The Unstable Scapula
Two Patterns
Critical Must-Knows
- Most winging is neurogenic: serratus anterior (medial) or trapezius (lateral).
- The long thoracic nerve comes from roots C5, C6 and C7 (remember Bell - C5/6/7).
- Wall push-up test brings out medial winging; resisted abduction brings out lateral winging.
- Most neurogenic palsy recovers spontaneously - give conservative care for around 12 to 24 months before salvage surgery.
Clinical Pearls
- "Painful onset with patchy shoulder-girdle weakness suggests neuralgic amyotrophy (Parsonage-Turner).
- "Pectoralis major (sternal head) transfer is the salvage of choice for fixed serratus anterior palsy.
- "Eden-Lange transfer (levator scapulae + both rhomboids) is the salvage for fixed trapezius palsy.
Clinical Imaging
Exam Essentials
Medial vs Lateral
Direction tells you the nerve Medial winging (scapula towards the spine, worse on forward push) = serratus anterior / long thoracic nerve. Lateral winging (scapula slides out and droops, worse on abduction) = trapezius / spinal accessory nerve.
Iatrogenic Trap
The neck biopsy story A drooping shoulder and winging after a lymph node biopsy or neck dissection is spinal accessory nerve injury until proven otherwise. Examine the posterior triangle scar.
Memory Aids
Bell 567Long Thoracic Nerve Roots
| 5 | C5 Root contribution from C5. |
| 6 | C6 Root contribution from C6. |
| 7 | C7 Root contribution from C7. |
| 5 | C5 Root contribution from C5. |
| 6 | C6 Root contribution from C6. |
| 7 | C7 Root contribution from C7. |
Hook:The nerve of Bell rings at 5-6-7: C5, C6, C7 raise your arm above 7 (heaven).
TRAPCauses of Winging
| T | Trauma / Traction Stretch of long thoracic nerve, blunt shoulder trauma, muscle avulsion. |
| R | Rucksack / Repetitive Backpack palsy and repetitive overhead sport (archery, tennis, swimming). |
| A | Amyotrophy (neuralgic) Parsonage-Turner syndrome - painful, often post-viral or post-vaccine. |
| P | Postsurgical / Palsy Iatrogenic spinal accessory nerve injury (neck biopsy), axillary node clearance. |
| T | Trauma / Traction Stretch of long thoracic nerve, blunt shoulder trauma, muscle avulsion. | A | Amyotrophy (neuralgic) Parsonage-Turner syndrome - painful, often post-viral or post-vaccine. |
| R | Rucksack / Repetitive Backpack palsy and repetitive overhead sport (archery, tennis, swimming). | P | Postsurgical / Palsy Iatrogenic spinal accessory nerve injury (neck biopsy), axillary node clearance. |
Hook:A heavy TRAP on the shoulder wings the scapula.
LRREden-Lange Transfer
| L | Levator scapulae Transferred laterally onto the scapular spine (replaces upper trapezius). |
| R | Rhomboid minor Transferred laterally (replaces middle trapezius). |
| R | Rhomboid major Transferred laterally onto the infraspinous body (replaces lower trapezius). |
| L | Levator scapulae Transferred laterally onto the scapular spine (replaces upper trapezius). |
| R | Rhomboid minor Transferred laterally (replaces middle trapezius). |
| R | Rhomboid major Transferred laterally onto the infraspinous body (replaces lower trapezius). |
Hook:LRR rebuilds the three pulls of the lost trapezius for fixed lateral winging.
Overview
Definition
Scapular winging: abnormal protrusion of the scapula away from the chest wall because the muscles that hold it flat and rotate it (mainly serratus anterior and trapezius) are weak, detached, or imbalanced.
The scapula is the stable platform from which the arm works. Normal overhead elevation needs smooth scapulothoracic rhythm - the scapula rotating upward as the arm rises. If a key stabiliser fails, the scapula lifts off the chest wall, the shoulder loses power and elevation, and the patient develops pain and fatigue. The two classic neurogenic patterns are medial winging (serratus anterior) and lateral winging (trapezius). Less commonly, direct muscle avulsion or rhomboid (dorsal scapular nerve) weakness is responsible.
According to PubMed, the most common causes are dysfunction of the serratus anterior from long thoracic nerve injury (medial winging) or dysfunction of the trapezius from spinal accessory nerve injury (lateral winging), but acute traumatic tears of serratus anterior, trapezius and rhomboids are under-recognised causes (Didesch and Tang, 2018; DOI).
Anatomy
Serratus Anterior and the Long Thoracic Nerve
- Origin/insertion: Arises from the upper 8 or 9 ribs, wraps around the chest wall, and inserts on the deep surface of the medial scapular border.
- Action: Protracts the scapula and, crucially, produces upward rotation so the glenoid faces up for overhead reach. It also holds the medial border flat against the thorax.
- Nerve: Long thoracic nerve (the nerve of Bell), roots C5, C6, C7. It runs superficially on the surface of serratus anterior, making it vulnerable to traction and direct trauma.
- Failure: Loss produces medial winging - the medial border lifts off and drifts towards the spine, and forward elevation is limited and weak.
Pathophysiology
How the Nerves Get Injured
Long thoracic nerve (medial winging):
- Traction (sudden depression of the shoulder, sport, heavy lifting) and the long superficial course make it vulnerable.
- Compression by a backpack ("rucksack palsy").
- Often there is no clear injury - an inflammatory neuritis (neuralgic amyotrophy) is increasingly recognised.
Spinal accessory nerve (lateral winging):
- Most commonly iatrogenic - cervical lymph node biopsy, excision in the posterior triangle, or neck dissection.
- Penetrating or blunt trauma to the posterior triangle.
According to PubMed, the spinal accessory nerve's superficial course in the posterior cervical triangle makes it susceptible to injury, and iatrogenic injury after a surgical procedure is one of the most common causes of trapezius palsy (Wiater and Bigliani, 1999).
Classification
Medial vs Lateral (the working classification)
- Medial (dynamic) winging: Serratus anterior palsy. Inferior angle rotates towards the midline; winging worst on forward flexion / wall push-up.
- Lateral winging: Trapezius palsy. Scapula translates laterally, inferior angle rotates outward, shoulder droops; winging worst on abduction.
- This direction-based split is the most useful clinically because it points straight to the nerve.
Clinical Assessment
History: Ask about onset (sudden painful onset suggests neuralgic amyotrophy), recent neck surgery or biopsy (accessory nerve), trauma, backpack use, and sport (archery, tennis, swimming, weightlifting). Ask what the patient cannot do - overhead work and pushing are typically affected.
Inspection: Look from behind with the patient relaxed and then provoke. Note a drooping shoulder and asymmetric neckline (trapezius) versus a flat-resting scapula that wings on push (serratus).
Provocation tests:
- Wall push-up test: The patient pushes against a wall - medial winging of serratus palsy is exaggerated.
- Forward flexion / arm raise: Brings out medial (serratus) winging.
- Resisted abduction / shoulder shrug: Brings out lateral (trapezius) winging and reveals trapezius weakness.
| Feature | Medial Winging (Serratus) | Lateral Winging (Trapezius) |
|---|---|---|
| Nerve | Long thoracic (C5-7) | Spinal accessory (CN XI) |
| Scapular position | Medial border up, towards spine | Translated lateral, shoulder droops |
| Worse on | Forward flexion / wall push-up | Abduction / shrug |
| Typical cause | Traction, sport, neuritis | Neck biopsy / dissection (iatrogenic) |
Investigations
Electrodiagnostic studies (the key test):
- EMG / nerve conduction studies confirm the diagnosis, localise the lesion (serratus vs trapezius vs rhomboids), grade severity, and - on serial testing - detect reinnervation, which guides timing of surgery.
- Needle EMG of serratus anterior or trapezius shows denervation in neurogenic palsy.
Imaging:
- Plain radiographs / CT: Exclude bony causes (osteochondroma, malunion) and pseudo-winging.
- MRI: Useful for muscle atrophy, mass lesions, and increasingly for nerve pathology - high-resolution imaging and ultrasound can show hourglass-like constrictions in neuralgic amyotrophy.
- High-resolution ultrasound: Dynamic assessment of the nerve and muscle; identifies constrictions in neuralgic amyotrophy.
According to PubMed, improved MRI and high-resolution ultrasound have identified pathognomonic hourglass-like nerve constrictions in neuralgic amyotrophy, which has shifted the condition from a purely clinical diagnosis towards imaging-guided diagnosis and, in selected cases, surgery (Gstoettner et al., 2020; DOI).
Differential Diagnosis
The classic trap is calling every protruding scapula "serratus palsy". Always decide the direction of winging first, then look for the cause.
| Condition | Distinguishing Feature | Key Test |
|---|---|---|
| Serratus anterior palsy | Medial winging, worse on push-up, inferior angle to midline | EMG serratus; long thoracic nerve |
| Trapezius palsy | Lateral winging, drooping shoulder, neck scar | EMG trapezius; accessory nerve |
| Rhomboid (dorsal scapular) palsy | Subtle medial winging, inferior angle rotated laterally | EMG rhomboids |
| Neuralgic amyotrophy | Severe pain first, then patchy weakness, often bilateral/post-viral | MRI/US nerve constrictions; EMG |
| FSHD muscular dystrophy | Bilateral, facial weakness, family history, young patient | Genetic testing, CK, EMG |
| Snapping scapula / osteochondroma | Painful crepitus, pseudo-winging, no denervation | CT scapula (bony lesion) |
| Voluntary / habitual winging | Reproducible on demand, painless, normal nerves | Normal EMG; psychological assessment |
The Examiner's Favourite Trap
Bilateral, symmetric winging with facial weakness in a young patient is FSHD, not a nerve injury. And a painful, sudden-onset palsy that does not respect a single nerve - especially after a viral illness or vaccination - is neuralgic amyotrophy, which is treated very differently from a simple traction palsy.
Management Algorithm
Conservative Management (first line for neurogenic palsy)
- Why: Most neurogenic winging recovers spontaneously - the traditional teaching is recovery within around 2 years for long thoracic nerve palsy.
- What: Physiotherapy (scapular stabiliser strengthening, range of motion to avoid stiffness), activity modification, and analgesia.
- Bracing: Scapulothoracic orthoses are described but are often poorly tolerated.
- Duration: Continue for roughly 12 to 24 months with serial clinical and EMG review for reinnervation before considering salvage.
According to PubMed, most patients with serratus palsy regain function with conservative treatment, although recovery may take up to 2 years, and bracing is often poorly tolerated (Wiater and Flatow, 1999).
Pick the salvage by the pattern
Medial winging that will not recover to pectoralis major transfer. Lateral winging that will not recover to Eden-Lange. Dystrophic muscle (FSHD) to scapulothoracic fusion.
Surgical Technique
Pectoralis Major Transfer (for serratus palsy)
- Goal: Replace the lost upward-rotation and stabilising pull of serratus anterior.
- Principle: The sternal head of pectoralis major is mobilised and transferred to the inferior angle of the scapula, usually lengthened with an autograft (fascia lata, hamstring) to reach.
- Steps:
- Two-incision approach (anterior axillary fold and over the inferior scapular angle).
- Harvest the sternal head of pectoralis major.
- Lengthen with fascial/tendon graft if needed.
- Pass deep to the chest wall soft tissue to the inferior angle.
- Fix to the scapula and tension with the arm at the side.
According to PubMed, transfer of the sternal head of pectoralis major to the inferior angle of the scapula reinforced with fascia or tendon autograft consistently improves function, eliminates winging and reduces pain (Wiater and Flatow, 1999; Galano et al., 2008; DOI).
Complications
Missed or Wrong Diagnosis
- Calling lateral (trapezius) winging "serratus palsy" sends the surgeon to the wrong operation.
- Missing FSHD or neuralgic amyotrophy leads to inappropriate early surgery.
Always confirm the direction of winging and back it with EMG.
Postoperative Care
- Sling/abduction support after tendon transfer to protect the repair.
- Gentle passive range of motion to avoid stiffness; no active loading of the transfer.
- Begin active scapular control and assisted elevation.
- Start retraining the transferred muscle to fire in its new role.
- Progressive strengthening and return to function.
- Heavy lifting and sport deferred until the transfer is strong and winging is controlled.
Clinical Relevance and Prognosis
- Spontaneous recovery is common in neurogenic palsy - the natural history justifies patience before salvage surgery.
- But not everyone recovers fully: residual winging, weakness and fatigability persist in a meaningful proportion, which is why a proactive nerve-surgery approach is gaining ground for persistent cases.
- Timing is everything for nerve surgery: the best outcomes for neurolysis or repair come within around 12 months.
- Salvage works: pectoralis transfer (serratus) and Eden-Lange (trapezius) reliably reduce pain and winging and improve function in fixed palsy.
According to PubMed, the older view that almost all long thoracic nerve palsies recover within 2 years is an oversimplification - a significant percentage retain residual winging and weakness, and decompression beyond 12 months can still yield satisfactory results (Wu and Ng, 2023; DOI).
Evidence Base
Anatomy, Etiology, and Management of Scapular Winging (Review)
- Comprehensive review of anatomy, etiology, evaluation and treatment of scapular winging
- Most common causes: serratus anterior dysfunction from long thoracic nerve injury (medial winging) and trapezius dysfunction from spinal accessory nerve injury (lateral winging)
- Acute traumatic tears of serratus anterior, trapezius and rhomboids are under-recognised causes
- Distinguishes management of neurogenic winging from traumatic muscular detachment
Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
Scenario 1: The Tennis Player Who Cannot Reach
"A 28-year-old recreational tennis player has aching and weakness reaching overhead for 3 months. From behind, the right scapula sits flat at rest but the medial border lifts off and drifts towards the spine when he pushes against the wall."
Scenario 2: After the Neck Biopsy
"A 45-year-old woman has a drooping right shoulder, pain and difficulty abducting the arm six months after an excisional lymph node biopsy in the posterior triangle of the neck. The scapula sits laterally and droops; winging worsens on abduction."
Scenario 3: The Young Man With Bilateral Winging
"A 22-year-old man has slowly progressive bilateral scapular winging and difficulty raising both arms. On closer look he has mild facial weakness and cannot fully close his eyes. His father had similar shoulder problems."
MCQ Practice Points
Nerve Roots
Q: What are the root values of the long thoracic nerve? A: C5, C6 and C7 (the nerve of Bell).
Direction
Q: Medial winging worse on a wall push-up indicates weakness of which muscle? A: Serratus anterior (long thoracic nerve palsy).
Iatrogenic
Q: Lateral winging with a drooping shoulder after posterior triangle neck surgery suggests injury to which nerve? A: The spinal accessory nerve (cranial nerve XI), causing trapezius palsy.
Salvage - Serratus
Q: What is the salvage tendon transfer for fixed serratus anterior palsy? A: Transfer of the sternal head of pectoralis major to the inferior angle of the scapula (often with a fascial/tendon graft).
Salvage - Trapezius
Q: Which muscles are transferred in the Eden-Lange procedure? A: Levator scapulae, rhomboid minor and rhomboid major, moved laterally to recreate the trapezius vectors.
Neuralgic Amyotrophy
Q: What imaging finding is now considered a hallmark of neuralgic amyotrophy? A: Hourglass-like nerve constrictions on high-resolution MRI or ultrasound.
Guidelines, Registries and Global Practice
Global Epidemiology
- Serratus anterior palsy (long thoracic nerve) is the most common cause of true scapular winging, typically affecting active young adults through traction, sport or neuritis.
- Trapezius palsy (spinal accessory nerve) is most often iatrogenic, following posterior triangle neck surgery or lymph node biopsy.
- Neuralgic amyotrophy is now recognised as more common than historically assumed, often post-viral or post-vaccination, and frequently underlies "idiopathic" winging.
Side-by-Side Practice Comparison
| Issue | Serratus (Long Thoracic) | Trapezius (Spinal Accessory) | FSHD (Myopathy) |
|---|---|---|---|
| Winging direction | Medial | Lateral | Bilateral / mixed |
| First-line | Conservative ~12 to 24 months | Early nerve repair if recent injury | Genetic dx, supportive |
| Nerve surgery | Neurolysis if refractory | Repair/graft within ~12 months | Not applicable |
| Salvage | Pectoralis major transfer | Eden-Lange transfer | Scapulothoracic arthrodesis |
Practice Variation: High vs Limited Resource Settings
- High-resource: Routine EMG, high-resolution ultrasound and MRI for nerve constrictions, microsurgical nerve repair and the full range of tendon transfers and fusion.
- Limited-resource: Diagnosis is often clinical (direction of winging plus provocation tests); conservative rehabilitation is the mainstay, and tendon transfers or fusion deliver high value where microsurgical nerve reconstruction is unavailable.
- Across all settings: Skilled physiotherapy for scapular stabilisation and a watchful period for spontaneous recovery are emphasised before any salvage surgery.
Clinical summary
Pattern Recognition
- •Medial winging, worse on push-up = serratus / long thoracic (C5-7)
- •Lateral winging, drooping shoulder = trapezius / spinal accessory (XI)
- •Subtle medial winging, angle rotated out = rhomboids / dorsal scapular
- •Bilateral + facial weakness = FSHD
Causes (TRAP)
- •Trauma / Traction
- •Rucksack / Repetitive sport
- •Amyotrophy (neuralgic / Parsonage-Turner)
- •Postsurgical (neck biopsy - accessory nerve)
Investigations
- •EMG / NCS - confirm, localise, grade, follow reinnervation
- •MRI / ultrasound - muscle atrophy and nerve constrictions
- •CT - exclude bony / snapping scapula
Treatment Ladder
- •Conservative physio for ~12 to 24 months (neurogenic)
- •Nerve surgery (neurolysis / repair) ideally within 12 months
- •Serratus salvage: pectoralis major transfer
- •Trapezius salvage: Eden-Lange; FSHD: scapulothoracic fusion