Faculty Bibliography

INTRODUCTION: Posterior C1-C2 fusion is a highly successful treatment for atlantoaxial instability and other pathologies of the cervical spine, with fusion rates approaching 95%-100%. However, poor visualization of the lateral masses of C1 secondary to the course of the C2 nerve root along with blood loss from the venous plexus and compression of the C2 nerve from lateral mass screws are technical obstacles that can arise during surgery. Thus, sacrifice of the C2 nerve root has long since been debated in fusions involving the C1 and C2 vertebral bodies. METHODS: Cadaveric dissections on four adult specimens were performed. Both intradural and extradural courses of C2 were studied in detail. The tentative site of C2 nerve root compression during placement of C1 lateral mass screws was studied in detail. Both the indication as well as the ease of C2 neurectomy were studied in relation to postoperative compression and entrapment. RESULTS: Four-six dorsal rootlets of C2 nerve were observed while studying the intradural course. The extradural course was studied with respect to the lateral mass of C1. The greater occipital nerve (GON) course was fairly consistent in all specimens. Transection of C2 around its ganglion would allow for proper C1 lateral mass screw placement as the course of C2 nerve interferes with proper placement of instrumentation. CONCLUSION: C2 nerve root transection is associated with occipital numbness but this often has no effect on health-related quality of life (HRQOL). The C2 nerve root preservation is often associated with entrapment neuropathy or occipital neuralgia, which greatly affects HRQOL. The C2 nerve root transection helps in better visualization, aids in optimal placement of C1 lateral mass screws, minimizes estimated blood loss and improves surgical outcome with successful fusion.

STUDY DESIGN: Retrospective cohort study OBJECTIVE.: To assess factors potentially impacting the operative approach chosen for CSM patients on a nationwide level. SUMMARY OF BACKGROUND DATA: Cervical spondylotic myelopathy (CSM) is one of the most common spinal disorders treated by spine surgeons, with operative management consisting of three approaches: anterior-only, posterior-only, or combined anterior-posterior. It is unknown whether the operative approach used differs based on patient demographics and/or insurance status. METHODS: The Nationwide Inpatient Sample from 2001-2010 was used for analysis. Admissions having a diagnosis code of 721.1 and a primary procedure code of 81.02/81.03, 81.32/81.33, 81.02/81.03 or 81.32/81.33 (combined anterior and posterior fusion/refusion at C2 or below), and 3.09 (decompression of the spinal canal including laminoplasty) were included. Analysis was adjusted for several variables including patient age, race, sex, primary payer for care, and admission source/type. RESULTS: Multivariate analyses revealed that non-Caucasian race [Black (OR = 1.39;95%CI = 1.32-1.47;p < 0.0001), Hispanic (OR = 1.51;95%CI = 1.38-1.66;p < 0.0001), Asian/Pacific Islander (OR = 1.40;95%CI = 1.15-1.70;p = 0.0007), Native American (OR = 1.33;95%CI = 1.02-1.73;p = 0.037)] and increasing age (OR = 1.03; p < 0.0001) were predictive of receiving posterior-only approaches. Female sex (OR = 1.39;95%CI = 1.34-1.43;p < 0.0001), private insurance (OR = 1.19;95%CI = 1.14-1.25;p < 0.0001), and non-trauma center admission type (OR = 1.29-1.39;95%CI = 1.16-1.56;p < 0.0001) were independently predictive of increased likelihood of receiving an anterior-only approach. Hispanic race (OR = 1.35;95%CI = 1.14-1.59;p = 0.0004) and admission source [another hospital (OR = 1.65;95%CI = 1.20-2.27;p = 0.0023), other health facility (OR = 1.68;95%CI = 1.13-2.51;p = 0.011)] were the only variables predictive of increased combined anterior-posterior approaches; Native American race (OR = 0.32;95%CI = 0.13-0.78;p = 0.013) decreased the likelihood of a combined anterior-posterior approach. CONCLUSIONS: Private insurance status, female sex, and Caucasian race independently predict receipt of anterior-only CSM approaches, while non-Caucasian race (Black, Hispanic, Asian/Pacific Islander, Native American) and non-private insurance predict receiving posterior-only CSM approaches. Given recent literature demonstrating posterior-only approaches as predictive of increased mortality in CSM (Kaye et al., 2015), our findings indicate that for CSM patients, non-Caucasian race may significantly increase mortality risk, while private insurance status may significantly decrease the risk of mortality. Further prospective study will be needed to more definitively address these issues. LEVEL OF EVIDENCE: 3.

BACKGROUND CONTEXT: For C1-C2 (atlantoaxial) instability and other pathologies of axial spine, posterior C1-C2 instrumentation is a feasible approach with highly successful rate of cervical spine fusion. With technical expertise, the fusion rates approach 95%-100%. Nevertheless, poor visualization of lateral mass of C1 due to C2 nerve root and/or C2 ganglia, blood loss from venous plexus around vertebral artery and compression of C2 nerve from lateral mass screw are technical issues during posterior C1-C2 instrumentation. PURPOSE: Typically, these patients present with hypo or hyperesthesia in the distribution of C2 nerve referred to as greater occipital neuralgia. Even in adept surgical hands, the rates of C2 nerve dysfunction after posterior C1-2 fusions vary from 4-33%. We studied the usefulness and consequences of sacrificing the C2 nerve root and/or ganglion during C1-C2 instrumentation. STUDY DESIGN/SETTING: meta-analysis. PATIENT SAMPLE: not defined. OUTCOME MEASURES: The feasibility of C2 neurectomy was studied during posterior C1-C2 instrumentation and fusion. Estimated blood loss, operative time, postoperative hyperesthesia or hypoesthesia were also studied during the procedure. METHODS:We did MEDLINE literature search using keywords "C2 neurectomy" or "C2 ganglionectomy" or "C2 neurectomy during atlantoaxial instrumented fusion." We described our technique of sacrificing C2 nerve root and ganglion for posterior C1-C2 instrumentation and fusion. RESULTS: An extensive literature search and our experience conclude the feasibility of C2 neurectomy during placement of C1 lateral mass screws. However, in the absence of C2 neurectomy, postoperative occipital neuralgia significantly affects the functional outcome and quality of life in these patients. Complications were studied after C2 ganglionectomy and neurectomy in these patients. CONCLUSIONS: Neurectomy and/or ganglionectomy offer a reasonably safe dissection to avoid neural and vascular injury in C1-C2 disc space. It serves as an acceptable part of the operation in posterior C1-C2 instrumentation, in frail elderly or redoes procedures. Postoperative hypo or hyperesthesia could be associated with the procedure but it offers a complete relief from intractable C2 neuropathic pain. C2 neurectomy or ganglionectomy is associated with decrease blood loss and operative time

BACKGROUND: Surgical-site infections (SSIs) are a major cause of morbidity and mortality, increasing the length and cost of hospitalization. In patients undergoing spine surgery, there is limited large-scale data on patient-specific risk factors for SSIs. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was reviewed for all spinal operations between 2006 and 2012. The rates of 30 day surgical site infections were calculated, and univariate analysis of selected preoperative risk factors was performed. Multivariate analysis was then used to identify independent predictors of SSIs. RESULTS: 1110 of the 60179 patients (1.84%) had a postoperative wound infection. There were 527 (0.87%) deep and 590 (0.98%) superficial infections. Patients with infections had greater rates of sepsis, longer lengths of stay and more return visits to the operating room. Independent predictors of infection were female gender, inpatient status, insulin dependent diabetes, preoperative steroid use greater than 10 days, hematocrit less than 35, body mass index (BMI) greater than 30, wound class, ASA class, and operative duration. CONCLUSIONS: Analysis of a large national patient database revealed many independent risk factors for SSIs after spinal surgery. Some of these risk factors can be modified preoperatively to reduce the risk of postoperative infection.

BACKGROUND: A key component toward improving surgical outcomes is proper patient selection. Improved selection can occur through exploration of prognostic studies that identify variables which are associated with good or poorer outcomes with a specific intervention, such as lumbar discectomy. To date there are no guidelines identifying key prognostic variables that assist surgeons in proper patient selection for lumbar discectomy. The purpose of this study was to identify baseline characteristics that were related to poor or favourable outcomes for patients who undergo lumbar discectomy. In particular, we were interested in prognostic factors that were unique to those commonly reported in the musculoskeletal literature, regardless of intervention type. METHODS: This retrospective study analysed data from 1,108 patients who underwent lumbar discectomy and had one year outcomes for pain and disability. All patient data was part of a multicentre, multi-national spine repository. Ten relatively commonly captured data variables were used as predictors for the study: (1) age, (2) body mass index, (3) gender, (4) previous back surgery history, (5) baseline disability, unique baseline scores for pain for both (6) low back and (7) leg pain, (8) baseline SF-12 Physical Component Summary (PCS) scores, (9) baseline SF-12 Mental Component Summary (MCS) scores, and (10) leg pain greater than back pain. Univariate and multivariate logistic regression analyses were run against one year outcome variables of pain and disability. RESULTS: For the multivariate analyses associated with the outcome of pain, older patients, those with higher baseline back pain, those with lesser reported disability and higher SF-12 MCS quality of life scores were associated with improved outcomes. For the multivariate analyses associated with the outcome of disability, presence of leg pain greater than back pain and no previous surgery suggested a better outcome. CONCLUSIONS: For this study, several predictive variables were either unique or conflicted with those advocated in general prognostic literature, suggesting they may have value for clinical decision making for lumbar discectomy surgery. In particular, leg pain greater than back pain and older age may yield promising value. Other significant findings such as quality of life scores and prior surgery may yield less value since these findings are similar to those that are considered to be prognostic regardless of intervention type.

BACKGROUND CONTEXT: Surgical site infection (SSI) is an expensive complication associated with spine surgery. The application of intrawound vancomycin is rapidly emerging as a solution to reduce SSI following spine surgery. The impact of intrawound vancomycin has not been systematically studied in a well-designed multicenter study. PURPOSE: Our aim was to determine whether intrawound vancomycin application was associated with reduced risk of SSI in patients after spine surgery. STUDY DESIGN/SETTING: Multicenter retrospective study. PATIENT SAMPLE: Patients undergoing elective spine surgery over the period of four years at seven different sites across the United States were included in the study. OUTCOME MEASURES: The primary outcome was occurrence of SSI within postoperative 30 days; the secondary outcome included occurrence of SSI that necessitated return to the operating room (OR). METHODS: Patients were given standard IV antibiotics perioperatively and dichotomized based on whether intrawound vancomycin was applied. Multivariable random effect log-binomial regression analyses were conducted to determine the relative risk of having an SSI and an SSI with return to OR. A random effect was included a priori to account for clustering of patients within each site. Covariates significant at p<0.05 in bivariate regression analyses were entered into the multivariable model. Adding back in each excluded variable one at a time tested the stability of the final model. The fraction of the variance attributable to differences between sites was calculated by dividing the variance of the site random effect by the total variance in the model (site + participants). RESULTS: A total of 2,311 patients were included: 2,056 for degenerative spine pathologies (89%), 233 for trauma (10%) and 22 for tumor (1%). The mean number of levels exposed was 3.7 +/- 2.8. Eighty-three percent underwent arthrodesis of which 80% had insertion of instrumentation. The lumbar-sacral region was operated on in 65% of cases, cervical 27.5% and the thoracic region in 7.5%. The mean length of hospital stay was 5.6 days +/- 6.3 and 22.5% of patients were admitted to the ICU after surgery. Intrawound vancomycin was used in 45% of patients. The prevalence of SSI was 5.1% in absence of vancomycin use compared to 2.4% with intrawound vancomycin. The site-to-site variation in SSI ranged from 1.5% to 5.7%. In a multivariable random effect log-binomial regression model, the patients in whom intrawound vancomycin was not used (P<0.001, RR-2.3, CI-1.5-3.6), those with higher number of levels exposed (P=0.045, RR-1.1, CI 1.0-1.1), postoperative ICU admission (P=0.003, RR-2.1, CI-1.3-3.3) and obese patients (P=0.04, RR-1.8, CI-1.0-3.0) had higher risk of developing SSI. Using similar statistical methodology, the risk factors that contributed to need for return to OR to address an infection included: not applying intrawound vancomycin (P<0.001, RR-5.2, CI 2.6-10.4), having a higher number of levels operated on (P=0.001, RR-1.1, CI- 1.0-1.2) and admission to the ICU postoperatively (P=0.001, RR-2.5, CI-1.5-4.3). Geographical site contributed significantly to the model and accounted for 3% of the variance in SSI and 20% of the variance in SSI with return to the OR. CONCLUSIONS: Intrawound application of vancomycin after elective spine surgery was associated with reduced risk of SSI and return to OR associated with SSI, even after controlling for confounding variables