Ankylosing spondylitis (AS) is a progressive multisystem chronic inflammatory disorder. The hallmark of this pathological process is a progressive fusion of the zygapophyseal joints and disc spaces of the axial skeleton, leading to a rigid kyphotic deformity and positive sagittal balance. The ankylosed spine is unable to accommodate normal mechanical forces, rendering it brittle and susceptible to injury. Traumatic hyperextension injury of the cervical spine leading to atlantoaxial subluxation (AAS) in AS patients can often be fatal. We report a non-traumatic mechanism of injury in AS progressing to AAS attributable to persistent hyperextension, which resulted in fatal migration of C2 through the foramen magnum.

Cite this article: Bone Joint J 2013;95-B:206–9.

In order to determine the epidemiology of adult scoliosis in the elderly and to analyse the radiological parameters and symptoms related to adult scoliosis, we carried out a prospective cross-sectional radiological study on 1347 adult volunteers. There were 615 men and 732 women with a mean age of 73.3 years (60 to 94), and a mean Cobb angle of 7.55° (sd 5.95).

In our study, 478 subjects met the definition of scoliosis (Cobb angle ≥10°) showing a prevalence of 35.5%. There was a significant difference in the epidemiological distribution and prevalence between the age and gender groups. The older adults showed a larger prevalence and more severe scoliosis, more prominent in women (p = 0.004). Women were more affected by adult scoliosis and showed more linear correlation with age (p < 0.001). Symptoms were more severe in those with scoliosis than in the normal group, but were similar between the mild, moderate and severe scoliosis groups (p = 0.224) and between men and women (p = 0.231).

Adult scoliosis showed a significant relationship with lateral listhesis, vertebral rotation, lumbar hypolordosis, sagittal imbalance and a high level of the L4–5 disc (p < 0.0001, p < 0.0001, p = 0.002, p = 0.002, p < 0.0001 respectively). Lateral listhesis, lumbar hypolordosis and sagittal imbalance were related to symptoms (p < 0.0001, p = 0.001, p < 0.0001 respectively).

Extensive limb lengthening may be indicated in achondroplastic patients who wish to achieve a height within the normal range for their population. However, increasing the magnitude of lengthening is associated with further complications particularly adjacent joint stiffness and fractures. We studied the relationship between the magnitude of femoral lengthening and callus pattern, adjacent joint stiffness and fracture of the regenerate bone in 40 femoral lengthenings in 20 achondroplastic patients. They were divided into two groups; group A had lengthening of less than 50% and group B of more than 50% of their initial femoral length. The patterns of radiological callus formation were classified according to shape, type and features. The incidence of callus features, knee stiffness and regenerate bone fracture were analysed in the two groups. Group B was associated with an increased incidence of concave, lateral and central callus shapes, adjacent joint and stiffness and fracture. Statistically, the incidence of stiffness in adjacent joints and regenerate bone fracture was significantly associated with the magnitude of lengthening.

We suggest that careful radiological assessment of the patterns of callus formation is a useful method for the evaluation and monitoring of regenerate bone.