Facioscapulohumeral Muscular Dystrophy
- FSHD is one of the most common muscular dystrophies (estimated prevalence around 1 in 15,000) and produces a characteristic DESCENDING, often ASYMMETRIC pattern of weakness - FACE first (difficulty whistling, drinking through a straw, burying the eyelashes on eye closure), then the SHOULDER GIRDLE / periscapular muscles (scapular winging), then the HUMERAL muscles (biceps/triceps wasting with relative forearm sparing, the 'Popeye arm'), with later trunk, abdominal (a positive Beevor's sign) and lower-limb (foot-drop) involvement.
- The genetic basis of the common form (FSHD1, around 95%) is a CONTRACTION of the D4Z4 macrosatellite repeat array on chromosome 4q35 on a 'permissive' (polyadenylation-enabling) haplotype, which relaxes the chromatin and allows aberrant expression of the normally silenced DUX4 gene; DUX4 protein is toxic to skeletal muscle. Inheritance is AUTOSOMAL DOMINANT (with variable penetrance); FSHD2 is a rarer digenic form usually involving SMCHD1.
- The principal ORTHOPAEDIC problem is SCAPULAR WINGING: weakness of the scapular stabilisers (serratus anterior, trapezius, rhomboids) lets the scapula ride up and wing, so glenohumeral abduction/flexion is wasted because the scapula is not stabilised on the chest wall - patients often have surprisingly preserved DELTOID power that cannot be used effectively.
- SCAPULOTHORACIC ARTHRODESIS (STA) is the established surgical treatment for severe symptomatic winging when the DELTOID is preserved: fusing the scapula to the ribs gives the deltoid a stable platform, and regardless of the specific fixation technique (multifilament cables alone, or cables/cerclage combined with plates, ideally with autograft) it reliably improves active shoulder elevation and quality of life.
- STA has recognised COMPLICATIONS: PULMONARY complications (pleural effusion, pneumothorax, atelectasis) are common because of the thoracic dissection but usually resolve spontaneously, and there are fixation-related scapular complications (related to the surgeon's learning curve); meticulous technique, careful positioning of the fusion (around 20-30 degrees of scapular abduction), and good postoperative analgesia reduce these.
- There is no disease-modifying cure yet, so care is SUPPORTIVE and MULTIDISCIPLINARY (neurology, genetics, orthopaedics, physiotherapy, respiratory, ophthalmology for the rare retinal vasculopathy/Coats disease and audiology for sensorineural hearing loss); patient selection - preserved deltoid, realistic goals, acceptable respiratory reserve - is the key determinant of a good surgical outcome.
- “FSHD = DESCENDING facio-scapulo-humeral weakness, often ASYMMETRIC; face -> periscapular (winging) -> biceps (Popeye arm, forearm spared); FSHD1 = 4q35 D4Z4 contraction -> DUX4, autosomal dominant.
- “Winging is from weak scapular stabilisers; DELTOID is often PRESERVED but unusable without a stable scapula.
- “Scapulothoracic arthrodesis (STA) is indicated for severe winging with PRESERVED deltoid; improves elevation; pulmonary complications common but usually self-limiting.
Descending, asymmetric weakness: face -> periscapular (winging) -> biceps (Popeye arm, forearm spared) -> trunk/lower limb (foot-drop). FSHD1 = 4q35 D4Z4 contraction -> DUX4.
Scapulothoracic arthrodesis for severe winging when the deltoid is preserved - it gives the deltoid a stable base and restores active elevation.
Pattern of Weakness & Genetics
FSHD is one of the most common muscular dystrophies (estimated prevalence around 1 in 15,000) and weakens muscles in a descending facioscapulohumeral pattern that is characteristically asymmetric. It begins in the face (difficulty whistling, drinking through a straw, or burying the eyelashes), moves to the shoulder girdle / periscapular muscles (producing scapular winging), then the humeral muscles (biceps and triceps wasting with relative sparing of the forearm - the 'Popeye arm'), and later involves the trunk (a positive Beevor's sign, where the umbilicus moves upward on neck flexion) and the lower limb (foot-drop). The common form, FSHD1 (around 95%), is caused by a contraction of the D4Z4 macrosatellite repeats on chromosome 4q35 on a permissive haplotype, which relaxes the chromatin and allows aberrant expression of the normally silenced DUX4 gene; DUX4 protein is toxic to muscle. Inheritance is autosomal dominant, and a rarer digenic FSHD2 (usually SMCHD1) shares the phenotype.
Scapular Winging & Scapulothoracic Arthrodesis
The principal orthopaedic problem is scapular winging. Weakness of the scapular stabilisers (serratus anterior, trapezius, rhomboids) means the scapula is not anchored to the chest wall, so when the deltoid contracts the scapula simply rotates and wings rather than acting as a stable base for glenohumeral elevation - the result is severely limited active abduction and flexion despite a frequently well-preserved deltoid. Scapulothoracic arthrodesis (STA) addresses exactly this: by fusing the scapula to the ribs it converts the unstable scapula into a fixed platform, allowing the preserved deltoid to elevate the arm. Regardless of the specific fixation (multifilament cables alone, or cables/cerclage wires combined with plates, ideally with autograft), STA reliably improves active elevation and quality of life - so the operation hinges on selecting patients with severe symptomatic winging and a preserved deltoid.
Two points govern scapulothoracic arthrodesis. First, the deltoid must be PRESERVED - STA gives the deltoid a stable platform, so if the deltoid itself is weak the operation will not restore useful elevation, making careful assessment of deltoid power an essential part of patient selection. Second, STA involves thoracic dissection and rib fixation, so PULMONARY complications (pleural effusion, pneumothorax, atelectasis) are common - they usually resolve spontaneously, but the patient's respiratory reserve should be assessed beforehand and good postoperative analgesia and chest physiotherapy provided. Because FSHD is a systemic neuromuscular disorder, surgery should always sit within multidisciplinary care with realistic, shared goals.
Evidence & Key Studies
Management of scapular dysfunction in FSHD: biomechanics of winging, arthrodesis indications, techniques and outcomes
- FSHD typically causes scapular winging due to wasting of the periscapular muscles; scapulothoracic arthrodesis (STA) is the current surgical treatment for severe winging with a preserved deltoid.
- Several fixation techniques exist (multifilament cables alone, or cables/cerclage wires combined with single or multiple plates); the authors prefer cables without plates and strongly recommend autograft. Regardless of technique, shoulder elevation and quality of life improve on outcome scores.
- Pulmonary complications are common but usually resolve spontaneously; scapular fixation complications relate to the surgeon's learning curve. Success strongly depends on patient selection and a multidisciplinary team (neurologists, geneticists, orthopaedic surgeons).
The UK FSHD patient registry: prevalence, genetics and presenting features
- FSHD is estimated to affect about 1 in 15,000 people; in the UK registry most patients (91.7%) had FSHD type 1.
- Facial weakness was the most prevalent symptom at onset (59.2%), followed by shoulder-girdle weakness (53.3%), then distal (22.4%) or proximal lower-limb (14.8%) weakness.
- Most patients (85.6%) were ambulant or ambulant with assistance, and 7.9% reported respiratory insufficiency.
According to PubMed, the orthopaedic facts - scapular winging from periscapular wasting, scapulothoracic arthrodesis as the treatment for severe winging with a preserved deltoid, the fixation techniques and use of autograft, the improvement in elevation/quality of life, and the common (usually self-limiting) pulmonary complications - come from the cited Eren EFORT review; the prevalence (~1/15,000), the predominance of FSHD1, and the onset pattern (face then shoulder-girdle then lower limb) with the respiratory-insufficiency figure from the cited Evangelista registry. The 4q35 D4Z4/DUX4 genetics, the descending asymmetric phenotype (Popeye arm, Beevor's sign, foot-drop) and the supportive multidisciplinary framework are standard, well- established teaching. (See also our Scapular Winging and Long Thoracic Nerve Palsy topics.)
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A young adult presents with scapular winging and difficulty lifting the arms, with facial weakness. What is the likely diagnosis and what is the underlying genetics?”
“When would you offer scapulothoracic arthrodesis in FSHD, and what would you warn the patient about?”
Mnemonics & Memory Aids
FSHD
Hook:FSHD: Face, Scapula (winging), Humeral (Popeye arm), DUX4 - descending, asymmetric, dominant.
STA
Hook:STA: Severe winging, Thoracic fixation (pulmonary risk), Active elevation restored (deltoid preserved).
Pattern
- Descending, asymmetric: face -> periscapular (winging) -> humeral (Popeye arm, forearm spared)
- Later: trunk (Beevor's sign), lower limb (foot-drop)
- Prevalence ~1/15,000; onset commonly facial then shoulder-girdle
Genetics
- FSHD1 (~95%): D4Z4 contraction on 4q35 (permissive haplotype) -> DUX4 de-repression
- DUX4 protein is toxic to muscle; autosomal dominant (variable penetrance)
- FSHD2: rarer, digenic (usually SMCHD1)
Orthopaedic problem
- Scapular winging from weak serratus anterior/trapezius/rhomboids
- Deltoid often preserved but unusable without a stable scapula
- Limited active abduction/flexion
Scapulothoracic arthrodesis
- Indication: severe symptomatic winging with PRESERVED deltoid
- Fuse scapula to ribs (~20-30 deg abduction); cables +/- plates, autograft
- Improves elevation/QoL; pulmonary complications common but usually self-limiting; MDT care