Spot diagnosis
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winged scapula child causes serratus anterior palsy
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Spot Diagnosis: Winged Scapula (Scapula Alata)
The image shows a child with the left scapula's medial (vertebral) border prominently protruding away from the chest wall, forming a characteristic "wing" - this is Winged Scapula (Scapula Alata).
Pathophysiology
The scapula is normally held flat against the thoracic wall by the serratus anterior muscle. This muscle is innervated by the long thoracic nerve (C5, C6, C7). When this muscle is weak or paralyzed, the medial border of the scapula loses its anchor against the rib cage and protrudes posteriorly - most prominently in the lower two-thirds of the scapula.
Key Clinical Features
- Scapula medial border juts out, especially when the patient pushes arms forward against a wall or holds arms outstretched
- Weakness of shoulder elevation above head
- Fatigue with overhead activities
- May have shoulder/neck pain radiating to upper arm (in traumatic cases)
Causes
| Cause | Notes |
|---|---|
| Long thoracic nerve palsy | Most common - serratus anterior paralysis |
| Spinal accessory nerve palsy | Trapezius weakness - less medial, more lateral winging |
| Facioscapulohumeral muscular dystrophy (FSHD) | Bilateral, progressive - consider in children |
| Neuralgic amyotrophy (Parsonage-Turner syndrome) | Preceded by severe shoulder pain |
| Trauma / rucksack paralysis | Pressure on shoulder |
| Iatrogenic | Post-mastectomy, thoracotomy, rib resection |
In a pediatric patient, FSHD and long thoracic nerve injury (traumatic or viral post-infectious neuropathy) should be high on the differential.
How to Confirm
- Ask the child to push both hands against a wall - winging becomes exaggerated
- Check for bilateral involvement (suggests FSHD)
- EMG/NCS - to assess long thoracic nerve and serratus anterior
- Genetic testing if FSHD suspected
- CK levels (elevated in muscular dystrophy)
Management
- Most long thoracic nerve palsies are self-limiting - resolve within 12-18 months
- Physiotherapy - scapular stabilization exercises
- Surgery (pectoralis major transfer or scapulothoracic fusion) only for chronic, functionally disabling cases unresponsive to conservative treatment
Localization in Clinical Neurology, 8e - "Long thoracic nerve palsy causes winged scapula most frequently due to trauma, heavy shoulder loads, or neuralgic amyotrophy. The winging is most pronounced in the lower two-thirds of the scapula."
It's not scapula, posterior ribs are malformed, hump is of unilateral ribs
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unilateral posterior rib hump child diagnosis causes
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Revised Diagnosis: Scoliosis with Rib Hump (Posterior Rib Prominence)
The unilateral hump formed by the posterior ribs in a child is the classic sign of structural scoliosis - specifically idiopathic thoracic scoliosis with vertebral rotation.
Why Ribs Form a Hump in Scoliosis
In structural scoliosis, the spine does not simply curve sideways - it also rotates. The vertebral bodies rotate toward the convex side of the curve, and since the ribs attach to the vertebrae, they are dragged along:
- Ribs on the convex side are pushed posteriorly → forming the rib hump
- Ribs on the concave side are pushed anteriorly → causing anterior chest wall prominence on the opposite side
The hump you see is made of the malformed/displaced posterior ribs on the convex side of the thoracic curve.
Confirmatory Test: Adam's Forward Bend Test
Ask the child to bend forward at the waist with knees straight and arms hanging down:
- Structural scoliosis: the rib hump increases as the child bends forward (rotatory deformity)
- Functional scoliosis: the spine straightens, rib hump disappears (no true rotation)
A scoliometer placed at the apex measures the angle of trunk rotation - ≥7 degrees is the threshold for referral for X-ray.
Differential Diagnosis in This Child
| Diagnosis | Features |
|---|---|
| Idiopathic scoliosis (most likely) | Most common in girls 10-16 yrs; painless; no neurological deficit |
| Congenital scoliosis | Vertebral malformation (hemivertebra, bar) - unilateral rib malformation can be primary |
| Neuromuscular scoliosis | CP, muscular dystrophy, spina bifida |
| Syndromic | Neurofibromatosis (look for café-au-lait spots), Marfan, Ehlers-Danlos |
Given the unilateral rib malformation you describe (not just rotation), congenital scoliosis with a structural rib anomaly (fused ribs, rib synostosis, or absent ribs) should also be strongly considered.
Next Steps
- Standing PA + lateral spine X-ray (full-length) - measure Cobb angle, look for vertebral anomalies
- Look for café-au-lait spots, axillary freckling (neurofibromatosis)
- MRI spine - if congenital anomaly or neurological signs present
- Refer to pediatric orthopedic surgery
Bailey & Love's Surgery, 28e: "A rib hump will increase in size on the thoracic convex side as the patient bends forward - this is diagnostic of idiopathic thoracic scoliosis (rotatory deformity)."
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