Faculty Bibliography

BACKGROUND:Intraoperative neuromonitoring (ION) such as motor-evoked potential (MEP), somatosensory evoked potentials (SSEP) and electromyography (EMG) are used to detect impending neurological injuries during spinal surgery. To date, little is known on the trends in the use of ION for scoliosis surgery in the United States. METHODS:A retrospective review was performed using the PearlDiver Database to identify patients that had scoliosis surgery with and without ION from years 2005 to 2011. Demographic information (such as age, gender, region within the United States) and clinical information (such as type of ION and rates of neurological injury) were assessed. RESULTS:There were 3618 patients who had scoliosis surgery during the study period. ION was used in 1361 (37.6%) of these cases. The number of cases in which ION was used increased from 27% in 2005 to 46.9% in 2011 (p < 0.0001). Multimodal ION was used more commonly than unimodal ION (64.6% vs. 35.4%). The most commonly used modality was combined SSEP and EMG while the least used modality was MEP only. Neurological injuries occurred in 1.8% and 2.0% of patients that had surgery with and without ION, respectively (p = 0.561). ION was used most commonly in patients < 65 years of age and in the Northeastern part of the United States (age; p = 0.006, region; p < 0.0001). CONCLUSIONS:The use of ION for scoliosis surgery gradually increased annually from 2005 to 2011. Age and regional differences were noted with neuromonitoring being most commonly used for scoliosis surgery in non-elderly patients and in the Northeastern part of the United States. No differences were noted in the risk of neurological injury in patients that had surgery with and without ION. Although the findings from this study may seem to suggest that ION may not influence the risk of neurologic injury, this result must be interpreted with caution as inherently riskier surgeries may utilize ION more, leading to an actual reduction in injuries more dramatic than observed in this study.

BACKGROUND CONTEXT:Minimally invasive sacroiliac (SI) joint fusion has become increasingly relevant in recent years as a treatment for SI joint pathology. Previous studies have found minimally invasive SI fusion to be an effective and safe treatment option for chronic SI joint pain. However, these studies have been primarily single-center, case-based, or manufacturer-sponsored investigations, and as such their findings are limited to their sample populations. PURPOSE:The aim of this study was to investigate the safety of minimally invasive SI fusion using a large nationwide sample group to more accurately identify complication rates of this increasingly popular procedure. STUDY DESIGN/SETTING:This is a retrospective database study. PATIENT SAMPLE:The sample includes patients within the orthopedic subset of Humana database who underwent minimally invasive SI fusion between 2007 and 2014. OUTCOME MEASURES:Complications and novel lumbar and nerve pathology were the outcome measures. METHODS:Patients undergoing minimally invasive SI fusion from 2007 to 2014 were identified using the Pearl Diver patient record database (Pearl Diver Technologies, West Conshohocken, PA, USA) from the nationwide private insurance provider Humana Inc. This approach provided access to records of over 18 million patients in every major geographic region of the country. Using the ICD-9 diagnosis codes (International Classification of Diseases 9th edition), data from patient records were analyzed to reveal incidence of postoperative infection, pain, osteomyelitis, joint derangement, urinary tract infection, and novel lumbar and nervous system pathology. RESULTS:Four hundred sixty-nine patients (305 female; 164 male) within the Humana insurance database received minimally invasive SI fusion between 2007 and 2014. Data from these patients showed a substantial increase in the use of the procedure over this 7-year period. Among these patients, an overall complication rate of 13.2% (n=62) was seen at 90 days postoperatively and 16.4% (n=77) at 6 months. The number of patients receiving a first time diagnosis of lumbar pathology following minimally invasive SI fusion in the sample population was also analyzed. The incidence of novel lumbar pathology in this population was 3.6% (n=17) at 90 days postoperatively and 5.3% (n=25) at 6 months. Men experienced diagnoses of novel lumbar pathology at higher rates than women within both 90 days (men=6.7%; women≤3.3%) and 6 months (men=9.1%; women≤3.3%) of the procedure (p<.01). CONCLUSIONS:The results of this study show that minimally invasive SI joint fusion could possibly carry higher risks of complications than previously stated. These findings are useful for physicians and patients when considering treatment for chronic SI joint pain.

The purpose of this review was to compare the efficacy and safety of synthetic bone graft substitutes versus autograft or allograft for the treatment of lumbar and cervical spinal degenerative diseases. Multiple major medical reference databases were searched for studies that evaluated spinal fusion using synthetic bone graft substitutes (either alone or with an autograft or allograft) compared with autograft and allograft. Randomized controlled trials (RCT) and cohort studies with more than 10 patients were included. Radiographic fusion, patient-reported outcomes, and functional outcomes were the primary outcomes of interest. The search yielded 214 citations with 27 studies that met the inclusion criteria. For the patients with lumbar spinal degenerative disease, data from 19 comparative studies were included: 3 RCTs, 12 prospective, and 4 retrospective studies. Hydroxyapatite (HA), HA+collagen, β-tricalcium phosphate (β-TCP), calcium sulfate, or polymethylmethacrylate (PMMA) were used. Overall, there were no differences between the treatment groups in terms of fusion, functional outcomes, or complications, except in 1 study that found higher rates of HA graft absorption. For the patients with cervical degenerative conditions, data from 8 comparative studies were included: 4 RCTs and 4 cohort studies (1 prospective and 3 retrospective studies). Synthetic grafts included HA, β-TCP/HA, PMMA, and biocompatible osteoconductive polymer (BOP). The PMMA and BOP grafts led to lower fusion rates, and PMMA, HA, and BOP had greater risks of graft fragmentation, settling, and instrumentation problems compared with iliac crest bone graft. The overall quality of evidence evaluating the potential use and superiority of the synthetic biological materials for lumbar and cervical fusion in this systematic review was low or insufficient, largely due to the high potential for bias and small sample sizes. Thus, definitive conclusions or recommendations regarding the use of these synthetic materials should be made cautiously and within the context of the limitations of the evidence.

STUDY DESIGN/METHODS:Retrospective study. OBJECTIVE:Symptomatic scoliosis can be a source of severe pain and disability. When nonoperative treatments fail, spine fusion is considered as an effective procedure in scoliosis management. The purpose of this study was to evaluate the trends of patients with scoliosis undergoing posterior long segment fusion (PLSF) with and without recombinant human bone morphogenetic protein 2 (rhBMP-2). METHODS:Patients within the orthopedic subset of Medicare database undergoing PLSF from 2005 to 2011 were identified using the PearlDiver Patient Records Database. Both diagnosis and procedural International Classification of Diseases, ninth edition and Current Procedural Terminology codes were used. The year of procedure, age, sex, region, and rhBMP-2 use were recorded. RESULTS:In total, 1,265,591 patients with scoliosis were identified with 29,787 PLSF surgeries between 2005 and 2011. The incidence of PLSF procedures increased gradually from 2005 to 2009, decreased in 2010 (p < 0 0.01), and grew again in 2011. Patients over age 84 years had the highest incidence of PLSF. The lowest incidence of the procedures was in the Northeast, 5.96 per 100,000 patients. Sex differences were observed with a male-to-female ratio of 0.40 (p < 0.01). The use of rhBMP-2 for PLSF increased steadily from 2005 to 2009; the numbers dropped dramatically in 2010 and returned by 2011. CONCLUSIONS:According to our study, patients with scoliosis demonstrated a 0.6575 average incidence increase of PLSF treatments annually. There were significant differences in incidence of PLSF procedure and patient demographics. Additionally, rhBMP-2 consumption significantly changed when we stratified it by sex, age, and region respectively.

OBJECT/OBJECTIVE:The objective of this study was to compare the incidence of degeneration and need for subsequent fusion surgery between patients who were treated nonsurgically and patients treated with fusion after a diagnosis of thoracic-or lumbar-level fracture without degenerative disease. METHODS:The authors performed a retrospective study of Orthopedic United Healthcare patients diagnosed with thoracic or lumbar fracture. Patients were filtered into thoracic and lumbar fracture groups using diagnostic codes and then assigned to one of 2 treatment subgroups (fusion surgery or no surgery) on the basis of procedural codes. Disc degeneration and follow-up surgery were recorded. Chi-square statistical analysis was used. RESULTS:Of 3699 patients diagnosed with a thoracic fracture, 117 (3.2%) underwent thoracic fusion and 3215 (86.9%) were treated nonsurgically. Within 3 years, 147 (4.6%) patients from the nonsurgical subgroup and fewer than 11 (0.9%-8.5%) from the fusion subgroup were diagnosed with thoracic disc degeneration. From the nonsurgical subgroup, 11 (0.3%) patients underwent a thoracic surgery related to disc degeneration compared with zero from the fusion group (p > 0.05). Of 5016 patients diagnosed with lumbar fracture, 150 (3.0%) underwent fusion and 4371 (87.1%) had no surgery. Within 3 years, 503 patients (11.5%) from the nonsurgical subgroup and 35 (23.3%) from the fusion subgroup were diagnosed with lumbar disc degeneration (p < 0.05). From the nonsurgical subgroup, 42 (1.0%) went on to have surgery related to disc degeneration, compared with fewer than 11 (0.7%-6.7%) from the fusion subgroup (values not precise due to privacy limitations). CONCLUSIONS:Fusion surgery for thoracic fracture does not appear to increase the likelihood of undergoing future surgery. In the lumbar region, initial fusion surgery appears to increase the incidence of disc degeneration and could potentially necessitate future surgeries.

PURPOSE/OBJECTIVE:A retrospective database review was carried out to evaluate the trends and demographics of rhBMP utilization in single-level posterior lumbar fusion (PLF) in the United States. METHODS:Patients who underwent single-level PLF from 2005 to 2011 were identified by searching ICD-9 diagnosis and procedure codes in the PearlDiver Patient Records Database (PearlDiver Technologies, Fort Wayne, IN, USA), a national database of orthopaedic insurance records. The year of procedure, age, gender, and region of the United States were recorded for each patient. Results were reported for each variable as the incidence of procedures identified per 100,000 patients searched in the database. RESULTS:Totally 5158 patients had single-level PLF in this study. The average rate of single-level PLF with rhBMP utilization maintained at a relatively stable level (19.1-23.5%) from 2005 to 2009, but sharply decreased to 6.8% in 2010 and 6.9% in 2011. The overall incidence of single-level PLF without rhBMP (1.37 cases per 100,000 patients) was more than five times of the incidence of single-level PLF with rhBMP (0.27 cases per 100,000 patients) (P < 0.01). The average rate of single-level PLF with rhBMP utilization is highest in Midwest (18.7%), followed by West (18.4%), South (16.4%) and Northeast (11.5%). The highest incidence of single-level PLF with rhBMP was observed in the group aged 70-74 years with an incidence of 0.33 per 100,000 patients. CONCLUSIONS:The incidence of rhBMP utilization in single-level PLF increased from 2006 to 2009, but dropped to a low level in 2010 and 2011. The Northeast region had the lowest incidence of rhBMP utilization. The group aged 70-74 years trended to have the higher incidence of single-level PLF with rhBMP utilization.

COMMENTARY ON/CONCLUSIONS:Wheeler DL, Fredericks DC, Dryer RF, Bae HW. Allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold to promote lumbar interbody spine fusion in an ovine model. Spine J 2016:16:389-99 (in this issue).

STUDY DESIGN/METHODS:A retrospective kinematic magnetic resonance imaging (kMRI) study. OBJECTIVE:To evaluate the utility of kMRI in determining the relationship between cervical sagittal balance and TI alignment. SUMMARY OF BACKGROUND DATA/BACKGROUND:Thoracic inlet parameters play an important role in cervical spine sagittal balance. However, most of the literature is based on lower resolution cervical X-rays or CT scans in the supine position. METHODS:Cervical spine kMRI of 83 patients with degenerative cervical spine conditions (20-68 yr of age) was analyzed for: (1) cervical spine parameters: C2-C7 angle, C2-C7 sagittal vertical axis (SVA), cranial tilt, and cervical tilt; and (2) T1 parameters: thoracic inlet angle (TIA), T1 slope, and neck tilt (NT). Multiple logistic regression analysis and Pearson correlation coefficients were performed. RESULTS:The mean TIA, T1 slope, and NT were 78.0, 33.2, and 44.8°, respectively. The mean C2-7 angle, SVA of C2-C7, cervical tilt, and cranial tilt were -15.4°, 22.0 mm, 18.1°, and 15.1°, respectively. The ratio of cervical:cranial tilt was maintained as 55:45%. A significant correlation was found between the C2-C7 angle and T1 slope (r = 0.731), TIA and C2-C7 angle (r = 0.406), cervical tilt with C2-C7 angle (r = 0.671), T1 slope with TIA (r = 0.429), TIA with neck tilt (r = 0.733), TIA with cervical tilt (r = 0.377), SVA C2-C7 with cervical tilt (r = -0.480), SVA C2-C7 with cranial tilt (r = 0.912), and C2-7 SVA with the ratio of cranial tilt to cervical tilt (r = 0.694). CONCLUSION/CONCLUSIONS:An individual with a large T1 slope required large cervical lordosis to preserve physiologic sagittal balance of the cervical spine. Cranial tilt was the cervical parameter most strongly correlated with SVA C2-C7, and thus may be a good parameter to assess decompensation of cervical sagittal balance. LEVEL OF EVIDENCE/METHODS:3.