Late-week Multilevel Anterior Cervical Discectomy and Fusion Associated with Increased Length of Stay.

STUDY DESIGN: Retrospective analysis of clinical data from a single institution. OBJECTIVE: To assess the day of surgery during the week as a possible predictor of length of stay (LOS) following anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: Surgeries later in the week may result in longer LOS and higher costs for joint arthroplasty, yet this is unclear following spine surgery. Procedures performed later in the week may lead to weekend admissions when there are limited services that may contribute to an extended LOS. We attempt to identify associations between day of surgery and LOS, readmission, and complications following single- and multilevel ACDF. MATERIALS AND METHODS: Patients at a single institution undergoing ACDF by 7 primary surgeons in both orthopedic and neurosurgery spine departments between 2015 and 2019 were retrospectively reviewed. Patients were stratified by surgery day at either the beginning (Monday/Tuesday) or end (Thursday/Friday) of the week and by single- or multilevel ACDF. Surgery for trauma, infections, adjacent level disease, or revision were excluded. Patient demographics, Charlson Comorbidity Index (CCI), LOS, postoperative complications, and readmission rates were assessed. RESULTS: Six hundred fifty-two patients underwent ACDF. For single-level ACDF, 222 were reviewed, with 112 having surgery at the beginning and 110 at the end of the week. For multilevel ACDF, 431 were reviewed, with 192 having surgery at the beginning and 239 at the end of the week. No differences in pre- or postoperative variables were determined for single-level ACDF. Despite no differences in pre-operative variables, CCI, operative duration, or number of levels, late-week multilevel ACDF had longer average LOS (2.8±3.0 days) compared to early-week surgery (2.0±2.0 days) (P=0.018). CONCLUSIONS: Late-week multilevel ACDF was associated with an increased LOS, as it may prove beneficial to surgical planning. This conflicts with previous reports that day of week was not associated with LOS following ACDF. LEVEL OF EVIDENCE: III.

Feasibility of Machine Learning in the Prediction of Short-Term Outcomes Following Anterior Cervical Discectomy and Fusion.

BACKGROUND: Increased emphasis is being placed on efficiency and resource utilization when performing anterior cervical discectomy and fusion (ACDF), and accurate prediction of complications is increasingly important to optimize care. This study aimed to compare predictive models for postoperative complications following ACDF using machine learning (ML) models based on traditional comorbidity indices. METHODS: In this retrospective case series, the American College of Surgeons National Surgical Quality Improvement Program database was queried between 2011 and 2017 for all elective, primary ACDF cases. Levels of surgery, use of interbody implants, and graft selection were calculated by procedural codes. Six ML algorithms were constructed using available preoperative and intraoperative features. The overall dataset was randomly split into training (80%) and validation (20%) subsets wherein the training subset optimized the model, and the validation subset was evaluated for accuracy. ML models were compared with models constructed from American Society of Anesthesiologists classification and frailty index alone. RESULTS: There were 42,194 ACDF cases eligible for inclusion. Mean age was 47.7 ± 11.6 years, body mass index was 30.4 ± 6.7, and levels of operation were 1.6 ± 0.7. ML algorithms uniformly outperformed comorbidity indices in predicting complications. Logistic regression ML algorithm was the best performing for predicting any adverse event (area under the curve [AUC] 0.73), transfusion (AUC 0.90), surgical site infection (AUC 0.63), and pneumonia (AUC 0.80). Gradient boosting trees ML algorithm was the best performing for predicting extended length of stay (AUC 0.73). CONCLUSIONS: ML algorithms modeled the development of postoperative adverse events with superior accuracy to that of comorbidity indices and may guide preoperative clinical decision making before ACDF.

The Effect of State-Level Prescription Opioid Legislation on Patient Outcomes After Lumbar Tubular Microdecompression.

BACKGROUND: In the United States, a statewide legislation titled the Strengthen Opioid Misuse Prevention (STOP) Act was enacted in 2017 to limit prescription opioid use and reduce dependence. The impact of state legislation curbing opioid prescription on outcomes after spine surgery is unknown. STUDY DESIGN: Case series. METHODS: Data from consecutive patients undergoing lumbar tubular microdecompression for symptomatic lumbar spine stenosis from June 2016 to June 2019 were retrospectively analyzed. Cases between June 2016 and December 2017 represent the group before the STOP act (pre-STOP), while cases between January 2018 and June 2019 represent the group after legislation enactment (post-STOP). Preoperative and postoperative patient functional scores including the EuroQol-Five Dimensions Index, Oswestry Disability Index (ODI), and the visual analog scale (VAS) for back and leg pain were compared between both groups. The meaningful clinically important difference (MCID) was calculated for each score and was compared between both groups as well. RESULTS: A total of 147 patients met inclusion criteria, with 86 in the pre-STOP group and 61 in the post-STOP group. Analysis of postoperative scores demonstrated statistically lower VAS leg pain score averages in the post-STOP group (P < 0.05). Higher trends in achieving MCID among the post-STOP group were observed; however, the differences between both groups were not statistically significant (P > 0.05 for all). Additionally, there were no statistical differences in rates of unplanned pain-related clinic visits and emergency department (ED) visits, as well as no differences in the number of pain-related calls within 90 days after surgery between both groups. CONCLUSION: The enactment of state legislation to curb the prescribing of opioids for postoperative pain did not negatively affect the rate of achieving clinically meaningful outcomes among patients undergoing lumbar tubular microdecompression for spinal stenosis. Additionally, decreasing the amount of opioids prescribed for postoperative pain does not increase the number of unplanned clinic or ED visits due to pain within 90 days after surgery.

Predictors of Above Average 6-Year Citation Rates in Leading Spine-Specific Medical Journals.

STUDY DESIGN: Cross-sectional. OBJECTIVE: To identify predictors of manuscripts achieving 6-year citation rates higher than the mean in spine-specific literature. SUMMARY OF BACKGROUND DATA: An article's citation rate demonstrates its contribution to academia and its quality. Predictors of citation rates have not yet been studied in spine-specific medical literature. METHODS: Three leading spine-specific journals were identified by a weighted scoring system comparing various journal metrics. Research articles published in 2014 were evaluated from the following journals: Spine, European Spine Journal, and Journal of Neurosurgery: Spine. Article features analyzed included journal of origin, number of words in article title, author count, degree of first author, conflicts of interest, quantity of contributing academic institutions, country of origin, study topic, study design, level of evidence, sample size, reference count, and citation rate. Multivariate logistic regression was used to determine predictors of above average citation rate at 6 years following publication. RESULTS: The final analysis included 1091 articles. Spine had a significantly higher citation rate than European Spine Journal (P = 0.0008); however, no significant differences were observed between Spine and Journal of Neurosurgery: Spine. Regression analysis demonstrated that studies originating in North America (OR:1.44, 95% CI:1.01-2.01, P = 0.04), those with 6 ≥ authors (OR:1.72, 95% CI:1.29-2.30, P < 0.001), sample size >100 (P < 0.001), prospective case series (OR: 2.67, 95% CI: 1.24-5.76), and retrospective case series (OR: 1.99, 95% CI: 1.07-3.73) were independent predictors of achieving above average 6-year citation rates. CONCLUSION: Spine, European Spine Journal, and Journal of Neurosurgery: Spine had the highest 6-year citation rates of the top 10 orthopedic spine journals, with Spine being significantly higher than European Spine Journal. Studies originating in North America, those with six or more authors, sample sizes > 100, and those that are retrospective or prospective case series are independent predictors of greater citation rates at 6 years in orthopedic spine-specific medical literature.Level of Evidence: 4.

The effect of smoking on achieving meaningful clinical outcomes one year after lumbar tubular microdecompression: a matched-pair cohort analysis.

BACKGROUND CONTEXT: There has been a shift in the spine literature in reporting meaningful outcomes, including meaningful clinically important difference (MCID), after surgery. The evidence on the effect of tobacco smoking at the time of lumbar tubular microdecompression (LTMD) on meaningful outcomes is limited. PURPOSE: To compare differences in 1-year functional outcomes and rates of achieving MCID between current smokers and non-smokers who underwent LTMD for lumbar spinal stenosis (LSS). STUDY DESIGN: A nested case control study to compare the difference in patient reported outcomes (PROs) between smokers and non-smokers 1-year after undergoing LTMD. PATIENT SAMPLE: This study included patients that underwent single level LTMD by a single surgeon between January 2014 through August 2019. OUTCOME MEASURES: Preoperative and postoperative PROs were recorded using the questionnaires EQ-5D, Oswestry Disability Index (ODI), and the visual analog scale (VAS) for back pain and leg pain. The MCID was also used. METHODS: Current tobacco smokers at the time of surgery were matched 1:2 to non-smokers by age (+/- 1year). Preoperative and postoperative functional scores were compared between the two groups using independent t-tests. Additionally, thresholds for achieving MCID were calculated for each individual functional score, and were compared using Fisher's exact test. RESULTS: Of the 183 patients with 1-year follow-up who met inclusion criteria, 35 patients were identified as smokers and were matched to 70 non-smokers. No statistical differences were identified between age, BMI, or gender. Comparison of preoperative PROs showed no statistically significant differences between smokers and non-smokers (p>0.05 for all), while smokers had statistically lower EQ-5D (p<0.001) and higher ODI (p=0.05), VAS back (p=0.033), and VAS leg (p=0.03) score averages at a minimum of one year follow-up. Evaluation of meaningful outcomes demonstrated non-smokers had higher rates of achieving MCID on at least 1 threshold score as compared to smokers (98.5% vs. 91.1%; p=0.043). CONCLUSIONS: Current smokers at the time of surgery have inferior postoperative EQ-5D scores, increased pain and disability, and lower odds of achieving the MCID at 1-year after undergoing LTMD when compared to patients without any smoking history.

Accurate prediction of lumbar microdecompression level with an automated MRI grading system.

OBJECTIVE: Lumbar spine MRI interpretations have high variability reducing utility for surgical planning. This study evaluated a convolutional neural network (CNN) framework that generates automated MRI grading for its ability to predict the level that was surgically decompressed. MATERIALS AND METHODS: Patients who had single-level decompression were retrospectively evaluated. Sagittal T2 images were processed by a CNN (SpineNet), which provided grading for the following: central canal stenosis, disc narrowing, disc degeneration, spondylolisthesis, upper/lower endplate morphologic changes, and upper/lower marrow changes. The grades were used to calculate an aggregate score. The variables and the aggregate score were analyzed for their ability to predict the surgical level. For each surgical level subgroup, the surgical level aggregate scores were compared with the non-surgical levels. RESULTS: A total of 141 patients met the inclusion criteria (82 women, 59 men; mean age 64 years; age range 28-89 years). SpineNet did not identify central canal stenosis in 32 patients. Of the remaining 109, 96 (88%) patients had a decompression at the level of greatest stenosis. The higher stenotic grade was present only at the surgical level in 82/96 (85%) patients. The level with the highest aggregate score matched the surgical level in 103/141 (73%) patients and was unique to the surgical level in 91/103 (88%) patients. Overall, the highest aggregate score identified the surgical level in 91/141 (65%) patients. The aggregate MRI score mean was significantly higher for the L3-S1 surgical levels. CONCLUSION: A previously developed CNN framework accurately predicts the level of microdecompression for degenerative spinal stenosis in most patients.

Cost and Complications of Single-Level Lumbar Decompression in Those Over and Under 75: A Matched Comparison.

STUDY DESIGN: Retrospective database analysis. OBJECTIVE: This study aimed to compare costs and complication rates following single-level lumbar decompression in patients under age 75 versus patients aged 75 and older. SUMMARY OF BACKGROUND DATA: Lumbar decompression is a common surgical treatment for lumbar pathology; however, its effectiveness can be debated in elderly patients because complication rates and costs by age group are not well-defined. METHODS: The Medicare database was queried through the PearlDiver server for patients who underwent single-level lumbar decompression without fusion as an index procedure. The 90-day complication and reoperation rates were compared between age groups after matching for sex and comorbidity burden. Same day and 90-day costs are compared. RESULTS: The matched cohort included 89,388 total patients (n = 44,694 for each study arm). Compared to the under 75 age group, the 75 and older age group had greater rates of deep venous thrombosis (odds ratio [OR] 1.443, P = 0.042) and dural tear (OR 1.560, P = 0.043), and a lower rate of seroma complicating the procedure (OR 0.419, P = 0.009). There was no difference in overall 90-day reoperation rate in patients under age 75 versus patients aged 75 and older (9.66% vs. 9.28%, P = 0.051), although the 75 and older age group had a greater rate of laminectomy without discectomy (CPT-63047; OR 1.175, P < 0.001), while having a lower rate of laminotomy with discectomy (CPT-63042 and CPT-63030; OR 0.727 and 0.867, respectively, P = 0.013 and <0.001, respectively). The 75 and older age group had greater same day ($3329.24 vs. $3138.05, P < 0.001) and 90-day ($5014.82 vs. $4749.44, P < 0.001) mean reimbursement. CONCLUSION: Elderly patients experience greater rates of select perioperative complications, with mildly increased costs. There is no significant difference in overall 90-day reoperation rates. LEVEL OF EVIDENCE: 3.

Defining a Minimum Clinically Important Difference in Patient-Reported Outcome Measures in Lumbar Tubular Microdecompression Patients.

BACKGROUND: Patient-reported outcome measures (PROMs) are critical tools used in the assessment and reporting of surgical outcomes. However, significant differences in PROM scores have not been shown to consistently correlate with clinical improvement from the physician or patient perspective. Defining a minimum clinically important difference (MCID) for PROMs offers interpretation of surgical outcomes with an emphasis on patient-centered feedback. The goal of this study was to define a MCID for the following PROMs in lumbar tubular microdecompression (LTMD) patients: the EuroQol-Five Dimensions (EQ-5D) index, Oswestry Disability Index (ODI), leg pain visual analog scale (VAS), and low back pain VAS. METHODS: This study examined 235 index LTMD patients with PROMs collected at preoperative evaluation and 1-year follow-up. Using an anchor-based approach with patient satisfaction index, a receiver operating characteristic analysis was performed to define a MCID in the EQ-5D index, ODI, leg pain VAS, and low back pain VAS. RESULTS: The patients had a mean age of 65.18 ± 12.81 years, and 47.7% were male. The MCID values for the EQ-5D, ODI, leg pain VAS, and low back pain VAS are 0.219, 15.0-16.5, 0.5, and 2.5-3.5, respectively. CONCLUSIONS: This study helps define a MCID for the EQ-5D index in LTMD patients. Given its ease of administration and economic relevance, further characterization of the EQ-5D index may warrant its use as a potential alternative or adjunct to the routinely collected PROMs following spine surgery. LEVEL OF EVIDENCE: 3.

Lumbar microdecompression in elderly versus general adult patients: Comparable outcomes and costs despite group differences.

This study investigated differences between patients <65 and ≥65 years of age following lumbar microdecompression. Differences between age groups were investigated with univariate analyses. A linear mixed effects model was fit to the study outcomes. 144 patients were studied. There was no difference in two-year outcomes between the age groups. Outcome measures showed improvement compared to baseline at one- and two-years (p < 0.001). Age group had a significant effect on back pain (p = 0.016). Patients ≥65 years of age may experience greater relief in back pain following microdecompression. Nonetheless, significant improvement is observed in both age groups at two-years.

Should the EuroQol-Five Dimensions Replace the Oswestry Disability Index When Tracking Lumbar Tubular Microdecompression Outcomes?

OBJECTIVE: Patient-reported outcomes measures (PROMs) are critical in evaluating the effectiveness of surgical spine interventions. The Oswestry Disability Index (ODI) is commonly used but tedious to administer routinely. The EuroQol-5 Dimensions (EQ-5D) questionnaire is easier to administer but not traditionally used to measure spine surgical results. This study aimed to investigate the correlation of commonly administered PROMs in lumbar tubular microdecompression patients, and to consider whether ODI could be predicted from remaining PROMs. METHODS: This study examined 304 index lumbar tubular microdecompression patients with PROMs collected at routine intervals. Spearman correlation coefficients were calculated for each pairwise combination of the following PROMs: ODI, EQ-5D index, leg pain visual analog scale (VAS), low back pain VAS, health state item. Linear regression modeling was conducted to predict ODI from the remaining four PROMs. RESULTS: The patients had a mean age of 65.55 ± 12.97 years and 46.4% were male. Each combination of PROMs demonstrated a statistically significant pairwise correlation (P < 0.001). ODI showed strong correlation with EQ-5D index (r = -0.77), leg pain VAS (r = 0.73), and back pain VAS (r = 0.65), but weak correlation with health state item (r = -0.33). Forwards stepwise model selection yielded a multiple linear regression model including all four PROMs predictors, with an adjusted R2 of 0.690. There was strong correlation between predicted and observed ODI (r = 0.83, P < 0.001). CONCLUSIONS: ODI can be predicted from EQ-5D, leg and low back pain VAS, and health state items with moderate accuracy. The added utility of capturing ODI routinely may not out-weigh the challenges in doing so.

Epidural Abscess in the Lumbar Spine: A Single Institution's Experience With Nonsurgical and Surgical Management.

The purpose of this study was to compare patient factors and outcomes in conservatively and surgically treated patients with spinal epidural abscess (SEA). This was a single-center retrospective review of adult patients treated for SEA of the lumbar spine. Primary treatment outcome was readmission for recurrent abscess. Sixty-one patients met inclusion criteria: 59% male, mean age 56.9 years, and body mass index 30.8 kg/m2. Initially 47.5% of patients were treated with conservative measures and 52.5% were treated with surgery. In the conservative group, 31.0% failed treatment and underwent delayed surgery; 26.2% of the overall cohort was readmitted for SEA. Readmitted patients had a greater incidence of history of methicillin-resistant Staphylococcus aureus (p = .048), recurrent infections (p = .008), and recent sepsis and bacteremia (p = .005). Nearly one-third of patients failed initial conservative treatment and needed delayed surgery; however, no significant differences were found between the two treatment groups. Patients with a past history of infections may require more aggressive treatment and closer follow-up, because they are at higher risk for recurrence and readmission. (Journal of Surgical Orthopaedic Advances 28(3):224-231, 2019).

Far Lateral Tubular Decompression: A Case Series Studying One and Two Year Outcomes with Predictors of Failure.

Introduction The optimal surgical treatment of isolated lumbar foraminal stenosis has not been defined. Minimally invasive decompression of the foramen from a far lateral tubular decompression (FLTD) approach has been shown to not only have minimal morbidity but also highly variable success rates at short-term follow-up. It is important to quantify improvement and define the demographic and radiographic parameters that predict failure in this promising, minimally invasive surgical technique. This study investigates pain and disability score improvement following FLTD at 12 and 24 months and investigates associations with failure. Methods All patients who underwent lumbar FLTD by a single surgeon at a single institution from September 2015 to January 2018 were included in this prospective case series. Visual analog scale (VAS) for back pain and leg pain and Oswestry Disability Index (ODI) were collected preoperatively and at the 12- and 24- month follow-ups. Outcomes between visits were fitted to a linear mixed-effects model. The univariate analysis investigated demographic, radiographic, and operative associations with subsequent open revision. Results A total of 42 patients were included in this study. Back pain (VAS 5.84 to 3.32, p<0.001), leg pain (VAS 7.33 to 2.71, p<0.001), and ODI (48.97 to 28.50, p<0.001) demonstrated significant improvements at the 12-month follow-up. Back pain (VAS 3.71, p=0.004), leg pain (VAS 3.04, p<0.001), and ODI (30.63, p<0.001) improvements were maintained at 24-month follow-up. Four patients (9.5%) required subsequent open revision. Subsequent open revision was associated with prior spine surgery (RR=2.85 (2.07-3.63), p=0.045) and scoliosis ≥10° (RR=6.33 (4.87-7.80), p=0.013). Conclusion Back pain, leg pain, and ODI showed significant improvement postoperatively. Improvement is maintained at two years. Prior spine surgery and scoliosis ≥ 10° may be relative contraindications to FLTD.

Unilateral Laminotomy with Bilateral Decompression: A Case Series Studying One- and Two-Year Outcomes with Predictors of Minimal Clinical Improvement.

OBJECTIVE: To assess factors that may predict failure to improve at 12 and 24 months after unilateral laminotomy with bilateral decompression (ULBD) for the management of lumbar spinal stenosis. METHODS: A database of 255 patients who underwent microdecompression surgery by a single orthopedic spine surgeon between 2014 and 2018 was queried. Patients who underwent primary single-level ULBD of the lumbar spine were included. Visual analog scale (VAS) for back pain and leg pain and Oswestry Disability Index (ODI) results were collected preoperatively and at 12 and 24 months postoperatively. Demographic, radiographic, and operative factors were assessed for associations with failure to improve. Clinically important improvement was defined as reaching or surpassing the previously established minimum clinically important difference for ODI (12.8) and not requiring revision. RESULTS: A total of 68 patients were included. Compared with preoperative values for back pain, leg pain, and ODI (7.32, 7.53, and 51.22, respectively), there were significant improvements on follow-up at 12 months (2.89, 2.23, and 22.40, respectively; P < 0.001) and 24 months (2.80, 2.11, 20.32, respectively; P < 0.001). Based on the defined criteria, 50 patients showed clinically important improvement after ULBD. Of the 18 patients who failed to improve, 12 required revision. Independent predictors of failure to improve included female sex (adjusted odds ratio, 5.06; 95% confidence interval, 1.49-21.12; P = 0.014) and current smoker status (adjusted odds ratio, 5.39; 95% confidence interval, 1.39-23.97; P = 0.018). CONCLUSIONS: ULBD for the management of lumbar spinal stenosis leads to clinically important improvement that is maintained over a 24-month follow-up period. Female sex and tobacco smoking are associated with poorer outcomes.

Evaluation of Percutaneous Intradiscal Amniotic Suspension Allograft in a Rabbit Model of Intervertebral Disc Degeneration.

STUDY DESIGN: A laboratory study using a rabbit annular puncture model of intervertebral disc degeneration (IDD). OBJECTIVE: The aims of this study were to assess whether an amniotic suspension allograft (ASA) containing particulated human amnion and amniotic fluid derived cells regains intervertebral disc height and morphology and improves histologic scoring in a rabbit model of IDD. SUMMARY OF BACKGROUND DATA: In contrast to current surgical interventions for IDD, in which the primary goal is to relieve symptomatic pain, one novel strategy involves the direct injection of anabolic cytokines. Current therapies for IDD are limited by both the short half-life of therapeutic proteins and general decline in anabolic cell populations. METHODS: Intervertebral discs in New Zealand white rabbits were punctured using 18-gauge needle under fluoroscopic guidance. Four weeks post-puncture, two groups of rabbits were injected with either ASA or a vehicle/sham control, while a third group was untreated. Weekly radiographs were obtained for 12 weeks to assess disc height index (DHI). Magnetic resonance imaging (MRI) T2 relaxation time was evaluated at weeks 4 and 12 to assess morphological changes. Histologic sections were evaluated on a semi-quantitative grading scale. RESULTS: Before treatment at week 4, DHIs and normalized T2 relaxation times between the three groups were not significantly different. At week 12, ASA-treated rabbits exhibited significantly greater DHIs and MRI T2 relaxation times than vehicle and untreated control groups. The ASA group had higher mean histologic score than the vehicle group, which demonstrated extensive fiber disorganization and delamination with reduced proteoglycan staining on histology. CONCLUSION: Minimally invasive intervention with intradiscal injection of ASA was successful in reducing IDD in a reproducible rabbit model, with significant improvement in disc height and morphology when compared with vehicle and untreated control groups on radiographic and MRI analyses. LEVEL OF EVIDENCE: N/A.

A percutaneous, minimally invasive annulus fibrosus needle puncture model of intervertebral disc degeneration in rabbits.

PURPOSE: Various animal models have been proposed to mimic the pathophysiologic process of intervertebral disc degeneration, a leading cause of back pain. The purpose of this study is to describe a minimally invasive technique via percutaneous needle puncture of the annulus fibrosus in New Zealand white rabbits. METHODS: Under fluoroscopic guidance, an 18-gauge spinal needle was inserted 2 cm lateral to the midline spinous process. The needle was slowly advanced at approximately 45° angle until it was adjacent to the L5/L6 disc space. Lateral and anteroposterior views were used to verify correct needle position before advancing into the nucleus pulposus. The rabbits underwent weekly X-rays for 4 weeks to assess disc height index. MRI T2 relaxation was evaluated at week four to assess morphological changes. Discs were histologically graded on a 12-point scale to assess degeneration and compared to discs obtained from uninjured rabbits. RESULTS: There were no complications associated with the percutaneous needle puncture procedure. All animals survived the duration of the experiment. Four weeks after injury, the disc height had progressively narrowed to approximately 50% of baseline. MRI assessment at the 4-week time point demonstrated a mean T2 relaxation time at the L5/L6 level that was 20.9% of the T2 relaxation time at the uninjured L4/L5 disc level ( p < 0.001). Histological analysis demonstrated lamellar disorganization of the annulus and decreased cellularity and proteoglycan content within the injured nucleus compared to uninjured control discs. CONCLUSION: The present study demonstrated a reliable technique of inducing an annular tear via a percutaneous needle puncture. Compared to open surgical approaches, the percutaneous model produces similar progressive disc degeneration while minimizing harm to the animal subjects. CLINICAL RELEVANCE: The present study establishes a technique for the introduction of novel therapeutic agents to treat disc degeneration that may translate to future clinical trials.