Clinical Significance of Improved Intraoperative Neurophysiological Monitoring Signal during Spine Surgery: A Retrospective Study of a Single-Institution Prospective Cohort.

STUDY DESIGN: Retrospective case series. PURPOSE: We reviewed the cases that showed significant improvement of intraoperative neurophysiological monitoring (IONM) signals during spine surgery to assess whether there is a correlation with signal improvement and postoperative clinical status and its clinical significance. OVERVIEW OF LITERATURE: To reduce the risk of neural injury, many spine surgeons are using multimodality IONM. Although many studies attempted to identify valid alarm criteria for predicting postoperative neurologic deterioration, studies concerning the improvement of IONM signals are rare. METHODS: We reviewed all spine surgery cases with IONM data treated at our department between January 2013 and May 2017. We found cases showing significant IONM signal improvements. We prospectively analyzed the neurological and clinical outcomes of these patients and compared outcomes pre- and postoperatively. RESULTS: Among 317 cases with the IONM data, we found 29 cases that showed IONM signal improvement compared with baseline. There were 27 cases of compressive myelopathy: 22 had a degenerative cause at the cervical spine, and five, at the thoracic spine. There were two cases of huge neurogenic tumor each at the craniovertebral junction and at the lumbar spine. Both motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SSEPs) signals were improved in six cases, only the MEPs signal improved in 10, and only SSEP signal improved in 13 cases. All cases showed the IONM signal improvement consistently after the decompression procedure during surgery. All patients had a significant improvement in neurological function and subjective symptoms, and none had neurologic deterioration postoperatively. CONCLUSIONS: Improvement of IONM signals during surgery may indicate that no unrecognized neural injury occurred during surgery and a favorable postoperative neurological outcome can be expected.

Restoration of the Spinous Process Following Muscle-Preserving Posterior Lumbar Decompression via Sagittal Splitting of the Spinous Process.

BACKGROUND: In lumbar spinal stenosis, spinous process-splitting decompression has demonstrated good clinical outcomes with preservation of the posterior ligamentous complex and paraspinal muscles in comparison to conventional laminectomy, but the radiological consequence and clinical impact of the split spinous processes have not been fully understood. METHODS: Seventy-three patients who underwent spinous process-splitting decompression were included. The bone union rate and pattern were evaluated by computed tomography performed 6-18 months after surgery and compared among subgroups divided according to the number of levels decompressed and the extent of spinous process splitting. The bone union pattern was classified into three categories: complete union, partial union, and nonunion. The visual analog scale (VAS) score, Oswestry disability index (ODI), and walking distance assessed both before and 24-36 months after surgery were compared among subgroups divided according to the union pattern of the split spinous process. RESULTS: Overall, the rates of complete union, partial union, and nonunion were 51.7%, 43.2%, and 5.1%, respectively. In the subgroup with partial splitting of the spinous process, the rates were 85.7%, 14.3%, and 0%, respectively; those of the subgroup with total splitting of the spinous process were 32.9%, 59.2%, and 7.9%, respectively. With single-level decompression, a higher rate of union was observed compared with multilevel decompression. The VAS, ODI, and walking distance were significantly improved after surgery and did not differ according to the degree of union of the split spinous process. CONCLUSIONS: We found that the single-level operation and partial splitting of the spinous process were favourable factors for obtaining complete restoration of the posterior bony structure of the lumbar spine in spinous process-splitting decompression.

Infection following percutaneous vertebral augmentation with polymethylmethacrylate.

Although the incidence of infection following vertebroplasty or kyphoplasty is rare, postoperative infection and cement augmentation in preexistent spondylitis can cause life-threatening complications in frail patients with notable comorbidities. In such cases, urgent culture and biopsy and the long-term use of proper antibiotics are necessary. PURPOSE: Infection following vertebral augmentation with polymethylmethacrylate (PMMA) is rare. We aimed to analyze 11 cases of pyogenic spondylitis and spondylodiscitis that occurred after vertebroplasty or kyphoplasty and to review similar cases in the literature. METHODS: All cases of postoperative spinal infections in our institution between January 2005 and November 2016 that primarily underwent percutaneous vertebroplasty or kyphoplasty were retrospectively reviewed. Eleven patients (mean age 76.3 years) were included. RESULTS: The incidence of infection following vertebroplasty/kyphoplasty was 0.36%. Postoperative infection occurred in 3 of 826 cases. All patients underwent combined surgical and antibiotic treatment because of neurologic deficit on the initial diagnosis of the infection or failure of prior medical treatment of the infection. The surgical procedure was thorough debridement of infected tissue and material including PMMA following anterior column reconstruction via anterior/posterior/combined approach in 10 patients and percutaneous pedicle screw fixation alone in 1 patient aged 96 years. The mean follow-up period was 21.1 months after the revision operation, excluding one patient who died 17 days after revision surgery. Ten patients recovered from infection. CONCLUSIONS: Although the incidence of infection following vertebroplasty or kyphoplasty is rare, postoperative infection and cement augmentation in preexisting spondylitis can develop into a life-threatening complication in frail patients with notable comorbidities. In treating infected vertebroplasty and kyphoplasty, immediate culture and biopsy and the long-term use of proper antibiotics are critical. Prompt surgical treatment should be considered in case of significant neurologic deficit, severe instability due to infected fracture, and resistance to antibiotics.

Mortality following benign sacral insufficiency fracture and associated risk factors.

This study demonstrated increased mortality following sacral insufficiency fractures as with other major osteoporotic fractures. The 6-month mortality rate was 9.8%, the 1-year mortality rate was 17.5%, and the 3-year mortality rate was 25.5%. Sex- and age-adjusted standardized mortality ratio increased after fractures. INTRODUCTION: There are no data about mortality after sacral insufficiency fractures. The purposes of this study were to investigate the mortality rate among sacral insufficiency fracture patients and to identify risk factors associated with mortality. METHODS: This is a retrospective cohort study of patients diagnosed with sacral insufficiency fracture via radiological exam in a single institute from 2001 to 2014, excluding patients with pathological sacral fracture due to metastasis or primary tumor. Mortality and its predisposing factors were analyzed based on a review of electronic medical records and mortality data provided by the Korean Statistical Information Service. Kaplan-Meier survival analysis and Cox regression analysis were used for statistical analysis. RESULTS: A total of 325 patients were included (275 women and 50 men). The mean age at the time of diagnosis was 69.4 years. One hundred and forty patients (43.1%) had a history of malignancy, and 71 patients (21.8%) had undergone pelvic radiation therapy before fracture diagnosis. Twenty-one patients (6.5%) underwent sacroplasty, and the others underwent conservative management after fracture diagnosis. The mean follow-up was 51.5 months, and a total of 101 patients died at the final follow-up. The 6-month mortality rate was 9.8%, the 1-year mortality rate was 17.5%, and the 3-year mortality rate was 25.5%. Sex- and age-adjusted standardized mortality ratio (SMR) increased after fractures. The overall SMR is 8.9 at 3 months decreasing to 4.5 at 2 years. Multivariable Cox regression analysis showed that significant factors associated with increased mortality were male gender, malignancy history, lumbosacral fusion with distal fusion level S1, stroke history, low total femur bone mineral density score, and low body mass index. CONCLUSIONS: Like other types of osteoporotic fractures, sacral insufficiency fractures are associated with increased mortality.

Diagnostic Value of Technetium-99m Bone Scintigraphy in the Detection of Cervical Spine Metastases in Oncological Patients.

MINI: Bone scan remains the modality of choice for the screening of bone metastases. This study demonstrated the diagnostic value of bone scan in detecting bone metastases limited to the cervical spine in oncological patients remains uncertain due to the moderately high false-negative diagnostic rate. STUDY DESIGN: A retrospective cohort, radiographic study. OBJECTIVE: To assess the diagnostic accuracy of bone scintigraphy (BS) for the detection of cervical spine metastases in oncological patients. SUMMARY OF BACKGROUND DATA: BS remains the modality of choice for the screening of bone metastases, because of its feasibility in whole-body scanning and its widespread availability at low cost. Current practice guidelines for patients with malignant diseases recommend BS imaging as the primary screening method for detecting both axial and appendicular skeletal metastases. METHODS: Of 481 patients, 242 were diagnosed with cervical spinal metastases from a primary cancer. The BS findings of these patients, evaluated by nuclear medicine physicians, were assessed with respect to their usefulness for detecting cervical spine metastases. Magnetic resonance imaging findings, evaluated by radiologists, were used as the reference standards. The diagnostic value of BS was compared between subgroups according to the order in which the diagnostic procedures (magnetic resonance imaging and BS) were completed, the presence of pathological fractures, the location of the primary malignancy, and the number of cervical metastases. RESULTS: The sensitivity of BS in the detection of cervical spine metastases was 59.1%, with a 40.9% rate of false-negative diagnoses; the specificity was 94.6%, with a 5.4% rate of false-positive diagnoses. The sensitivity tended to be higher in the presence of pathological fractures (72.1% in cases with a fracture vs. 3% in cases without a fracture) and a greater number of lesions (r = 0.921). Neither the order in which the diagnostic examinations were performed nor the location of the primary cancer, except for those in the stomach and liver, appeared to affect the diagnostic accuracy of BS. CONCLUSION: Considering the moderately high false-negative diagnostic rate obtained in the present study, BS alone cannot accurately diagnose metastases in the cervical spine in oncological patients. LEVEL OF EVIDENCE: 3.

Asymmetry of the cross-sectional area of paravertebral and psoas muscle in patients with degenerative scoliosis.

PURPOSE: This study was undertaken to assess the change of psoas and paravertebral muscles in patients with degenerative scoliosis. METHODS: Eighty-five patients with degenerative scoliosis were evaluated with simple radiography for the location and direction of the apex of scoliosis, coronal Cobb's angle, rotational deformity and lumbar lordosis, and with magnetic resonance imaging scan at the apex level of each patient, the cross-sectional area (CSA) and the fatty infiltration rate (FI) of bilateral paravertebral and psoas muscles were measured and the values of convex and concave side were compared. RESULTS: Fifty-three patients had apex of curves on the left side and thirty-two patients on the right. The mean Cobb's angle was 17.9°. The difference index of CSA (CDI) of psoas and multifidus muscle at apex of curvature level was significantly larger in convex side rather than that in concave side (by 6.3 and 8.4 % with P = 0.019 and 0.000, respectively). FI of each muscle showed no significant difference. CONCLUSIONS: Hypertrophy of the muscles on the convex side is suggested as the explanation of this asymmetry rather than atrophy of the muscles on the concave side as muscle atrophy is known to be associated with increased fatty infiltration.

Evaluation of vitamin D level and grip strength recovery in women with a distal radius fracture.

PURPOSE: Vitamin D is known to contribute to muscular function. The purpose of this study was to determine whether the level of vitamin D is associated with grip strength recovery in women after a distal radius fracture. METHODS: We analyzed grip strength recovery after a distal radius fracture in 70 women over age 50 years. We measured vitamin D levels and grip strength recovery, which we analyzed as a function of age, surgical care, baseline vitamin D level, vitamin D supplementation, wrist range of motion, pain level, and radiographic results at 6 months. We performed multivariate analysis to identify factors that independently predicted grip strength recovery at 6 months after injury. RESULTS: Grip strength of affected hands averaged 65% of the contralateral sides (range, 25% to 100%) at 6 months after injury. We found no significant correlation between baseline vitamin D level and grip strength recovery. However, baseline vitamin D level correlated with the grip strengths of uninjured sides. Multivariate analysis indicated that younger age, vitamin D supplementation, and greater wrist range of motion were independently associated with better grip strength recovery at 6 months after injury. CONCLUSIONS: This study demonstrated that in women with a distal radius fracture, baseline vitamin D level is not associated with grip strength recovery in the injured hand. However, baseline vitamin D level correlated with grip strength in the uninjured hand. In addition, vitamin D supplementation may help grip strength recovery in the injured hand. Further prospective, comparative studies are warranted to confirm the effect of vitamin D supplementation on grip strength recovery.

Pitfalls and important issues in testing reliability using intraclass correlation coefficients in orthopaedic research.

BACKGROUND: Intra-class correlation coefficients (ICCs) provide a statistical means of testing the reliability. However, their interpretation is not well documented in the orthopedic field. The purpose of this study was to investigate the use of ICCs in the orthopedic literature and to demonstrate pitfalls regarding their use. METHODS: First, orthopedic articles that used ICCs were retrieved from the Pubmed database, and journal demography, ICC models and concurrent statistics used were evaluated. Second, reliability test was performed on three common physical examinations in cerebral palsy, namely, the Thomas test, the Staheli test, and popliteal angle measurement. Thirty patients were assessed by three orthopedic surgeons to explore the statistical methods testing reliability. Third, the factors affecting the ICC values were examined by simulating the data sets based on the physical examination data where the ranges, slopes, and interobserver variability were modified. RESULTS: Of the 92 orthopedic articles identified, 58 articles (63%) did not clarify the ICC model used, and only 5 articles (5%) described all models, types, and measures. In reliability testing, although the popliteal angle showed a larger mean absolute difference than the Thomas test and the Staheli test, the ICC of popliteal angle was higher, which was believed to be contrary to the context of measurement. In addition, the ICC values were affected by the model, type, and measures used. In simulated data sets, the ICC showed higher values when the range of data sets were larger, the slopes of the data sets were parallel, and the interobserver variability was smaller. CONCLUSIONS: Care should be taken when interpreting the absolute ICC values, i.e., a higher ICC does not necessarily mean less variability because the ICC values can also be affected by various factors. The authors recommend that researchers clarify ICC models used and ICC values are interpreted in the context of measurement.