Multidirectional Shoulder Instability (MDI)

Authors

Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

To read

• Nonoperative and postoperative rehabilitation for glenohumeral instability¹

Multidirectional instability (MDI) of the shoulder has many definitions within medical literature. Originally, MDI was described by Neer and Foster as shoulder instability/dislocations in 2 or more directions with little to no trauma^2,3

Epidemiology

• Generally, MDI patients are young people who provoke a shoulder subluxation³
  • Most commonly seen in the 20s and 30s⁴
  • Less common past 40 years old due to age related physiologic changes causing stiffening of the shoulder joint⁴

Risk Factors

“Multidirectional instability can be influenced by a number of coexisting anatomical factors. Neer and Foster [1] believe that the main cause of instability in an excessively large, loose joint capsule, while other authors also draw attention to morphological changes in the glenoidal cavity and failure of the glenohumeral ligament [2–4]. Ligamentous laxity, upon which this disease develops, may be congenital. In such case, the symptoms usually appear on both sides or are acquired through repetitive microtrauma during sports activities.”³

Etiology

There are two primary causes of Multidirectional Instability of the shoulder (MDI):

1. Repetive Microtrauma^2,4
2. Generalized Connective Tissue Laxity^2,4

Repetitive Microtrauma

• Repetitive microtrauma can lead to long term increases in glenohumeral volume and lead to decreased stability²
• Repetitive Microtrauma is most commonly seen in overhead (OH) athletes⁴
  • Baseball Pitchers⁴
  • Volleyball⁴
  • Gymnasts⁴
  • Swimmers⁴

General CT Laxity

• General laxity can caused by a number of disorders:
  • Ehler-Danlos Syndrome⁴
  • Marfan Syndrome⁴
  • Osteogenesis Imperfecta⁴
  • Benign Joint Hypermobility Syndrome⁴
  • And more

Pathophysiology

• MDI can be described as an imbalance between the factors associated with shoulder mobility and shoulder stability resulting in an inability to maintain congruency of the glenohumeral joint⁴.
• Shoulder stabilizers:
  • Static Stabilizers Glenoid⁴
    • Glenoid labrum complex⁴
    • Glenohumeral ligaments⁴
    • Negative joint pressure⁴
  • Dynamic Stabilizers
    • Rotator Cuff⁴
    • Biceps Brachii Long Head⁴

Clinical Presentation

• The leading symptoms
  • Pain³
  • Upper limb instability and disability with an abnormal movement pattern³

Associated Injuries

• associated capsulolabral or bony lesions were reported in 16 studies²
• A bony lesion was found in 24 shoulders²

Examination

“Objective measures of glenohumeral laxity are not necessarily indicative of instability or the need for surgical management. Only when compensatory mechanisms fail may structural deficiencies become apparent, and patients may experience symptomatic instability. There is no pathognomonic finding for MDI, and no standardized criteria in the literature define MDI.”²

• Sulcus sign was used in 3 of the studies²

Joint Mobility

• GHJ Hyperlaxity
  • Present in 85% of patients with UPS⁵

Note

Shoulder joint laxity itself is not a sign of concern. The clinician should be looking for joint laxity in the presence of pain⁴.

Aggravating Tests

• Anterior Apprehension Test
• Posterior and Anterior Load & Shift Test⁴
  • Can be positive in these patients
• Sulcus Sign/Test
  • The most consistent finding in MDI⁴
  • Indicative of a loose rotator interval⁴
• Gagey Hyperabduction Test

Easing Tests

• Jobe Relocation Test⁵

Patient Reported Outcomes

• Rowe Score
• Single Assessment Numeric Evaluation (SANE) score

DDX

Other pathologies should be ruled out before diagnosing a patient with MDI:

• Unidirectional instability⁴
• Cervical spine disease⁴
• Os Acromiale⁴
• Thoracic Outlet Syndrome⁴

Prognosis

MDI is considered to have a good prognosis and that is why long periods of physical therapy (3-6 months) are generally recommended before invasive treatment⁴.

Management

Tests for goal setting

• ER/IR Ratio
• Modified ROWE Score

Surgical managements

• 372 (43%) shoulders MDI was managed arthroscopically²
• 226 (26%) shoulders,18,21,24-27,31,33 an open capsular shift procedure was used²
• Bankart repair in 5 (0.6%) shoulders²
• Anterior or posterior hamstring graft reconstruction in 3 (0.3%) shoulders⁶
• Posterior bone block and posterior shift in 2 (0.2%) shoulders²
• reported arthroscopic thermal capsular shrinkage for MDI²
• 55 (6%) shoulders, reported arthroscopic laser-assisted capsulorrhaphy²
• Arthroscopic plication was performed in the remaining 268 (31%) shoulders²
• Forty-seven shoulders15 also underwent thermal capsular shrinkage after arthroscopic plication because the capsule was considered insufficiently tightened²

Conservative Management

• 29% of the participants underwent conservative management in²

In physical therapy, the primary approach with treatment will be to correct the imbalance between shoulder stabilization and shoulder mobility by focusing on the dynamic stabilizers of the shoulder⁴.

• Training RTC
• Training Periscapular musculature
• CKC exercises should be implemented to improve neuromuscular co-contraction during coordinated movements⁴

Note

Conservative treatment is recommended for 3-6 months before more aggressive and invasive treatments should be considered⁴

“In all patients presenting with MDI, a first rehabilitative course is warranted. Neer stated that initial treatment of MDI should consider a change in lifestyle, use within pain limits, and exercises below the horizontal to strengthen the rotator and deltoid muscles”²

“The nonsurgical goal is to improve the efficiency of dynamic glenohumeral stabilizers. Strengthening of the rotator cuff may improve concavity compression with improved humeral head centering, leading to a functional reduction of instability.8 Proprioceptive exercise programs, scapulothoracic training, and core stability are the main columns of nonsurgical management. Motivated patients with appropriate protocols typically respond well and may not need further management.9 However, variable results have been reported.”²

³

References

1.

Wilk KE, Macrina LC. Nonoperative and postoperative rehabilitation for glenohumeral instability. Clinics in Sports Medicine. 2013;32(4):865-914. doi:10.1016/j.csm.2013.07.017

2.

Longo UG, Rizzello G, Loppini M, et al. Multidirectional Instability of the Shoulder: A Systematic Review. Arthroscopy: The Journal of Arthroscopic & Related Surgery: Official Publication of the Arthroscopy Association of North America and the International Arthroscopy Association. 2015;31(12):2431-2443. doi:10.1016/j.arthro.2015.06.006

3.

Kłaptocz P, Solecki W, Grzegorzewski A, Błasiak A, Brzóska R. Effectiveness of conservative treatment of multidirectional instability of the shoulder joint. Literature review and meta-analysis. Polski Przeglad Chirurgiczny. 2021;94(1):6-11. doi:10.5604/01.3001.0015.2415

4.

Johnson DJ, Tadi P. Multidirectional Shoulder Instability. In: StatPearls. StatPearls Publishing; 2024. Accessed April 21, 2024. http://www.ncbi.nlm.nih.gov/books/NBK557726/

5.

Ren H, Bicknell RT. From the unstable painful shoulder to multidirectional instability in the young athlete. Clinics in Sports Medicine. 2013;32(4):815-823. doi:10.1016/j.csm.2013.07.014

6.

Longbrake E. Myelin Oligodendrocyte Glycoprotein–Associated Disorders. CONTINUUM: Lifelong Learning in Neurology. 2022;28(4):1171-1193. doi:10.1212/CON.0000000000001127