding additional evidence that it is glenoid bone loss that correlates most directly with pathologic humeral head subluxation, both anteriorly and posteriorly.…”

The utilization of computer planning and 3D-printed guide in the surgical management of a reverse Hill-Sachs lesion

“…The present case involved an anterior-superior depression on the surface of the humeral head; this manifestation is known as a reverse Hill-Sachs lesion and is present in 86% of posterior dislocations. 8 …”

Analysis of roentgenologic parameters of the articular process of the scapula in children with instability of the shoulder joint

“…В зависимости от генеза возникновения выделяют следующие причины нестабильности в плечевом суставе у детей: диспластический характер фиброзной губы суставного отростка лопатки по гипопластическому типу при нестабильности атравматического генеза; повреждение мягкотканных стабилизаторов плечевого сустава, таких как связки, суставная губа, капсула плечевого сустава, сухожилие бицепса при нестабильности травматического генеза [7][8][9].…”

“…В норме он колеблется от 2° антеверcии до 9° ретроверcии [4,13]. Данные об отклонении гленоида кзади указывают на это как на важный анатомический фактор, предрасполагающий к развитию задней нестабильности плечевого сустава [7][8][9].…”