✓The authors report a new technique for C-1 laminoplasty without fusion in the treatment of cervical myelopathy associated with a retroodontoid pseudotumor (also known as a phantom tumor). The authors review the cases of three patients who underwent C-1 laminoplasty in which hydroxyapatite was used and fusion was not performed. All patients suffered from severe progressive myelopathy before surgery. Magnetic resonance imaging revealed a retroodontoid pseudotumor compressing the spinal cord at the C-1 level in all cases. Computed tomography was performed to examine the extent of bone erosion at the atlantoaxial joint and dens. Clinical parameters included neurological function, measured using the Japanese Orthopaedic Association score, and neck pain. Imaging parameters included pre- and postoperative atlas–dens intervals; the space available for the spinal cord; instability of the atlantoaxial joints; osteoarthritic changes of the atlantoaxial joint; postoperative changes in T2 high-intensity signal; and postoperative alteration in the size of the pseudotumor. Magnetic resonance imaging demonstrated complete disappearance of the pseudotumor in two cases and partial reduction in one case. In all three cases sufficient neurological recovery was observed. The mean recovery rate was 87.0%. This new technique is less invasive than standard procedures, preserves the cervical range of motion, and avoids the morbidity of obtaining a bone graft and placing instrumentation. The authors conclude that C-1 laminoplasty without fusion is an option in the surgical management of cervical myelopathy associated with a retroodontoid pseudotumor, either without C1–2 instability or with slight, but reducible, C1–2 instability.

Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by ectopic bone formation in the spinal ligaments, and mechanical stress has been suggested to play an important role in the progression of OPLL. To identify the genes that participate in OPLL, the differential display reverse transcription-polymerase chain reaction (RT-PCR) method was used. A 283-base pair cDNA fragment corresponding to prostaglandin I 2 (PGI 2 ) synthase was highly expressed in OPLL cells compared with non-OPLL cells. To examine the effect of mechanical stress on the expression of PGI 2 synthase, cells were subjected to uniaxial cyclic stretch (0.5 Hz, 20% stretch), and PGI 2 synthase mRNA expression was assessed by quantitative RT-PCR. Cyclic stretch induced an increase in PGI 2 synthase in OPLL cells in a time-dependent manner, whereas no change was observed in non-OPLL cells. Cyclic stretch for 9 h also induced a 2.86ϫ increase in PGI 2 production. Beraprost (a stable PGI 2 analog) and dibutyryl cAMP (a membrane-permeable cAMP analog) increased the mRNA expression of alkaline phosphatase (ALP) as a marker for osteogenic differentiation up to 240 and 200%, respectively, in OPLL cells, whereas no change was observed in non-OPLL cells. The increases in ALP mRNA induced by beraprost and cyclic stretch were both inhibited by SQ22536, a potent adenylate cyclase inhibitor. These data suggest that the increase in PGI 2 synthase induced by mechanical stress plays a key role in the progression of OPLL, at least in part through the induction of osteogenic differentiation in spinal ligament cells via the PGI 2 /cAMP system.

Augmented PGE2 production by mineralizing osteoblasts after IL-1beta treatment, and the involvement of IL-1beta-induced cPLA2, sPLA2, COX-2 and PGE synthase activities in this phenomenon were demonstrated.

IntroductionMutations in the gene encoding the type II collagen gene (COL2A1) have been found to affect the entire skeletal system. Recently, inheritable skeletal dysplasia caused by novel COL2A1 mutations has been linked to an inherited disease of the hip joint that neither involves the entire skeletal system nor is characterized by the presence of concomitant disorders, such as spinal or ocular abnormalities.Case presentationA 27-year-old Japanese woman previously diagnosed with avasucular necrosis (AVN) of the femoral head on the basis of radiological findings was referred to the study site for surgical management of a painful hip joint. She had no history of disease but suffered from bilateral hip joint lesions. Analysis of her pedigree revealed that bilateral hip joint lesions affected more than three generations of her family. Based on these findings, haplotype analysis of her and her family members was performed by examining select candidate genes from the critical interval for epiphyseal dysplasia of the femoral head on 12q13 and sequencing the promoter and exonic regions of COL2A1.ConclusionA novel COL2A1 mutation (c.1744G>A) was identified within one Japanese family.

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