Longer time of implantation using the buried pin technique for intramedullary nailing would decrease refracture in the diaphyseal forearm fracture in children-retrospective multicenter (TRON) study.

BACKGROUND: Intramedullary nailing using Kirschner wires in pediatric diaphyseal forearm fractures is often performed as a less invasive treatment than plate fixation, but it remains controversial whether the tips of Kirschner wires are buried or exposed. The purpose of this study was to investigate the relationship between whether the tips are buried or exposed and complications, especially of refracture. METHODS: Data of 405 patients under 16 years who underwent surgical treatment for diaphyseal forearm fractures in our 11 hospitals between 2010 and 2020 were collected. Finally, 143 patients who underwent intramedullary nailing with at least 6-month follow-up were analyzed. We investigated difference in complication rates depending on whether the Kirschner wire tips were buried (Group B: n = 79) or exposed (Group E: n = 64). Regarding refractures, we also examined time of onset and status of bone union before the refracture occurred. RESULTS: The duration before implant removal in Group B was more than 4 times longer than that in Group E (mean 187.9 vs. 41.4 days, p<0.001), although there was no significant difference in the progression of bone union between the two groups. Regarding postoperative complications, Group B had a significantly lower rate of refractures than Group E (7.9% vs. 32.8%, p<0.001), although the rate of irritation pain was significantly higher (15.2% vs. 1.6%, p = 0.006). The infection rate was also lower in Group B than Group E, but not significantly so (3.8% vs. 10.9%, p = 0.112). Refractures between 3 and 9 months after surgery accounted for 66.7% of all refractures, and those within 3 months accounted for 14.5% of all fractures. There was no significant difference in the status of bone union before the refracture occurred between patients with and without refracture. CONCLUSIONS: The present study showed that longer time of implantation using the buried pin technique for intramedullary nailing reduces refracture of pediatric diaphyseal forearm fractures. Because of the risk of refracture during remodeling, we recommend the implantation of intramedullary nailing for 6-9 months and the instruction for the patients and the parents to pay more attention to refracture at least within 9 months postoperatively. LEVEL OF EVIDENCE: Level Ⅲ, Multicenter retrospective study.

Comparison of surgical treatments for distal ulna fracture when combined with anterior locking plate fixation of distal radius in the over 70 age group.

We conducted a retrospective multicentre study to compare the clinical and radiographic outcomes, and complications of three surgical treatments of distal ulna fracture (DUF) when combined with anterior locking plate fixation for distal radial fracture (DRF) in patients over 70 years of age. We identified 1521 patients over 70 years of age who were diagnosed as having DRF and who underwent anterior locking plate fixation between 2015 and 2020, among which 122 cases of DUF were analysed. Three surgical treatment options for DUF were identified in this cohort: K-wire fixation (Group K), locking plate fixation (Group L) and Darrach procedure (Group D). The results of the analysis showed the total immobilization period in Group D to be the shortest among the three treatments. Functional outcomes were superior, and the rate of complications were smaller in Group D than in Group L. In addition, rotational range of motion was larger in Group D and Group L compared with Group K. In patients who are 70 years of age or older with combined unstable DRF and highly comminuted or displaced DUF, the Darrach procedure for DUF seems to be the most useful and reasonable treatment option once the fracture of the distal radius has been rigidly fixed.Level of evidence: IV.

Laterality of lumbar disc herniation.

BACKGROUND: Lumbar disc herniation (LDH) is most common in men aged 20-40 at the L4/5 level; however, left-right differences have not been reported. Improving our understanding of left- and right-side LDH may facilitate the estimation of mechanical load on intervertebral discs. Here, we assessed left-right differences in LDH via a retrospective analysis of LDH cases. METHODS: Among 10,972 surgical cases of LDH identified in the Nagoya Spine Group database, 2899 in which right- and left-LDH sides were observable in a single vertebral segment were identified (mean age 46.3 ± 16.6 years, 2028 males). The following characteristics of patients with right- and left-LDH were compared: age, LDH level, surgical technique, operative time, blood loss, length of hospital stay, preoperative Japan Orthopaedic Association (JOA) score, and JOA recovery rate. RESULTS: LDH occurred on the right and left sides in 1358 and 1541 patients, respectively, with patients with right-side LDH significantly older than those with left (47.9 ± 16.6 versus 45.0 ± 16.5, respectively; p < 0.001). No between-group differences in sex, age, LDH level, surgical technique, operative time, blood loss, length of hospital stay, preoperative JOA score, or JOA recovery rate were observed. The occurrence of right-side LDH increased with age, occurring in 42.7%, 45.1%, 49.9%, and 54.7% of patients aged 10-29, 30-49, 50-69, and 70-89 years, respectively. CONCLUSION: Left-side LDH was observed more frequently than right; however, right-side LDH incidence increased with age. No significant between-group differences regarding symptoms, treatments, or outcomes were observed.

What factors are associated with loss of alignment after open reduction and internal fixation for tibial plateau fractures? A retrospective multicenter (TRON group) study.

BACKGROUND: Tibial plateau fractures (TPFs) are one of the most challenging intra-articular fractures to treat. Along with reconstruction of the articular surfaces, appropriate alignment of the knee joints must be obtained and maintained after open reduction and internal fixation (ORIF) for TPFs because loss of alignment (LA) is associated with worse clinical outcomes. We aimed to investigate and clarify the risk factors related to LA after ORIF for TPFs. METHODS: This multicenter, retrospective cohort study used data of hospitals of the Trauma Research Group (TRON group) from January 1, 2011, to December 31, 2020. Among 293 TPFs extracted from the database, we evaluated the alignment of the articular surface to the anatomical axis of the tibia in the immediate postoperative and last follow-up radiographs. We defined a change of alignment from the immediate postoperative radiograph as LA. We evaluated the risk factors of LA using univariate and multiple logistic regression analyses. RESULTS: LA was observed in 27 fractures (9.2%). In multiple logistic regression analyses, preoperative articular step-off and postoperative condylar widening were statistically associated with LA (OR = 1.1, 95% CI: 1.02-1.19 and P = 0.012; OR = 1.04, 95% CI: 1.00-1.08, P = 0.045, respectively). We calculated the threshold by drawing a receiver operating characteristic curve using the final regression model. The threshold of postoperative widening was 8.2 mm. We divided the 293 TPFs into two groups according to this threshold and determined differences between the two groups using Fisher's exact test. The two groups were statistically significantly different (P = 0.00502). CONCLUSIONS: Preoperative articular step-off and postoperative condylar widening could be associated with LA after ORIF for TPFs. We suggest that intraoperative restoration of condylar widening is important for the prevention of malalignment following ORIF for TPF.

Adjacent Segment Degeneration after Short-Segment Lateral Lumbar Interbody Fusion (LLIF).

Purpose: To investigate the influence on the adjacent segment degeneration (ASD) of short-segment lateral lumbar interbody fusion (LLIF) at 2 years postoperatively. Methods: Ninety-seven consecutive patients who underwent one- or two-level LLIF were included from two institutions. We diagnosed radiographical adjacent segment degeneration with the appearance of adjacent spondylolisthesis (>3 mm) or deterioration of adjacent disk height (>3 mm) on plain radiographs or decrease of the intervertebral angle (>5 degrees). The differences between the two groups with and without radiographical ASD were investigated using univariate and multivariate analyses to determine the risk factors for ASD. The variables included extent of adjacent decompression, posterior fixation method (open method or percutaneous method), and facet violation on postoperative CT. Results: In total, 19 patients (19.6%) were diagnosed as radiographical ASD 2 years after surgery. Univariate analysis showed that the ASD (+) group had a high frequency of adjacent decompression (21.1 vs. 3.8%, p = 0.035) compared with the ASD (-) group. There were no differences between the two groups in posterior fusion method (percutaneous method 42.1 vs. 57.7%, p = 0.221) or facet joint violation (15.8 vs. 14.1%, p = 0.860). The multivariate analysis found adjacent intervertebral decompression to be a risk factor for ASD 2 years after surgery (odds ratio: 9.95; 95% confidence interval: 1.2-82.1). Conclusions: Adjacent intervertebral decompression was considered to be a potential risk factor for the development of ASD after spinal fusion with LLIF.

Trends in the numbers of spine surgeries and spine surgeons over the past 15 years.

The purpose of this study is to examine trends in spine surgeries at ten facilities over 15 years, and to analyze relationships with the number of spine surgeons at these facilities. The subjects were patients who underwent spine surgery at the ten facilities from 2003 to 2017. Data were collected every year via a questionnaire designed to obtain clinicopathological and surgical information. There were 37,601 spine surgeries (60.2% male) recorded in the registry at 9 facilities in the Nagoya Spine Group (NSG) between 2003 and 2017, with an increase in the annual number of surgeries by 2.4 times over 15 years. On the other hand, the number of spine surgeons has increased by just under 1.5 times. Instrumentation surgeries increased from 959 in 2003 to 2,276 in 2017 (2.3 times). There was a particularly marked increase in surgeries for spinal degenerative disease from 1,075 in 2003 to 2,821 in 2017 (2.6 times). The number of surgeries performed per surgeon increased from 61.4 in 2003 to 102.8 in 2017, while the average number of spine surgeons per hospital increased from 2.6 in 2003 to 3.7 in 2017. In conclusion, with heavier burden on spine surgeons and the major changes in the spine surgery environment, training and increasing surgeons with advanced expertise and skills will become increasingly important.

Risk factors of non-union in Anderson-D'Alonzo type III odontoid fractures with conservative treatment.

OBJECTIVE: The purpose of this study was retrospectively to analyze the risk factors for non-union in Anderson-D'Alonzo type III odontoid fractures with conservative treatment. METHODS: 25 patients with type III fractures were analyzed. Coronal and sagittal tilt as well as sagittal and lateral mass gaps were measured by using computed tomography. RESULTS: The non-union group had significantly higher age, greater coronal tilt and lateral mass gap. Especially, the lateral mass gap was >2 mm in all cases with non-union. CONCLUSIONS: Higher age, coronal tilt, and lateral mass gap were significant risk factors for non-union.

Seasonal variation in incidence and causal organism of surgical site infection after PLIF/TLIF surgery: A multicenter study.

BACKGROUND: Postoperative SSI is a common and potentially serious complication in spine surgery. Seasonal variation occurs in rates of nosocomial infection, with higher rates found in the summer, during which hot, humid conditions may be optimal for proliferation of bacteria. This might also influence the rate of SSI. The purpose of the study was to examine seasonal variation in SSI after PLIF/TLIF surgery, including relationships with experience of surgeons and causal organisms. METHODS: Cases with SSI after PLIF/TLIF surgery at 10 facilities between January 1, 2012, and December 31, 2014 were retrieved from a database. Infection was defined based on CDC guidelines for SSIs. Patients were followed for at least two years after surgery. Surgeries were examined in spring (April-June), summer (July-September), autumn (October-December), and winter (January-March). Seasonal variation and other factors with a potential association with SSIs were evaluated. RESULTS: A total of 1174 patients (607 males, 567 females) who underwent PLIF/TLIF surgery were identified. The operations were PLIF (n = 667), TLIF (n = 443), MIS-PLIF (n = 27), and MIS-TLIF (n = 37). The total SSI rate for the 2-year period was 2.5% (29/1174), and the 2-year average SSI rates for surgeries in each season were spring, 2.6% (7/266); summer, 3.9% (13/335); fall, 1.3% (4/302); winter, 1.8% (5/271). The SSI rate was significantly higher in summer than non-summer (3.9% vs. 1.9%, p < 0.05). SSIs were caused by a variety of pathogens, including Gram-positive cocci, and Staphylococcus aureus was the most common pathogenic organism to cause SSI. CONCLUSION: Seasonality should be taken into account in strategies for SSI prevention, with particular attention on mitigation of increased temperature and humidity in the summer and on infection caused by Gram-positive cocci and S. aureus.

Trends in Reoperation for Surgical Site Infection After Spinal Surgery With Instrumentation in a Multicenter Study.

STUDY DESIGN: A multicenter retrospective analysis of a prospectively maintained database. OBJECTIVE: To examine the characteristics of reoperation for surgical site infection (SSI) after spinal instrumentation surgery, including the efficacy of treatment for SSI and instrumentation retention. SUMMARY OF BACKGROUND DATA: Aging of the population and advances in surgical techniques have increased the demand for spinal surgery in elderly patients. Treatment of SSI after this surgery has the main goals of eliminating infection and retaining instrumentation. METHODS: The subjects were 16,707 patients who underwent spine surgery with instrumentation in 11 hospitals affiliated with the Nagoya Spine Group from 2004 to 2015. Details of those requiring reoperations for SSI were obtained from surgical records at each hospital. RESULTS: There were significant increases in the mean age at the time of surgery (54.6-63.7 years) and the number of instrumentation surgeries (726-1977) from 2004 to 2015. The incidence of reoperation for SSI varied from 0.9% to 1.8%, with a decreasing trend over time. Reoperation for SSI was performed in 206 cases (115 men, 91 women; mean age 63.2 years). The average number of reoperations (1.4 vs. 2.3, P < 0.05), time from SSI to first reoperation (4.3 vs. 9.5 days, P < 0.05), and the methicillin-resistant Staphylococcus identification rate (20% vs. 37%, P < 0.01) were all significantly lower in cases with instrumentation retention (n = 145) compared to those with instrumentation removal (n = 61). CONCLUSION: There were marked trends of aging of patients and an increase in operations over the study period; however, the incidences of reoperation and instrumentation removal due to SSI significantly decreased over the same period. Rapid debridement after SSI diagnosis may have contributed to instrumentation retention. These results can serve as a guide for developing strategies for SSI treatment and for improved planning of spine surgery in an aging society. LEVEL OF EVIDENCE: 3.

A Study of Risk Factors for Early-Onset Adjacent Vertebral Fractures After Kyphoplasty.

STUDY DESIGN: Retrospective study. OBJECTIVES: To elucidate risk factors for early-onset (2 months after initial kyphoplasty) adjacent vertebral fracture (EO-AVF) after kyphoplasty. METHODS: A total of 108 vertebral bodies (95 patients) were included in this study. We examined patient backgrounds, the spinal level of EO-AVFs, surgery-related factors, and imaging findings. We divided the cases into 2 groups: patients with EO-AVF and patients without EO-AVF. Univariate, correlation, and multivariate analyses were conducted to reveal the risks factors for EO-AVFs for these 2 groups. RESULTS: EO-AVFs developed in 28 vertebral bodies; they did not develop in 80 vertebral bodies. The overall EO-AVF incidence rate was 26%. The spinal level was the thoracolumbar junction for 93% of patients and another level for 7%, thus demonstrating the concentration of EO-AVFs in the thoracolumbar junction. For patients without EO-AVF and those with EO-AVF, there were significant differences in age (76 and 80 years, respectively), preoperative vertebral angles (VAs) (17.8° and 23°, respectively), and corrected VAs (7.3° and 12.7°, respectively). Significant differences were not observed for other factors. Pearson's correlation coefficient was 0.661 (P < .000), thereby showing a significantly positive correlation between preoperative VAs and corrected VAs. Logistic regression analysis indicated that age (odds ratio, 1.112; 95% CI, 1.025-1.206) and preoperative VAs (odds ratio, 1.08; 95% CI, 1.026-1.135) were covariates and that the presence of an EO-AVF was a dependent variable. Therefore, both were predictable risk factors for EO-AVFs. CONCLUSION: Age, preoperative VAs, and corrected VAs are risk factors for EO-AVFs after kyphoplasty.

Predictors of Prolonged Length of Stay After Lumbar Interbody Fusion: A Multicenter Study.

STUDY DESIGN: Retrospective analysis of a prospectively database. OBJECTIVES: To identify factors associated with prolonged length of stay (LOS) in posterior /transforaminal lumbar interbody fusion (PLIF/TLIF). METHODS: The subjects were patients who underwent PLIF/TLIF at 10 facilities from 2012 to 2014. A total of 1168 such patients with a mean age of 65.9 ± 12.5 years (range 18-87 years) were identified in the database. Operations were PLIF (n = 675), TLIF (n = 443), minimally invasive surgery (MIS)-PLIF (n = 22), and MIS-TLIF (n = 32). Age, gender, body mass index, ambulatory status, comorbidities, perioperative American Society of Anesthesiologists (ASA) grade, operative factors, and complications were examined. LOS was defined as the number of calendar days from the operation to hospital discharge. LOS was categorized as normal (<75th percentile) or prolonged (≥75th percentile). RESULTS: The average LOS was 20.8 ± 9.8 days (range 7-77 days). There was a significant correlation between LOS and age (P < .05). Reoperation during hospitalization was performed in 20 cases for surgical site infection (n = 12), epidural hematoma (n = 5), and screw misplacement (n = 3). In multivariate analysis, prolonged LOS was associated with preoperative variables of age ≥70 years (odds ratio [OR] 1.87, 95% CI 1.38-2.54), and ASA class ≥III (OR 1.52, 95% CI 1.04-2.25); surgical variables of open procedures (OR 5.84, 95% CI 1.74-19.63), fused levels ≥3 (OR 5.17, 95% CI 3.17-8.43), operative time ≥300 minutes (OR 1.88, 95% CI 1.15-3.07), and estimated blood loss ≥500 mL (OR 1.71, 95% 1.07-2.75). CONCLUSIONS: The factors identified in this study should help with obtaining informed consent, surgical planning and complication prevention to reduce health care costs associated with prolonged LOS.

Trends of postoperative length of stay in spine surgery over 10 years in Japan based on a prospective multicenter database.

OBJECTIVES: To identify factors associated with prolonged length of stay (LOS) in spine surgery, with the goal of establishing details of LOS for multiple diseases and surgical procedures. PATIENTS AND METHODS: The subjects were patients who underwent spine surgery at 10 facilities in the Nagoya Spine Group from January 2005 to December 2015. Data were collected for patient background, primary spinal pathology, anatomical location of the lesion, and surgical methods. The primary outcome was LOS, which was defined as the calendar days from surgery to hospital discharge. RESULTS: A total of 10,829 patients (5953 males, 4876 females; age 5-93 years, mean 60.2 ± 28.8 years) were identified in the database. Average follow-up was 61 months (range: 13-120 months). Average LOS was 22.3 ± 21.3 days, and there was a gradual decrease in LOS over the study period. LOS was significantly correlated with age, and prolonged LOS was significantly associated with thoracic spine surgery and significantly longer after surgery with instrumentation. Average LOS was >30 days for intramedullary tumor resection and posterior cervical fusion, but only 10.2 days for microendoscopic discectomy. Reoperation was performed in 210 patients (1.9%) and these patients had a significantly higher average LOS of 43.1 days. CONCLUSION: These results will assist quality improvement in spine surgery. The identified risk factors for prolonged LOS will also assist in planning of surgery, postoperative care, and discharge, with the goal of reducing health care costs.

Postoperative Complications Associated With Spine Surgery in Patients Older Than 90 Years: A Multicenter Retrospective Study.

STUDY DESIGN: A review of a prospective database. OBJECTIVES: Surgery for elderly patients is increasing yearly due to aging of society and the desire for higher quality of life. The goal of the study was to examine perioperative complications in spine surgery in such patients. METHODS: A multicenter study of surgical details and perioperative complications was performed in 35 patients aged older than 90 years who underwent spinal surgery, based on a review of a prospective database. The frequency and severity of complications were assessed, and the effects of patient-specific and surgical factors were examined. Major complications were defined as those that were life threatening, required reoperation in the perioperative period or left a permanent injury. Ambulatory function before and after surgery was also analyzed. RESULTS: Perioperative complications occurred in 19 of the 35 cases (54%), and included 11 cases of postoperative delirium, most of which occurred after cervical spine surgery. There were 8 major complications (23%), including cerebral infarction (n = 3), coronary heart disease (n = 3), pulmonary embolism (n = 1), and angina (n = 1). Preoperative motor deficit, operative time, estimated blood loss, and instrumented fusion were significantly associated with major complications. An improved postoperative ambulatory status occurred in 61% of cases, with no change in 33%, and worsening in 2 cases (6%). CONCLUSIONS: Timing of surgery before paralysis progression and reduced surgical invasiveness are important considerations in treatment of the very elderly. Improved outcomes can be obtained with better management of spine surgery for patients aged 90 years or older.

Reoperation within 2 years after lumbar interbody fusion: a multicenter study.

PURPOSE: Posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) can have complications that require reoperation. The goal of the study was to identify risk factors for reoperation within 2 years after PLIF/TLIF. METHODS: A retrospective analysis of a prospective multicenter database was performed for patients who underwent PLIF/TLIF. A total of 1363 patients (689 males and 674 females) were identified, with an average age of 65.9 years old. Comorbidities, perioperative ASA grade, and operative factors were compared between patients with and without reoperation. Risk factors for reoperation were identified in multivariate logistic analysis. RESULTS: There were 38 reoperations within 2 years after PLIF/TLIF (2.8%). The original surgical procedures were open PLIF (n = 26), open TLIF (n = 10), and minimally invasive surgery (n = 2). Reoperation was due to adjacent segment degeneration (ASD) (n = 10), surgical site infection (SSI) (n = 9), screw misplacement (n = 6), postoperative epidural hematoma (n = 6), pseudoarthrosis (n = 4), and cage protrusion (n = 3). Number of levels fused and dural tear were significantly associated with reoperation. In analysis of complications requiring reoperation, SSI was related to diabetes mellitus and dural tear, and postoperative epidural hematoma was related to fusion of two or more levels, EBL, and operation time. In multivariate logistic regression, fusion of two or more levels (HR 2.19) was significantly associated with reoperation. CONCLUSION: Surgical invasiveness, as reflected by number of fused levels, operation time, EBL and dural tear, was associated with reoperation. Fusion of two or more levels is a strong risk factor for reoperation within 2 years after initial PLIF/TLIF. These slides can be retrieved under Electronic Supplementary Material.

Radiographic Adjacent Segment Degeneration at 5 Years After L4/5 Posterior Lumbar Interbody Fusion With Pedicle Screw Instrumentation: Evaluation by Computed Tomography and Annual Screening With Magnetic Resonance Imaging.

STUDY DESIGN: Retrospective clinical study. OBJECTIVE: To investigate adjacent segment degeneration (ASD) at 5 years after L4/5 posterior lumbar interbody fusion with pedicle screw instrumentation and L4/5 decompression surgery using plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI), with the evaluation of annual changes on MRI. SUMMARY OF BACKGROUND DATA: Methods of evaluation have been inconsistent among studies of ASD. There is no report that ASD in the lumbar spine after posterior lumbar interbody fusion at the same level is thoroughly evaluated on radiographs, CT, annual MRI changes, and the impact of decompression procedures. METHODS: ASD was evaluated in 52 patients. Disk height, vertebral slip, intervertebral angle, and intervertebral range of motion were examined on plain radiographs. Facet joint degeneration on CT and disk degradation and spinal stenosis on MRI were classified into categories, and facet sagittalization and tropism were measured on CT. The incidence of ASD was compared between the decompression procedures. RESULTS: The radiographic changes observed in the study were defined as radiographic ASD (R-ASD) without reoperation, as no patient required reoperation. R-ASD was rarely detected by radiography. The incidences of facet joint degeneration, MRI-detected disk degeneration, and spinal stenosis at the L3/4 and L5/S1 levels were 21% and 23%, 27% and 17%, and 35% and 4%, respectively. Progressive disk degeneration at L3/4 was found significantly more frequently in patients with aggravation of facet degeneration (P<0.01); however, the severities of preoperative facet degeneration, facet sagittalization, and tropism were not associated with progressive disk degeneration or spinal stenosis. In annual MRI, most R-ASD cases were detected within 3 years after surgery. Patients who underwent L4 total laminectomy had significantly more frequent R-ASD compared with those who received bilateral fenestration at L4/5 (P<0.01). CONCLUSIONS: R-ASD was detected more frequently by CT and MRI compared with radiography. Preoperative facet joint degeneration and morphology were not always related to progressive disk degeneration or spinal stenosis. Annual MRI suggested that accelerated degeneration was due to lumbar spine fusion, rather than aging degeneration. Decompression with preservation of posterior connective components is recommended to prevent R-ASD.

Appropriate timing of surgical intervention for the proximal type of cervical spondylotic amyotrophy.

PURPOSE: The purposes of this study were to evaluate the clinical outcome after surgical treatment of patients with the proximal type of cervical spondylotic amyotrophy (CSA) and to explore the appropriate timing for surgical intervention. MATERIALS AND METHODS: A retrospective review was performed on a consecutive cohort of 41 patients who underwent surgical treatment for the proximal type of CSA between 1995 and 2011 at the Nagoya Spine Group Hospitals. We collected information regarding age, type of muscle atrophy, preoperative and final manual muscle test, duration of symptoms, high-intensity areas on T2-weighted MRI images, low-intensity areas on T1-weighted MRI images, levels of spinal canal stenosis, the compression lesion site, cervical kyphosis and surgical procedures (laminoplasty, anterior spinal fusion and posterior spinal fusion). Univariate analyses and multivariate logistic regression analysis were performed to identify correlates of a poor outcome. To explore the appropriate timing for performing surgery, we analyzed the data using receiver operating characteristic (ROC) analysis. RESULTS: The duration of CSA symptoms was 11.6 months on average. The surgical results were excellent for 25 patients, good for six, fair for nine and poor for one. On multivariate logistic regression analysis, the duration of symptoms was statistically associated with a poor surgical outcome (OR 1.393, p = 0.011). ROC analysis demonstrated that 4.3 months from the onset of CSA symptoms was the appropriate time to undergo surgery. CONCLUSIONS: Our results indicate that we should recommend surgical intervention to patients with the proximal type of CSA within about 4 months after the onset of symptoms if conservative treatment has not been successful.

Intradural disc herniation: radiographic findings and surgical results with a literature review.

OBJECTIVE: To report a series of four cases of intradural disc herniation (IDH) with a review of the literature. SUMMARY OF BACKGROUND DATA: IDH is a rare type of disc herniation. Preoperative diagnosis is difficult and IDH is only confirmed during surgery in most cases. Here, we describe four cases of IDH, including three with lumbar hernia and one with thoracic hernia. METHODS: A retrospective chart review, surgical database query, and review of radiology reports are presented for each case, along with a literature review of IDH. RESULTS: Two of the four patients had a history of surgery at the same spinal level. Ring enhancement in gadolinium-enhanced MRI, an air image in computed tomography, and complete block in myelography were observed in the series. Surgery was performed with a transdural approach in all patients. One patient underwent transforaminal lumbar interbody fusion after postoperative recurrence. Three patients with lumbar involvement had nerve root symptoms preoperatively, but showed symptomatic improvement in the early postoperative period. In contrast, the patient with thoracic involvement had preoperative muscle weakness due to myelopathy symptoms, and had residual symptoms after surgery. CONCLUSIONS: IDH is a rare disease and characteristic imaging findings can be useful for diagnosis. Intraoperative findings lead to a definitive diagnosis in many cases and recognition of the pathological characteristics of IDH is important.

Predictive factors for a poor surgical outcome with thoracic ossification of the ligamentum flavum by multivariate analysis: a multicenter study.

STUDY DESIGN: Retrospective multi-institutional study. OBJECTIVE: The purpose of this study was to describe the surgical outcomes in patients with ossification of the ligamentum flavum (OLF) and determine the influence of an ossified anterior longitudinal ligament (OALL) on the clinical features and surgical outcomes in thoracic OLF. SUMMARY OF BACKGROUND DATA: Detailed analyses of surgical outcomes of thoracic OLF have been difficult because of rarity of this disease. METHODS: We identified 96 patients (77 males and 19 females with a mean age at surgery of 63.4 ± 10.3 yr) who underwent surgery for thoracic OLF and investigated their preoperative symptoms, severity of symptoms and myelopathy, disease duration, magnetic resonance imaging and computed tomographic findings, surgical procedure, intraoperative findings, and postoperative recoveries. The presence of OALL found at or near the most severely affected OLF level on sagittal computed tomographic images was classified into 1 of the following 4 types: (1) "no discernible type" (type N); (2) "one-sided type" (type O); (3) "discontinuous type" (type D); and (4) "continuous type" (type C). Multivariate logistic regression analysis was used to compute odds ratios and 95% confidence intervals to identify the risk factors associated with surgical outcomes. RESULTS: The mean Japanese Orthopaedic Association score was 5.6 points preoperatively and 7.8 points 2 years postoperatively, yielding a mean recovery rate of 44.6%. Disease duration, presence of ossified dura mater, and type D OALL were the important factors for predicting surgical outcomes. CONCLUSION: After evaluating surgical outcomes on the largest sample size of OLF surgical procedures thus far, our results show that disease duration, ossification of the dura mater, and the presence of type D OALL were risk factors related to surgical outcomes. LEVEL OF EVIDENCE: 3.

Risk factors for a poor outcome following surgical treatment of cervical spondylotic amyotrophy: a multicenter study.

INTRODUCTION: Cervical spondylotic amyotrophy (CSA) is characterized by muscle atrophy in the upper extremities without gait disturbance. However, the indications and outcomes of surgical treatment for CSA have not been clarified. The purpose of this study was to determine the risk factors for a poor outcome following surgical treatment of CSA. MATERIALS AND METHODS: We performed a retrospective review of CSA in patients from 1991 to 2010 through a multicenter study. We collected information regarding age, type of muscle atrophy, preoperative manual muscle test (MMT), duration of symptoms, high-intensity areas on T2-weighted MR images, low-intensity areas on T1-weighted MR images, levels of spinal canal stenosis, cervical kyphosis and surgical procedures (laminoplasty, anterior cervical discectomy and fusion and posterior spinal fusion), and calculated overall risk factors related to a poor outcome following surgery. Univariate analyses and multivariate logistic regression analysis were performed to identify correlates of a poor outcome. RESULTS: Fifty-nine patients, 95 % male (56 patients), were included in our analysis with a mean age of 59 years (range 32-78 years). Eighteen patients did not improve after surgery. Symptom duration (OR = 1.263), preoperative MMT grade (OR = 0.169) and distal type of CSA (OR = 9.223) were all associated with an increased risk of a poor surgical outcome. CONCLUSION: Early surgery is recommended for CSA patients in whom conservative treatment has not been successful. We also recommend surgery for patients who have severe preoperative muscle weakness or have the distal type of CSA.