Loss of Midline Function in Brachial Plexus Birth Palsy Patients
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Updated: Feb 5, 2026

Methods for In Vivo Biomechanical Testing on Brachial Plexus in Neonatal Piglets
Published on: December 19, 2019
Joshua M Abzug1, Theresa O Wyrick-Glover2, Alexandria L Case1
1Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD.
Insights
Loss of midline function in brachial plexus birth palsy (BPBP) patients can hinder daily activities. Derotational humeral osteotomy effectively restores this function after other surgeries cause loss of midline function.
Area of Science:
- Pediatric Orthopedics
- Reconstructive Surgery
- Pediatric Rehabilitation
Background:
- Loss of midline function significantly impacts daily living activities in children.
- Brachial plexus birth palsy (BPBP) can lead to impaired midline function.
- Assessing etiology and treatment for BPBP patients with loss of midline function is crucial.
Purpose of the Study:
- To evaluate brachial plexus birth palsy (BPBP) patients experiencing loss of midline function.
- To investigate the causes and treatment outcomes for this specific patient group.
- To analyze the effectiveness of surgical interventions on midline function.
Main Methods:
- Retrospective review of BPBP patients with loss of midline function.
- Utilized the modified Mallet scale to assess internal rotation (hand on spine, hand to belly).
- Collected data on demographics, BPBP extent, surgical history, and outcomes.
Main Results:
- Twenty patients with loss of midline function (inability to touch umbilicus) were identified.
- Tendon transfers for external rotation improved some Mallet scores but decreased midline function.
- Derotational humeral osteotomy restored midline function, improving internal rotation scores by an average of 47.8 degrees.
Conclusions:
- Surgical procedures for shoulder external rotation in BPBP patients can compromise midline function.
- Derotational humeral osteotomy is an effective treatment for restoring essential midline function.
- Future surgical approaches should prioritize preserving midline function in BPBP management.
Background:
Loss of midline function impairs the child's ability to perform certain activities of daily living such as dressing, buttoning, and perineal care. The purpose of this study was to assess brachial plexus birth palsy (BPBP) patients with loss of midline function with respect to etiology and treatment.
Methods:
A retrospective review of all BPBP patients with loss of midline function was performed. The modified Mallet scale was used with internal rotation assessed via hand on spine and hand to belly. Demographics, extent of BPBP, prior surgical intervention, procedure(s) performed to correct the loss of midline function, complications, and outcomes were assessed.
Results:
In total, 20 patients were identified with loss of midline function as defined by the inability to reach midline and touch their umbilicus. Nineteen patients had previously undergone tendon transfers about the shoulder with or without arthroscopic capsular release to improve external rotation. After the initial surgery, modified Mallet scores improved 1 grade for abduction, hand to mouth, hand to neck, and external rotation without altering the hand to spine category. However, the internal rotation category (hand to umbilicus) decreased from an average 2.71 preoperatively to an average 2.15 postoperatively. Nine patients underwent a derotational humeral osteotomy to improve midline function. The average correction of internal rotation was 47.8 degrees (range, 20 to 85 degrees). After this surgery, modified Mallet scores remained unchanged for hand to spine; however, the scores improved back to 2.7 for the internal rotation category. Two complications were noted including 1 plate fracture and 1 fracture through a screw hole.
Conclusions:
BPBP patients who undergo surgical procedures to improve shoulder external rotation and/or obtain joint reduction may inadvertently lose midline function. Derotational humeral osteotomy can effectively restore midline function, which is needed to perform activities of daily living. Surgical procedures to improve external rotation should be performed in a manner that minimizes limitation of midline functions.
Level Of Evidence:
Level III-therapeutic.
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