Upright MRI of glenohumeral dysplasia following obstetric brachial plexus injury

Subscapularis impairment on magnetic resonance imaging is correlated with functional limitations in neonatal brachial plexus palsy

PURPOSE

The relationship between functional shoulder deficits in children with neonatal brachial plexus palsy (NBPP) and magnetic resonance imaging (MRI) shoulder abnormalities was evaluated.

METHODS

Shoulder function was assessed in 16 children (mean age: 5.8 years; range: 3-12 years) with NBPP based on shoulder rotator muscle strength, as measured using an isokinetic dynamometer and the modified Mallet score. The thickness and fatty infiltration of the subscapularis and infraspinatus muscles, and the morphology of the glenoid on MRI, were also determined.

RESULTS

The highest subscapularis fatty infiltration subgroup of NBPP patients promoted the highest alteration muscle thickness and modified Mallet score.

CONCLUSIONS

In NBPP children, subscapularis impairments play a major role in the functional limitations. This study of pediatric NBPP patients highlighted the value of adding an examination of the muscles to routine MRI assessment of bone parameters in the shoulders of NBPP children.

TRIAL REGISTRATION

NCT03440658.

Risk factors at birth for permanent obstetric brachial plexus injury and associated osseous deformities

Purpose. To examine the most prevalent risk factors found in patients with permanent obstetric brachial plexus injury (OBPI) to identify better predictors of injury. Methods. A population-based study was performed on 241 OBPI patients who underwent surgical treatment at the Texas Nerve and Paralysis Institute. Results. Shoulder dystocia (97%) was the most prevalent risk factor. We found that 80% of the patients in this study were not macrosomic, and 43% weighed less than 4000 g at birth. The rate of instrument use was 41% , which is 4-fold higher than the 10% predicted for all vaginal deliveries in the United States. Posterior subluxation and glenoid version measurements in children with no finger movement at birth indicated a less severe shoulder deformity in comparison with those with finger movement. Conclusions. The average birth weight in this study was indistinguishable from the average birth weight reported for all brachial plexus injuries. Higher birth weight does not, therefore, affect the prognosis of brachial plexus injury. We found forceps/vacuum delivery to be an independent risk factor for OBPI, regardless of birth weight. Permanently injured patients with finger movement at birth develop more severe bony deformities of the shoulder than patients without finger movement.

Surgical normalization of the shoulder joint in obstetric brachial plexus injury

Obstetric brachial plexus injuries (OBPI) result in bony derangements that include posterior humeral head subluxation, glenoid retroversion, and joint incongruity. Often these deformities are accompanied by scapular hypoplasia, elevation, and rotation, which further exacerbate shoulder dysfunction. The purpose of the current study was to investigate the effects of triangle tilt surgery on glenohumeral joint anatomy in 100 OBPI patients. The triangle tilt surgery restores the distal acromioclavicular triangle from an abnormal superiorly angled position to a neutral position, thereby restoring normal glenohumeral anatomic relationships.Axial computed tomography and magnetic resonance images taken before and 12- to 38-months after surgery showed significant improvements in both posterior subluxation and glenoid version. Patients with complete posterior glenohumeral dislocation improved from 19% preoperatively, to 11% postoperatively. Glenoid shape was also improved, with 81% of patients classified as concave or flat after surgery compared with 53% before surgery.Triangle tilt surgery allows for both repositioning and remodeling of the glenohumeral joint. These anatomic improvements after triangle tilt surgery hold promise for improving shoulder function and quality of life for OBPI patients.

Glenohumeral dysplasia changes after tendon transfer surgery in children with birth brachial plexus injuries

BACKGROUND

This study hypothesizes that children with glenohumeral dysplasia secondary to birth brachial plexopathy treated with tendon transfer surgery at a younger age will show greater radiographic improvement than those treated at an older age.

METHODS

Twenty-six children treated with latissimus dorsi and teres major tendon transfer had preoperative and 1 year postoperative computed tomography (CT) scans at an average follow-up of 17 months (10 to 46 mo). Average age at surgery was 44 months (10 to 134 mo). CT scans were measured for glenoid version and percent humeral head anterior to the midscapular line (PHHA). Shoulders were classified as dislocated (PHHA 0%), subluxed (PHHA 1% to 35%), or normal positioning (>35%). Two age groups were compared: 24 months or less at the time of surgery (n=11); and greater than 2 years (n=15). Concomitant surgical techniques were also evaluated.

RESULTS

For the 11 children treated at 24 months of age or less, PHHA averaged 13% preoperatively (range: 0% to 54%) and postoperatively 42% (range: 25% to 51%); glenoid version averaged -25 degrees preoperatively (range: -36 to -11 degrees) and postoperatively -14 degrees (range: -31 to -2 degrees); and preoperatively 5 shoulders were dislocated, 5 subluxed, and 1 normal; whereas postoperatively 0 shoulders were dislocated, 2 subluxed, and 9 normally positioned. For the 15 children treated at greater than 2 years of age, PHHA averaged 30% preoperatively (range: 0% to 53%) and postoperatively 33% (range: 0% to 57%); glenoid version averaged -17 degrees preoperatively (range: -27 to -4 degrees) and postoperatively -16 degrees (range: -31 to -2 degrees); and preoperatively 2 shoulders were dislocated, 6 subluxed, and 7 normal; whereas postoperatively 2 shoulders were dislocated, 5 subluxed, and 8 normally positioned.

CONCLUSIONS

Eleven children treated at 24 months of age or less had significantly greater improvement in the CT scan radiographic measurements of glenohumeral dysplasia, than the 15 children treated at greater than 2 years of age. The effect of age had greater correlation with improvement than open reduction. For children undergoing tendon transfer for lack of active external rotation due to brachial plexus birth injury, improvement in glenohumeral dysplasia can be achieved if the surgery is performed before 2 years of age.

LEVEL OF EVIDENCE

Level IV, case controlled series.