Rajkishen Narayanan

Study design: Prospective trial. Objective: To evaluate the impact on muscle activation of different anatomical configurations of transcutaneous spinal cord stimulation electrodes amongst SCI and control patients. Summary of background data: Spinal cord stimulation has garnered increased attention as a promising treatment for spinal cord injury (SCI). However, existing studies on transcutaneous spinal cord stimulation consist of highly variable methodologies and lack standard protocols. Methods: Two adult SCI participants (PS01—T12 AIS D, and PS02—T2 AIS B) and two healthy adult controls (PS03, and PS04) were prospectively enrolled after IRB approval. Electromyography was used to record activity in the bilateral tibialis anterior (TA) and biceps femoris (BF). Four electrode configurations were trialed—cathode placement only at T11-T12 (montage T11-T12) versus combined configurations with cathodes at T11-T12 and at L1-L2, L3-L4, or S1-S2; anode placement was always at the bilateral iliac crests. Motor response was defined as EMG change >20 μV, as defined in the literature. Results: SCI participants exhibited overall decreased motor responses compared to controls, other than PS01 at the T11-T12 montage. The majority of motor responses from SCI participants did not meet the 20 µV threshold, and did not show the same consistent cranial to caudal pattern. PS01’s highest response was at T11-T12/L1-L2 (BF: 265.52 µV), whereas PS02 was highest at T11-T12 (TA: 39.73 µV). Overall, the motor response from the motor complete SCI (PS02—T2 AIS B) was substantially less than the motor response from the motor and sensory incomplete SCI. Conclusion: When performing transcutaneous spinal cord stimulation, the magnitude of motor response appears to vary with both the exact anatomical electrode configuration and the presence/severity of SCI. SCI participants demonstrated generally decreased motor responses, and a less predictable topographic pattern. Further work is needed to determine the ideal electrode configurations for different patients and spinal cord injury types.

Purpose: To examine whether clinical outcomes and patient-reported outcomes (PROMs) differ when patients are stratified by operative level in 3-level ACDF procedures. Methods: In this retrospective single-institution cohort study, patients undergoing 3-level ACDF (2014–2020) were reviewed for demographics, clinical outcomes, and PROMs. Patients with operative indications of infection/cancer/trauma/deformity were excluded. Patients with incomplete preoperative or 1-year postoperative PROMs were also excluded. PROMs, including SF-12, VAS Neck, VAS Arm, mJOA, and NDI, were assessed preoperatively and at 3, 6, and 12 months postoperatively. One-year MCID achievement was calculated using established thresholds. Patients were stratified and compared by construct level (C3-C6, C4-C7, and C5-T1). Results: Patients undergoing C3–C6 fusions were older than those in the C4–C7 group (62.7 versus 58.1 years, P = 0.007). The C5–T1 cohort had a higher 2-year reoperation rate compared to the C4–C7 cohort (18.2% versus 0.77%, P = 0.048). Baseline VAS Arm scores were worse in the C4–C7 group, with greater improvement at 1 year compared to the C3–C6 group (–3.45 versus − 2.27, P = 0.047). A transient difference in NDI at 3 months resolved by 6 months. MCID achievement rates across all PROMs did not differ significantly between groups. Conclusion: In patients undergoing 3-level ACDF, the operative level was associated with reoperation rates and baseline symptom profiles. However, the likelihood of achieving clinically meaningful improvements was similar across levels. Our findings support the need for construct-specific preoperative counseling while reinforcing the overall efficacy of 3-level ACDF across cervical levels.

Study Design: Retrospective cohort. Objectives: To compare demographic and microorganism culture data between primary and postoperative infections Background: Current literature suggests that both de novo and postoperative infection rates are increasing. At present, there is a paucity of research directly comparing de novo and postoperative spinal infections. Methods: Patients aged 18 years or older who underwent an irrigation and debridement (I&D) for de novo spine infections and infections following elective spine surgeries from 2017 to 2023 were compared. All patients were retrospectively reviewed for demographic information, comorbidities, and social history. Tissue microbiology of both cohorts was compared by broad classes (eg, gram-positive vs gram-negative, aerobic vs anaerobic, monomicrobial vs polymicrobial) and individual microbes (eg, Staphylococcus aureus , E. Coli , Pseudomonas, etc). Statistical analysis was performed, and P -value P = 0.002) with lower BMIs ( P < 0.001) and were more likely to be current smokers ( P = 0.005). These patients also had higher rates of hepatitis C ( P < 0.001), CKD ( P = 0.009), and prior IV drug use ( P < 0.001). De novo infections had higher rates of gram-positive ( P = 0.004), monomicrobial ( P = 0.013), and aerobic ( P = 0.026) infections than postoperative infections. Staphylococcus aureus infection rates were statistically similar between groups ( P = 0.138), while Streptococcus was more common in the postoperative infection cohort ( P = 0.002). Pseudomonas, proteus, and Corynebacterium were identified significantly more often in the postoperative infection cohort. Conclusions: Patients developing de novo and postoperative spine infections exhibit notable demographic and microorganism differences. Adequate treatment of patients with spinal infections, therefore, requires an awareness of both medical and social factors most prevalent within these two populations.

Intervertebral disk pathology, including disk herniation and degeneration, is a major contributor to chronic low back pain, and when conservative treatment fails, surgical management often involves discectomy-based procedures that leave residual annulus fibrosus (AF) defects associated with reherniation and progressive degeneration. These limitations have motivated interest in regenerative strategies using biomaterial scaffolds; however, reproducing the hierarchical, angle-ply architecture of the AF remains challenging. Here, we present a single-step extrusion-based 3D-printing approach to fabricate polycaprolactone (PCL) scaffolds with aligned microscale surface grooves that promote AF-like organization. Patterned nozzles with circumferential peaks generated uniaxial concave microgrooves (10–17 µm wide) directly during printing, enabling formation of multilamellar angle-ply constructs. Human bone marrow-derived mesenchymal stem cells cultured on patterned scaffolds aligned longitudinally within concave grooves, forming end-to-end arrays that guided extracellular matrix deposition. Gene expression analysis showed that topographical cues governed cellular organization without significantly altering gene expression profiles, while TGF-β3 supplementation upregulated outer AF-associated markers, including COL1, COL12, SFRP2, MKX, MCAM, and SCX. TAGLN expression increased specifically on patterned scaffolds in the absence of TGF-β3, indicating an association between microgroove-guided cellular organization and TAGLN expression, warranting further investigation into potential tension-related mechanisms. This novel single-step extrusion-printing approach leverages custom nozzle geometry to impart concave microgrooves, facilitating scalable fabrication of multilamellar angle-ply scaffolds that induce aligned cellular organization and support potential applications in annulus fibrosus repair, as well as mechanobiological studies of anisotropic musculoskeletal tissues.

Study Design: Retrospective Cohort Study. Objective: This study aimed to identify radiographic and patient-dependent factors that predict failure of epidural steroid injection (ESI) management, leading to subsequent surgical management in patients with lumbar stenosis. Summary of Background Data: Lumbar stenosis is a common cause of radiculopathy and neurogenic claudication, and ESIs are a mainstay of conservative care. However, the benefits of ESIs are debated, and limited evidence exists on how stenosis characteristics correlate with the need for eventual surgery post-ESI. Methods: Adult patients (N=581) who received ESIs for lumbar radiculopathy or spinal stenosis between 2018 and 2021 were retrospectively identified. Subsequent lumbar spine surgery within two years of the first ESI was the primary outcome. Central and foraminal stenosis were graded using preoperative MRIs according to the Guen and Lee classification systems, respectively. Pre- and post-injection pain scores were collected. Multivariate logistic regression was used to determine significant independent predictors of subsequent surgery, accounting for age, body mass index (BMI), diabetes, Charlson Comorbidity Index (CCI), total number of ESIs, central stenosis, and foraminal stenosis. Results: Significant predictors of needing surgery within two years of the first ESI were age (OR 0.96; P P =0.046), diabetes (OR 2.55, 95% CI [1.31, 4.96], P =0.010), total number of ESIs received (OR 1.83, 95% CI [1.46, 2.29], P P <0.001). Central stenosis severity was not a significant predictor of surgery following ESI. Conclusions: In patients treated with initial ESI, foraminal stenosis severity predicted the need for subsequent lumbar spine surgery. Additionally, age, BMI, diabetes, and cumulative number of ESIs were identified as independent predictors of surgery. These findings may assist physicians in counseling patients about the progression of their lumbar stenosis and in predicting the need for future surgery. Level of Evidence: III

Study Design: Retrospective cohort study. Objectives: To describe patterns of postoperative analgesia use (opioids, antidepressants, gabapentinoids, muscle relaxants, and benzodiazepines) among postoperative marijuana users after anterior cervical discectomy and fusion (ACDF) and lumbar fusion. Summary of Background Data: The use of marijuana for pain management is a controversial topic that lacks extensive research. As social and legal acceptance of marijuana increases, questions have arisen about its therapeutic potential alongside prescription analgesic pharmaceutical agents, necessitating further studies on this topic. Methods: Adult patients who underwent either ACDF or lumbar fusion surgery and used marijuana postoperatively were identified. A 1:1 propensity match incorporating patient demographics and levels fused was conducted to compare postoperative marijuana users to nonmarijuana users. One year preoperative and 1 year postoperative opioid use was obtained from the Pennsylvania Prescription Drug Monitoring Program (PDMP). Preoperative and postoperative utilization of antidepressants, gabapentinoids, muscle relaxants, and benzodiazepines was obtained from patient chart review and PDMP. Results: Of the 126 included patients, 63 (50%) used marijuana postoperatively. A greater proportion of marijuana users undergoing lumbar fusion used opioids preoperatively compared with nonmarijuana users ( P =0.048). No significant differences in preoperative opioid use were demonstrated among ACDF patients. In both ACDF and lumbar fusion cohorts, no differences in postoperative opioid consumption were observed between marijuana and nonmarijuana users. Marijuana usage was associated with higher utilization of serotonin-norepinephrine reuptake inhibitors (SNRIs), specifically duloxetine, in the ACDF cohort ( P =0.024). No significant differences in rates of utilization of tricyclic antidepressants, gabapentinoids, muscle relaxants, and benzodiazepines were observed in patients who consumed marijuana compared with nonmarijuana users. Conclusions: Postoperative marijuana use was significantly associated with preoperative opioid use in lumbar fusion patients and duloxetine use in ACDF patients. Postoperative marijuana use was not significantly associated with gabapentinoid, muscle relaxant, or benzodiazepine use.

Study Design: Retrospective cohort. Objective: To compare institutional and National Surgical Quality Improvement Program (NSQIP) patients who underwent either anterior cervical discectomy and fusion (ACDF) or posterior lumbar decompression and fusion (PLDF) to determine the congruency of baseline characteristics and postoperative outcomes. Background: Large database studies have grown in prominence owing to their inexpensive nature, and ability to draw on large sample sizes. However, concerns regarding the accuracy and limitations of database studies have generated significant debate. Materials and Methods: A total of 954 patients who underwent ACDF/PLDF at our institution, and 9875 ACDF/PLDF patients from NSQIP were included. The NSQIP cohort was propensity matched to the institutional cohort for single-level ACDF and single-level PLDF procedures. Statistical analysis included either t-tests or Mann-Whitney U tests for continuous variables and χ ² tests or Fisher exact tests for categorical variables. Results: The majority of postoperative complication rates did not differ significantly between the matched cohorts. Institution ACDF patients had shorter operative times and length of stay (LOS) compared with the NSQIP cohort. The institutional PLDF cohort had a higher 30-day readmission rate (3.13% vs 0.22%, P = 0.002) compared with the NSQIP PLDF cohort, while no differences were noted in 30-day readmission for ACDF. Institutional 90-day ACDF readmission rates were 2.36%, and institutional PLDF 90-day readmission rates were 7.14%, while NSQIP does not track 90-day readmission rates. Conclusions: The current study offers a rigorous comparative analysis of ACDF and PLDF outcomes from NSQIP and a single institution. Although large databases are valuable in understanding trends and rare events, clinicians should be advised of the limitations of database research, such as missing data, selection bias, and coding variations, and their relevance to the unique population encountered within institutions. Level of Evidence: Level III.

Study Design: Retrospective cohort study. Objective: The present study aims to compare outcomes for patients undergoing spinal fusion through PLDF and TLIF and determine whether specific radiographic characteristics, based upon both the CARDS and Meyerding classifications, might influence optimal fusion technique. Summary of Background Data: Despite the significant prevalence and high disease burden of degenerative spondylolisthesis (DS), consensus regarding surgical management is still lacking. Methods: Adult patients (≥18 years old) who underwent primary single-level lumbar fusion for degenerative spondylolisthesis were retrospectively identified. Preoperative flexion-and-extension lateral radiographs were reviewed to classify DS using the Meyerding grading system, as well as the validated Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) classification system. PROM scores were collected preoperatively and 1 year postoperatively and included the Oswestry Disability Index (ODI), Visual Analog Scale back and leg (VAS back and VAS leg, respectively), and the mental and physical component of the short-form 12 survey (MCS and PCS). Results: A total of 594 patients were identified. Patients with CARDS type A spondylolisthesis experienced greater improvement in ODI (−11.02 vs. −3.06, P =0.005) when they underwent TLIF; however, patients with CARDS class B experienced greater ODI improvement after a PLDF (−14.33 vs. −5.45, P P =0.006) and MCS (5.68 vs. 2.87, P =0.011) when they underwent PLDF compared with TLIF. There were no other differences in PROM improvement between approaches for other grades and classes. After controlling for patient characteristics, these differences persisted on linear regression analysis. Conclusion: Although there are several factors to consider, these results show that PLDF may be the optimal approach for degenerative spondylolisthesis patients with milder degrees of vertebral slippage. Patients with advanced disc collapse, endplate apposition, and kyphosis may benefit more from TLIF.