Introduction 2 3 9 14 17 12 1 14 Fig. 1 At rest the child is noted to exhibit an internal rotation posture at the shoulder with elbow flexion and pronation of the forearm. There is apparent shortening of the arm  8 11 12 17 In the current study, we describe dysplasia and malposition of the entire scapula in obstetric brachial plexus palsy patients. We introduce a classification of this deformity which we term collectively Scapular Hypoplasia, Elevation and Rotation (SHEAR). Methods Patients A total of 30 obstetric brachial plexus palsy patients with glenohumeral internal rotation were evaluated in the past 6 months. We reviewed the clinical data on these patients and diagnosed and classified the scapular elevation according to the results of clinical examination and analysis. There were 10 boys and 20 girls ranging in age from 10 months to 10.6 years. Three of the children had not undergone any surgery. Twenty-four of the children had undergone latissimus dorsi and teres major muscle transfer, subscapularis, pectoralis major and minor contracture releases and axillary nerve decompression and neurolysis for correction of abduction at our institute in the past. Twelve of the latter group and one that had not undergone the aforementioned procedure had undergone primary neurological repair surgery. Measurements Transverse CT section and three-dimensional reconstructions of bilateral computerized tomograms (3D-CT) were used in the evaluation process. Trunk anterior and trunk posterior views of the whole shoulder girdle as well as superior trunk outlet and scapular posterior and medial views were examined. The contralateral scapulae were assessed for comparison. H W w 2 Fig. 2 a left W w acr H right b A H α c Line 1 line 2 line 3 γ δ d e θ θ  A H 2 α 2 γ δ 2 2 The total area of the scapula was calculated on the scapular posterior view. The area of the scapula visible on the anterior view above the clavicle with reference to the contralateral side was measured on the trunk anterior view. For distance and area measurements, graphic software (Universal Desktop Ruler, AVPSoft.com) was used. 5 θ 2 2 Both the affected and contralateral sides were assessed and the values discussed take into account comparison between sides unless specifically indicated. Statistics t P P Results 1 r r r r r r r r r Table 1 Details of the computed tomography data on the patients  Affected Contralateral Affected to contralateral P r a Mean Range Mean Range Mean Range Hypoplasia Acromion as percentage of width W 35.6 ± 5.6% 24.4 to 48.9% 32.4 ± 2.4% 27.8 to 37.5% 1.10 ± 0.17 0.70 to 1.58 <0.000 0.57 Acromion as percentage of height H 36.0 ± 6.6% 22.4 to 55.6% 30.5 ± 3.0% 24.4 to 35.7% 1.19 ± 0.24 0.79 to 1.73 <0.000 0.71 Affected acromion/control acromion acr/acr     1.04 ± 0.14 0.73 to 1.28 NS 0.56 Percent scapular area visible above clavicle     17.76 ± 14.35% 0.61 to 53.98%   Percent ratio affected to contralateral scapular area     86.0 ± 6.4% 73.1 to 103.3%  −0.57 Affected to contralateral height ratio H H    0.89 ± 0.10 0.69 to 1.11 <0.05 −0.55 Affected to contralateral width ratio W W    0.95 ± 0.07 0.78 to 1.09 NS −0.14 Height to scapular body width H w 1.38 ± 0.20 0.95 to 1.81 1.40 ± 0.15 1.03 to 1.70 1.00 ± 0.13 0.80 to 1.30 NS −0.30 Affected to contralateral scapular body width w w    0.90 ± 0.07 0.76 to 1.00 <0.05 −0.35 Height to total width ratio H W 1.00 ± 0.13 0.68 to 1.26 1.07 ± 0.10 0.91 to 1.30 0.94 ± 0.13 0.69 to 1.17 <0.05 −0.35 Elevation Percent vertical displacement A H    −1.6 ± 9.33% −20.2 to 18.8%  −0.03 Rotation Downward/Upward displacement α 59.7° ± 13.54 35° to 83° 83.9° ± 10.12 67° to 111° −24.2 ± 10.98 −41 to −6 <0.000 −0.65 Internal/External displacement ^ζ −35.2° ± 8.50 18° to 55° 40.4° ± 4.93 30.5° to 49° −6.5° ± 7.92 −20.5° to 17° NS −0.22 Anterior/Posterior displacement ^ϕ 35.4° ± 7.93 20° to 48° 43.2° ± 8.02 25° to 54° −8.1° ± 4.89 −18° to 4° <0.05 0.29 Superior scapular angle γ 45.6° ± 11.50 20° to 67° 58.3° ± 7.36 44° to 81° −12.8° ± 13.09 −42° to 11° <0.000 −0.84 Inferior scapular angle δ 31.1° ± 16.51 −2° to 67° 9.7° ± 7.70 −3° to 27° 21.4° ± 17.72 −9° to 62° <0.000 0.83 Percent subluxation LM/LN × 100 25.7 ± 20.75% −27.7 to 53.0% 49.0 ± 3.51% 41.0 to 56.2 −23.3 ± 21.21 −76.0 to 4.6 <0.000 −0.80 Glenoscapular angle θ −20.4° ± 11.34 −45° to 0° −2.9° ± 3.74 −11° to 5° −17.6° ± 10.88 −43° to 1° <0.000 −0.51 2 a Age did not significantly correlate with any of the parameters measured. Vertical displacement was noted to be either superior (15 patients) or inferior (15 patients) and did not significantly correlate with any of the parameters measured. r r Internal/external rotation did not significantly correlate with any of the parameters measured although only three patients had external rotation and two no rotation. Anterior/posterior rotation did not correlate significantly with any of the parameters measured although only one patient had posterior rotation and one no rotation. r r r r r r r r r r 3 Fig. 3 The different SHEAR stages of scapular deformity as determined by three dimensional computer tomography. In SHEAR Grade 0 less than 2% of the scapula, less than 20% of the superior border and less than 6.5% of the medial border are visible above the clavicle. In SHEAR Grade 1 2–3.6% of the scapular area, 20–45% of the superior border and 6.5–16.5% of the medial border are visible over the clavicle. In SHEAR Grade 2 3.6–20% of the scapular area, 45–58% of the superior border and 16.5–28% of the medial border are visible above the clavicle. In SHEAR Grade 3 20–45% of the scapula, 58–68% of the superior border and 28–50% of the medial border are visible over the scapula. In SHEAR Grade 4 more than 42% of the area of the scapula, more than 68.5% of the superior border and more than 50% of the medial border are visible over the scapula  Discussion The position of the affected scapula did not follow the symptoms and characteristics of Sprengel’s deformity with congenital origin of scapular elevation. The hypoplasia and positioning of the scapula result from the brachial plexus injury and the apparent elevation is the result of downward rotation about an axis perpendicular to the scapular plane. 8 11 7 P r r r r r 4 8 11 r r r r r 1 13 17 13 17 6 10 15 15 17 2 2 16 16 Conclusion Scapular deformities common to the population of obstetric brachial plexus palsy patients due to muscular imbalances resulting from residual neurological deficit can be diagnosed and classified using the SHEAR classification and enable objective evaluation of the bony deformity and its severity as guide for treatment.