Three dimensionality of gleno‐humeral deformities in obstetrical brachial plexus palsy

Abstract

The primary objective of this study was to test the hypothesis that gleno-humeral deformity in children and adolescent with obstetrical brachial plexus palsy is three-dimensional (3D). The study also compared the metrological properties of typical two-dimensional gleno-humeral measures to the newly developed 3D measures. Thirteen individuals (age = 11.8 ± 3.3 years) with obstetrical brachial plexus palsy participated in this IRB-approved study. 3D axial magnetic resonance images were acquired for both shoulders. Glenoid and humeral models were created in order to quantify 3D glenoid version, humeral head migration, and glenoid concavity. Two-dimensional (2D) measures were acquired as recommended in the literature. All measures were completed by two observers in this observer-blind study. Compared to the non-involved side, the glenoid was more retroverted (7.91°, p = 0.003) and inferiorly oriented (7.28°, p = 0.009). The humeral head was migrated more posteriorly (5.54 mm, p = 0.007), inferiorly (−3.96 mm, p = 0.013), and medially (−3.63 mm, p = 0.002). Eleven of the 13 glenoids were concave, based on the 3D glenoid models. The concurrent validity between three-and 2D measures were highly dependent of the parameter measured, the slice level used for the 2D analysis, and the presence/absence of pathology (0.63 <r <0.91). The standard error of measurement for the 2D anterior–posterior version (>3°) was larger than that for the 3D measure of version (<1°) on the involved side. This study clearly demonstrated that the gleno-humeral deformation in obstetrical brachial plexus palsy is 3D, emphasizing the need for 3D subject specific gleno-humeral shape analysis for follow-up and treatment plans in children with obstetrical brachial plexus palsy.

Shoulder muscle atrophy and its relation to strength loss in obstetrical brachial plexus palsy

“…Muscles with a moment arm greater than 6 mm in a specific torque direction were considered as contributors to that torque. This qualitative cut-off was slightly higher than our previous study 21 due to the potential alteration in moment arms secondary to the bone deformities and humeral head migration in OBPP 22 . This resulted in the entire deltoid being considered an abductor, its anterior segment a flexor, and its posterior segment an extensor 26 .…”

“…Data from an ongoing IRB (National Institute of Child Health and Human Development, intramural, MD, USA) approved study 4,22,21,23 formed the basis of this case-controlled study. Sixteen children/adolescents with unilateral OBPP were recruited as a sample of convenience.…”

“…However, the in vivo relationship between muscle volume and torque has not been established in children with OBPP. A direct relationship between muscle volume and strength may not exist in these children, as other factors, such as glenohumeral deformity 22 or fatty infiltration 5 , may alter the relationship.…”

Relationship between glenoid deformity and gait characteristics in a rat model of neonatal brachial plexus injury

“…Though glenoid version angle is the most common clinical measure of glenoid deformity in NBPI, glenoid deformity may not be limited to the axial plane. Two recent studies that evaluated the three‐dimensional morphology of the glenoid found that the glenoid on the affected side was significantly more retroverted and declined in children with NBPI . Another study found that glenoid retroversion deformity severity was negatively correlated with glenoid declination deformity severity .…”

“…Estimates of incomplete neurological recovery range widely, but were reported to be as high as 27% in one prospective large‐scale study . Infants without full neurological recovery predominantly display glenoid retroversion, which may also be accompanied by posterior humeral head subluxation, malformation of the humeral head and glenoid, and glenoid declination . Rotator cuff muscular imbalance and internal rotation contracture is also attributed to NBPI, with associated subscapularis shortening and stiffening, and weakening or paralysis of the infraspinatus and supraspinatus .…”