We evaluated the impact of lumbar instrumented circumferential fusion on the development of adjacent level vertebral compression fractures (VCFs). Instrumented posterior lumbar interbody fusion (PLIF) has become a popular procedure for degenerative lumbar spine disease. The immediate rigidity produced by PLIF may cause more stress and lead to greater risk of adjacent VCFs. However, few studies have investigated the relationship between PLIF and the development of subsequent adjacent level VCFs.

Between January 2005 and December 2009, a total of 1936 patients were enrolled. Of these 224 patients had a new VCF and the incidence was statistically analysed with other covariants. In total 150 (11.1%) of 1348 patients developed new VCFs with PLIF, with 108 (72%) cases at adjacent segment. Of 588 patients, 74 (12.5%) developed new subsequent VCFs with conventional posterolateral fusion (PLF), with 37 (50%) patients at an adjacent level. Short-segment fusion, female and age older than 65 years also increased the development of new adjacent VCFs in patients undergoing PLIF. In the osteoporotic patient, more rigid fusion and a higher stress gradient after PLIF will cause a higher adjacent VCF rate.

Cite this article: Bone Joint J 2015;97-B:1411–16.

A four-year-old boy presented with a solitary bone cyst in the odontoid process and body of the axis. Plain radiographs showed a radiolucent lesion with extreme thinning of the cortex and MRI demonstrated a high signal intensity in the interlesional matrix. The cystic component extended into the body of the axis through a defect in the epiphyseal plate.

At operation, the cavity of the cyst was found to contain serosanguineous fluid, and histological examination showed that it was lined by a thin layer of connective tissue. The cyst may have originated from a defect in the epiphyseal plate.