Clinical and radiologic outcomes of posterior column extension, pedicle subtraction, and vertebral column resection osteotomies in adult chin on chest deformity: A systematic review.

Background: Chin-on-chest deformity is a rare and severely disabling condition characterized by kyphotic deformity in the cervicothoracic spine. To treat this deformity, various osteotomy techniques were described. Methods: A comprehensive literature search of biomedical databases including MEDLINE (via PubMed), Scopus (via Elsevier), Embase (via Elsevier), and Cochrane Library in English from 1/1/1990 to 3/31/2022 was conducted using a combination of text and Medical Subject Headings (MeSH). Results: The final analysis included 16 studies. All the studies were assigned a level of evidence of four. Except for two articles, all of the articles were non-comparative studies. A total of 288 patients were included in this review. Of the 288 patients, 107 underwent posterior column extension osteotomy (PCEO), 108 underwent pedicle subtraction osteotomy (PSO), and 33 underwent vertebral column resection osteotomy (VCRO). The most common osteotomy level in fifteen of the studies was C7/T1. The studies included in this review described several techniques for cervical sagittal balance correction. The range of preoperative and postoperative visual analogue scale (VAS) scores was 5.5-8.6 to 1.7-4.91, respectively. The range of preoperative and postoperative neck disability index (NDI) was 34.2-65.4 to 22.1-51.3, respectively. The most common complications were upper extremity paresthesia and hand numbness through the C8 dermatome distribution. Conclusions: Corrective osteotomies provide satisfactory results in patients with chin-on-chest deformity; however, the quality of the included studies limits the evidence.

Sequential Depth Stimulation Within the Psoas Offers No Benefit for Localization of the Lumbar Plexus During Lateral Lumbar Fusion Surgery.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: In this study we aim to assess the difference in triggered EMG readings throughout different depths in the psoas muscle during the lateral approach to the lumbar spine and their effect on surgeon decision making. METHODS: Three surgeons, practicing at different institutions, assessed triggered EMG readings during the trans psoas approach at the level of the disc and 5,10 and 15 millimeters into the psoas muscle with sequential dilators. Measurement of distance into the psoas muscle was done with a specially designed instrument. Results of anterior and posterior directed stimulation as well as the delta value between these were recorded and underwent statistical analysis. Patients who had partial readings were excluded from the study. RESULTS: A total of 40 levels in 35 patients were included in the study. There was no significant difference found between means of anterior or posterior threshold readings along the different distance groups. A significant difference was found (P = .024) in the mean difference between the distance groups with a decrease in the difference between anterior and posterior threshold values found as the distance from the disc space increased. None of the surgeons reported a decision to abort the fusion of a spinal level. CONCLUSIONS: In the trans-psoas approach to the lumbar spine, the assessment of the location of the femoral nerve using directional neuromonitoring when advancing in the psoas muscle shows no clear benefit as opposed to stimulating solely when adjacent to the disc space.

C5 nerve root palsy (without prior cervical decompression) case series: 9 patients with critical delay to presentation.

BACKGROUND: Distinguishing between cervical nerve root and intrinsic shoulder pathology can be a difficult task given the overlapping and often coexisting symptoms. OBJECTIVE: The objective of this study was to highlight the often-complicated presentation of these symptoms and the subsequent potential for delay in care regarding this subset of patients. METHODS: A total of 9 patients, managed by one of two different surgeons, were identified with a history of C5 nerve root palsy. A chart review was conducted, and the following information was recorded: presenting complaint, time from symptom onset to diagnosis, time from symptom onset to presentation to a spine surgeon, first specialist seen for symptoms, non-spinal advanced imaging and treatment conducted before diagnosis, preoperative and postoperative exam, time to recovery, and type of surgery. RESULTS: We observed an average time from onset of symptoms to presentation to a spine surgeon to be 31.6 weeks. These patients' time to full recovery after cervical decompression was 15 weeks. CONCLUSION: : We observed a critical delay to presentation in this series of patients with C5 nerve palsy. C5 nerve palsy should remain an elemental part of the differential diagnosis in the setting of any shoulder or neck pain presenting with weakness.

The Effects of Preoperative Epidural Steroid Injection on Pseudarthrosis Following Lumbar Fusion: A Retrospective Cohort Study.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The goal of this study is to evaluate the effects of preoperative lumbar epidural steroid injection on the rate of pseudarthrosis following lumbar spine fusion surgery. SUMMARY OF BACKGROUND DATA: Epidural corticosteroids help to reduce nerve root edema and suppress proinflammatory cytokines in patients with radiculopathy. Corticosteroids may inhibit bone formation and reduce bone matrix synthesis rates. Thus, there is concern that corticosteroids may reduce lumbar fusion capability, potentially resulting in increased rates of symptomatic pseudarthrosis. MATERIALS AND METHODS: We identified all patients who underwent 1-level or 2-level lumbar fusion surgery between 2018 and 2022. Patients were categorized into one of 3 groups: no preoperative epidural steroid injection (ESI) history (group 0), preoperative ESI within 90 days of surgery (group 1), or most recent ESI >90 days before surgery (group 2). The primary outcome of this study was pseudarthrosis. Binominal regression analyses were performed to determine the relationships between potential risk factors (sex, age, body mass index, smoking history, diabetes status, history of systemic steroid use, preoperative ESI, perioperative intravenous steroid administration, type of surgery, and postoperative ESI within 6 mo) and the development of postoperative pseudarthrosis. RESULTS: A total of 446 patients were included in this study. Of those, 106 patients (23.7%) did not have a preoperative ESI (group 0), 132 patients (29.5%) had an ESI within 90 days of surgery (group 1), and 208 patients (46.6%) had their most recent ESI >90 days before surgery (group 2). The overall incidence of pseudarthrosis following lumbar fusion was 8.7% (39 of 446). Although the incidence of pseudarthrosis following ESI at any time point was higher than in our control cohort (group 0), this difference was not statistically significant. CONCLUSIONS: This study found no increased risk of postoperative pseudarthrosis in patients who underwent 1-level or 2-level lumbar fusions after preoperative ESI. LEVEL OF EVIDENCE: Level III.

Hydrogel-Based Strategies for Intervertebral Disc Regeneration: Advances, Challenges and Clinical Prospects.

Millions of people worldwide suffer from low back pain and disability associated with intervertebral disc (IVD) degeneration. IVD degeneration is highly correlated with aging, as the nucleus pulposus (NP) dehydrates and the annulus fibrosus (AF) fissures form, which often results in intervertebral disc herniation or disc space collapse and related clinical symptoms. Currently available options for treating intervertebral disc degeneration are symptoms control with therapy modalities, and/or medication, and/or surgical resection of the IVD with or without spinal fusion. As such, there is an urgent clinical demand for more effective disease-modifying treatments for this ubiquitous disorder, rather than the current paradigms focused only on symptom control. Hydrogels are unique biomaterials that have a variety of distinctive qualities, including (but not limited to) biocompatibility, highly adjustable mechanical characteristics, and most importantly, the capacity to absorb and retain water in a manner like that of native human nucleus pulposus tissue. In recent years, various hydrogels have been investigated in vitro and in vivo for the repair of intervertebral discs, some of which are ready for clinical testing. In this review, we summarize the latest findings and developments in the application of hydrogel technology for the repair and regeneration of intervertebral discs.

Complications of the Prone Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spine Disease: A Multicenter Study.

BACKGROUND AND OBJECTIVES: The prone transpsoas (PTP) approach for lateral lumbar interbody fusion (LLIF) is a novel technique for degenerative lumbar spine disease. However, there is a paucity of information in the literature on the complications of this procedure, with all published data consisting of small samples. We aimed to report the intraoperative and postoperative complications of PTP in the largest study to date. METHODS: A retrospective electronic medical record review was conducted at 11 centers to identify consecutive patients who underwent LLIF through the PTP approach between January 1, 2021, and December 31, 2021. The following data were collected: intraoperative characteristics (operative time, estimated blood loss [EBL], intraoperative complications [anterior longitudinal ligament (ALL) rupture, cage subsidence, vascular and visceral injuries]), postoperative complications, and hospital stay. RESULTS: A total of 365 patients were included in the study. Among these patients, 2.2% had ALL rupture, 0.3% had cage subsidence, 0.3% had a vascular injury, 0.3% had a ureteric injury, and no other visceral injuries were reported. Mean operative time was 226.2 ± 147.9 minutes. Mean EBL was 138.4 ± 215.6 mL. Mean hospital stay was 2.7 ± 2.2 days. Postoperative complications included new sensory symptoms-8.2%, new lower extremity weakness-5.8%, wound infection-1.4%, cage subsidence-0.8%, psoas hematoma-0.5%, small bowel obstruction and ischemia-0.3%, and 90-day readmission-1.9%. CONCLUSION: In this multicenter case series, the PTP approach was well tolerated and associated with a satisfactory safety profile.

Current Trends in Recombinant Human Bone Morphogenetic Protein 2 (rhBMP2) Usage for Spinal Fusion Surgery.

(1) Background: Since first approved by the FDA, on-label and off-label usage of recombinant human bone morphogenetic protein 2 (rhBMP2) for spinal fusion surgeries has become widespread. While many studies have investigated the safety and efficacy of its use, as well as its economic impact, few have looked at the current trends in its on- and off-label use. The goal of this study is to evaluate the current trends of on- and off-label rhBMP2 use for spinal fusion surgery. (2) Methods: A deidentified survey was created and electronically distributed to members of two international spine societies. Surgeons were asked to report their demographic information, surgical experience, and current usage of rhBMP2. They were then presented with five spinal fusion procedures and asked to report if they use rhBMP2 for these indications in their current practice. Responses were stratified between rhBMP2 users vs. non-users and on-label vs. off-label use. Data were analyzed using chi-square with Fisher's exact test for categorical data. (3) Results: A total of 146 respondents completed the survey with a response rate of 20.5%. There was no difference in overall rhBMP2 usage based on specialty, experience, or number of cases per year. Fellowship-trained surgeons and those who practice in the United States were more likely to use rhBMP2. Surgeons who were trained in the Southeast and Midwest regions reported the highest usage rates. rhBMP2 use was more common among fellowship-trained and US surgeons for ALIFs; non-US surgeons for multilevel anterior cervical discectomy and fusions; and fellowship-trained and orthopedic spine surgeons for lateral lumbar interbody fusions. Non-US surgeons were more likely to use rhBMP2 for off-label indications compared to surgeons from the US. (4) Conclusions: While various demographics of surgeons report different rates of rhBMP2 use, off-label use remains relatively commonplace amongst practicing spine surgeons.

The Prone Lateral Approach for Lumbar Fusion-A Review of the Literature and Case Series.

Lateral lumbar interbody fusion is an evolving procedure in spine surgery allowing for the placement of large interbody devices to achieve indirect decompression of segmental stenosis, deformity correction and high fusion rates through a minimally invasive approach. Traditionally, this technique has been performed in the lateral decubitus position. Many surgeons have adopted simultaneous posterior instrumentation in the lateral position to avoid patient repositioning; however, this technique presents several challenges and limitations. Recently, lateral interbody fusion in the prone position has been gaining in popularity due to the surgeon's ability to perform simultaneous posterior instrumentation as well as decompression procedures and corrective osteotomies. Furthermore, the prone position allows improved correction of sagittal plane imbalance due to increased lumbar lordosis when prone on most operative tables used for spinal surgery. In this paper, we describe the evolution of the prone lateral approach for interbody fusion and present our experience with this technique. Case examples are included for illustration.

Novel Injectable Fluorescent Polymeric Nanocarriers for Intervertebral Disc Application.

Damage to intervertebral discs (IVD) can lead to chronic pain and disability, and no current treatments can fully restore their function. Some non-surgical treatments have shown promise; however, these approaches are generally limited by burst release and poor localization of diverse molecules. In this proof-of-concept study, we developed a nanoparticle (NP) delivery system to efficiently deliver high- and low-solubility drug molecules. Nanoparticles of cellulose acetate and polycaprolactone-polyethylene glycol conjugated with 1-oxo-1H-pyrido [2,1-b][1,3]benzoxazole-3-carboxylic acid (PBC), a novel fluorescent dye, were prepared by the oil-in-water emulsion. Two drugs, a water insoluble indomethacin (IND) and a water soluble 4-aminopyridine (4-AP), were used to study their release patterns. Electron microscopy confirmed the spherical nature and rough surface of nanoparticles. The particle size analysis revealed a hydrodynamic radius ranging ~150-162 nm based on dynamic light scattering. Zeta potential increased with PBC conjugation implying their enhanced stability. IND encapsulation efficiency was almost 3-fold higher than 4-AP, with release lasting up to 4 days, signifying enhanced solubility, while the release of 4-AP continued for up to 7 days. Nanoparticles and their drug formulations did not show any apparent cytotoxicity and were taken up by human IVD nucleus pulposus cells. When injected into coccygeal mouse IVDs in vivo, the nanoparticles remained within the nucleus pulposus cells and the injection site of the nucleus pulposus and annulus fibrosus of the IVD. These fluorescent nano-formulations may serve as a platform technology to deliver therapeutic agents to IVDs and other tissues that require localized drug injections.

Early Clinical Outcomes of the Prone Transpsoas Lumbar Interbody Fusion Technique.

BACKGROUND: The prone transpsoas (PTP) approach for lateral lumbar interbody fusion (LLIF) is a relatively novel technique. Currently, little is known about its associated complications and early patient-reported outcomes. The aim of this study was to investigate the effect of LLIF performed via the PTP approach on sagittal radiographic parameters, patient-reported outcome measures (PROMs), and rates of complications. METHODS: A retrospective review was performed of 82 consecutive patients who underwent LLIF via a PTP technique. Lumbar lordosis (LL), segmental lordosis (SL), anterior disc height (ADH), and posterior disc height (PDH) were measured on preoperative, initial postoperative, and 3-month postoperative radiographs. PROMs including the Oswestry Disability Index (ODI); the visual analog scale (VAS); and pain portions of the EQ5D, VAS back, and VAS leg ratings were collected at the preoperative and subsequent postoperative visits. Length of hospital stay and postoperative complications related to the procedure were recorded. RESULTS: Significant improvements were seen at the initial (4.5° ± 8.6°, P < 0.001) and 3-month (4.4° ± 7.2°, P < 0.001) postoperative periods for LL, as well as SL (6.8° ± 4.8°, P < 0.001; 6.7° ± 4.4°, P < 0.001), ADH (8.0 mm ± 3.6, P < 0.001; 7.4 mm ± 3.6, P < 0.001), and PDH (3.3 mm ± 2.4, P < 0.001; 3.1 mm ± 2.5, P < 0.001). Significant improvements were seen at 3 months postoperatively for ODI (P < 0.001), EQ5D pain (P = 0.016), VAS leg (P < 0.001), and VAS back (P < 0.001). The average length of stay was 2.7 ± 4.5 days. The most common complications were ipsilateral thigh pain/numbness (45.1%), ipsilateral hip flexor weakness (39.0%), and contralateral thigh pain/numbness (14.6%). CONCLUSIONS: While early PROMs and correction of sagittal radiographic parameters show promising results for the PTP approach for LLIF, it is not without risks. CLINICAL RELEVANCE: PTP interbody fusion is an emerging technique that allows for simultaneous access to the anterior and posterior columns of the lumbar spine. This early case series demonstrates significant improvement in functional outcomes and lumbar lordosis with a safety profile comparable to other well-established techniques.

Radiographic alignment outcomes after the single-position prone transpsoas approach: a multi-institutional retrospective review of 363 cases.

OBJECTIVE: The aim of this paper was to evaluate the changes in radiographic spinopelvic parameters in a large cohort of patients undergoing the prone transpsoas approach to the lumbar spine. METHODS: A multicenter retrospective observational cohort study was performed for all patients who underwent lateral lumber interbody fusion via the single-position prone transpsoas (PTP) approach. Spinopelvic parameters from preoperative and first upright postoperative radiographs were collected, including lumbar lordosis (LL), pelvic incidence (PI), and pelvic tilt (PT). Functional indices (visual analog scale score), and patient-reported outcomes (Oswestry Disability Index) were also recorded from pre- and postoperative appointments. RESULTS: Of the 363 patients who successfully underwent the procedure, LL after fusion was 50.0° compared with 45.6° preoperatively (p < 0.001). The pelvic incidence-lumbar lordosis mismatch (PI-LL) was 10.5° preoperatively versus 2.9° postoperatively (p < 0.001). PT did not significantly change (0.2° ± 10.7°, p > 0.05). CONCLUSIONS: The PTP approach allows significant gain in lordotic augmentation, which was associated with good functional results at follow-up.

Does a relationship exist between preoperative expectations and overall satisfaction in spine surgery patients?-a prospective cohort study.

Background: The role of preoperative patient expectation in spine surgery is not completely understood, but could be essential in predicting patient outcomes. The purpose of this study was to create a standard means to assess patient preoperative expectations and its effect on postoperative satisfaction in the midterm follow-up period. Methods: This is a prospective cohort study design. Forty-five patients undergoing elective cervical or lumbar spine surgery were asked to participate in the study. Using a 10 cm visual analog scale (VAS) score, patients were asked to rate their preoperative pain along with what they expect it to be after surgery. Pre- and postoperative Oswestry Disability Index (ODI) and Neck Disability Index (NDI) were recorded. Overall satisfaction with surgery was recorded along with if they would have surgery again. The patients' preoperative expectations were compared to their postoperative ODI/NDI scores at terminal follow-up around 1 year. Postoperative satisfaction was also correlated as to whether they would have surgery again. Results: Patients who would have surgery again had an average expected decrease in their disability by 37 (±23) compared to 26 (±19) in patients who would not (P=0.201). For patients who would have surgery again, their postoperative pain more closely matched their preoperative expectations. Conclusions: In conclusion, the authors found that patients who were satisfied with their spine surgery improved functionally to a much greater degree from baseline, tended to have higher expectations with regards to level of disability improvement, and had lower expectations with regards to improvement in neck/back pain.

Pilocytic Astrocytoma Arising from the Conus Medullaris in an Adult: A Case Report.

Low-grade, sporadic, pilocytic astrocytomas (PAs) are rare spinal cord tumors diagnosed in adult patients. Their localization to the conus medullaris is exceedingly rare, having only been described in a limited number of case reports. Here, we describe a case of a 22-year-old female presenting with back pain, lower extremity weakness, hypoesthesia, and urinary incontinence. Imaging studies demonstrated a cystic lesion of the conus medullaris that was treated with subtotal resection and cyst-subarachnoid shunt placement. Final pathology report confirmed PA from the histology of surgical specimens. We discuss the current literature of conus medullaris lesions and their differential diagnosis.

Modifiable Patient Factors Demonstrate No Increased Risk for 30-Day Complication Rate for Elective 1-2 Level Posterior Lumbar Fusion Surgery: A Comparison Between a National Database and Local Registry.

BACKGROUND: While national databases provide large datasets that can be used to understand trends over time, their correlation with prospectively collected data from local registries has not been established. The purpose of the study was to compare differences in patient demographics and adverse events for patients undergoing elective posterior spinal fusion (PSF) between a national database and institutional registry. METHODS: A retrospective chart review was performed. A total of 14,618 patients (13,678 patients from the National Surgical Quality Improvement Program [NSQIP] database and 940 patients from the institutional registry) who underwent elective 1- to 2-level PSF were included in the study. Preoperative patient demographics and comorbidities of each cohort were compared. In addition, postoperative 30-day complications and readmission were collected. A multivariate analysis was performed to examine for differences in risk factors for 30-day adverse events between the 2 cohorts. RESULTS: A total of 13,678 patients from the NSQIP database and 940 patients from the institutional cohort were included for analysis. Mean age was similar between patient cohorts (60.8 ± 13.1NSQIP vs 58.8 ± 12.9registry), with NSQIP having significantly more patients over the age of 65 (41.4% vs 33.2%, P < 0.001). Overall complication rate was similar between NSQIP (6.8%) and the institutional registry (8.4%). Both found age and female sex to be significant predictors of 30-day adverse events, while obesity, hypertension, and smoking were only found to be predictive in the NSQIP database. CONCLUSIONS: Age and female sex were found to be independent risk factors for 30-day adverse events between both cohorts, while only NSQIP found modifiable comorbidities to be significant predictors. Although large databases allow for trends in quality over time, subtleties in practice variation and data collection methods at the individual institution level need to be considered when generalizing findings, especially as it pertains to modifiable factors. CLINICAL RELEVANCE: Quality metrics and risk factors for patient outcomes are often derived from national databases. This study highlights the differences between study results when outcomes are derived from an institutional registry compared to a national database.

Determination of a neurologic safe zone for bicortical S1 pedicle screw placement.

BACKGROUND CONTEXT: Lumbosacral fixation is commonly used for the management of lumbosacral instability. As the sacrum mainly consists of cancellous bone, bicortical fixation, in which the pedicle screw penetrates the anterior sacral cortex, can help increase the strength of fixation. However, this method carries a risk to the L5 nerves which lie anterior to the sacrum at this level. PURPOSE: The goal of this study is to determine a safe zone for the placement of S1 pedicle screws to decrease the likelihood of L5 nerve injury. STUDY DESIGN: Retrospective imaging review. PATIENT SAMPLE: This study evaluated imaging data of patients who underwent lumbar spine magnetic resonance imaging (MRI) at our institute between September 1, 2020 and September 1, 2021. OUTCOME MEASURES: T1-weighted axial MRIs were measured at the level of S1 pedicle screw placement. The space medial and lateral to the L5 nerve root on the anterior sacrum were measured and defined as safe zones. Additionally, the nerve width and sacral lengths were measured at this level. METHODS: The distribution of the measurements were evaluated to determine a medial and lateral safe zone, as well as the average nerve width at the level of S1 pedicle screw placement. Correlation analysis was performed to determine a relationship between safe zone sizes and sacral size. RESULTS: A total of 400 MRIs were analyzed. The average medial safe zone measured was 32.8 mm (95% CI: 32.2-33.4) with no nerves lying within 22.3 mm of the midline sacrum. The average lateral safe zone measured was 17.7 mm (95% CI: 17.1-18.2), with no nerves within 5.3 mm of the lateral border of the sacrum. The average nerve root width was 6.2 mm (95% CI: 6.13-6.34). An increased sacral length was associated with a larger medial (p<.001) and lateral (p<.001) safe zone. CONCLUSIONS: Our study revealed lateral and medial safe zones for the placement of S1 pedicle screws to avoid iatrogenic nerve injury in a retrospective cohort of 400 patients. There were no L5 nerve roots found within 22.3 mm of the sacrum's mid-axis or within 5.3 mm of the sacrum's anterolateral border. These defined safe zones can be used during pedicle screw planning and placement to decrease the risk of injury to the L5 nerve root.

Notch signaling enhances bone regeneration in the zebrafish mandible.

Loss or damage to the mandible caused by trauma, treatment of oral malignancies, and other diseases is treated using bone-grafting techniques that suffer from numerous shortcomings and contraindications. Zebrafish naturally heal large injuries to mandibular bone, offering an opportunity to understand how to boost intrinsic healing potential. Using a novel her6:mCherry Notch reporter, we show that canonical Notch signaling is induced during the initial stages of cartilage callus formation in both mesenchymal cells and chondrocytes following surgical mandibulectomy. We also show that modulation of Notch signaling during the initial post-operative period results in lasting changes to regenerate bone quantity one month later. Pharmacological inhibition of Notch signaling reduces the size of the cartilage callus and delays its conversion into bone, resulting in non-union. Conversely, conditional transgenic activation of Notch signaling accelerates conversion of the cartilage callus into bone, improving bone healing. Given the conserved functions of this pathway in bone repair across vertebrates, we propose that targeted activation of Notch signaling during the early phases of bone healing in mammals may both augment the size of the initial callus and boost its ossification into reparative bone.

Correction: Growing a backbone - functional biomaterials and structures for intervertebral disc (IVD) repair and regeneration: challenges, innovations, and future directions.

Correction for 'Growing a backbone - functional biomaterials and structures for intervertebral disc (IVD) repair and regeneration: challenges, innovations, and future directions' by Matthew D. Harmon et al., Biomater. Sci., 2020, 8, 1216-1239, DOI: .

Atomic force microscopy imaging for nanoscale and microscale assessments of extracellular matrix in intervertebral disc and degeneration.

Degeneration of the intervertebral disc (IVD) is a condition that is often associated with debilitating back pain. There are no disease-modifying treatments available to halt the progression of this ubiquitous disorder. This is partly due to a lack of understanding of extracellular matrix (ECM) changes that occur at the micro- and nanometer size scales as the disease progresses. Over the past decade, atomic force microscopy (AFM) has been utilized as a tool to investigate the impact of disease on nanoscale structure of ECM in bone, skin, tendon, and dentin. We have expanded this methodology to include the IVD and report the first quantitative analysis of ECM structure at submicron size scales in a murine model for progressive IVD degeneration. Collagen D-spacing, a metric of nanoscale structure at the fibril level, was observed as a distribution of values with an overall average value of 62.5 ± 2.5 nm. In degenerative discs, the fibril D-spacing distribution shifted towards higher values in both the annulus fibrosus and nucleus pulposus (NP) (P < .05). A novel microstructural feature, collagen toroids, defined by a topographical pit enclosed by fibril-forming matrix was observed in the NP. With degeneration, these microstructures became more numerous and the morphology was altered from circular (aspect ratio 1.0 ± 0.1) to oval (aspect ratio 1.5 ± 0.4), P < .005. These analyses provide ECM structural details of the IVD at size scales that have historically been missing in studies of disc degeneration. Knowledge gained from these insights may aid the development of novel disease-modifying therapeutics.