Preoperative patient-reported outcome score thresholds predict the likelihood of reaching MCID with surgical correction of adult spinal deformity.

BACKGROUND CONTEXT: Preoperative (pre-op) identification of patients likely to achieve a clinically meaningful improvement following surgery for adult spinal deformity (ASD) is critical, especially given the substantial cost and comorbidity associated with surgery. Even though pain is a known indication for surgical ASD correction, we are not aware of established thresholds for baseline pain and function to guide which patients have a higher likelihood of improvement with corrective surgery. PURPOSE: We aimed to establish pre-op patient-reported outcome measure (PROM) thresholds to identify patients likely to improve by at least one minimum clinically important difference (MCID) with surgery for ASD. STUDY DESIGN: This is a retrospective cohort study using prospectively collected data. PATIENT SAMPLE: We reviewed 172 adult patients' charts who underwent corrective surgery for spinal deformity. OUTCOME MEASURES: Included measures were the Visual Analog Scale for pain (VAS), Oswestry Disability Index (ODI), and Scoliosis Research Society-22 (SRS-22). Our primary outcome of interest was improvement by at least one MCID on the ODI and SRS-22 at 2 years after surgery. METHODS: As part of usual care, the VAS, ODI, and SRS-22 were collected pre-op and re-administered at 1, 2, and 5 years after surgery. MCIDs were calculated using a distribution-based method. Determining significant predictors of MCID at two years was accomplished by Firth bias corrected logistic regression models. Significance of predictors was determined by Profile Likelihood Chi-square. We performed a Youden analysis to determine thresholds for the strongest pre-op predictors. RESULTS: At year two, 118 patients (83%) reached MCID for the SRS and 127 (75%) for the ODI. Lower pre-op SRS overall, lower pre-op SRS pain, and higher pre-op SRS function predicted a higher likelihood of reaching MCID on the overall SRS (p < 0.05). Higher pre-op ODI, lower SRS pain and self-image, and higher SRS overall predicted a higher likelihood of reaching MCID on the ODI (p < 0.05). An ODI threshold of 29 predicted reaching MCID with a sensitivity of 0.89 and a specificity of 0.64 (AUC = 0.7813). An SRS threshold of 3.89 predicted reaching MCID with a sensitivity of 0.93 and specificity of 0.68 (AUC = 0.8024). CONCLUSIONS: We identified useful thresholds for ODI and SRS-22 with acceptable predictive ability for improvement with surgery for ASD. Pre-op ODI, SRS, and multiple SRS subscores are predictive of meaningful improvement on the ODI and/or SRS at 2 years following corrective surgery for spinal deformity. These results highlight the usefulness of PROMs in pre-op shared decision-making.

Relationship Between Preoperative Plasma Fibrinogen Concentration, Perioperative Bleeding, and Transfusions in Elective Adult Spinal Deformity Correction.

STUDY DESIGN: Retrospective analysis. OBJECTIVE: This study sought to investigate the relationship between preoperative (preop) fibrinogen, bleeding, and transfusion requirements in adult spinal deformity corrections. SUMMARY OF BACKGROUND DATA: Blood loss after major spinal reconstruction increases the risks and costs of surgery. Preoperative fibrinogen levels may predict intra- and postoperative blood loss. METHODS: Data were collected from clinic charts and hospital medical records of all 142 of a single surgeon's consecutive adult spine patients undergoing 7 or more levels deformity correction surgeries from January 2011 to December 2014. t tests were used to compare perioperative variables between patients with total blood loss in the upper quartile (≥1,000 mL) and the remaining patients. Similarly, patients receiving >2 units of packed red cells (PRCs) were compared with others. Analysis of variance was used to compare the blood loss between the patients' groups (quartiles) based on their preoperative fibrinogen concentration. RESULTS: Mean total blood loss was 847.9 (±543.6) mL. Overall, mean preoperative fibrinogen concentration was 254.8 (±82.9) mg/dL. Patients with lower fibrinogen concentration (<193 mg/dL) experienced significantly higher blood loss than those with higher concentrations (p < .05). Patients with transfusion >2 units PRC had significantly greater number of spinal levels treated, higher mean operative time, total blood loss and lower mean preoperative fibrinogen than those transfused 2 or fewer units PRC (p < .05). Total blood loss correlated significantly with preoperative fibrinogen concentration (r = -0.51, p < .05). All the thromboelastography (TEG) variables (G, K, and Angle) correlated significantly with preoperative fibrinogen (p < .05). CONCLUSIONS: In our cohort undergoing correction of adult spinal deformity, patients with preoperative fibrinogen level lower than 193 mg/dL had significantly higher bleeding than their counterparts. Perioperative transfusion requirements correlated moderately both with the blood loss and preoperative fibrinogen concentration. Incorporation of preoperative fibrinogen allows better prediction of total perioperative blood loss and may therefore guide the treatment team in use of ameliorating therapies. LEVEL OF EVIDENCE: Level IV.

Should long-segment cervical fusions be routinely carried into the thoracic spine? A multicenter analysis.

BACKGROUND CONTEXT: Although recommendations for caudal "end level" in posterior cervical reconstruction remain highly variable, the benefits of routine extension of posterior cervical fusions into the thoracic spine remain unclear. PURPOSE: We compared clinical and radiographic outcomes in patients in whom posterior fusions ended in the cervical spine versus those in whom the fusion was extended into the thoracic spine. STUDY DESIGN/SETTING: A multicenter retrospective analysis of prospectively followed patients was carried out. PATIENT SAMPLE: A total of 177 adult spine patients undergoing three or more levels of posterior cervical fusions for degenerative disease from January 2008 to May 2013 comprised the patient sample. OUTCOME MEASURES: Cervical lordosis, C2-C7 sagittal plumbline, T1 slope, visual analog scale (VAS), Oswestry Disability Index (ODI), rate of pseudarthrosis, length of hospital stay (LOS), estimated blood loss (EBL), and operating room [OR] time were the outcome measures. METHODS: We assembled a multicenter (four sites) radiographic and clinical database of patients who had undergone three or more levels of posterior cervical fusions for degenerative disease from January 2008 to May 2013 with at least 2 years of postoperative (post-op) follow-ups. Patients were divided into two groups: Group 1 (fusion ending in the cervical spine) and group 2 (fusion extending into the thoracic spine). All radiographic measurements were performed by an independent experienced clinical researcher. RESULTS: Group 1 and Group 2 had 104 and 73 patients, respectively. Mean EBL for Group 2 was significantly higher than Group 1. Mean OR time and LOS were comparatively higher for Group 2 than Group 1 but were not statistically significant (p>.05). Mean cervical lordosis improved postoperatively in both groups. There were no statistically significant differences in change or maintenance of mean cervical lordosis (2 weeks vs. 2 years post-op) between the two groups (p>.05). Similarly, the change in mean C2-C7 sagittal plumbline and T1 slope was not statistically significantly different between the two groups or with follow-up(p>.05). Clinically, significant improvements in VAS and ODI were noted in both groups from preop to final follow-up, but the difference between groups was not statistically significant. Although the rate of pseudarthrosis was significantly higher in Group 1 (21.2%) than in Group 2 (10.96%), there were no statistically significant differences in adjacent segment degeneration or revision surgery rates between the groups. CONCLUSION: Both groups had similar clinical and radiographic outcomes. Extension of a posterior cervical fusion into the thoracic spine leads to lower pseudarthrosis rate, whereas stopping in the cervical spine yields lower EBL, OR time, and LOS, demonstrating that there are different benefits for each approach. However, although the optimal end-level remains debatable, there are scenarios in which upper thoracic extension should be considered. At this point, we recommend extension of surgery in smokers and other patients at increased risk for pseudarthrosis as well as in patients with anatomical limitations to strong C7 bone anchorage.

Is Preoperative Fibrinogen Testing Associated With Total Blood Loss in Adolescent Idiopathic Scoliosis Correction?

STUDY DESIGN: Retrospective analysis. OBJECTIVE: This study sought to investigate the potential association between preoperative fibrinogen, bleeding, and transfusion requirements in adolescent idiopathic scoliosis (AIS) corrections. SUMMARY OF BACKGROUND DATA: Blood loss after major spinal reconstruction increases the risks and costs of surgery. Preoperative fibrinogen levels may predict intra- and postoperative blood loss. METHODS: Data were collected from clinic charts and hospital medical records of all 110 of a single surgeon's consecutive AIS patients undergoing greater than three-level deformity correction surgeries from January 2011 to December 2013. Pearson test was used to investigate the correlation between bleeding and clinical variables, with level of significance set at α = 0.05. RESULTS: Mean total bleeding volume was 488 (±356) mL. Overall, mean preoperative fibrinogen concentration was 188.6 ± 32.8 mg/dL. Preoperative platelet counts, prothrombin time (PT), and activated partial thromboplastin time (aPTT) did not correlate significantly with preoperative fibrinogen concentration (p > .05). Both packed red cells (PRC) and packed red blood cells (PRBC) correlated significantly with preoperative fibrinogen (p < .05). The correlation between PRC and preoperative fibrinogen was -0.042. There was a negative correlation between PRBC and preoperative fibrinogen (r = -0.46). Overall mean thromboelastography (TEG) values were within normal range in both males and females and both had comparable TEG parameter values. All the TEG variables (G, K, and Angle) correlated significantly with preoperative fibrinogen (p < .05) but not with total blood volume (p > .05). The correlation coefficient between these TEG variables and preoperative fibrinogen were 0.51, 0.59, and 0.54, respectively. The total bleeding volume and % estimated blood volume correlated significantly with both PRC (r = 0.352, r = 0.376; p < .05) and PRBC (r = 0.621, r = 0.614; p < .05). CONCLUSIONS: In our cohort undergoing correction of AIS, preoperative fibrinogen levels exhibited a significant negative logarithmic correlation with total blood loss. TEG variables also correlated significantly with preoperative fibrinogen levels. Efforts should be made to incorporate this measure in perioperative blood management program for AIS corrections. LEVEL OF EVIDENCE: Level IV.

Lumbar Microdiscectomy.

In most patients, the radiculopathy associated with lumbar disc herniation resolves nonoperatively. For patients in whom nonsurgical management has failed, microdiscectomy can be considered. Today, an operating microscope is preferred because of the collinear light and magnification offered. Alternatively, loupes and a headlight may be employed. The major steps of the procedure are (1) making a 2-cm vertical incision and then developing the corridor to the lamina subperiosteally or by using serial dilation techniques; (2) confirming the level of surgery radiographically prior to incision and once the lamina has been reached and then detaching the lateral attachments of the flavum; (3) making a small laminotomy, resecting any superior facet osteophytes, then mobilizing the compressed traversing nerve root, and, in some cases, making a small annulotomy; and (4) removing loose disc fragments and performing wound closure. Most outcomes reports after microdiscectomy have been favorable for radicular symptoms. Associated back pain typically decreased as well. Common complications include recurrent disc herniation or disc herniation at another level, wound infections, and durotomy with spinal headache.

Feasibility of rigid upper cervical instrumentation in children: tomographic analysis of children aged 2-6.

STUDY DESIGN: Tomographic analysis of occipitocervical (OC) instability in children aged between 2 and 6 years. OBJECTIVE: To assess the feasibility of screw placement in various bone anchors in the OC region in young children. SUMMARY OF BACKGROUND DATA: The use of rigid stabilization in the pediatric patients is gradually increasing. No study has comprehensively assessed the suitability of bony anatomy of the OC region for screw placement, especially in younger children. METHODS: A total of 50 patients (2-6 y, 10 each) who underwent skull and cervical CT scanning were randomly queried using an x-ray database. Screw placement was considered feasible if there was at least 0.5 mm of bone around a 3.5 mm screw through its trajectory. When the bony channel measured 3.5-4.0 mm, placement was considered possible, but difficult. RESULTS: Statistically, most measures were similar from the right to left sides. External occipital protuberance thickness increased from a mean value of 8.60 mm to a mean value of 10.73 mm. The mean C1 lateral mass length and width varied from 15.26 to 16.67 mm (P=0.056) and 7.34 to 8.58 mm (P=0.0005), respectively, with age. The mean C2 pedicle width and length varied from 3.85 to 4.18 and 17.11 to 19.8 mm, respectively, with age. The mean C2 laminar screw length increased from 20.4 to 22.66 mm with age (P<0.001). C2 lamina widths did not vary much by age. The mean C1-C2 transarticular path length and height increased from 26.7 to 33.6 mm and 2.58 to 3.09 mm, respectively, with age. The width was less directly variable by age (2.68-3.09 mm). CONCLUSIONS: Standard 3.5 mm screws can be used for OC and upper cervical instabilities in children aged between 2 and 6 years. Some anchor points appeared safer compared with others. The occipital keel, C1 lateral mass, and C2 laminae offered adequate space for screw placement in almost all cases. C2 pedicles offered adequate space in 49 sides and barely adequate space in 25 pedicles. Transarticular screws could be safely placed in only 4 of 100 sides. Close radiographic assessment of the vertebral artery course and bony architecture are recommended before surgery in pediatric patients with OC and upper cervical instability.

Cervical total disc replacement with the Mobi-C cervical artificial disc compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled multicenter clinical trial: clinical article.

OBJECT: Cervical total disc replacement (TDR) is intended to treat neurological symptoms and neck pain associated with degeneration of intervertebral discs in the cervical spine. Anterior cervical discectomy and fusion (ACDF) has been the standard treatment for these indications since the procedure was first developed in the 1950s. While TDR has been shown to be a safe and effective alternative to ACDF for treatment of patients with degenerative disc disease (DDD) at a single level of the cervical spine, few studies have focused on the safety and efficacy of TDR for treatment of 2 levels of the cervical spine. The primary objective of this study was to rigorously compare the Mobi-C cervical artificial disc to ACDF for treatment of cervical DDD at 2 contiguous levels of the cervical spine. METHODS: This study was a prospective, randomized, US FDA investigational device exemption pivotal trial of the Mobi-C cervical artificial disc conducted at 24 centers in the US. The primary clinical outcome was a composite measure of study success at 24 months. The comparative control treatment was ACDF using allograft bone and an anterior plate. A total of 330 patients were enrolled, randomized, and received study surgery. All patients were diagnosed with intractable symptomatic cervical DDD at 2 contiguous levels of the cervical spine between C-3 and C-7. Patients were randomized in a 2:1 ratio (TDR patients to ACDF patients). RESULTS: A total of 225 patients received the Mobi-C TDR device and 105 patients received ACDF. At 24 months only 3.0% of patients were lost to follow-up. On average, patients in both groups showed significant improvements in Neck Disability Index (NDI) score, visual analog scale (VAS) neck pain score, and VAS arm pain score from preoperative baseline to each time point. However, the TDR patients experienced significantly greater improvement than ACDF patients in NDI score at all time points and significantly greater improvement in VAS neck pain score at 6 weeks, and at 3, 6, and 12 months postoperatively. On average, patients in the TDR group also maintained preoperative segmental range of motion at both treated segments immediately postoperatively and throughout the study period of 24 months. The reoperation rate was significantly higher in the ACDF group at 11.4% compared with 3.1% for the TDR group. Furthermore, at 24 months TDR demonstrated statistical superiority over ACDF based on overall study success rates. CONCLUSIONS: The results of this study represent the first available Level I clinical evidence in support of cervical arthroplasty at 2 contiguous levels of the cervical spine using the Mobi-C cervical artificial disc. These results continue to support the use of cervical arthroplasty in general, but specifically demonstrate the advantages of 2-level arthroplasty over 2-level ACDF. Clinical trial registration no.: NCT00389597 (ClinicalTrials.gov).

Cervical stenosis in adults undergoing thoracolumbar deformity surgery: incidence, treatment, and complications: clinical article.

OBJECT: The goals of this study were to determine the incidence of occult cervical stenosis in patients over 50 years old with thoracolumbar deformity and to assess the risk of progressive cervical myelopathy after complex thoracolumbar reconstruction in asymptomatic or mildly symptomatic patients with cervical stenosis. METHODS: Charts and cervical imaging for patients who were over 50 years old when they had undergone thoracolumbar deformity surgery between 2005 and 2008 were reviewed. Patients with primary neurological disorders were excluded from the study. RESULTS: Seventy-three patients (56 women and 17 men) met the study inclusion criteria. The minimum follow-up time was 2 years. Fifty-eight percent of patients (42 of 73) had cervical stenosis on advanced imaging. Thirty-three patients had mild or moderate stenosis; only 3 of these patients had clinical myelopathy. Nine patients (12%) had critical cervical stenosis, as determined from imaging; among these patients, 3 had moderate or severe myelopathy. Patients with noncritical stenosis and no or mild myelopathy underwent thoracolumbar reconstruction without any postoperative progression of myelopathy. Patients with critical stenosis and/or moderate or severe myelopathy were offered cervical decompression prior to thoracolumbar reconstruction; those who accepted this offer did not have progression of myelopathy. One patient underwent thoracolumbar reconstruction first despite critical cervical stenosis. At 20 months, her cervical myelopathy had progressed, and she ultimately required cervical decompression. CONCLUSIONS: Cervical stenosis, even critical stenosis in some cases, was seen in more than one-half of the patients. Most presented without obvious cervical complaints. In those with mild to moderate stenosis and no or mild myelopathy, lengthy thoracolumbar reconstruction procedures were not associated with progression of the myelopathy. The authors recommend that all adults with thoracolumbar deformity undergo a detailed upper- and lower-extremity neurological examination prior to major thoracolumbar reconstruction.

Image-guided thoracoscopic spinal surgery: a merging of 2 technologies.

STUDY DESIGN: Retrospective clinical and intraoperative navigational data review. OBJECTIVE: To evaluate quantitatively the application of frameless stereotactic image guidance in thoracoscopic discectomy procedures. SUMMARY OF BACKGROUND DATA: Thoracoscopic spinal surgery has technical and anatomic challenges that result in difficult orientation with a 2-dimensional imaging procedure in a complex 3-dimensional structure. METHODS: There were 16 patients who underwent image-guided thoracoscopic discectomy procedures that combine these 2 technologies. Accuracy was determined by the registration (calculated) error and actual navigation (intraoperative) error. The clinical outcomes and complications were reviewed. RESULTS: Accuracy determined by registration (calculated) and navigation (intraoperative) was 1.7 and 1.2 mm, respectively. The additional time required for the image guidance portion of the procedure was countered by the efficiency of the remaining procedure. Clinical outcomes and complication were comparable with previous experience. CONCLUSIONS: Image-guided thoracoscopic spinal surgery can provide 3-dimensional orientation to a 2-dimensional imaging procedure that ultimately improves accuracy, efficiency, and safety. Future developments in combining guidance technology with standard surgical procedures will likely continue.

Paraparesis in a black man brought on by ossification of the ligamentum flavum: case report and review of the literature.

We present the second case of paraparesis secondary to ossification of the ligamentum flavum at the midthoracic region in a black man. Ossification of the ligamentum flavum is frequently described in the Japanese population where the presentation is often in the lower thoracic region. The patient is a 37-year-old black man who, over the 6 months before admission, noticed progressive paraparesis. CT myelogram revealed severe thoracic stenosis by an ossified ligamentum flavum from T4 to T7 with most severe involvement at the T5, T6, and T7 levels. The patient underwent multilevel laminectomies and medial facetectomies from T4 to T7. Over the past decade, ossification of the ligamentum flavum has been reported with increasing frequency in non-Asian patients. This is the third case report in a black man. In addition, ossification of the ligamentum flavum in this particular location is rarely reported. The increased use of advanced neuroimaging techniques in the evaluation of "back pain" may reveal that the prevalence of this condition is higher than expected in non-Asian populations. Improvement in neurologic symptoms secondary to decompressive laminectomies will depend on the degree and duration of spinal cord compression.

Spinal neurocysticercosis.

Worldwide, cysticercosis is the most common parasitic infection of the central nervous system. In endemic regions, the incidence of neurocysticercosis (NCC) approaches 4% of the general population. The disease is predominantly intracranial, the authors of most series generally report the incidence of spinal NCC as only 1.5 to 3% of all cases. Although spinal NCC is relatively rare, it represents a distinct clinical entity that can have devastating consequences for the patient. Because of the limited size of the spinal canal, the mass effect of these lesions is poorly tolerated. Most spinal NCC occurs in the subarachnoid space where mass effect can cause spinal cord compression, although obstruction of cerebrospinal fluid pathways due to scarring of the subarachnoid space can also cause symptoms. The authors treated six patients with spinal NCC. In five cases the lesions were located in the subarachnoid space, and in one the lesion was intramedullary. All patients with subarachnoid spinal NCC required excision of the symptomatic lesions; in two cases initial medical therapy had failed. The patient with intramedullary spinal NCC experienced mild symptoms and underwent steroid therapy. All patients experienced variably improved outcomes and were eventually ambulatory. Medical therapy should be carefully considered in selected patients in whom symptoms are stable and nonprogressive. Surgical intervention is required when severe or progressive deficits occur to prevent permanent injury. In some patients recovery may be limited as a result of inflammatory injury to the spinal cord or arachnoidal adhesions.

Posterior atlantoaxial stabilization: new alternative to C1-2 transarticular screws.

OBJECT: Surgical treatment of atlantoaxial instability has evolved to include various posterior wiring techniques including Brooks, Gallie, and Sonntag fusions in which success rates range from 60 to 100%. The Magerl-Seemans technique in which C1-2 transarticular screws are placed results in fusion rates between 87 and 100%. This procedure is technically demanding and requires precise knowledge of the course of the vertebral arteries (VAs). The authors introduce a new C1-2 fixation procedure in which C-1 lateral mass and C-2 pedicle screws are placed that may have advantages over C1-2 transarticular screw constructs. METHODS: A standard posterior C1-2 exposure is obtained. Polyaxial C-2 pedicle screws and C-1 lateral mass screws are placed bilaterally. Rods are connected to the screws and secured using locking nuts. A cross-link is then placed. Fusion can be performed at the atlantoaxial joint by elevating the C-2 nerve root. The technique for this procedure has been used in four cases of atlantoaxial instability at the author's institution. There have been no C-2 nerve root- or VA-related injuries. No cases of construct failure have been observed in the short-term follow up period. CONCLUSIONS: Atlantoaxial lateral mass and axial pedicle screw fixation offers an alternative means of achieving atlantoaxial fusion. The technique is less demanding than that required for transarticular screw placement and may avoid the potential complication of VA injury. The cross-linked construct is theoretically stable in flexion, extension, and rotation. Laminectomy or fracture of the posterior elements does not preclude use of this fixation procedure.