Injuries in the Throwing Shoulder

David Conner MD

OrthoNortheast

4/25/15

Patient Population

• Throwers

• Volleyball

• Swimmers

• Tennis Player

The Thrower

• Concept of kinetic chain– Legs and trunk-> generate power– Shoulder->funnel and force regulator– Arm-> force delivery system

The Throwing Shoulder

• Perfect balance of mobility & stability

• “Thrower’s Paradox”– Lax enough to allow excessive

external rotation, but stable enough to prevent recurrent subluxation

The Set Point or Slot

• Excessive ER generates the velocity

• Throwers know ER “set point” to throw hard---known as “The Slot”

Phases of Throwing

• Late cocking- 165 degrees ER, 300 N anterior shear force

• Acceleration phase- 7,300 degrees/sec angular velocity• Deceleration- 1000 N distraction force

Potential for Disaster

• Significant motion

• Significant forces

Problem of the Throwing Shoulder

• “Dead Arm Syndrome”– Any pathologic shoulder condition where the

thrower is unable to throw with preinjury velocity and control because of combination of pain and subjective unease

• SLAP lesion• Internal Impingement• Cuff tear

SLAP Lesions ( Superior Labrum Anterior to Posterior)

• Snyder Classification

Internal Impingement

• Contact of Supraspinatus/infraspinatus & posterior- superior labrum in ABER (abduction/ external rotation)

• ? Physiologic or pathologicHumeral Retroversion

Crockett et al, AJSM, 2002• CT Scans bilateral shoulders• Humeral retroversion

– Dom = 40 deg– Non dom = 23 deg.

• Mean Diff between ER & IR Dom and Non dom, 7 & 9 deg

Dead Arm Syndrome: Theories

• Frank Jobe– Excessive ER causes micro stretch of anterior

capsule– Anterior instability causes internal/external

impingement– Internal Impingement causes SLAP lesion

• Burkhart & Morgan– Posterior capsule problem– SLAP lesion cause dead arm – No anterior instability present

Dead Arm Syndrome: Jobe Model

• Hyperangulation in ABER-Humerus left behind scapula

• Tensile overload of anterior capsule-subluxation

Dead Arm Syndrome: Jobe Model

• Muscles fatigue leading to pathologic internal impingement and subacromial impingement

• Secondary labral or cuff tears

Jobe Model

• Treatment-Eliminate anterior laxity– Surgical results

• Open capsular shift-> 50% return to play

• Halbrecht– Anterior instability DECREASES internal

impingement

Burkhart-Morgan Model

• Posterior capsular tightness

• Posterior-superior instability

• “Peel-back” mechanism-SLAP

• Anterior pseudoinstability

• Internal impingement

• Result: SLAP & cuff pathology

Throwers Develop Increased ER in Abduction

• Humeral retroversion

• Soft tissue adaptation

• Gain in ER should equal loss of IR

• Need 180 degree total arc

G.I.R.D

• Glenohumeral Internal Rotation Deficit

• Loss of ER compared to nonthrowing side

• Posteroinferior capsular contracture – THE ESSENTIAL LESION

GIRD

• Posteroinferior capsular tightness– Posterior band of inferoglenohumeral lig.– Traction phenomenon

GIRD-Tethered shoulder

• Ant IGHL & Post IGHL act as sling

GIRD-Tethered Shoulder

• Tight post IGHL tethers contact point – Moves pivot posterosuperiorly– Allows GT to clear glenoid-> increases ER

• Tight posteroinferior capsule– Hyper ER– Hyper horizontal ABD– Drop elbow– Premature trunk rotation

GIRD & Anterior Pseudolaxity

• Result: Able to increase ER by clearing GT and effective laxity of anterior capsule Get to “The Slot”

GIRD & The Slot

• With GIRD, increase in ER puts major stress on structures– Biceps anchor– Labrum – Cuff

“Peel-Back” Mechanism

• ABER-> biceps vector moves vertical and posterior– Torsion to posterior superior labrum– Posterior Type II SLAP

Peel-Back

SLAP Repair

• Simple suture at root better than tacks

• Repair SLAP, eliminates anterior pseudo laxity DO NOT NEED ANTERIOR STABILIZATION

SLAP Lesions

• Surgical debridement– Cordasco 1993

• 27 pts• 2 yr 63% G/E• 45% return to sport

– Altcheck 1992• 70% moderate pain @ 2 years

SLAP Lesion

• Repair with Suture Anchor– Burkhart 2000

• 124 pts• 2 yr• 90% excellent 10% good• 100% pitching @ 2 yrs

Dead Arm & the Rotator Cuff

• Tension• Compression—Internal Impingement

• Result: Partial Thickness Articular Sided RTC Tear

Dead Arm and RTC

• 31% of throwers with SLAP have RTC tear– 38% were complete RTC– 62% were PTRTC

The Problem

• Tight posterior capsule->posterosuperior shift-> Increased ER->Peel-back->Internal impingement/traction-> Cuff tear=Dead Arm

• Answer: Prevent Posterior capsular tightness

GIRD - Treatment

• Non-op

GIRD Non operative Treatment

• 90% throwers with symptomatic GIRD > 25 degrees respond to stretching in 2 weeks

• Best responders—young patients

GIRD - Treatment

• Operative

Glenoid

Capsule

Conclusion

• Dead arm- difficult clinical & radiographic diagnosis. Confirmed at arthroscopy

• Culprit- GIRD

• Best treatment- Prevention

• If symptomatic, SLAP usually present

• Look for cuff pathology

• Anterior laxity may exist, but don’t treat as initial problem

Young Throwing Shoulder

Pain – not normal

Common Problems

• Little League shoulder

• Mild instability

• Rotator cuff tendonitis

Little League Shoulder

• Adams, Calif Med 1966– “osteochondrosis of proximal humeral physis”

• Ages 11-14– Time of maximal prox humeral growth

• Rotational forces disrupt hypertrophic zone of physis– external rotation torque is estimated to be approximately 18 Nm

• 400% that physeal cartilage can take– distraction force estimated to be approximately 214.7 Nm

• 5% of what physis can tolerate– bone is much stronger in tension than with rotational stresses

X-rays

Widening of physis, metaphyseal demineralization and fragmentation, and periosteal reaction

Little League Shoulder• Physeal widening can persist after symptoms

resolve

MRI

wideningHigh intensity signal change adjacent to physis

Treatment• Relative rest (sling?)• No throwing 2-3 mos• Anti-inflammatory meds• Controlled return once

asymptomatic• Pitch Count• Rehab -Strengthen Trunk

Pitch Count Guidelines

• Rest requirements– >61 pitches 3 days– 41-60 2 days– 21-40 1 day– 0-20 0 days rest

• League Age – 17-18 105 pitches per

day– 13-16 95 pitches per

day– 11-12 85 pitches per

day– 9-10 75 pitches per

day– 7-8 50 pitches per

day

Carson & Gasser. Little leaguer’s shoulder. A report of 23 cases. Am J Sports Med 1998;

26:575–580.

• Excellent results protocol for return to play mentioned previous slide

• 21 of 23 patients (91%) were able to return to baseball at an average of 3 months (range: 1 month to 1 year) with asymptomatic shoulders

• Largest series to date

Prevention

• Information / education• Fitness exercises = general basis for all

sports participation• Avoid specialization• Begin training early (before season)• No more than 10% increase each week