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Shoulder Motion Overestimated by Mallet Scores
Madison Lovette1, Ross S Chafetz2, Stephanie A Russo3
1Department of Biomedical Engineering, Cleveland State University, Cleveland, OH.
Insights
Clinical Mallet scores for brachial plexus birth injuries (BPBI) show significant inaccuracies, especially for external rotation and hand-to-mouth movements. Motion capture analysis revealed discrepancies, highlighting the need for improved assessment methods in pediatric care.
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.
Background:
Brachial plexus birth injuries (BPBI) occur in up 0.4 to 4.6 per 1000 live births. Weakness about the shoulder and development of glenohumeral joint contractures are common sequalae of BPBI. Shoulder function in children with BPBI is frequently assessed using the modified Mallet classification to evaluate upper extremity motion deficits. The purpose of this study was to assess the accuracy of the abduction, external rotation, and hand-to-mouth Mallet classification scores in children with BPBI using motion capture.
Methods:
A retrospective study of 107 children with BPBI who underwent motion capture assessment and Mallet scores on the same date were reviewed. Motion capture measurements were used to calculate humerothoracic elevation and external rotation joint angles in the abduction/hand-to-mouth and external rotation positions, respectively. The humerothoracic joint angles were converted to the corresponding Mallet scores. Discrepancies between the Mallet scores determined by clinicians and those determined by motion capture were assessed.
Results:
For abduction, 24.3% of Mallet scores were misclassified during clinical examination. Of the misclassified scores, 22 were overestimated by 1 point and 4 were underestimated by 1 point compared with motion capture. For external rotation, 72.9% of Mallet scores were misclassified during clinical examination. Only 5 patients had an HT elevation that was less than 40 degrees, with 4 of them (80%) having a Mallet hand-to-mouth score of 4. There were no differences in proportion of patients with HT elevation less than 40 degrees who had a Mallet score of 4 or a Mallet score less than 4.
Conclusions:
There was better agreement in global abduction Mallet scores compared with external rotation and hand-to-mouth Mallet scores. This difference was likely due to the complex compensatory strategies that patients employ while performing external rotation and hand-to-mouth positions. The inaccuracy of the clinically determined Mallet scores is alarming given that they are frequently utilized to assist with surgical indications and are commonly used as outcome measures.
Level Of Evidence:
Level IV Case series.
