Impact of age on comparative outcomes of decompression alone versus fusion for L4 degenerative spondylolisthesis.

PURPOSE: To compare the outcomes of decompression alone and fusion for L4-5 DLS in different age cohorts (< 70 years, ≥ 70 years). METHODS: This retrospective cohort study included patients who underwent minimally invasive decompression or fusion for L4-5 DLS and had a minimum of 1-year follow-up. Outcome measures were: (1) patient-reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale back and leg, VAS; 12-Item Short Form Survey Physical Component Score, SF-12 PCS), (2) minimal clinically important difference (MCID), (3) patient acceptable symptom state (PASS), (4) response on the global rating change (GRC) scale, and (5) complication rates. The decompression and fusion groups were compared for outcomes separately in the < 70-year and ≥ 70-year age cohorts. RESULTS: 233 patients were included, out of which 52% were < 70 years. Patients < 70 years showed non-significant improvement in SF-12 PCS and significantly lower MCID achievement rates for VAS back after decompression compared to fusion. Analysis of the ≥ 70-year age cohort showed no significant differences between the decompression and fusion groups in the improvement in PROMs, MCID/PASS achievement rates, and responses on GRC. Patients ≥ 70 years undergoing fusion had significantly higher in-hospital complication rates. When analyzed irrespective of the surgery type, both < 70-year and ≥ 70-year age cohorts showed significant improvement in PROMs with no significant difference. CONCLUSIONS: Patients < 70 years undergoing decompression alone did not show significant improvement in physical function and had significantly less MCID achievement rate for back pain compared to fusion. Patients ≥ 70 years showed no difference in outcomes between decompression alone and fusion.

Improved 3D DESS MR neurography of the lumbosacral plexus with deep learning and geometric image combination reconstruction.

OBJECTIVE: To evaluate the impact of deep learning (DL) reconstruction in enhancing image quality and nerve conspicuity in LSP MRN using DESS sequences. Additionally, a geometric image combination (GIC) method to improve DESS signals' combination was proposed. MATERIALS AND METHODS: Adult patients undergoing 3.0 Tesla LSP MRN with DESS were prospectively enrolled. The 3D DESS echoes were separately reconstructed with and without DL and DL-GIC combined reconstructions. In a subset of patients, 3D T2-weighted short tau inversion recovery (STIR-T2w) sequences were also acquired. Three radiologists rated 4 image stacks ('DESS S2', 'DESS S2 DL', 'DESS GIC DL' and 'STIR-T2w DL') for bulk motion, vascular suppression, nerve fascicular architecture, and overall nerve conspicuity. Relative SNR, nerve-to-muscle, -fat, and -vessel contrast ratios were measured. Statistical analysis included ANOVA and Wilcoxon signed-rank tests. p < 0.05 was considered statistically significant. RESULTS: Forty patients (22 females; mean age = 48.6 ± 18.5 years) were enrolled. Quantitatively, 'DESS GIC DL' demonstrated superior relative SNR (p < 0.001), while 'DESS S2 DL' exhibited superior nerve-to-background contrast ratio (p value range: 0.002 to < 0.001). Qualitatively, DESS provided superior vascular suppression and depiction of sciatic nerve fascicular architecture but more bulk motion as compared to 'STIR-T2w DL'. 'DESS GIC DL' demonstrated better nerve visualization for several smaller, distal nerve segments than 'DESS S2 DL' and 'STIR-T2w DL'. CONCLUSION: Application of a DL reconstruction with geometric image combination in DESS MRN improves nerve conspicuity of the LSP, especially for its smaller branch nerves.

Quantifying forest resilience post forest fire disturbances using time-series satellite data.

Quantification of forest resilience will help us to manage the sustainability of the forest environment and the safety of biodiversity. Measuring forest resilience is crucial for ensuring long-term health of the forest ecosystem in the face of ongoing environmental changes and disturbances. This study focuses on providing a framework to estimate forest resilience scores to assess the vegetation condition after a disturbance. The resilience calculation framework provided uses number of recovery days, the phenological performance level of vegetation in the year when the disturbance took place, long-term mean phenological performance, and greenness levels in subsequent year to calculate the final resilience score at each pixel. Recovery of forests using Landsat data with the help of Normalized Difference Vegetation Index or Normalized Burn Ratio poses a challenge for continuous monitoring of forested landscapes due to cloud cover and availability of scenes at continuous intervals in Landsat datasets. In this regard, MODIS 16-day EVI products were used in this study (2001 to 2020) for monitoring vegetation health before, during, and after the disaster. Bandhavgarh National Park (BNP) located in Madhya Pradesh, India is considered for this study as it witnessed major forest fire breakouts in the second half of March 2018. The objectives of the study are the following: (1) to estimate post-fire recovery days and (2) to formulate new resilience index. The study revealed that the northern part of BNP is more vulnerable and shows slow recovery. The relationship between occupation of people living inside and in the neighboring area with forest resilience is also investigated in this study.

Perception of Robotics and Navigation by Spine Fellows and Early Attendings: The Impact of These Technologies on Their Training and Practice.

BACKGROUND: There is scant data on the role that robotics and navigation play in spine surgery training and practice of early attendings. This study aimed to assess the impact of navigation and robotics on spine surgery training and practice. METHODS: A survey gathering information on utilization of navigation and robotics in training and practice was administered to trainees and early attendings. RESULTS: A total of 51 surveys were returned completed: 71% were attendings (average practice years: 2), 29% were trainees. During training, 22% were exposed to only fluoroscopy, 75% were exposed to navigation, 51% were exposed to robotics, and 40% were exposed to both navigation and robotics. In our sample, 87% and 61% of respondents who had exposure to navigation and robotics, respectively, felt that it had a positive impact on their training. In practice, 28% utilized only fluoroscopy, 69% utilized navigation, 30% utilized robotics, and 28% utilized both navigation and robotics. The top 3 reasons behind positive impact on training and practice were: 1) increased screw accuracy, 2) exposure to upcoming technology, and 3) less radiation exposure. The top 3 reasons behind negative impact were: 1) compromises training to independently place screws, 2) time and personnel requirements, and 3) concerns about availing it in practice. In sum, 76% of attendings felt that they will be utilizing more navigation and robotics in 5 years' time. CONCLUSIONS: Navigation and robotics have a perceivably positive impact on training and are increasingly being incorporated into practice. However, associated concerns demand spine surgeons to be thoughtful about how they integrate these technologies moving forward.

Impact of Frailty and Cervical Radiographic Parameters on Postoperative Dysphagia Following Anterior Cervical Spine Surgery.

STUDY DESIGN: Retrospective review of a prospectively collected registry. OBJECTIVE: The purpose of the present study was to investigate the impact of frailty and radiographical parameters on postoperative dysphagia after anterior cervical spine surgery (ACSS). SUMMARY OF BACKGROUND DATA: There is a growing body of literature indicating an association between frailty and increased postoperative complications following various surgeries. However, few studies have investigated the relationship between frailty and postoperative dysphagia after anterior cervical spine surgery. MATERIALS AND METHODS: Patients who underwent anterior cervical spine surgery for the treatment of degenerative cervical pathology were included. Frailty and dysphagia were assessed by the modified Frailty Index-11 (mFI-11) and Eat Assessment Tool 10 (EAT-10), respectively. We also collected clinical demographics and cervical alignment parameters previously reported as risk factors for postoperative dysphagia. Multivariable logistic regression was performed to identify the odds ratio (OR) of postoperative dysphagia at early (2-6 weeks) and late postoperative time points (1-2 years). RESULTS: Ninety-five patients who underwent ACSS were included in the study. Postoperative dysphagia occurred in 31 patients (32.6%) at the early postoperative time point. Multivariable logistic regression identified higher mFI-11 score (OR, 4.03; 95% CI: 1.24-13.16; P =0.021), overcorrection of TS-CL after surgery (TS-CL, T1 slope minus C2-C7 lordosis; OR, 0.86; 95% CI: 0.79-0.95; P =0.003), and surgery at C3/C4 (OR, 12.38; 95% CI: 1.41-108.92; P =0.023) as factors associated with postoperative dysphagia. CONCLUSIONS: Frailty, as assessed by the mFI-11, was significantly associated with postoperative dysphagia after ACSS. Additional factors associated with postoperative dysphagia were overcorrection of TS-CL and surgery at C3/C4. These findings emphasize the importance of assessing frailty and cervical alignment in the decision-making process preceding ACSS.

Psoas Muscle Health is Correlated with Time to Achieve MCID in Patients with Predominant Axial Back Pain Following Decompression Surgery: Early Results.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine the impact of psoas muscle health (cross-sectional area, CSA) on achieving minimal clinically important differences (MCID) in patient-reported outcome measures (PROMs) following laminectomy for patients with predominant back pain (PBP) and leg pain (PLP). SUMMARY OF BACKGROUND DATA: Psoas muscle health is linked to postoperative outcomes in decompression patients, with MRI-based grading of psoas CSA correlating with these outcomes. However, evidence on its impact on symptomatic recovery, measured by PROMs, is lacking. METHODS: 106 patients with PBP (VAS back >VAS leg) and 139 patients with PLP (VAS leg >VAS back) who underwent laminectomy from 2017-2021 were included. Axial T2 MRI images were analyzed for psoas CSA using a validated method. Based on the lowest-quartile normalized total psoas area (NTPA) thresholds, patients were divided into "Good" and "Poor" muscle health groups. The correlation analyses were performed between the psoas CSA and changes in PROMs. Kaplan-Meier survival analysis was conducted to determine the probability of achieving MCID as a function of time. RESULTS: Of 106 PBP patients, 83 (78.3%) had good muscle health, 23 (21.6%) had poor muscle health. Of 139 PLP patients, 54 (38.8%) had good muscle health, 85 (61.1%) had poor muscle health. In the PBP group, older age was associated with poor muscle health (69.70±9.26 vs. 59.92±15.01, P=0.0002). For both cohorts, there were no differences in the rate of MCID achievement for any PROMs between the good and poor muscle health groups. In the PBP group, Kaplan-Meier analysis showed patients with good psoas health achieved MCID-VAS back and Oswestry Disability Index (ODI) in median times of 14 and 42 days (P=0.045 and 0.015), respectively. CONCLUSION: Good psoas muscle health is linked to faster attainment of MCID, especially in patients with PBP compared to PLP after decompression surgery. LEVEL OF EVIDENCE: 3.

Clinical and Radiological Predictors of Slower and Non-Improvement Following Surgical Treatment of L4-5 Degenerative Spondylolisthesis: Preliminary Results.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To identify the predictors of slower and non-improvement following surgical treatment of L4-5 degenerative lumbar spondylolisthesis (DLS). SUMMARY OF BACKGROUND DATA: There is limited evidence regarding clinical and radiological predictors of slower and non-improvement following surgery for L4-5 DLS. METHODS: Patients who underwent minimally invasive decompression or fusion for L4-5 DLS and had a minimum of 1-year follow-up were included. Outcome measures were: (1) minimal clinically important difference (MCID), (2) patient acceptable symptom state (PASS), and (3) global rating change (GRC). Clinical variables analyzed for predictors were age, gender, body mass index (BMI), surgery type, comorbidities, anxiety, depression, smoking, osteoporosis, and preoperative patient reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS). Radiological variables analyzed were slip percentage, translational and angular motion, facet diastasis/cyst/orientation, laterolisthesis, disc height, scoliosis, main and fractional curve Cobb angles, and spinopelvic parameters. RESULTS: 233 patients (37% decompression, 63% fusion) were included. At <3 months, high pelvic tilt (PT) (OR 0.92, P 0.02) and depression (OR 0.28, P 0.02) were predictors of MCID non-achievement and GRC non-betterment, respectively. Neither retained significance at >6 months and hence, were identified as predictors of slower improvement. At >6 months, low preoperative VAS leg (OR 1.26, P 0.01) and high facet orientation (OR 0.95, P 0.03) were predictors of MCID non-achievement, high L4-5 slip percentage (OR 0.86, P 0.03) and L5-S1 angular motion (OR 0.78, P 0.01) were predictors of GRC non-betterment, and high preoperative ODI (OR 0.96, P 0.04) was a predictor of PASS non-achievement. CONCLUSIONS: High PT and depression were predictors of slower improvement and low preoperative leg pain, high disability, high facet orientation, high slip percentage, and L5-S1 angular motion were predictors of non-improvement. However, these are preliminary findings and further studies with homogeneous cohorts are required to establish these findings.

Opening Side of Unilateral Open-Door Laminoplasty Does Not Impact Improvement in Arm Pain or Space Available for the Spinal Cord.

Background/Objectives: There exists limited data guiding open-door laminoplasty. The objective of this study is to determine if open-door laminoplasty affects radiographic decompression or arm pain outcomes. Methods: Adult patients who underwent unilateral open-door laminoplasty cervical myelopathy were included. The side opened was dependent on surgeon discretion. We recorded preoperative side of symptoms, side of radiographic compression, arm pain scores, and canal diameter. Patients with open-side ipsilateral or contralateral to dominant symptoms or compression were compared to determine any effect on arm pain outcomes or spinal canal diameter. If the symptoms were equal bilaterally, patients were neutral. Results: A total of 167 patients were included, with an average age of 64 ± 11 years and average follow-up time of 64.5 ± 72 weeks. The average preoperative arm pain visual analog score (VAS) was 2.13 ± 2.86, and the average arm VAS after 6 months was 1.52 ± 2.68. For dominant symptoms, the ipsilateral, contralateral, and neutral groups had a significant improvement in arm VAS at >6 months postoperatively. For dominant compression, the ipsilateral and contralateral groups had a significant improvement in both arm VASs and canal diameter at >6 months postoperatively. No differences were seen between groups for either. We observed a significant correlation between size of plate and change in canal diameter; however, no differences were noted for arm pain. Conclusions: Laminoplasty may be effective in addressing radicular arm pain by increasing the spinal canal's diameter and space available for the cord. The laterality of open-door laminoplasty did not affect arm pain improvement or canal expansion.

Ninety Percent of Patients Are Satisfied With Their Decision to Undergo Spine Surgery for Degenerative Conditions.

STUDY DESIGN: Cross-sectional survey and retrospective review of prospectively collected data. OBJECTIVE: To explore how patients perceive their decision to pursue spine surgery for degenerative conditions and evaluate factors correlated with decisional regret. SUMMARY OF BACKGROUND DATA: Prior research shows that one-in-five older adults regret their decision to undergo spinal deformity surgery. However, no studies have investigated decisional regret in patients with degenerative conditions. METHODS: Patients who underwent cervical or lumbar spine surgery for degenerative conditions (decompression, fusion, or disk replacement) between April 2017 and December 2020 were included. The Ottawa Decisional Regret Questionnaire was implemented to assess prevalence of decisional regret. Questionnaire scores were used to categorize patients into low (<40) or medium/high (≥40) decisional regret cohorts. Patient-reported outcome measures (PROMs) included the Oswestry Disability Index, Patient-reported Outcomes Measurement Information System, Visual Analog Scale (VAS) Back/Leg/Arm, and Neck Disability Index at preoperative, early postoperative (<6 mo), and late postoperative (≥6 mo) timepoints. Differences in demographics, operative variables, and PROMs between low and medium/high decisional regret groups were evaluated. RESULTS: A total of 295 patients were included (mean follow-up: 18.2 mo). Overall, 92% of patients agreed that having surgery was the right decision, and 90% would make the same decision again. In contrast, 6% of patients regretted the decision to undergo surgery, and 7% noted that surgery caused them harm. In-hospital complications (P=0.02) and revision fusion (P=0.026) were significantly associated with higher regret. The medium/high decisional regret group also exhibited significantly worse PROMs at long-term follow-up for all metrics except VAS-Arm, and worse achievement of minimum clinically important difference for Oswestry Disability Index (P=0.007), Patient-Reported Outcomes Measurement Information System (P<0.0001), and VAS-Leg (P<0.0001). CONCLUSIONS: Higher decisional regret was encountered in the setting of need for revision fusion, increased in-hospital complications, and worse PROMs. However, 90% of patients overall were satisfied with their decision to undergo spine surgery for degenerative conditions. Current tools for assessing patient improvement postoperatively may not adequately capture the psychosocial values and patient expectations implicated in decisional regret.

Temporal Trends of Improvement After Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To analyze temporal trends in improvement after minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). SUMMARY OF BACKGROUND DATA: Although several studies have shown that patients improve significantly after MIS TLIF, evidence regarding the temporal trends in improvement is still largely lacking. METHODS: Patients who underwent primary single-level MIS TLIF for degenerative conditions of the lumbar spine and had a minimum of 2-year follow-up were included. Outcome measures were: 1) patient reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS); 2) global rating change (GRC); 3) minimal clinically important difference (MCID); and 4) return to activities. Timepoints analyzed were preoperative, 2 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years. Trends across these timepoints were plotted on graphs. RESULTS: 236 patients were included. VAS back and VAS leg were found to have statistically significant improvement compared to the previous timepoint up to 3 months after surgery. ODI and SF-12 PCS were found to have statistically significant improvement compared to the previous timepoint up to 6 months after surgery. Beyond these timepoints, there was no significant improvement in PROMs. 80% of patients reported feeling better compared to preoperative by 3 months. >50% of patients achieved MCID in all PROMs by 3 months. Most patients returned to driving, returned to work, and discontinued narcotics at an average of 21, 20, and 10 days, respectively. CONCLUSIONS: Patients are expected to improve up to 6 months after MIS TLIF. Back pain and leg pain improve up to 3 months and disability and physical function improve up to 6 months. Beyond these timepoints, the trends in improvement tend to reach a plateau. 80% of patients feel better compared to preoperative by 3 months after surgery.

Morbidly Obese Patients Have Similar Clinical Outcomes and Recovery Kinetics After Minimally Invasive Decompression.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To study the impact of class 2/3 obesity (body mass index, BMI >35) on outcomes following minimally invasive decompression. SUMMARY OF BACKGROUND DATA: No previous study has analyzed the impact of class 2/3 obesity on outcomes following minimally invasive decompression. METHODS: Patients who underwent primary minimally invasive decompression were divided into 4 cohorts based on their BMI: normal (BMI 18.5 to <25), overweight (25 to <30), class 1 obesity (30 to <35), and class 2/3 obesity (BMI >35). Outcome measures were: 1) intraoperative variables: operative time, estimated blood loss (EBL); 2) patient reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS); 3) global rating change (GRC), minimal clinically important difference (MCID), and patient acceptable symptom state (PASS) achievement rates; 4) return to activities; and 5) complication and reoperation rates. RESULTS: 838 patients were included (226 normal, 357 overweight, 179 class 1 obesity, 76 class 2/3 obesity). Class 1 and 2/3 obesity groups had significantly greater operative times compared to the other groups. Class 2/3 obesity group had worse ODI, VAS back and SF-12 PCS preoperatively, worse ODI, VAS back, VAS leg and SF-12 PCS at <6 months, and worse ODI and SF-12 PCS at >6 months. However, they had significant improvement in all PROMs at both postoperative timepoints and the magnitude of improvement was similar to other groups. No significant differences were found in MCID and PASS achievement rates, likelihood of betterment on the GRC scale, return to activities, and complication/reoperation rates. CONCLUSIONS: Class 2/3 obese patients have worse PROMs pre- and post-operatively. However, they show similar improvement in PROMs, MCID and PASS achievement rates, likelihood of betterment, recovery kinetics, and complication/reoperation rates as other BMI groups following minimally invasive decompression.

Limited Improvement With Minimally Invasive Lumbar Decompression Alone for Degenerative Scoliosis With Cobb Angle Over 20°: The Impact of Decompression Location.

STUDY DESIGN: Retrospective review of a prospectively collected multisurgeon registry. OBJECTIVE: To evaluate the outcomes of minimally invasive (MI) decompression in patients with severe degenerative scoliosis (DS) and identify factors associated with poorer outcomes. SUMMARY OF BACKGROUND CONTEXT: MI decompression has gained widespread acceptance as a treatment option for patients with lumbar canal stenosis and DS. However, there is a lack of research regarding the clinical outcomes and the impact of MI decompression location in patients with severe DS exhibiting a Cobb angle exceeding 20°. MATERIALS AND METHODS: Patients who underwent MI decompression alone were included and categorized into the DS or control groups based on Cobb angle (>20°). Decompression location was labeled as "scoliosis-related" when the decompression levels were across or between end vertebrae and "outside" when the operative levels did not include the end vertebrae. The outcomes, including the Oswestry Disability Index (ODI), were compared between the propensity score-matched groups for improvement and minimal clinical importance difference (MCID) achievement at ≥1 year postoperatively. Multivariable regression analysis was conducted to identify factors contributing to the nonachievement of MCID in ODI of the DS group at the ≥1-year time point. RESULTS: A total of 253 patients (41 DS) were included in the study. Following matching for age, sex, osteoporosis status, psoas muscle area, and preoperative ODI, the DS groups exhibited a significantly lower rate of MCID achievement in ODI (DS: 45.5% vs. control 69.0%, P =0.047). The "scoliosis-related" decompression (odds ratio: 9.9, P =0.028) was an independent factor of nonachievement of MCID in ODI within the DS group. CONCLUSIONS: In patients with a Cobb angle >20°, lumbar decompression surgery, even in the MI approach, may result in limited improvement of disability and physical function. Caution should be exercised when determining a surgical plan, especially when decompression involves the level between or across the end vertebrae. LEVEL OF EVIDENCE: 3.

Preoperative Disability Influences Effectiveness of MCID and PASS in Predicting Patient Improvement Following Lumbar Spine Surgery.

STUDY DESIGN: Retrospective cohort. SUMMARY OF BACKGROUND DATA: Although minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) are utilized to interpret Oswestry Disability Index (ODI), it is unclear whether there is a clearly better metric between the two and if not, which metric should be utilized when. OBJECTIVE: To compare the characteristics of MCID and PASS when interpreting ODI after lumbar spine surgery. METHODS: Patients who underwent primary minimally invasive transforaminal lumbar interbody fusion or decompression were included. The ODI and global rating change data at 1 year were analyzed. The global rating change was collapsed to a dichotomous outcome variable-(a) improved, (b) not improved The sensitivity, specificity, positive predictive value and negative predictive value of MCID and PASS were calculated for the overall cohort and separately for patients with minimal, moderate, and severe preoperative disability. Two groups with patients who achieved PASS but not MCID and patients who achieved MCID but not PASS were analyzed. RESULTS: Two hundred twenty patients (mean age 62 y, 57% males) were included. PASS (86% vs. 69%) and MCID (88% vs. 63%) had significantly greater sensitivity in patients with moderate and severe preoperative disability, respectively. Nineteen percent of patients achieved PASS but not MCID and 10% of patients achieved MCID but not PASS, with the preoperative ODI being significantly greater in the latter. Most of these patients still reported improvement with no significant difference between the 2 groups (93% vs. 86%). CONCLUSION: Significant postoperative clinical improvement is most effectively assessed by PASS in patients with minimal or moderate preoperative disability and by MCID in patients with severe preoperative disability. Adequate interpretation of ODI using the PASS and MCID metrics warrants individualized application as their utility is highly dependent on the degree of preoperative disability.

Comparison of Robotics and Navigation for Clinical Outcomes After Minimally Invasive Lumbar Fusion.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To compare navigation and robotics in terms of clinical outcomes after minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). SUMMARY OF BACKGROUND DATA: Although robotics has been shown to have advantages like reduced radiation exposure, greater screw size, and slightly better accuracy over navigation, none of the studies has compared these two modalities in terms of clinical outcomes. METHODS: Patients who underwent single-level MI-TLIF using robotics or navigation and had a minimum of 1-year follow-up were included. The robotics and navigation groups were compared for improvement in patient-reported outcome measures (PROMs), minimal clinically important difference, patient-acceptable symptom state, response on the global rating change scale, and screw-related complication and reoperation rates. RESULTS: A total of 278 patients (143 robotics, 135 navigation) were included. There was no significant difference between the robotics and navigation groups in the baseline demographics, operative variables, and preoperative PROMs. Both groups showed significant improvement in PROMs at below six and six months or above, with no significant difference in the magnitude of improvement between the two groups. Most patients achieved minimal clinically important difference and patient-acceptable symptom state and reported feeling better on the global rating change scale, with no significant difference in the proportions between the robotics and navigation groups. The screw-related complication and reoperation rates also showed no significant difference between the two groups. CONCLUSIONS: Robotics did not seem to lead to significantly better clinical outcomes compared with navigation following MI-TLIF. Although the clinical outcomes may be similar, robotics offers the advantages of reduced radiation exposure, greater screw size, and slightly better accuracy over navigation. These advantages should be considered when determining the utility and cost-effectiveness of robotics in spine surgery. Larger multicenter prospective studies are required in the future to further investigate this subject.

Surgeon Experience Influences Robotics Learning Curve for Minimally Invasive Lumbar Fusion: A Cumulative Sum Analysis.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To analyze the learning curves of three spine surgeons for robotic minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). SUMMARY OF BACKGROUND DATA: Although the learning curve for robotic MI-TLIF has been described, the current evidence is of low quality with most studies being single-surgeon series. MATERIALS AND METHODS: Patients who underwent single-level MI-TLIF with three spine surgeons (years in practice: surgeon 1: 4, surgeon 2: 16, and surgeon 3: two) using a floor-mounted robot were included. Outcome measures were operative time, fluoroscopy time, intraoperative complications, screw revision, and patient-reported outcome measures. Each surgeon's cases were divided into successive groups of 10 patients and compared for differences. Linear regression and cumulative sum (CuSum) analyses were performed to analyze the trend and learning curve, respectively. RESULTS: A total of 187 patients were included (surgeon 1: 45, surgeon 2: 122, and surgeon 3: 20). For surgeon 1, CuSum analysis showed a learning curve of 21 cases with the attainment of mastery at case 31. Linear regression plots showed negative slopes for operative and fluoroscopy time. Both learning phase and postlearning phase groups showed significant improvement in patient-reported outcome measures. For surgeon 2, CuSum analysis demonstrated no discernible learning curve. There was no significant difference between successive patient groups in either operative time or fluoroscopy time. For surgeon 3, CuSum analysis demonstrated no discernible learning curve. Even though the difference between successive patient groups was not significant, cases 11 to 20 had an average operative time of 26 minutes less than cases 1-10), suggesting an ongoing learning curve. CONCLUSIONS: Surgeons who are well-experienced can be expected to have no or minimal learning curve for robotic MI-TLIF. Early attendings are likely to have a learning curve of around 21 cases with the attainment of mastery at case 31. Learning curve does not seem to impact clinical outcomes after surgery. LEVEL OF EVIDENCE: Level 3.

Provider Referral Patterns and Surgical Utilization Among New Patients Seen in Spine Clinic.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: The objective of this study was to elucidate the demographics of patient referrals from different sources and identify factors that affect a patient's likelihood of undergoing surgery. SUMMARY OF BACKGROUND DATA: Despite baseline factors for surgical consideration, such as attempting conservative management, surgeons encounter many patients who are not surgically indicated. Overreferrals, that is, a patient referred to a surgeon that does not need surgery, can result in long wait times, delayed care, worse outcomes, and resource waste. MATERIALS AND METHODS: All new patients at a single academic institution seen in the clinic by eight spine surgeons between January 1, 2018, and January 1, 2022, were analyzed. Referral types included self-referral, musculoskeletal (MSK), and non-MSK provider referral. Patient demographics included age, body mass index (BMI), zip code as a proxy for socioeconomic status, sex, insurance type, and surgical procedures undergone within 1.5 years postclinic visit. Analysis of variance and a Kruskal-Wallis test was used to compare means among normally and non-normally disturbed referral groups, respectively. Multivariable logistic regressions were run to assess demographic variables associated with undergoing surgery. RESULTS: From 9356 patients, 84% (7834) were self-referred, 3% (319) were non-MSK, and 13% (1203) were MSK. A statistically significant association with ultimately undergoing surgery was observed with MSK referral type compared with non-MSK referral [odds ratio (OR)=1.37, CI: 1.04-1.82, P =0.0246]. Additional independent variables observed to be associated with patients undergoing surgery included older age (OR=1.004, CI: 1.002-1.007, P =0.0018), higher BMI (OR=1.02, CI: 1.011-1.029, P <0.0001), high-income quartile (OR=1.343, CI: 1.177-1.533, P <0.0001), and male sex (OR=1.189, CI: 1.085-1.302, P =0.0002). CONCLUSIONS: A statistically significant association with undergoing surgery was observed with a referral by an MSK provider, older age, male sex, high BMI, and a high-income quartile home zip code. Understanding these factors and patterns is critical for optimizing practice efficiency and reducing the burdens of inappropriate referrals.

Poor muscle health and low preoperative ODI are independent predictors for slower achievement of MCID after minimally invasive decompression.

BACKGROUND CONTEXT: Although some previous studies have analyzed predictors of nonimprovement, most of these have focused on demographic and clinical variables and have not accounted for radiological predictors. In addition, while several studies have examined the degree of improvement after decompression, there is less data on the rate of improvement. PURPOSE: To identify the risk factors and predictors (both radiological and nonradiological) for slower as well as nonachievement of minimal clinically important difference (MCID) after minimally invasive decompression. DESIGN: Retrospective cohort. PATIENT SAMPLE: Patients who underwent minimally invasive decompression for degenerative lumbar spine conditions and had a minimum of 1-year follow up were included. Patients with preoperative Oswestry Disability Index (ODI) <20 were excluded. OUTCOME MEASURE: MCID achievement in ODI (cut off 12.8). METHODS: Patients were stratified into two groups (achieved MCID, did not achieve MCID) at two timepoints (early ≤3 months, late ≥6 months). Nonradiological (age, gender, BMI, comorbidities, anxiety, depression, number of levels operated, preoperative ODI, preoperative back pain) and radiological (MRI - Schizas grading for stenosis, dural sac cross-sectional area, Pfirrmann grading for disc degeneration, psoas cross-sectional area and Goutallier grading, facet cyst/effusion; X-ray - spondylolisthesis, lumbar lordosis, spinopelvic parameters) variables were assessed with comparative analysis to identify risk factors and with multiple regression models to identify predictors for slower achievement of MCID (MCID not achieved by ≤3 months) and nonachievement of MCID (MCID not achieved at ≥6 months). RESULTS: A total of 338 patients were included. At ≤3 months, patients who did not achieve MCID had significantly lower preoperative ODI (40.1 vs 48.1, p<0.001) and worse psoas Goutallier grading (p=.048). At ≥6 months, patients who did not achieve MCID had significantly lower preoperative ODI (38 vs 47.5, p<.001), higher age (68 vs 63 years, p=.007), worse average L1-S1 Pfirrmann grading (3.5 vs 3.2, p=.035), and higher rate of pre-existing spondylolisthesis at the operated level (p=.047). When these and other probable risk factors were put into a regression model, low preoperative ODI (p=.002) and poor Goutallier grading (p=.042) at the early timepoint and low preoperative ODI (p<.001) at the late timepoint came out as independent predictors for MCID nonachievement. CONCLUSION: After minimally invasive decompression, low preoperative ODI and poor muscle health are risk factors and predictors for slower achievement of MCID. For nonachievement of MCID, low preoperative ODI, higher age, greater disc degeneration, and spondylolisthesis are risk factors and low preoperative ODI is the only independent predictor.

Preoperative Disability Influences Effectiveness of Minimal Clinically Important Difference and Patient Acceptable Symptom State in Predicting Patient Improvement Following Cervical Spine Surgery.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To compare the characteristics of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) metrics when interpreting Neck Disability Index (NDI) following cervical spine surgery. METHODS: Patients who underwent primary cervical fusion, discectomy, or laminectomy were included. NDI and global rating change (GRC) data at 6 months/1 year/2 years were analyzed. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MCID and PASS in predicting improvement on GRC were calculated for the overall cohort and separately for patients with minimal (NDI <30), moderate (NDI 30 - 49), and severe (NDI ≥ 50) preoperative disability. Two groups with patients who achieved PASS but not MCID and patients who achieved MCID but not PASS were analyzed. RESULTS: 141 patients (206 responses) were included. PASS had significantly greater sensitivity for the overall cohort (85% vs 73% with MCID, P = .02) and patients with minimal disability (96% vs 53% with MCID, P < .001). MCID had greater sensitivity for patients with severe disability (78% vs 57% with PASS, P = .05). Sensitivity was not significantly different for PASS and MCID in patients with moderate preoperative disability (83% vs 92%, P = .1). 17% of patients achieved PASS but not MCID and 9% of patients achieved MCID but not PASS. Most of these patients still reported improvement with no significant difference between the 2 groups (89% vs 72%, P = .13). CONCLUSION: PASS and MCID are better metrics for patients with minimal and severe preoperative disability, respectively. Both metrics are equally effective for patients with moderate preoperative disability.

Percutaneous Transforaminal Endoscopic Discectomy Learning Curve: A CuSum Analysis.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To describe the learning curve for percutaneous transforaminal endoscopic discectomy (PTED) and demonstrate its efficacy in treating lumbar disc herniation. SUMMARY OF BACKGROUND DATA: The learning curve for PTED has not yet been standardized in the literature. PATIENTS AND METHODS: Consecutive patients who underwent lumbar PTED by a single surgeon between December 2020 and 2022 were included. Cumulative sum analysis was applied to operative and fluoroscopy time to assess the learning curve. Inflection points were used to divide cases into early and late phases. The 2 phases were analyzed for differences in operative and fluoroscopy time, length of stay, complications, and patient-reported outcome measures (PROMs). Patient characteristics and operative levels were also compared. PROMs entailed the Oswestry Disability Index, Patient-Reported Outcomes Measurement Information System, Visual Analog Scale Back/Leg, and 12-item Short Form Survey at preoperative, early postoperative (<6 mo), and late postoperative (≥6 mo) time points. PROMs between PTED cases and a comparable cohort of tubular microdiscectomy cases, performed by the same surgeon, were compared. RESULTS: Fifty-five patients were included. Cumulative sum analysis indicated that both operative and fluoroscopy time diminished rapidly after case 31, suggesting a learning curve of 31 cases (early phase: n = 31; late phase: n = 24). Late-phase cases exhibited significantly lower operative times (85.7 vs . 62.2 min, P = 0.001) and fluoroscopy times (131.0 vs . 97.2 s, P = 0.001) compared with the early-phase cases. Both early and late-phase cases showed significant improvement in all PROMs. There were no differences in PROMs between the patients who underwent PTED and tubular microdiscectomy. CONCLUSION: The PTED learning curve was found to be 31 cases and did not impact PROMs or complication rates. Although this learning curve reflects the experiences of a single surgeon and may not be broadly applicable, PTED can serve as an effective modality for the treatment of lumbar disc herniation.

Preoperative and Postoperative Segmental and Overall Range of Motion in Patients Undergoing Lumbar Spinal Fusion Using HA-Infused PEEK and HA-Treated Titanium Alloy Interbody Cages.

STUDY DESIGN: Retrospective observational radiographic analysis. OBJECTIVE: Determine how single level lumbar interbody fusion (LIF) alters segmental range of motion (ROM) at adjacent levels and decreases overall ROM. METHODS: This study included 54 patients who underwent single-level anterior (ALIF, 39%), thoraco-LIF (TLIF, 26%), posterior LIF (PLIF, 22%), or lateral LIF (LLIF, 13%) (L2-3/L3-4/L4-5/L5-S1: 4%/13%/35%/48%). Segmental ROM from L1-2 to L5-S1 and the overall lumbar ROM (L1-S1) were assessed from preoperative and postoperative flexion-extension radiographs. K-means cluster analysis was used to identify ROM subgroups. RESULTS: The overall L1-S1 ROM decreased 14% (25.5 ± 20.4° to 22.0 ± 17.2°, P = .104) postoperatively. ROM at the fusion level decreased 77% (4.8 ± 5.0° to 1.1 ± 1.1°, P < .001). Caudal adjacent segment ROM decreased 12% (5.2 ± 5.7° to 4.6 ± 4.4°, P = .345) and cranially ROM increased 34% (4.3 ± 5.0° to 5.7 ± 5.7°, P = .05). K-cluster analysis identified 3 distinct clusters (P < .05). Cluster 1 lost more ROM and had less improvement in patient-reported outcomes measures (PROMs) than average. Cluster 2 had less ROM loss than average with worse PROMs improvement. Cluster 3 did not have changes in ROM and better improvement in PROMs than average. Successful fusion was verified in 96% of all instrumented segments with >6 months follow-up (ROM <4°). CONCLUSION: Following single-level L IF, patients should expect a loss of 3.3°, or 14% of overall lumbar motion with increases in ROM of the cranial segment. However, specific clusters of patients exist that experience different relative changes in ROM and PROMs.