Static and dynamic internal ulnar rotational stability in collegiate baseball pitchers

Area of Science:

• Orthopedic surgery
• Sports medicine
• Biomechanics

Background:

• The posterior oblique ligament (POL) stabilizes the elbow against internal rotational stress.
• Morphological changes in the POL may contribute to elbow instability, particularly in throwing athletes.
• Understanding the role of elbow flexors in stabilizing the POL is crucial for injury prevention and management.

Purpose of the Study:

• To determine if POL morphological changes impact ulnar internal rotational laxity in collegiate baseball pitchers.
• To investigate the potential role of elbow flexor muscles in restraining this laxity.

Main Methods:

• A cross-sectional study involving 53 collegiate pitchers.
• Ultrasound assessment of POL morphology and measurement of posteromedial ulnohumeral joint distance.
• Evaluation under valgus stress with and without brachial flexor muscle contraction.

Main Results:

• 34% of pitchers exhibited POL morphological changes.
• Pitchers with abnormal POL showed significantly greater joint gapping under valgus stress compared to those with normal POL.
• This difference in joint gapping was not significant when elbow flexors were activated.

Conclusions:

• Morphological abnormalities of the POL are associated with increased ulnar internal rotational laxity in asymptomatic collegiate baseball pitchers.
• Elbow flexor muscle activation can reduce joint gapping under valgus loading, indicating a compensatory stabilization role.
• These findings highlight the importance of dynamic muscular stabilization in managing POL-related rotatory instability.