What are Burkhart's and Richard Hawkins' theories on thrower's shoulder?

Burkhart's and Hawkins' Theories on Thrower's Shoulder

Burkhart's theory focuses on the "essential lesion" of posteroinferior capsular contracture leading to glenohumeral internal rotation deficit (GIRD), while Hawkins' theory emphasizes secondary impingement from rotator cuff dysfunction and atraumatic microinstability. 1

Burkhart's Theory: The Essential Lesion and GIRD

Burkhart's theory proposes a pathophysiological cascade that begins with:

1. The Essential Lesion: Thickening and contracture of the posteroinferior capsule resulting from repetitive tensile forces during the deceleration phase of throwing 1

2. Glenohumeral Internal Rotation Deficit (GIRD): The clinical manifestation of the essential lesion, characterized by decreased internal rotation of the throwing shoulder 2

3. Altered Biomechanics: The contracture shifts the glenohumeral contact point, leading to:

   • Increased external rotation
   • Posterosuperior migration of the humeral head during the late cocking phase
   • Development of a "peel-back" mechanism on the superior labrum 1

4. Consequences: This cascade ultimately results in:

   • SLAP lesions (superior labrum anterior-posterior tears)
   • Partial undersurface rotator cuff tears
   • Possible Bennett lesions (posterior glenoid osteophytes) 1

Hawkins' Theory: Secondary Impingement

Hawkins' theory focuses on:

1. Atraumatic Microinstability: Excessive laxity in the anterior capsule and ligaments of the glenohumeral joint 2

2. Rotator Cuff Dysfunction: Weakness of the rotator cuff muscles, particularly in youth throwers 3

3. Secondary Impingement: Difficulty maintaining the humeral head centered in the glenoid fossa during motion due to the combination of rotator cuff weakness and ligamentous laxity 2

4. Consequences: This leads to:

   • Undersurface rotator cuff tears from repetitive eccentric stress
   • Pain during the release and deceleration phases of throwing
   • Scapular dyskinesis as a compensatory mechanism 2

Key Differences Between the Theories

• Primary Pathology:

  • Burkhart: Begins with posterior capsular contracture (tightness)
  • Hawkins: Begins with anterior capsular laxity and rotator cuff weakness

• Mechanism of Injury:

  • Burkhart: Altered glenohumeral mechanics from posterior tightness
  • Hawkins: Secondary impingement from anterior instability

• Focus of Treatment:

  • Burkhart: Posterior capsular stretching and addressing the GIRD
  • Hawkins: Rotator cuff and scapular stabilizer strengthening

Clinical Implications

Both theories have influenced treatment approaches:

• For Burkhart's Theory: Treatment focuses on:

  • Posterior capsular stretching to address GIRD
  • Scapular stabilization
  • Core and lower body strengthening 1

• For Hawkins' Theory: Treatment emphasizes:

  • Strengthening rotator cuff muscles
  • Enhancing scapular stabilizers
  • Addressing the entire kinetic chain 2

Common Ground

Despite their differences, both theories recognize:

• The importance of the kinetic chain in throwing mechanics
• The role of scapular dyskinesis in shoulder pathology
• The need for comprehensive rehabilitation addressing multiple elements
• The interplay between mobility and stability (the "thrower's paradox") 2, 1

Both theories have contributed significantly to our understanding of the thrower's shoulder and continue to guide evaluation and treatment approaches for these complex injuries.