A Longer Duration of Myelopathy Symptoms is Associated With the Lack of Intraoperative Motor Evoked Potential Improvement During Decompressive Cervical Myelopathy Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: We aim to investigate the relationship between the intraoperative motor evoked potential (MEP) signal changes during surgical treatment of cervical myelopathy with postoperative functional outcomes and determine what factors correlate with MEP signal changes. SUMMARY OF BACKGROUND DATA: Intraoperative neurophysiologic monitoring with MEP for cervical cord decompression can potentially predict postoperative neurological complications. MATERIALS AND METHODS: We prospectively collected data from 114 consecutive cervical compressive myelopathy patients who underwent decompressive cervical spine surgery. Functional outcomes were measured preoperatively and postoperatively at the 6-month mark, using the modified Japanese Orthopedic Association score. RESULTS: Among the 114 patients, 87 patients showed significant MEP improvement, 1 patient with MEP degeneration, 3 patients with no change in MEP, and 23 patients with MEP change, but which eventually returned to baseline. Univariate analysis showed that patients with MEP improvement had similar 6-month functional and Japanese Orthopedic Association scores compared with patients who did not have MEP improvement. Critically, a longer duration of symptoms was shown to have a statistically significant relationship with patients who did not have MEP improvement on univariate analysis (49.2 wk in patients with no MEP improvement compared with 34.59 wk in patients with MEP improvement, P = 0.03) but this did not translate to differences in functional outcomes. There was also no statistically significant association between the functional outcome scores and demographics, surgical, or radiologic factors. CONCLUSIONS: Our study shows that the duration of symptoms is not attributed to lower functional outcomes but is associated with a lack of MEP improvement. LEVEL OF EVIDENCE: Level III.

Radiological and Clinical Outcomes comparing 2-level MIS Lateral and MIS Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spinal Stenosis.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVES: To compare early postoperative radiological and clinical outcomes between 2-level minimally invasive (MIS) trans-psoas lateral lumbar interbody fusion (LLIF) and MIS transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar spinal stenosis. METHODS: Fifty three consecutive patients undergoing 2-level lumbar interbody fusion from L3-L5 for degenerative lumbar spinal stenosis were enrolled. Twenty four patients underwent LLIF and 29 underwent TLIF. RESULTS: Operative time and length of stay were similar between LLIF and TLIF (272.8 ± 82.4 vs 256.1 ± 59.4 minutes; 5.5 ± 2.8 vs 4.7 ± 3.3 days, P > .05), whereas blood loss was lower for LLIF (229.0 ± 125.6 vs 302.4 ± 97.1mls, P = .026). Neurological deficits were more common in LLIF (9 vs 3, P = .025), whereas persistent deficits were rare for both (1 vs 1, P = 1). For both groups, all patient reported outcomes visual analogue scale (VAS back pain, VAS leg pain, ODI, SF-36 physical) improved from preoperative to 2-years postoperative (P < .05), with both groups showing no significant differences in extent of improvement for any outcome. Lateral lumbar interbody fusion demonstrated superior restoration of disc height (L3-L4: 4.1 ± 2.4 vs 1.2 ± 1.9 mm, P < .001; L4-L5: 4.6 ± 2.4 vs .8 ± 2.8 mm, P < .001), foraminal height (FH) (L3-L4: 3.5 ± 3.6 vs 1.0 ± 3.6 mm, P = .014; L4-L5: 3.0 ± 3.5 vs -.1 ± 4.4 mm, P = .0080), segmental lordosis (4.1 ± 6.4 vs -2.1 ± 8.1°, P = .005), lumbar lordosis (LL) (4.1 ± 7.0 vs -2.3 ± 12.6°, P = .026) and pelvic incidence-lumbar lordosis (PI-LL) mismatch (-4.1 ± 7.0 vs 2.3 ± 12.6°, P = .019) at 2-years follow-up. CONCLUSION: The superior radiological outcomes demonstrated by 2-level trans-psoas LLIF did not translate into difference in clinical outcomes compared to 2-level TLIF at the 2-years follow-up, suggesting both approaches are reasonable for 2-level lumbar interbody fusion in degenerative lumbar spinal stenosis.

Smoking Is Associated With Lower Satisfaction in Nondiabetic Patients Undergoing Minimally Invasive Single-level Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: This was a retrospective review of prospectively collected registry data. OBJECTIVE: The objective of this study was to investigate the effect of smoking on 2 years postoperative functional outcomes, satisfaction, and radiologic fusion in nondiabetic patients undergoing minimally invasive transforaminal lumbar interbody fusion (TLIF) for degenerative spine conditions. SUMMARY OF BACKGROUND DATA: There is conflicting data on the effect of smoking on long-term functional outcomes following lumbar fusion. Moreover, there remains a paucity of literature on the influence of smoking within the field of minimally invasive spine surgery. METHODS: Prospectively collected registry data of nondiabetic patients who underwent primary single-level minimally invasive TLIF in a single institution was reviewed. Patients were stratified based on smoking history. All patients were assessed preoperatively and postoperatively using the Numerical Pain Rating Scale for back pain and leg pain, Oswestry Disability Index, Short-Form 36 Physical and Mental Component Scores. Satisfaction was assessed using the North American Spine Society questionnaire. Radiographic fusion rates were compared. RESULTS: In total, 187 patients were included, of which 162 were nonsmokers, and 25 had a positive smoking history. In our multivariate analysis, smoking history was insignificant in predicting for minimal clinically important difference attainment rates in Physical Component Score and fusion grading outcomes. However, in terms of satisfaction score, positive smoking history remained a significant predictor (odds ratio=4.7, 95% confidence interval: 1.10-20.09, P=0.036). CONCLUSIONS: Nondiabetic patients with a positive smoking history had lower satisfaction scores but comparable functional outcomes and radiologic fusion 2 years after single-level TLIF. Thorough preoperative counseling and smoking cessation advice may help to improve patient satisfaction following minimally invasive spine surgery. LEVEL OF EVIDENCE: Level III-nonrandomized cohort study.

Shoulder Balance Following Correction Surgery for Adolescent Idiopathic Scoliosis: When Is It Achieved and Does the Type of Construct Matter?

STUDY DESIGN: This is a retrospective study. OBJECTIVE: This study aims to determine (1) when shoulder rebalancing occurs after adolescent idiopathic scoliosis (AIS) correction surgery and (2) whether shoulder asymmetry was influenced by the use of pedicle screws or hooks. SUMMARY OF BACKGROUND DATA: Postoperative shoulder imbalance is an important outcome of AIS correction surgery as it may influence a patient's appearance and satisfaction. MATERIALS AND METHODS: Seventy AIS patients undergoing AIS correction surgery at a single institution were retrospectively reviewed. Radiographic parameters were measured from anteroposterior x-rays at preoperative, immediate postoperative, 6 months postsurgery, and 12 months postsurgery. Shoulder parameters measured were: radiographic shoulder height (RSH), clavicle angle, coracoid height difference (CHD), and T1 tilt. The Cobb angle of the proximal thoracic curve, major thoracic curve, and thoracolumbar/lumbar curve. The percentage of correction was also calculated. RESULTS: Lateral shoulder asymmetry (RSH and CHD) changed significantly from preoperative to up to 6 months postsurgery. T1 tilt, a measure of medial shoulder asymmetry, did not change significantly. Postoperatively, the hook group attained significantly better shoulder balance than the screw group in terms of RSH and CHD up to 12 months postsurgery. However, the percentage correction of the major thoracic curve was significantly greater in the screw group than the hook group (hook: 62.2±18.4% vs. screw: 76.0±16.0%, P=0.007). CONCLUSIONS: Lateral shoulder rebalancing occurs up to 6 months after surgery. While thoracic pedicle screws offer greater correction of major AIS curves, hook constructs offer better postoperative shoulder symmetry. LEVEL OF EVIDENCE: III.

Does the Predominant Pain Location Influence Functional Outcomes, Satisfaction, and Return to Work After Minimally Invasive Transforaminal Lumbar Interbody Fusion For Degenerative Spondylolisthesis?

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: The objective of this study was to determine how different combinations of preoperative back pain (BP) and leg pain (LP) may influence functional outcomes, patient satisfaction and return to work (RTW) in patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) for degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: Surgical decision-making is often based on the traditional assumption that the predominance of lower extremity symptoms is a stronger indication for lumbar spine surgery. Surprisingly, there is a paucity of literature supporting this notion and the isolated impact of the preoperative pattern of pain on outcome remains unclear. METHODS: Prospectively collected data for patients who underwent primary MIS-TLIF for degenerative spondylolisthesis were reviewed. Patients were categorized into 3 groups depending on predominant pain location: LP predominant (LP>BP), back pain predominant [(BPP); BP>LP] and equal pain predominance (BP=LP). Patients were prospectively followed for at least 2 years. RESULTS: In total, 781 patients were included: 33.4% LP predominant, 28.7% BPP and 37.9% equal pain predominance cases. The BPP group was significantly younger (P=0.005) and showed a trend towards poorer baseline Short-Form-36 Mental Component Summary (P=0.069). After adjusting for baseline differences, there was no significant difference in BP, LP, Oswestry Disability Index (ODI), SF-36 Physical Component Summary, and SF-36 Mental Component Summary between the 3 groups at all time points (P>0.05) except for poorer 1-month ODI in the BPP group (P=0.010). The rate of minimal clinically important difference attainment for ODI and SF-36 Physical Component Summary, satisfaction, expectation fulfilment and RTW were also similar (P>0.05). CONCLUSIONS: The functional outcomes, quality of life and satisfaction after MIS-TLIF were similar, regardless of the predominant pain location. Equal proportions of patients achieved the minimal clinically important difference and RTW. In the context of proper indications, these results suggest that MIS-TLIF can be equally effective for patients with varying combinations of BP or LP. LEVEL OF EVIDENCE: Level III-nonrandomized cohort study.

Risk Factors of Postoperative Shoulder Imbalance in Adolescent Idiopathic Scoliosis: The Role of Sagittal Spinopelvic Parameters and Upper Instrumented Vertebrae Selection.

STUDY DESIGN: This is a retrospective study. OBJECTIVE: To determine (1) the independent risk factors of postoperative shoulder imbalance (PSI) after adolescent idiopathic scoliosis (AIS) correction surgery; and (2) whether the level of upper instrumented vertebrae (UIV) affects postoperative shoulder balance. SUMMARY OF BACKGROUND DATA: PSI is an important outcome of AIS correction surgery as it influences a patient's appearance and satisfaction. However, risk factors for PSI remain controversial and there are currently no studies evaluating the effect of sagittal spinopelvic parameters on PSI. Previous studies on the relationship between the level of UIV and PSI have also reported conflicting results. MATERIALS AND METHODS: Sixty-nine AIS patients undergoing correction surgery at a single institution were retrospectively reviewed. Radiographic parameters were measured on anteroposterior and lateral x-rays preoperatively, immediate postoperatively, and 12 months postoperatively. At 1 year follow-up, patients were divided into 2 groups based on their radiographic shoulder height (RSH): (1) PSI group (RSH ≥20 mm) and (2) non-PSI group (RSH <20 mm). RESULTS: On multivariate regression analysis, a lower postoperative main thoracic curve (MTC) [odds ratio (OR): 0.702, 95% confidence interval (CI): 0.519-0.949, P=0.022], greater percentage correction of MTC (OR: 1.526, 95% CI: 1.049-2.220, P=0.027) and higher postoperative sacral slope (OR: 1.364, 95% CI: 1.014-1.834, P=0.040) were identified as independent risk factors of PSI. When preoperative, postoperative, and absolute change in shoulder parameters were compared across the level of UIV, no significant differences were found regardless of the radiographic shoulder parameter analyzed. CONCLUSIONS: Lower postoperative MTC, greater percentage correction of MTC and higher postoperative sacral slope were independent risk factors of PSI. Shoulder balance and symmetry were not affected by the level of UIV selected. Relative curve correction is a more important consideration than UIV to avoid PSI after AIS correction surgery. LEVEL OF EVIDENCE: III.

Comparative Demographics and Outcomes of Minimally Invasive Transforaminal Lumbar Interbody Fusion in Chinese, Malays, and Indians.

STUDY DESIGN: This study carried out a retrospective review of prospectively collected registry data. OBJECTIVE: This study aimed to determine whether (1) utilization rates; (2) demographics and preoperative statuses; and (3) clinical outcomes differ among Chinese, Malays, and Indians undergoing minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). SUMMARY OF BACKGROUND DATA: There is a marked racial disparity in spine surgery outcomes between white and African American patients. Comparative studies of ethnicity have mostly been carried out in American populations, with an underrepresentation of Asian ethnic groups. It is unclear whether these disparities exist among Chinese, Malays, and Indians. METHODS: A prospectively maintained registry was reviewed for 753 patients who underwent primary MIS-TLIF for degenerative spondylolisthesis between 2006 and 2013. The cohort was stratified by race. Comparisons of demographics, functional outcomes, and patient satisfaction were performed preoperatively and 1 month, 3 months, 6 months, and 2 years postoperatively. RESULTS: Compared with population statistics, there was an overrepresentation of Chinese (6.6%) and an underrepresentation of Malays (5.0%) and Indians (3.5%) who underwent MIS-TLIF. Malays and Indians were younger and had higher body mass index at the time of surgery compared with Chinese. After adjusting for age, sex, and body mass index, Malays had significantly worse back pain and Indians had poorer Short-Form 36 Physical Component Summary compared with Chinese preoperatively. Chinese also had a better preoperative Oswestry Disability Index compared with the other races. Although significant differences remained at 1 month, there was no difference in outcomes up to 2 years postoperatively, except for a lower Physical Component Summary in Indians compared with Chinese at 2 years. The rate of minimal clinically important difference attainment, satisfaction, and expectation fulfillment was also comparable. At 2 years, 87.0% of Chinese, 76.9% of Malays, and 91.7% of Indians were satisfied. CONCLUSION: The variations in demographics, preoperative statuses, and postoperative outcomes between races should be considered when interpreting outcome studies of lumbar spine surgery in Asian populations. LEVEL OF EVIDENCE: Level III-nonrandomized cohort study.

Poorer Preoperative Function Leads to Delayed Return to Work After Anterior Cervical Discectomy and Fusion for Degenerative Cervical Myelopathy.

BACKGROUND: The factors that affect return to work (RTW) after anterior cervical discectomy and fusion (ACDF) for degenerative cervical myelopathy (DCM) remain unclear, especially in a non-Workers' Compensation setting. We aimed to (1) identify factors that influence RTW in patients undergoing ACDF (2) determine if early RTW plays a role in functional outcomes, quality of life, and satisfaction. METHODS: Prospectively collected data of 103 working adults who underwent primary ACDF for DCM were retrospectively reviewed. Patients were stratified into 2 groups: early RTW (≤60 days, n = 42) and late RTW (>60 days, n = 61). RESULTS: The mean time taken to RTW was 34.7 and 134.9 days in the early and late RTW groups, respectively (P < 0.001). The early RTW group had significantly better preoperative Japan Orthopaedic Association (JOA) score and Neck Disability Index (NDI) (P < 0.05) and showed a trend toward higher 36-Item Short Form Physical Component Summary (PCS) (P = 0.071). The early RTW group also had significantly better postoperative JOA, NDI, and PCS at 6 months and less arm pain along with a trend toward better NDI at 2 years (P = 0.055). However, there was no difference in the change in outcome scores and a similar proportion in each group attained the minimal clinically important difference for each metric. At 2 years, 85.7% and 77.0% were satisfied in the early and late RTW groups, respectively (P = 0.275). CONCLUSIONS: While working adults that RTW later tend to have poorer function preoperatively and up to 2 years postoperatively, surgeons may reassure them that they will likely experience the same degree of clinical improvement and level of satisfaction after ACDF. LEVEL OF EVIDENCE: Level 3, therapeutic study.

The Effect of Body Mass Index on Long-Term Patient-Reported Outcome Scores after Anterior Cervical Discectomy and Fusion in an Asian Population: A 2-Year Study.

STUDY DESIGN: Retrospective cohort study. PURPOSE: This study aims to analyze the relationship between body mass index (BMI) subjective patient-reported outcomes (PRO) after 1- and 2-level anterior cervical discectomy and fusion (ACDF). OVERVIEW OF LITERATURE: The prevalence of cervical spondylosis and ACDF in expected to continue rising among the aging population of Asia. Moreover, the prevalence of obesity is also increasing. However, limited information is available about the mechanism by which BMI affects PRO after ACDF. METHODS: Total 878 patients underwent ACDF between 2000 and 2015. After excluding patients with previous cervical instrumentation, >2 levels fused, missing BMI measurement, or neoplastic/trauma indication for surgery, 535 patients were included. The PRO measures of the Neck Disability Index, Numerical Pain Rating Scale (NPRS) for Neck Pain, NPRS for Limb Pain, American Academy of Orthopaedic Surgeons-Neurogenic Symptom Score, and Japanese Orthopaedic Association myelopathy score were used. Patients were grouped based on their preoperative BMI, as per the World Health Organization guidelines for Asian populations. PRO scores were collected preoperatively, at 6 months postoperatively, and 2 years postoperatively. A generalized linear model was used to analyze the relationship of BMI category with the individual score, accounting for several factors that are likely to affect the outcomes. RESULTS: Total 19 (3.4%) were underweight, 155 (28.0%) were normal weight, 112 (20.3%) were overweight, and 267 (48.3%) were obese. Patients across all BMI categories experienced significant and similar improvements in their postoperative PRO scores. There were no significant differences in the preoperative, 6-month postoperative, and 2-year postoperative PRO scores of the groups. Rate of reoperation was highest in patients with grade II obesity at 8.07%; however, the difference was not statistically significant. CONCLUSIONS: Irrespective of the BMI, all patients exhibited similar satisfactory outcomes following ACDF. The results support surgery in all subgroups of patients with symptomatic nerve compression in the cervical spine.

The patient acceptable symptom state for the Oswestry Disability Index following single-level lumbar fusion for degenerative spondylolisthesis.

BACKGROUND CONTEXT: The patient acceptable symptom state (PASS) is a valuable tool for interpreting patient-reported outcomes. Previous studies have attempted to define the PASS in a heterogenous cohort with various lumbar spinal disorders and surgical procedures. PURPOSE: We aimed to determine the PASS threshold for the Oswestry Disability Index (ODI) specifically for patients undergoing lumbar fusion for spondylolisthesis-associated functional disability. STUDY DESIGN: Retrospective review of prospectively collected registry data. PATIENT SAMPLE: There were 692 patients who underwent primary single-level minimally invasive transforaminal lumbar interbody fusion for degenerative spondylolisthesis between 2006 and 2014. OUTCOME MEASURES: The ODI was collected pre-operatively, at 6 months and 2 years postoperatively. An anchor question was adapted from the NASS questionnaire, "How would you rate the overall results of your treatment?" while a validation question was taken from the same questionnaire, "Has the surgery for your back condition met your expectations so far?" METHODS: Responses to the anchor question were used to determine whether a PASS was achieved. Receiver operating characteristics curve analysis was performed to assess the ability of the ODI to discriminate between an acceptable/unacceptable symptom state as well as to define PASS thresholds. Sensitivity analyses were performed for different follow-up periods (6 months, 2 years), subgroups (by age, gender, BMI, and comorbidity burden), baseline ODI tertiles, and an alternate definition of PASS. RESULTS: In total, 529 of 692 (76%) patients completed 2-year follow-up, of which, 89% considered their symptom state to be acceptable. Areas under the curve (AUC) ranged from 0.81 to 0.90 for all receiver operating characteristics analyses, indicating that the ODI had an excellent discriminative ability. The PASS threshold was ≤18.09 at 6 months (AUC 0.81, sensitivity 77%, specificity 72%) and ≤15.27 at 2 years (AUC 0.86, sensitivity 79%, specificity 79%). These thresholds proved to be robust in the sensitivity analyses, showing minimal variation across different patient subgroups and baseline score tertiles. CONCLUSIONS: Patients with an ODI of ≤15.27 can be considered to have achieved a PASS after lumbar fusion for degenerative spondylolisthesis. These findings will help surgeons to contextualize a patient's functional recovery after lumbar spine surgery and enable researchers to define clinically relevant benchmarks when designing trials utilizing the ODI.

Comparison of Outcomes Between Single-level Lateral Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion: A Meta-analysis and Systematic Review.

STUDY DESIGN: This is a meta-analysis and systematic review of the available literature. OBJECTIVE: This study aims to compare the clinical and radiologic outcomes of single-level lateral lumbar interbody fusion (LLIF) with single-level transforaminal lumbar interbody fusion (TLIF). SUMMARY OF BACKGROUND DATA: In the treatment of adult spinal deformity, LLIF allows interbody fusion while avoiding complications associated with an anterior or transforaminal approach, although the clinical outcomes of LLIF compared with other approaches have not been well established. METHODS: We searched PubMed, Embase, and Scopus for 385 unique studies. On the basis of our exclusion criteria, 8 studies remained for our systematic review. Data were analyzed using Review Manager 5.3 using Mantel-Haenszel statistics and random effect models. This study identified self-reported Visual Analog Scale (VAS), Oswestry Disability Index, length of stay, blood loss, complication rate, and radiologic parameters (disk height, lumbar lordosis, segmental lordosis). RESULTS: Our meta-analysis showed that LLIF contributed to decreased blood loss [mean difference (MD)=-67.62 mL, 95% confidence interval (CI): -104 to -30.90, P<0.001], superior restoration of segmental lordosis (MD=1.91 degrees, 95% CI: 0.71-3.10, P=0.002), lumbar lordosis (MD=1.95 degrees, 95% CI: 0.15-3.74, P=0.03), and disk height (MD=2.18 mm, 95% CI: 1.18-3.17, P<0.001) when compared with TLIF. However, current data suggests no significant difference in clinical outcomes between LLIF and TLIF based on overall complication rates (P=0.22), length of hospital stay (P=0.65), postoperative Oswestry Disability Index (P=0.13), postoperative VAS Back Pain (P=0.47) and VAS Leg Pain (P=0.16). CONCLUSIONS: LLIF is an increasingly popular option for single-level anterior column reconstruction. When compared with single-level TLIF, single-level LLIF is associated with greater changes in lumbar lordosis and disk height. The single-level LLIF is a viable alternative to TLIF, demonstrating comparable clinical outcomes and better restoration of spinopelvic parameters. LEVEL OF EVIDENCE: Level III.

Does the Predominant Pain Location Influence Functional Outcomes, Satisfaction and Return to Work After Anterior Cervical Discectomy and Fusion for Cervical Radiculopathy?

STUDY DESIGN: Retrospective review of prospectively-collected registry data. OBJECTIVES: The aim of this study was to determine how different combinations of preoperative neck pain (NP) and arm pain (AP) influence functional outcomes, patient satisfaction, and return-to-work in patients undergoing anterior cervical discectomy and fusion (ACDF) for degenerative cervical radiculopathy (DCR). SUMMARY OF BACKGROUND DATA: Surgeons often base decisions on the traditional belief that the predominance of radicular upper extremity symptoms is a stronger indication for cervical spine surgery than axial pain. However, there is a paucity of literature supporting this notion. METHODS: A prospectively maintained registry was reviewed for all patients who underwent primary ACDF for DCR. Patients were categorized into three groups depending on predominant pain location: AP predominant ([APP]; AP > NP), NP predominant ([NPP]; NP > AP), and equal pain predominance ([EPP]; NP = AP). Patients were prospectively followed for at least 2 years. RESULTS: In total, 303 patients were included: 27.4% APP, 38.9% NPP, and 33.7% EPP cases. The APP group was significantly older (P = 0.030), although there were no other preoperative differences among the three groups. After adjusting for baseline differences, the SF-36 Physical Component Summary was significantly better in the APP group at 6 months (P = 0.048) and 2 years (P = 0.039). In addition, they showed a trend towards better 6-month Neck Disability Index (P = 0.077) and 2-year SF-36 Mental Component Summary (P = 0.059). However, an equal proportion of patients in each group achieved the Minimal Clinically Important Difference for each outcome, were satisfied, and returned to work 2 years after surgery. CONCLUSION: Although patients with NPP had slightly poorer function and quality of life, all patients experienced a clinically meaningful improvement in patient-reported outcomes, regardless of the predominant pain location. High rates of satisfaction and return-to-work were also achieved. In the context of proper indications, these findings suggest that ACDF can be equally effective for DCR patients with varying combinations of NP or AP.Level of Evidence: 3.

Women Do Not Have Poorer Outcomes After Minimally Invasive Lumbar Fusion Surgery: A Five-Year Follow-Up Study.

BACKGROUND: Women undergoing lumbar spine surgery report greater preoperative pain and disability and have less improvement after surgery. There is a paucity of literature on sex-related differences after minimally invasive surgery transforaminal lumbar interbody fusion (MIS TLIF) surgery. We aim to determine whether sex influences outcome after MIS TLIF at 5-year midterm follow-up. METHODS: Prospectively collected registry data for 907 patients who underwent MIS TLIF at a single institution from 2004 to 2013 were reviewed. Of these, 296 patients (94 males and 202 females) were reviewed at 5-year follow-up. All patients were assessed preoperatively and postoperatively at 2 and 5 years. Data recorded included patient demographics, Oswestry Disability Index (ODI), Short-Form 36 Physical and Mental component scores (SF-36 PCS and MCS), and the North American Spine Society lumbar spine outcome assessment instrument. RESULTS: Females who underwent MIS TLIF were generally younger (females, 52.2 years; males, 56.1 years; P = .04). Females had significantly poorer preoperative ODI (females, 49.5; males, 41.5; P < .001) and SF-36 PCS (females, 31.9; males, 35.6; P < .01) and MCS (females, 44.9; males, 49.2; P < .01) scores. At 2-year and 5-year follow-up, there were no significant differences in ODI, SF-36, and pain scores between sexes. Both groups reported similar proportions that returned to work and returned to function. There were no differences in proportion of patients who were satisfied or had their expectations fulfilled. CONCLUSIONS: Women who undergo MIS TLIF have poorer preoperative function and quality of life than men. However, women demonstrated greater improvement after surgery, attaining similar clinical outcomes at 5-year follow-up. LEVEL OF EVIDENCE: 3.

What Are the Patient-reported Outcomes, Complications, and Radiographic Results of Lumbar Fusion for Degenerative Spondylolisthesis in Patients Younger Than 50 Years?

BACKGROUND: The number of young patients with degenerative lumbar spondylosis is expected to increase, and with it, the number of younger patients seeking surgical treatment is likely to rise. The goals of young patients with degenerative spondylolisthesis may differ from those of older patients, but little is known about the levels of pain and function, complication rates, or radiographic union that young patients achieve after interbody fusion. QUESTIONS/PURPOSES: (1) How likely were patients younger than 50 years to achieve a minimal clinically important difference (MCID) in improvement on any of several validated patient-reported outcomes scores after transforaminal lumbar interbody fusion for degenerative spondylolisthesis at a minimum of 2 years after surgery? (2) What proportion developed complications or underwent reoperations? (3) What proportion achieved radiographic fusion or developed adjacent-segment degeneration? METHODS: Longitudinally maintained institutional registry data of patients undergoing primary, single-level, transforaminal lumbar interbody fusion for degenerative spondylolisthesis at a single institution from 2006 to 2013 were studied in this retrospective case series. Of the 96 patients who met inclusion criteria, 14% (13 of 96) were missing follow-up data, leaving 83 patients younger than 50 years with complete clinical and radiological data at a minimum of 2 years (97%, 93 of 96 had sufficient data to assess complications and radiographic fusion). The mean age of the cohort was 44 ± 7 years. Radiological parameters for each patient with spondylolisthesis were recorded. Clinical outcomes such as the numeric rating scale for back pain and leg pain, Oswestry Disability Index (ODI) and SF-36 were assessed preoperatively and postoperatively at 1, 3, 6 months and 2 years. The proportion of patients who had an improvement greater than the MCID of each outcome instrument was then calculated. The occurrence of any medical, surgical or wound complications, and reoperations for any reason were recorded. Radiographic fusion using Bridwell grading and adjacent-segment degeneration were assessed by an independent observer not involved in clinical care. The mean follow-up was 5 ± 3 years. RESULTS: The proportions of patients younger than 50 years who achieved the MCID for the various patient-reported outcomes were 82% (68 of 83) for leg pain, 75% (62 of 83) for back pain, 87% (72 of 83) for ODI and 71% (59 of 83) for SF-36 physical component summary at 2 years. Two perioperative complications occurred, and two reoperations were performed for implant-related complications. A total of 85% (79 of 93) of young patients achieved stable fusion, 8% (seven of 93) had radiologic adjacent-segment degeneration, and one patient underwent a revision procedure. CONCLUSIONS: Young patients with lumbar degenerative spondylolisthesis commonly, but do not always, experience clinically meaningful gains in pain relief, function, and quality of life after transforaminal lumbar interbody fusion. A low risk of complications, reoperations, nonunion and adjacent-segment degeneration were also noted in this population. LEVEL OF EVIDENCE: Level III, therapeutic study.

Determination of the patient acceptable symptom state for the Japanese Orthopaedic Association Score in patients undergoing anterior cervical discectomy and fusion for cervical spondylotic myelopathy.

BACKGROUND CONTEXT: The patient acceptable symptom state (PASS) has gained attention as a valuable interpretation tool in spine research. While the PASS for the Japanese Orthopaedic Association (JOA) score has been recently proposed, previous analyses demonstrated a weak discriminative ability for the suggested threshold. PURPOSE: To define the PASS for the JOA score in patients undergoing anterior cervical discectomy and fusion (ACDF) for cervical spondylotic myelopathy (CSM). STUDY DESIGN: Retrospective review of prospectively collected registry data. PATIENT SAMPLE: 378 patients who underwent ACDF for cervical myelopathy between 2005 and 2014. OUTCOME MEASURES: The main outcome measure was the JOA score. The PASS anchor question was adapted from the NASS questionnaire, "How would you rate the overall results of your treatment?" and the validation question was adapted from same questionnaire, "Has the surgery for your neck condition met your expectation so far?" METHODS: Patients were assessed preoperatively, 6 months and 2 years postoperatively using the JOA. Responses to the anchor question were dichotomized and used as the external criterion in receiver operating characteristics (ROC) analysis to define thresholds on the JOA that corresponded to a PASS at 2 years postoperatively. Sensitivity analyses were carried out for various subgroups (based on age, gender, body mass index, comorbidities), preoperative myelopathy severity, time of follow-up (6 months and 2 years) and an alternate definition of PASS. RESULTS: Of the 378 patients, 312 (83%) completed 2-year follow-up, of which, 78.5% reported their current state as acceptable. The areas under the curve (AUC) for the ROCs were 0.72 to 0.83 for all analyses, indicating a good discriminative ability of the JOA when assessing if a satisfactory state was attained. The PASS threshold was ≥13.25 points at 6 months (AUC 0.74, sensitivity 78%, specificity 59%) and ≥14.25 points at 2 years (AUC 0.76, sensitivity 74%, specificity 66%). Sensitivity analyses revealed that the 14.25-point threshold on the JOA was robust. PASS responders were approximately 6 times more likely to be satisfied (adjusted OR 6.18, 95% CI 2.87-13.30) and 8 times more likely to have their expectation fulfilled (adjusted OR 8.23, 95% CI 3.81-17.77) compared with non-responders. CONCLUSIONS: This study validates the PASS threshold of 14.25 on the JOA in a robust analysis of a large cohort undergoing ACDF. This knowledge will enable clinicians to identify patients who have attained a satisfactory functional status after surgery for CSM and allow researchers to interpret studies utilizing the JOA from a patient-centered perspective.

Defining threshold values on the neck disability index corresponding to a patient acceptable symptom state in patients undergoing elective surgery for degenerative disorders of the cervical spine.

BACKGROUND CONTEXT: The patient acceptable symptom state (PASS) has emerged as a novel tool for interpreting patient-reported outcomes. While the minimal clinically important difference values for various spine outcome instruments have been defined, little is known about the PASS thresholds for these measures. PURPOSE: To define threshold values on the neck disability index (NDI) corresponding to a PASS in patients undergoing surgery for degenerative disorders of the cervical spine. STUDY DESIGN: Retrospective review of prospectively collected registry data. PATIENT SAMPLE: The sample includes 613 patients who underwent anterior cervical discectomy and fusion for degenerative spine conditions between 2005 and 2014. OUTCOME MEASURES: The main outcome measure was the NDI. The PASS anchor question was adapted from the NASS questionnaire, "How would you rate the overall results of your treatment?" and the validation question was adapted from the AAOS cervical spine questionnaire, "Would you have the same treatment again if you had the same condition?" METHODS: Patients were assessed preoperatively, 6 months and 2 years postoperatively using the NDI. Responses to the anchor question were dichotomized and used as the external criterion in receiver operating characteristics analysis to define thresholds on the NDI that corresponded to a PASS at 2 years postoperatively. Sensitivity analyses were carried out for various subgroups (age, gender, BMI, comorbidity status), baseline NDI (tertiles), time of follow-up (6 months and 2 years) and an alternate definition of PASS. RESULTS: Of the 613 patients, 503 (82%) completed 2-year follow-up, of which, 81% reported their current state as acceptable. The areas under the curve (AUC) for the receiver operating characteristics were 0.75 to 0.89 for all analyses, indicating a good ability of the NDI to discriminate between attaining a satisfactory state or not. The PASS threshold was ≤15 points at 6 months (AUC 0.81, sensitivity 73%, specificity 79%) and ≤17 points at 2 years (AUC 0.80, sensitivity 86%, specificity 65%). Sensitivity analyses revealed that the 17-point threshold on the NDI was robust. PASS responders were approximately 12 times more likely to be satisfied (adjusted odds ratio 12.11, 95% confidence intervals 6.96-21.07) and 6 times more willing to undergo surgery again (adjusted odds ratio 6.12, 95% confidence intervals 3.47-10.80) compared to nonresponders. CONCLUSIONS: Patients with a NDI of ≤17 consider their postoperative symptom state to be acceptable. This PASS threshold can be used alongside the minimal clinically important difference when defining treatment success in spine outcomes studies. At the individual level, this threshold provides clinically relevant benchmarks for surgeons when assessing a patient's postoperative recovery.

Predictors of Outcomes After Single-level Anterior Cervical Discectomy and Fusion for Cervical Spondylotic Myelopathy: A Multivariate Analysis.

STUDY DESIGN: This was a retrospective study that was carried out using prospectively collected registry data. OBJECTIVE: The objective of this study was to identify preoperative predictors of outcomes after anterior cervical discectomy and fusion (ACDF) for cervical spondylotic myelopathy. SUMMARY OF BACKGROUND DATA: Proper patient selection is paramount to achieving good surgical results. Identifying predictors of outcomes may aid surgical decision-making and facilitate counseling of patients to manage expectations. METHODS: Prospectively collected registry data of 104 patients who underwent single-level ACDF for cervical spondylotic myelopathy were reviewed. Outcomes assessed at 2 years were the presence of residual neck pain/arm pain (AP), and attainment of a minimal clinically important difference (MCID) for Neck Disability Index (NDI), Japanese Orthopaedic Association (JOA) score, and Physical Component Score (PCS) of SF-36, as well as patient satisfaction, fulfilment of expectations, willingness to undergo same surgery again, return to work (RTW), and return to function (RTF). Receiver operating characteristic curves and multivariate stepwise logistical regression were performed to identify independent predictors of each outcome using 22 covariates including demographics, comorbidities, and preoperative disease state. RESULTS: Lower preoperative NDI was predictive of the absence of residual neck pain/AP at 2 years. Higher preoperative JOA score was predictive of MCID attainment for PCS, satisfaction, expectation fulfilment, willingness to undergo the same surgery for same condition, and RTF. Poorer preoperative scores of NDI, JOA, and PCS were predictors of attaining MCID of the respective scores. Older patients were less likely to attain MCID for JOA. Higher preoperative AP was a risk factor for unsuccessful RTW. CONCLUSIONS: In general, the preoperative JOA score was the best predictor of outcomes after ACDF. A preoperative JOA cutoff value of 9.25-10.25 predicted satisfaction, expectation fulfilment, willingness to undergo same surgery, and RTF with at least 70% sensitivity and 50% specificity. These findings may aid surgeons in identifying patients at risk of a poor outcome and guide preoperative counseling to establish realistic expectations of the surgical outcome. LEVEL OF EVIDENCE: Level III-Non-randomized controlled cohort/follow-up study.

Elderly Patients Undergoing Minimally Invasive Transforaminal Lumbar Interbody Fusion May Have Similar Clinical Outcomes, Perioperative Complications, and Fusion Rates As Their Younger Counterparts.

BACKGROUND: Although several studies have suggested that minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) may be especially beneficial in the elderly population due to lower operative morbidity and faster postoperative recovery, there are limited studies investigating the functional outcomes, quality of life, and satisfaction in elderly patients after MIS-TLIF. Furthermore, existing studies had substantial clinical, diagnostic, and surgical heterogeneity. QUESTIONS/PURPOSES: We asked if elderly patients could experience comparable (1) patient-reported pain, disability and quality of life, (2) perioperative complications, and (3) radiological fusion rates as their younger counterparts after MIS-TLIF. METHODS: Prospectively collected registry data of patients undergoing primary, single-level, MIS-TLIF for degenerative spondylolisthesis between 2012 and 2014 were reviewed. We included 168 patients, 39 of whom were at least 70 years old. Of the 129 patients younger than 70 years old, propensity-score matching was used to select 39 younger controls with adjustment for sex, BMI, American Society of Anesthesiologists score, and baseline clinical outcomes. Perioperative complications and radiologic data were compared. RESULTS: There was no difference in back pain (mean difference -0.3 [95% confidence interval -1.0 to 0.5]; p = 0.52); leg pain (mean difference -0.1 [95% CI to 0.6-0.5]; p = 0.85); Oswestry Disability Index (mean difference -2.9 [95% CI -8.0 to 2.2]; p = 0.26); and SF-36 physical (mean difference 3.0 [95% CI -0.7 to 6.8]; p = 0.107); and mental component summary (mean difference 1.9 [95% CI -4.5 to 8.2]; p = 0.56); up to 2 years postoperatively; 85% of younger patients and 85% of elderly patients were satisfied (p > 0.99) while 87% and 80%, respectively, had fulfilled expectations (p = 0.36). Four perioperative adverse events occurred in each group. There was also no difference in the rate of fusion (87% in younger patients and 90% in elderly patients; p = 0.135). CONCLUSIONS: When clinical and surgical heterogeneity were minimized, elderly patients undergoing minimally invasive transforaminal lumbar interbody fusion not only had comparable rates of perioperative complications but also experienced similar improvements in pain, function, and quality of life. A high rate of satisfaction was achieved. LEVEL OF EVIDENCE: Level II, prognostic study.

Sagittally Balanced Degenerative Spondylolisthesis Patients With Increased Sacral Slope and Greater Lumbar Lordosis Experience Less Back Pain After Short-Segment Lumbar Fusion Surgery.

STUDY DESIGN: A retrospective review of prospectively collected registry data. OBJECTIVES: (1) Examine functional outcomes of patients with postoperative sacral slope (SS)<30 degrees versus SS≥30 degrees after single-level transforaminal lumbar interbody fusion (TLIF) for degenerative spondylolisthesis (DS); (2) determine the factors associated with SS at the last follow-up. SUMMARY OF BACKGROUND DATA: Few studies have examined the relationship between spinopelvic parameters and functional outcomes in patients with DS undergoing short-segment TLIF. Although SS of 30 degrees has been proposed as the ideal spinopelvic parameter for eliminating residual pain and disability in adult spinal deformity, the ideal value for DS remains unknown. METHODS: Prospectively collected registry data of 63 patients who underwent single-level L4-L5 open TLIF with sagittal realignment for DS were reviewed. Pelvic incidence, lumbar lordosis (LL), pelvic tilt, SS, listhesis excursion, and Bridwell fusion grading were recorded. Patients were stratified into SS<30 degrees (n=26) or SS≥30 degrees (n=37) at the last follow-up. All patients were assessed preoperatively and postoperatively at 2 years. Receiver operating characteristics curve analysis was used to assess the relationship between expectation fulfillment and change in SS. RESULTS: Patients with SS≥30 degrees had significantly lower back pain at 2 years (P<0.04). There were no differences in leg pain or outcome scores (Oswestry Disability Index, Short-Form 36 Physical, and Mental Component Summaries), although there was a trend towards better outcomes and higher satisfaction/expectation fulfillment in patients with SS≥30 degrees. The SS≥30 degrees group had a higher preoperative LL (P=0.04) and SS (P<0.01). Preoperative SS was correlated with SS (R=0.71, P<0.01) and LL (R=0.51, P<0.01) at the last follow-up. The area under the curve for change in SS was 0.680 (95% confidence interval, 0.453-0.907) for predicting expectation fulfillment at 2 years. CONCLUSIONS: Patients with increased SS (≥30 degrees) experienced less back pain after short-segment lumbar fusion surgery. This was associated with increased LL postoperatively, indicating better sagittal balance.

Intraoperative Motor Evoked Potential Improvement in Cervical Spondylotic Myelopathy: Comparison of Cortical Stimulation Parameters.

BACKGROUND AND PURPOSE: Intraoperative monitoring of the motor pathways is a routine procedure for ensuring the integrity of descending motor tracts during spinal surgery. Intraoperative motor evoked potential improvement (MEPI) may be associated with a better postsurgical outcome in cervical spondylotic myelopathy (CSM). To compare the efficacy of two cortical stimulation parameters in eliciting MEPI intraoperatively during CSM surgery. METHODS: We studied 69 patients who underwent decompression surgery for CSM over a 9-month period using either 5 (Group 1) or 9 (Group 2) stimuli. MEPI was defined as the increase in the amplitude of MEPs from baseline at the end of CSM surgery just prior to skin closure. RESULTS: An MEPI of 100% from baseline was observed in 10 patients (53%) in Group 1 and 36 patients (72%) in Group 2. Comparisons of the baseline mean MEP amplitudes of muscles bilaterally between Groups 1 and 2 did not reveal any significant differences. Supramaximal stimulation showed that a significantly higher mean intensity was required for Group 1 than for Group 2. CONCLUSIONS: MEPI is observed in a much larger proportion of cervical decompression surgery cases than previously thought. Intraoperative MEPI with longer-train cortical stimulation may reflect adequacy of decompression and provide additional guidance for the surgical procedure.