Abstract
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
Introduction
Multidirectional instability (MDI) of the shoulder is a complex and a rare condition. The incidence of MDI is thought to be low, although the exact incidence is difficult to establish due to the variations in diagnostic criteria of MDI over the years. Neer and Foster (1) published an early description of MDI in 1980, which served to highlight MDIs as a different entity from traumatic structural unidirectional instabilities. The key diagnostic characteristic of MDI was described as shoulder instability in two or more directions (1). Since then, however, there have been differences in the literature regarding the exact definition and classification of MDI. There are several reasons for the discrepancies in definition. MDI can present with a wide variety of symptoms, ranging from isolated shoulder pain on movement to frank multidirectional instability (2). In addition, some patients may be able to sublux or dislocate the glenohumeral joint voluntarily. These patients confound the clinical diagnosis as they are often asymptomatic and yet able to demonstrate significant subluxation or dislocation (3). The decision to include these patients within the MDI diagnosis is currently controversial as the literature has shown that voluntary dislocators may not respond as well to surgical intervention as non-voluntary ones.
It can also be challenging to determine a clear definition of MDI due to its intuitive overlap with generalized ligamentous laxity or hyperlaxity. While there can be an association between MDI and generalized ligamentous laxity (4), these terms should not be used interchangeably. Generalized ligamentous laxity can be physiological or associated with connective tissue disorders such as Marfan syndrome, Ehlers–Danlos syndrome, and benign joint hypermobility syndrome (5). These patients can be identified clinically utilizing Beighton’s criteria or if they exhibit external rotation ≥85° (6, 7). If these patients are asymptomatic, they should not be considered to have MDI, despite the apparent laxity of the joint in two or more directions. There is now an evolving distinction between asymptomatic generalized ligamentous laxity, unilateral instability on the background of generalized ligamentous laxity, and MDI (4).
Several classifications have been described for MDI, but no particular classification appears to be universally accepted. The instability classification by Rockwood (8) focused on the presence of a traumatic etiology and the volitional aspect of the dislocation. Rockwood grouped traumatic subluxations (without a frank dislocation) as type 1 and traumatic frank dislocations as type 2. MDI patients were grouped into type 3 – voluntary subluxation MDI with no trauma and type 4 – atraumatic involuntary subluxation. Thomas and Matsen (9) classically divided shoulder instability into one of two broad categories: traumatic, unilateral, Bankart, surgery (TUBS) and of atraumatic, multidirectional, bilateral, rehabilitation, inferior capsular shift (AMBRI). While AMBRI patients demonstrated many of the characteristics of an MDI patient, including some degree of laxity of the capsule, the exact definition of an MDI patient was not established. It is worthwhile noting that Thomas and Matsen’s description of the AMBRI group of patients was a conceptual one at the time and not based on published data (9). Gerber and Nyffeler (10) in 2002 were one of the first to include a multidirectional hyperlax subgroup in anterior instability explicitly. Thereafter, in 2010, Kuhn (11) published a new classification system for shoulder instability, termed as the FEDS (frequency, etiology, direction, and severity) classification and intentionally left out MDI in the classification. Kuhn described the concept of MDI as a flawed concept without consensus and opted to focus instead on the primary direction of instability. In addition, the FEDS classification did not include pain as a secondary sign of subtle instability. The variability of these existing classification systems makes it challenging to determine ideal treatment modalities and outcomes. Indeed, McFarland et al. (12) found that variations in criteria for diagnosis of MDI significantly affected the distribution of patients with the diagnosis and that the use of laxity testing resulted in an overestimation of patients with MDI. In addition, Warby et al. (13) performed a systematic review of conservative vs surgical treatment of MDI patients and found a high level of participant heterogeneity. There are thus high levels of heterogeneity currently surrounding the definition and classification of MDI.
This study aimed to conduct a systematic review to identify and highlight the variability of the definition of MDI in the existing literature and to propose a standardized classification to improve future clinical research.
Methods
This systematic review adhered to the principles outlined in the handbook of the Cochrane Collaboration (14) and the established guidelines from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The study protocol, including the search strategy, was registered on PROSPERO (registration number CRD42022293240).
Search strategy
A systematic search was performed on PubMed Medline and Embase from inception until 5 June 2022. A thorough combination of the following 'MeSH' and 'non-MesH' search terms and respective variations were used, with a manual search of the bibliography additionally performed: (i) Glenohumeral joint[tiab] OR Glenohumeral[tiab] OR Shoulder[tiab] OR Shoulder joint[tiab] OR Shoulder[MeSH] OR Shoulder joint[MeSH], (ii) Multidirectional[tiab], (iii) Instability[tiab] OR Joint instability[MeSH].
The following were considered for inclusion: (i) Studies involving human subjects with MDI; (ii) either diagnostic criteria for MDI stated in methodology or characteristics of MDI patients sufficiently described; (iii) at least three patients included in the study; (iv) level of evidence of study ranging 1 to 4. Studies were excluded if they fulfilled the following criteria: review articles, conference abstracts, commentaries, or letters to editors; cadaveric studies (without human subjects); less than three cases reported.
Study selection and data extraction
Two authors (PKAS and HSJ) independently screened and reviewed the studies for inclusion and exclusion in two stages: (i) title and abstract screen and (ii) full-text review of titles to determine study eligibility. Consensus or appeal to senior authors (AL and GN) were performed to resolve any discrepancies.
The primary data of interest were (i) the minimum number of directions to be classified MDI and dominant direction of instability; (ii) diagnostic criteria of MDI, exclusion criteria of the study, and, if separately described, definition of laxity; and (iii) pathological characteristics of MDI. Apart from the aforementioned outcomes, the following data were extracted in a standardized pro forma: study design and level of evidence, patient presentation, presence of pain or functional impairment, exclusion of voluntary dislocators or traumatic onset, and modality of assessment (clinic examination, examination under anesthesia, imaging, and arthroscopy).
Results
Study characteristics and quality assessment
The search strategy yielded 865 studies from two databases, with one additional study added through a manual search of the existing literature bibliography (Fig. 1). This comprised 528 unique studies after the removal of duplicates. Three hundred and eighty-five studies were excluded after title and abstract screening, with 143 studies remaining. We further excluded 75 studies following full-text review: 9 conference abstracts, 10 non-English studies, 3 studies with study types not fulfilling criteria, 15 studies with inaccessible full texts, and 38 studies without clear diagnostic criteria of MDI or clearly stated patient characteristics. A total of 68 studies were included in this systematic review after full-text review.
PRISMA chart of the systematic literature review.
Citation: EFORT Open Reviews 9, 4; 10.1530/EOR-23-0029
Definition of MDI
The definition of MDI is clinical and is derived from both patient history and physical examination. There are two important aspects of patients’ history: pain and symptomatic instability. The studies in this review were analyzed to determine the variability in the definition of a symptomatic MDI patient (Supplementary Table 1, see section on supplementary materials given at the end of this article).
When the history of presenting complaint was analyzed in this review, patients were deemed symptomatic when they presented with either pain, instability and/or subluxation, and/or dislocation in 45 studies (1, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57).
Three studies defined a symptomatic patient as a patient with pain alone (58, 59, 60), while eight studies accepted instability and/or subluxation and/or dislocation alone (61, 62, 63, 64, 65, 66, 67, 68). Twelve studies did not explicitly state what patient history would constitute a symptomatic patient (69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80). Only one study included asymptomatic patients (75).
Twenty-four studies explicitly excluded voluntary dislocators (1, 19, 21, 22, 23, 28, 36, 37, 42, 43, 44, 45, 48, 50, 55, 59, 61, 62, 67, 68, 69, 70, 71, 73), while the rest of the studies did not.
In terms of etiology, 31 studies included both acute trauma and repetitive microtrauma (1, 13, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 28, 30, 35, 42, 43, 44, 49, 53, 56, 57, 58, 59, 62, 69, 70, 77, 78, 80). A single study included only repetitive microtrauma (32), while 33 studies excluded trauma as an etiology in the definition of MDI (19, 27, 29, 31, 33, 37, 41, 45, 47, 48, 50, 51, 52, 54, 55, 60, 63, 64, 65, 66, 67, 76, 79) Thirteen studies did not explicitly mention if trauma as an etiology was included or excluded (34, 36, 38, 39, 40, 46, 61, 68, 71, 72, 73, 74, 75).
Presence of labral or bony lesions
The presence of labral or bony lesions is closely associated with a traumatic etiology. Some of the published literature has chosen to exclude patients with labral or bony lesions. In this review, 25 studies excluded patients if bony lesions such as a SLAP tear, Bankart, or Hill–Sachs lesion was present (1, 26, 27, 31, 32, 33, 35, 36, 39, 40, 45, 54, 55, 58, 61, 63, 64, 65, 66, 67, 72, 73, 74, 76, 77).
Directions of instability
While it is traditionally accepted that MDI requires two or more directions of instability, the studies in this review had differing diagnostic criteria with regard to the number and type of direction of instability.
Fifteen studies (1, 25, 31, 33, 36, 38, 41, 43, 46, 50, 52, 55, 59, 66, 74) defined MDI based on global instability – that is to say, instability in all directions including anterior, posterior, and inferior direction. Twenty-eight studies (13, 16, 19, 21, 23, 24, 26, 27, 29, 30, 34, 35, 42, 44, 51, 53, 54, 56, 57, 62, 63, 65, 67, 69, 70, 75, 76, 80) defined MDI based on two or more directions, one of which had to include the inferior direction. Sixteen studies (17, 18, 20, 22, 28, 37, 45, 47, 48, 49, 60, 61, 71, 73, 77, 78) defined MDI based on two or more directions, where the inferior direction was not mandatory. Five studies (15, 39, 40, 58, 68) defined MDI as long as the inferior direction was present, and four studies (32, 64, 71, 79) were unclear with regard to direction of instability when defining MDI. When determining the presence of inferior instability on physical examination (Supplementary Table 2), all studies used the sulcus sign (Fig. 2), except for four which used inferior apprehension or subluxation (20, 32, 35, 50) and six studies where it was not explicitly mentioned (1, 18, 49, 77, 78, 79).
Clinical photograph showing the presence of the sulcus sign of the left shoulder.
Citation: EFORT Open Reviews 9, 4; 10.1530/EOR-23-0029
Presence of generalized laxity
Six studies included the presence of global ligamentous laxity as part of the definition of MDI (1, 32, 51, 58, 66, 80). Eight studies excluded patients with collagen-based disorders such as Ehlers–Danlos and Marfan syndrome from the MDI diagnosis (19, 30, 42, 44, 47, 54, 55, 71).
Discussion
This systematic review has highlighted that no consistent definition of MDI currently exists. MDI is defined as symptomatic instability in two or more directions. Establishing a standardized classification system is essential so that current assessments and treatment options can be more scientifically precise. In order to improve the accuracy of the classification, definitions of the symptomology commonly associated with MDI must also be established.
Symptomatic patient
In this review, it is apparent that the diagnosis of MDI should only be applied to symptomatic patients. Most studies (45/68, 66.2%) deemed symptomatic patients as those complaining of pain and/or pathological instability (apprehension, subluxation, and/or dislocation). Apprehension is defined as fear of imminent dislocation when placing the arm in abduction and external rotation and should be distinct from mere pain which can be related to inflammation, stiffness, and other shoulder pathologies (81, 82). The authors describe pathological instability as any instability that causes distress to the patient. It has also been previously described as instability that results in a loss of function and symptoms of pain, discomfort, paresthesia, apprehension, and/or fatigue (83, 84). It is important to recognize that pain alone can be a symptom of subtle instability (2). While pain alone as a symptom of instability was once deemed controversial, there is a growing body of evidence to suggest that pain can be the predominant symptom in micro-instability of the shoulder joint (85). During clinical examination, the direction of instability should also be determined with quantitative tests. Anterior and posterior instability can be assessed by utilizing a variety of clinical tests such as the apprehension and Jerk tests (3, 86, 87, 88). For inferior instability, the hyperabduction described by Gagey test can be utilized.90 The authors recommend that the presence of pain and/or pathological instability as defined by apprehension, subluxation, and/or dislocation constitute a symptomatic patient.
Laxity and the unstable painful shoulder
Laxity is a normal, physiologic and asymptomatic finding that corresponds to translation of the humeral head in any direction to the glenoid (89). Laxity can be assessed with the sulcus sign (1), anterior–posterior drawer (87), hyperabduction tests (90), and external rotation of the elbow at the side (6, 89). The two former tests are only qualitative and should not routinely performed. It is thus poignant to note that while the presence of a sulcus sign only diagnoses laxity, it was used by the majority of the studies reviewed in the present article to determine inferior instability.
An unstable painful shoulder can also occur in patients with normal laxity after a traumatic event. However, these patients often present as pain only (as opposed to a sense of instability) during an apprehension maneuver in only one direction at clinical examination (2, 90). Careful pre-operative and/or arthroscopic examination often reveals evidence of subtle instability (i.e., labral tear, glenoid fracture, or Malgaigne (91) lesion) in majority of these patients (92). As subtle instability is only present in one direction and there is no associated hyperlaxity, the unstable painful shoulder should not be labeled as MDI or its variants.
Hyperlaxity
Hyperlaxity is constitutional, multidirectional, bilateral, and asymptomatic. It can result from systemic conditions or connective tissue disorders such as Marfan syndrome and Ehlers–Danlos syndrome (5). When generalized, hyperlaxity results in an increased range of motion of joints and distractibility (84) and is defined clinically with a Beighton score ≥4 (93). However, while the Beighton score can be easily performed, there is some concern that an elevated Beighton score does not translate to shoulder hyperlaxity, with published data showing poor correlation between the Beighton score and validated measures of shoulder laxity (5, 94). As such, with regard to the shoulder, hyperlaxity should be defined as increased mobility of the shoulder that is with an external rotation ≥85° with the elbow at the side (7, 95) (Fig. 3). Asymptomatic patients should again not be labeled as pathological laxity, regardless of the presence of generalized laxity or systemic collagen abnormalities. This non-pathological finding is a risk factor for instability but does not by itself demand treatment unless there is clear pathological laxity.
(A) Clinical photograph of a patient in supine position demonstrating external rotation of the left shoulder of 90º. (B) Lateral view of the same patient clearly demonstrates left shoulder external rotation of 90º.
Citation: EFORT Open Reviews 9, 4; 10.1530/EOR-23-0029
Pathological laxity, MDIs, and hypermobile painful shoulders
Pathological laxity of the inferior glenohumeral ligament is observed when passive abduction in neutral rotation in the glenohumeral joint is above 105°, if there is apprehension above 90° of abduction, or if a difference of more than 20° between the two shoulders is noted (96, 97).
MDIs represent a symptomatic instability of the glenohumeral joint as clearly shown by the present study. This was the most striking commonality among all the studies reviewed, with 67/68 (98.5%) in agreement. Another point of contention is the number of directions of instability (two vs three), and whether inferior instability is required to make a diagnosis of MDI. Neer and Foster’s original description stated that diagnosis of MDI requires instability in two or more planes of motion (1). In this review, 28/68 (41.2%) of the studies required two or more directions of instability, of which one had to be inferior, 16/68 (23.5%) of the studies followed the original description, simply requiring instability in two or more planes of motion, even in the absence of inferior instability, and 15/68 (22.1%) of the studies necessitate a global instability involving anterior, posterior, and inferior directions. As it stands, if the definition of MDI is made to mandatorily include inferior instability, almost one-quarter of the studies reviewed would be void. Certainly, while inferior instability is a sign of inferior capsular pathological laxity, the authors advocate that combined anterior and posterior instability should also be included within the MDI definition.
In addition, there appears to be no consensus in the articles within this systematic review regarding etiology. This may be heavily influenced by Matsen’s classic description of the AMBRI shoulder – that an atraumatic etiology is often the case in multidirectional instability. In addition, it is thought that the predominant pathophysiology of MDI is a redundant and capacious capsule (31, 76, 98). With such capsules, there is a large patulous inferior capsule and enlarged rotator interval. These abnormalities can result in an overall increased joint laxity due to the increase in the capsular volume. It is controversial whether or not overuse, repetitive microtrauma or overt major trauma significantly worsens the capsular integrity. Perhaps this thought process resulted in 36/68 (52.9%) of the studies excluding trauma as an etiology in the definition of MDI. While the authors agree that capsular hyperlaxity is likely pathophysiology for MDI, it is also important to consider traumatic MDI as a variant, as patients can often present in a similar fashion. This is the reason why any new classification should acknowledge the effect that trauma and its associated traumatic lesions can have on the definition and treatment of MDIs. The effect of a traumatic etiology can also differ between the hyperlax and normolax shoulder. Conceptually, the hyperlax shoulder may suffer less damage than a normolax shoulder for the same trauma, due to a lower inherent stability. Even though 25/68 (36.8%) of the reviewed studies excluded labral and bony injuries, the authors believe that the presence of such injuries should be accounted for within the classification as it can have a significant effect on treatment options and outcomes.
It thus appears that two multidirectional pathological hyperlaxity coexist: first, the classical MDI is a true subluxation or dislocation of the shoulder associated with structural lesions. It mostly occurs after trauma on young patients with hyperlaxity. Clinically, patients present an apprehension in more than one direction. Imaging reveals labral lesions and treatment is based on surgery associating repair of lesions and concomitant capsular shift. Secondly, the painful hypermobile shoulder occurs involuntarily in young hyperlax patients, often without any history of trauma. The complaint is mostly pain during mobilization, with or without subluxation, misdiagnosed as dislocation, and the treatment is conservative.
Voluntary dislocators
Voluntary dislocators can voluntarily reproduce subluxation or dislocation without distress. If these individuals were to be included within the definition of MDI, it would introduce significant heterogeneity as it is well accepted that these individuals do not require surgical treatment. A common demographic of these voluntary dislocators are children and pre-adolescents. The treatment of these patients would be for them to simply cease the habit (99). In the present review, 24/68 (35.3%) of the studies explicitly excluded voluntary dislocators. However, we included within the definition reproducible dislocators (that could have been previously voluntary dislocators); these individuals are able to reproduce a dislocation, even if this induces pain.
AB symptomatic multidirectional pathological laxity classification
Given the aforementioned controversies, it is timely for a new classification system to be established. Our proposed classification utilizes history taking and physical examination, which are both fundamental aspects of diagnosing MDI (Table 1). We excluded advanced imaging findings intentionally in an attempt to simplify the classification and improve its utility. In addition, this classification can also serve to differentiate pathological patients from physiological laxity who may not need advanced imaging in the first place.
Proposed classification of symptomatic multidirectional pathological laxity (AB symptomatic multidirectional pathological laxity classification).
| Normolax | Hyperlax | |
|---|---|---|
| Atraumatic (A) | A1 Atraumatic MDI | A2 Hypermobile painful shoulder |
| Traumatic (B) | B1 Traumatic MDI | B2 Hyperlax MDI |
The authors classify symptomatic multidirectional pathological laxity primarily as traumatic or atraumatic. The implications on treatment are that patients with a traumatic etiology may have concurrent labral or bony lesions in addition to a capacious capsule, which can be further refined through subsequent imaging workup. This can increase the technical difficulties in dealing with this subset of symptomatic multidirectional pathological laxity and requires more elements of surgical intervention. In addition, these ‘combination’ injuries cannot be compared to a pure MDI without bony lesions.
This classification divides patients with dynamic instability in two or more planes into two distinct groups, A and B, based on the presence of a traumatic etiology. This makes differentiating patients simple, as it can be performed based on clinical history alone. Within the groups, they are further differentiated based on the presence of hyperlaxity. This can be achieved by physical examination of the patients. As such, the AB classification can be easily utilized in the outpatient setting.
A1: Atraumatic MDI
Clinical presentation: Patients in this group present with symptomatic multidirectional instability without a traumatic etiology. It is important to differentiate this group from voluntary dislocators, who are asymptomatic.
Axial T2-weighted MRI scan of the right shoulder revealing a capacious joint capsule with no associated labral or bony lesions.
Citation: EFORT Open Reviews 9, 4; 10.1530/EOR-23-0029
Physical examination: There will be pathological instability in two or more directions of the shoulder joint. Patients are normolax and should not demonstrate ≥85° of external rotation of the shoulder joint.
Imaging: Standard radiographs of the shoulder joint may not demonstrate any abnormality, but MRI will reveal a capacious joint capsule and an absence of associated labral or bony lesions (Fig. 4).
Treatment: These patients will benefit from an initial course of physiotherapy. In the event of failure of non-surgical treatment, pancapsular plication (open or arthroscopic) can be considered. Surgical outcomes of group A patients are often less effective compared to group B patients due to the lack of discrete labral or osseous deficiencies (36, 100).
A2: Hypermobile painful shoulder
Clinical presentation: The hypermobile painful shoulder occurs in young patients without any history of trauma. The complaint is mostly pain during mobilization, with or without subluxation, and can be misdiagnosed as dislocation. These patients might have been previously voluntary dislocators that became reproducible ones.
Physical examination: There will be pathological instability in two or more directions of the shoulder joint. However, pain and/or subluxation is often the predominant sign, rather than overt dislocation. Patients will demonstrate hyperlaxity, as determined by ≥85° of external rotation of the shoulder joint.
Imaging: Standard radiographs of the shoulder joint may not demonstrate any abnormality but MRI will reveal a capacious joint capsule and an absence of associated labral or bony lesions.
Treatment: Non-surgical treatment is recommended in this subset of patients (101, 102).
Analgesics and physiotherapy with an emphasis on strengthening of the rotator cuff, deltoid, and peri-scapular stabilizers have yielded positive results (47).
B1: Traumatic MDI
Clinical presentation: Patients in this group present with symptomatic multidirectional instability after a traumatic etiology. Repetitive microtrauma is not deemed as a traumatic etiology.
(A) Anteroposterior plain radiograph showing Hill–Sachs and reverse Hill–Sachs lesions. (B) Axial CT arthrogram of the right shoulder showing the presence of a Hill–Sachs and reverse Hill–Sachs lesion.
Citation: EFORT Open Reviews 9, 4; 10.1530/EOR-23-0029
Physical examination: There will be pathological instability in two or more directions of the shoulder joint. Patients are normolax and should not demonstrate ≥85° of external rotation of the shoulder joint.
Imaging: Standard radiographs of the shoulder joint should be carefully assessed for bony lesions of the glenoid and humeral head. Advanced imaging such as MRI is recommended to identify the presence of associated isolated or circumferential labral lesions, as well as bony lesions of the glenoid and humeral head (Fig. 5). There are often combination injuries resulting in the multidirectional nature of instability.
Treatment: The ideal treatment is dependent on the symptomology, patient characteristics, and the extent of associated labral/osseous injuries. There should be a low threshold for surgical intervention in the event of persistent symptoms. Treatment consists of repair of the labral/osseous lesions and a concomitant capsular shift.
B2: Hyperlax MDI
Clinical presentation: Patients in this group present with symptomatic multidirectional instability after a traumatic etiology.
Axial T2-weighted MRI scan of the right shoulder revealing a Hill–Sachs lesion (star), posterior labral lesion (arrow) with a capacious joint capsule.
Citation: EFORT Open Reviews 9, 4; 10.1530/EOR-23-0029
Physical examination: There will be pathological instability in two or more directions of the shoulder joint. Examination may reveal multidirectional subluxation and/or dislocation. Patients will demonstrate hyperlaxity, as determined by ≥85° of external rotation of the shoulder joint.
Imaging: Standard radiographs of the shoulder joint should be carefully assessed for bony lesions of the glenoid and humeral head. MRI will reveal a capacious joint capsule in addition to associated isolated or circumferential labral lesions, as well as bony lesions of the glenoid and humeral head (Fig. 6).
Treatment: The ideal treatment is dependent on the symptomology, patient characteristics and the extent of associated labral/osseous injuries. There should be a low threshold for surgical intervention in the event of persistent symptoms.
It is the authors’ intention that, with this new classification system, the various subtypes of symptomatic multidirectional pathological laxity can be more accurately defined and compared. The strengths of this classification system are that it is easy to use and takes into consideration the classical controversies of symptomatic multidirectional pathological laxity, mainly: trauma as an etiology and the presence of pathological laxity. Doing so will allow for a more precise scientific analysis of symptomatic multidirectional pathological laxity and its treatment outcomes. This classification will also allow the inclusion of heterogenous studies that have previously been performed.
Conclusion
Multidirectional instability 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 concomitant pathological laxity can provide a more precise assessment of the various existing subtypes of multidirectional instability.
Supplementary materials
This is linked to the online version of the paper at https://doi.org/10.1530/EOR-23-0029.
ICMJE Conflict of Interest Statement
Alexandre Lädermann is a paid consultant for Stryker, Arthrex, and Medacta. He is the founder of FORE, BeeMed, and Med4Cast. He owns stock options of Medacta and Follow Health. The other authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the study reported.
Funding Statement
The study was funded by FORE (Foundation for Research and Teaching in Orthopedics, Sports Medicine, Trauma and Imaging in the Musculoskeletal System) (grant no. FORE 2022-38).
Patient consent
Written informed consent for publication of clinical details and/or clinical images was obtained from the patient/parent/guardian/relative of the patient.
References
- 1↑
Neer CS, & Foster CR. Inferior capsular shift for involuntary inferior and multidirectional instability of the shoulder: a preliminary report. Journal of Bone and Joint Surgery 1980 62 897–908. (https://doi.org/10.2106/00004623-198062060-00004)
- 2↑
Patte D, Bernageau J, Rodineau J, & Gardes JC. Unstable painful shoulders (author's transl). Revue de Chirurgie Orthopedique et Reparatrice de l'Appareil Moteur 1980 66 157–165.
- 3↑
Navlet MG, & Asenjo-Gismero CV. Multidirectional instability: natural history and evaluation. Open Orthopaedics Journal 2017 11 861–874. (https://doi.org/10.2174/1874325001711010861)
- 4↑
Saccomanno MF, Fodale M, Capasso L, Cazzato G, & Milano G. Generalized joint laxity and multidirectional instability of the shoulder. Joints 2013 1 171–179. (https://doi.org/10.11138/jts/2013.1.4.171)
- 5↑
Nourissat G, Vigan M, Hamonet C, Doursounian L, & Deranlot J. Diagn osis of Ehlers-Danlos syndrome after a first shoulder dislocation. Journal of Shoulder and Elbow Surgery 2018 27 65–69. (https://doi.org/10.1016/j.jse.2017.05.028)
- 6↑
Smits-Engelsman B, Klerks M, & Kirby A. Beighton score: a valid measure for generalized hypermobility in children. Journal of Pediatrics 2011 158 119–123 .e4. (https://doi.org/10.1016/j.jpeds.2010.07.021)
- 7↑
Chahal J, Leiter J, McKee MD, & Whelan DB. Generalized ligamentous laxity as a predisposing factor for primary traumatic anterior shoulder dislocation. Journal of Shoulder and Elbow Surgery 2010 19 1238–1242. (https://doi.org/10.1016/j.jse.2010.02.005)
- 8↑
Rockwood C. Subl uxation of the shoulder-classification, diagnosis and treatment. Journal of Bone and Joint Surgery-British Volume 1980 62 268.
- 9↑
Thomas SC, & Matsen FA 3rd. An approach to the repair of avulsion of the glenohumeral ligaments in the management of traumatic anterior glenohumeral instability. Journal of Bone and Joint Surgery 1989 71 506–513. (https://doi.org/10.2106/00004623-198971040-00005)
- 10↑
Gerber C, & Nyffeler RW. Classification of glenohumeral joint instability. Clinical Orthopaedics and Related Research® 2002 400 65–76. (https://doi.org/10.1097/00003086-200207000-00009)
- 11↑
Kuhn JE. A new classification system for shoulder instability. British Journal of Sports Medicine 2010 44 341–346. (https://doi.org/10.1136/bjsm.2009.071183)
- 12↑
McFarland EG, Kim TK, Park HB, Neira CA, & Gutierrez MI. The effect of variation in definition on the diagnosis of multidirectional instability of the shoulder. Journal of Bone and Joint Surgery 2003 85 2138–2144. (https://doi.org/10.2106/00004623-200311000-00011)
- 13↑
Warby SA, Pizzari T, Ford JJ, Hahne AJ, & Watson L. Exercise-based management versus surgery for multidirectional instability of the glenohumeral joint: a systematic review. British Journal of Sports Medicine 2016 50 1115–1123. (https://doi.org/10.1136/bjsports-2015-094970)
- 14↑
Higgins JP & & Green S Cochrane Handbook for Systematic Reviews of Interventions. London, UK: The Cochrane Collaboration 2011.
- 15↑
Lebar RD, & Alexander AH. Multidirectional shoulder instability: clinical results of inferior capsular shift in an active-duty population. American Journal of Sports Medicine 1992 20 193–198. (https://doi.org/10.1177/036354659202000217)
- 16↑
Alpert JM, Verma N, Wysocki R, Yanke AB, & Romeo AA. Arthroscopic treatment of multidirectional shoulder instability with minimum 270 labral repair: minimum 2-year follow-up. Arthroscopy: the Journal of Arthroscopic and Related Surgery 2008 24 704–711. (https://doi.org/10.1016/j.arthro.2008.01.008)
- 17↑
Bak K, Spring BJ, & Henderson JP. Inferior capsular shift procedure in athletes with multidirectional instability based on isolated capsular and ligamentous redundancy. American Journal of Sports Medicine 2000 28 466–471. (https://doi.org/10.1177/03635465000280040501)
- 18↑
Caplan J, Julien TP, Michelson J, & Neviaser RJ. Multidirectional instability of the shoulder in elite female gymnasts. American Journal of Orthopedics 2007 36 660–665.
- 19↑
Castagna A, Cesari E, Gigante A, Di Matteo B, Garofalo R, & Porcellini G. Age-related changes of elastic fibers in shoulder capsule of patients with glenohumeral instability: a pilot study. BioMed Research International 2018 2018 8961805. (https://doi.org/10.1155/2018/8961805)
- 20↑
Choi CH, & Ogilvie-Harris DJ. Inferior capsular shift operation for multidirectional instability of the shoulder in players of contact sports. British Journal of Sports Medicine 2002 36 290–294. (https://doi.org/10.1136/bjsm.36.4.290)
- 21↑
Duncan R, & Savoie FH III. Arthroscopic inferior capsular shift for multidirectional instability of the shoulder: a preliminary report. Arthroscopy 1993 9 24–27. (https://doi.org/10.1016/s0749-8063(0580340-8)
- 22↑
Engelsma Y, & Willems WJ. Arthroscopic stabilization of posterior shoulder instability. Knee Surgery, Sports Traumatology, Arthroscopy 2010 18 1762–1766. (https://doi.org/10.1007/s00167-010-1110-8)
- 23↑
Fitzgerald BT, Watson BT, & Lapoint JM. The use of thermal capsulorrhaphy in the treatment of multidirectional instability. Journal of Shoulder and Elbow Surgery 2002 11 108–113. (https://doi.org/10.1067/mse.2002.121476)
- 24↑
Frostick SP, Sinopidis C, Al Maskari S, Gibson J, Kemp GJ, & Richmond JC. Arthroscopic capsular shrinkage of the shoulder for the treatment of patients with multidirectional instability: minimum 2-year follow-up. Arthroscopy 2003 19 227–233. (https://doi.org/10.1053/jars.2003.50034)
- 25↑
Gartsman GM, Roddey TS, & Hammerman SM. Arthroscopic treatment of multidirectional glenohumeral instability: 2-to 5-year follow-up. Arthroscopy 2001 17 236–243. (https://doi.org/10.1053/jars.2001.21529)
- 26↑
Joseph TA, Williams JS Jr, & Brems JJ. Laser capsulorrhaphy for multidirectional instability of the shoulder: an outcomes study and proposed classification system. American Journal of Sports Medicine 2003 31 26–35. (https://doi.org/10.1177/03635465030310011601)
- 27↑
Kim SH, Kim HK, Sun JI, Park JS, & Oh I. Arthroscopic capsulolabroplasty for posteroinferior multidirectional instability of the shoulder. American Journal of Sports Medicine 2004 32 594–607. (https://doi.org/10.1177/0363546503262170)
- 28↑
Kiss J, Damrel D, Mackie A, Neumann L, & Wallace WA. Non-operative treatment of multidirectional shoulder instability. International Orthopaedics 2001 24 354–357. (https://doi.org/10.1007/s002640000202)
- 29↑
Kjær BH, De Wandele I, Spanhove V, Juul-Kristensen B, & Cools AM. Subacromial space outlet in female patients with multidirectional instability based on hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder measured by ultrasound. Journal of Shoulder and Elbow Surgery 2020 29 600–608. (https://doi.org/10.1016/j.jse.2019.08.003)
- 30↑
Krishnan SG, Hawkins RJ, Horan MP, Dean M, & Kim YK. A soft tissue attempt to stabilize the multiply operated glenohumeral joint with multidirectional instability. Clinical Orthopaedics and Related Research 2004 429 256–261. (https://doi.org/10.1097/01.blo.0000146468.08655.ab)
- 31↑
Lee HJ, Kim NR, Moon SG, Ko SM, & Park JY. Multidirectional instability of the shoulder: rotator interval dimension and capsular laxity evaluation using MR arthrography. Skeletal Radiology 2013 42 231–238. (https://doi.org/10.1007/s00256-012-1441-2)
- 32↑
Levy O, Wilson M, Williams H, Bruguera J, Dodenhoff R, & Sforza Ga CS. Thermal capsular shrinkage for shoulder instability: mid-term longitudinal outcome study. Journal of Bone and Joint Surgery 2001 83 640–645. (https://doi.org/10.1302/0301-620x.83b5.11374)
- 33↑
Lim CO, Park KJ, Cho BK, Kim YM, & Chun KA. A new screening method for multidirectional shoulder instability on magnetic resonance arthrography: labro-capsular distance. Skeletal Radiology 2016 45 921–927. (https://doi.org/10.1007/s00256-016-2364-0)
- 34↑
Lo IK, Nonweiler B, Woolfrey M, Litchfield R, & Kirkley A. An evaluation of the apprehension, relocation, and surprise tests for anterior shoulder instability. American Journal of Sports Medicine 2004 32 301–307. (https://doi.org/10.1177/0095399703258690)
- 35↑
Lyons TR, Griffith PL, Savoie FH III, & Field LD. Laser-assisted capsulorrhaphy for multidirectional instability of the shoulder. Arthroscopy 2001 17 25–30. (https://doi.org/10.1053/jars.2001.20663)
- 36↑
Ma HL, Huang HK, Chiang ER, Wang ST, Hung SC, & Liu CL. Arthroscopic pancapsular plication for multidirectional shoulder instability in overhead athletes. Orthopedics 2012 35 e497–e502. (https://doi.org/10.3928/01477447-20120327-15)
- 37↑
Misamore GW, Sallay PI, & Didelot W. A longitudinal study of patients with multidirectional instability of the shoulder with seven-to ten-year follow-up. Journal of Shoulder and Elbow Surgery 2005 14 466–470. (https://doi.org/10.1016/j.jse.2004.11.006)
- 38↑
Mitchell BC, Siow MY, Carroll AN, Pennock AT, & Edmonds EW. Clinical outcomes, survivorship, and return to sport after arthroscopic capsular repair with suture anchors for adolescent multidirectional shoulder instability: results at 6-year follow-up. Orthopaedic Journal of Sports Medicine 2021 9 2325967121993879. (https://doi.org/10.1177/2325967121993879)
- 39↑
Mohtadi NG, Hollinshead RM, Ceponis PJ, Chan DS, & Fick GH. A multi-centre randomized controlled trial comparing electrothermal arthroscopic capsulorrhaphy versus open inferior capsular shift for patients with shoulder instability: protocol implementation and interim performance: lessons learned from conducting a multi-centre RCT [ISRCTN68224911; NCT00251160]. Trials 2006 7 4. (https://doi.org/10.1186/1745-6215-7-4)
- 40↑
Mohtadi NG, Kirkley A, Hollinshead RM, McCormack R, MacDonald PB, Chan DS, Sasyniuk TM, Fick GH, Paolucci EO & Joint Orthopaedic Initiative for National Trials of the Shoulder-Canada. Electrothermal arthroscopic capsulorrhaphy: old technology, new evidence: a multicenter randomized clinical trial. Journal of Shoulder and Elbow Surgery 2014 23 1171–1180. (https://doi.org/10.1016/j.jse.2014.02.022)
- 41↑
Morris AD, Kemp GJ, & Frostick SP. Shoulder electromyography in multidirectional instability. Journal of Shoulder and Elbow Surgery 2004 13 24–29. (https://doi.org/10.1016/j.jse.2003.09.005)
- 42↑
Ogston JB, & Ludewig PM. Differences in 3-dimensional shoulder kinematics between persons with multidirectional instability and asymptomatic controls. American Journal of Sports Medicine 2007 35 1361–1370. (https://doi.org/10.1177/0363546507300820)
- 43↑
Pollock RG, Owens JM, Flatow EL, & Bigliani LU. Operative results of the inferior capsular shift procedure for multidirectional instability of the shoulder. Bone and Joint Surgery 2000 82 919–928. (https://doi.org/10.2106/00004623-200007000-00003)
- 44↑
Raynor MB, Horan MP, Greenspoon JA, Katthagen JC, & Millett PJ. Outcomes after arthroscopic pancapsular capsulorrhaphy with suture anchors for the treatment of multidirectional glenohumeral instability in athletes. American Journal of Sports Medicine 2016 44 3188–3197. (https://doi.org/10.1177/0363546516659644)
- 45↑
Schaeffeler C, Waldt S, Bauer JS, Kirchhoff C, Haller B, Schröder M, Rummeny EJ, Imhoff AB, & Woertler K. MR arthrography including abduction and external rotation images in the assessment of atraumatic multidirectional instability of the shoulder. European Radiology 2014 24 1376–1385. (https://doi.org/10.1007/s00330-014-3133-x)
- 46↑
Sciascia A, Kuschinsky N, Nitz AJ, Mair SD, & Uhl TL. Electromyographical comparison of four common shoulder exercises in unstable and stable shoulders. Rehabilitation Research and Practice 2012 2012 783824. (https://doi.org/10.1155/2012/783824)
- 47↑
Spanhove V, De Wandele I, Kjær BH, Malfait F, Vanderstukken F, & Cools A. The effect of five isometric exercises on glenohumeral translations in healthy subjects and patients with the hypermobility type of the Ehlers-Danlos syndrome (HEDS) or hypermobility spectrum disorder (HSD) with multidirectional shoulder instability: an observational study. Physiotherapy 2020 107 11–18. (https://doi.org/10.1016/j.physio.2019.06.010)
- 48↑
Spanhove V, Calders P, Berckmans K, Palmans T, Malfait F, Cools A, & De Wandele I. Electromyographic muscle activity and three-dimensional scapular kinematics in patients with multidirectional shoulder instability: a study in the hypermobile type of the Ehlers-Danlos syndrome and the hypermobility spectrum disorders. Arthritis Care and Research 2022 74 833–840. (https://doi.org/10.1002/acr.24525)
- 49↑
Toth AP, Warren RF, Petrigliano FA, Doward DA, Cordasco FA, Altchek DW, & O’Brien SJ. Thermal shrinkage for shoulder instability. HSS Journal 2011 7 108–114. (https://doi.org/10.1007/s11420-010-9187-7)
- 50↑
Treacy SH, Savoie FH III, & Field LD. Arthroscopic treatment of multidirectional instability. Journal of Shoulder and Elbow Surgery 1999 8 345–350. (https://doi.org/10.1016/s1058-2746(9990158-1)
- 51↑
Vavken P, Tepolt FA, & Kocher MS. Open inferior capsular shift for multidirectional shoulder instability in adolescents with generalized ligamentous hyperlaxity or Ehlers-Danlos syndrome. Journal of Shoulder and Elbow Surgery 2016 25 907–912. (https://doi.org/10.1016/j.jse.2015.10.010)
- 52↑
Voigt C, Schulz AP, & Lill H. Arthroscopic treatment of multidirectional glenohumeral instability in young overhead athletes. Open Orthopaedics Journal 2009 3 107–114. (https://doi.org/10.2174/1874325000903010107)
- 53↑
Warby SA, Pizzari T, Ford JJ, Hahne AJ, & Watson L. The effect of exercise-based management for multidirectional instability of the glenohumeral joint: a systematic review. Journal of Shoulder and Elbow Surgery 2014 23 128–142. (https://doi.org/10.1016/j.jse.2013.08.006)
- 54↑
Warby SA, Ford JJ, Hahne AJ, Watson L, Balster S, Lenssen R, & Pizzari T. Comparison of 2 exercise rehabilitation programs for multidirectional instability of the glenohumeral joint: a randomized controlled trial. American Journal of Sports Medicine 2018 46 87–97. (https://doi.org/10.1177/0363546517734508)
- 55↑
Watson L, Balster S, Lenssen R, Hoy G, & Pizzari T. The effects of a conservative rehabilitation program for multidirectional instability of the shoulder. Journal of Shoulder and Elbow Surgery 2018 27 104–111. (https://doi.org/10.1016/j.jse.2017.07.002)
- 56↑
Yeargan SA III, Briggs KK, Horan MP, Black AK, & Hawkins RJ. Determinants of patient satisfaction following surgery for multidirectional instability. Orthopedics 2008 31 647. (https://doi.org/10.3928/01477447-20110505-20)
- 57↑
Zabinski SJ, Callaway GH, Cohen S, & Warren RF. Revision shoulder stabilization: 2-to 10-year results. Journal of Shoulder and Elbow Surgery 1999 8 58–65. (https://doi.org/10.1016/s1058-2746(9990057-5)
- 58↑
D'Alessandro DF, Bradley JP, Fleischli JE, & Connor PM. Prospective evaluation of thermal capsulorrhaphy for shoulder instability: indications and results, two-to five-year follow-up. American Journal of Sports Medicine 2004 32 21–33. (https://doi.org/10.1177/0095399703258735)
- 59↑
Perkins SA, & Massie JE. Patient satisfaction after thermal shrinkage of the glenohumeral-joint capsule. Journal of Sport Rehabilitation 2001 10 157–163. (https://doi.org/10.1123/jsr.10.3.157)
- 60↑
Staker JL, Braman JP, & Ludewig PM. Kinematics and biomechanical validity of shoulder joint laxity tests as diagnostic criteria in multidirectional instability. Brazilian Journal of Physical Therapy 2021 25 883–890. (https://doi.org/10.1016/j.bjpt.2021.10.001)
- 61↑
Illyés A, & Kiss RM. Kinematic and muscle activity characteristics of multidirectional shoulder joint instability during elevation. Knee Surgery, Sports Traumatology, Arthroscopy 2006 14 673–685. (https://doi.org/10.1007/s00167-005-0012-7)
- 62↑
Jalovaara P, Myllylä V, & Päivänsalo M. Autotraction stress roentgenography for demonstration anterior and inferior instability of the shoulder joint. Clinical Orthopaedics and Related Research 1992 284 136–143. (https://doi.org/10.1097/00003086-199211000-00017)
- 63↑
Kiss RM, Illyés A, & Kiss J. Physiotherapy vs. capsular shift and physiotherapy in multidirectional shoulder joint instability. Journal of Electromyography and Kinesiology 2010 20 489–501. (https://doi.org/10.1016/j.jelekin.2009.09.001)
- 64↑
Lippitt SB, Harris SL, Harryman DT, Sidles J, & Matsen FA. In vivo quantification of the laxity of normal and unstable glenohumeral joints. Journal of Shoulder and Elbow Surgery 1994 3 215–223. (https://doi.org/10.1016/S1058-2746(0980038-4)
- 65↑
Nyiri P, Illyés A, Kiss R, & Kiss J. Intermediate biomechanical analysis of the effect of physiotherapy only compared with capsular shift and physiotherapy in multidirectional shoulder instability. Journal of Shoulder and Elbow Surgery 2010 19 802–813. (https://doi.org/10.1016/j.jse.2010.05.008)
- 66↑
Park KJ, Jeong HS, Park JK, Cha JK, & Kang SW. Evaluation of inferior capsular laxity in patients with atraumatic multidirectional shoulder instability with magnetic resonance arthrography. Korean Journal of Radiology 2019 20 931–938. (https://doi.org/10.3348/kjr.2018.0541)
- 67↑
Witney-Lagen C, Hassan A, Doodson A, & Venkateswaran B. Arthroscopic plication for multidirectional instability: 50 patients with a minimum of 2 years of follow-up. Journal of Shoulder and Elbow Surgery 2017 26 e29–e36. (https://doi.org/10.1016/j.jse.2016.07.015)
- 68↑
Yoldas EA, Faber KJ, & Hawkins RJ. Translation of the glenohumeral joint in patients with multidirectional and posterior instability: awake examination versus examination under anesthesia. Journal of Shoulder and Elbow Surgery 2001 10 416–420. (https://doi.org/10.1067/mse.2001.116650)
- 69↑
Wichman MT, & Snyder SJ. Arthroscopic capsular plication formultidirectional instability of the shoulder. Operative Techniques in Sports Medicine 1997 5 238–243. (https://doi.org/10.1016/S1060-1872(9780007-X)
- 70↑
Baker CL, Mascarenhas R, Kline AJ, Chhabra A, Pombo MW, & Bradley JP. Arthroscopic treatment of multidirectional shoulder instability in athletes: a retrospective analysis of 2-to 5-year clinical outcomes. American Journal of Sports Medicine 2009 37 1712–1720. (https://doi.org/10.1177/0363546509335464)
- 71↑
Barden JM, Balyk R, Raso VJ, Moreau M, & Bagnall K. Dynamic upper limb proprioception in multidirectional shoulder instability. Clinical Orthopaedics and Related Research 2004 420 181–189. (https://doi.org/10.1097/00003086-200403000-00025)
- 72↑
Barden JM, Balyk R, Raso VJ, Moreau M, & Bagnall K. Atypical shoulder muscle activation in multidirectional instability. Clinical Neurophysiology 2005 116 1846–1857. (https://doi.org/10.1016/j.clinph.2005.04.019)
- 73↑
Chen D, Goldberg J, Herald J, Critchley I, & Barmare A. Effects of surgical management on multidirectional instability of the shoulder: a meta-analysis. Knee Surgery, Sports Traumatology, Arthroscopy 2016 24 630–639. (https://doi.org/10.1007/s00167-015-3901-4)
- 74↑
Dewing CB, McCormick F, Bell SJ, Solomon DJ, Stanley M, Rooney TB, & Provencher MT. An analysis of capsular area in patients with anterior, posterior, and multidirectional shoulder instability. American Journal of Sports Medicine 2008 36 515–522. (https://doi.org/10.1177/0363546507311603)
- 75↑
Emery RJ, & Mullaji AB. Glenohumeral joint instability in normal adolescents. Incidence and significance. Journal of Bone and Joint Surgery 1991 73 406–408. (https://doi.org/10.1302/0301-620X.73B3.1670438)
- 76↑
Hsu YC, Pan RY, Shih YY, Lee MS, & Huang GS. Superior-capsular elongation and its significance in atraumatic posteroinferior multidirectional shoulder instability in magnetic resonance arthrography. Acta Radiologica 2010 51 302–308. (https://doi.org/10.3109/02841850903524421)
- 77↑
Jacobson ME, Riggenbach M, Wooldridge AN, & Bishop JY. Open capsular shift and arthroscopic capsular plication for treatment of multidirectional instability. Arthroscopy 2012 28 1010–1017. (https://doi.org/10.1016/j.arthro.2011.12.006)
- 78↑
Longo UG, Rizzello G, Loppini M, Locher J, Buchmann S, Maffulli N, & Denaro V. Multidirectional instability of the shoulder: a systematic review. Arthroscopy 2015 31 2431–2443. (https://doi.org/10.1016/j.arthro.2015.06.006)
- 79↑
Lubiatowski P, Ogrodowicz P, Wojtaszek M, Breborowicz M, Długosz J, & Romanowski L. Arthroscopic capsular shift technique and volume reduction. European Journal of Orthopaedic Surgery and Traumatology 2012 22 437–441. (https://doi.org/10.1007/s00590-011-0865-z)
- 80↑
Moon YL, Singh H, Yang H, & Chul LK. Arthroscopic rotator interval closure by purse string suture for symptomatic inferior shoulder instability. Orthopedics 2011 34. (https://doi.org/10.3928/01477447-20110228-02)
- 81↑
Jobe FW, Kvitne RS, & Giangarra CE. Shoulder pain in the overhand or throwing athlete. The relationship of anterior instability and rotator cuff impingement. Orthopaedic Review 1989 18 963–975.
- 82↑
Rowe CR, & Zarins B. Recurrent transient subluxation of the shoulder. Journal of Bone and Joint Surgery 1981 63 863–872. (https://doi.org/10.2106/00004623-198163060-00001)
- 83↑
Beasley L, Faryniarz DA, & Hannafin JA. Multidirectional instability of the shoulder in the female athlete. Clinics in Sports Medicine 2000 19 331–349. (https://doi.org/10.1016/s0278-5919(0570207-6)
- 84↑
Guerrero P, Busconi B, Deangelis N, & Powers G. Congenital instability of the shoulder joint: assessment and treatment options. Journal of Orthopaedic and Sports Physical Therapy 2009 39 124–134. (https://doi.org/10.2519/jospt.2009.2860)
- 85↑
Lädermann A, Denard PJ, Tirefort J, Kolo FC, Chagué S, Cunningham G, & Charbonnier C. Does surgery for instability of the shoulder truly stabilize the glenohumeral joint? A prospective comparative cohort study. Medicine 2016 95 e4369. (https://doi.org/10.1097/MD.0000000000004369)
- 86↑
Blasier RB, Soslowsky LJ, Malicky DM, & Palmer ML. Posterior glenohumeral subluxation: active and passive stabilization in a biomechanical model. Journal of Bone and Joint Surgery. American Volume 1997 79 433–440. (https://doi.org/10.2106/00004623-199703000-00018)
- 87↑
Gerber C, & Ganz R. Clinical assessment of instability of the shoulder. With special reference to anterior and posterior drawer tests. Journal of Bone and Joint Surgery. British Volume 1984 66 551–556. (https://doi.org/10.1302/0301-620X.66B4.6746691)
- 88↑
Tzannes A, & Murrell GA. Clinical examination of the unstable shoulder. Sports Medicine 2002 32 447–457. (https://doi.org/10.2165/00007256-200232070-00004)
- 89↑
Gerber C, Terrier F, & Ganz R. The Trillat procedure for recurrent anterior instability of the shoulder. Journal of Bone and Joint Surgery 1988 70 130–134. (https://doi.org/10.1302/0301-620X.70B1.3339045)
- 90↑
Boileau P, Zumstein M, Balg F, Penington S, & Bicknell RT. The unstable painful shoulder (UPS) as a cause of pain from unrecognized anteroinferior instability in the young athlete. Journal of Shoulder and Elbow Surgery 2011 20 98–106. (https://doi.org/10.1016/j.jse.2010.05.020)
- 92↑
Malgaigne JF, & Baillière J. Traité des fractures et des luxations. Paris: Chez J. B Baillière 1855.
- 93↑
Grahame R, Bird HA, & Child A. The revised (Brighton 1998) criteria for the diagnosis of benign joint hypermobility syndrome (BJHS). Journal of Rheumatology 2000 27 1777–1779.
- 94↑
Whitehead NA, Mohammed KD, & Fulcher ML. Does the Beighton score correlate with specific measures of shoulder joint laxity? Orthopaedic Journal of Sports Medicine 2018 6 2325967118770633. (https://doi.org/10.1177/2325967118770633)
- 95↑
Walch G, Agostini JY, Levigne C, & Nové-Josserand L. Recurrent anterior and multidirectional instability of the shoulder. Revue de Chirurgie Orthopedique et Reparatrice de l'Appareil Moteur 1995 81 682–690.
- 96↑
Gagey O. The hyperabduction test: an assessment of the laxity of the inferior glenohumeral ligament. Journal of Bone and Joint Surgery 2001 83 69–74.
- 97↑
Hovelius L, & Rahme H. Primary anterior dislocation of the shoulder: long-term prognosis at the age of 40 years or younger. Knee Surgery, Sports Traumatology, Arthroscopy 2016 24 330–342. (https://doi.org/10.1007/s00167-015-3980-2)
- 98↑
Provencher MT, Dewing CB, Bell SJ, McCormick F, Solomon DJ, Rooney TB, & Stanley M. An analysis of the rotator interval in patients with anterior, posterior, and multidirectional shoulder instability. Arthroscopy 2008 24 921–929. (https://doi.org/10.1016/j.arthro.2008.03.005)
- 99↑
Lewis A, Kitamura T, & Bayley JIL. (ii) The classification of shoulder instability: new light through old windows! Current Orthopaedics 2004 18 97–108. (https://doi.org/10.1016/j.cuor.2004.04.002)
- 100↑
Coudane H, & Walch G. L’instabilité antérieure chronique de l’épaule chez l’adulte. Revue de Chirurgie Orthopedique 1999 86(Supplement1) 91–150.
- 101↑
Johnson SM, & Robinson CM. Shoulder instability in patients with joint hyperlaxity. Journal of Bone and Joint Surgery 2010 92 1545–1557. (https://doi.org/10.2106/JBJS.H.00078)
- 102↑
Mallon WJ, & Speer KP. Multidirectional instability: current concepts. Journal of Shoulder and Elbow Surgery 1995 4 54–64. (https://doi.org/10.1016/s1058-2746(1080009-6)
