Multidirectional Instability: Natural History and Evaluation

Multidirectional instability of the shoulder: a systematic review with a novel classification

Purpose

A variety of instabilities are grouped under multidirectional instability (MDI) of the shoulder. This makes understanding its diagnostic process, presentation and treatment difficult due to lack of evidence-based consensus. This review aims to propose a novel classification for subtypes of MDI.

Methods

A systematic search was performed on PubMed Medline and Embase. A combination of the following 'MeSH' and 'non-MesH' search terms were used: (1) Glenohumeral joint[tiab] OR Glenohumeral[tiab] OR Shoulder[tiab] OR Shoulder joint[tiab] OR Shoulder[MeSH] OR Shoulder joint[MeSH], (2) Multidirectional[tiab], (3) Instability[tiab] OR Joint instability[MeSH]. Sixty-eight publications which met our criteria were included.

Results

There was a high degree of heterogeneity in the definition of MDI. Thirty-one studies (46%) included a trauma etiology in the definition, while 23 studies (34%) did not. Twenty-five studies (37%) excluded patients with labral or bony injuries. Only 15 (22%) studies defined MDI as a global instability (instability in all directions), while 28 (41%) studies considered MDI to be instability in two directions, of which one had to include the inferior direction. Six (9%) studies included the presence of global ligamentous laxity as part of the definition. To improve scientific accuracy, the authors propose a novel AB classification which considers traumatic etiology and the presence of hyperlaxity when subdividing MDI.

Conclusion

MDI is defined as symptomatic instability of the shoulder joint in two or more directions. A comprehensive classification system that considers predisposing trauma and the presence of hyperlaxity can provide a more precise assessment of the various existing subtypes of MDI.

Level of Evidence

III.

Multidirectional instability of the shoulder: surgical techniques and clinical outcome

Multidirectional instability of the shoulder has a complex pathoanatomy. It is characterized by a redundant glenohumeral capsule and increased joint volume. Subtle clinical presentation, unclear trauma history and multifactorial etiology poseses a great challenge for orthopedic surgeons in terms of diagnosis. Generally accepted therapeutic approach is conservative and the majority of patients achieve good results with rehabilitation. In patients who are symptomatic despite appropriate rehabilitation, surgical intervention may be considered. Good results have been obtained with open inferior capsular surgery, which has historically been performed in these patients. In recent years, advanced arthroscopic techniques have taken place in this field, and similar results compared to open surgery have been obtained with the less-invasive arthroscopic capsular plication procedure.

Advances in the Non-Operative Management of Multidirectional Instability of the Glenohumeral Joint

Multidirectional instability (MDI) of the glenohumeral joint refers to symptomatic subluxations or dislocations in more than one direction. The aetiology of MDI is multifactorial, which makes the classification of this condition challenging. A shoulder rehabilitation program is the initial recommended treatment for MDI, however available rehabilitation programs have varying levels of evidence to support their effectiveness. In 2016, we published the details of an evidence-based program for MDI that has been evaluated for efficacy in two single-group studies and a randomised controlled trial. In 2017, we published a clinical commentary on the aetiology, classification, and treatment of this condition. The aim of this paper is to provide an update on the components of these publications with a particular focus on new advances in the non-operative management of this condition.

[Rebalancing theory of shoulder stability mechanism for the diseases related to the shoulder instability and dysfunction of motion]

Objective

To introduce a new theory of shoulder stability mechanism, rebalancing theory, and clinical application of this new theory for the shoulder instability and dysfunction of motion.

Methods

Through extensive review of the literature related to shoulder instability and dysfunction of the motion in recent years, combined with our clinical practice experience, the internal relation between passive stability mechanism and dynamic stability mechanism were summarized.

Results

Rebalancing theory of shoulder stability mechanism is addressed, namely, when the shoulder stability mechanism is destructive, the stability of the shoulder can be restored by the rebalance between dynamic stability mechanism and passive stability mechanism. When dynamic stability is out of balance, dynamic stability can be restored by rebalancing the different parts of dynamic stability mechanism or to strengthen the passive stability mechanism. When passive stability mechanism is out of balance, passive stability can be restored by rebalancing the soft tissue and bone of the shoulder.

Conclusion

Rebalancing theory of shoulder stability mechanism could make a understanding the occurrence, development, and prognosis of shoulder instability and dysfunction from a comprehensive and dynamic view and guide the treatment effectively.

Scapular Dyskinesis, Shoulder Joint Position Sense, and Functional Level After Arthroscopic Bankart Repair

Background:

Scapular kinesia is an important component of glenohumeral rhythm and shoulder stability. No studies have evaluated scapular dyskinesis and its relationship to shoulder proprioception in patients who have undergone arthroscopic Bankart repair (ABR).

Purpose:

To investigate scapular dyskinesis, proprioception, and functional level after ABR.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This study included 13 male patients who underwent ABR (ABR group; mean age, 30 years; range, 24-36 years) and 13 sex- and age-matched healthy individuals (control group). The age, height, weight, and dominant side of all participants were collected. Scapular dyskinesis was evaluated using the lateral scapular slide test and the scapular dyskinesis test; proprioception was measured by the active angle reproduction test using a smartphone goniometer application, and functional level was assessed using the upper-quarter Y-balance test for dynamic stability as well as the Rowe score and Walch-Duplay score for quality of life and return to activities of daily living.

Results:

The presence of static scapular dyskinesis in the neutral position, at 45° of abduction, and at 90° of abduction as well as the presence of dynamic scapular dyskinesis was higher in the ABR group compared with the control group (P ≤ .04 for all). Shoulder joint position sense (absolute error) at 40° and 100° of shoulder elevation and shoulder functional level according to the Rowe score were worse in the ABR patients compared with the healthy controls (P ≤ .02 for all). Dynamic scapular dyskinesis was negatively related to shoulder joint position sense at 40° of shoulder elevation (r = –0.64; P = .01). Static scapular movement as measured on the lateral scapular slide test was moderately related to the Rowe score (r = 0.58; P = .03).

Conclusion:

Scapular kinematics and proprioception should be evaluated after ABR. Treatment approaches to improve scapular control and proprioceptive sense should be included in the rehabilitation program for patients after ABR.

Electromyographic muscle activity and three-dimensional scapular kinematics in patients with multidirectional shoulder instability

OBJECTIVE

To investigate differences in EMG muscle activity and scapular kinematics during elevation in the scapular plane between healthy controls, participants with multidirectional shoulder laxity (MDL), and patients with multidirectional shoulder instability (MDI) who are diagnosed with hypermobile Ehlers-Danlos syndrome (hEDS) or Hypermobility Spectrum Disorder (HSD).

METHODS

Twenty-seven women with hEDS/HSD and MDI, 27 female healthy control subjects, and 28 female subjects with MDL participated in this study. Scapular 3D kinematic data were obtained using 8 Oqus Qualisys cameras. Simultaneously, surface electromyography (EMG) was used to measure muscle activity of the upper, middle, and lower trapezius, infraspinatus, latissimus dorsi, serratus anterior, posterior deltoid, and pectoralis major during arm elevation in the scapular plane. Group differences were assessed using statistical parametric mapping.

RESULTS

Regarding scapular kinematics, significantly less upward rotation was observed in hEDS/HSD patients with MDI compared to both healthy controls and MDL subjects. Significantly less posterior tilt was seen in hEDS/HSD patients compared to MDL subjects. Furthermore, significantly higher EMG activity of the infraspinatus, middle trapezius, and posterior deltoid was found in hEDS/HSD patients with MDI.

CONCLUSION

hEDS/HSD patients with MDI demonstrate altered scapular kinematics and increased EMG muscle activity compared to subjects without MDI. These findings could serve as stepping stone for future research regarding treatment strategies in patients belonging to the hypermobility spectrum.

Scapular Dyskinesis: From Basic Science to Ultimate Treatment

Background: This study intends to summarize the causes, clinical examination, and treatments of scapular dyskinesis (SD) and to briefly investigate whether alteration can be managed by a precision rehabilitation protocol planned on the basis of features derived from clinical tests. Methods: We performed a comprehensive search of PubMed, Cochrane, CINAHL and EMBASE databases using various combinations of the keywords “Rotator cuff”, “Scapula”, “Scapular Dyskinesis”, “Shoulder”, “Biomechanics” and “Arthroscopy”. Results: SD incidence is growing in patients with shoulder pathologies, even if it is not a specific injury or directly related to a particular injury. SD can be caused by multiple factors or can be the trigger of shoulder-degenerative pathologies. In both cases, SD results in a protracted scapula with the arm at rest or in motion. Conclusions: A clinical evaluation of altered shoulder kinematics is still complicated. Limitations in observing scapular motion are mainly related to the anatomical position and function of the scapula itself and the absence of a tool for quantitative SD clinical assessment. High-quality clinical trials are needed to establish whether there is a possible correlation between SD patterns and the specific findings of shoulder pathologies with altered scapular kinematics.