Updated: 1/2/2023

Multidirectional Shoulder Instability (MDI)

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  • summary
    • Multidirectional shoulder instability (MDI) is a condition characterized by generalized instability of the shoulder in at least 2 planes of motion (anterior, posterior, or inferior) due to capsular redundancy. 
    • Diagnosis is made clinically with presence of increased anterior and posterior humeral translation, a sulcus sign, and overall increased external rotation.
    • Treatment is a trial of prolonged physical therapy focusing on dynamic stabilization and periscapular muscle training. Arthroscopic stabilization with capsular shift is indicated for patients with persistent instability who fail an extensive course of physical therapy. 
  • Epidemiology
    • Incidence
      • peaks in second and third decades of life
  • Etiology
    • Pathophysiology
      • mechanisms
        • underlying mechanism includes
          • microtrauma from overuse
            • seen with overhead throwing, volleyball players, swimmers, gymnasts
          • generalized ligamentous laxity
            • associated with connective tissue disorders: Ehlers-Danlos and Marfan's
      • pathoanatomy
        • hallmark findings of MDI
          • Imaging findings: patulous inferior capsule on MRI (IGHL anterior and posterior bands)
          • rotator interval deficiency
        • labral lesions or glenoid erosion can still occur from traumatic events
          • Bankart lesion is anteroinferior labral tear
          • Kim lesion is posteroinferior labral avulsion
      • MDI is also referred to as AMBRI
        • Atraumatic
        • Multidirectional
        • Bilateral (frequently)
        • Rehabilitation (often responds to)
        • Inferior capsular shift (best alternative to nonop)
  • Anatomy
    • Glenohumeral stability
      • static restraints
        • glenohumeral ligaments (below)
        • glenoid labrum (below)
        • articular congruity and version
        • negative intraarticular pressure
          • if release head will sublux inferiorly
      • dynamic restraints
        • rotator cuff muscles
          • the primary biomechanical role of the rotator cuff is stabilizing the glenohumeral joint by compressing the humeral head against the glenoid
        • biceps
        • periscapular muscles
    • Complete Glenohumeral anatomy
  • Presentation
    • Symptoms
      • pain
      • instability
      • weakness
      • paresthesias
      • crepitus
      • shoulder instability during sleep
    • Physical exam
      • Tests - must have instability in 2 or more planes (anterior, posterior, or inferior) to be defined as MDI
        • sulcus sign (2+ or more)
          • assesses rotator interval
          • laxity of rotator interval presents as increased external rotation with the arm fully adducted and at 90 degrees abduction
        • apprehension/relocation test
        • anterior and posterior load and shift test (2+ or more)
        • Neer and Hawkins test
          • impingement or rotator cuff tendonitis in <20 year old signals possible MDI
      • signs of generalized hypermobility - generalized ligamentous laxity = Beighton's criteria >4/9
        • able to touch palms to floor while bending at waist (1 point)
        • genu recurvatum (2 points)
        • elbow hyperextension (2 points)
        • MCP hyperextension (2 points)
        • thumb abduction to the ipsilateral forearm (2 points)
  • Imaging
    • Radiographs
      • recommended views
        • a complete trauma series needed for evaluation (AP-IR, AP-ER, AP-True, Axillary, Scapular Y)
      • findings
        • may be normal in multidirectional instability
    • MRI
      • indications
        • to fully evaluate shoulder anatomy
        • arthrogram needed to assess volume of capsule
      • findings
        • patulous inferior capsule (IGHL anterior and posterior bands)
        • Bankart lesion - may occur in conjunction with traumatic anterior instability
        • Kim lesion - may occur in conjunction with traumatic posterior instability
        • bony erosion of glenoid - following chronic anterior instability
    • Arthroscopy
      • drive-through sign may be present
        • a positive drive-through sign is considered the ability to pass an arthroscope easily between the humeral head and the glenoid at the level of the anterior band of the IGHL
        • also associated with shoulder laxity
  • Differential Diagnosis
    • Anterior shoulder instability
    • Posterior shoulder instability
    • Cervical spine disease
    • Brachial plexitis
    • Thoracic outlet syndrome
  • Treatment
    • Nonoperative
      • dynamic stabilization physical therapy
        • indications
          • first line of treatment
          • vast majority of patients
        • technique
          • 3-6 month regimen needed
          • strengthening of dynamic stabilizers (rotator cuff and periscapular musculature)
          • closed kinetic chain exercises are used early in the rehabilitation process to safely stimulate co-contraction of the scapular and rotator cuff muscles
    • Operative
      • capsular shift / stabilization procedure (open or arthroscopic)
        • indications
          • failure of extensive nonoperative management
          • pain and instability that interferes with ADLs of sports activities
        • contraindications
          • voluntary dislocators
      • capsular reconstruction (allograft)
        • rare, described in refractory cases and patients with collagen disorders
  • Techniques
    • Capsular shift / stabilization procedure (open or arthroscopic)
      • approach
        • arthroscopic approach to shoulder
        • deltopectoral approach for open
          • subscapularis tenotomy versus subscapularis split
      • stabilization
        • must address capsule +/- rotator interval
        • inferior capsular shift (capsule shifted superiorly)
        • plication of redundant capsule in a balanced fashion
        • rotator interval closure (open or arthroscopic)
          • produces the most significant decrease in range of motion in external rotation with the arm at the side
        • address any anterior or posterior labral pathology if present
        • thermal capsulorrhaphy (historical)
          • is contraindicated because of complications including capsular thinning/insufficiency and attenuation, and chondrolysis
      • post-operative rehabilitation
        • 4-6 weeks: shoulder immobilizer or sling
        • 6-10 weeks: ADL's with 45 degree limit on abduction and external rotation
        • 10-16 weeks: gradual range of motion
        • >16 weeks: strengthening
        • >10 months: contact sports
        • patient should resume sports activities only after normal strength and motion have returned
  • Complications
    • Subscapularis deficiency
      • more common after open anterior-inferior capsular shift
      • may be caused by injury or failed repair
      • postop physical exam will show a positive lift-off test and excessive external rotation
      • late finding - humeral head anterior sublaxation on axillary radiograph
    • Loss of motion
      • may be due to asymmetric tightening or overtightening of capsule
      • leads to loss of ER
      • treat with Z-lengthening of subscapularis
      • rare
    • Axillary nerve injury
      • iatrogenic injury with surgery (abduction and ER moves axillary nerve away from glenoid)
      • usually a neuropraxia that can be observed postoperatively
      • can occur with anterior dislocation of shoulder
    • Late arthritis (capsulorraphy induced arthritis)
      • usually wear of posterior glenoid with posterior humeral head subluxation and significant retroversion of the glenoid
      • may have internal rotation contracture (severe lack of external rotation on exam)
      • historically seen with Putti-Platt and Magnuson-Stack (non-anatomic, historical) procedures
    • Recurrence
      • most common complication following arthroscopic or open capsulorraphy
      • high rate following thermal capsulorrhaphy (historical) due to capsular insufficiency
        • open revision indicated (not arthroscopic)
Flashcards (2)
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Questions (17)

(OBQ18.164) A 13-year-old baseball pitcher presents with persistent pain of the right shoulder over the last 2 years. He denies any antecedent trauma or dislocations. They report sensations of instability when performing activities with external rotation and abduction. Physical examination reveals an internal rotation deficit of 10 degrees on the right shoulder. The patient is able to hyperextend the elbows and knees to 12 degrees, can place both palms on the floor with knees fully extended, and hyperextend the small finger MCP joint past 90 degrees. There is a positive anterior and posterior load and shift test with a positive sulcus sign. What is the likely diagnosis and next best step in management?

QID: 213060

Labral tear; MRI of the shoulder



Glenohumeral internal rotation deficit; sleeper stretches



Multidirectional instability; periscapular muscle training



SLAP tear; MRI arthrogram of the shoulder



Little leaguer's shoulder; refrain from pitching for 3 months



L 2 A

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(OBQ18.105) A 17-year-old gymnast comes to your clinic reporting multiple atraumatic shoulder dislocation events. She has been able to reduce her shoulder on her own without a single trip to the emergency department. Radiographs are normal and an MRI arthrogram is seen in Figure A. Which of the following physical exam findings is most likely to be present?

QID: 213001

Cross-body adduction test



O'Brien's Test



Axillary Webbing



Jobe’s Test



Increased external rotation in adduction



L 2 A

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(OBQ12.10) A 19-year-old female presents with bilateral shoulder pain and instability during volleyball practice. She denies any injuries. Physical exam elicits pain when her arm is internally rotated with her shoulder forward flexed to 90 degrees. In the seated position there is a 2cm sulcus present with inferior traction on each arm. Radiographs are unremarkable. Her representative MRI images from her right shoulder are seen in figures A and B, which are identical to her other side. What is the most appropriate initial treatment?

QID: 4370

Physical therapy



Bilateral glenohumeral corticosteriod injections and physical therapy



Bilateral subacromial corticosteriod injections and physical therapy



Bilateral staged arthroscopic labral repair and capsulorrhaphies



Bilateral staged open capsular shifts



L 2 B

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(OBQ10.137) Which of the following is true regarding closure of the rotator interval in patients undergoing arthroscopic shoulder stabilization?

QID: 3188

It can lead to recurrent instability



It restricts external rotation predominately in the "arm cocking" phase of throwing



It restricts combined flexion and cross-body adduction



It restricts external rotation predominately with the arm at 0 degrees of shoulder abduction



It restricts internal rotation predominately with the arm at 90 degrees of shoulder abduction



L 1 C

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(OBQ09.150) A 16-year-old swimmer has pain and weakness in her dominant shoulder with overhead use. Her physical examination demonstrates a +2 anterior and posterior load and shift test. There is 1.5cm of sulcus sign evident with the arm at adduction and 30 degrees of external rotation. Her radiographs are normal. What is the most appropriate next step in management?

QID: 2963

Arthroscopic anterior and posterior labral repair



Arthroscopic anterior and posterior labral repair with rotator interval closure



Home stretching program with emphasis on posterior capsular stretching



Dynamic stabilization therapy



Sport specific bracing



L 1 B

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(SAE07SM.97) What procedure can eliminate a sulcus sign?

QID: 8759

Rotator interval closure



SLAP repair



Bankart repair



Supraspinatus repair



Subacromial decompression



L 4 E

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(OBQ06.69) A freshman collegiate swimmer complains of right shoulder pain after increasing his workout duration and intensity. He denies trauma and admits to popping his shoulders in and out voluntarily since the age of 8. Exam reveals bilateral anterior shoulder apprehension and relocation, positive jerk test, and a 2cm sulcus bilaterally. O’Brien active compression tests are negative bilaterally. Radiographs are normal and MR arthrogram of his right shoulder is shown in Figures A and B. What is the best initial treatment?

QID: 180

Shoulder range of motion program with emphasis on posterior capsular stretching



Shoulder arthroscopy with anterior and posterior capsulolabral plication with superior shift



Shoulder arthroscopy with thermal capsulorrhaphy and rotator interval closure



Shoulder arthroscopy with repair of humeral avulsion of the glenohumeral ligament (HAGL) lesion



Rotator cuff and peri-scapular muscular strengthening program



L 2 B

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(OBQ05.51) A 20-year-old girl reports a shoulder dislocation while reaching for a high shelf. Her history reveals multiple past dislocations with spontaneous reduction and no obvious traumatic event at onset. A photograph of her hand is shown in figure A. What is the most likely etiology of her shoulder instability?

QID: 937

inverted pear glenoid with bone deficiency



long thoracic nerve palsy



Bankart lesion



capsular redundancy



Buford complex



L 1 D

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(OBQ04.51) An 18-year-old high school volleyball player is being treated for multidirectional instability of the right shoulder with a physical therapy program. She has intermittent pain and instability and episodic numbness and weakness in the ipsilateral hand. All of the following are characteristic features of a generalized connective tissue disorder EXCEPT:

QID: 1381

Elbow hyperextension of the left arm



Left 5th finger passive extension beyond 90°



Genu recurvatum of the bilateral knees



Excessive supination of the left forearm



Abducted thumb to reach the ipsilateral forearm (thumb-to-forearm test) of the right hand



L 2 D

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Evidence (36)
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