“July Effect” in Spinal Fusions: A Coarsened Exact-Matched Analysis

Neurosurgery 92:623–631, 2023

Few neurosurgical studies examine the July Effect within elective spinal procedures, and none uses an exact-matched protocol to rigorously account for confounders.

OBJECTIVE: To evaluate the July Effect in single-level spinal fusions, after coarsened exact matching of the patient cohort on key patient characteristics (including race and comorbid status) known to independently affect neurosurgical outcomes.

METHODS: Two thousand three hundred thirty-eight adult patients who underwent single-level, posterior-only lumbar fusion at a single, multicenter university hospital system were retrospectively enrolled. Primary outcomes included readmissions, emergency department visits, reoperation, surgical complications, and mortality within 30 days of surgery. Logistic regression was used to analyze month as an ordinal variable. Subsequently, outcomes were compared between patients with surgery at the beginning vs end of the academic year (ie, July vs April–June), before and after coarsened exact matching on key characteristics. After exact matching, 99 exactly matched pairs of patients (total n = 198) were included for analysis.

RESULTS: Among all patients, operative month was not associated with adverse postoperative events within 30 days of the index operation. Furthermore, patients with surgeries in July had no significant difference in adverse outcomes. Similarly, between exact-matched cohorts, patients in July were observed to have noninferior adverse postoperative events.

CONCLUSION: There was no evidence suggestive of a July Effect after single-level, posterior approach spinal fusions in our cohort. These findings align with the previous literature to imply that teaching hospitals provide adequate patient care throughout the academic year, regardless of how long individual resident physician assistants have been in their particular role.

Rod fractures in thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis

J Neurosurg Spine 38:217–229, 2023

Previous reports of rod fracture (RF) in adult spinal deformity are limited by heterogeneous cohorts, low follow-up rates, and relatively short follow-up durations. Since the majority of RFs present > 2 years after surgery, true occurrence and revision rates remain unclear. The objectives of this study were to better understand the risk factors for RF and assess its occurrence and revision rates following primary thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis (ASLS) in a prospective series with long-term follow-up.

METHODS Patient records were obtained from the Adult Symptomatic Lumbar Scoliosis–1 (ASLS-1) database, an NIH-sponsored multicenter, prospective study. Inclusion criteria were as follows: patients aged 40–80 years undergoing primary surgeries for ASLS (Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20 or Scoliosis Research Society-22r ≤ 4.0 in pain, function, and/or self-image) with instrumented fusion of ≥ 7 levels that included the sacrum/pelvis. Patients with and without RF were compared to assess risk factors for RF and revision surgery.

RESULTS Inclusion criteria were met by 160 patients (median age 62 years, IQR 55.7–67.9 years). At a median followup of 5.1 years (IQR 3.8–6.6 years), there were 92 RFs in 62 patients (38.8%). The median time to RF was 3.0 years (IQR 1.9–4.54 years), and 73% occurred > 2 years following surgery. Based on Kaplan-Meier analyses, estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Baseline radiographic, clinical, and demographic characteristics were similar between patients with and without RF. In Cox regression models, greater postoperative pelvic tilt (HR 1.895, 95% CI 1.196–3.002, p = 0.0065) and greater estimated blood loss (HR 1.02, 95% CI 1.005–1.036, p = 0.0088) were associated with increased risk of RF. Thirty-eight patients (61% of all RFs) underwent revision surgery. Bilateral RF was predictive of revision surgery (HR 3.52, 95% CI 1.8–6.9, p = 0.0002), while patients with unilateral nondisplaced RFs were less likely to require revision (HR 0.39, 95% CI 0.18–0.84, p = 0.016).

CONCLUSIONS This study provides what is to the authors’ knowledge the highest-quality data to date on RF rates following ASLS surgery. At a median follow-up of 5.1 years, 38.8% of patients had at least one RF. Estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Greater estimated blood loss and postoperative pelvic tilt were significant risk factors for RF. These findings emphasize the importance of long-term follow-up to realize the true prevalence and cumulative incidence of RF.

Longitudinal assessment of segmental motion of the cervical spine following total disc arthroplasty: a comparative analysis of devices

J Neurosurg Spine 37:556–562, 2022

Total disc arthroplasty (TDA) has been shown to be an effective and safe treatment for cervical degenerative disc disease at short- and midterm follow-up. However, there remains a paucity of literature reporting the differences between individual prosthesis designs with regard to device performance. In this study, the authors evaluated the longterm maintenance of segmental range of motion (ROM) at the operative cervical level across a diverse range of TDA devices.

METHODS In this study, the authors retrospectively evaluated all consecutive patients who underwent 1- or 2-level cervical TDA between 2005 and 2020 at a single institution. Patients with a minimum of 6 months of follow-up and lateral flexion/extension radiographs preoperatively, 2 months postoperatively, and at final follow-up were included. Radiographic measurements included static segmental lordosis, segmental range of motion (ROM) on flexion/extension, global cervical (C2–7) ROM on flexion/extension, and disc space height. The paired t-test was used to evaluate improvement in radiographic parameters. Subanalysis between devices was performed using one-way ANCOVA. Significance was determined at p < 0.05.

RESULTS A total of 85 patients (100 discs) were included, with a mean patient age of 46.01 ± 8.82 years and followup of 43.56 ± 39.36 months. Implantations included 22 (22.00%) M6-C, 51 (51.00%) Mobi-C, 14 (14.00%) PCM, and 13 (13.00%) ProDisc-C devices. There were no differences in baseline radiographic parameters between groups. At 2 months postoperatively, PCM provided significantly less segmental lordosis (p = 0.037) and segmental ROM (p = 0.039). At final follow-up, segmental ROM with both the PCM and ProDisc-C devices was significantly less than that with the M6-C and Mobi-C devices (p = 0.015). From preoperatively to 2 months postoperatively, PCM implantation led to a significant loss of lordosis (p < 0.001) and segmental ROM (p = 0.005) relative to the other devices. Moreover, a significantly greater decline in segmental ROM from 2 months postoperatively to final follow-up was seen with ProDiscC, while segmental ROM increased significantly over time with Mobi-C (p = 0.049).

CONCLUSIONS Analysis by TDA device brand demonstrated that motion preservation differs depending on disc design. Certain devices, including M6-C and Mobi-C, improve ROM on flexion/extension from preoperatively to postoperatively and continue to increase slightly at final follow-up. On the other hand, devices such as PCM and ProDisc-C contributed to greater segmental stiffness, with a gradual decline in ROM seen with ProDisc-C. Further studies are needed to understand how much segmental ROM is ideal after TDA for preservation of physiological cervical kinematics.


Minimally Invasive Transforaminal Lumbar Interbody Fusion: Cost of a Surgeon’s Learning Curve

World Neurosurg. (2022) 162:e1-e7

Minimally invasive transforaminal interbody fusion has become an increasingly common approach in adult degenerative spine disease but is associated with a steep learning curve. We sought to evaluate the impact of the learning experience on mean procedure time and mean cost associated with each procedure.

METHODS: We studied the first 100 consecutive minimally invasive transforaminal interbody fusion procedures of a single surgeon. We performed multivariable linear regression models, modeling operating time, and costs in function of the procedure order adjusted for patients’ age, sex, and number of surgical levels. The number of procedures necessary to attain proficiency was determined through a k-means cluster analysis. Finally, the total excess operative time and total excess cost until obtaining proficiency was evaluated.

RESULTS: Procedure order was found to impact procedure time and mean costs, with each successive case being associated with progressively less procedure time and cost. On average, each successive case was associated with a reduction in procedure time of 0.97 minutes (95% confidence interval 0.54e1.40; P < 0.001) and an average adjusted reduction in overall costs of $82.75 (95% confidence interval $35.93e129.57; P < 0.001). An estimated 58 procedures were needed to attain proficiency, translating into an excess procedure time of 2604.2 minutes (average of 45 minutes per case), overall costs associated with the learning experience of $226,563.8 (average of $3974.80 per case), and excess surgical cost of $125,836.6 (average of $2207.66 per case).

CONCLUSIONS: Successive cases were associated with progressively less procedure time and mean overall and surgical costs, until a proficiency threshold was attained.

Robotic-Assisted vs Nonrobotic-Assisted Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Cost-Utility Analysis

Neurosurgery 90:192–198, 2022

Management of degenerative disease of the spine has evolved to favor minimally invasive techniques, including nonrobotic-assisted and robotic-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Value-based spending is being increasingly implemented to control rising costs in the US healthcare system. With an aging population, it is fundamental to understand which procedure(s) may be most cost-effective.

OBJECTIVE: To compare robotic and nonrobotic MIS-TLIF through a cost-utility analysis.

METHODS: We considered direct medical costs related to surgical intervention and to the hospital stay, as well as 1-yr utilities. We estimated costs by assessing all cases involving adults undergoing robotic surgery at a single institution and an equal number of patients undergoing nonrobotic surgery, matched by demographic and clinical characteristics. We adopted a willingness to pay of $50 000/quality-adjusted life year (QALY). Uncertainty was addressed by deterministic and probabilistic sensitivity analyses.

RESULTS: Costs were estimated based on a total of 76 patients, including 38 undergoing robot-assisted and 38 matched patients undergoing nonrobot MIS-TLIF. Using point estimates, robotic surgery was projected to cost $21 546.80 and to be associated with 0.68 QALY, and nonrobotic surgery was projected to cost $22 398.98 and to be associated with 0.67 QALY. Robotic surgery was found to be more cost-effective strategy, with costeffectiveness being sensitive operating room/materials and room costs. Probabilistic sensitivity analysis identified robotic surgery as cost-effective in 63% of simulations.

CONCLUSION: Our results suggest that at a willingness to pay of $50 000/QALY, robotic assisted MIS-TLIF was cost-effective in 63% of simulations. Cost-effectiveness depends on operating room and room (admission) costs, with potentially different results under distinct neurosurgical practices.

Collaborative spinal robot system for laminectomy: a preliminary study

Neurosurg Focus 52 (1):E11, 2022

The application of robots in the field of pedicle screw placement has achieved great success. However, decompressive laminectomy, a step that is just as critical as pedicle screw placement, does not have a mature robot-assisted system. To address this lack, the authors designed a collaborative spine robot system to assist with laminectomy. In this study, they aimed to investigate the reliability of this novel collaborative spinal robot system and compare it with manual laminectomy (ML).

METHODS Thirty in vitro porcine lumbar vertebral specimens were obtained as experimental bone specimens. Robot-assisted laminectomy (RAL) was performed on the left side of the lamina (n = 30) and ML was performed on the right side (n = 30). The time required for laminectomy on one side, whether the lamina was penetrated, and the remaining thickness of the lamina were compared between the two groups.

RESULTS The time required for laminectomy on one side was longer in the RAL group than in the ML group (median 326 seconds [IQR 133 seconds] vs 108.5 seconds [IQR 43 seconds], p < 0.001). In the RAL group, complete lamina penetration occurred twice (6.7%), while in the ML group, it occurred 9 times (30%); the difference was statistically significant (p = 0.045). There was no statistically significant difference in the remaining lamina thickness between the two groups (median 1.035 mm [IQR 0.419 mm] vs 1.084 mm [IQR 0.383 mm], p = 0.842).

CONCLUSIONS The results of this study confirm the safety of this novel spinal robot system for laminectomy. However, its efficiency requires further improvement.

Double tubular minimally invasive spine surgery: a novel technique expands the surgical visual field during resection of intradural pathologies

J Neurosurg Spine 36:160–163, 2022

A major challenge of a minimally invasive spinal approach (MIS) is maintaining freedom of maneuverability through small operative corridors. Unfortunately, during tubular resection of intradural pathologies, the durotomy and its accompanying tenting sutures offer a smaller operating window than the maximum surface of the tube’s base. The objective of this study was to evaluate if a novel double tubular technique could expand the surgical visual field during MIS resection of intradural pathologies.

METHODS A total of 25 MIS resections of intradural extramedullary pathologies were included. A posterior tubular interlaminar fenestration was performed in all surgeries. A durotomy covering the whole diameter of the tubular base was the standard in all cases. After placement of two tenting sutures on each side of the durotomy and application of tension, the resulting surface of the achieved dura fenestration was measured after optical analysis of the intraoperative video. In the next step, a second tube, 2 mm thinner than and the same length as the first, was inserted telescopically into the first tube, resulting an angulated fulcrum effect on the tenting sutures.

RESULTS Optical surface analysis of the dura fenestration before and after the second tubular insertion verified a significant widening of the visual field of 43.1% (mean 18.84 mm2, 95% CI 16.8–20.8, p value < 0.001). There were no ruptured tenting sutures through the increased tension. Postoperative MRIs verified complete resection of the pathologies.

CONCLUSIONS Inserting a second tube telescopically during posterior minimally invasive tubular spinal intradural surgery leads to an angulated fulcrum effect on the dura tenting sutures which consequently increases the surface of the dura fenestration and induces a meaningful widening of the visual field.

Negligible Systemic Uptake of Suprafascial Vancomycin Powder Following Instrumented Posterior Spinal Fusion

Neurosurgery 89:967–972, 2021

Intrawound vancomycin powder is an emerging strategy to reduce surgical site infections (SSIs) in spine surgery. However, there are concerns relating to its safety profile and toxicity. Data on systemic uptake of suprafascially administered vancomycin powder following instrumented spinal fusion is lacking.

OBJECTIVE: To study the systemic uptake and safety of suprafascially administered vancomycin powder in the early postoperative phase following open instrumented posterior spinal fusion.

METHODS: This was a substudy of an ongoing randomized clinical trial. Eligible adult patients were randomized 1:1 to either receive suprafascial vancomycin powder before wound closure or not to receive vancomycin powder. Serum vancomycin levels were assessed on postoperative days 1 and 2, serum creatinine levels were measured pre- and post-operatively. Adverse events up to 6 wk following surgery were recorded.

RESULTS:Among34 randomized patients (mean age 62 yr, range 31-84 yr; 18 [53%]women), 17 received vancomycin powder. No detectable serum vancomycin levels (>4.0mg/L)were found. Proportion of adverse events per patient in the vancomycin and control group, respectively,were 29.4% (5/17) vs 11.8% (2/17) (OR 3.12;95%CI, 0.52; 19.38; P=.398).No patient had nephrotoxicity or ototoxicity in either group. CONCLUSION: Suprafascial vancomycin powder in open instrumented spinal fusion surgery is safe and results in negligible systemic uptake. Final results of the VANCO Trial need to be awaited for conclusive data on the efficacy of vancomycin for SSI prevention and its impact on wound healing.


Surgery for Degenerative Cervical Myelopathy: A Nationwide Registry-Based Observational Study With Patient-Reported Outcomes

Neurosurgery 89:704–711, 2021

Indications and optimal timing for surgical treatment of degenerative cervical myelopathy (DCM) remain unclear, and data from daily clinical practice are warranted.

OBJECTIVE: To investigate clinical outcomes following decompressive surgery for DCM.

METHODS: Data were obtained from the Norwegian Registry for Spine Surgery. The primary outcome was change in the neck disability index (NDI) 1 yr after surgery. Secondary endpoints were the European myelopathy score (EMS), quality of life (EuroQoL 5D [EQ- 5D]), numeric rating scales (NRS) for headache, neck pain, and arm pain, complications, and perceived benefit of surgery assessed by the Global Perceived Effect (GPE) scale.

RESULTS: We included 905 patients operated between January 2012 and June 2018. There were significant improvements in all patient-reported outcome measures (PROMs) including NDI (mean −10.0, 95% CI −11.5 to −8.4, P < .001), EMS (mean 1.0, 95% CI 0.8-1.1, P < .001), EQ-5D index score (mean 0.16, 95% CI 0.13-0.19, P < .001), EQ-5D visual analogue scale (mean 13.8, 95% CI 11.7-15.9, P < .001), headache NRS (mean −1.1, 95% CI −1.4 to −0.8, P < .001), neck pain NRS (mean −1.8, 95% CI −2.0 to −1.5, P < .001), and arm pain NRS (mean −1.7, 95% CI −1.9 to −1.4, P < .001). According to GPE scale assessments, 229/513 patients (44.6%) experienced “complete recovery” or felt “much better” at 1 yr. There were signif- icant improvements in all PROMs for both mild and moderate-to-severe DCM. A total of 251 patients (27.7%) experienced adverse effects within 3 mo.

CONCLUSION: Surgery for DCM is associated with significant and clinically meaningful improvement across a wide range of PROMs.

Predicting Spinal Surgery Candidacy From Imaging Data Using Machine Learning

Neurosurgery 89:116–121, 2021

The referral process for consultation with a spine surgeon remains inefficient, given a substantial proportion of referrals to spine surgeons are nonoperative.

OBJECTIVE: To develop a machine-learning-based algorithm which accurately identifies patients as candidates for consultation with a spine surgeon, using only magnetic resonance imaging (MRI).

METHODS: We trained a deep U-Net machine learning model to delineate spinal canals on axial slices of 100 normal lumbar MRI scans which were previously delineated by expert radiologists and neurosurgeons. We then tested the model against lumbar MRI scans for 140 patients who had undergone lumbar spine MRI at our institution (60 of whom ultimately underwent surgery, and 80 of whom did not). The model generated automated segmentations of the lumbar spinal canals and calculated a maximum degree of spinal stenosis for each patient,which served as our biomarker for surgical pathology warranting expert consultation.

RESULTS: Themachine learning model correctly predicted surgical candidacy (ie, whether patients ultimately underwent lumbar spinal decompression) with high accuracy (area under the curve = 0.88), using only imaging data from lumbar MRI scans.

CONCLUSION: Automated interpretation of lumbar MRI scans was sufficient to correctly determine surgical candidacy in nearly 90% of cases. Given that a significant proportion of referrals placed for spine surgery evaluation fail to meet criteria for surgical intervention, our model could serve as a valuable tool for patient triage and thereby address some of the inefficiencies within the outpatient surgical referral process.

Effect of Incisional Negative Pressure Wound Therapy vs Standard Wound Dressing on the Development of Surgical Site Infection after Spinal Surgery: A Prospective Observational Study

Neurosurgery 88:E445–E451, 2021

Use of a closed-incisional negative pressure therapy (ci-NPT) dressing is an emerging strategy to reduce surgical site infections (SSIs) in spine surgery that lacks robust data.

OBJECTIVE: To determine the impact of a ci-NPT, as compared with a standard dressing, on the development of SSIs after spine surgery.

METHODS: This was a prospective observational study over a 2-yr period. Indications for surgery included degenerative disease, deformity, malignancy, and trauma. Exclusion criteria included anterior and lateral approaches to the spine, intraoperative durotomy, or use of minimally invasive techniques. SSIs up to 60d following surgery were recorded.

RESULTS: A total of 274 patients were included. SSI rate was significantly lower with ci-NPT dressing (n = 118) as compared with the standard dressing (n = 156) (3.4 vs 10.9%, P = .02). There was no statistical difference in infection rate for decompression alone procedures (4.2 vs 9.1%, P = .63), but there was a statistically significant reduction with the use of a negative-pressure dressing in cases that required instrumentation (3.2 vs 11.4%, P = .03). Patients at higher risk (instrumentation, deformity, and malignancy) had less SSIs with the use of ci-NPT, although this did not reach statistical significance. There were no complications in either group.

CONCLUSION: SSI rates were significantly reduced with a ci-NPT dressing vs a standard dressing in patients who underwent spinal surgery. The higher cost of a ci-NPT dressing might be justified with instrumented cases, as well as with certain high-risk patient populations undergoing spine surgery, given the serious consequences of an infection.

Intrawound vancomycin application after spinal surgery: a propensity score–matched cohort analysis

J Neurosurg Spine 34:788–798, 2021

Surgical site infection (SSI) following spine surgery is associated with increased morbidity and healthcare costs. In an effort to reduce SSI rates, the application of intrawound vancomycin powder has gained popularity. However, there is limited high-quality evidence to support the safety and efficacy of this practice. The authors sought to determine if intrawound application of vancomycin powder improves 90-day overall SSI rates.

METHODS The authors performed a retrospective, vancomycin exposure–matched cohort study at a single tertiary care hospital over 21 months. They included all patients undergoing elective spinal surgery and stratified the patients into two groups: those who received intrawound vancomycin powder application and those who received no application of vancomycin powder. The primary outcome of interest was the 90-day overall SSI rate. Secondary outcomes included rates of superficial SSI, deep SSI, wound disruption, and a post hoc analysis of the microbiology and minimum inhibitory concentrations. Baseline patient demographics, clinical presentation, comorbidities, perioperative factors, and 90-day postoperative outcomes were manually abstracted from patient charts. To mitigate bias, we performed 1:1 matching after calculating propensity scores and identified 1 patient from the no-vancomycin cohort for each patient in the vancomycin cohort.

RESULTS A total of 997 patients met our inclusion criteria (473 patients receiving vancomycin and 524 patients not receiving vancomycin). Propensity score matching produced 221 matched pairs. Risk-adjusted analysis demonstrated similar overall SSI rates between the groups (OR 1.9, p = 0.329). On unadjusted analysis, the overall 90-day SSI rate was greater in the vancomycin group (n = 10 [4.5%]) than in the no-vancomycin group (n = 5 [2.3%]) (p < 0.001), as were the superficial SSI rate (7 [3.2%] vs 4 [1.8%], p < 0.001), deep SSI rate (3 [1.4%] vs 1 [0.5%], p < 0.001), and wound disruption rate (5 [2.3%] vs 1 [0.5%], p < 0.001). No cultured isolate demonstrated vancomycin resistance.

CONCLUSIONS The authors observed no difference in SSI rates after the intrawound application of vancomycin powder during spine surgery. Vancomycin use did not contribute to antimicrobial resistance; however, it may select out gram negative bacteria and increase rates of wound disruption.

Telemedicine in the Evaluation and Management of Neurosurgical Spine Patients

Spine 2021;46:472–477

Study Design. Retrospective questionnaire study of all patients seen via telemedicine during the COVID-19 pandemic at a large academic institution.

Objective. This aim of this study was to compare patient satisfaction of telemedicine clinic to in-person visits; to evaluate the preference for telemedicine to in-person visits; to assess patients’ willingness to proceed with major surgery and/or a minor procedure based on a telemedicine visit alone.

Summary of Background Data. One study showed promising utility of mobile health applications for spine patients. No studies have investigated telemedicine in the evaluation and management of spine patients.

Methods. An 11-part questionnaire was developed to assess the attitudes toward telemedicine for all patients seen within a 7- week period during the COVID-19 crisis. Patients were called by phone to participate in the survey. x2 and the Wilcoxon Rank-Sum Test were performed to determine significance.

Results. Ninety-five percent were ‘‘satisfied’’ or ‘‘very satisfied’’ with their telemedicine visit, with 62% stating it was ‘‘the same’’ or ‘‘better’’ than previous in-person appointments. Patients saved a median of 105 minutes by using telemedicine compared to inperson visits. Fifty-two percent of patients have to take off work for in-person visits, compared to 7% for telemedicine. Thirtyseven percent preferred telemedicine to in-person visits. Patients who preferred telemedicine had significantly longer patient reported in-person visit times (score mean of 171) compared to patients who preferred in-person visits (score mean of 137, P=0.0007). Thirty-seven percent of patients would proceed with surgery and 73% would proceed with a minor procedure based on a telemedicine visit alone.

Conclusion. Telemedicine can increase access to specialty care for patients with prolonged travel time to in-person visits and decrease the socioeconomic burden for both patients and hospital systems. The high satisfaction with telemedicine and willingness to proceed with surgery suggest that remote visits may be useful for both routine management and initial surgical evaluation for spine surgery candidates.

Level of Evidence: 3

Development and validation of a clinical prediction score for poor postoperative pain control following elective spine surgery

J Neurosurg Spine 34:3–12, 2021

Thirty percent to sixty-four percent of patients experience poorly controlled pain following spine surgery, leading to patient dissatisfaction and poor outcomes. Identification of at-risk patients before surgery could facilitate patient education and personalized clinical care pathways to improve postoperative pain management. Accordingly, the aim of this study was to develop and internally validate a prediction score for poorly controlled postoperative pain in patients undergoing elective spine surgery.

METHODS A retrospective cohort study was performed in adult patients (≥ 18 years old) consecutively enrolled in the Canadian Spine Outcomes and Research Network registry. All patients underwent elective cervical or thoracolumbar spine surgery and were admitted to the hospital. Poorly controlled postoperative pain was defined as a mean numeric rating scale score for pain at rest of > 4 during the first 24 hours after surgery. Univariable analysis followed by multivariable logistic regression on 25 candidate variables, selected through a systematic review and expert consensus, was used to develop a prediction model using a random 70% sample of the data. The model was transformed into an eight-tier risk-based score that was further simplified into the three-tier Calgary Postoperative Pain After Spine Surgery (CAPPS) score to maximize clinical utility. The CAPPS score was validated using the remaining 30% of the data.

RESULTS Overall, 57% of 1300 spine surgery patients experienced poorly controlled pain during the first 24 hours after surgery. Seven significant variables associated with poor pain control were incorporated into a prediction model: younger age, female sex, preoperative daily use of opioid medication, higher preoperative neck or back pain intensity, higher Patient Health Questionnaire–9 depression score, surgery involving ≥ 3 motion segments, and fusion surgery. Notably, minimally invasive surgery, body mass index, and revision surgery were not associated with poorly controlled pain. The model was discriminative (C-statistic 0.74, 95% CI 0.71–0.77) and calibrated (Hosmer-Lemeshow goodness-of-fit, p = 0.99) at predicting the outcome. Low-, high-, and extreme-risk groups stratified using the CAPPS score had 32%, 63%, and 85% predicted probability of experiencing poorly controlled pain, respectively, which was mirrored closely by the observed incidence of 37%, 62%, and 81% in the validation cohort.

CONCLUSIONS Inadequate pain control is common after spine surgery. The internally validated CAPPS score based on 7 easily acquired variables accurately predicted the probability of experiencing poorly controlled pain after spine surgery.

A high-definition 3D exoscope as an alternative to the operating microscope in spinal microsurgery

J Neurosurg Spine 33:705–714, 2020

Since the 1970s, the operating microscope (OM) has been a standard for visualization and illumination of the surgical field in spinal microsurgery. However, due to its limitations (e.g., size, costliness, and the limited movability of the binocular lenses, in addition to discomfort experienced by surgeons due to the posture required), there are efforts to replace the OM with exoscopic video telescopes. The authors evaluated the feasibility of a new 3D exoscope as an alternative to the OM in spine surgeries.

METHODS Patients with degenerative pathologies scheduled for single-level lumbar or cervical spinal surgery with use of a high-definition 3D exoscope were enrolled in a prospective cohort study between January 2019 and September 2019. Age-, sex-, body mass index–, and procedure-matched patients surgically treated with the assistance of the OM served as the control group. Operative baseline and postoperative outcome parameters were assessed. Periprocedural handling, visualization, and illumination by the exoscope, as well as surgeons’ comfort level in terms of posture, were scored using a questionnaire.

RESULTS A 3D exoscope was used in 40 patients undergoing lumbar posterior decompression (LPD) and 20 patients undergoing anterior cervical discectomy and fusion (ACDF); an equal number of controls in whom an OM was used were studied. Compared with controls, there were no significant differences for mean operative time (ACDF: 132 vs 116 minutes; LPD: 112 vs 113 minutes) and blood loss (ACDF: 97 vs 93 ml; LPD: 109 vs 55 ml) as well as postoperative improvement of symptoms (ACDF/Neck Disability Index: p = 0.43; LPD/Oswestry Disability Index: p = 0.76). No intraoperative complications occurred in either group. According to the attending surgeon, the intraoperative handling of instruments was rated to be comparable to that of the OM, while the comfort level of the surgeon’s posture intraoperatively (especially during “undercutting” procedures) was rated as superior. In cases of ACDF procedures and long approaches, depth perception, image quality, and illumination were rated as inferior when compared with the OM. By contrast, for operating room nursing staff participating in 3D exoscope procedures, the visualization of intraoperative process flow and surgical situs was rated to be superior to the OM, especially for ACDF procedures.

CONCLUSIONS A 3D exoscope seems to be a safe alternative for common spinal procedures with the unique advantage of excellent comfort for the surgical team, but the drawback is the still slightly inferior visualization/illumination quality compared with the OM.

Spine surgery is kyphosing to spine surgeon

Acta Neurochirurgica (2020) 162:967–971

Spine surgery is a demanding surgical specialty which requires surgeons to operate for hours on end, often compromising good posture. Sustained poor posture in the operating room (OR) can be the source of many adverse health effects on spine surgeons. This study will analyze posture of a spine surgeon in different types of spine surgery cases.

Methods Posture of a surgeon was measured using the UPRIGHT Posture Training Device. The device was worn by the surgeon in the OR through a wide variety of spine surgery cases.

Results The percent time spent slouched while performing cervical, adult deformity, and lumbar spine surgeries is 39.9, 58.9, and 38.6, respectively. For all surgeries recorded, the percent time slouched is 41.6. The average procedure time was 145.3 min, with adult deformity cases on average being the longest (245.6 min) followed by cervical (152.9 min) and then lumbar (122.5 min).

Conclusion Poor posture while operating is very likely to occur for many spine surgeons regardless of case type. This poor posture is maintained for long periods of time given the average spine surgery procedure recorded in the study was roughly 2.5 h long. Spine surgeons should be aware of the tendency for poor posture while operating, and they should try using postureimproving techniques to maintain good spine health.


Usefulness of Timed Up and Go (TUG) Test for Prediction of Adverse Outcomes in Patients Undergoing Thoracolumbar Spine Surgery

Neurosurgery 2019 DOI:10.1093/neuros/nyz480

Spine surgery rates have increased and the high postoperativemorbidity in these patients result in increased costs. Consequently, it is essential to identify patients at risk of adverse outcomes.

OBJECTIVE: To assess whether preoperative Timed Up and Go (TUG) test performance can predict high-grade postoperative complications.

METHODS: A prospective cohort study of patients undergoing elective thoracolumbar spine surgery in a tertiary care hospital between 2017 and 2018. Patients were assessed preoperatively and assigned to the slow-TUG group if unable to perform or test performance time was ≥18.4 s. Primary outcome: high-grade postoperative complications. Secondary outcomes: overall complications, length of stay (LOS), discharge to healthcare facility, readmission and emergency department (ED) presentation. Patients were followed-up until 6 wk after surgery.

RESULTS: One hundred three patients (mean age 62.95 ± 10.97 yr) were enrolled. Slow- TUG group were more likely to be classified as American Society of Anaesthesiology (ASA) class 3 (74.1% vs 47.4%, P=.02), non-independent (25.9% vs 5.3%, P<.01), and frail (92.3% vs 42.1%, P < .01). TUG was an independent predictor of high-grade complications (adjusted odds ratio (OR): 4.97, 95% CI: 1.18-22.47), overall complications (OR: 3.77, 95% CI: 1.33-11.81), discharge to a skilled-nursing facility (OR: 3.2, 95% CI: 1.00-10.70), readmission within 6 wk of surgery (OR: 9.14, 95% CI: 2.39-41.26) and LOS (adjusted incident rate ratio (IRR): 1.45, 95% CI: 1.16-1.80).

CONCLUSION: Compared to traditional risk factors, TUG is an important predictor of adverse postoperative outcomes and may be used preoperatively to identify high-risk thoracolumbar surgery patients.


Outcomes of endoscopic discectomy compared with open microdiscectomy and tubular microdiscectomy for lumbar disc herniations: a meta-analysis

J Neurosurg Spine 31:802–815, 2019

Endoscopic discectomy (ED) has been advocated as a less-invasive alternative to open microdiscectomy (OM) and tubular microdiscectomy (TM) for lumbar disc herniations, with the potential to decrease postoperative pain and shorten recovery times. Large-scale, objective comparisons of outcomes between ED, OM, and TM, however, are lacking. The authors’ objective in this study was to conduct a meta-analysis comparing outcomes of ED, OM, and TM.

METHODS The PubMed database was searched for articles published as of February 1, 2019, for comparative studies reporting outcomes of some combination of ED, OM, and TM. A meta-analysis of outcome parameters was performed assuming random effects.

RESULTS Twenty-six studies describing the outcomes of 2577 patients were included. Estimated blood loss was significantly higher with OM than with both TM (p = 0.01) and ED (p < 0.00001). Length of stay was significantly longer with OM than with ED (p < 0.00001). Return to work time was significantly longer in OM than with ED (p = 0.001). Postoperative leg (p = 0.02) and back (p = 0.01) VAS scores, and Oswestry Disability Index scores (p = 0.006) at latest follow-up were significantly higher for OM than for ED. Serum creatine phosphokinase (p = 0.02) and C-reactive protein (p < 0.00001) levels on postoperative day 1 were significantly higher with OM than with ED.

CONCLUSIONS Outcomes of TM and OM for lumbar disc herniations are largely equivalent. While this analysis demonstrated that several clinical variables were significantly improved in patients undergoing ED when compared with OM, the magnitude of many of these differences was small and of uncertain clinical relevance, and several of the included studies were retrospective and subject to a high risk of bias. Further high-quality prospective studies are needed before definitive conclusions can be drawn regarding the comparative efficacy of the various surgical treatments for lumbar disc herniations.


Heterotopic ossification and radiographic adjacent-segment disease after cervical disc arthroplasty

J Neurosurg Spine 31:660–669, 2019

Cervical disc arthroplasty (CDA) is an accepted motion-sparing technique associated with favorable patient outcomes. However, heterotopic ossification (HO) and adjacent-segment degeneration are poorly understood adverse events that can be observed after CDA. The purpose of this study was to retrospectively examine 1) the effect of the residual exposed endplate (REE) on HO, and 2) identify risk factors predicting radiographic adjacent-segment disease (rASD) in a consecutive cohort of CDA patients.

METHODS A retrospective cohort study was performed on consecutive adult patients (≥ 18 years) who underwent 1- or 2-level CDA at the University of Calgary between 2002 and 2015 with > 1-year follow-up. REE was calculated by subtracting the anteroposterior (AP) diameter of the arthroplasty device from the native AP endplate diameter measured on lateral radiographs. HO was graded using the McAfee classification (low grade, 0–2; high grade, 3 and 4). Change in AP endplate diameter over time was measured at the index and adjacent levels to indicate progressive rASD.

RESULTS Forty-five patients (58 levels) underwent CDA during the study period. The mean age was 46 years (SD 10 years). Twenty-six patients (58%) were male. The median follow-up was 29 months (IQR 42 months). Thirty-three patients (73%) underwent 1-level CDA. High-grade HO developed at 19 levels (33%). The mean REE was 2.4 mm in the high-grade HO group and 1.6 mm in the low-grade HO group (p = 0.02). On multivariable analysis, patients with REE > 2 mm had a 4.5-times-higher odds of developing high-grade HO (p = 0.02) than patients with REE ≤ 2 mm. No significant relationship was observed between the type of artificial disc and the development of high-grade HO (p = 0.1). RASD was more likely to develop in the lower cervical spine (p = 0.001) and increased with time (p < 0.001). The presence of an artificial disc was highly protective against degenerative changes at the index level of operation (p < 0.001) but did not influence degeneration in the adjacent segments.

CONCLUSIONS In patients undergoing CDA, high-grade HO was predicted by REE. Therefore, maximizing the implant-endplate interface may help to reduce high-grade HO and preserve motion. RASD increases in an obligatory manner following CDA and is highly linked to specific levels (e.g., C6–7) rather than the presence or absence of an adjacent arthroplasty device. The presence of an artificial disc is, however, protective against further degenerative change at the index level of operation.

Surgical correction of severe adult lumbar scoliosis (major curves ≥ 75°): retrospective analysis with minimum 2-year follow-up

J Neurosurg Spine 31:548–561, 2019

Prior reports have demonstrated the efficacy of surgical correction for adult lumbar scoliosis. Many of these reports focused on mild to moderate scoliosis. The authors’ objective was to report their experience and to assess outcomes and complications after deformity correction for severe adult scoliosis.

METHODS The authors retrospectively analyzed consecutive adult scoliosis patients with major thoracolumbar/lumbar (TL/L) curves ≥ 75° who underwent deformity correction at their institution. Those eligible with a minimum 2 years of follow-up were included. Demographic, surgical, coronal and sagittal plane radiographic measurements, and healthrelated quality of life (HRQL) scores were analyzed.

RESULTS Among 26 potentially eligible patients, 22 (85%) had a minimum 2 years of follow-up (range 24–89 months) and were included in the study (mean age 57 ± 11 years; 91% women). The cohort comprised 16 (73%), 4 (18%), and 2 (9%) patients with adult idiopathic scoliosis, de novo degenerative scoliosis, and iatrogenic scoliosis, respectively. The surgical approach was posterior-only and multistage anterior-posterior in 18 (82%) and 4 (18%) patients, respectively. Three-column osteotomy was performed in 5 (23%) patients. Transforaminal and anterior lumbar interbody fusion were performed in 14 (64%) and 4 (18%) patients, respectively. All patients had sacropelvic fixation with uppermost instrumented vertebra in the lower thoracic spine (46% [10/22]) versus upper thoracic spine (55% [12/22]). The mean fusion length was 14 ± 3 levels. Preoperative major TL/L and lumbosacral fractional (L4–S1) curves were corrected from 83° ± 8° to 28° ± 13° (p < 0.001) and 34° ± 8° to 13° ± 6° (p < 0.001), respectively. Global coronal and sagittal balance significantly improved from 5 ± 4 cm to 1 ± 1 cm (p = 0.001) and 9 ± 8 cm to 2 ± 3 cm (p < 0.001), respectively. Pelvic tilt significantly improved from 33° ± 9° to 23° ± 10° (p < 0.001). Significant improvement in HRQL measures included the following: Scoliosis Research Society (SRS) pain score (p = 0.009), SRS appearance score (p = 0.004), and SF-12/ SF-36 physical component summary (PCS) score (p = 0.026). Transient and persistent neurological deficits occurred in 8 (36%) and 2 (9%) patients, respectively. Rod fracture/pseudarthrosis occurred in 6 (27%) patients (supplemental rods were utilized more recently in 23%). Revisions were performed in 7 (32%) patients.

CONCLUSIONS In this single-center surgical series for severe adult scoliosis (major curves ≥ 75°), a posterior-only or multistage anterior-posterior approach provided major curve correction of 66% and significant improvements in global coronal and sagittal spinopelvic alignment. Significant improvements were also demonstrated in HRQL measures (SRS pain, SRS appearance, and SF-12/SF-36 PCS). Complications and revisions were comparable to those of other reports involving less severe scoliosis. The results of this study warrant future prospective multicenter studies to further delineate outcomes and complication risks for severe adult scoliosis correction.

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