This rare anomaly was first described by Fitzwilliams. The cause of this curious defect remains obscure. The pseudarthrosis is fully present at birth.
Failure of normal ossification of the precartilaginous bridge connecting the acromial and sternal ossific centers of the clavicle or failure of amalgamation of the two clavicular parts may be the cause of congenital pseudarthrosis.
Familial incidence is reported in some patients, particularly in bilateral cases. There is no genetic pattern.
The right clavicle has been affected in almost all the reported cases.
The defect is not due to nonunion of a birth fracture of normal bone. All neonatal clavicular fractures unite rapidly with massive callus. Remodeling takes place within a few months, leaving no trace of deformity. Clinically, in a fracture of the clavicle there is a history of trauma, pseudoparalysis of the arm with lack of voluntary limb motion, and pain on passive movement.
Clinical Findings
A nontender swelling just lateral to the middle of the clavicle is discovered at birth or soon afterward. There is no history of birth injury or other trauma.
At the site of pseudarthrosis, the adjacent ends of the clavicular fragments are enlarged, and there is a variable degree of painless mobility between them. The larger sternal fragment is tilted upward and lies in front of and sightly above the medial end of the smaller acromial portion.
In the newborn or young infant, congenital pseudarthrosis of the clavicle should not be misdiagnosed as a fracture of the clavicle. The history of trauma, pseudoparalysis of the arm with lack of voluntary limb motion, pain on passive movemmemnt, and massive callus with the characteristic radiographic appearance of fracture union of the latter entity are lacking in congenital pseudarthrosis of the clavicle.
Because of the weight of the upper limb, the lateral segment of the clavicle is tilted inferiorly, and the shoulder droops, is rotated forward, and is nearer to the midline than the opposite normal side.
The deformity usually increases and becomes unsightly with further growth, more so when there is marked mobility at the site of the pseudarthrosis. The overlying skin becomes thin and atrophic. Cosmetically the deformity may be a source of embarrassment to the child.
There is some drooping of the affected shoulder with asymmetry and prominence of the vertical border of the scapula. Mild pain around the shoulder girdle and upper arm may be present.
There is little or no functional disability. A few children complain of weakness of the arm and limitation of shoulder abduction.
Radiographic Findings
In the radiograph the pseudarthrosis of the clavicle immediately lateral to its middle is evident. In congenital pseudarthrosis the bone ends are enlarged at the pseudarthrosis site.
In congenital pseudarthrosis of the clavicle there are no other skeletal abnormalities present, a feature that distinguishes it from cleidocranial dysostosis.
Treatment
Treatment consists of excision of the pseudarthrosis mass, curettage of the bone ends, internal fixation with a threaded Steinmann pin, and grafting with cancellous onlay autogenous bone graft from the ilium.
Results of surgical repair of pseudarthrosis of the clavicle are very satisfactory. Neurovascular injury can occur as a complication.
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