Efficiency of Long Lateral Mass Screws.

Introduction: Lateral mass screws (LMS) have been widely used for the posterior fusion of the cervical spine. Even though LMS are safe, the screws are short and postoperative fixation is uncertain. Therefore, we measured and reported a technique using long lateral mass screws (LLMS), a new method of screw insertion, using a Zed spine from LEXI (Tokyo, Japan). Materials and Methods: In this study, we evaluated the outcomes of 35 patients who underwent surgery using LLMS at our hospital from 2019 to 2021. Operative time, blood loss, complications, inserted screw length, screw length based on gender differences, and screw deviation rate were evaluated. The Mann−Whitney U test was used to determine the gender differences in screw length. Screw deviation was evaluated by postoperative CT and a Zed spine to determine the screw insertion angle. Results: The mean operative time was 185 ± 51 min (120−327 min), and the mean blood loss was 236 ± 316 g (10−1720 g). The total number of screws was 183. The screw length was 22.2 (16−28) mm for males and 20.8 (16−28) mm for females, with an average length of 21 ± 2.7 mm. No gender differences were observed in terms of screw length (p > 0.01 NS). The number of deviated screws above G3 was one in the third cervical vertebra, three in the fourth cervical vertebra, one in the fifth cervical vertebra, and one in the sixth cervical vertebra. The number of deviated screws was 6 out of 183, and the deviation rate was 3.2%. Conclusions: In this study, the LLMS deviation rate was 3.2%, and strong fixation was possible without any complications. We measured the screw length and screw deviation rate in cases in which LLMS were actually inserted.

Surgical Predictors for Prevention of Postoperative Shoulder Imbalance in Lenke Type 2A Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Multicenter, retrospective cohort study. OBJECTIVE: The aim of this study was to investigate the occurrence and surgical predictors of postoperative shoulder imbalance (PSI) in Lenke type 2A adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: Although several studies have investigated the factors influencing PSI in Lenke type 2 curves, no studies have analyzed PSI-related factors considering upper instrumented vertebra (UIV) and lumbar modifier type simultaneously. METHODS: Patients with Lenke Type 2A AIS treated by spinal fusion were retrospectively identified and their data were extracted from six spine centers in Japan. Inclusion criteria were age between 10 and 20 years at surgery, UIV = T2, major curve 40° to 90°, and follow-up for 24 to 30 months after surgery. We analyzed patient characteristics, surgical characteristics, and preoperative and immediate-postoperative radiographic parameters. We defined patients with lower instrumented vertebra (LIV) equal or proximal to the last touching vertebra (LTV) as selective thoracic fusion (STF-LTV) and patients with LIV distal to the LTV as non-STF-LTV. t Tests, Mann-Whitney U test, χ2 tests, Fisher exact tests, and multivariate logistic regression were used for statistical analyses. RESULTS: Among the 99 consecutive patients with a mean follow-up of 25.6 months, PSI was seen in 27 (27.3%) patients immediately after and in 17 (17.2%) patients at 24 to 30 months. The univariate analysis revealed that the significant risk factors of PSI were preoperative radiographical shoulder height, non-STF-LTV, and high main thoracic curve (MTC) correction (immediate-postoperative MTC correction rate: ≥70%), with PSI incidence of 40.0%. The multivariate logistic regression analysis indicated that interaction term of non-STF-LTV and high MTC correction was an independent risk factor for PSI (non-STF-LTV and high MTC correction, odds ratio: 5.167, 95% confidence interval: 1.470-18.159, P = 0.010). CONCLUSION: To prevent PSI in Lenke Type 2A AIS patients, surgeons should avoid the combination of non-STF-LTV and high MTC correction in those surgeries with UIV as T2.Level of Evidence: 4.

The Relationship between the Occipitocervical Junction and Thoracic Kyphosis in Ankylosing Spondylitis: A Retrospective Cohort Study of 86 Cervical Fractures in Surgically Treated Patients.

STUDY DESIGN: Retrospective analysis of prospectively collected data. PURPOSE: To describe the radiological characteristics of the occipitocervical area in patients with ankylosing spondylitis (AS) using the novel measure X-angle and to describe the correlation between the ankylosed occipitoatlantoaxial (OAA) joint and thoracic kyphosis (TK). OVERVIEW OF LITERATURE: AS affects the axial skeleton, leading to progressive ankylosis of all vertebral segments. The effect of ankylosis on the upper cervical area of these patients is not well documented. METHODS: All patients with complete ankylosis of the spinal column between C3 and T1, treated for cervical spinal fracture between 2007 and 2014, were eligible for inclusion in this study. The level of cervical fracture was identified. The T1-12 and T5-12 angles were measured using preoperative lateral radiography. The progressive degeneration of the C0-C1-C2 joints was evaluated via the new indicator X-angle, through the measurement of the angle of the C0-C1-C2 articulations in the coronal plane using computed tomography. RESULTS: We included 86 consecutive patients with AS (67 males) aged 69±12 years. The patients were divided into two groups according to the degenerative change in the C0-C1 joint (62 patients with a mobile joint and 24 patients with an ankylosed joint). There was no significant difference between the two groups in terms of age (p =0.094) and level of fracture (p =0.949). The most commonly affected level was C6. There was no requirement for revision due to non-union in any of the patients. There was a statistically significant difference observed in the T1-12, T5-12, and X-angles (p =0.004, 0.001, and <0.001, respectively). TK was greater in the ankylosed joint group than in the mobile joint group. The X-angle was also greater in the ankylosed joint group because of the vertical destruction of the OAA joint. CONCLUSIONS: Thoracic hyperkyphosis resulted in degenerative changes in the C0-C1-C2 joint in patients with AS. The X-angle is a reliable method for measuring the integrity of the C0-C1-C2 joint in such patients.

Occipitosacral Fusion for Multiple Vertebral Fractures with Kyphotic Deformity in a Patient with Mutilating Rheumatoid Arthritis: A Case Report.

Osteoporotic vertebral fractures are well-known complications of rheumatoid arthritis. The management of multiple vertebral fractures with kyphotic deformity is controversial. We present a case of a patient with mutilating rheumatoid arthritis who had multiple vertebral fractures with kyphotic deformity after occipitothoracic fusion for rheumatoid cervical disorder. Occipitosacral fusion was effective to create stable spine with better sagittal alignment in this case, but careful clinical assessment for early detection and management of postoperative insufficient pelvic fracture were required.

A Japanese nationwide multicenter survey on perioperative complications of corrective fusion for elderly patients with adult spinal deformity.

BACKGROUND: Recently, corrective fusion surgery for patients with adult spinal deformity (ASD) has become common in Japan. This study aimed to clarify the status of surgeries for ASD in Japan, focusing on perioperative complications. A nationwide multicenter survey gathering information on surgically treated ASD patients was conducted by the committee for Adult Spinal Deformity of the Japanese Scoliosis Society. METHODS: This study was a review of retrospectively collected data from 18 spine scoliosis centers belonging to the Japanese Scoliosis Society. Patients who underwent corrective fusion surgery for ASD between 2011 and 2013 were included. Demographics, comorbidities, surgical data, and complications were investigated. RESULTS: A total of 1192 patients (mean age, 57.7 years) were included in this study. Of these, 611 patients were aged less than 65 years and 581 patients were aged 65 years or greater. The age distribution had two peaks, in the third and eighth decades. Deformities caused by degeneration represented 67% of the pathology in patients aged over 65 years; however, non-degenerative disease such as adult idiopathic scoliosis and syndromic or congenital deformity represented over 60% of pathology in patients aged less than 65 years. The iatrogenic deformity and reoperation rates were both less than 3%. The mean operation time and estimated blood loss were 370 min and 1642 ml, respectively. Major perioperative complications occurred in 160 patients (14.5%). The incidence of complications was significantly higher in patients aged over 65 years, including neurological deficits, hemorrhagic shock, hematoma, heart failure, and surgical site infection (p < 0.05). CONCLUSIONS: Older (aged over 65 years) ASD patients showed greater rates of deformity due to the occurrence of degeneration and vertebral fractures, as well as a higher incidence of peri-and postoperative complications. Efforts to reduce perioperative complications are therefore imperative, especially for elderly ASD patients in our aging society.

C7 sagittal vertical axis is the determinant of the C5-C7 angle in cervical sagittal alignment.

BACKGROUND CONTEXT: Previous studies have indicated that the T1 slope correlates with cervical lordosis. In contrast, the specific impact of the C7 sagittal vertical axis (C7SVA) on cervical lordosis remains unknown. PURPOSE: This study aimed to investigate the specific role of C7SVA in cervical lordosis. STUDY DESIGN/SETTING: This was a retrospective radiographic study. PATIENT SAMPLE: Forty-eight consecutive patients who underwent lateral standing radiography of the entire spine were retrospectively reviewed. OUTCOME MEASURES: Radiographic parameters included occipito (Oc)-C7, Oc-C2, C2-C7, C2-C4, and C5-C7 angles; T1 slope; C7SVA; T1 pelvic angle (TPA); pelvic incidence; pelvic tilt; and sacral slope. METHODS: The radiographs of 96 consecutive patients who underwent lateral standing radiography of the entire spine in June 2015 in our hospital were retrospectively reviewed. Patients having cervical deformities, having undergone cervical fusion, and under 18 years of age were excluded. A total of 48 Asian patients (14 men and 34 women; mean age, 54.6 years) were eligible. Pathologies included scoliosis, myelopathy, thoracolumbar deformity, and spondylosis. Spearman rank correlation coefficients were used to examine correlations between the parameters. The relationship between C5-C7 lordosis and the radiographic parameters was calculated using the forward stepwise multivariate regression analysis. The authors do not have financial associations relevant to this article. RESULTS: C7SVA correlated with the Oc-C7 (r=0.42) and C2-C7 (r=0.50) angles. However, the correlation coefficient was smaller than that between the T1 slope and Oc-C7 (r=0.83) or C2-C7 (r=0.76) angles. When the C2-C7 angle was divided into C2-C4 and C5-C7 angles, C7SVA correlated with the C5-C7 (r=0.63) angle but not with the C2-C4 angle. The correlation coefficient between the C5-C7 angle and C7SVA was higher than that between the C5-C7 angle and T1 slope (r=0.53) or the C5-C7 angle and TPA (r=0.60). Using radiographic parameters and age, multiple regression analysis revealed that only C7SVA affected the C5-C7 angle. CONCLUSIONS: C7SVA was the only radiographic parameter that affected the C5-C7 angle. Both T1 slope and C7SVA are key to the shape of the cervical sagittal alignment. The results of this study can be a starting point to improve our understanding of cervical sagittal alignment.

Correlations of Cervical Sagittal Alignment before and after Occipitocervical Fusion.

Study Design Retrospective radiographic study. Objective To investigate changes and correlations of cervical sagittal alignment including T1 slope before and after occipitocervical corrective surgery. We also investigated the relevance for preoperative planning. Methods We conducted a retrospective radiographic analysis of 27 patients who underwent surgery for occipitocervical deformity. There were 7 men and 20 women with a mean age of 56.0 years. Mean follow-up was 68.0 months (range 24 to 120). The radiographic parameters measured before surgery and at final follow-up included McGregor slope, T1 slope, occipito (O)-C2 angle, O-C7 angle, and C2-C7 angle. Pearson correlation coefficient was used to examine the correlation between the radiographic parameters. Results There was a stronger positive correlation between the T1 slope and the O-C7 angle both preoperatively and postoperatively (r = 0.72 and r = 0.83, respectively) than between the T1 slope and the C2-C7 angle (r = 0.60 and r = 0.76, respectively). The O-C2 angle and C2-C7 angle had inverse correlations to each other both pre- and postoperatively (r = - 0.50 and -0.45). McGregor slope and T1 slope did not significantly change postoperatively at final follow-up. Increase in O-C2 angle after surgery (mean change, 10.7 degrees) inversely correlated with decrease in postoperative C2-C7 angle (mean change, 12.2 degrees). As result of these complementary changes, O-C7 angle did not statistically change. Conclusions Our results suggest that the O-C7 angle is regulated by T1 slope and the corresponding O-C7 angle is divided into the O-C2 and C2-C7 angles, which have inverse correlation to each other and then maintain McGregor slope (horizontal gaze).

Clinical and Anatomical Features as well as Pathological Conditions of Surgically Treated Adult Patients with Occipitalization of the Atlas.

BACKGROUND: This paper intends to clarify clinical and anatomical features as well as pathological conditions of surgically treated adult patients with occipitalization of the atlas. METHODS: The authors reviewed 12 consecutive adult patients with occipitalization of the atlas who underwent surgery for myleopathy in our hospital. Mainly using preoperative computed tomography and three-dimensional computed tomography angiography, we investigated their anomalies of the osseous structures and vertebral artery at the cervical spine including the craniovertebral junction (CVJ). We also developed a new classification system for occipitalization of the atlas. RESULTS: Atlantoaxial subluxation (AAS) was detected in 9 patients (75%). The condition of AAS was irreducible in 7 patients. Among these 7 patients, deformity at the lateral atlantoaxial joints was detected in 2 patients. C2-3 fusion was detected in 6 patients (67%) among 9 patients with AAS. Anomalies of the VA were detected in 11 patients (92%). Occipitalization of the atlas was classified into three types according to their pathological conditions. In type 1 (2 patients) the medial atlantoaxial joint is semi-dislocated and the lateral atlantoaxial joints are severely deformed. Type 2 (7 patients) exhibits AAS but the lateral atlantoaxial joints are not deformed. Type 3 (3 patients) is not associated with AAS and therefore does not exhibit osseous stenosis at the CVJ. In type 3 the myelopathy was caused by another coexisting condition. CONCLUSIONS: Occipitalization of the atlas is classified into three types. The main pathological condition in both types 1 and 2 is AAS. Reduction of AAS is essential in both; however, reduction of AAS in type 1 is more technically demanding than in type 2. The pathological conditions of type 3 are completely different from those of the others, so an accurate diagnosis must be made. The new classification system is a useful guide for surgeons when planning surgical strategies.

Distal Junctional Disease after Occipitothoracic Fusion for Rheumatoid Cervical Disorders: Correlation with Cervical Spine Sagittal Alignment.

Study Design Retrospective radiographic study. Objective We have performed occipitothoracic (OT) fusion for severe rheumatoid cervical disorders since 1991. In our previous study, we reported that the distal junctional disease occurred in patients with fusion of O-T4 or longer due to increased mechanical stress. The present study further evaluated the association between the distal junctional disease and the cervical spine sagittal alignment. Methods Among 60 consecutive OT fusion cases between 1991 and 2010, 24 patients who underwent O-T5 fusion were enrolled in this study. The patients were grouped based on whether they developed postoperative distal junctional disease (group F) or not (group N). We measured pre- and postoperative O-C2, C2-C7, and O-C7 angles and evaluated the association between these values and the occurrence of distal junctional disease. Results Seven (29%) of 24 patients developed adjacent-level vertebral fractures as distal junctional disease. In group F, the mean pre- and postoperative O-C2, C2-C7, and O-C7 angles were 12.1 and 16.8, 7.2 and 11.2, and 19.4 and 27.9 degrees, respectively. In group N, the mean pre- and postoperative O-C2, C2-C7, and O-C7 angles were 15.9 and 15.0, 4.9 and 5.8, and 21.0 and 20.9 degrees, respectively. There were no significant differences between the two groups. The difference in the O-C7 angle (postoperative angle - preoperative angle) in group F was significantly larger than that in group N (p = 0.04). Conclusion Excessive correction of the O-C7 angle (hyperlordotic alignment) is likely to cause postoperative distal junctional disease following the OT fusion.

A novel skull clamp positioning system and technique for posterior cervical surgery: clinical impact on cervical sagittal alignment.

A prospective radiographic study.The purpose of this study was to analyze whether a novel skull clamp positioning system and technique is useful for obtaining good, quantitative cervical sagittal alignment during posterior cervical surgery.Different surgical procedures depend on cervical spine positioning. However, maneuver of the device and cervical position depends on the skill of the operator.This study included 21 male and 10 female patients with cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament of the cervical spine, undergoing posterior cervical surgery using the novel skull clamp positioning system. The average patient age was 68.6 years (range: 56-87 years). The novel system has a scale to adjust the neck position and to enable intended cervical sagittal alignment. First, the patient was placed on the operating table in the prone position with preplanned head-neck sagittal alignment (neutral position in general). The head was rotated sagittally, and the head was positioned in the military tuck position with the novel device that was used to widen the interlaminar space. After completing the decompression procedure, the head was rotated again back to the initial preplanned position. During this position change, the scale equipped with the device was useful in determining accurate positions. The C0-C1, C0-C2, C1-C2, C2-C7, and C0-C7 angles were measured on lateral radiographs taken pre-, intra-, and postoperatively.This novel system allowed us to obtain adequate, quantitative cervical sagittal alignment during posterior cervical surgery. There were no clinically significant differences observed between the pre- and postoperative angles for C1-C2 and C2-C7.Sagittal neck position was quantitatively changed during posterior cervical surgery using a novel skull clamp positioning system, enabling adequate final cervical sagittal alignment identical to the preplanned neck position.

Japanese orthopaedic association back pain evaluation questionnaire (JOABPEQ) as an outcome measure for patients with low back pain: reference values in healthy volunteers.

BACKGROUND: In 2007, the Japanese orthopaedic association back pain evaluation questionnaire (JOABPEQ) was established to overcome the limitations of the original JOA scoring system developed in 1986. Although this new self-administered questionnaire is a more accurate outcome measure for evaluating patients with low back pain, physicians were unable to as certain the exact status of a patient at a single time point because of a lack of reference values. This study aimed to establish the reference values of JOABPEQ in different age and gender groups using data obtained from healthy volunteers. METHODS: This study was conducted in 21 university hospitals and affiliated hospitals from October 2012 to July 2013. The JOABPEQ includes 25 questions that yield five domains to evaluate individuals with low back pain from five different perspectives. A total of 1,456 healthy volunteers (719 men, 737 women; age range, 20-89 years) answered the questionnaire. The differences in scores according to age and gender were examined by non-parametric tests. RESULTS: The JOABPEQ scores significantly decreased with age in the domains of lumbar spine dysfunction, gait disturbance, and social life dysfunction. In these three domains, the median scores approached the 100 possible points in individuals aged 20-70 for both genders. However, the median scores for lumbar spine dysfunction and social life dysfunction decreased to 83.0 and 65.0-78.0 points, respectively, in individuals in their 80 s and 70-80 s, respectively; and the scores for gait disturbance decreased to 93.0 and 71.0 points for males and females in their 80 s. Overall, the median scores for pain-related and psychological disorders were 100 and 60.0-72.0 points, respectively. CONCLUSION: The reference values for JOABPEQ according to age and gender were established herein. Patients with low back pain should be evaluated with this new self-administered questionnaire taking these reference values into account.

An outcome measure for patients with cervical myelopathy: the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ): an average score of healthy volunteers.

BACKGROUND: An outcome measure to evaluate the neurological function of patients with cervical myelopathy was proposed by the Japanese Orthopaedic Association (JOA score) and has been widely used in Japan. However, the JOA score does not include patients' satisfaction, disability, handicaps, or general health, which can be affected by cervical myelopathy. In 2007, a new outcome measure, the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), which is a self-administered questionnaire, was developed. However, the influence of age and gender on the scores has not been fully examined. The purpose of this study was to establish the standard value of the JOACMEQ by age using healthy volunteers. METHODS: This study was conducted in 23 university hospitals and their affiliated hospitals from September to December 2011. The questionnaire included 24 questions for evaluation of physical function of the cervical spine and spinal cord. A total of 1,629 healthy volunteers were recruited for the study. The ages ranged from 20 to 89 years old. RESULTS: The volunteers comprised 798 men and 831 women. In the elderly healthy volunteers, the JOACMEQ scores decreased with age. In general, the scores for cervical spine function and upper/lower extremity function were retained up to the 60s, then decreased in the 70s and 80s. The scores for quality of life were retained up to the 70s; however, the score for bladder function was retained up to the 40s, then declined with age from the 50s to 80s. CONCLUSION: The standard values of the JOACMEQ by age were established. Differences in the scores were found among different generations. Patients with cervical myelopathy should be evaluated with this new self-administered questionnaire taking into account the standard values according to different ages.

Adjacent-level failures after occipito-thoracic fusion for rheumatoid cervical disorders.

INTRODUCTION: The natural history of cervical spine lesions in rheumatoid arthritis (RA) is variable. We have actively performed occipito-thoracic fusion for severe destructive rheumatoid cervical disorders and reported its clinical results and complications. In our previous study, the most frequent complication was the adjacent-level failures caused by the fragile spine. The objective of this study was to determine risk factors for adjacent-level failures after occipito-thoracic fusion. MATERIALS AND METHODS: Subjects were 35 RA patients (31 females and 4 males) who underwent occipito-thoracic fusion using RRS Loop Spinal System(®) (Robert Reid Inc. Tokyo, Japan), and the incidence and characteristics of adjacent-level failures were investigated. Furthermore, the adjacent-level failures were divided into two types according to their levels, fracture at the lowest level of the fusion area and that at the level inferior to the fusion area, and the characteristics of each type were evaluated. RESULTS AND CONCLUSION: Nine (26%) of 35 patients suffered adjacent-level failures (10 vertebral fractures). Adjacent-level failures occurred when the distance of fixation was "O-T4" or longer. The long fusion might cause adjacent-level failures due to greater mechanical stress. Seven fractures occurred at the lowest level of the fusion area, and all of them were cured without symptoms by conservative treatment. Three fractures occurred at the level inferior to the fusion area, and one of them needed additional surgery due to sudden paraplegia resulting from collapse of the adjacent vertebra. After occipito-thoracic fusion, burst fractures at the level inferior to the fusion area might cause sudden paraplegia, and therefore a careful observation should be required for patients with these fractures.

Neurological improvement and prognosis after occipito-thoracic fusion in patients with mutilating-type rheumatoid arthritis.

INTRODUCTION: Mutilating-type rheumatoid arthritis, the most aggressive type of rheumatoid arthritis, is frequently associated with destructive cervical involvement, both at the high-cervical and subaxial levels, causing significant neurological deficit, and their natural course of the disease and the survival are discouraging. For such cases, we have been actively performing occipito-thoracic fusion since 1991. Although medical treatment for rheumatoid patients has represented a marked improvement, it could not treat all of these patients because of several reasons. Therefore, it is still important to evaluate the past treatment results. METHODS: We investigated the neurological improvement and prognosis in 51 mutilating-type rheumatoid arthritis patients who underwent occipito-thoracic fusion between 1991 and 2010. The neurological status was evaluated using modified Ranawat classification; class IIIB was subdivided into IIIBa (able to sit upright) and IIIBb (bedridden). RESULTS: The preoperative neurologic status was IIIBa in 19 patients and IIIBb in 17 patients. 15 of the 19 patients with class IIIBa improved to being able to walk (79 %), whereas only 3 of the 17 patients with class IIIBb improved to being able to walk (18 %) after surgery. Of the 51 patients, 28 died during follow-up; the mean age at death was 67.2 years. The postoperative 5- and 10-year survival rates were 60.3 and 26.4 %, respectively. CONCLUSION: The neurological improvement and prognosis after surgery was poorer in class IIIBb patients than in the other patient groups. Occipito-thoracic fusion can improve the neurological symptoms and prognosis. However, early surgical intervention is recommended, before a patient becomes bedridden (class IIIBb).

Diagnostic validity of space available for the spinal cord at C1 level for cervical myelopathy in patients with rheumatoid arthritis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate diagnostic validity of space available for the spinal cord (SAC) at C1 level for myelopathy in patients with rheumatoid arthritis (RA). SUMMARY OF BACKGROUND DATA: The relationship of SAC at C1 level with myelopathy has been evaluated by relatively small number of the patients, and 2 criteria have been proposed. METHODS: Two cohorts of the patients with RA were established. Group A consisted of 140 patients with myeopathy due to upper cervical involvement selected from the database. Group B consisted of 99 patients with upper cervical subluxation, but not associated with myelopathy selected from the consecutive series of the hospitalized patients. Distributions of SAC at C1 level in both groups were evaluated. Efficacy indexes for screening (sensitivity, specificity, etc.) were calculated for these patients' population by previously demonstrated 2 criteria. In addition, analysis according to receiver operating characteristic (ROC) curve was performed. RESULTS: The average values of SAC were 11.1 mm in Group A and 16.5 mm in Group B. When cut-off point for myelopathy was defined as 13 mm or less, sensitivity and specificity were 82% and 85%, respectively. When it was defined as 14 mm or less, sensitivity increased (88%) while specificity decreased (74%). Accuracies by these 2 criteria were almost the same (83%, 82%). The left upper corner point of ROC curve was located between these 2 cut-off points. CONCLUSION: Distributions of SAC showed that SAC was a reliable parameter for relating myelopathy in patients with upper cervical subluxation in RA. The plots according to ROC curve showed adequacy of previously demonstrated 2 cut-off points. For the purpose to screen the patients with high risk for myelopathy, 14 mm or less was recommended as a cut-off point of SAC.

Clinical results after cervical laminoplasty: differences due to the duration of wearing a cervical collar.

OBJECTIVE: This investigation assessed the relationship between the duration of wearing a cervical collar and clinical results in patients undergoing laminoplasty. METHODS: Twenty-five patients with cervical myelopathy who underwent laminoplasty and wore a cervical collar for 8 weeks postoperatively were followed for an average of 27.3 months. A second group of 26 patients who underwent laminoplasty and wore a cervical collar for 4 weeks was followed for an average of 32.8 months. RESULTS: In both groups, neurologic recovery rate and range of motion on lateral cervical radiographs were longitudinally compared with those obtained preoperatively. There was no significant difference in neurologic recovery between the two groups. In patients who wore the cervical collar for 4 weeks, the total range of the cervical spine was better maintained, especially the extension range of the cervical spine, compared with that in the patients who wore the cervical collar for 8 weeks. CONCLUSIONS: It is speculated that early removal of the cervical collar prevents contracture of the facet joint and postoperative atrophy and dysfunction of the extensor musculature of the cervical spine.