title: Static versus dynamic factors for the development of myelopathy in patients with cervical ossification of the posterior longitudinal ligament.
abstract: We studied 27 patients with cervical ossification of the posterior longitudinal ligament (OPLL) but no clinical symptoms of myelopathy. We investigated the occupation ratio of the spinal canal by OPLL with cervical radiographs, assessed the morphological types of OPLL, and measured the segmental range of motion (ROM) at the level of maximum cord compression on flexion and extension radiographs. Patients were classified as having continuous-type OPLL (17 patients), mixed-type OPLL (seven patients), or segmental-type OPLL (three patients). The segmental ROM was negatively correlated with the OPLL occupation ratio (r=-0.49, p<0.01). No patient developed myelopathy during the study period. Three patients with massive OPLL did not develop myelopathy and the mobility of their cervical spine was highly restricted, suggesting that dynamic factors such as the segmental ROM preferentially contribute to the development of myelopathy in patients with cervical OPLL. Thus, by controlling the dynamic factors (hypermobility), we might be able to reduce neurological deterioration in patients with cervical OPLL.
authors.affiliation: Spine Section, Department of Orthopaedic Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo-ku, Chiba 260-8677, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Fujiyoshi
authors.forename: Masashi
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Akihiko
authors.initials: A
authors.lastname: Okawa
authors.forename: Junko
authors.initials: J
authors.lastname: Kawabe
authors.forename: Koichi
authors.initials: K
authors.lastname: Hayashi
authors.forename: Tomonori
authors.initials: T
authors.lastname: Endo
authors.forename: Takeo
authors.initials: T
authors.lastname: Furuya
authors.forename: Masao
authors.initials: M
authors.lastname: Koda
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000328:Adult; D000368:Aged; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology; D018450:Disease Progression; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000150:complications* / Q000000981:diagnostic imaging; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013117:Spinal Cord Compression / Q000000981:diagnostic imaging / Q000209:etiology; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000209:etiology*; D001745:Urinary Bladder Diseases / Q000209:etiology