Ossification of the posterior longitudinal ligament of the cervical spine: etiology and natural history.

STUDY DESIGN: Review article. OBJECTIVE: To review the etiology, natural history, measurement tools, and image diagnosis of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. SUMMARY OF BACKGROUND DATA: OPLL is a well-known disease that causes myelopathy. Genetic factors are very important for development of OPLL. However, the pathogenetic gene and natural history of OPLL have not been clarified. METHODS: The authors reviewed studies about the etiology, natural history, measurement tools, and diagnosis of OPLL, which had been performed by the members of the Investigation Committee on the Ossification of the Spinal Ligaments of the Japanese Ministry of Health, Labour, and Welfare. RESULTS: The prevalence of OPLL in the general Japanese population was reported to be 1.9% to 4.3% among people older than 30 years. Genetic factors are important for development of OPLL, and some candidate genes have been reported. Clinical course of OPLL has been clarified by a prospective long-term follow-up study. Some radiographic predictors for development of myelopathy were introduced. Image diagnosis of OPLL is easy by plain radiographs, but magnetic resonance imaging and computed tomography are useful to determine cord compression by OPLL. CONCLUSION: OPLL should be managed on the basis of the consideration of its natural history. Elucidation of pathogenetic genes of OPLL will introduce a new approach for management of OPLL.

Long-term result of combination of open reduction and femoral derotation varus osteotomy with shortening for developmental dislocation of the hip.

This study examined femoral derotation varus osteotomy with shortening performed on children with developmental dislocation of the hip. Each patient reached 14 years of age. Surgical outcomes were evaluated clinically and roentgenographically. We studied nine patients with 11 joints undergoing surgical repair. Age at the time of operation averaged 2 years and 1 month; the period of observation averaged 15 years and 7 months; and age at final investigation averaged 17 years and 8 months. Each patient underwent the study operation as an initial treatment. Salter pelvic osteotomy was reserved as a second treatment for those patients whose acetabular development proved inadequate during post-surgical observation. The evaluation method established by McKay was utilized to determine clinical results at the time of final investigation; 73% of the study group were established as having good results. Severin's evaluation method was used to assess roentgenographical results; 45% of the study group were determined to have good results. Kalamchi's evaluation method allowed six joints to be diagnosed with avascular necrosis of the femoral head; however, in all cases but one, necrosis had been present prior to surgery. Those six joints that did not have necrosis of the femoral head prior to surgery developed only one mild necrosis subsequent to surgery. Achieving a stable reduced position by femoral derotation varus osteotomy, as well as sufficient decompression of the femoral head by shortening osteotomy, are considered to have played very important roles in preventing the femoral head from developing necrosis.

Clinical course of patients with ossification of the posterior longitudinal ligament: a minimum 10-year cohort study.

OBJECT: Ossification of the posterior longitudinal ligament (OPLL) may produce quadriplegia. The course of future neurological deterioration in patients with radiographic evidence of OPLL, however, is not known. The authors conducted a long-term follow-up cohort study of more than 10 years to clarify the clinical course of this disease progression. METHODS: A total of 450 patients, including 304 managed conservatively and 146 treated by surgery, were enrolled in the study. All patients underwent neurological and radiographical follow-up examinations for a mean of 17.6 years. Myelopathy was graded using Nurick classification and the Japanese Orthopaedic Association scale. Fifty-five (17%) of 323 patients without myelopathy evident at the first examination developed myelopathy during the follow-up period. Risk factors associated with the evolution of myelopathy included greater than 60% OPLL-induced stenotic compromise of the cervical canal, and increased range of motion of the cervical spine. Using Kaplan-Meier analysis, the myelopathy-free rate in patients without first-visit myelopathy was 71% after 30 years. A significant difference in final functional outcome was not observed between nonsurgical and surgical cases in which preoperative Nurick grades were 1 or 2. In patients with Nurick Grade 3 or 4 myelopathy, however, only 12% who underwent surgery eventually became wheelchair bound or bedridden compared with 89% of those managed conservatively. Surgery proved ineffective in the management of patients with Grade 5 disease. CONCLUSIONS: Results of this long-term cohort study elucidated the clinical course of OPLL following conservative or surgical management. Surgery proved effective for the management of patients with Nurick Grades 3 and 4 myelopathy.

Occupational recovery after open-door type laminoplasty for patients with ossification of the posterior longitudinal ligament.

STUDY DESIGN: A cross-sectional survey of occupational recovery after surgery with patients who had ossification of the posterior longitudinal ligament. OBJECTIVES: To evaluate occupational recovery after open-door type laminoplasty for patients with ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: The literature contains numerous reports on the surgical results of laminoplasty for ossification of the posterior longitudinal ligament, but very few reports are available on postoperative quality of life, and even fewer on occupational recovery after laminoplasty. METHODS: A cross-sectional survey was conducted of 301 patients with ossification of the posterior longitudinal ligament in the cervical spine who were employed before open-door type laminoplasty. Presurgical occupations were classified into three categories: light sedentary labor, light standing labor, and heavy labor. High-rise workers and professional drivers were analyzed separately. The subjects were rated by occupational category for determining the occupational recovery ratio. Factors analyzed for impact on recovery were pre- and postsurgery severity of myelopathy, duration of myelopathy, age at surgery, gender, and type of ossification of the posterior longitudinal ligament. RESULTS: Of the 301 patients studied, 160 (53%) returned to work. Poor recovery rates were observed for heavy labor, high-rise workers, and professional drivers. The period required for return to work did not significantly differ among occupational categories. Occupation, presurgery severity of myelopathy, and postsurgery severity of myelopathy were significantly correlated with occupational recovery. CONCLUSION: Patients' occupations should be carefully considered when designing postsurgery occupational rehabilitation programs, and patients should receive postoperative advice regarding the suitability of occupation.

Prognosis of patients with upper cervical lesions caused by rheumatoid arthritis: comparison of occipitocervical fusion between c1 laminectomy and nonsurgical management.

STUDY DESIGN: A matched controlled comparative study of patients with upper cervical lesions caused by rheumatoid arthritis was performed at two different hospitals to evaluate occipitocervical fusion associated with C1 laminectomy and nonsurgical treatment. OBJECTIVES: To evaluate the long-term results and advantages of occipitocervical fusion associated with C1 laminectomy, and to compare these results with those of nonsurgical management of patients with myelopathy related to rheumatoid arthritis. SUMMARY OF BACKGROUND DATA: Few studies have reported the prognosis of patients with rheumatoid arthritis managed by occipitocervical fusion associated with C1 laminectomy. METHODS: In this study, 40 patients with rheumatoid arthritis and myelopathy caused by irreducible atlantoaxial dislocation with or without upward migration of the odontoid process were studied. Of these 40 patients, 19 were treated by occipitocervical fusion using a rectangular rod associated with C1 laminectomy at one hospital, whereas 21 matched patients were treated conservatively at another hospital. The patients were observed by the same protocol to assess the radiologic and clinical results, including functional recovery and survival rate. All the patients were followed until their death. RESULTS: The atlantodental interval was reduced immediately after surgery, and this result had been well maintained at the final follow-up assessment. Redlund-Johnell values did not vary significantly throughout the course of the study. As for neural assessment with the Ranawat classification system, improvement was found in 13 (68%) of the 19 patients who underwent surgery. The survival rate was 84% 5 years after surgery, and 37% in the first 10 years. In the patients who did not undergo surgical treatment, atlantodental interval and Redlund- Johnell values were aggravated. These patients showed no neural improvement, and aggravation was found in 16 (76%) of the 21 cases during the follow-up period. All the patients were bedridden within 3 years after the onset of myelopathy. The survival rate was 0% in the first 8 years. CONCLUSIONS: The findings lead to the conclusion that occipitocervical fusion associated with C1 laminectomy for patients with rheumatoid arthritis is useful for decreasing nuchal pain, reducing myelopathy, and improving prognosis.

Pathogenesis of myelopathy in patients with ossification of the posterior longitudinal ligament.

OBJECT: The goal of this study was to clarify the pathogenesis of myelopathy in patients with ossification of the posterior longitudinal ligament (OPLL) based on the relationship between static compression factors and dynamic factors. METHODS: There was a total of 247 patients, including 167 patients who were conservatively followed for a mean of 11 years and 2 months and 80 patients who had myelopathy at initial consultation and underwent surgery. The changes in clinical symptoms associated with OPLL in the cervical spine were examined periodically. During the natural course of OPLL in the cervical spine, 37 (22%) of 167 patients developed or suffered aggravated spinal symptoms. All of the patients with a space available for the spinal cord (SAC) less than 6 mm suffered myelopathy, whereas the patients with an SAC diameter of 14 mm or greater did not. No correlation was found between the presence or absence of myelopathy in patients whose SAC diameter ranged from 6 mm to less than 14 mm. In patients with myelopathy whose minimal SAC diameter ranged from 6 mm to less than 14 mm, the range of motion of the cervical spine was significantly greater. CONCLUSIONS: These results indicate that pathological compression by the ossified ligament above a certain critical point may be the most significant factor in inducing myelopathy, whereas below that point dynamic factors may be largely involved in inducing myelopathy.

Trauma-induced myelopathy in patients with ossification of the posterior longitudinal ligament.

OBJECT: In these prospective and retrospective studies the authors evaluated trauma-induced myelopathy in patients with ossification of the posterior longitudinal ligament (OPLL) to determine the effectiveness of preventive surgery for this disease. METHODS: The authors studied 552 patients with cervical OPLL, including 184 with myelopathy at the time of initial consultation and 368 patients without myelopathy at that time. In the former group of 184 patients retrospective analysis was performed using an interview survey to ascertain the relationship between onset of myelopathy and trauma. In the latter group of 368 patients prospective examination was conducted by assessing radiographic findings and noting changes in clinical symptoms apparent during regular physical examination. The follow-up period ranged from 10 to 32 years (mean 19.6 years). In the retrospective investigation, 24 patients (13%) identified cervical trauma as the trigger of their myelopathy. In the prospective investigation, 70% of patients did not develop myelopathy over a follow-up period greater than 20 years (determined using the Kaplan-Meier method). Of the 368 patients without myelopathy at the time of initial consultation, only six patients (2%) subsequently developed trauma-induced myelopathy. Types of ossification in patients who developed trauma-induced myelopathy were primarily a mixed type. All patients in whom stenosis affected 60% or greater of the spinal canal developed myelopathy regardless of a history of trauma. CONCLUSIONS: Preventive surgery prior to onset of myelopathy is unnecessary in most patients with OPLL.