High-yield overview
A Painless Right-Sided Mid-Clavicular Lump
PainlessMobile mid-clavicular lump from birth
RIGHT-sidedAlmost always (left = situs inversus)
NOT NFUnlike congenital tibial pseudarthrosis
Observe / operateSurgery for symptoms/cosmesis
Key features & differentials
Congenital pseudarthrosis of clavicle (CPC)
PatternPainless failure of fusion of the medial and lateral clavicular ossification centres -> a mobile, non-tender mid-clavicular lump with rounded sclerotic bone ends (no callus); almost always RIGHT-sided.
Treatment
Clavicle BIRTH fracture (differential)
PatternFollows birth trauma, is initially PAINFUL, and HEALS with abundant CALLUS and immobilisation - the key distinction from CPC, which does not heal.
Treatment
Cleidocranial dysplasia (differential)
PatternBILATERAL clavicular defects/absence plus skull (delayed fontanelle/Wormian bones), dental and other skeletal features (RUNX2 mutation).
Treatment
Critical Must-Knows
- Congenital pseudarthrosis of the clavicle (CPC) is a RARE disorder in which the medial and lateral ossification centres of the clavicle FAIL TO FUSE, producing a PAINLESS, mobile, non-tender LUMP over the MIDDLE THIRD of the clavicle, usually noticed in infancy/early childhood, with rounded SCLEROTIC non-united bone ends and NO callus on radiographs.
- It is almost ALWAYS RIGHT-SIDED; the rare LEFT-sided cases are associated with DEXTROCARDIA/situs inversus, and bilateral cases are uncommon - the right predominance is attributed to the higher position of the subclavian artery on the right (pulsation theory).
- Crucially, CPC is NOT associated with NEUROFIBROMATOSIS - this contrasts with congenital pseudarthrosis of the TIBIA, which IS strongly associated with NF1 and is far harder to treat; this distinction is a classic exam point.
- The main DIFFERENTIAL is a CLAVICLE BIRTH FRACTURE: a birth fracture follows trauma, is initially PAINFUL and HEALS with abundant CALLUS and simple immobilisation, whereas CPC is painless, present without trauma and does NOT heal spontaneously; the other differential is CLEIDOCRANIAL DYSPLASIA (BILATERAL clavicular defects with cranial/dental features, RUNX2 mutation).
- CPC is usually PAINLESS and NON-PROGRESSIVE with little or no functional deficit, so MANY cases can be simply OBSERVED; the indications for SURGERY are symptoms (pain, fatigue), cosmetic concern about the prominent lump, or functional problems, typically operated from around age 3-6 years.
- SURGICAL treatment is RESECTION of the pseudarthrosis with autologous (ILIAC CREST) bone grafting and internal FIXATION (plate, or elastic stable intramedullary nail/K-wire), which gives high union rates and good functional/cosmetic outcomes; AUTOGRAFT is preferred to allograft (allograft has higher non-union).
Clinical Pearls
- “CPC = painless, mobile MID-clavicular lump from failed fusion of ossification centres; rounded sclerotic ends, no callus; almost always RIGHT-sided.
- “NOT associated with neurofibromatosis (vs congenital pseudarthrosis of the TIBIA, which IS). Left-sided CPC -> think situs inversus/dextrocardia.
- “Differentiate from birth fracture (painful, heals with callus) and cleidocranial dysplasia (bilateral + cranial/dental). Observe if asymptomatic; resection + iliac-crest autograft + fixation if symptomatic/cosmetic.
Two Classic Distinctions
CPC vs birth fracture
CPC is painless, present without trauma and does NOT heal; a clavicle birth fracture is initially painful, follows trauma and heals with callus on immobilisation.
CPC vs tibial pseudarthrosis
CPC is NOT associated with neurofibromatosis and treats well; congenital tibial pseudarthrosis IS strongly NF1-associated and is notoriously difficult.
Presentation & Radiology
A Painless Lump in the Right Mid-Clavicle
CPC results from failure of fusion of the medial and lateral clavicular ossification centres, presenting in infancy or early childhood as a painless, mobile, non-tender LUMP over the middle third of the clavicle. It is almost always RIGHT-sided; left-sided cases should prompt consideration of dextrocardia/situs inversus, and bilateral cases are rare. On radiographs the bone ends are rounded and sclerotic and non-united with NO callus - distinguishing it from a healing fracture. The condition is non-progressive with little functional deficit, and importantly it is NOT associated with neurofibromatosis (in contrast to congenital pseudarthrosis of the tibia).
Differential Diagnosis & Management
Confirm It Is Not a Fracture or Cleidocranial Dysplasia
- Clavicle birth fracture: the main differential - it follows birth trauma, is initially painful, and HEALS with abundant callus and simple immobilisation; CPC is painless, atraumatic and does not heal.
- Cleidocranial dysplasia: suspect if the clavicular defects are BILATERAL or there are cranial features (delayed closure of fontanelles, Wormian bones), dental anomalies and other skeletal signs (a RUNX2 disorder).
- Neurofibromatosis: CPC is NOT associated with NF - but congenital pseudarthrosis of the tibia IS, so reserve NF concern for tibial (not clavicular) pseudarthrosis. Diagnosis is clinical (painless mid-clavicular mass) plus a radiograph showing the characteristic non-united rounded sclerotic ends.
Observe or Operate
- Observation: because CPC is usually painless, non-progressive and causes little functional deficit, many children need only reassurance and observation.
- Surgery (indications): symptoms (pain, shoulder fatigue), troublesome cosmetic prominence, or functional limitation - typically performed from around age 3-6 years.
- Technique: RESECTION of the pseudarthrosis with autologous ILIAC CREST bone grafting and internal FIXATION (a plate, or an elastic stable intramedullary nail / K-wire) - giving high union rates and good functional and cosmetic outcomes.
- Graft choice: AUTOGRAFT is preferred; allograft has a higher non-union rate. Intramedullary devices may achieve faster union and easier removal than plates.
Evidence & Key Studies
Evidence
Comparison of fixation methods in the treatment of congenital pseudarthrosis of the clavicle (multicentre)
Li J, Tang SP, Mei HB, et al. • Journal of Orthopaedic Surgery and Research (2021)
Key Findings:
- In 15 clavicles (11 children), pseudarthrosis resection with iliac crest bone autograft and fixation (plate vs elastic stable intramedullary nail/K-wires) achieved radiological healing in almost all.
- Elastic stable intramedullary nailing or K-wires achieved a shorter union time and easier implant removal than plates, with no difference in complications or clinical outcome.
- Surgical resection with iliac crest autograft is an effective treatment, and surgery is recommended for symptomatic congenital pseudarthrosis of the clavicle.
Evidence
Congenital pseudarthrosis of the clavicle: a report on 27 cases
Di Gennaro GL, Cravino M, Martinelli A, et al. • Journal of Shoulder and Elbow Surgery (2016)
Key Findings:
- In 27 cases, operated patients (mostly for cosmetic appearance) were treated by pseudarthrosis resection and K-wire fixation, usually with iliac crest autograft.
- Bone healing was achieved in 74%, all operated patients were pain-free with full range of motion, and no neurovascular complications occurred.
- Use of allograft was associated with a high non-union rate, so autologous iliac crest grafting gave better functional and cosmetic outcomes.
Evidence Attribution
According to PubMed, the effectiveness of resection plus iliac crest autograft and the comparison of fixation methods (intramedullary devices giving faster union) come from the cited Li multicentre study, and the good functional/cosmetic outcomes with autograft (and high non-union with allograft) from the cited Di Gennaro series. The painless right-sided presentation, the rounded non-united radiographic appearance, the non-association with neurofibromatosis and the distinction from a birth fracture and cleidocranial dysplasia are standard, well-established paediatric teaching. (See also our Clavicle Fractures, Cleidocranial Dysplasia and Congenital Tibial Pseudarthrosis topics.)
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
Viva scenarioStandard
Clinical prompt
“An infant has a painless, mobile lump over the middle of the right clavicle. What is the likely diagnosis, what are the key differentials, and how would you manage it?”
Practical approach
A painless, mobile, non-tender lump over the middle third of the right clavicle in an infant is most likely congenital pseudarthrosis of the clavicle, which results from failure of fusion of the medial and lateral ossification centres of the clavicle, leaving non-united, rounded, sclerotic bone ends with no callus on the radiograph. It is almost always right-sided, and a left-sided lesion should make me consider dextrocardia or situs inversus, while bilateral lesions are rare. The key differentials are a clavicle birth fracture and cleidocranial dysplasia. A birth fracture is distinguished because it follows birth trauma, is initially painful, and heals with abundant callus and simple immobilisation, whereas congenital pseudarthrosis is painless, atraumatic and does not heal. Cleidocranial dysplasia is suggested by bilateral clavicular defects together with cranial features such as delayed fontanelle closure and Wormian bones, dental anomalies, and other skeletal signs, and is a RUNX2 disorder. An important exam point is that congenital pseudarthrosis of the clavicle is not associated with neurofibromatosis, in contrast to congenital pseudarthrosis of the tibia, which is. Management depends on symptoms: because the condition is usually painless, non-progressive and causes little functional deficit, many children need only reassurance and observation. Surgery is indicated for symptoms such as pain or fatigue, troublesome cosmetic prominence, or functional limitation, typically from around three to six years of age, and consists of resection of the pseudarthrosis with autologous iliac crest bone grafting and internal fixation with a plate or an intramedullary device, which gives high union rates and good outcomes; autograft is preferred to allograft, which has a higher non-union rate.
Key clinical points
Painless mobile MID-clavicle lump (right) + non-united rounded sclerotic ends, no callus = CPC
Differentials: birth fracture (painful, heals with callus) and cleidocranial dysplasia (bilateral + cranial/dental)
NOT associated with neurofibromatosis (vs congenital tibial pseudarthrosis); left-sided -> situs inversus
Observe if asymptomatic; surgery (resection + iliac-crest autograft + fixation) for symptoms/cosmesis (autograft > allograft)
Common pitfalls
Mistaking it for a birth fracture (which heals) or vice versa
Attributing it to neurofibromatosis (that's the tibia)
Using allograft (higher non-union) instead of autograft
Further questions
“Which side is CPC almost always on? - The right (left -> consider situs inversus)”
“Which pseudarthrosis IS associated with NF1? - Congenital pseudarthrosis of the TIBIA (not clavicle)”
Viva scenarioStandard
Clinical prompt
“How does congenital pseudarthrosis of the clavicle differ from that of the tibia, and what does this mean for treatment and prognosis?”
Practical approach
Although they share the name, congenital pseudarthrosis of the clavicle and of the tibia are very different conditions. Congenital pseudarthrosis of the clavicle is a benign, usually painless failure of fusion of the clavicular ossification centres, almost always on the right, with no association with neurofibromatosis; it is non-progressive, causes little functional deficit, and when treatment is needed it responds well to resection of the pseudarthrosis with iliac crest autograft and internal fixation, achieving high union rates and good cosmetic and functional outcomes, so the prognosis is excellent and many cases simply need observation. Congenital pseudarthrosis of the tibia, by contrast, is strongly associated with neurofibromatosis type 1, typically presents with anterolateral bowing of the tibia that progresses to fracture and a recalcitrant pseudarthrosis, and is notoriously difficult to treat, often requiring complex surgery such as intramedullary rodding, bone grafting and sometimes vascularised fibular transfer or bone transport, with a high risk of refracture and non-union and a guarded prognosis. So the clinical lesson is that the clavicular form is benign and treatment is straightforward, whereas the tibial form is a serious, NF1-associated condition with a difficult course, and the two must not be conflated.
Key clinical points
Clavicle CPC: benign, painless, right-sided, NOT NF-associated; treats well (resection + autograft + fixation); excellent prognosis
Tibial congenital pseudarthrosis: strongly NF1-associated; anterolateral bowing -> fracture/recalcitrant nonunion; difficult
Tibial treatment complex (IM rod + graft +/- vascularised fibula/bone transport); high refracture/nonunion
Do not conflate the two despite the shared name
Common pitfalls
Assuming the clavicular form is as difficult as the tibial form
Forgetting the NF1 association is with the TIBIA
Underestimating tibial pseudarthrosis prognosis
Further questions
“Which is NF1-associated and difficult? - Congenital pseudarthrosis of the tibia”
“Prognosis of clavicular CPC? - Excellent (benign; observe or straightforward surgery)”
Mnemonics & Memory Aids
Mnemonic
CLAVICLE
C
Congenital failure of ossification-centre fusion
L
Lump - painless, mobile, mid-clavicle
A
Almost always RIGHT-sided (left -> situs inversus)
V
Vascular (subclavian) pulsation theory for right predominance
I
Is NOT neurofibromatosis (unlike the tibia)
C
Callus absent - rounded sclerotic ends (not a fracture)
LE
Leave alone (observe) or excise + graft (autograft) if symptomatic
Hook:CPC of the CLAVICLE: painless right-sided lump, not NF, observe or graft.
Mnemonic
NOT NF
N
NOT a fracture (no trauma, no callus, painless)
O
On the right (almost always)
T
Tibia is the NF1 one - not the clavicle
NF
No NeuroFibromatosis association for the clavicle
Hook:Clavicular pseudarthrosis = NOT NF (that's the tibia).
Exam day cheat sheet
Congenital Pseudarthrosis of the Clavicle - Exam Day Cheat Sheet
What it is
- Failure of fusion of the clavicular ossification centres
- Painless, mobile, non-tender mid-clavicular lump from infancy
- Almost always RIGHT-sided (left -> dextrocardia/situs inversus)
Radiology & associations
- Rounded, sclerotic non-united bone ends; NO callus
- NOT associated with neurofibromatosis (vs congenital tibial pseudarthrosis)
- Non-progressive; little functional deficit
Differentials
- Clavicle birth fracture (painful, trauma, heals with callus)
- Cleidocranial dysplasia (bilateral + cranial/dental, RUNX2)
- Diagnosis: clinical + radiograph
Management
- Observe if asymptomatic (usually painless, good function)
- Surgery for symptoms/cosmesis (~age 3-6): resection + iliac-crest autograft + fixation
- Autograft > allograft (lower non-union); IM device gives faster union than plate