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Multidirectional Shoulder Instability (MDI)

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Topic updated on 05/29/16 5:36pm
Introduction
  • Also referred to as AMBRI
    • Atraumatic
    • Multidirectional
    • Bilateral (frequently)
    • Rehabilitation (often responds to)
    • Inferior capsular shift (best alternative to nonop)
  • Epidemiology
    • incidence
      • peaks in second and third decades of life
  • 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 
        • patulous inferior capsule (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
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
      • sulcus sign 
        • assesses rotator interval
      • apprehension/relocation test
      • load and shift test (posterior instability)
      • Neer and Hawkins test
        • impingement or rotator cuff tendonitis in <20 year old signals possible MDI
    • signs of generalized hypermobility
      • able to touch palms to floor while bending at waist
      • genu recurvatum
      • elbow hyperextension
      • MCP hyperextension
      • thumb abduction to the ipsilateral forearm
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
    • findings
      • patulous inferior capsule (IGHL anterior and posterior bands)
      • Bankart lesion
      • Kim lesion
      • bony erosion of glenoid
  • Arthroscopy
    • drive through sign may be present
Differential Diagnosis
  • Unidirectional 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 
    • 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
  • 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
    • usually wear of posterior glenoid
    • may have internal rotation contracture
    • historically seen with Putti-Platt and Magnuson-Stack (non-anatomic) procedures
  • Recurrence
    • high rate following thermal capsulorrhaphy
      • open revision indicated (not arthroscopic)

 

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Qbank (7 Questions)

TAG
(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? Topic Review Topic
FIGURES: A   B        

1. Physical therapy
2. Bilateral glenohumeral corticosteriod injections and physical therapy
3. Bilateral subacromial corticosteriod injections and physical therapy
4. Bilateral staged arthroscopic labral repair and capsulorrhaphies
5. Bilateral staged open capsular shifts

PREFERRED RESPONSE ▶
TAG
(OBQ10.137) Which of the following is true regarding closure of the rotator interval in patients undergoing arthroscopic shoulder stabilization? Topic Review Topic

1. It can lead to recurrent instability
2. It restricts external rotation predominately in the "arm cocking" phase of throwing
3. It restricts combined flexion and cross-body adduction
4. It restricts external rotation predominately with the arm at 0 degrees of shoulder abduction
5. It restricts internal rotation predominately with the arm at 90 degrees of shoulder abduction

PREFERRED RESPONSE ▶
TAG
(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? Topic Review Topic

1. Arthroscopic anterior and posterior labral repair
2. Arthroscopic anterior and posterior labral repair with rotator interval closure
3. Home stretching program with emphasis on posterior capsular stretching
4. Dynamic stabilization therapy
5. Sport specific bracing

PREFERRED RESPONSE ▶
TAG
(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? Topic Review Topic
FIGURES: A   B        

1. Shoulder range of motion program with emphasis on posterior capsular stretching
2. Shoulder arthroscopy with anterior and posterior capsulolabral plication with superior shift
3. Shoulder arthroscopy with thermal capsulorrhaphy and rotator interval closure
4. Shoulder arthroscopy with repair of humeral avulsion of the glenohumeral ligament (HAGL) lesion
5. Rotator cuff and peri-scapular muscular strengthening program

PREFERRED RESPONSE ▶
TAG
(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: Topic Review Topic

1. Elbow hyperextension of the left arm
2. Left 5th finger passive extension beyond 90°
3. Genu recurvatum of the bilateral knees
4. Excessive supination of the left forearm
5. Abducted thumb to reach the ipsilateral forearm (thumb-to-forearm test) of the right hand

PREFERRED RESPONSE ▶
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