THROWING PAIN IN YOUTH BASEBALL PLAYERS: EVIDENCE THAT MONITORING GROWTH,
PITCH SPEED AND LOSS OF INTERNAL ROTATION MAY HELP PREVENT INJURIES
Elliot M. Greenberg PT, DPT, PhD, OCS1,2 ; J. Todd Lawrence MD, PhD1 ; Alicia Fernandez-Fernandez PT, DPT, PhD3 ; Philip McClure, PT, PhD, FAPTA2
1- Children’s Hospital of Philadelphia, Sports Medicine and Performance Center, Philadelphia, PA 2-Arcadia University, Department of Physical Therapy, Glenside, PA; 3- Nova Southeastern University Department of Physical Therapy, Fort Lauderdale, FL
BACKGROUND
• 30-50% of youth baseball players suffer an upper extremity overuse injury within a
single season
• Identifying factors that contribute to these injuries is important for rehabilitation and
injury prevention
PURPOSE
To investigate differences in throwing specific anthropometric characteristics differed
between youth baseball players with and without a history of shoulder or elbow pain
RESULTS CONTINUED
Humeral Retrotorsion – Pain group had significantly less non-dominant
HRT resulting in greater asymmetry in HRT
Humeral Retrotorsion
Dominant HRT
80
(p=0.32)
Non-Dominant HRT
Asymmetry in HRT
(p=0.03)
¥ (p=0.03)
14
70
12
¥
60
10
Degrees
50
METHODS
• 84 baseball players aged 8-14 years-old (mean age: 11.5 years)
• Classified into two groups (pain / no pain) based upon self-reported history of shoulder
or elbow pain within the past 30 days
• Assessed for group differences in growth related, shoulder performance and baseball
specfic variables
VARIABLES OF INTEREST
Growth Related
• Age
• Height
• Weight
Baseball Exposure
• Months/year of baseball
• Pitching velocity
Shoulder Performance
Shoulder range of motion (ROM) - Side-to-side difference
(dominant – non-dominant):
• Glenohumeral Internal Rotation Difference (GIRD)
• Glenohumeral External Rotation Difference (GERD)
• Total Range of Motion difference (dTROM)
Humeral Retrotorsion (HRT)
• Dominant, non-dominant, side-to-side difference in HRT
(dHRT)
Shoulder Strength
• ratio of ER/IR force
MEASUREMENT PROCEDURES
Shoulder Range of Motion
Glenohumeral External
Rotation (ER)
Glenohumeral Internal
Rotation (IR)
8
¥
40
6
30
4
20
2
10
0
0
Pain
Bicipital groove identified with ultrasound and aligned with horizontal. Forearm
inclination gives relative torsional difference between proximal and distal humerus
RESULTS
Growth and Exposure - Pain group was taller, heavier and played more baseball
Variable
Height (cm)¥
Weight (kg) ¥
Months / Year of
Baseball¥
Pain (n=16)
No Pain (n=68)
Mean (median) ± Mean (median) ± SD P value
SD
148.2 (149.9) ± 11.4 0.001*
161.7 (160.2) ±
12.3
51.5 (51.8) ± 17.7
40.5 (39.4) ± 10.8
0.018*
10 (10) ± 1.9
8.9 (9) ± 1.9
0.040*
Shoulder Performance
Shoulder ROM - Pain group had significantly greater GIRD
dTROM (°)
Pain (n=16)
Mean (median) ±
SD
-0.5 (-1.0) ± 9.9
-0.6 (-0.3) ± 7.9
0.964
GIRD (°)
-9.1 (-8.7) ± 6.9
-5.2 (-4.7) ± 6.8
0.041*
GERD (°)
8.5 (7.3) ± 8.1
4.5 (3.6) ± 7.8
0.069
Variable
No Pain (n=68)
Mean (median) ± SD P Value
Pain Free
Pain
Pain Free
CONCLUSION
• Taller and heavier players with faster pitch velocities may be at an
inherently increased risk of injury.
• A 9.1° IR loss was associated with pain, indicating a lower tolerance for
IR loss may exist for youth baseball players compared to adults.
• Players with a history of pain had lower degrees of non-dominant HRT,
giving rise to a larger side-to-side asymmetry.
• HRT is a developmental characteristic. Players genetically predisposed
to having less HRT, may encounter more aggressive remodeling
stressors, resulting in an increased risk of injury.
CLINICAL RELEVANCE
• Body growth occurring during adolescence may increase a players risk
of injury.
• Careful monitoring of, and potentially addressing, IR ROM loss may
assist with injury prevention efforts.
• Assessment of HRT may provide clinicians with an additional measure
for individualized risk assessment, however further research is
necessary to firmly establish what the relationship of HRT to injury is.
ACKNOWLEDGEMENTS
Funding provided by the Legacy Fund, Sports Section of the APTA
Elliot Greenberg, PT, DPT, PhD, OCS [email protected]