Scapular Winging

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Winging is defined as a prominence of the medial or vertebral border of the scapula. Winging may or may not be symptomatic. The most common causes are long thoracic nerve palsy (serratus anterior weakness), usually from neuralgic amyotrophy. Not far behind, the second most common cause is spinal accessory nerve palsy (trapezius weakness), and this cause is frequently overlooked.

Aetiology and Classification

Fiddian et al in 1984 provided the following classification scheme.[1] This scheme can be useful in the absence of LTN or SAN palsy.[2]

  • Type I: Nerve - long thoracic nerve palsy and spinal accessory nerve palsy
  • Type II: Muscle - congenital absence of serratus anterior and/or trapezius, traumatic avulsion or surgical division of serratus anterior, facioscapulohumeral dystrophy, fibrosis of deltoid
  • Type III: Bone - scoliosis, craniocleidodysostosis, local skeletal lesions such as solitary exostoses or osteochondromata, malunion of fractures of the clavicle and acromion.
  • Type IV: Joint - abduction and internal rotation contractures secondary to degenerative or inflammatory joint disease or other, avascular necrosis of the humerus, chronic posterior shoulder dislocation
  • Voluntary: A fifth category designated by Seror et al, where other causes are excluded in bilateral dynamic winging.[2]

The causes of unilateral winged scapula in a study of 128 patients were[2]:

  • Long thoracic nerve palsy (54%), of which 87% were due to neuralgic amyotrophy
  • Spinal accessory nerve palsy (30%)
  • Both long thoracic and spinal accessory nerve palsy (4%)
  • Facioscapulohumeral dystrophy (4%)
  • Orthopaedic causes (9%)
  • Voluntary (5%)
  • No definitive cause (2%)

Neuralgic amyotrophy is a common underlying cause. This is an acute painful monophasic neuropathy with unique or multiple nerve lesions. Clinical features are weakness, amyotrophy, and sensory loss in an asymmetric and patchy distribution, mainly involving the upper limbs. Cervical MRI is normal.[2]

Clinical Patterns

Winging of the scapula is either static or dynamic.

  • Static winging is due to a fixed deformity of the shoulder girdle, spine or ribs. This is usually present at rest but can be accentuated by certain passive movements and eliminated by others. Active or resisted shoulder movements don't usually accentuate the deformity and may eliminate it.
  • Dynamic winging is due to a neuromuscular disorder, is visible with active and resisted movements, and is absent at rest. it is rarely accentuated by passive shoulder movement with a fully relaxed shoulder girdle.
Clinical patterns for differentiating between long thoracic nerve and spinal accessory nerve palsies[2]
Long Thoracic Nerve Palsy Spinal Accessory Nerve Palsy
Classical physical signs
Muscle palsy and signs on inspection Serratus anterior atrophy of digitations Trapezius atrophy of lower and upper fibres
Side involved Right side is 88% Random
Position of scapula when winged Medial, near the spine Lateral, away from the spine
Movement that brings on or enhances winging Forward flexion with pushing on a wall or pull ups Abduction with external rotation against resistance
Additional physical signs
Ropelike lower trapezius Raised by the medial margin of scapula and descends toward the lower thoracic vertebrae. Best seen with anterior elevation of 95-120° Never seen because the lower trapezius is atrophied
Ropelike rhomboid major Never seen because the rhomboids are masked by the normal trapezius Rises from the inferior angle of the scapula towards the upper thoracic vertebrae, best seen at rest or near rest
Abrupt sliding of the scapula during lateral elevation Never seen Occurs with lateral elevation of at least°

Definitive diagnosis requires electrophysiology studies.

References

  1. Fiddian NJ, King RJ. The winged scapula. Clin Orthop Relat Res. 1984 May;(185):228-36. PMID: 6705385. Full Text
  2. 2.0 2.1 2.2 2.3 2.4 Seror P, Lenglet T, Nguyen C, Ouaknine M, Lefevre-Colau MM. Unilateral winged scapula: Clinical and electrodiagnostic experience with 128 cases, with special attention to long thoracic nerve palsy. Muscle Nerve. 2018 Jun;57(6):913-920. doi: 10.1002/mus.26059. Epub 2018 Feb 24. PMID: 29314072.