Radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligament: a multicenter cohort study.
METHODS
A multicenter cohort study was performed retrospectively.


OBJECTIVE
To identify radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligaments (OPLL).


BACKGROUND
The pathomechanism of myelopathy in the OPLL remains unknown. Some patients with large OPLL have not exhibited myelopathy for a long periods of time. Predicting the course of future neurologic deterioration in asyptomatic patients with OPLL is difficult at their initial visit.


METHODS
A total of 156 OPLL patients from 16 spine institutes with an average of 10.3 years of follow-up were reviewed. Subjects underwent a plain roentgenogram, computed tomography (CT), and magnetic resonance imaging of the cervical spine during the follow-up. The trauma history of the cervical spine, maximum percentage of spinal canal stenosis in a plain roentgenogram and CT, range of motion of the cervical spine, and axial ossified pattern in magnetic resonance imaging or CT were reviewed in relation to the existence of myelopathy.


RESULTS
All 39 patients with greater than 60% spinal canal stenosis on the plain roentgenogram exhibited myelopathy. Of 117 patients with less than 60% spinal canal stenosis, 57 (49%) patients exhibited myelopathy. The range of motion of the cervical spine was significantly larger in patients with myelopathy than in those of without it. The axial ossified pattern could be classified into 2 types: a central type and a lateral deviated type. The incidence of myelopathy in patients with less than 60% spinal canal stenosis was significantly higher in the lateral deviated-type group than in the central-type group. Fifteen patients of 156 subjects developed trauma-induced myelopathy. Of the 15 patients, 13 had mixed-type OPLL and 2 had segmental-type OPLL.


CONCLUSIONS
Static and dynamic factors were related to the development of myelopathy in OPLL.
Matsunaga
Shunji
S
Department of Orthopaedic Surgery, Imakiire General Hospital, Kagoshima, Japan. shunji@m.kufm.kaqgoshima-u.ac.jp
Nakamura
Kozo
K
Seichi
Atsushi
A
Yokoyama
Toru
T
Toh
Satoshi
S
Ichimura
Shoichi
S
Satomi
Kazuhiko
K
Endo
Kenji
K
Yamamoto
Kengo
K
Kato
Yoshiharu
Y
Ito
Tatsuo
T
Tokuhashi
Yasuaki
Y
Uchida
Kenzo
K
Baba
Hisatoshi
H
Kawahara
Norio
N
Tomita
Katsuro
K
Matsuyama
Yukihiro
Y
Ishiguro
Naoki
N
Iwasaki
Motoki
M
Yoshikawa
Hideki
H
Yonenobu
Kazuo
K
Kawakami
Mamoru
M
Yoshida
Munehito
M
Inoue
Shinsuke
S
Tani
Toshikazu
T
Kaneko
Kazuo
K
Taguchi
Toshihiko
T
Imakiire
Takanori
T
Komiya
Setsuro
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007564:Japan; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017887:Ossification of Posterior Longitudinal Ligament / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D013997:Time Factors; D014057:Tomography, X-Ray Computed