|Year : 2017 | Volume
| Issue : 2 | Page : 113-115
Supernumerary clavicles with multiple skeletal malformations in an unusual association
Ibrahim Aliyu1, Zainab F Ibrahim2, Godpower Chinedu Michael3
1 Department of Paediatrics, Aminu Kano Teaching Hospital, Kano, Nigeria
2 Department of Nursing, Aminu Kano Teaching Hospital, Kano, Nigeria
3 Department of Genereal Outpatient, Aminu Kano Teaching Hospital, Kano, Nigeria
|Date of Web Publication||15-Sep-2017|
Department of Paediatrics, Aminu Kano Teaching Hospital, Kano
Source of Support: None, Conflict of Interest: None
The clavicle is one of the earliest bones to ossify in utero. Their associated malformations are uncommon. The most common among them is pseudoarthrosis of the clavicle. However, the supernumerary clavicle is a rarity. It is often isolated, unilateral, and an accidental finding seen at adult age because it is asymptomatic; however, the case of a 3-month-old girl which was diagnosed much earlier because she had other associated malformations is reported.
Keywords: Bilateral supernumerary clavicles, childhood, multiple skeletal malformations, Poland syndrome
|How to cite this article:|
Aliyu I, Ibrahim ZF, Michael GC. Supernumerary clavicles with multiple skeletal malformations in an unusual association. Saudi J Health Sci 2017;6:113-5
| Introduction|| |
The clavicle lies horizontally between the scapula and the sternum and serves as a strut. It has two smooth curves: convex medially from the sternum and concave laterally toward the coracoid process of the scapula, giving it an “S” shaped morphology. Congenital anomaly of the clavicle is quite uncommon; clavicular fracture being the most common acquired abnormality witnessed in newborn., However, pseudoarthrosis of the clavicle is the most reported among the congenital anomalies of the clavicle with about <200 documented cases so far in the in the literature. A double clavicle (”os subclaviculare”) is a rarity.,, Few cases have been reported so far and its exact mechanism of occurrence is not completely understood. While the fragmentation hypothesis appears plausible, it does not explain all cases especially in the index case in which it was associated with multiple skeletal anomalies.
Polydactyly of the foot may occur as an isolated anomaly but may also be associated with other congenital malformation syndrome such as Ellis-van Creveld syndrome;, it may be sporadic but autosomal mode of inheritance with variable penetrance has been described, and pre- and post-axial polydactyly forms have been described.
Although anomalies the chest wall, such as absent/hypoplastic pectorialis major, absent ribs, absent/hypoplastic nipple, and syndactyly of the upper extremity has been established in patients with Poland syndrome, the association of double clavicles, chest wall deformity with hypoplastic ribs, trigonocephaly, postaxial polydactyly, and congenital heart disease to the best of our knowledge has not been reported before now.
| Case Report|| |
A 3-month-old girl presented with difficulty with breathing noticed shortly after delivery; this was associated with central cyanosis; parents noticed poor weight gain since birth despite good appetite. She was delivered at term, and the pregnancy and delivery were not adversely eventful. She was the first child in a nonconsanguineous union. The physical examination revealed a small for age child (2.8 kg), length of 58 cm, and occipitofrontal circumference of 37 cm. Oxygen saturation using pulse oximeter was between 60% and 70% in room air; she was tachypneic and tachycardic, with displaced apex beat at the 5th left intercostal space lateral to the midclavicular line, there was pansystolic murmur at the left sternal margin. She was dysmorphic with triangular-shaped skull (trigonocephalic) both the anterior and posterior fontanels were patent, she had a short neck, widened nipple space, depressed sternum (pectus excavatum), and sinus on the right upper limb [Figure 1], the right foot had a postaxial polydactyly [Figure 2], talipes equinovarus deformity. The full blood count showed a packed cell volume of 45.8% while other parameters were not remarkable; chest X-ray showed absent 5th–8th right ribs, double right/left clavicles, and cardiomegaly with increased pulmonary vascularity [Figure 3], on further review of the chest, we noticed that there were two clavicular shadows each on both side; therefore, an impression of bilateral supernumerary clavicles was made (”os subclaviculare”). The electrocardiogram showed left ventricular hypertrophy, while echocardiography revealed tricuspid atresia with atrial and ventricular septal defects. She was managed for cyanotic congenital heart disease (tricuspid atresia) with multiple skeletal malformations.
|Figure 1: Anterior chest wall deformity showing widely spaced nipples, pectus carinatum, and sinus on the right upper limb|
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|Figure 3: Chest X-ray showing double clavicle, absent 5th–8th right ribs and cardiomegaly|
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| Discussion|| |
The clavicle is the first bone to ossify in utero at about the 6th–7th week of life; but its epiphysis is the last to appear at about the 18th year of life. Theories has been put forward to explain the mechanism of clavicular duplication; first, it is proposed that possibly one of the two ossifying centers is displaced in utero resulting in double clavicles, second, it maybe that there are more than two ossifying centers in utero resulting in multiple clavicle formation; these should result in short segments of clavicle since each ossification center is responsible for each half of the clavicle (medial and lateral segments). Third, some authors believe that early in clavicular development, fragment of the tissue separates from the main ossification centers resulting in the formation of the whole length of an accessory clavicle which is often smaller than the main clavicle. “Os subclaviculare” is asymptomatic and usually an accidental finding, which is similar to our experience. However, unlike our index case, most were diagnosed at adulthood ,, but our case was in childhood because of the associated difficulty in breathing which warranted a chest X-ray at an earlier age. Furthermore, most reported cases were unilateral, but our patient had bilateral involvement.,,
Most of the clinical features observed in the index case, such as the chest wall deformity, hypoplastic ribs, and its occurrence on the right hemithorax are similar to those in patients with Poland syndrome; however, the absence of upper limb anomalies such as brachydactyly is noted in this index case which is similar to the previous report in an 8-year-old Nigerian; therefore the index case maybe a variant of Poland syndrome, because Poland syndrome has been associated with anomalies of other organs such as encephalocele, hypoplasia of the kidney, abnormality of the gastrointestinal tract, diaphragmatic hernia, and dextrocardia/dextroposition.
| Conclusion|| |
Congenital musculoskeletal malformations may be more extensive than often appreciated because some may be asymptomatic; therefore, X-rays should be extensively reviewed so that lesions such as a double clavicle are not missed.
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Conflicts of interest
There are no conflicts of interest.
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