Gabriel Liu

Anterior Cervical Fusion Assessment : Surgical Exploration Versus Radiographic Evaluation

Study Design. Prospective clinical trial. Objective. The goal of this prospective study was to assess the reliability of plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) to detect a pseudarthrosis after an anterior cervical fusion compared with intraoperative exploration. Summary of Background Data. Although anterior cervical fusions have been performed for >50 years, diagnosis of pseudarthrosis remains controversial, and even though various radiologic methods have been described to detect a pseudarthosis, no reports have compared these studies against the gold standard of intraoperative exploration to determine which is most accurate. Methods. All explorations were performed >6 months after the index procedure and studies were obtained within a month of surgery. Indications for reoperation were adjacent level disease and/or pseudarthrosis repair. All patients were thoroughly explored using a microscope, uncinate-to-uncinate exploration, and if necessary, removal of part of the corticalized graft. Radiologic studies were blindly and independently reviewed by 3 spine surgeons uninvolved in the care of the patients. Results. Of the 14 patients included, 8 had pseudarthroses. Assessment of the agreement between intraoperative and radiographic findings revealed a mean Kappa statistic of 0.67 (range, 0.51–0.75, P < 0.05) for plain radiographs, 0.81 (range, 0.71–0.87, P < 0.05) for CT, and 0.48 (range, 0.32–0.71, P < 0.05) for MRI. When all studies were taken into consideration, the mean Kappa statistic increased to 0.85 (range, 0.71–1.00, P < 0.05). Assessment of paired interobserver reliability revealed a mean Kappa statistic of 0.46 (range, 0.31–0.55, P < 0.05) for plain radiographs, 0.82 (range, 0.73–0.87, P < 0.05) for CT, and 0.32 (range, 0.21–0.40, P < 0.05) for MRI. When all radiographic studies were taken into consideration, paired interobserver reliability had a mean Kappa statistic of 0.70 (range, 0.55–0.85, P < 0.05). Conclusion. Our results indicate that CT most closely agrees with intraoperative findings. We therefore recommend that CT be used in any study that relies on fusion status assessment. It is important to remember, however, that even CT is not 100% accurate.

Pseudarthrosis in multilevel anterior cervical fusion with rhBMP-2 and allograft: analysis of one hundred twenty-seven cases with minimum two-year follow-up.

Study Design. Consecutive case series. Objective. The purpose of this study was to analyze the pseudarthrosis rate in a large series of recombinant human bone morphogenetic protein-2 (rhBMP-2) augmented multilevel (≥3 levels) anterior cervical fusions. Summary of Background Data. The reported pseudarthrosis rate following anterior cervical fusion varies from 0% to 20% for single-level and up to 50% for multilevel fusions. It has been postulated that the use of rhBMP-2 may decrease the pseudarthrosis rate. Methods. A consecutive series of patients with cervical spondylosis and/or disc herniation who underwent anterior cervical fusion with rhBMP-2, structural allograft, and plate fixation with a minimum 2-year follow-up were analyzed by experienced, independent spine surgeons. Results. A total of 127 patients (54 men and 73 women with mean age of 54 ± 10 years [range, 32–79]) were examined. Seventy-five (59.1%) patients underwent a 3-level fusion, 34 (26.7%) underwent a 4-level fusion, and 18 (14.2%) underwent a 5-level fusion. Of the 451 fusion segments, 14 segments (3.1%) in 13 of 127 patients (10.2%) had evidence of pseudarthrosis at 6 months following surgery. Of the 13 patients with a pseudarthrosis, 3 had a 3-level fusion (3/75 patients [4.0%]), 6 had a 4-level fusion (6/34 patients [17.4%]), and 4 had a 5-level fusion (4/18 patients [22.2%]). Five patients were asymptomatic and were not revised, but the remaining 8 patients required additional surgery. In 12 of 13 patients with a pseudarthrosis, the nonunion occurred at the lowest fusion level and at the cervicothoracic junction. The only statistically significant risk factor for developing a pseudarthrosis was the number of fusion levels. Conclusion. In a large series of rhBMP-2 augmented multilevel fusions, the pseudarthrosis rate was 10.2% at 6 months following surgery. Since the risk of pseudarthrosis increases with the number of fusion levels, a long fusion lever arm may biomechanically overwhelm the biologic advantage of rhBMP-2. While rhBMP-2 is known to enhance fusion rates, it does not guarantee fusion in all situations.

The feasibility of microscope-assisted "Free-Hand" C1 lateral mass screw insertion without fluoroscopy

Study Design. Retrospective study. Objective. To determine if C1 lateral mass screws could be safely inserted without the use of fluoroscopy. Summary of Background Data. Standard surgical technique for C1 lateral mass screw placement uses intraoperative fluoroscopy. However, intraoperative fluoroscopy is time consuming, cumbersome, and exposes both the patient and surgical team to radiation. Methods. Radiographic analysis and chart review. Surgical technique was analyzed in 3 components: feasibility to complete the screw insertion without intraoperative fluoroscopic guidance; occurrence of any intraoperative, perioperative complications; and radiologic assessment of screw positions on roentgenogram. Results. Forty-six C1 lateral mass screws were inserted in 24 consecutive patients who underwent posterior cervical fusion. There were 19 female and 5 male. The mean age was 63 ± 18 years at the time of surgery. All C1 lateral mass screws were inserted unicortically using a microscope-assisted “free-hand” technique. The average intraoperative blood loss in C1–C2 fusion was 123 ± 50 mL. The mean operative time for each C1–C2 fusion was 133 ± 30 minutes. Satisfactory positions of C1 screws were noted in intraoperative and postoperative radiograph examinations. There was no mortality or wound infection. There was no cortical breach along the screw path palpated intraoperatively. No vertebral artery injury or cerebral spinal fluid leakage during the screw insertion was observed. However, one patient with a prior posterior cervical operation had a dural tear during the exposure, another had new occipital neuralgia, and a third patient had a symptomatic occipitocervical joint violation by a C1 screw, which was diagnosed only on computed tomography scans. The symptoms resolved after the C1 screws were removed. Conclusions. Microscope-assisted “free-hand” C1 lateral mass screws insertion is a feasible and reproducible technique. which offers an alternative method of screw insertion without cumbersome and potentially harmful fluoroscopy.

Effect of fibrin sealant on drain output and duration of hospitalization after multilevel anterior cervical fusion: a retrospective matched pair analysis.

Study Design. Retrospective matched pair analysis. Objective. To determine if fibrin sealant can decrease postoperative drain output and length of stay (LOS) after multilevel anterior cervical fusions. Summary of Background Data. Despite careful hemostasis, bleeding after anterior cervical fusion can occur and may be life threatening. Although fibrin sealants are commonly used for hemostasis, no studies have been published on the efficacy of these products in achieving hemostasis after anterior cervical surgery. Methods. A retrospective age-, gender-, and fusion level-matched pair analysis was performed on 30 pairs of patients who underwent anterior cervical fusion ≥ 3 levels. In the study group, after adequate hemostasis was obtained, before wound closure 2.0 mL of fibrin sealant was applied as a fine aerosolized spray over and around the plate/fusion sites and the soft tissues to seal the main operative field. A deep drain was used in all patients. Total drain output, time for the drainage to decrease to ≤20 mL per 8 hours shift, LOS, and number of readmissions were determined and analyzed by experienced and independent spine surgeons. Results. Total drain output averaged 47 mL in the study group and 98 mL in the control group (P < 0.0001). Time for the drainage to decrease to ≤20 mL per shift averaged 17 hours (range, 8–29 hours) in the study group and 24 hours (range, 7–43 hours) in the control group (P = 0.0054). LOS averaged 1.2 days (range, 1–4 days) in the study group and 2.1 day (range, 1–5 days) in the control group (P < 0.0001). Two patients were readmitted within 4 days of discharge in each group because of swallowing difficulty, dyspnea, or pneumonia (P = 1.000). There were no adverse reactions attributable to the fibrin sealant. Conclusion. Application of fibrin sealant at the end of multilevel anterior cervical fusion can significantly decrease postoperative drain output and LOS.

Traumatic Spondylolisthesis of the Lumbar Spine: A Report of Three Cases

Traumatic spondylolisthesis of the lumbar spine is uncommon and can result in canal narrowing and spinal cord injury. Early decompression promotes recovery of neurological function. We report 3 such cases: one in the lumbosacral joint and 2 in the lumbar spine. The former patient had an open fracture-dislocation and underwent (delayed) posterior decompression and instrumentation without interbody fusion. The connecting rods broke at 3 years and the patient had a residual neurological deficit. We recommend early decompression with posterior instrumentation and interbody fusion for maximum recovery of neurological function and stability of the spine.

Revision Surgery Following Cervical Laminoplasty Etiology and Treatment Strategies

Study Design. Retrospective review of prospectively collected data. Objective. To identify the cause of failed open-door laminoplasty and to describe the surgical strategies for revision surgery. Summary of Background Data. Although laminoplasty has become popular, few articles have addressed the cause of failed cervical laminoplasty requiring revision surgery. Methods. All patients who required revision surgery following open-door cervical laminoplasty were identified. Clinical data, method of surgical revision, time between surgeries, Nurick grade, radiologic parameters, and complications were analyzed. Laminoplasty failures were classified into 3 categories: “technique related,” “inadequate symptomatic relief after treatment,” or “recurrence of symptoms due to disease progression.” Results. A total of 130 patients underwent cervical laminoplasty over a 10-year period (1996–2006), and 12 patients (9.2%) required revision surgery. The mean age was 50.7 years at the time of the index laminoplasty (range, 34–67 years) and 51.8 years (range, 35–70 years) at the time of the revision surgery. Mean duration of symptoms was 7.3 months before the index procedure (range, 2–17 months) and 5.6 months (range, 1–14 months) before revision surgery. The mean time interval between the index procedure and revision surgery was 16.6 months (range, 4–43 months). Of the 12 patients who required revision surgery, 5 had global lordosis of <10°, 4 developed local kyphosis >13°, and 5 had increased degenerative spondylolisthesis. Nonmyelopathic causes resulted in 50% of the revision surgery. Of 12 patients, 3 (25%) required revision surgery due to technique-related factors; 1 (8%) required surgery due to inadequate symptomatic relief after treatment; and 8 (67%) required revision surgery due to disease progression. Conclusion. Of the 130 patients who underwent cervical laminoplasty over a 10-year period, 12 patients (9.2%) required revision surgery. Although laminoplasty is generally successful, failures due to disease progression, technique-related factors, and inadequate symptomatic relief after treatment can occur. Patients should, therefore, be counseled regarding the potential need for revision surgery when undergoing open-door laminoplasty.

Metastatic Spine Tumor Surgery: A Comparative Study of Minimally Invasive Approach Using Percutaneous Pedicle Screws Fixation Versus Open Approach.

Study Design: Prospective cohort study. Summary of Background Data: Minimally invasive spinal surgery (MISS) has been gaining recognition in patients with metastatic spine disease (MSD). The advantages are reduction in blood loss, hospital stay, and postoperative morbidity. Most of the studies were case series with very few comparing the outcomes of MISS to open approaches. Objective: To evaluate and compare the clinical and perioperative outcomes of MISS versus open approach in patients with symptomatic MSD, who underwent posterior spinal stabilization and/or decompression. Patients and Methods: Our study included 45 MSD patients; 27 managed by MISS and 18 by open approach. All patients had MSD presenting with symptoms of neurological deficit, spinal instability, or both. Preoperative, intraoperative, and postoperative data were collected for comparison of the 2 approaches. All patients were followed up until the end of study period (maximum up to 4 years from time of surgery) or till their demise. The clinical outcome measures were pain control, neurological and functional status, whereas perioperative outcomes were blood loss, operative time, length of hospital stay, and time taken to initiate radiotherapy/chemotherapy after index surgery. Results: Majority of patients in both groups showed improvement in pain, neurological status, independent ambulation, and ECOG score in the postoperative period with no significant differences between the 2 groups. There was a significant reduction in intraoperative blood loss (621 mL less, P<0.001) in the MISS group. The average time to initiate radiotherapy after surgery was 13 days (range, 12–16 d) in MISS and 24 days (range, 16–40 d) in the open group. This difference was statistically significant (P<0.001). Operative time and duration of hospital stay were also favorable in the MISS group, although the differences were not significant. Conclusions: MISS is comparable with open approach demonstrating similar improvements in clinical outcomes, that is pain control, neurological and functional status. MISS approaches have also shown promising results due to lesser intraoperative blood loss and allowing earlier radiotherapy/chemotherapy.

Adding-on Phenomenon After Surgery in Lenke Type 1, 2 Adolescent Idiopathic Scoliosis: Is it Predictable?

Study Design. A retrospective study. Objective. The aim of this study was to detect risk factors for Adding-on after posterior correction surgery in patients with Lenke 1 or 2 AIS, and to explore whether Adding-on Index could be used to predict Adding-on effectively. Summary of Background Data. Adding-on phenomenon is a common complication in Lenke 1 or 2 AIS patients after correction surgery. However, whether it can be predicted after surgery remains unknown. Methods.. Lenke 1 or 2 AIS patients receiving correction surgery in our center from January 2009 to July 2013 were analyzed. Antero-posterior and lateral films were evaluated before surgery, at 2 weeks’ and 2 years’ follow-up. Patients were divided into 2 groups according to whether Adding-on occurred at the 2 years’ follow-up. Risk factors of Adding-on were analyzed, and Adding-on Index was proposed and verified. Results. Sixteen patients (16.3%) suffered from distal Adding-on at 2-year follow-up. Several parameters were found to be significantly different between 2 groups, including Rissers sign, postoperative Cobb angle of main thoracic, postoperative Cobb angle of main thoracic curve at 2-year follow-up, preoperative and postoperative Cobb angle of lumbar curve, postoperative Cobb angle of lumbar curve at 2-year follow-up, LIV-EV, LIV-SV, LIV-CSVL, LAV-CSVL, LAV-LIV, DnfS, and postoperative TJK. No significant differences in SRS-22 scores were observed. Binary logistic regression analysis showed that DnfS and postoperative residual Cobb angle of lumbar curve were primary factors for occurrence of Adding-on. According to the regression equation, Adding-on Index was defined as 4 × DnfS-postoperative lumbar curves Cobb angle. On the basis of ROC curve, if Adding-on Index was more than 12, the occurrence rate of Adding-on was 88%. On the contrary, the rate of no Adding-on phenomenon was 80%. Conclusion. DnfS and posterior Cobb angle of lumbar curve were 2 important factors for Adding-on in Lenke 1, 2 AIS patients. Adding-on Index can be used to predict the occurrence of Adding-on effectively. Level of Evidence: 4

Cervical Alignment Variations in Different Postures and Predictors of Normal Cervical Kyphosis - A New Understanding.

Study Design. Comparative study of prospectively collected radiographic data. Objective. To predict physiological alignment of the cervical spine and study its morphology in different postures. Summary of Background Data. There is increasing evidence that normal cervical spinal alignment may vary from lordosis to neutral to kyphosis, or form S-shaped or reverse S-shaped curves. Methods. Standing, erect sitting, and natural sitting whole-spine radiographs were obtained from 26 consecutive patients without cervical spine pathology. Sagittal vertical axis (SVA), global cervical lordosis, lower cervical alignment C4-T1, C0-C2 angle, T1 slope, C0-C7 SVA and C2-7SVA, SVA, thoracic kyphosis, thoracolumbar junctional angle, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence were measured. Statistical analysis was performed to elucidate differences in cervical alignment for all postures. Predictive values of T1 slope and SVA for cervical kyphosis were evaluated. Results. Most patients (73.0%) do not have lordotic cervical alignment (C2-C7) upon standing (mean −0.6, standard deviation 11.1°). Lordosis increases significantly when transitioning from standing to erect sitting, as well as from erect to natural sitting (mean −17.2, standard deviation 12.1°). Transition from standing to natural sitting also produces concomitant increases in SVA (−8.8–65.2 mm) and T1-slope (17.4°–30.2°). T1 slope and SVA measured during standing significantly predicts angular cervical spine alignment in the same position. SVA < 10 mm significantly predicts C4-C7 kyphosis (P < 0.001), and to a lesser extent, C2-C7 kyphosis (P = 0.02). T1 slope <20° is both predictive of C2-C7 and C4-7 kyphosis (P = 0.001 and P = 0.023, respectively). For global cervical Cobb angle, T1 slope seems to be a more significant predictor of kyphosis than SVA (odds ratio 17.33, P = 0.001 vs odds ratio 11.67, P = 0.02, respectively). Conclusion. The cervical spine has variable normal morphology. Key determinants of its alignment include SVA and T1 slope. Lordotic correction of the cervical spine is not always physiological and thus correction targets should be individualized. Level of Evidence: 3

Spontaneous spinal epidural haematoma after antiplatelet treatment: a report of two cases.

We report 2 cases of spontaneous spinal epidural haematoma after antiplatelet treatment. One patient was on ticlodipine therapy and the other was on aspirin and clopidogrel. Both diagnoses were made using magnetic resonance imaging. One patient underwent multilevel laminectomies and posterior spinal fusion within 24 hours of symptom onset and achieved complete neurological recovery. The other underwent unilateral hemilaminectomies 40 hours after symptom onset and did not show neurological improvement. A high index of suspicion is needed for patients presenting with severe lower back pain and rapid neurological deterioration, especially in those on antiplatelet therapy. Urgent spinal cord decompression and epidural haematoma cord evacuation may provide more favourable outcome.