Quantification of humeral head deformity following neonatal brachial plexus palsy

Team Approach: Management of Brachial Plexus Birth Injury

Brachial plexus birth injury is an upper-extremity paralysis that occurs from a traction injury to the brachial plexus during birth. Approximately 10% to 30% of children with a brachial plexus birth injury have residual neurologic deficits with associated impact on upper-limb function. Management of brachial plexus birth injuries with a multidisciplinary team allows optimization of functional recovery while avoiding unnecessary intervention. Early occupational therapy should be initiated with a focus on range of motion and motor learning. The need for microsurgical reconstruction of the brachial plexus can be predicted based on early physical examination findings, and reconstruction is generally performed at 3 to 9 months of age. The majority of children with residual neurologic deficits develop associated glenohumeral dysplasia. These children may require secondary procedures, including botulinum toxin injection, subscapularis and pectoralis lengthening, shoulder capsular release, shoulder tendon transfer, and humeral osteotomy.

The effect of peripheral nervous system in growing bone biomechanics. An experimental study

Objective

There are several factors which affect bone growth. One of them is the peripheralnervous system whose effect on the biomechanics has not been extensively studied. The purpose of this study is to assess the effect of peripheral nervous system in bone biomechanics in an experimental rat model.

Materials & methods

27 male Wistar rats were used. In all animals, the roots of the right brachial plexus were dissected and after that the animals were divided into three groups A, B and C. The animals were sacrificed six, nine, and twelve months respectively after the denervation. Both humerus were resected and biomechanical analysis was performed.

Results

According to the findings of the present study the denervated bones sustain less loading before fracture and they become also more elastic. Additionally, in greater time after denervation plastic deformity is noticed.

Conclusion

Apart from structural changes, the peripheral nerves are responsible for biomechanic changes in the bones such the greater elasticity of the bone and the reduced strength.

Humeral Retroversion in Children with Shoulder Internal Rotation Contractures Secondary to Upper-Trunk Neonatal Brachial Plexus Palsy

BACKGROUND

The most common sequela of neonatal brachial plexus palsy is an internal rotation contracture of the shoulder that impairs function and leads to skeletal deformation of the glenohumeral joint. Treatment options include release, transfers, and humeral osteotomy, all ultimately striving for better function through increased external rotation. Prior studies have shown that neonatal brachial plexus palsy alters humeral retroversion but with conflicting findings. We studied retroversion in children with internal rotation contractures from neonatal brachial plexus palsy to clarify its effect on version and surgical planning.

METHODS

Bilateral shoulder and elbow magnetic resonance imaging scans of 21 children with neonatal brachial plexus palsy were retrospectively analyzed. Retroversion referenced to the transepicondylar line at the elbow was measured with respect to 2 different proximal reference axes, the longest diameter of an axial cut of the proximal part of the humerus (the skew axis) and the line perpendicular to the articular surface (the humeral center line). Glenoid version and glenohumeral morphology type (concentric glenoid, posterior-concentric glenoid, biconcave, or pseudoglenoid) were also determined. All geometric variables were assessed for correlation with patient age and the severity of the internal rotation contracture.

RESULTS

Retroversion on the involved side was decreased at 6° compared with 19° (p = 0.003), as measured between the skew axis and transepicondylar line. Retroversion referenced to the humeral center line was also decreased at -2° (anteversion) compared with 20° (p < 0.001). Patient age was inversely correlated with retroversion, but was only significant for the skew axis (r = -0.497, p = 0.022), decreasing in linear regression by 2.4° per year (p = 0.038). Humeral retroversion did not correlate with the severity of the internal rotation contracture, glenoid version, or glenoid morphology type.

CONCLUSIONS

Humeral retroversion is likely to be less on the affected side in children with internal rotation contractures from upper trunk neonatal brachial plexus palsy and merits consideration in surgical planning.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Imaging assessment of glenohumeral dysplasia secondary to brachial plexus birth palsy

Objective

To assess imaging parameters related to the morphology of the glenohumeral joint in children with unilateral brachial plexus birth palsy (BPBP), in comparison with those obtained for healthy shoulders.

Materials and Methods

We conducted a retrospective search for cases of unilateral BPBP diagnosed at our facility. Only patients with a clinical diagnosis of unilateral BPBP were included, and the final study sample consisted of 10 consecutive patients who were assessed with cross-sectional imaging. The glenoid version, the translation of the humeral head, and the degrees of glenohumeral dysplasia were assessed.

Results

The mean diameter of the affected humeral heads was 1.93 cm, compared with 2.33 cm for those of the normal limbs. In two cases, there was no significant posterior displacement of the humeral head, five cases showed posterior subluxation of the humeral head, and the remaining three cases showed total luxation of the humeral head. The mean glenoid version angle of the affected limbs (90-α) was -9.6º, versus +1.6º for the normal, contralateral limbs.

Conclusion

The main deformities found in this study were BPBP-associated retroversion of the glenoid cavity, developmental delay of the humeral head, and posterior translation of the humeral head.

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

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.

Three-Dimensional Magnetic Resonance Imaging of Glenohumeral Dysplasia in Neonatal Brachial Plexus Palsy

BACKGROUND

Existing quantitative measurements of glenohumeral dysplasia in children with unresolved neonatal brachial plexus palsy (NBPP) have been mostly limited to the axial plane. The purpose of this study was to describe the three-dimensional (3D) pathoanatomy of glenohumeral dysplasia using 3D magnetic resonance imaging (MRI) reformations.

METHODS

3D MRI reformations of the scapula, glenoid labrum, and proximal part of the humerus were created from a volume-acquisition proton-density-weighted MRI sequence of both the affected and the unaffected shoulder of seventeen children less than six years of age with unresolved NBPP who had not undergone shoulder surgery. Glenoid retroversion and posterior humeral head displacement were measured on axial 2D images. Humeral head displacement in all planes, labral circumference, glenoid retroversion, glenoid declination, and scapular morphometric values were measured on 3D reformations. Contiguity of the humeral head with the labrum and the shape of the glenoid were classified. Measurements were compared between the affected and unaffected sides.

RESULTS

On 3D evaluation, the humeral head was completely posteriorly translated in ten patients but was never outside the glenoid labrum. Instead, in these patients, the humeral head was eccentrically articulating with the dysplastic glenoid and was contained by a posteriorly elongated labrum. Glenoid dysplasia was not limited to the axial plane. Less declination of the glenoid in the coronal plane correlated with greater 3D glenoid retroversion. Glenoid retroversion resulted from underdevelopment of the posterior aspect of the glenoid rather than overdevelopment of the anterior aspect of the glenoid. 3D measurements of greater glenoid retroversion and less declination correlated with 2D measurements of glenoid retroversion and posterior humeral head displacement.

CONCLUSIONS

Posterior humeral head displacement in NBPP should not be considered a simple "dislocation." Glenohumeral dysplasia is not limited to the axial plane. Abnormal glenoid declination may have potential implications for the evaluation and treatment of shoulder weakness and contractures.

Prevalence of Posterior Shoulder Subluxation in Children With Neonatal Brachial Plexus Palsy After Early Full Passive Range of Motion Exercises

BACKGROUND

Children with neonatal brachial plexus palsy (NBPP) are often prescribed shoulder range of motion (ROM) exercises; however, the extent and timing of exercise implementation remains controversial in the context of shoulder joint integrity. The association of ROM exercises to delayed posterior shoulder subluxation (PSS) is unknown.

OBJECTIVE

To determine prevalence of PSS in children with NBPP who began full passive ROM exercises before 6 months of age, and characteristics associated with development or absence of PSS in children.

DESIGN

Cross-sectional study.

SETTING

Tertiary care NBPP referral center.

PARTICIPANTS

Forty-six children with NBPP, aged 24-57 months, who began full ROM exercises before 6 months of age.

METHODS

One radiologist conducted bilateral shoulder ultrasound (US) on each child to evaluate for PSS. One occupational therapist evaluated each child clinically for PSS using defined parameters without knowledge of US results.

MAIN OUTCOME MEASURES

By US, 20% of children had PSS; 46% had PSS by clinical examination. Shoulder active ROM limitations and history of shoulder surgery were associated with presence of PSS. Extent of NBPP was not associated with PSS.

RESULTS

Nine of 46 children (20%) met US criteria for PSS; α angle was 58° ± 21° (mean ± standard deviation [SD]). Twenty-one children (46%) met clinical criteria. Mean age at examination was 35 ± 10 months. Shoulder active ROM (P ≤ .004) was associated with PSS, whereas passive ROM was not (P ≥ .08). History of secondary shoulder surgery and primary nerve graft repair were associated with PSS (P = .04). Extent of NBPP by Narakas classification was not associated with PSS (P = .48).

CONCLUSIONS

Early use of full-arc passive ROM home exercise program is not associated with increased prevalence of PSS in children with NBPP compared to prevalence of PSS in published literature. We suggest careful clinical examination, based on defined criteria, provides a reasonable screening examination for evaluating PSS that can be confirmed by noninvasive US.

Three-dimensional humeral morphologic alterations and atrophy associated with obstetrical brachial plexus palsy

BACKGROUND

Obstetrical brachial plexus palsy (OBPP) is a common birth injury, resulting in severe functional losses. Yet, little is known about how OBPP affects the 3-dimensional (3D) humeral morphology. Thus, the purpose of this study was to measure the 3D humeral architecture in children with unilateral OBPP.

METHODS

Thirteen individuals (4 female and 9 male patients; mean age, 11.8 ± 3.3 years; mean Mallet score, 15.1 ± 3.0) participated in this institutional review board approved study. A 3D T1-weighted gradient-recalled echo magnetic resonance image set was acquired for both upper limbs (involved and noninvolved). Humeral size, version, and inclination were quantified from 3D humeral models derived from these images.

RESULTS

The involved humeral head was significantly less retroverted and in declination (medial humeral head pointed anteriorly and inferiorly) relative to the noninvolved side. Osseous atrophy was present in all 3 dimensions and affected the entire humerus. The inter-rater reliability was excellent (intraclass correlation coefficient, 0.96-1.00).

DISCUSSION

This study showed that both humeral atrophy and bone shape deformities associated with OBPP are not limited to the axial plane but are 3D phenomena. Incorporating information related to these multi-planar, 3D humeral deformities into surgical planning could potentially improve functional outcomes after surgery. The documented reduction in retroversion is an osseous adaptation, which may help maintain glenohumeral congruency by partially compensating for the internal rotation of the arm. The humeral head declination is a novel finding and may be an important factor to consider when one is developing OBPP management strategies because it has been shown to lead to significant supraspinatus inefficiencies and increased required elevation forces.

Geometry of the proximal humeral articular surface in young children: a study to define normal and analyze the dysplasia due to brachial plexus birth palsy

BACKGROUND

Little is known regarding the morphology of the proximal humerus in growing children. This study reports bilateral magnetic resonance imaging measurements in children with internal rotation contractures from birth palsy, hypothesizing that dysplasia alters normal humeral sphericity and symmetry.

METHODS

We studied 25 children with unilateral internal rotation contractures (mean age, 3.7 years) for humeral shape by bilateral magnetic resonance imaging studies at the mid-glenoid level. Local radii of curvature were compared for symmetry and orientation.

RESULTS

Neither side showed uniform radii (sphericity), but normal humeri showed symmetry lost in dysplasia. Internal rotation contractures were correlated with flattening of the anterior humeral head (P = .0002). All heads were flatter in the region of articular contact. The skew axis (the largest cross-sectional diameter of the proximal humerus) was collinear with the articular surface centerline in normal humeri, an alignment often lost with dysplasia, resulting in a skew axis angle. The severity of glenoid deformity correlated with progressive posterior displacement of the humeral head center (P < .0003).

CONCLUSION

The normal humeral articular surface in the young child is not spherical and is flatter in the middle than at the periphery but is symmetric about its central axis. Internal rotation contractures result in loss of this symmetry with characteristic flattening of the anterior humeral head and development of a skew axis angle.

CLINICAL RELEVANCE

Posterior displacement of the humeral head center of rotation beyond 50% of the calculated head radius warrants vigilance and possibly surgical intervention because there is a high likelihood for development of a pseudoglenoid.