Multicenter study investigating the postoperative progression of ossification of the posterior longitudinal ligament in the cervical spine: a new computer-assisted measurement

Abstract

<jats:p content-type="fine-print"><jats:italic>Object.</jats:italic> Ossification of the posterior longitudinal ligament (OPLL) often progresses after surgery, and this may cause late-onset neurological deterioration. There have been few studies, however, to clarify any correlation between progression and clinical outcome, partly because of the lack of studies involving reliable and reproducible methods by which detection of progression is made possible. The authors conducted a multicenter study to investigate the occurrence of postoperative progression and to elucidate the possible risk factors in a large-scale patient population, and a novel computer-assisted measurement method was used to provide the basis for future clinical studies.</jats:p> <jats:p content-type="fine-print"><jats:italic>Methods.</jats:italic> The authors analyzed lateral plain radiographs obtained immediately and at 1 and 2 years after surgery in 131 patients who underwent posterior decompression at 13 institutions. The x-ray films were transformed via scanner into digital images; the length and thickness of ossifications were measured using a new computer-assisted measurement system, and the incidence of progression was determined. Odds ratios for progression according to age group and types of OPLL were determined and compared to elucidate significant risk factors of progression.</jats:p> <jats:p content-type="fine-print"><jats:italic>Conclusions.</jats:italic> This is the first multicenter study to investigate the incidence of OPLL progression after posterior decompression by using a standardized measurement method. The rate of postoperative progression at 2 years was 56.5%, which was comparable with results reported in other studies. Progression occurred more frequently in younger-age rather than in older-age patient populations at both 1 and 2 years postoperatively. Mixed-type and continuous-type OPLL progressed more frequently than the segmental-type lesion at 2 years. The results of the present study could serve as basis for future studies to assess the efficacy of drug therapy to prevent OPLL progression.</jats:p>

Ossification of the posterior longitudinal ligament: a review

“…They found that progression was marked in younger patients with continuous-or mixed-type OPLL, consistent with the results of Chiba et al 12 According to progression on the longitudinal axis, the patients with continuous-or mixed-type OPLL were classified according to age. The patients 40-49 years of age showed peak progression at greater than 1 year, whereas the patients older than 50 showed peak progression during the first year of follow-up.…”

“…The rate of OPLL progression was 56.5% at 2 years and was more common in younger patients with continuous-and mixed-type OPLL. 12 Murakami et al 89 reported a case of cervical OPLL in a 67-year-old man with more than 26 years follow-up. They found that the rate of OPLL progression varied during this period.…”

Three-dimensional evaluation of volume change in ossification of the posterior longitudinal ligament of the cervical spine using computed tomography

“…The next step is to analyze the risk factors for OPLL progression using our novel method, to verify those that have been described in previous studies [6,17].…”

“…Chiba et al [6,7] reported the incidence of ossification progression based on computer analysis of X-ray images in patients who had undergone laminoplasty. Measurements of ossification length and thickness using 2D X-ray images are possible to a certain extent [17,18].…”

“…Evaluating the size and growth of OPLL is important to determine the timing of the operation and the risk factors for rapid progression of OPLL. Previous attempts have already been made to measure the size of OPLL [6][7][8][9][10]. However, these methods involved two-dimensional imaging.…”