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Shoulder Instability

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Other Names

  • Glenohumeral Instability
  • Anterior Shoulder Instability
  • Multidirectional Instability
  • MDI
  • Unidirectional Shoulder Instability
  • Traumatic Shoulder Instability
  • Atraumatic Shoulder Instability

Background

  • This page refers to multidirectional instability (MDI), chronic subluxation and recurrent dislocations of the Glenohumeral Joint
  • There is no clear definition of MDI, glenohumeral instability and shoulder instability is variable in the literature
    • For MDI, sometimes the sensation of instability occuring in more than one direction is sufficient
    • This is not commonly agreed upon by experts

History

  • MDI first described by Neer and Foster in 1980[1]

Epidemiology

  • General
    • Prevalence of non-pathologic hyperlaxity in the general population is estimated to be between 5 and 15%[2]
  • MDI
    • Incidence, prevalence largely unknown
    • 2008: 7% of shoulder operations in Norway due to MDI[3]
    • Most commonly seen in patients in their 2nd and 3rd decade (need citation)
  • Traumatic instability
    • Traumatic anterior instability accounts for 80-90% of instability experienced by young athletes[4]
    • Incidence reported to be up to 1.7% of general population[5]

Pathophysiology

  • There is no clear definition of MDI, glenohumeral instability and shoulder instability in the literature
    • No pathognomonic finding or widely standardized diagnostic criteria
    • Some literature references the Del Mar and Beighton scoring systems (see below), but these are not universally adopted
    • For MDI, some cite instability in two directions
    • Subsequently diagnosis, research, practice guidelines are lacking
  • In general, shoulder instability is pathological condition characterized by increased length and elasticity of normal glenohumeral joint restraints
    • Indicates deficiency in static or dynamic stabilizers of the glenohumeral joint
    • Subsequently, there is increased translation of the articular surface
    • In MDI, this can be from repetative microtrauma or overall joint hyperlaxity
    • This can also occur due to primary trauma from shoulder dislocation
  • Hyperlaxity by itself is not pathologic
    • May be present in asymptomatic patients or asymptomatic translation of the glenohumeral joint
  • Patients with anterior traumatic shoulder instability without true hyperlaxity
    • Can experience recurrent dislocations and subluxations due to primary injury to the capsulolabral complex, glenoid or humeral head
  • Patients with shoulder instability and hyperlaxity are more likely to experience recurrent subluxations than frank dislocations[6]
    • Due to microtrauma from overuse

Etiology

  • Typical etiology includes repetitive microtrauma imposed on a congenitally lax joint[7]
  • Some degree of imbalance in muscle strength, neuromuscular control and dysfunction scapular biomechanics
  • Most common mechanism for initial anterior dislocation is fall onto outstretched arm with abducted, externally rotated arm

Pathoanatomy

Associated Injuries


Risk Factors

  • Prior Injury (greatest risk)[8]
  • Age of first dislocation
  • Congenital Hyperlaxity/ Ligamentous laxity including
    • Ehler's Danlos Syndrome
    • Marphan Syndrome
    • Osteogenesis Imperfecta
    • Benign Hypermobility Syndrome
  • Age
  • Labral hypoplasia[9]
  • Glenoid size
  • Modifiable
    • Rotator cuff strength
    • Muscular imbalance
    • Activity level
  • Acquired hyperlaxity from Sports
    • Volleyball
    • Swimming
    • Gymnastics

Differential Diagnosis


Clinical Features

  • History
    • Important to clarify history of dislocations, subluxations or sensation of laxity
    • Any history of developmental delay, seizure disorder, collagen disorder, congenital problems
    • Clarify if the patient can volitionally dislocate their shoulder
    • Symptoms may include vague shoulder pain with sports or demanding activities
    • May endorse recurrent dislocations and/or subluxations
    • In atraumatic cases, pain is usually insidious in onset
    • Patients may endorse declining athletic performance
    • Less commonly parasthesias, weakness
    • Symptoms may occur while sleeping
  • Physical Exam: Physical Exam Shoulder
    • Important to compare to contralateral arm
    • Examination is best performed through provocative testing
  • Special Tests
  • Anterior Instability/ Laxity
  • Posterior Instability/ Laxity
    • Kim Test: Arm abducted to 90°, apply axial load and elevate arm cranial and anterior
    • Jerk Test: Arm abducted to 90°, internally rotated with axial load and arm is abducted anteriorly in same plane
    • Posterior Apprehension Test: Apply a posterior force through flexed, adducted shoulder
    • Posterior Shoulder Drawer Test: with arm flexed and in partial traction, apply a posterior directed force
  • Inferior laxity Instability/ Laxity
    • Sulcus Sign: Place axial traction on affected limb with arm resting at side
    • Gagey Test: Hyperabduct arm to barrier or as patient tolerates

Evaluation

Radiographs

CT

  • Helpful to better evaluate bone abnormalities

MRI

  • Best imaging modality for soft tissue pathology
  • Can add arthrogram to better evaluate labrum and capsule
  • MDI: Hallmark finding is pathologic inferior capsule (IGHL, anterior and posterior bands)
  • May also show Bankart Lesion, Kim Lesion

Classification

Hospital Del Mar Score

  • Can be used to assess, quantify hyperlaxity[10]
    • Score ranges from 0-10
    • Score of 4/10 (men) or 5/10 (women) or higher suggests generalized joint laxity
  • Criteria
    • Passive hyperextension of the metacarpophalangeal joint of the little finger of 90° or more
    • Passive apposition of the thumb to the flexor aspect of the forearm at less than 21 mm
    • Passive elbow hyperextension of 10° or more
    • Passive shoulder external rotation of 85° or more
    • Passive hip abduction of 85° or more
    • Hyperextension of the first metatarsophalangeal joint beyond 90°
    • Patellar hypermobility, defined as excessive passive displacement medially and laterally as assessed by three or more quadrants of displacement
    • Excessive range of passive ankle dorsiflexion and eversion of the foot with the knee flexed to 90°
    • Passive knee hyperflexion, defined as ‘knee makes contact with the buttock’
    • Appearance of ecchymoses after hardly noticed, minimal trauma (historical datum)

Beighton Criteria

  • Scoring system for hyperlaxity and shoulder instability[11]
    • Score ranges from 0-9
    • Score of 2+ increases likelihood of future instability
    • Ranallette et al: Score of 6 or greater indicative of hyperlaxity[12]
  • Criteria
    • Passive dorsiflexion of the fifth finger beyond 90°
    • Passive thumb opposition to the forearm
    • Active elbow hyperextension beyond 10°
    • Active knee hyperextension beyond 10°
    • Forward flexion of the trunk with knees fully extended so that the palms of the hands rest flat on the floor.

Management

Prognosis

  • Age of first dislocation is important prognostic indicator[13]
    • Dislocation under 20 years of age, 90% recurrence rate
    • Dislocation over 40, 10% recurrence rate
  • MDI
    • Conservative management strategies have had inconsistent results, some positive and some negative.

Nonoperative

  • Indications:
    • First line therapy in most cases
  • Activity modification
  • Physical Therapy
    • Strengthening dynamic stabilizers compensates for lack of stability in passive stabilizers[14]
    • Emphasis on strengthening Rotator Cuff, functional reduction of instability
    • Scapulothoracic training, core stability, proprioceptice exercise programs
  • Equipment: Shoulder Harness

Operative

  • Indications
    • Failure of conservative therapy
    • Unidirectional instability
  • Technique
    • MDI: inferior capsular shift, arthroscopic plication, thermal capsulorrphaphy
    • Others: glenoid osteotomy, labral augmentation, capsuloligamentous reconstruction
  • Surgical management should be individualized to address underlying cause of instability
  • In 98% of MDI cases, there are no pathognomonic findings on arthroscopy[15]

Rehab and Return to Play

Rehabilitation

  • Strengthening dynamic stabilizers compensates for lack of stability in passive stabilizers[16]
  • Emphasis on strengthening Rotator Cuff, functional reduction of instability
  • Scapulothoracic training, core stability, proprioceptice exercise programs

Return to Play

  • Systematic review: 60% of athletes returned to sport at the same level, 34% to a lower level and 2% did not return to sport[17]

Complications

  • Athletes with pathologic hyperlaxity or hypermobility are at risk of injury to other joints[18]
    • Including knee, ankle injuries
  • Surgical

See Also


References


  1. Alpert, Joshua M., et al. "Arthroscopic treatment of multidirectional shoulder instability with minimum 270 labral repair: Minimum 2-year follow-up." Arthroscopy: The Journal of Arthroscopic & Related Surgery 24.6 (2008): 704-711.
  2. Remvig L, Jensen DV, Ward RC. Epidemiology of general joint hypermobility and basis for the proposed criteria for benign joint hypermobility syndrome: review of the literature. J Rheumatol. 2007;34:804–809.
  3. Blomquist, Jesper, et al. "Shoulder instability surgery in Norway: the first report from a multicenter register, with 1-year follow-up." Acta orthopaedica 83.2 (2012): 165-170.
  4. Owens, BD, Duffey, ML, Nelson, BJ, DeBerardino, TM, Taylor, DC, Mountcastle, SB. The incidence and characteristics of shoulder instability at the United States Military Academy. Am J Sports Med. 2007;35(7):1168-1173.
  5. Simonet WT, Melton LJ, Cofield RH, Ilstrup DM. Incidence of anterior shoulder dislocation in Olmsted County, Minnesota. Clin Orthop Relat Res. 1984;186:186–91.
  6. An YH, Friedman RJ. Multidirectional instability of the glenohumeral joint. Orthop Clin North Am. 2000;31:275–285.
  7. Warby, Sarah A., et al. "The effect of exercise-based management for multidirectional instability of the glenohumeral joint: a systematic review." Journal of shoulder and elbow surgery 23.1 (2014): 128-142.
  8. Cameron, KL, Mountcastle, SB, Nelson, BJ. History of shoulder instability and subsequent injury during four years of follow-up: a survival analysis. J Bone Joint Surg Am. 2013;95(5):439-445
  9. Doukas, William C., and Kevin P. Speer. "Anatomy, pathophysiology, and biomechanics of shoulder instability." Orthopedic Clinics 32.3 (2001): 381-391.
  10. Bulbena A, Duró JC, Porta M, et al. Clinical assessment of hypermobility of joints: assembling criteria. J Rheumatol. 1992;19:115–122
  11. Beighton P, Horan F. Orthopaedic aspects of the Ehlers-Danlos syndrome. J Bone Joint Surg Br. 1969;51:444–453.
  12. Ranalletta M, Bongiovanni S, Suarez F, et al. Do patients with traumatic recurrent anterior shoulder instability have generalized joint laxity? Clin Orthop Relat Res. 2012;470:957–960
  13. c LH, Cavallaro WU. Primary anterior dislocation of the shoulder. Am J Surg. 1950;80(6):615–21. passim.
  14. Beasley L, Faryniarz DA, Hannafin JA. Multidirectional instability of the shoulder in the female athlete. Clin Sports Med 2000;19:331–49
  15. Choi, C. H., and D. J. Ogilvie-Harris. "Inferior capsular shift operation for multidirectional instability of the shoulder in players of contact sports." British journal of Sports medicine 36.4 (2002): 290-294.
  16. Beasley L, Faryniarz DA, Hannafin JA. Multidirectional instability of the shoulder in the female athlete. Clin Sports Med 2000;19:331–49
  17. Longo, Umile Giuseppe, et al. "Multidirectional instability of the shoulder: a systematic review." Arthroscopy: The Journal of Arthroscopic & Related Surgery 31.12 (2015): 2431-2443.
  18. Decoster LC, Bernier JN, Lindsay RH, et al. Generalized joint hypermobility and its relationship to injury patterns among NCAA lacrosse players. J Athl Train. 1999;34:99–105
  19. Boileau P, Richou J, Lisai A, et al. The role of arthroscopy in revision of failed open anterior stabilization of the shoulder. Arthroscopy. 2009;25:1075–1084.
Created by:
John Kiel on 17 June 2019 19:16:59
Authors:
Last edited:
13 April 2022 10:50:43