Shoulder Motion Overestimated by Mallet Scores

Area of Science:

• Pediatric Orthopedics
• Biomedical Engineering
• Rehabilitation Medicine

Background:

• Brachial plexus birth injuries (BPBI) affect up to 4.6 per 1000 live births, commonly causing shoulder weakness and contractures.
• The modified Mallet classification is standard for assessing upper extremity motion deficits in children with BPBI.
• Accurate assessment is crucial for guiding surgical interventions and evaluating treatment outcomes.

Purpose of the Study:

• To evaluate the accuracy of Mallet classification scores for abduction, external rotation, and hand-to-mouth positions in children with BPBI.
• To compare clinical Mallet scores with objective measurements obtained via motion capture technology.

Main Methods:

• Retrospective review of 107 children with BPBI who had concurrent motion capture and Mallet scoring.
• Motion capture determined humerothoracic elevation and external rotation angles.
• Clinical Mallet scores were compared against motion capture-derived scores to identify discrepancies.

Main Results:

• Clinical abduction Mallet scores were misclassified in 24.3% of cases.
• External rotation Mallet scores showed higher inaccuracy, with 72.9% misclassified.
• Discrepancies were more pronounced in external rotation and hand-to-mouth assessments compared to abduction.

Conclusions:

• Significant inaccuracies exist in clinically applied Mallet scores for BPBI, particularly for external rotation and hand-to-mouth.
• Complex compensatory movements may contribute to the observed discrepancies.
• The unreliability of current clinical assessments is concerning for surgical decision-making and outcome tracking.