Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders

Purpose: Cleidocranial dysplasia is an autosomal dominant disorder characterized by defective ossification of the intramembraneous ossification (primarily the clavicles, cranium, and pelvis), and it is caused by mutations in the RUNX2 gene that is responsible for osteoblast differentiation. Spine deformities were of progressive nature and considered to be the major orthopedic abnormalities encountered in our practice in patients with cleidocranial dysplasia. We aimed to further delineate the underlying spine pathology and its etiological understanding. Extraspinal deformities were dealt with respectively.

Material and methods: In this paper, we describe 7 patients who were consistent with the phenotypic and the genotypic characterization of cleidocranial dysplasia. Reformatted computed tomography (CT) scans have been applied in several instances to further understand the underlying pathology of progressive spine tilting. Radiographs were sufficient to illustrate other skeletal malformations.

Results: Anatomical survey demonstrates that a broad spectrum of frequently unrecognized orthopedic aberrations were encountered. We believe that torticollis has evolved in connection with the persistence of synchondrosis of the skull base and the upper cervical spine and these are strongly correlated to the well-known pathology of posterior occipital synchondrosis. Similarly, scoliosis and kyphoscoliosis resulted from the pathologic aberration of the cartilaginous stage of disrupted embryological development. All our results are discussed for the first time. Coxa vara, patellar dysplasia, and genu valgum were observed as extraspinal deformities.

Conclusion: This paper includes for the first time the anatomical analysis of the malformation complex of the craniocervical and the entire spine in patients with cleidocranial dysplasia. Reformatted CT scan was the modality of choice. We were able to illustrate that the persistence of skull base and the cervical spine synchondrosis were correlated with the pathological mechanism of the posterior occipital synchondrosis. Therefore, injuries to the craniocervical region in these patients might lead to a wide range of dreadful complications, ranging from complete atlanto-occipital or atlanto-axial dislocation to nondisplaced occipital condyle avulsion fractures with the possibility of morbid and or mortal outcome. On the other hand, the persistence of a cartilaginous spine was the reason behind the progressive spine tilting. This pathological form can be considered as a notoriously unpredictable malformation complex. The value of presenting these patients is to demonstrate that the genotype is not a precise index to assess the severity and the natural history of the phenotype.