Shoulder internal rotation contracture in brachial plexus birth injury: proximal or distal subscapularis release?

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.

Age Influence Upon Glenohumeral Remodeling After Shoulder Axial Rebalancing Surgery in Brachial Plexus Birth Injury

BACKGROUND

Shoulder rebalancing procedures have been proven to provide satisfactory functional improvements in patients with shoulder external rotation (ER) deficit due to brachial plexus birth injury (BPBI). However, the influence of age at the time of surgery on osteoarticular remodeling remains uncertain. The purposes of this retrospective case series were (1) to assess the age impact on glenohumeral remodeling and (2) to determine an age limit after which significant changes can no longer be expected.

METHODS

We reviewed preoperative and postoperative magnetic resonance imaging data of 49 children with BPBI who underwent a tendon transfer to reanimate active shoulder ER, with (n=41) or without (n=8) concomitant anterior shoulder release to restore passive shoulder ER, at a mean age of 72 ± 40 months (19;172). Mean radiographic follow-up was 35 ± 20 months (12;95). Univariate linear regressions were used to assess the influence of age at the time of surgery upon changes of glenoid version, glenoid shape, percentage of the humeral head anterior to the glenoid midline, and glenohumeral deformity. Beta coefficients with 95% CI were calculated.

RESULTS

Improvements of glenoid version, glenoid shape, percentage of the humeral head anterior and glenohumeral deformity significantly decreased by 0.19 degrees [CI=(-0.31; -0.06), P =0.0046], 0.02 grade [CI=(-0.04; -0.01), P =0.002], 0.12% [CI=(-0.21; -0.04), P =0.0076], and 0.01 grade [CI=(-0.02; -0.01), P =0.0078] per additional month of age at the time of surgery, respectively. The threshold of 5 years was identified as the age at the time of surgery after which significant remodeling no longer occurred. No significant postoperative changes were observed in patients without glenohumeral dysplasia on preoperative magnetic resonance imaging.

CONCLUSION

In the setting of BPBI-related glenohumeral dysplasia, the younger the surgical axial rebalancing of the shoulder, the greater the glenohumeral remodeling seems to be. Such procedure seems to be safe in patients without significant joint deformity on preoperative imaging.

LEVEL OF EVIDENCE

Therapeutic-Level IV.

Brachial Plexus Birth Injuries

Brachial plexus birth injuries (BPBIs) are typically traction type injuries to the newborn that occur during the delivery process. Although the incidence of these injuries has overall decreased from 1.5 to around 0.9 per 1000 live births in the United States over the past 2 decades, these injuries remain common, with incidence holding fairly steady from 2008 to 2014. Shoulder dystocia is the strongest identified risk factor, imparting a 100-fold greater risk. The newborn's shoulder is caught behind the mother's pubic bone, and traction performed on the child during delivery results in injury to the brachial plexus. Other risk factors associated with BPBI include macrosomia (birthweight > 4.5 kg), heavy for gestational age infants, birth hypoxia, gestational diabetes, and forceps or vacuum-assisted delivery. Breech presentation has also been described as a risk factor in the past, but there have been more recent data that challenge this association.

Change in shoulder external rotation strength and motion after lower trapezius transfer to the infraspinatus in children with obstetric brachial plexus palsy

PURPOSE

Quantifying changes in shoulder external rotation range of motion and strength after lower trapezius transfer in children with obstetric brachial plexus palsy (OBPP).

METHODS

This prospective study included five children with sequelae of OBPP, with a mean age of 6.4 years (range: 4-12 years) who underwent lower trapezius tendon transfer to restore active external rotation (ER) of the shoulder. Pre-operatively and at a 12-month follow-up assessment, we analyzed the passive and active shoulder ER, the modified Mallet score, and the shoulder rotator muscles strength using an isokinetic device.

RESULTS

Clinical parameters improved significantly after trapezius transfer pre-operative passive ER from -8° (range: -20-0°) to 37° (range: 15-50°) (p = 0.035), the modified Mallet score from 13 (range: 10-15) to 18 (range: 17-19) (p = 0.035). Strength testing revealed improved ER muscle strength in all five cases; the mean Peak Torque increased from 1.95 to 4.46 N·m, albeit non-significantly (p = 0.062). Two patients exhibited a winged scapula post-operatively.

CONCLUSION

Lower trapezius transfer seems encouraging to restore shoulder external rotation in OBPP children but with non-significant strength improvement.

TRIAL REGISTRATION

18/07/31/5783, December 22, 2018.