Throwing
Wind-up
- cocking
- ER up to 180o in pitcher
Acceleration
- large scapular muscles
- acceleration - 7000o/sec
- rotatory acceleration similar to car tyre at 130 kph
Control and deceleration
- fragile cuff & glenohumeral ligament complex
Anatomy
Pitchers have increased ER range, but corresponding decreased IR range
- have increased humeral head retroversion
- probably from adaptations of growth plate whilst young
- "little leaguer's shoulder" may be part of this
They have a "normal" abnormality
Treatment of posterior capsular stretching in athletes is debatable
- limited IR is normal state
Problems / Spectrum
1. Subtle anterior instability / Posterior capsular contracture
- internal impingement
2. SLAP
3. Posterior instability
4. RC injuries
Internal Impingement Posterior / Superior Glenoid
Definition
Described by Davidson 1997
- throwing athletes
- impingement in ER and abduction
- classic 90 / 90 position
- posterior aspect of SS impinges on posterosuperior rim of glenoid
Pathology
Posterosuperior labrum is damaged
Cause
Argument whether posterior capsule tightness or anterior instability
- can be either
Symptoms
Usually posterior shoulder pain
Examination
Careful comparison of shoulders
- normal to have increased ER / decreased IR
EUA
- load and shift examination of instability very important
- need to examine shoulder in 90 / 90 position
- i.e. 90o ER and 90o abduction
- this is the throwing position
- look carefully for anterior instability
Diagnosis
Xray
Bennett's Lesion
MRI
- damaged posterosuperior labrum
- partial cuff tears
Arthroscopy
- place arthroscope anteriorly
- ER arm in 90o abducted position
- see posterior cuff impinge exactly on damaged area of labrum
Management
A. Posterior capsule tight and thickened
- feel / confirm thickening with probe
- careful release at edge of labrum
B. Shoulder unstable anteriorly in EUA
- may see anteroinferior labral injury
- may simple be redundant tissue
- anterior labral injury (careful repair with sutures)
- capsule stretched (advance part of capsule to glenoid rim to tighten)
NB Must be very careful
- cannot afford to lose ER in throwing athlete
Partial Thickness Tears Cuff
Pathology
Articular sided
- more posterior than in elderly
- at the SS / IS interval
- consistent with internal impingement
Associations
SLAP
Posterior capsular contracture
Aetiology
1. Repetitive trauma from massive eccentric forces in SS and IS during deceleration in throwing
2. Internal impingement from anterior subluxation / posterior tightness with posterior glenoid impingement and microtrauma
Non Operative
1. ROM / posterior capsular stretches
- decrease inflammation
- NSAIDS
2. Balanced RC exercises
Operative
Debridement is mainstay
- acromioplasty and repair rarely indicated
- some major league pitchers have full thickness tears
- repair initially may end career
Little Leaguer's Shoulder
Clinical
Present with painful shoulder
Xray
Physeal widening
Pathology
Chronic SH 1 growth plate
Management
Rest