Interobserver and intraobserver reliability of the japanese orthopaedic association scoring system for evaluation of cervical compression myelopathy

STUDY DESIGN

The inter- and intraobserver reliabilities of an assessment scale for cervical compression myelopathy were examined statistically. This scoring system consists of seven categories: motor function of fingers, shoulder and elbow, and lower extremity; sensory function of upper extremity, trunk and lower extremity; and function of the bladder. It evaluates the severity of myelopathy by allocating points based on degree of dysfunction in each category.

OBJECTIVES

To determine the inter- and intraobserver reliabilities of the revised scoring system (17 - 2 points) for cervical compression myelopathy proposed by the Japanese Orthopedic Association.

SUMMARY OF BACKGROUND DATA

Several scales to assess clinical outcome from treatment of cervical compression myelopathy have been proposed. Most of these scales include items evaluated by observers. However, no system, including the Japanese Orthopedic Association scoring system, has yet been validated in terms of interobserver reliability.

METHODS

From five different university hospitals, 10 spine surgery specialists, 10 orthopedic surgeons who had just passed the board examination of the Japanese Orthopedic Association, and 13 residents in the first or second year of orthopedic residency programs were chosen. The participants in this study were 29 patients with myelopathy secondary to ossification of the posterior longitudinal ligament selected from five participating university hospitals. Several surgeons interviewed each patient twice at intervals of 1 to 6 weeks. Inter- and intraobserver reliabilities of the total score for all categories were evaluated by the intraclass correlation coefficient. The extension of the kappa coefficient of Kraemer also was calculated for each category to assess reliability of multivariate categorical data.

RESULTS

The interobserver reliability of the total score for the first interview (intraclass correlation coefficient = 0.813) and the intra- and interobserver reliabilities of the total score (intraclass correlation coefficient = 0.826) were high. The level of experience and the hospital slightly affected the reliability of the Japanese Orthopedic Association scoring system. The kappa values for intraobserver data generally were high in each category, whereas the kappa values for interobserver data were relatively low for the categories of shoulder-elbow motor function and lower extremity sensory function.

CONCLUSIONS

The inter- and intraobserver reliabilities of the Japanese Orthopedic Association scoring system for cervical myelopathy were high, suggesting that this system is useful for assessment of cervical myelopathy in comparative studies of treatment.

Functional impact of human collagen alpha2(XI) gene polymorphism in pathogenesis of ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament (OPLL) of the spine is the leading cause of myelopathy in Japan. In earlier studies, we provided genetic linkage and allelic association evidence of distinct differences in the human collagen alpha2(XI) gene (COL11A2) that might constitute inherited predisposition to OPLL. In the present study, a strong allelic association with non-OPLL (p = 0.0003) was observed with an intron 6 polymorphism [intron 6 (-4A)], in which the intron 6 (-4A) allele is more frequently observed in non-OPLL subjects than in OPLL patients. In addition, a newly identified polymorphism in exon 6 [exon 6 (+28A)] was in linkage disequilibrium with the intron 6 (-4A). The functional impact of the polymorphisms was analyzed by comparing the differences in messenger RNA (mRNA) splicing by reverse-transcription polymerase chain reaction (RT-PCR) analysis in cultured cells from the interspinous ligament and an in vitro exon trapping study. The intron 6 (-4A) allele resulted in skipping exon 6 and retaining exon 7, while the exon 6 (+28A) allele was not associated with alteration in mRNA splicing. Similar mRNA species were observed in undifferentiated osteoblast (Ob) cells and in cells from posterior longitudinal ligament of non-OPLL subjects. The region containing exons 6-8 is an acidic subdomain presumably exposed to the surface that could interact with molecules of the extracellular matrix. Accordingly, retaining exon 7 together with removal of exon 6 observed in intron 6 (-4A) could play a protective role in the ectopic ossification process because the same pattern was observed in undifferentiated Ob cells and nonossified posterior longitudinal ligament cells.

Bone mineral density in patients with ossification of the posterior longitudinal ligament in the cervical spine

Bone mineral density (BMD) has not been clearly determined in patients with ossification of the posterior longitudinal ligament (OPLL) in the cervical spine. BMD in patients with OPLL was measured in the third vertebral body in the lateral projection and in the distal part of the radius in the anteroposterior projection using dual-energy X-ray absorptiometry (DXA). Patients with OPLL had significantly higher BMD than healthy controls in both the lumbar spine and radius. Observing BMD by gender and age group, high BMD was recognized especially in female patients over 60 years of age. Significantly increased BMD was observed in patients with ankylosing spinal hyperostosis (ASH) in addition to OPLL. These findings suggest that patients with OPLL may tend to develop systemic hyperostosis, leading to the pathological ectopic ossification observed in OPLL.

Genetic mapping of ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament of the spine (OPLL) is recognized as a common disorder among Japanese and throughout Asia. Estimates of its prevalence are in the range of 1. 9%-4.3%. Although its etiology is thought to involve a multiplicity of factors, epidemiological and family studies strongly implicate genetic susceptibility in the pathogenesis of OPLL. In this study we report an identification of a predisposing locus for OPLL, on chromosome 6p, close to the HLA complex. The evidence for this localization is provided by a genetic-linkage study of 91 affected sib pairs from 53 Japanese families. In this sib-pair study, D6S276, a marker lying close to the HLA complex, gives evidence for strongly significant linkage (P = .000006) to the OPLL locus. A candidate gene in the region, that for collagen 11A2, was analyzed for the presence of molecular variants in affected probands. Of 19 distinct variants identified, 4 showed strong statistical associations with OPLL (highest P = .0004). These observations of linkage and association, taken together, show that a genetic locus for OPLL lies close to the HLA region, on chromosome 6p.

Retinoid and bone metabolic marker in ossification of the posterior longitudinal ligament

The pathogenesis of ossification of the posterior longitudinal ligament (OPLL) remains to be elucidated, though etiologic factors for OPLL have been identified. High levels of serum retinol and retinol binding protein (RBP) have been observed in patients with diffuse idiopathic skeletal hyperostosis (DISH). OPLL is often associated with DISH. In this study, the levels of serum retinol and RBP were determined in 70 patients with OPLL in the cervical spine, and compared with those in normal subjects. Bone metabolic markers of serum intact osteocalcin, urinary pyridinoline and deoxypyridinoline were examined as well. Among female patients, level of serum RBP was significantly higher in those in their 60's, and those with mixed type OPLL. Level of serum RBP was significantly higher in both sexes, and retinol was exhibited higher in female patients, if they were associated with DISH. Patients with OPLL exhibited no abnormal bone metabolic marker levels. These findings suggest that vitamin A may play a role in the development of OPLL.

3-dimensional computed tomography of ossification of the spinal ligament

Ossification of the posterior longitudinal ligament in the cervical spine was studied 3-dimensionally using computed tomography scans of 32 patients. The images produced were classified into 3 types based on the posterior configuration of the ossification: (1) plank shaped, (2) spindle shaped, or (3) rod shaped. Lesions with radiographically continuous and mixed type ossification on 3-dimensional computed tomography were plank shaped or spindle shaped. Rod shaped type lesions usually were radiographically segmented or showed some other type of ossification. The 3-dimensional computed tomography images change with the growth of ossification. Plank shaped type lesions appear to be the final result of ossification. Three-dimensional computed tomography scans of ossification of the longitudinal ligament are useful for decompressive surgery, providing valuable information regarding the site of concentration of compression of the spinal cord or nerve roots and the choice of surgical procedures.

Restriction fragment length polymorphism of genes of the alpha 2(XI) collagen, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha among patients with ossification of posterior longitudinal ligament and controls from the Japanese population

STUDY DESIGN

The present study analyzed the restriction fragment length polymorphism patterns of alpha 2(XI) collagen, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha genes in patients with ossification of the posterior longitudinal ligament. This study investigates the genetic polymorphism of bone-induced factors in patients with ossification of the posterior longitudinal ligament and compares it with healthy control subjects.

OBJECTIVES

To clarify the genetic markers linked to ossification of the posterior longitudinal ligament.

SUMMARY OF BACKGROUND DATA

Ossification of the posterior longitudinal ligament is a genetic disease associated with abnormal calcium metabolism involving the posterior longitudinal ligament. Previous genetic studies have not identified the pathologic mechanism of ossification of the posterior longitudinal ligament. Histopathologic studies of ossification of the posterior longitudinal ligament and the animal model, the spinal hyperostotic mouse, have revealed an increase in Type XI collagen and bone morphogenetic protein-2 expression.

METHODS

Eighteen Japanese patients with ossification of the posterior longitudinal ligament and 51 healthy, unrelated control subjects were investigated for the restriction fragment length polymorphism patterns of COL11A2, bone morphogenetic protein-2, alkaline phosphatase, and tumor necrosis factor-alpha, genes with various restriction endonucleases.

RESULTS

The gene frequencies of COL11A2 obtained with BamHl (10.0 kb fragment) and HindIII (19.0 kb fragment) observed in patients with ossification of the posterior longitudinal ligament were higher compared with control subjects (0.43 and 0.14, respectively). These differences were statistically significant (BamHl P = 0.018; Hindlll P = 0.046). Two new restriction fragment length polymorphism patterns were detected of the bone morphogenetic protein-2 gene with Mspl and Taql and one already known restriction fragment length polymorphism pattern of the tumor necrosis factor-alpha gene with Ncol. However, they were not significantly different from the control subjects.

CONCLUSIONS

Seven restriction fragment length polymorphisms of COL11A2 gene were identified. Two of them (BamHl, 10.0/10.0 kb genotype; HindIII, 19.0/19.0 kb genotype) were significantly different in patients with ossification of the posterior longitudinal ligament.

Effects of strain distribution in the intervertebral discs on the progression of ossification of the posterior longitudinal ligaments

STUDY DESIGN

Strain distribution in the intervertebral discs was evaluated biomechanically using an engineering true strain calculation formula.

OBJECTIVES

This study was performed to clarify the involvement of dynamic factors in the progression of ossification of the posterior longitudinal ligament.

SUMMARY OF BACKGROUND DATA

In patients with ossification of the posterior longitudinal ligament of the cervical spine, ossification frequently progresses after laminectomy. This suggests the involvement of dynamic factors in the progression of ossification. However, these factors have not yet been clarified.

METHODS

The analysis was performed on 101 patients with ossification of the posterior longitudinal ligament by employing dynamic lateral x-ray films of the cervical spine. The x-ray films were digitized and used as computer data for calculating the strain distribution. X-ray films were obtained again 5 years later, and the strain distribution and the presence or absence of progression of ossification were evaluated.

RESULTS

The progression of ossification of the posterior longitudinal ligament was highly correlated with abnormal strain distribution in the intervertebral discs. Progression of ossification was frequently observed in areas having disc distortion in tension and extension on the posterior longitudinal ligament.

CONCLUSIONS

In this study, the area of progression of ossification corresponded to the area showing uneven strain distribution and resultant concentration of dynamic stress. These results suggest an important role for dynamic factors in the progression of ossification of the posterior longitudinal ligament.

Occipitocervical fusion by Luque loop rod instrumentation in Down syndrome

Four children with Down syndrome who had developed atlantoaxial dislocation and myelopathy underwent occipitocervical fusion with Luque loop rod instrumentation and decompressive laminectomy of C1. The postoperative results are presented and the indications discussed. This procedure provides many advantages in the surgical treatment of Down syndrome compared with the conventional procedures, because of the associated mental retardation that makes the postoperative management very complicated.

Potent stimulation of murine B cells to proliferate and to secrete immunoglobulins by a lipoteichoic acid-like molecule produced by Clostridium botulinum C and D

Bacterial products have served as important immunological tools to study lymphocyte activation. The lipopolysaccharides of the Gram-negative bacteria are well known to be potent activators of B lymphocytes. Several Gram-positive bacteria produce exotoxins that are superantigens for T cells. In the present study, we demonstrate that the Gram-positive bacteria Clostridium botulinum C and D produce a high molecular weight mitogen (Cb mitogen) that is a potent activator of murine B lymphocytes. The Cb mitogen was discovered as a consequence of our attempt to investigate a possible superantigen activity present in the botulinum exotoxins. We observed initially that mouse spleen cells were strongly stimulated to proliferate by culture supernatants of C. botulinum C and D. However, the characterization of the responding cell ruled out superantigen because only the B lymphocytes were stimulated to proliferate and to secrete immunoglobulins, and they did so independent of T cell help. In addition, the molecular characterization of the Cb mitogen demonstrated that the purified botulinum toxin was devoid of mitogenic activity. In contrast, the fractionation of the culture supernatant of C. botulinum C in an FPLC Superose 12 column indicated that the Cb mitogen was present in the void volume of the column (MW > or = 300 kDa) which had no toxigenic activity. However, the fractions containing molecules of 150 kDa were highly toxic for mice and had no mitogenic activity. The possibility that LPS was present as a contaminant in the Cb mitogen preparations was excluded because spleen cells from the LPS non-responder C3H/HeJ mice responded well to the Cb mitogen, and the antibiotic polymyxin B, which is an inhibitor of LPS, had no effect on the Cb-mitogen activity. However, an anti-lipoteichoic acid monoclonal antibody (3-1 mAb) inhibited to a great extent the proliferation of spleen cells induced by the Cb mitogen but had no effect on the LPS or concanavalin A stimulation of these cells. Moreover, the Cb mitogen was specifically adsorbed and eluted from a protein G Sepharose column to which the anti-lipoteichoic acid 3-1 mAb had been conjugated. These results support the view that lipoteichoic acid is a selective B cell mitogen.

Histochemical and immunohistochemical study on the skin of patients with ossification of the posterior longitudinal ligament in the cervical spine

We present an immunohistochemical study on extracellular matrix (ECM), decorin, in the epidermis and dermis of patients with ossification of the posterior longitudinal ligament (OPLL) to clarify the abnormality in the extracellular matrix of the skin of OPLL. Localization of decorin and TGF-beta in the skin was studied. All patients with OPLL showed a diffuse strong staining of decorin in the entire epidermal layer. The epidermis was also positive for TGF-beta antibody staining. Patients with cervical spondylotic myelopathy showed weak or no staining of decorin. Abnormality in the regulating system of TGF-beta may be involved in the precipitation of extracellular matrix.

Transpedicular fixation of the lumbar and lumbosacral spine with screws. Application of the Diapason system

Forty-six patients with the Diapason transpedicular screw system for lumbar and lumbosacral fusions were analysed clinically. No implant breakage was observed, but one rod migrated. Additional sacral screws different in the length of the threaded portion are necessary in this system. Metallosis was noted in a few cases, but posed no significant clinical problems. This system, which is simple in structure, easy to use, and applicable to magnetic resonance scanning after surgery, is considered to be a useful instrumentation.

The natural course of myelopathy caused by ossification of the posterior longitudinal ligament in the cervical spine

The natural course of ossification of the posterior longitudinal ligament, particularly the relationship between the onset of myelopathy and factors associated with its aggravation, was studied in 207 patients during an average period of 10 years 3 months. Myelopathic signs were already present in 37 (18%) patients at the time of the initial examination. Fourteen of these 37 patients showed aggravation of symptoms during the observation period. Myelopathy appeared during the observation period in 33 (16%) of the 207 patients. One hundred thirty-seven (66%) patients were free of myelopathy. Some patients had no myelopathic signs, despite severe spinal stenosis, because of the ossification. In these patients, the range of motion of the cervical spine was severely limited, indicating that dynamic factors are important in the development of myelopathy. In treating this disease, it is necessary to take into consideration the natural course of the disease and to identify the involvement not only of static factors, such as compression caused by ossification, but also of dynamic factors.

Comparison of operative results of lumbar disc herniation in manual laborers and athletes

The results of various surgical treatments for lumbar disc herniation in laborers and athletes were compared on the basis of the relative success of return to work and athletic activity. The rate of successful return to manual labor was the highest at 89% after spinal fusion, but no difference was observed between simple disc excision and percutaneous discectomy. Return to competitive sports was achieved at rate of 81% after percutaneous discectomy, and the time until return to sports activity was significantly shorter than after other procedures. In individuals whose lumbar region is expected to be subjected to great mechanical stress, it is important to take work needs and the special needs of athletes into consideration when selecting the surgical procedure.

Genetic study of ossification of the posterior longitudinal ligament in the cervical spine with human leukocyte antigen haplotype

To evaluate the genetic background of ossification of the posterior longitudinal ligament, the relationship between the presence of absence of ossification and human leukocyte antigen haplotypes was studied in 33 families of patients with ossification of the posterior longitudinal ligament. The study revealed that human leukocyte antigen haplotypes formed certain types of clusters, and that some human leukocyte antigen haplotypes were very rare in the Japanese population, suggesting the involvement of human leukocyte antigen-linked factors in the pathogenesis of ossification of the posterior longitudinal ligament of the cervical spine. In the families of these patients, ossification of the posterior longitudinal ligament was demonstrated by radiography in 56% (10/18) of the siblings. Each of these siblings shared both human leukocyte antigen haplotypes with the patient. None of those who shared only one human leukocyte antigen haplotype with the patient had developed ossification of the posterior longitudinal ligament. From these findings, the presence of both pathogenic human leukocyte antigen haplotypes is considered to be necessary for the development of ossification of the posterior longitudinal ligament, and this genetic predisposition may be activated by multiple factors, including regressive degeneration due to aging and the environment.