Can static optimization detect changes in peak medial knee contact forces induced by gait modifications?

Medial knee contact force (MCF) is related to the pathomechanics of medial knee osteoarthritis. However, MCF cannot be directly measured in the native knee, making it difficult for therapeutic gait modifications to target this metric. Static optimization, a musculoskeletal simulation technique, can estimate MCF, but there has been little work validating its ability to detect changes in MCF induced by gait modifications. In this study, we quantified the error in MCF estimates from static optimization compared to measurements from instrumented knee replacements during normal walking and seven different gait modifications. We then identified minimum magnitudes of simulated MCF changes for which static optimization correctly identified the direction of change (i.e., whether MCF increased or decreased) at least 70% of the time. A full-body musculoskeletal model with a multi-compartment knee and static optimization was used to estimate MCF. Simulations were evaluated using experimental data from three subjects with instrumented knee replacements who walked with various gait modifications for a total of 115 steps. Static optimization underpredicted the first peak (mean absolute error = 0.16 bodyweights) and overpredicted the second peak (mean absolute error = 0.31 bodyweights) of MCF. Average root mean square error in MCF over stance phase was 0.32 bodyweights. Static optimization detected the direction of change with at least 70% accuracy for early-stance reductions, late-stance reductions, and early-stance increases in peak MCF of at least 0.10 bodyweights. These results suggest that a static optimization approach accurately detects the direction of change in early-stance medial knee loading, potentially making it a valuable tool for evaluating the biomechanical efficacy of gait modifications for knee osteoarthritis.

Understanding the Patient Experience: Analysis of 2-Word Assessment and Its Relationship to Likelihood to Recommend in Outpatient Hand Surgery.

BACKGROUND: Actionable feedback from patients after a clinic visit can help inform ways to better deliver patient-centered care. A 2-word assessment may serve as a proxy for lengthy post-visit questionnaires. We tested the use of a 2-word assessment in an outpatient hand clinic. METHODS: New patients were asked to provide a 2-word assessment of the following: (1) their physician; (2) their overall experience; and (3) recommendations for improvement and their likelihood to recommend (LTR) after their clinic visit. Sentiment analysis was used to categorize results into positive, neutral, or negative sentiment. Recommendations for improvement were classified into physician issue, system issue, or neither. We evaluated the relationship between LTR status, sentiment, actionable improvement opportunities, and classification (physician issue, system issue, or neither). Recommendations for improvement were classified into themes based on prior literature. RESULTS: Sixty-seven (97.1%) patients noted positive sentiment toward their physician; 67 (97.1%) noted positive sentiment toward their overall experience. About 31% of improvement recommendations were system-based, 5.9% were physician-based, and 62.7% were neither. Patients not LTR were more likely to leave actionable opportunities for improvement than those LTR (P = .01). Recommendations for improvement were classified into predetermined themes relating to: (1) physician interaction; (2) check-in process; (3) facilities; (4) unnecessary visit; and (5) appointment delays. CONCLUSION: Patients not likely to recommend provided actionable opportunities for improvement using a simple 2-word assessment. Implementation of a 2-word assessment in a hand clinic can be used to obtain actionable, real-time patient feedback that can inform operational change and improve the patient experience.

Relationship between industry royalty and licensing payments and patent authorship among orthopedic spine surgeons.

BACKGROUND CONTEXT: The Physician Payments Sunshine Act requires manufacturers of drugs, medical devices, medical supplies, and biologics to record all financial relationships with physicians in the Open Payments database with the goal of increasing transparency for patients and the general public. The majority of total money going to orthopedic surgeons has been found to go to a small number of surgeons in the form of royalties and licensing payments. This category of payment is intended to compensate physicians for use of their intellectual property. However, little research has been done to investigate the degree to which these physicians own intellectual property. PURPOSE: To the authors' knowledge, the association between patents and industry payments to orthopedic surgeons has not been explored. We quantify the association between the patents and academic productivity of orthopedic spine surgeons and the amount of royalty and licensing fees they receive. We then compared this with the associations observed for other categories of payments. STUDY DESIGN: Cross-sectional study METHODS: Top royalty and licensing earners, defined as those who collectively earned 50% of all royalty and licensing payments over the period August 2013-December 2018, were identified. The h-index, publication count, and patent count of this group were compared with top earners of other payment categories using the Mann-Whitney U test. The association between (1) earnings and patent counts, (2) earnings and manuscript counts, and (3) earnings and h-index among the top royalty and licensing earners was assessed using Spearman correlation. RESULTS: Top royalty and licensing earners had significantly more patents than every comparison group except the top earners of money derived from ownership in a biomedical company. For this one exception, there was a trend toward the top eight royalty and licensing earners having more patents (p=.054). The top royalty and licensing earners had significantly more manuscripts than three of the five comparison groups and significantly higher h-indices than four of the five comparison groups. Among the top royalty and licensing earners, receiving more royalty and licensing payments was associated with holding more patents, but not with publishing more papers or having higher h-indices. CONCLUSIONS: There is a strong association between the number of patents authored by individual orthopedic spine surgeons and the amount of royalty and licensing fees they receive from industry. This supports the hypothesis that these payments serve as compensation to inventor-surgeons for their intellectual property. CLINICAL SIGNIFICANCE: Our findings provide new, important context for the largest category of industry payments to orthopedic spine surgeons and suggests that physicians' patents should be considered when evaluating financial transactions between industry and physicians.

Tendency of Driving to the Basket Is Associated With Increased Risk of Anterior Cruciate Ligament Tears in National Basketball Association Players: A Cohort Study.

BACKGROUND: Driving to the basket in basketball involves acceleration, deceleration, and lateral movements, which may expose players to increased anterior cruciate ligament (ACL) injury risk. It is unknown whether players who heavily rely on driving have decreased performance on returning to play after ACL reconstruction (ACLR). HYPOTHESIS: Players with a greater tendency to drive to the basket would be more likely to tear their ACL versus noninjured controls and would experience decreased performance when returning to play after ACLR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Season-level performance statistics and ACL injuries were aggregated for National Basketball Association (NBA) seasons between 1980 and 2017 from publicly available sources. Players' tendency to drive was calculated using 49 common season-level performance metrics. Each ACL-injured player was matched with 2 noninjured control players by age, league experience, and style of play metrics. Points, playing minutes, driving, and 3-point shooting tendencies were compared between players with ACL injuries and matched controls. Independent-samples t test was utilized for comparisons. RESULTS: Of 86 players with a total of 96 ACL tears identified in the NBA, 50 players were included in the final analysis. Players who experienced an ACL tear had a higher career-average drive tendency than controls (P = .047). Players with career-average drive tendency ≥1 standard deviation above the mean were more likely to tear their ACL than players with drive tendency <1 standard deviation (5.2% vs 2.7%; P = .026). There was no significant difference in total postinjury career points (P = .164) or career minutes (P = .237) between cases and controls. There was also no significant change in drive tendency (P = .152) or 3-point shooting tendency (P = .508) after return to sport compared with controls. CONCLUSION: NBA players with increased drive tendency were more likely to tear their ACL. However, players who were able to return after ACLR did not underperform compared with controls and did not alter their style of play compared with the normal changes seen with age. This information can be used to target players with certain playing styles for ACL injury prevention programs.

Open Source Software for Automatic Subregional Assessment of Knee Cartilage Degradation Using Quantitative T2 Relaxometry and Deep Learning.

OBJECTIVE: We evaluated a fully automated femoral cartilage segmentation model for measuring T2 relaxation values and longitudinal changes using multi-echo spin-echo (MESE) magnetic resonance imaging (MRI). We open sourced this model and developed a web app available at https://kl.stanford.edu into which users can drag and drop images to segment them automatically. DESIGN: We trained a neural network to segment femoral cartilage from MESE MRIs. Cartilage was divided into 12 subregions along medial-lateral, superficial-deep, and anterior-central-posterior boundaries. Subregional T2 values and four-year changes were calculated using a radiologist's segmentations (Reader 1) and the model's segmentations. These were compared using 28 held-out images. A subset of 14 images were also evaluated by a second expert (Reader 2) for comparison. RESULTS: Model segmentations agreed with Reader 1 segmentations with a Dice score of 0.85 ± 0.03. The model's estimated T2 values for individual subregions agreed with those of Reader 1 with an average Spearman correlation of 0.89 and average mean absolute error (MAE) of 1.34 ms. The model's estimated four-year change in T2 for individual subregions agreed with Reader 1 with an average correlation of 0.80 and average MAE of 1.72 ms. The model agreed with Reader 1 at least as closely as Reader 2 agreed with Reader 1 in terms of Dice score (0.85 vs. 0.75) and subregional T2 values. CONCLUSIONS: Assessments of cartilage health using our fully automated segmentation model agreed with those of an expert as closely as experts agreed with one another. This has the potential to accelerate osteoarthritis research.

Evaluation of the Rhizosphere Contribution to the Environmental Fate of the Herbicide Prometryn.

Plant protection products (PPPs) undergo rigorous regulatory assessment to ensure that they do not pose unacceptable risks to the environment. Elucidation of their fate and behavior in soil is an integral part of this environmental risk assessment. The active substance degradation in soil of PPPs is first assessed in laboratory studies (typically following Organisation for Economic Co-operation and Development [OECD] test guideline 307). Conditions in guideline laboratory studies are far removed from those occurring under agricultural use, and the contribution of crop roots has currently not been assessed. We integrated viable plant root systems, representative of 3 different crop types, into the OECD test guideline 307 design to assess their impact on the dissipation of the herbicide prometryn. Significantly faster decline of parent residue and higher formation of nonextractable residues were observed in all 3 planted systems. This led to a reduction in the time required for 50% of the compound to dissipate (DT50) of approximately one-half in the presence of rye grass and hot pepper and of approximately one-third in the presence of red clover. These findings imply that plants and their associated root networks can have a significant influence on PPP dissipation. Based on these data, greater environmental realism could be added to the standardized laboratory study design by the inclusion of plant root systems into higher tier studies, which, in turn, could serve to improve the environmental risk assessment process. Environ Toxicol Chem 2020;39:450-457. © 2019 SETAC.

Automated Classification of Radiographic Knee Osteoarthritis Severity Using Deep Neural Networks.

PURPOSE: To develop an automated model for staging knee osteoarthritis severity from radiographs and to compare its performance to that of musculoskeletal radiologists. MATERIALS AND METHODS: Radiographs from the Osteoarthritis Initiative staged by a radiologist committee using the Kellgren-Lawrence (KL) system were used. Before using the images as input to a convolutional neural network model, they were standardized and augmented automatically. The model was trained with 32 116 images, tuned with 4074 images, evaluated with a 4090-image test set, and compared to two individual radiologists using a 50-image test subset. Saliency maps were generated to reveal features used by the model to determine KL grades. RESULTS: With committee scores used as ground truth, the model had an average F1 score of 0.70 and an accuracy of 0.71 for the full test set. For the 50-image subset, the best individual radiologist had an average F1 score of 0.60 and an accuracy of 0.60; the model had an average F1 score of 0.64 and an accuracy of 0.66. Cohen weighted κ between the committee and model was 0.86, comparable to intraexpert repeatability. Saliency maps identified sites of osteophyte formation as influential to predictions. CONCLUSION: An end-to-end interpretable model that takes full radiographs as input and predicts KL scores with state-of-the-art accuracy, performs as well as musculoskeletal radiologists, and does not require manual image preprocessing was developed. Saliency maps suggest the model's predictions were based on clinically relevant information. Supplemental material is available for this article. © RSNA, 2020.

Differential requirements for COPI transport during vertebrate early development.

The coatomer vesicular coat complex is essential for normal Golgi and secretory activities in eukaryotic cells. Through positional cloning of genes controlling zebrafish notochord development, we found that the sneezy, happy, and dopey loci encode the alpha, beta, and beta' subunits of the coatomer complex. Export from mutant endoplasmic reticulum is blocked, Golgi structure is disrupted, and mutant embryos eventually degenerate due to widespread apoptosis. The early embryonic phenotype, however, demonstrates that despite its "housekeeping" functions, coatomer activity is specifically and cell autonomously required for normal chordamesoderm differentiation, perinotochordal basement membrane formation, and melanophore pigmentation. Hence, differential requirements for coatomer activity among embryonic tissues lead to tissue-specific developmental defects. Moreover, we note that the mRNA encoding alpha coatomer is strikingly upregulated in notochord progenitors, and we present data suggesting that alpha coatomer transcription is tuned to activity- and cell type-specific secretory loads.

Enhanced retention of polymer physical characteristics and mechanical strength of 70:30 poly(L-lactide-co-D,L-lactide) after ethylene oxide sterilization.

This study examined the effect of ethylene oxide (EtO) and electron beam (e-beam) irradiation on the properties of 70:30 poly(L-lactide-co-D,L-lactide). The effects of sterilization upon the polymer physical characteristics and strength retention of the material were examined, both initially and after being subjected to real time ageing. Commercially available 70:30 poly(L-lactide-co-D,L-lactide) material was fabricated into rectangular, cylindrical, screw, and sheet designs, and tested in compression, shear, or tension. Sterilization of 70:30 poly(L-lactide-co-D,L-lactide) by ethylene oxide had a nearly negligible effect on the physical properties of the polymer, regardless of specimen size or manufacturing technique. The molecular weight and inherent viscosity of the specimens decreased by approximately 3% after sterilization by EtO. However, sterilization of 70:30 poly(L-lactide-co-D,L-lactide) by e-beam irradiation resulted in immediate changes to some of the physical properties of the polymer. Specimens sterilized by e-beam irradiation displayed an immediate decrease in inherent viscosity of approximately 67% as compared to the respective nonsterile samples. The immediate decrease in inherent viscosity and molecular weight with e-beam irradiation required approximately 39 weeks of real time ageing of the EtO sterilized parts. At all time points investigated in the present study, the strength retention of the EtO sterilized devices equaled or exceeded that of the e-beam irradiated samples.

Characterization of a faster resorbing polymer after real time aging.

This study evaluated the in vitro strength retention and polymer characteristics of specimens made from commercially available 85:15 poly(D,L-lactide-co-glycolide). Test samples included dogbone tensile specimens with a nominal thickness of either 0.75 and 1.0 mm, which were machined from compression-molded sheets, and screws with a major diameter of 2.71 mm and minor diameter of 2.14 mm, which were manufactured by injection molding. All samples were sterilized by e-beam irradiation prior to in vitro aging following a standard methodology. Mechanical testing and polymer analysis were performed at time zero and weekly up to 15 weeks of real time aging. The time zero maximum tensile strength of the 0.75 mm dogbone specimens averaged 55.86 +/- 0.72 MPa. The 1.0-mm dogbone specimens tested at time zero had an average maximum tensile strength of 34.55 +/- 0.36 MPa. The 0.75-mm and 1.0-mm thick dogbone specimens exhibited a controlled decrease in their tensile strength. The initial shear strength of the injection-molded screws was 32.86 +/- 4.15 MPa. After 3 weeks of real time in vitro aging, the screws maintained approximately 70% of their initial (time zero) strength. The inherent viscosity and molecular weight (Mw) at time zero averaged approximately 0.9 dL/g and 98,000 g/mol respectively, and decreased at similar rates for both dogbones and screws. These results demonstrate a controlled, rapid degradation in the mechanical properties of 85:15 poly(D,L-lactide-co-glycolide) material, with sufficient strength for pediatric craniofacial applications.

Evaluation of a bioresorbable polylactide sheet for the reduction of pelvic soft tissue attachments in a porcine animal model.

In an adult porcine model, the effectiveness of a bioresorbable film to minimize soft tissue attachment to the pelvic viscera was evaluated at 4-week and 12-week endpoints. Following a transperitoneal laparotomy through a midline incision, the bladder and uterus were abraded in all animals to promote soft tissue attachment to the viscera. Control animals received no further treatment. The experimental group animals were treated with bioresorbable polylactide (PLa) sheets, 0.02 mm thick, one between the bladder and the abdominal wall, and a second sheet between the bladder and the uterus. Quantitative assessment of the severity and location of soft tissue attachments, and qualitative histologic assessment were performed at 4 and 12 weeks post-operatively. Statistically significant differences in the quantitative soft tissue attachment scores were observed in comparing the PLa film treated animals versus the control animals, at both the 4-week and 12-week time points. In the control animals, the formation of numerous thick fibrous bands was observed at both time points. Histology revealed no adverse reaction to the bioresorbable PLa barrier film. The bioresorbable PLa sheet provided an effective barrier between adjacent anatomical structures and minimized soft tissue attachments to the device when in contact with the viscera as compared to the control groups. Surgical dissection planes between the abdominal wall and adjacent soft tissues were maintained with the use of the PLa sheet at both time points.

Viscoelastic material properties of the peripapillary sclera in normal and early-glaucoma monkey eyes.

PURPOSE: To test the hypothesis that changes in the viscoelastic material properties of peripapillary sclera are present within monkey eyes at the onset of early experimental glaucoma detected by confocal scanning laser tomography (CSLT). METHODS: Short-term (3-9 weeks), moderate (< or =44 mm Hg) intraocular pressure (IOP) elevation was induced in one eye of each of eight male monkeys by lasering the trabecular meshwork. This procedure generated early experimental glaucoma, defined as the onset of CSLT-detected optic nerve head (ONH) surface change, in the treated eye. Scleral tensile specimens from the superior and inferior quadrants of the eight early-glaucoma eyes were subjected to uniaxial stress relaxation and tensile tests to failure and the results compared with similar data obtained in a previous study of 12 normal (nonglaucomatous) eyes. Linear viscoelastic theory was used to characterize viscoelastic material property parameters for each specimen. Differences in each parameter due to quadrant and treatment were assessed by analysis of variance (ANOVA). RESULTS: Peripapillary sclera from the early-glaucoma eyes exhibited an equilibrium modulus (7.46 +/- 1.58 MPa) that was significantly greater than that measured in normal eyes (4.94 +/- 1.22 MPa; mean +/- 95% confidence interval, P < 0.01, ANOVA). Quadrant differences were not significant for the viscoelastic parameters within each treatment group. CONCLUSIONS: The long-term viscoelastic material properties of monkey peripapillary sclera are altered by exposure to moderate, short-term, chronic IOP elevations and these alterations are present at the onset of CSLT-detected glaucomatous damage to the ONH. Damage to and/or remodeling of the extracellular matrix of these tissues may underlie these changes in scleral material properties.

Strength retention of 70:30 poly(L-lactide-co-D,L-lactide) following real-time aging.

This study evaluated the in vitro strength retention and polymer characteristics of plates and screws made from commercially available 70:30 poly(L-lactide-co-D,L-lactide) over a 2-year time period. Test samples included three routine manufacturing lots each of plates (1.2 mm thick, 41.70 mm long, with 2.5-mm holes), which were machined from compression-molded sheets, and screws (2.4-mm major diameter and 1.86-mm minor diameter), which were manufactured by injection molding. All samples were sterilized by e-beam irradiation prior to in vitro aging following a standard methodology. Mechanical testing and polymer analysis was performed after 0, 6, 13, 26, 39, 52, 65, 78, and 104 weeks. The initial (time zero) tensile strength of the plates averaged 33.2+/-1.9 MPa; the plates retained 100% of this strength at 6 weeks, 84% at 13 weeks, and 34% at 39 weeks. The screws had an initial (time zero) shear strength of 29.8+/-4.2 MPa, and maintained 97% of this strength at 26 weeks and 73% of this strength at 39 weeks. The inherent viscosity and molecular weight (M(w)) at time zero averaged approximately 1.4 dL/g and 165,000 g/mol, respectively, and decreased at similar rates for both the plates and screws. These results demonstrate excellent strength retention of devices fabricated from 70:30 poly(L-lactide-co-D,L-lactide) over time periods exceeding those associated with normal bone healing.

Use of a resorbable sheet in iliac crest reconstruction in a sheep model.

OBJECT: Iliac crest bone graft harvesting can result in major complications, the rates of which range from approximately 6 to 8%. The objective of this study was to evaluate the postoperative regeneration of iliac crest donor defects in an animal model after harvesting a full-thickness tricortical graft. METHODS: In skeletally mature sheep, a tricortical iliac crest graft was harvested. The graft sites were allowed to heal unprotected or protected with the resorbable polylactic acid sheet material, MacroPore OS Protective Sheeting. After 6 months of healing, the sites were assessed by examination of undecalcified histological sections. Histomorphometric measurements of the original defect area, the area of new bone within the defect site, and the percentage of defect filled with new bone were quantified for both control and protected groups. In all histological sections, new bone growth within the defect sites appeared normal, with no observed excessive inflammatory cells. The developing bone tissue appeared to be remodeling normally. For the unprotected sites, the area of new bone averaged 16.3 mm2 (+/- 7.2 mm2), and the percentage of the defect area filled with bone averaged 10.7% (+/- 6.5%). In the protected sites, the area of new bone averaged 64.8 mm2 (+/- 11.6 mm2) and the percentage of the defect area filled with bone averaged 25.9% (+/- 1.6%). Both differences in area of new bone growth and percentage of defect area filled were statistically significant. Literature review has indicated that regeneration of donor site defects is desirable. CONCLUSIONS: Based on the results of the present study, MacroPore resorbable Protective Sheeting can improve bone regeneration significantly within the donor site following tricortical iliac crest graft harvesting.

Use of polylactide resorbable film as an adhesion barrier.

OBJECT: The present investigation evaluates two thicknesses of a resorbable polylactic acid (PLA) barrier film as an adhesion barrier to posterior spinal scar formation. METHODS: A readily contourable, thin film was placed directly over the dura. The thick film was placed above the lamina defect to act as a physical barrier inhibiting the prolapse of soft tissue into the epidural space. Through a combination of gross dissection with and without scar scores, quantitative analysis of collagen adjacent to the scar site, and histological evaluation, the resorbable adhesion barrier membranes were found to be effective treatment for reduction of posterior adhesions. CONCLUSIONS: The gross dissection demonstrated that both thicknesses of resorbable PLA barrier films created a controlled dissection plane, facilitated access to the epidural space, and provided a reduction in the tissue adherent to the dura.

MacroPore resorbable devices in craniofacial surgery.

Resorbable polymer implants have become a compelling option in the treatment of acquired and congenital craniofacial deformities. The resorbable polylactide (PLa) and polyglycolide (PGa) polymers in particular have demonstrated excellent safety profile sin multiple in vitro, animal, and clinical studies and are currently being used in a wide variety of craniofacial applications. In this article, the authors discuss the biomaterial properties of PLa and PGa resorbable implants and provide an overview of the use of these polymers in craniofacial surgery. They conclude by relating their experience with an ongoing clinical series using MacroPore PLDLa and FRP implants for various applications,including Le Fort osteotomies, midface/monobloc internal distraction, and craniosynostosis reconstruction.

Use of a resorbable sheet in iliac crest reconstruction in a sheep model.

Iliac crest bone graft harvesting can result in major complications that occur at rates of approximately 6%-8%. The objective of this study was to evaluate the postoperative regeneration of iliac crest donor defects in an animal model after harvesting a full-thickness tricortical graft. In skeletally mature sheep, a tricortical iliac crest graft was harvested. The graft sites were allowed to heal nonprotected or protected with the resorbable polylactic acid sheet material, MacroPore OS Protective Sheeting, (MacroPore Biosurgery, San Diego, Calif). After 6 months of healing, the sites were assessed by examination of undecalcified histologic sections. Histomorphometric measurements of the original defect area, the area of new bone within the defect site, and the percentage of defect filled with new bone were quantified for both control and protected groups. In all histologic sections, new bone growth within the defect sites appeared normal, with no excessive inflammatory cells observed. The developing bone tissue appeared to be remodeling normally. For the nonprotected sites, the area of new bone averaged 16.3 mm2 (+/-7.2 mm2), and the percentage of the defect area filled with bone averaged 10.7% (+/-6.5%). In the protected sites, the area of new bone averaged 64.8 mm2 (+/-11.6 mm2) and the percentage of the defect area filled with bone averaged 25.9% (+/-1.6%). Both differences in area of new bone growth and percentage of defect area filled were statistically significant. Literature review has indicated that regeneration of donor site defects is desirable. Based upon the results of the present study, MacroPore resorbable protective sheeting can improve bone regeneration significantly within the donor site following tricortical iliac crest graft harvesting.

Use of polylactide resorbable film as an adhesion barrier.

The present investigation evaluates two thicknesses of a resorbable polylactide barrier film as an adhesion barrier to posterior spine scar formation. A readily contourable, thin film was placed directly over the dura. The thick film was placed above the lamina defect to act as a physical barrier inhibiting the prolapse of soft tissue into the epidural space. Through a combination of gross dissection with and without scar scores, quantitative analysis of collagen adjacent to the scar site, and histologic evaluation, the resorbable adhesion barrier membranes were found to be effective treatment for reduction of posterior adhesions. The gross dissection demonstrated that both thicknesses of resorbable polymer barrier films created a controlled dissection plane, facilitated access to the epidural space, and provided a reduction in the tissue adhered to the dura.