Coexistence of Crowned Dens Sign and Calcification of Ligamentum Flavum in the cervical Spine: coincidence or association?

Abstract

Abstract Background: Calcification of the cervical ligamentum flavum(CLF) and periodontoid calcification are two rare diseases in the orthopaedic clinic. Only few reports have described these coexisting conditions. Objectives: We present our cases of cervical radiculomyelopathy caused by CLF combined with or without periodontoid calcification, and the relationship between the two clinical conditions are briefly discussed on the review of data of the literature. Methods: We retrospectively reviewed 33 patients with CLF. In our case series, the clinical and radiological characteristics of patients are described and analyzed. The calcification surrounding the dens is termed as crowned dens sign(CDSign) in our study. And the relationship between the two conditions of CLF and CDSign are discussed. Results:There were 28 women and 5 men aged between 56 and 86 years. Neurological symptoms and neck pain were presented in most patients. Calcification sites on axial CT images were described in 33 cases with 81 levels, C4-5 and C5-6 were attacked most frequently, and multiple- rather than single-level involvement could be observed in our series. CDSign was identified in 26 cases, and the the prevalence were 79%. Following evaluation, 23 patients received posterior surgery, and 8 patients underwent anterior cervical surgery. Conclusions: The coexistence of CDSign and CLF is an uncommon phenomenon. The association of these two diseases is stronger than a coincidence. It is possible that the coexistence of CLF with CDSign may be a rare form of the cervical manifestation of calcium pyrophosphate dihydrate (CPPD) deposition disease.