Article

Quantification of humeral head deformity following neonatal brachial plexus palsy.

Department of Radiology (B.D.R. and T.L.), Division of Biostatistics and Epidemiology (S.R.S.), and Division of Pediatric Orthopaedic Surgery (R.C. and W.C.L.), Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229. E-mail address for T. Laor: .
The Journal of Bone and Joint Surgery (Impact Factor: 4.31). 09/2012; 94(18):e1361-8. DOI: 10.2106/JBJS.K.00540
Source: PubMed

ABSTRACT Neonatal brachial plexus palsy frequently leads to glenohumeral dysplasia if neurological recovery is incomplete. Although glenoid retroversion and glenohumeral subluxation have been well characterized, humeral head deformity has not previously been quantified. Nonetheless, humeral head flattening is described as a contraindication to joint contracture release and external rotation tendon transfers. This study describes a novel technique for objectively quantifying humeral head deformity with use of magnetic resonance (MR) imaging and correlates the humeral head deformity with clinical and radiographic outcomes following joint rebalancing surgery.
Magnetic resonance images of thirty-two children (age, 0.7 to 11.5 years) with neonatal brachial plexus palsy were retrospectively reviewed. Passive shoulder external rotation and Mallet scores were reviewed before joint rebalancing surgery and at a minimum clinical follow-up interval of two years. The humeral head skewness ratio on preoperative and postoperative axial MR images was defined as the ratio of anterior to posterior humeral head area, and this ratio was compared between affected and unaffected shoulders and with the glenoid version angle, posterior subluxation of the humeral head, and clinical parameters before and after surgery with use of paired t tests and Spearman correlation. Intraobserver and interobserver reliability of MR image measurements was determined.
Measurements of the skewness ratio on the affected side had moderate to substantial intraobserver reliability (0.53 to 0.72) and substantial interobserver reliability (0.65 to 0.71). Preoperatively, the skewness ratio of the affected humeral head (mean, 0.76; range, 0.54 to 1.03) differed significantly from the ratio in the contralateral shoulder (p < 0.05) and was significantly associated with the glenoid version angle (p < 0.05) and posterior subluxation of the humeral head (p < 0.05). Remodeling of the affected humeral head was observed postoperatively, with a significant improvement in the skewness ratio (p < 0.05). However, there were no significant correlations between the preoperative skewness ratio and postoperative clinical outcomes.
Humeral head deformity in neonatal brachial plexus palsy correlated with other measures of glenohumeral dysplasia and could be reliably and objectively quantified on MR imaging with use of the skewness ratio. The humeral head deformity can remodel following joint rebalancing surgery, and such a deformity alone does not preclude a successful outcome after surgical attempts to restore glenohumeral congruity.
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    ABSTRACT: 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. 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. 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). 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.
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