Towards an AI-Based Objective Prognostic Model for Quantifying Wound Healing.

Chronic wounds affect millions of people worldwide every year. An adequate assessment of a wound's prognosis is critical to wound care, guiding clinical decision making by helping clinicians understand wound healing status, severity, triaging and determining the efficacy of a treatment regimen. The current standard of care involves using wound assessment tools, such as Pressure Ulcer Scale for Healing (PUSH) and Bates-Jensen Wound Assessment Tool (BWAT), to determine wound prognosis. However, these tools involve manual assessment of a multitude of wound characteristics and skilled consideration of a variety of factors, thus, making wound prognosis a slow process which is prone to misinterpretation and high degree of variability. Therefore, in this work we have explored the viability of replacing subjective clinical information with deep learning-based objective features derived from wound images, pertaining to wound area and tissue amounts. These objective features were used to train prognostic models that quantified the risk of delayed wound healing, using a dataset consisting of 2.1 million wound evaluations derived from more than 200,000 wounds. The objective model, which was trained exclusively using image-based objective features, achieved at minimum a 5% and 9% improvement over PUSH and BWAT, respectively. Our best performing model, that used both subjective and objective features, achieved at minimum an 8% and 13% improvement over PUSH and BWAT, respectively. Moreover, the reported models consistently outperformed the standard tools across various clinical settings, wound etiologies, sexes, age groups and wound ages, thus establishing the generalizability of the models.

Comparison of wound surface area measurements obtained using clinically validated artificial intelligence-based technology versus manual methods and the effect of measurement method on debridement code reimbursement cost.

BACKGROUND: Evidence shows that ongoing accurate wound assessments using valid and reliable measurement methods is essential to effective wound monitoring and better wound care management. Relying on subjective interpretation in measuring wound dimensions and assuming a rectilinear shape of all wounds renders an inconsistent and inaccurate wound area measurement. OBJECTIVE: The authors investigated the discrepancy in wound area measurements using a DWMS versus TPR methods and compared debridement codes submitted for reimbursement by assessment method. METHODS: The width and length of 177 wounds in 56 patients were measured at an outpatient clinic in the United States using the TPR method (width × length formula) and a DWMS (traced wound dimensions). The maximal allowable payment for debridement was calculated for both methods using the reported CPT codes based on each 20-cm2 estimated surface area. RESULTS: The average wound surface area was significantly higher with the TPR method than with the DWMS (20.20 and 12.81, respectively; P = .025). For patients with dark skin tones, ill-defined wound edges, irregular wound shapes, unhealthy tissues, and the presence of necrotic tissues, the use of the DWMS resulted in significantly lower mean differences in wound area measurements of 14.4 cm2 (P < .008), 8.2 cm2 (P = .040), 6.8 cm2 (P = .045), 13.1 cm2 (P = .036), and 7.6 cm2 (P = .043), respectively, compared with the TPR method. Use of the DWMS for wound surface area measurement resulted in a 10.6% lower reimbursement amount for debridement, with 82 fewer submitted codes, compared with the TPR method. CONCLUSIONS: Compared with the DWMS, TPR measurements overestimated wound area more than 36.6%. This overestimation was associated with dark skin tones and wounds with irregular edges, irregular shapes, and necrotic tissue.

Is my wound infected? A study on the use of hyperspectral imaging to assess wound infection.

Introduction: Clinical signs and symptoms (CSS) of infection are a standard part of wound care, yet they can have low specificity and sensitivity, which can further vary due to clinician knowledge, experience, and education. Wound photography is becoming more widely adopted to support wound care. Thermography has been studied in the medical literature to assess signs of perfusion and inflammation for decades. Bacterial fluorescence has recently emerged as a valuable tool to detect a high bacterial load within wounds. Combining these modalities offers a potential objective screening tool for wound infection. Methods: A multi-center prospective study of 66 outpatient wound care patients used hyperspectral imaging to collect visible light, thermography, and bacterial fluorescence images. Wounds were assessed and screened using the International Wound Infection Institute (IWII) checklist for CSS of infection. Principal component analysis was performed on the images to identify wounds presenting as infected, inflamed, or non-infected. Results: The model could accurately predict all three wound classes (infected, inflamed, and non-infected) with an accuracy of 74%. They performed best on infected wounds (100% sensitivity and 91% specificity) compared to non-inflamed (sensitivity 94%, specificity 70%) and inflamed wounds (85% sensitivity, 77% specificity). Discussion: Combining multiple imaging modalities enables the application of models to improve wound assessment. Infection detection by CSS is vulnerable to subjective interpretation and variability based on clinicians' education and skills. Enabling clinicians to use point-of-care hyperspectral imaging may allow earlier infection detection and intervention, possibly preventing delays in wound healing and minimizing adverse events.

Diagnostic reliability in teledermatology: a systematic review and a meta-analysis.

OBJECTIVES: To compare teledermatology and face-to-face (F2F) agreement in primary diagnoses of dermatological conditions. DESIGN: Systematic review and meta-analysis METHODS: MEDLINE, Embase, Cochrane Library (Wiley), CINAHL and medRxiv were searched between January 2010 and May 2022. Observational studies and randomised clinical trials that reported percentage agreement or kappa concordance for primary diagnoses between teledermatology and F2F physicians were included. Titles, abstracts and full-text articles were screened in duplicate. From 7173 citations, 44 articles were included. A random-effects meta-analysis was conducted to estimate pooled estimates. Primary outcome measures were mean percentage and kappa concordance for assessing diagnostic matches between teledermatology and F2F physicians. Secondary outcome measures included the agreement between teledermatologists, F2F dermatologists, and teledermatology and histopathology results. RESULTS: 44 studies were extracted and reviewed. The pooled agreement rate was 68.9%, and kappa concordance was 0.67. When dermatologists conducted F2F and teledermatology consults, the overall diagnostic agreement was significantly higher at 71% compared with 44% for non-specialists. Kappa concordance was 0.69 for teledermatologist versus specialist and 0.52 for non-specialists. Higher diagnostic agreements were also noted with image acquisition training and digital photography. The agreement rate was 76.4% between teledermatologists, 82.4% between F2F physicians and 55.7% between teledermatology and histopathology. CONCLUSIONS AND RELEVANCE: Teledermatology can be an attractive option particularly in resource-poor settings. Future efforts should be placed on incorporating image acquisition training and access to high-quality imaging technologies. TRIAL REGISTRATION NUMBER: 10.17605/OSF.IO/FJDVG.

A time motion study of manual versus artificial intelligence methods for wound assessment.

OBJECTIVES: This time-motion study explored the amount of time clinicians spent on wound assessments in a real-world environment using wound assessment digital application utilizing Artificial Intelligence (AI) vs. manual methods. The study also aimed at comparing the proportion of captured quality wound images on the first attempt by the assessment method. METHODS: Clinicians practicing at Valley Wound Center who agreed to join the study were asked to record the time needed to complete wound assessment activities for patients with active wounds referred for a routine evaluation on the follow-up days at the clinic. Assessment activities included: labelling wounds, capturing images, measuring wounds, calculating surface areas, and transferring data into the patient's record. RESULTS: A total of 91 patients with 115 wounds were assessed. The average time to capture and access wound image with the AI digital tool was significantly faster than a standard digital camera with an average of 62 seconds (P<0.001). The digital application was significantly faster by 77% at accurately measuring and calculating the wound surface area with an average of 45.05 seconds (P<0.001). Overall, the average time to complete a wound assessment using Swift was significantly faster by 79%. Using the AI application, the staff completed all steps in about half of the time (54%) normally spent on manual wound evaluation activities. Moreover, acquiring acceptable wound image was significantly more likely to be achieved the first time using the digital tool than the manual methods (92.2% vs. 75.7%, P<0.004). CONCLUSIONS: Using the digital assessment tool saved significant time for clinicians in assessing wounds. It also successfully captured quality wound images at the first attempt.

Fully Automated Wound Tissue Segmentation Using Deep Learning on Mobile Devices: Cohort Study.

BACKGROUND: Composition of tissue types within a wound is a useful indicator of its healing progression. Tissue composition is clinically used in wound healing tools (eg, Bates-Jensen Wound Assessment Tool) to assess risk and recommend treatment. However, wound tissue identification and the estimation of their relative composition is highly subjective. Consequently, incorrect assessments could be reported, leading to downstream impacts including inappropriate dressing selection, failure to identify wounds at risk of not healing, or failure to make appropriate referrals to specialists. OBJECTIVE: This study aimed to measure inter- and intrarater variability in manual tissue segmentation and quantification among a cohort of wound care clinicians and determine if an objective assessment of tissue types (ie, size and amount) can be achieved using deep neural networks. METHODS: A data set of 58 anonymized wound images of various types of chronic wounds from Swift Medical's Wound Database was used to conduct the inter- and intrarater agreement study. The data set was split into 3 subsets with 50% overlap between subsets to measure intrarater agreement. In this study, 4 different tissue types (epithelial, granulation, slough, and eschar) within the wound bed were independently labeled by the 5 wound clinicians at 1-week intervals using a browser-based image annotation tool. In addition, 2 deep convolutional neural network architectures were developed for wound segmentation and tissue segmentation and were used in sequence in the workflow. These models were trained using 465,187 and 17,000 image-label pairs, respectively. This is the largest and most diverse reported data set used for training deep learning models for wound and wound tissue segmentation. The resulting models offer robust performance in diverse imaging conditions, are unbiased toward skin tones, and could execute in near real time on mobile devices. RESULTS: A poor to moderate interrater agreement in identifying tissue types in chronic wound images was reported. A very poor Krippendorff α value of .014 for interrater variability when identifying epithelization was observed, whereas granulation was most consistently identified by the clinicians. The intrarater intraclass correlation (3,1), however, indicates that raters were relatively consistent when labeling the same image multiple times over a period. Our deep learning models achieved a mean intersection over union of 0.8644 and 0.7192 for wound and tissue segmentation, respectively. A cohort of wound clinicians, by consensus, rated 91% (53/58) of the tissue segmentation results to be between fair and good in terms of tissue identification and segmentation quality. CONCLUSIONS: The interrater agreement study validates that clinicians exhibit considerable variability when identifying and visually estimating wound tissue proportion. The proposed deep learning technique provides objective tissue identification and measurements to assist clinicians in documenting the wound more accurately and could have a significant impact on wound care when deployed at scale.

Infrared Thermography in Wound Care, Surgery, and Sports Medicine: A Review.

For many years, the role of thermometry was limited to systemic (core body temperature) measurements (e.g., pulmonary catheter) or its approximation using skin/mucosa (e.g., axillary, oral, or rectal) temperature measurements. With recent advances in material science and technology, thermal measurements went beyond core body temperature measurements and found their way in many medical specialties. The article consists of two primary parts. In the first part we overviewed current clinical thermal measurement technologies across two dimensions: (a) direct vs. indirect and (b) single-point vs. multiple-point temperature measurements. In the second part, we focus primarily on clinical applications in wound care, surgery, and sports medicine. The primary focus here is the thermographic imaging modality. However, other thermal modalities are included where relevant for these clinical applications. The literature review identified two primary use scenarios for thermographic imaging: inflammation-based and perfusion-based. These scenarios rely on local (topical) temperature measurements, which are different from systemic (core body temperature) measurements. Quantifying these types of diseases benefits from thermographic imaging of an area in contrast to single-point measurements. The wide adoption of the technology would be accelerated by larger studies supporting the clinical utility of thermography.

A 57-Year-Old Man with Type 1 Diabetes Mellitus and a Chronic Foot Ulcer Successfully Managed with a Remote Patient-Facing Wound Care Smartphone Application.

BACKGROUND Wounds affect millions of people world-wide, with care being costly and difficult to deliver remotely. The ongoing COVID-19 pandemic highlights the urgent need for telehealth solutions to play a larger role as part of remote care strategies for patient monitoring and care. We describe our findings on the use of a patient-facing wound care app (Swift Patient Connect App, Swift Medical, Canada) as an innovative solution in remote wound assessment and management of a diabetic patient's wound. CASE REPORT In February 2020, a 57-year-old man with type I diabetes and peripheral arterial disease presented with osteomyelitis in the left foot at the fifth metatarsal, arising from a chronic ulcer. The wound was deep, with purulent discharge and polymicrobial growth. A 6-week course of intravenous antibiotics was administered, with slow improvement of the wound. At a follow-up appointment in June 2020, The Patient Connect app was recommended to the patient to securely share calibrated images of his wound as well to communicate with his doctor. Between June 2020 and January 2021, wound closure was accurately monitored as part of the management of this diabetic foot infection. The app was also used in the management of 2 subsequent wounds and infection episodes. CONCLUSIONS Use of the Swift Patient Connect App designed to monitor and manage wounds by a patient with diabetes and foot ulcer as part of a remote care strategy resulted in numerous benefits expressed by the patient. After initial adoption, 3 successive wounds were managed with a combination of in-person and telehealth visits complemented by the app. Incorporation of this technology as part of a novel telemedicine strategy promises to have an extensive impact on remote care delivery during the current COVID-19 pandemic and beyond.

Degenerative spondylolisthesis: a prospective cross-sectional cohort study on the role of weakened anterior abdominal musculature on causation.

PURPOSE: Degenerative spondylolisthesis (DS) is a degenerative condition of the spine which, unlike others, is more common in a female population. Previous studies have highlighted possible causative factors such as facet tropism and pregnancy as reasons for this. This study sets out to assess the possible link between abdominal musculature and DS. METHOD: A prospective cross-sectional cohort study in a single surgeon practice assessed all patients aged over 50 years attending for degenerative lumbar spinal complaints. Patient demographics, as well as the number of pregnancies, children, abdominal surgical procedures, were recorded. RESULTS: We found 205 patients that met our inclusion criteria (98 Males/107 Females). Women with multiple pregnancies (p = 0.036) and abdominal surgeries (p = 0.021) were more likely to develop DS. Males with ventral hernias were more likely to have developed DS (p = 0.004). CONCLUSION: This study highlights the important role that the abdominal musculature plays in stabilization of the spine and highlights its potential role as a factor in the development of DS. These slides can be retrieved under Electronic Supplementary Material.

Ten-year survival and clinical outcome of the AcroFlex lumbar disc replacement for the treatment of symptomatic disc degeneration.

BACKGROUND CONTEXT: We have previously reported on the osseointegration, stability, and preserved motion of the AcroFlex lumbar disc replacement (LDR) in a nonhuman primate model. Detailed biomechanical testing of the device predicted implant survival for at least 10 years of in vivo use. Significant improvements in the clinical outcome were reported at 2 years. However, mechanical failure of the polyolefin rubber was detected by fine-cut computed tomography (CT) in a number of subjects within 2 years. As a result, no further devices were implanted. PURPOSE: To report on the 10-year survival and clinical outcome of the AcroFlex elastomeric LDR when used for the treatment of one- or two-level symptomatic disc degeneration between L4 and S1. STUDY DESIGN: Prospective nonrandomized clinical trial with a mean 10-year follow-up. PATIENT SAMPLE: Twenty-eight patients with symptomatic disc degeneration who underwent AcroFlex LDR at one or two levels. OUTCOME MEASURES: Clinical: Visual Analog Score for back pain, Oswestry Disability Index (ODI), Low Back Outcome Score (LBOS), and Short Form-36 (SF-36). Survival: Kaplan-Meier analysis over 10 years with first revision surgery as the end point. Radiographic: Dynamic flexion/extension radiographs at 2 years. Magnetic resonance imaging (MRI) and CT scans at 10 years. METHODS: Twenty-eight subjects (14 male, mean age 41 years) with symptomatic disc degeneration unresponsive to nonsurgical treatment were enrolled into a prospective nonrandomized trial of the AcroFlex LDR. Visual analog score for back pain, ODI, LBOS, and SF-36 questionnaires were administered preoperatively at 6 months, 1, 2, and 10 years after the index procedure. All subjects were invited to undergo an MRI and for those with the device remaining in situ, a lumbar CT scan. Kaplan-Meier survival analysis was performed with first revision surgery as the end point. RESULTS: At a mean of 9 years, 8 months (range, 8 years, 8 months-11 years, 3 months) after surgery, 17 of 28 patients did not require a revision surgery, representing a cumulative survival of 60.7%. In contrast, 11 of 28 patients (39.3%) underwent a total of 14 revision procedures; 9 of 11 patients underwent a conversion to anterior lumbar interbody fusion supplemented with pedicle screw fixation. Indications for a revision included device failure in seven and disabling pain in four patients. Mean time to revision was 3 years, 10 months (range, 23 months-8 years, 4 months). Mean ODI at 10 years for nonrevision cases was 27.5 (±17.6) compared with 41.8 (±26) for revision cases. Mean improvement over 10 years in the ODI for nonrevision cases was 17.9 (±16.9) compared with 12 (±16.1) for revision cases. Similar trends were observed in LBOS and SF-36 scores. Radiographic findings in the revision group included midsubstance tears in the rubber, osteolysis, and implant displacement. CT findings in 11 of 17 survivors included heterotopic bone formation (85%), osteolysis (50%), and subsidence (14%). Magnetic resonance imaging in 14 of 23 subjects at the final follow-up demonstrated an adjacent-level disc degeneration in 68% of those with the AcroFlex LDR in situ and in 40% of those who had been converted to fusion. Skip-level disc degeneration was present in 44% of those with AcroFlex device in situ and in 20% of those who had been converted to fusion. CONCLUSIONS: The cumulative survival was 60.7% at 10 years when the first revision surgery was taken as the end point. The etiology of the implant failure prompting the revision included failure of osseointegration, midsubstance elastomeric tears, and osteolysis. Further use of this implant is not justified. The incidence of adjacent-level disc degeneration for the AcroFlex was comparable with that observed adjacent to the spinal fusion. Salvage procedures involving conversion to spinal fusion are technically demanding, but appear to improve outcomes modestly.

Something is amiss.

Commentary on: Cao P, Jiang L, Zhuang C, et al. Intradiscal injection therapy for degenerative chronic discogenic low back pain with end plate Modic changes. Spine J 2011:11:100-106 (in this issue).

Innervation of anulus tears: an experimental animal study.

STUDY DESIGN: A prospective immunohistological study in an animal model. OBJECTIVE: To identify and describe the phenotype of neoinnervation in experimental anular tears. SUMMARY OF BACKGROUND DATA: Controversy surrounds neoinnervation of degenerate discs which has been proposed as the anatomic basis for discogenic pain. Ablation of neoinnervation has been postulated as the theoretical basis for the claimed successes of procedures such as intradiscal electrotherapy. The animal model of disc degeneration previously developed in our research center provides an opportunity to investigate the innervation of anular tears in an extensively characterized lesion. METHODS: A surgical anular tear was created in 5 lumbar discs in 11 sheep which were killed at 1, 2, 3, and 12 months. Each spine was x-rayed and divided into motion segments for histologic analysis. Serial sections through the tear were immunostained for protein gene product 9.5, tyrosine hydroxylase, and calcitonin gene receptor protein. RESULTS: Neoinnervation of the periphery of the anular tear was observed. Ingrowing nerves penetrated marginally deeper than the normal anular innervation but no nerves were identified in the inner anulus or nucleus. A minority of the new axons were calcitonin gene receptor protein or tyrosine hydroxylase positive. CONCLUSION: The anulus tears in this model are innervated only peripherally to a depth only marginally greater than that of the normal anulus.

The prevalence and pathogenesis of synovial cysts within the ligamentum flavum in patients with lumbar spinal stenosis and radiculopathy.

STUDY DESIGN: A clinicopathologic study of synovial cysts in the ligamentum flavum (LF) in patients with spinal stenosis. OBJECTIVE: To investigate the pathogenesis of lumbar juxtafacet cysts. SUMMARY OF BACKGROUND DATA: Contradictions in the terminology applied to lumbar juxtafacet cysts arise from the frequent sparsity of synovial lining cells, which has led to synovial cysts often being called "ganglion cysts" despite lacking confirmatory pathology. METHODS: A total of 27 consecutive patients with radiologically confirmed stenosis underwent laminectomy. LF/facet joint (FJ) relationships were retained by en bloc excision of the LF and the medial inferior FJ. Controls were LF/FJ specimens from 47 cadaver lumbar spines. RESULTS: The 27 patients yielded 51 LF/FJ specimens containing 28 synovial cysts, 12 of which were unilateral and 8 were bilateral. Fragments of articular cartilage and bone were embedded in the walls of 89% of cysts and in the walls of a bursa-like channel originating from the medial aspect of the FJ capsule and extending into the LF. Communication with the FJ via this channel was observed in 21 (75%) of the 28 synovial cysts. Extending up to 12 mm in length, the channel was present in nearly all control spines at the L4-L5 level but in only about half at the T12-L1 level. CONCLUSION: Cysts having an extensive or meagre synovial cell lining are common in the LF of patients with symptomatic lateral or central stenosis. The cysts communicate with the FJ by a bursa-type channel within the LF. Advanced osteoarthritis of the FJ causes the liberation of fragments of cartilage and bone into the synovial fluid of the joint space. This enables some fragments to escape from the joint into the channel and become lodged within its wall where they provoke granulation tissue and scar formation. The tissue response to articular debris may block the synovial-lined channel to cause synovial cyst formation.

The natural history of age-related disc degeneration: the influence of age and pathology on cell populations in the L4-L5 disc.

STUDY DESIGN: A study of the density of cells in the L4-L5 disc during aging and in the presence of major pathology. OBJECTIVE: To quantify the density of cells throughout well-preserved adult L4-L5 discs and in discs containing major pathology. SUMMARY OF BACKGROUND DATA: The few and limited studies of disc have largely been part of biochemical studies having a major focus on disc nutrition. Excluding the cartilage end plate, the density of healthy cells in the disc is much lower than that of most body tissues. METHOD: The nucleus zone and 18 annulus zones were demarcated by inking the coverslips of hematoxylin-eosin-stained 5-mum thick sagittal sections of the L4-L5 disc. In each of the 19 zones, the healthy disc cells were enumerated in 10 randomly selected nonoverlapping high-power microscope fields. RESULTS: Assessment of the spatial cellularity in a disc divided into 7 parasagittal sections showed that the average density in the posterior annulus was significantly greater than that in the anterior annulus; the average density in the right half of the disc, including the nucleus, was significantly higher than that in the left and lowest in the left anterior quadrant. Studies of midsagittal sections from the spines of 10 men and 10 women, aged 13 to 78 years, showed that nuclear cellularity declined progressively throughout life, whereas that of the annulus ceased to decline after the age of 50 years. Some tears were associated with low cellularity close to the tear but not elsewhere, whereas extensive end-plate separations showed global reductions in cellularity. CONCLUSION: Disc cellularity declines as age advances and is reduced in the vicinity of major tears. Extensive end-plate abnormalities reduce cellularity by impeding disc nutrition.

Recent advances in annular pathobiology provide insights into rim-lesion mediated intervertebral disc degeneration and potential new approaches to annular repair strategies.

The objective of this study was to assess the impact of a landmark annular lesion model on our understanding of the etiopathogenesis of IVD degeneration and to appraise current IVD repairative strategies. A number of studies have utilised the Osti sheep model since its development in 1990. The experimental questions posed at that time are covered in this review, as are significant recent advances in annular repair strategies. The ovine model has provided important spatial and temporal insights into the longitudinal development of annular lesions and how they impact on other discal and paradiscal components such as the NP, cartilaginous end plates, zygapophyseal joints and vertebral bone and blood vessels. Important recent advances have been made in biomatrix design for IVD repair and in the oriented and dynamic culture of annular fibrochondrocytes into planar, spatially relevant, annular type structures. The development of hyaluronan hydrogels capable of rapid in situ gelation offer the possibility of supplementation of matrices with cells and other biomimetics and represent a significant advance in biopolymer design. New generation biological glues and self-curing acrylic formulations which may be augmented with slow delivery biomimetics in microcarriers may also find application in the non-surgical repair of annular defects. Despite major advances, significant technical challenges still have to be overcome before the biological repair of this intractable connective tissue becomes a realistic alternative to conventional surgical intervention for the treatment of chronic degenerate IVDs.

The biologic response to particles from a potential disc prosthesis material.

STUDY DESIGN: An in vivo study of material from a potential disc prosthesis. OBJECTIVE: To examine the histopathologic effect of particulate debris on the dura and neural tissue in sheep. SUMMARY OF BACKGROUND DATA: Disc prostheses are emerging as alternatives to spinal fusion for the treatment of symptomatic degenerative lumbar disc disease. Preclinical biocompatibility trials must be conducted before any device is considered for general use. METHODS: Artificially generated wear particles of a material known as Sinux (DePuy Spine, Raynham, MA) were implanted directly onto the lumbosacral dura and nerve roots of 18 sheep that were randomly allocated to 3 groups to survive between 1 and 6 months. Tissue sections from T12 to the sacrum were examined for histopathological evidence of inflammation and wound healing in response to the particles and for the effects on the neural elements. RESULTS: There was no significant evidence of inflammation, macrophage accumulation, or other tissue response. Other observations included some minor tissue pigmentation due to microhemorrhage, occasional but minimal lymphocyte infiltration, and crystalline Sinux in the fibroadipose connective tissue external to the dura. CONCLUSION: Artificially generated particles of Sinux placed directly onto the dura and nerve roots did not induce any significant biologic response in a sheep model.

The natural history of age-related disc degeneration: the pathology and sequelae of tears.

STUDY DESIGN: A quasi 3-dimensional pathologic survey of tears in the L4-L5 disc. OBJECTIVE: To seek accurate information on the pathogenesis and outcomes of tears to facilitate correlation with radiologic imaging and biomechanical testing; and to improve laboratory models for testing hypotheses of disc function and failure. SUMMARY OF BACKGROUND DATA: Tears are evidence of structural failure involving the anulus. There are substantial differences in the structure and function of the anterior and posterior anulus and the nonlamellar "nucleus" is much smaller than generally conceptualized and modeled. METHOD: Microscopy of sections prepared from 5-mm-thick parallel sagittal slices of 70 L4-L5 discs was used to construct maps of tears in each slice and record other features of interest. A template was used to classify data for analysis. RESULTS: Multiple-level analysis detected 20% more tears than in a single disc section. Concentric, perinuclear, and radiating tears often appeared first in the posterior disc and were numerous throughout life. However, rim lesions, transdiscal tears, endplate separations, and Schmorl's nodes were infrequent in young discs. Rim lesions and transdiscal tears markedly increased in the older discs while the other tears showed modest growth. In elderly discs, many tears acquired blood vessels accompanied by nerves capable of transmitting pain. Apart from about 15% of rim lesions, healing of tears by scar tissue was absent. Links between various types of tears result in complex discographic images from older discs and the cavitation of transdiscal tears lead to segmental instability. CONCLUSION: Tears in the L4-L5 disc show different patterns of incidence with aging, which can be explained by current biomechanical concepts. Tears may not only perturb disc function and cause segmental instability, but the frequency of neovascularization accompanied by neoinnervation indicates that pain originating within the degenerate disc should not be dismissed as the frequent evidence of bleeding into the tear lumen indicates the susceptibility of the vessels to trauma.

The International Society for the Study of the Lumbar Spine: research trends over time and publication rates.

STUDY DESIGN AND OBJECTIVES: A retrospective review was conducted to assess trends in research selected for podium presentation at ISSLS. SUMMARY OF BACKGROUND DATA: Abstracts of past papers presented to ISSLS provide quantified documentation of trends in research as well as insight into future directions. METHODS: A systematic review of abstracts of research presented was performed. Graphical plots in each category of research and aspects of study quality were used to identify any trends. Univariate and multivariate logistical regression analyses were used to identify factors related to eventual publication. RESULTS: A total of 43% of selected papers focused on the disc, representing the single largest area of research. There is a linear trend over time toward increased selection of basic science papers and decreased clinical papers. Experimental research design is becoming more frequently selected. In 1978, over 80% of papers were purely descriptive. By 2002, 42% of papers were descriptive, whereas 40% incorporated an experimental design. However, over the past decade, there has been a linear increase in the proportion of randomized controlled trials among clinical papers compared with basic science or biomechanical papers. A total of 54% of all abstracts presented recently went on to publication. Independent factors that were associated with significantly (P < 0.05) higher publication rates included use of blinded or independent observers (84.6%), experimental design (68.4%), basic science or biomechanical papers (62.3%), and statistically positive result (61.8%). CONCLUSION: Overall, the type of research selected for presentation at ISSLS has improved over the years in regards to greater use of experimental and randomized study design. The eventual publication rates compare favorably to other research societies. Factors related to publication have been identified and should be considered in future research.

Magnetic resonance imaging 20 years after anterior lumbar interbody fusion.

STUDY DESIGN: A 20-year magnetic resonance imaging (MRI) and functional outcome follow-up study was performed on patients who had undergone anterior lumbar interbody fusion. OBJECTIVES: The objectives of the present study are to determine whether or not degeneration is related to adjacent level fusion and the clinical significance of this degeneration. SUMMARY OF BACKGROUND DATA: There are concerns that lumbar fusion leads to increase stress at the adjacent levels. However, the clinical significance of this remains unclear. METHODS: Thirty-nine patients who underwent lower lumbar anterior lumbar interbody fusion and who had normal preoperative discograms at the level adjacent level were evaluated with a minimum of a 20-year follow-up. MRI scans were performed and independently evaluated for any evidence of degeneration. Functional status was assessed using the Low Back Outcome Scale. RESULTS: Twenty-nine (74.3%) patients had some evidence of degeneration in their lumbar spine and advanced degeneration was identified in 12 (30.7%) patients. Nine (23.1%) patients had advanced degeneration isolated to the adjacent level and 7 (17.9%) patients had evidence of advanced degeneration with preservation at the level adjacent to the fusion. There was no association between function and radiographic degeneration. Only 3 patients required additional surgery as a result of adjacent level degeneration. CONCLUSION: The prevalence of degenerative changes is similar to other studies involving normal asymptomatic subjects. Furthermore, the majority of degenerative changes seen occurred over multiple levels or at levels not adjacent to the fusion, suggesting that changes seen may be more likely related to constitutional factors as opposed to the increased stresses arising from the original fusion.