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.

Differences in imaging and clinical characteristics are associated with higher rates of decompression-fusion versus decompression-alone in women compared to men for lumbar degenerative spondylolisthesis.

PURPOSE: The goals were to ascertain if differences in imaging/clinical characteristics between women and men were associated with differences in fusion for lumbar degenerative spondylolisthesis. METHODS: Patients had preoperative standing radiographs, CT scans, and intraoperative fluoroscopic images. Symptoms and comorbidity were obtained from patients; procedure (fusion-surgery or decompression-alone) was obtained from intraoperative records. With fusion surgery as the dependent variable, men and women were compared in multivariable logistic regression models with clinical/imaging characteristics as independent variables. The sample was dichotomized, and analyses were repeated with separate models for men and women. RESULTS: For 380 patients (mean age 67, 61% women), women had greater translation, listhesis angle, lordosis, and pelvic incidence, and less diastasis and disc height (all p ≤ 0.03). The rate of fusion was higher for women (78% vs. 65%; OR 1.9, p = 0.008). Clinical/imaging variables were associated with fusion in separate models for men and women. Among women, in the final multivariable model, less comorbidity (OR 0.5, p = 0.05), greater diastasis (OR 1.6, p = 0.03), and less anterior disc height (OR 0.8, p = 0.0007) were associated with fusion. Among men, in the final multivariable model, opioid use (OR 4.1, p = 0.02), greater translation (OR 1.4, p = 0.0003), and greater diastasis (OR 2.4, p = 0.0002) were associated with fusion. CONCLUSIONS: There were differences in imaging characteristics between men and women, and women were more likely to undergo fusion. Differences in fusion within groups indicate that decisions for fusion were based on composite assessments of clinical and imaging characteristics that varied between men and women.

The association between pain scores and disc height change following discectomy surgery in lumbar disc herniation patients: a systematic review and meta-analysis.

PURPOSE: To evaluate the impact of discectomy on disc height (DH) in lumbar disc herniation (LDH) patients following discectomy surgery and address the association of DH change with pain score change. METHODS: We searched three online databases for randomized controlled trials (RCTs) and observational studies. In LDH patients, eligible for discectomy surgery, the changes in pre- and post-operative back and/or leg pain score and DH and/or disc height index (DHI) were considered as primary outcomes. Standardize mean difference (SMD) and their 95% confidence intervals (CI) were evaluated. The GRADE approach was used to summarize the strength of evidence. RESULTS: Two RCTs and sixteen observational studies were included in the analysis of 893 LDH patients undergoing discectomy surgery. The mean overall follow-up was 211 weeks. There was a statistically significant reduction in DH (14.4% reduction: SMD = -0.74 (95% CI = -0.86 to -0.61)) and DHI (11.5% reduction: SMD = -0.81 (95% CI = -0.97 to -0.65)) following discectomy surgery. There was a significant relationship between the reduction in DH and decrease in back pain score (r = 0.68, (95% CI = 0.07-1.30), p = 0.034) after discectomy surgery. No significant relationship between DHI change and decrease in clinical pain scores (back and leg pain) could be established. CONCLUSION: Discectomy surgery produces significant and quantifiable reductions in DH and DHI. Additionally, the reduction in DH is responsible for the decrease in back pain scores post discectomy, but further studies will improve understanding and aid preoperative counselling.

What is the Rate of Revision Discectomies After Primary Discectomy on a National Scale?

BACKGROUND: Lumbar discectomy has been shown to be clinically beneficial in numerous studies for appropriately selected patients. Some patients, however, undergo revision discectomy, with previously reported estimates of revisions ranging from 5.1% to 7.9%. No study to date has been able to precisely quantify the rate of revision surgery over numerous years on a national scale. QUESTIONS/PURPOSE: We performed a survival analysis for lumbar discectomy on a national scale using a life-table analysis to answer the following questions: (1) What is the rate of revision discectomy on a national scale over 5 to 7 years for patients undergoing primary discectomy alone? (2) Are there differences in revision discectomy rates based on age of patient, region of the country, or the payer type? METHODS: The Medicare 5% National Sample Administrative Database (SAF5) and a large national database from Humana Inc (HORTHO) were used to catalog the number of patients undergoing a lumbar discectomy. Both of these databases have been cited in numerous peer-reviewed publications during the previous 5 years and routinely are audited by PearlDiver Inc. We identified patients using relevant ICD-9 codes and Current Procedural Terminology (CPT) codes, including ICD-9 72210 (lumbar disc displacement) for disc herniation. We used appropriate CPT codes to identify patients who had a lumbar discectomy. We analyzed patients undergoing additional surgery including those who had repeat discectomy (CPT-63042: laminotomy, reexploration single interspace, lumbar) and patients who had additional more-extensive decompressive procedures with or without fusion after their primary procedure. Revision surgery rates were calculated for patients 65 years and older and those younger than 65 years and for each database (Humana Inc and Medicare). Patients from the two databases also were analyzed based on four distinct geographic regions in the United States where their surgery occurred. There were a total of 7520 patients who underwent a lumbar discectomy for an intervertebral disc displacement with at least 5 years of followup in the HORTHO and SAF5 databases. We used cumulative incidence of revision surgery to estimate the survivorship of these patients. RESULTS: In the HORTHO (2613 patients) and SAF5 (4907 patients) databases, 147 patients (5.6%; 95% CI, 1.8%-9.2%) and 305 patients (6.2%; 95% CI, 3.5%-8.9%) had revision surgery at 7 years after the index discectomy respectively. Survival analysis showed survival rates greater than 93% (95% CI, 91%-98%) for all of the cohorts for a primary discectomy up to 7 years after the surgery. The survivorship was lower for patients younger than 65 years (93% [95% CI, 87%-99%, 1016 of 1091] versus 95% [95% CI, 90%-100%, 1450 of 1522], p = 0.02). When nondiscectomy lumbar surgeries were included, the survivorship of patients younger than 65 years remained lower (83% [95% CI, 76%-89%, 902 of 1091] versus 87% [95% CI, 82%-92%, 1324 of 1522], p = 0.02). There was no difference in revision discectomy rates across geographic regions (p = 0.41) at 7 years. Similarly, there was no difference in additional nondiscectomy lumbar surgery rates (p = 0.68) across geographic regions at 7 years. There was no difference in survivorship rates between patients covered by Medicare (94% [95% CI, 91%-97%], 4602 of 4907) versus Humana Inc (94% [95% CI, 90%-98%], 2466 of 2613) (p = 0.31). CONCLUSIONS: Our study shows rates of cumulative survival after an index lumbar discectomy with revision discectomy as the endpoint. We hope these data allow physicians to offer accurate advice to patients regarding the risk of revision surgery for patients of all ages during 5 to 7 years after their index procedure to enhance shared decision making in spinal surgery. These data also will help public policymakers and accountable care organizations accurately allocate scarce resources to patients with symptomatic lumbar disc herniation. LEVEL OF EVIDENCE: Level III, therapeutic study.

The use of local vancomycin powder in degenerative spine surgery.

PURPOSE: Wound infection after spine surgery is a debilitating complication. Local placement of vancomycin powder into the surgical wounds prior to closing of the fascia has been introduced as a method to reduce deep infection rates. METHODS: The infection rates of all the patients who were treated with intra-operative local vancomycin between June 2012 and June 2013 were compared to all cases that were not treated with vancomycin between January 2009 and December 2010. Patients for both groups were operated by four senior, fellowship-trained spine surgeons with a combined experience of 55 years of practice at a referral orthopedic center. Patients' charts and microbiology reports were reviewed. RESULTS: 1224 cases were performed with the use of vancomycin. The average age was 56.3 years (SD -13.2; NS). The male to female ratio was 1:1.12 (NS). 2253 cases were performed without the use of vancomycin. The average patient age was 57.1 years (SD 14.5). The male to female ratio was 1:1.14. There were 30 cases of deep infections needing a surgical irrigation and debridement without vancomycin versus 5 when vancomycin was used (P = 0.04). Infections in patients treated with vancomycin were not vancomycin-resistant bacteria. CONCLUSION: In conclusion, the use of vancomycin reduces the rate of deep wound infections and irrigation and debridement procedures after spine surgery in a referral center among surgeons with a high surgical volume.

The Cost Effectiveness of Polyetheretheketone (PEEK) Cages for Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Cost-effectiveness analysis using a Markov model with inputs from published literature. OBJECTIVE: To learn which graft or hardware option used in a single-level anterior cervical discectomy and fusion (ACDF) is most beneficial in terms of cost, quality of life, and overall cost effectiveness. Options studied were autograft, allograft, and polyetheretherketone (PEEK) cages for cervical fusion. SUMMARY OF BACKGROUND DATA: ACDF is commonly used to treat cervical myelopathy and/or radiculopathy. No study has compared the cost effectiveness of autograft, allograft, and PEEK in 1-level ACDF. MATERIALS AND METHODS: A literature review provided inputs into a Markov decision model to determine the most effective graft or hardware option for 1-level ACDF. Data regarding rate of complications, quality-adjusted life years (QALYs) gained, and cost for each procedure type was collected. The Markov model was first run in a base case, using all currently available data. The model was then tested using 1-way and 2-way sensitivity analyses to determine the validity of the model's conclusions if specific aspects of model were changed. This model was run for 10 years postoperatively. RESULTS: The cost per QALY for each option in the base case analysis was $3328/QALY for PEEK, $2492/QALY for autograft, and $2492/QALY for allograft. All graft/hardware options are cost effective ways to improve outcomes for patients living with chronic neck pain. For graft/hardware options the most cost-effective option was allograft. The incremental cost-effectiveness ratio for PEEK compared with autograft or allograft was >$100,000/QALY. CONCLUSIONS: Allograft is the most cost-effective graft/hardware option for ACDF. Compared with living with cervical myelopathy and/or radiculopathy, ACDF using any graft or hardware option is a cost-effective method of improving the quality of life of patients. PEEK is not a cost-effective option compared with allograft or autograft for use in ACDF.

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.

Intravenous Ketorolac Substantially Reduces Opioid Use and Length of Stay After Lumbar Fusion: A Randomized Controlled Trial.

STUDY DESIGN: A randomized, double-blinded, placebo-controlled trial. OBJECTIVE: To examine the effect of intravenous ketorolac (IV-K) on hospital opioid use compared with IV-placebo (IV-P) and IV acetaminophen (IV-A). SUMMARY OF BACKGROUND DATA: Controlling postoperative pain while minimizing opioid use after lumbar spinal fusion is an important area of study. PATIENTS AND METHODS: Patients aged 18 to 75 years undergoing 1 to 2 level lumbar fusions between April 2016 and December 2019 were included. Patients with chronic opioid use, smokers, and those on systemic glucocorticoids or contraindications to study medications were excluded. A block randomization scheme was used, and study personnel, hospital staff, and subjects were blinded to the assignment. Patients were randomized postoperatively. The IV-K group received 15 mg (age > 65) or 30 mg (age < 65) every six hours (q6h) for 48 hours, IV-A received 1000 mg q6h, and IV-P received normal saline q6h for 48 hours. Demographic and surgical details, opioid use in morphine milliequivalents, opioid-related adverse events, and length of stay (LOS) were recorded. The primary outcome was in-hospital opioid use up to 72 hours. RESULTS: A total of 171 patients were included (58 IV-K, 55 IV-A, and 58 IV-P) in the intent-to-treat (ITT) analysis, with a mean age of 57.1 years. The IV-K group had lower opioid use at 72 hours (173 ± 157 mg) versus IV-A (255 ± 179 mg) and IV-P (299 ± 179 mg; P = 0.000). In terms of opiate use, IV-K was superior to IV-A ( P = 0.025) and IV-P ( P = 0.000) on ITT analysis, although on per-protocol analysis, the difference with IV-A did not reach significance ( P = 0.063). When compared with IV-P, IV-K patients reported significantly lower worst ( P = 0.004), best ( P = 0.001), average ( P = 0.001), and current pain ( P = 0.002) on postoperative day 1, and significantly shorter LOS ( P = 0.009) on ITT analysis. There were no differences in opioid-related adverse events, drain output, clinical outcomes, transfusion rates, or fusion rates. CONCLUSIONS: By reducing opioid use, improving pain control on postoperative day 1, and decreasing LOS without increases in complications or pseudarthrosis, IV-K may be an important component of "enhanced recovery after surgery" protocols.

Pilot Study on Percutaneous Delivery of Recombinant Human Bone Morphongenetic Protein-2 Augments Fusion in a Nicotine-impaired Rabbit Fusion Model.

STUDY DESIGN: A nicotine-impaired spinal fusion rabbit model. OBJECTIVE: To examine whether controlled delivery of morselized absorbable collagen sponge recombinant human bone morphogenetic protein-2 (rhBMP2) in a delayed manner postsurgery would allow for improved bone healing. SUMMARY OF BACKGROUND DATA: The current delivery method of rhBMP-2 during surgery causes a burst of rhBMP-2, which is not sustained. Given that bone morphogenetic protein 2 (BMP-2) expression peaks later in the fusion process, there may be the benefit of delivery of rhBMP-2 later in the healing process. METHODS: Sixteen male 1-year-old rabbits underwent a posterolateral spinal fusion with iliac crest bone graft at L5-L6 while being given nicotine to prevent spinal fusion as previously published. Eight were controls, whereas 8 had morselized rhBMP-2 (4.2 mg) injected at the fusion site at 4 weeks postoperatively. Histologic, radiologic, and palpation examinations were performed at 12 weeks to determine fusion status and the volume of bone formed. Hematoxylin and eosin stains were used for histology. A Student t test was used to compare the computed tomography scan measured volume of bone created between the control cohort (CC) and rhBMP-2 delayed delivery cohort (BMP-DDC). RESULTS: Of the total, 7/8 rabbits in the BMP-DDC and 5/8 rabbits in the CC formed definitive fusion with a positive palpation examination, bridging bone between transverse processes on computed tomography scan, and an x-ray showing fusion. Histologic analysis revealed newly remodeled bone within the BMP-DDC. There was an increased average volume of bone formed within the BMP-DDC versus the CC (22.6 ± 13.1 vs 11.1 ± 3.6 cm 3 , P = 0.04). CONCLUSION: Our study shows that injectable morselized absorbable collagen sponge/rhBMP-2 can create twice as much bone within a nicotine-impaired rabbit spine fusion model when delivered 4 weeks out from the time of surgery.

Instability Missed by Flexion-Extension Radiographs Subsequently Identified by Alternate Imaging in L4-L5 Lumbar Degenerative Spondylolisthesis.

STUDY DESIGN: Cross-sectional preoperative and intraoperative imaging study of L4-L5 lumbar degenerative spondylolisthesis (LDS). OBJECTIVE: To determine if alternate imaging modalities would identify LDS instability that did not meet the criteria for instability based on comparison of flexion and extension radiographs. SUMMARY OF BACKGROUND DATA: Pain may limit full flexion and extension maneuvers and thereby lead to underreporting of true dynamic translation and angulation in LDS. Alternate imaging pairs may identify instability missed by flexion-extension. MATERIALS AND METHODS: Consecutive patients scheduled for surgery for single-level L4-L5 LDS had preoperative standing radiographs in the lateral, flexion, and extension positions, supine computed tomography (CT) scans, and intraoperative fluoroscopic images in the supine and prone positions after anesthesia but before incision. Instability was defined as translation ≥3.5 mm or angulation ≥11° between the following pairs of images: (1) flexion-extension; (2) CT-lateral; (3) lateral-intraoperative supine; (4) lateral-intraoperative prone; and (5) intraoperative supine-prone. RESULTS: Of 240 patients (mean age 68 y, 54% women) 15 (6%) met the criteria for instability by flexion-extension, and 225 were classified as stable. Of these 225, another 84 patients (35% of total enrollment) were reclassified as unstable by comparison of CT-lateral images (21 patients) and by lateral-intraoperative images (63 patients). Nine of the 15 patients diagnosed with instability by flexion-extension had fusion (60%), and 68 of the 84 patients reclassified as unstable by other imaging pairs had fusion (81%) ( P =0.07). The 84 reclassified patients were more likely to undergo fusion compared with the 141 patients who persistently remained classified as stable (odds ratio=2.6, 95% CI: 1.4-4.9, P =0.004). CONCLUSIONS: Our study provides evidence that flexion and extension radiographs underreport the dynamic extent of LDS and therefore should not be solely relied upon to ascertain instability. These findings have implications for how instability should be established and the extent of surgery that is indicated.

Emerging Need for PROMs to Measure the Impact of Spine Disorders on Overall Health and Well-being: Measuring Expectations as an Example for Lumbar Degenerative Spondylolisthesis.

Background: Assessing the impact of spine disorders such as lumbar degenerative spondylolisthesis (LDS) on overall health is a component of quality of care that may not be comprehensively captured by spine-specific and single-attribute patient-reported outcome measures (PROMs). Purpose: We sought to compare PROMs to the Lumbar Surgery Expectations Survey ("Expectations Survey"), which addresses multiple aspects of health and well-being, and to compare the relevance of surgeon-selected versus survey-selected Patient-Reported Outcomes Measurement Information System (PROMIS) items to LDS. Methods: In a cross-sectional study, 379 patients with LDS preoperatively completed the Expectations Survey, Numerical Rating Pain Scales, Oswestry Disability Index (ODI), and PROMIS computer-adaptive physical function, pain, and mental health surveys. Expectations Survey scores were compared to PROMs with correlation coefficients (indicating strengths of relationships) and probability values (indicating associations by chance). Surgeons reviewed physical function questions to identify those particularly relevant to LDS. Results: Patients' mean age was 67 years, 64% were women, and 83% had single-level and 17% had multiple-level LDS. Probability values between the Expectations Survey and PROMs were reliable, but strengths of relationships were only mild to moderate, indicating PROMs did not comprehensively capture the impact of LDS. None of the surgeon-selected PROMIS physical function questions were posed to patients. Conclusion: This cross-sectional study found PROMs to be reliably associated but not strongly correlated with the Expectations Survey, which addresses the whole-patient impact of LDS. New measures that complement PROMIS and ODI should be developed to capture the whole-person effects of LDS and permit attribution of LDS treatments to overall health.

Identification of Novel Genetic Markers for the Risk of Spinal Pathologies: A Genome-Wide Association Study of 2 Biobanks.

BACKGROUND: Identifying genetic risk factors for spinal disorders may lead to knowledge regarding underlying molecular mechanisms and the development of new treatments. METHODS: Cases of lumbar spondylolisthesis, spinal stenosis, degenerative disc disease, and pseudarthrosis after spinal fusion were identified from the UK Biobank. Controls were patients without the diagnosis. Whole-genome regressions were used to test for genetic variants potentially implicated in the occurrence of each phenotype. External validation was performed in FinnGen. RESULTS: A total of 389,413 participants were identified from the UK Biobank. A locus on chromosome 2 spanning GFPT1, NFU1, AAK1, and LOC124906020 was implicated in lumbar spondylolisthesis. Two loci on chromosomes 2 and 12 spanning genes GFPT1, NFU1, and PDE3A were implicated in spinal stenosis. Three loci on chromosomes 6, 10, and 15 spanning genes CHST3, LOC102723493, and SMAD3 were implicated in degenerative disc disease. Finally, 2 novel loci on chromosomes 5 and 9, with the latter corresponding to the LOC105376270 gene, were implicated in pseudarthrosis. Some of these variants associated with spinal stenosis and degenerative disc disease were also replicated in FinnGen. CONCLUSIONS: This study revealed nucleotide variations in select genetic loci that were potentially implicated in 4 different spinal pathologies, providing potential insights into the pathological mechanisms. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Phase 1 evaluation of an elastomeric nucleus pulposus device as an option to augment disc at microdiscectomy: Experimental results from biomechanical and biocompatibility testing and first in human.

Objective: Whilst microdiscectomy is an excellent reliever of pain for recalcitrant lumbar disc herniation (LDH), it has a high failure rate over time due to the ensuing reduction in mechanical stabilization and support of the spine. One option is to clear the disc and replace it with a nonhygroscopic elastomer. Here, we present the evaluation of biomechanical and biological behavior of a novel elastomeric nucleus device (Kunovus disc device [KDD]), consisting of a silicone jacket and a two-part in situ curing silicone polymer filler. Materials and Methods: ISO 10993 and American Society for Testing and Materials (ASTM) standards were used to evaluate the biocompatibility and mechanics of KDD. Sensitization, intracutaneous reactivity, acute systemic toxicity, genotoxicity, muscle implantation study, direct contact matrix toxicity assay, and cell growth inhibition assay were performed. Fatigue test, static compression creep testing, expulsion testing, swell testing, shock testing, and aged fatigue testing were conducted to characterize the mechanical and wear behavior of the device. Cadaveric studies to develop a surgical manual and evaluate feasibility were conducted. Finally, a first-in-human implantation was conducted to complete the proof of principle. Results: The KDD demonstrated exceptional biocompatibility and biodurability. Mechanical tests showed no Barium-containing particles in fatigue test, no fracture of nucleus in static compression creep testing, no extrusion and swelling, and no material failure in shock and aged fatigue testing. Cadaver training sessions showed that KDD was deemed implantable during microdiscectomy procedures in a minimally invasive manner. Following IRB approval, the first implantation in a human showed no intraoperative vascular and neurological complications and demonstrated feasibility. This successfully completed Phase 1 development of the device. Conclusion: The elastomeric nucleus device may mimic native disc behavior in mechanical tests, offering an effective way for treating LDH by way of Phase 2 and subsequent clinical trials or postmarket surveillance in the future.

Cost effectiveness analysis of graft options in spinal fusion surgery using a Markov model.

STUDY DESIGN: Statistical decision model. OBJECTIVE: To determine the most cost-effective graft option in spinal fusion. SUMMARY OF BACKGROUND DATA: Spinal fusion has been shown to be an effective technique to treat lumbar degenerative spondylolisthesis. There have been significant advances in bone graft options to improve outcomes related to spinal fusion. RhBMP-2 (RhBMP), iliac crest bone graft (ICBG), local bone alone (LBG), demineralized bone matrix with local bone (DBM), local bone with corticocancellous allograft chips (CCA) have all been used as graft options. There has not been significant research in which graft option is most cost effective. METHODS: A Markov decision model has been created to identify the most cost-effective graft option for use in spinal fusion to treat 1-level (L4-L5) degenerative spondylolisthesis in a cohort of 60-year-old patients. Costs and effectiveness of successful spinal fusion surgery and revision surgery associated with each graft option was estimated through published data. The quality adjusted life years (QALYs) from these surgeries were compared with the amount of QALYs associated with living with chronic back pain. RESULTS: : In the base case, the incremental cost-effective ratio for each graft option when compared with living with chronic back pain was $21,308/QALY for ICBG, $16,595/QALY for RhBMP, $21,204/QALY for LBG, $21,287/QALY for DBM, and $28,153/QALY for CCA. Therefore, the most cost-effective graft option in the base case was RhBMP. Sensitivity analysis shows that RhBMP is not the most cost-effective option if the revision rate is significantly raised. If the cost of treatment with RhBMP rises >$42,250 then LBG becomes the likely cost-effective treatment. CONCLUSIONS: RhBMP is the most cost-effective graft option for L4-L5 fusion for degenerative spondylolisthesis largely due to the reduced rate of revision spine surgery. The increased upfront cost and list of complications associated with RhBMP is offset by the reduced rate of revision surgery.

Radiographic evaluation of lumbar intervertebral disc height index: An intra and inter-rater agreement and reliability study.

PURPOSE: To evaluate intra- and inter-rater agreement and reliability of seven reported disc height index (DHI) measurement methods on standing lateral X-ray of lumbar spine. METHODS: The adult patients who had standing lateral X-ray of lumbar spine were recruited. Seven methods were used to measure DHI of each lumbar intervertebral disc level, including a ratio of sum of anterior and posterior disc height (DH) to disc diameter (Method 1), a ratio of middle DH to mid-vertebral body height (Method 2), a ratio of middle DH to disc diameter (Method 3), a ratio of the mean of anterior, middle, and posterior DH to the sagittal diameter of the proximal vertebral body (Method 4), a ratio of DH to vertebral height which cross the centre of adjacent vertebral bodies (Method 5), a ratio of the mean of anterior, middle, and posterior DH to the mean of proximal and distal vertebral body height (Method 6), and a ratio of the sum of anterior and posterior DH to the sum of superior and inferior disc depth (Method 7). Two raters conducted the measurements (one medical student (SS) and the other an experienced spine surgeon (XC)). Bland and Altmans Limits of Agreement (LOA) with standard difference were calculated to examine intra- and inter-rater agreements between two out of seven methods for DHI. Intra-class correlations (ICC) with 95% confidence intervals were calculated to assess intra- and inter-rater reliability. RESULTS: The intra-rater reliability in DHI measurements for 288 participants were ICCs from 0.807 (0.794, 0.812) to 0.922 (0.913, 0.946) by rater 1 (SS) and from 0.827 (0.802, 0.841) to 0.918 (0.806, 0.823) by rater 2 (XC). Method 2, 3, and 5 on all segmental levels had bias (95 % CI does not include zero) or/and out of the acceptable cut-off proportion (>50 %). A total of 609 outliers in 9174 segmental levels' LOA range. Inter-rater reliability was good-to-excellent in all but method 2 (0.736 (0.712, 0.759)) and method 5 (0.634 (0.598, 0.667)). ICCs of related lines to good-to-excellent reliability methods was excellent in all but only indirect lines in method 1 and 4 (ICCs lie in the range from 0.8 to 0.9). CONCLUSION: Following a structured protocol, intra- and inter-rater reliability was good-to-excellent for most DHI measurement methods on X-ray. However, the complicated methods (more indirect lines) and IVD degeneration (nucleus pulposus degeneration and disc herniation) potentially affected the agreement on inter-rater measurements. Method 7 is the best reproducible method to measure disc height index for all intervertebral disc segmental levels with a good-to-excellent intra- and inter-rater reliability and agreement.

Telemedicine Visits Can Generate Highly Accurate Diagnoses and Surgical Plans for Spine Patients.

STUDY DESIGN: A Retrospective cohort study. OBJECTIVE: To (1) assess whether diagnoses and surgical plans established during a new patient telemedicine visit changed following an in-person evaluation and (2) determine any differences in perioperative outcomes between patients who only had a telemedicine visit before surgery versus those who had a telemedicine visit followed by an in-person evaluation before surgery. SUMMARY OF BACKGROUND DATA: Data on capability of telemedicine to deliver high-quality preoperative assessment without a traditional in-person interaction and physical examination is lacking. MATERIALS AND METHODS: Records of patients who had a new patient telemedicine visit and indicated for surgery with documented specific diagnosis as well as surgical plans from a spine department at an urban tertiary center from April 2020 to April 2021 were reviewed. For a subset of patients that had a follow-up in-person evaluation before surgery, these diagnoses and plans were compared. Perioperative outcomes were compared between patients who only had a telemedicine visit before surgery versus those who had a telemedicine visit followed by an in-person evaluation before surgery. RESULTS: A total of 166 patients were included. Of these, 101 patients (61%) only had a new patient telemedicine visit before surgery while 65 (39%) had a telemedicine visit followed by an in-person evaluation. There were no differences in the rate of case cancellations before surgery and patient-reported outcome measures between these two groups ( P >0.05). Of 65 patients who had both a telemedicine followed by an in-person visit, the diagnosis was unchanged for 61 patients (94%) and the surgical plan did not change for 52 patients (80%). The main reason for surgical plan change was due to updated findings on new imaging, 10 patients, (77%). CONCLUSIONS: The current study suggests that telemedicine evaluations can provide an effective means of preoperative assessment for spine patients. LEVEL OF EVIDENCE: Level 3.

Quantitative CT for Preoperative Assessment of Lumbar Degenerative Spondylolisthesis: The Unique Impact of L4 Bone Mineral Density on Single-Level Disease.

Background: Quantitative computed tomography (qCT) efficiently measures 3-dimensional vertebral bone mineral density (BMD), but its utility in measuring BMD at various vertebral levels in patients with lumbar degenerative spondylolisthesis (LDS) is unclear. Purpose: We sought to determine whether qCT could differentiate BMD at different levels of LDS, particularly at L4-L5, the most common single level for LDS. In addition, we sought to describe patterns of BMD for single-level and multiple-level LDS. Methods: We conducted a study of patients undergoing surgery for LDS who were part of a larger longitudinal study comparing preoperative and intraoperative images. Preoperative patients were grouped as single-level or multiple-level LDS, and qCT BMD was obtained for L1-S1 vertebrae. Mean BMD was compared with literature reports; in multivariable analyses, BMD of each vertebra was assessed according to the level of LDS, controlling for covariates and for BMD of other vertebrae. Results: Of 250 patients (mean age: 67 years, 64% women), 22 had LDS at L3-L4 only, 170 at L4-L5 only, 13 at L5-S1 only, and 45 at multiple levels. Compared with other disorders reported in the literature, BMD in our sample similarly decreased from L1 to L3 then increased from L4 to S1, but mean BMD per vertebra in our sample was lower. Nearly half of our sample met criteria for osteopenia. In multivariable analysis controlling for BMD at other vertebrae, lower L4 BMD was associated with LDS at L4-L5, greater pelvic incidence minus lumbar lordosis, and not having diabetes. In contrast, in similar multivariable analysis, greater L4 BMD was associated with LDS at L3-L4. Bone mineral density of L3 and L5 was not associated with LDS levels. Conclusion: In our sample of preoperative patients with LDS, we observed lower BMD for LDS than for other lumbar disorders. L4 BMD varied according to the level of LDS after controlling for covariates and BMD of other vertebrae. Given that BMD can be obtained from routine imaging, our findings suggest that qCT data may be useful in the comprehensive assessment of and strategy for LDS surgery. More research is needed to elucidate the cause-effect relationships among spinopelvic alignment, LDS, and BMD.

The Spine Physical Examination Using Telemedicine: Strategies and Best Practices.

STUDY DESIGN: Technical note. OBJECTIVES: To provide spine surgeons new to telemedicine with a structured physical examination technique based on manual motor testing principles. METHODS: Expert experience describing a series of specific maneuvers for upper and lower extremity strength testing that can be performed using a telemedicine platform. In addition, we offer instruction on "setting up" for these visits and highlight special tests that can be used to diagnose specific cervical and lumbar spine conditions. RESULTS: From our experiences in conducting telemedicine visits, we provide a means of testing and scoring upper and lower extremity strength for interpretation of weakness in the context of traditional manual motor testing. Also, we acknowledge the limitations of a remote examination and discuss maneuvers that cannot be performed remotely. CONCLUSIONS: COVID-19 has drastically altered the delivery of care for patients with spine-related complaints. The need for social distancing has led to the widespread adoption of telemedicine. This technical note provides an urgently needed framework for the standardization of the remote physical exam. Validation of the exam as a diagnostic tool will be a crucial next step in studying the impact of telemedicine.

Computed Tomography and Magnetic Resonance Imaging Overlay in the Spine for Surgical Planning: A Technical Report.

BACKGROUND: Computed tomography (CT) and magnetic resonance imaging (MRI) studies are used separately for surgical planning of spine surgery. Advanced techniques exist for creating CT-MR fusion images, but at this time these techniques are not easily accessible for large-scale use. TECHNIQUE: We propose a simple graphical technique for CT-MR image overlay, for use in the surgical planning of spinal decompression and guidance of intraoperative resection. The proposed technique involves overlaying a single cross-section from anatomically comparable MRI and CT studies on any software with basic image editing functions. RESULTS: We demonstrate CT-MR fusion images of 8 patients of the senior author in which the technique was used. We found that it can also be referenced intraoperatively for navigation. CONCLUSIONS: Compared to other techniques, our proposed method can be easily implemented by clinicians to create simple CT-MRI fusion images that can be useful for preoperative planning and intraoperative navigation.