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Berger MB, Cohen DJ, Bosh KB, Kapitanov M, Slosar PJ, Levit MM, Gallagher M, Rawlinson JJ, Schwartz Z, Boyan BD. Bone marrow stromal cells generate an osteoinductive microenvironment when cultured on titanium-aluminum-vanadium substrates with biomimetic multiscale surface roughness. Biomed Mater 2023; 18. [PMID: 36827708 PMCID: PMC9993812 DOI: 10.1088/1748-605x/acbf15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 02/24/2023] [Indexed: 02/26/2023]
Abstract
Osseointegration of titanium-based implants possessing complex macroscale/microscale/mesoscale/nanoscale (multiscale) topographies support a direct and functional connection with native bone tissue by promoting recruitment, attachment and osteoblastic differentiation of bone marrow stromal cells (MSCs). Recent studies show that the MSCs on these surfaces produce factors, including bone morphogenetic protein 2 (BMP2) that can cause MSCs not on the surface to undergo osteoblast differentiation, suggesting they may produce an osteogenic environmentin vivo. This study examined if soluble factors produced by MSCs in contact with titanium-aluminum-vanadium (Ti6Al4V) implants possessing a complex multiscale biomimetic topography are able to induce osteogenesis ectopically. Ti6Al4V disks were grit-blasted and acid-etched to create surfaces possessing macroscale and microscale roughness (MM), micro/meso/nanoscale topography (MN), and macro/micro/meso/nanoscale topography (MMNTM). Polyether-ether-ketone (PEEK) disks were also fabricated by machining to medical-grade specifications. Surface properties were assessed by scanning electron microscopy, contact angle, optical profilometry, and x-ray photoelectron spectroscopy. MSCs were cultured in growth media (GM). Proteins and local factors in their conditioned media (CM) were measured on days 4, 8, 10 and 14: osteocalcin, osteopontin, osteoprotegerin, BMP2, BMP4, and cytokines interleukins 6, 4 and 10 (IL6, IL4, and IL10). CM was collected from D14 MSCs on MMNTMand tissue culture polystyrene (TCPS) and lyophilized. Gel capsules containing active demineralized bone matrix (DBM), heat-inactivated DBM (iDBM), and iDBM + MMN-GM were implanted bilaterally in the gastrocnemius of athymic nude mice (N= 8 capsules/group). Controls included iDBM + GM; iDBM + TCPS-CM from D5 to D10 MSCs; iDBM + MMN-CM from D5 to D10; and iDBM + rhBMP2 (R&D Systems) at a concentration similar to D5-D10 production of MSCs on MMNTMsurfaces. Legs were harvested at 35D. Bone formation was assessed by micro computed tomography and histomorphometry (hematoxylin and eosin staining) with the histology scored according to ASTM 2529-13. DNA was greatest on PEEK at all time points; DNA was lowest on MN at early time points, but increased with time. Cells on PEEK exhibited small changes in differentiation with reduced production of BMP2. Osteoblast differentiation was greatest on the MN and MMNTM, reflecting increased production of BMP2 and BMP4. Pro-regenerative cytokines IL4 and IL10 were increased on Ti-based surfaces; IL6 was reduced compared to PEEK. None of the media from TCPS cultures was osteoinductive. However, MMN-CM exhibited increased bone formation compared to iDBM and iDBM + rhBMP2. Furthermore, exogenous rhBMP2 alone, at the concentration found in MMN-CM collected from D5 to D10 cultures, failed to induce new bone, indicating that other factors in the CM play a critical role in that osteoinductive microenvironment. MSCs cultured on MMNTMTi6Al4V surfaces differentiate and produce an increase in local factors, including BMP2, and the CM from these cultures can induce ectopic bone formation compared to control groups, indicating that the increased bone formation arises from the local response by MSCs to a biomimetic, multiscale surface topography.
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Affiliation(s)
- Michael B Berger
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA 23284, United States of America
| | - D Joshua Cohen
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA 23284, United States of America
| | - Kyla B Bosh
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA 23284, United States of America
| | - Marina Kapitanov
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA 23284, United States of America
| | - Paul J Slosar
- SpineCare Medical Group, 455 Hickey Blvd., Suite 310, Daly City, CA 94015, United States of America
| | - Michael M Levit
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA 23284, United States of America
| | - Michelle Gallagher
- Medtronic, Applied Research-Spine, Minneapolis, MN, United States of America
| | - Jeremy J Rawlinson
- Medtronic, Applied Research-Spine, Minneapolis, MN, United States of America
| | - Zvi Schwartz
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA 23284, United States of America.,Department of Periodontology, University of Texas Health Science Center at San Antonio, 7703, Floyd Curl Drive, San Antonio, TX 78229, United States of America
| | - Barbara D Boyan
- Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA 23284, United States of America.,Wallace H. Coulter Department of Biomedical Engineering at the Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, GA 30332, United States of America
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Lopez Poncelas M, La Barbera L, Rawlinson JJ, Polly DW, Aubin CE. Influence of spinal lordosis correction location on proximal junctional failure: a biomechanical study. Spine Deform 2023; 11:49-58. [PMID: 36083462 DOI: 10.1007/s43390-022-00571-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 08/13/2022] [Indexed: 10/14/2022]
Abstract
STUDY DESIGN Assessment of sagittal lordosis distribution on mechanical proximal junctional failure-related risks through computer-based biomechanical models. OBJECTIVE To biomechanically assess how lordosis distribution influences radiographical and biomechanical indices related to Proximal Junctional Failure (PJF). The "optimal" patient-specific targets to restore the sagittal balance in posterior spinal fusion are still not known. Among these, the effect of the lumbar lordosis correction strategy on complications such as PJF remain uncertain. METHODS In this computational biomechanical study, five adult spinal deformity patients who underwent posterior spinal fixation were retrospectively reviewed. Their surgery, first erect posture and flexion movement were simulated with a patient-specific multibody model. Three pedicle subtraction osteotomy (PSO) levels (L3, L4, and L5) were simulated, with consistent global lordosis for a given patient and pelvic tilt adjusted accordingly to the actual surgery. Computed loads on the anterior spine and instrumentation were analyzed and compared using Kruskal-Wallis statistical tests and Spearman correlations. RESULTS In these models, no significant correlations were found between the lordosis distribution index (LDI), PSO level and biomechanical PJF-related indices. However, increasing the sagittal vertical axis (SVA) and thoracolumbar junction angle (TLJ) and decreasing the sacral slope (SS) increased the bending moment sustained by the rods at the proximal instrumented level (r = 0.52, 0.57, - 0.56, respectively, p < 0.05). There was a negative correlation between SS and the bending moment held by the adjacent proximal segment (r = - 0.71, p < 0.05). CONCLUSION Based on these biomechanical simulations, there was no correlation between the lordosis distribution and PJF-associated biomechanical factors. However, increasing SS and flattening the TLJ, as postural adjustment strategies required by a more distal PSO, did decrease such PJF-related factors. Sagittal restoration and PJF risks remain multifactorial, and the use of patient-specific biomechanical models may help to better understand the complex interrelated mechanisms.
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Affiliation(s)
- Maeva Lopez Poncelas
- Department of Mechanical Engineering, Polytechnique Montréal, Downtown Station, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada.,Research Center, Sainte-Justine University Hospital Center, 3175, Cote Sainte-Catherine Road, Montreal, QC, H3T 1C5, Canada
| | - Luigi La Barbera
- Department of Mechanical Engineering, Polytechnique Montréal, Downtown Station, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada.,Research Center, Sainte-Justine University Hospital Center, 3175, Cote Sainte-Catherine Road, Montreal, QC, H3T 1C5, Canada.,Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci, 32 20133, Milan, MI, Italy
| | - Jeremy J Rawlinson
- Department of Mechanical Engineering, Polytechnique Montréal, Downtown Station, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada.,Spine Applied Research, Cranial and Spinal Technologies Medtronic, 18400 Pyramid Place, Memphis, TN, 38132, USA
| | - David W Polly
- Department of Orthopaedic Surgery, University of Minnesota, 2512 South 7th Street, Suite R200, Minneapolis, MN, 55455, USA
| | - Carl-Eric Aubin
- Department of Mechanical Engineering, Polytechnique Montréal, Downtown Station, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada. .,Research Center, Sainte-Justine University Hospital Center, 3175, Cote Sainte-Catherine Road, Montreal, QC, H3T 1C5, Canada.
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Lopez Poncelas M, La Barbera L, Rawlinson JJ, Crandall D, Aubin CE. Credibility assessment of patient-specific biomechanical models to investigate proximal junctional failure in clinical cases with adult spine deformity using ASME V&V40 standard. Comput Methods Biomech Biomed Engin 2021; 25:543-553. [PMID: 34427119 DOI: 10.1080/10255842.2021.1968380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Computational models are increasingly used to assess spine biomechanics and support surgical planning. However, varying levels of model verification and validation, along with characterization of uncertainty effects limit the level of confidence in their predictive potential. The objective was to assess the credibility of an adult spine deformity instrumentation model for proximal junction failure (PJF) analysis using the ASME V&V40:2018 framework. To assess model applicability, the surgery, erected posture, and flexion movement of actual clinical cases were simulated. The loads corresponding to PJF indicators for a group of asymptomatic patients and a group of PJF patients were compared. Model consistency was demonstrated by finding PJF indicators significantly higher for the simulated PJF vs. asymptomatic patients. A detailed sensitivity analysis and uncertainty quantification were performed to further establish the model credibility.
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Affiliation(s)
- M Lopez Poncelas
- Department of Mechanical Engineering, Polytechnique Montréal, Montréal, Quebec, Canada.,Research Center, Sainte-Justine University Hospital Center, Montréal, Quebec, Canada
| | - L La Barbera
- Department of Mechanical Engineering, Polytechnique Montréal, Montréal, Quebec, Canada.,Research Center, Sainte-Justine University Hospital Center, Montréal, Quebec, Canada.,Department of Chemistry and Chemical Engineering, Politecnico di Milano, Milano, Italy
| | - J J Rawlinson
- Department of Mechanical Engineering, Polytechnique Montréal, Montréal, Quebec, Canada.,Applied Research, Medtronic Spine, Memphis, TN, USA
| | - D Crandall
- Sonoran Spine Center, Tempe, AZ, USA.,Mayo Clinic School of Medicine, Phoenix, AZ, USA.,School of Medicine, University of Arizona, Phoenix, AZ, USA
| | - C E Aubin
- Department of Mechanical Engineering, Polytechnique Montréal, Montréal, Quebec, Canada.,Research Center, Sainte-Justine University Hospital Center, Montréal, Quebec, Canada
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Kenny M, Cercone M, Rawlinson JJ, Ducharme NG, Bookbinder L, Thompson M, Cheetham J. Transoesophageal ultrasound and computer tomographic assessment of the equine cricoarytenoid dorsalis muscle: Relationship between muscle geometry and exercising laryngeal function. Equine Vet J 2016; 49:395-400. [PMID: 26709115 DOI: 10.1111/evj.12561] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 12/13/2015] [Indexed: 11/27/2022]
Abstract
REASONS FOR PERFORMING STUDY Early detection of recurrent laryngeal neuropathy (RLN) is of considerable interest to the equine industry. OBJECTIVES To describe two imaging modalities, transoesophageal ultrasound (TEU) and computed tomography (CT) with multiplanar reconstruction to assess laryngeal muscle geometry, and determine the relationship between cricoarytenoid dorsalis (CAD) geometry and function. STUDY DESIGN Two-phase study evaluating CAD geometry in experimental horses and horses with naturally occurring RLN. METHODS Equine CAD muscle volume was determined from CT scan sets using volumetric reconstruction with LiveWire. The midbody and caudal dorsal-ventral thickness of the CAD muscle was determined using a TEU in the same horses; and in horses with a range of severity of RLN (n = 112). RESULTS Transoesophageal ultrasound was able to readily image the CAD muscles and lower left:right CAD thickness ratios were observed with increasing disease severity. Computed tomography based muscle volume correlated very closely with ex vivo muscle volume (R2 = 0.77). CONCLUSIONS Computed tomography reconstruction can accurately determine intrinsic laryngeal muscle geometry. A relationship between TEU measurements of CAD geometry and laryngeal function was established. These imaging techniques could be used to track the response of the CAD muscle to restorative surgical treatments such as nerve muscle pedicle graft, nerve anastomosis and functional electrical stimulation.
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Affiliation(s)
- M Kenny
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - M Cercone
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | | | - N G Ducharme
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - L Bookbinder
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - M Thompson
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
| | - J Cheetham
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA
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Brown BN, Siebenlist NJ, Cheetham J, Ducharme NG, Rawlinson JJ, Bonassar LJ. Computed tomography-guided tissue engineering of upper airway cartilage. Tissue Eng Part C Methods 2013; 20:506-13. [PMID: 24164398 DOI: 10.1089/ten.tec.2013.0216] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Normal laryngeal function has a large impact on quality of life, and dysfunction can be life threatening. In general, airway obstructions arise from a reduction in neuromuscular function or a decrease in mechanical stiffness of the structures of the upper airway. These reductions decrease the ability of the airway to resist inspiratory or expiratory pressures, causing laryngeal collapse. We propose to restore airway patency through methods that replace damaged tissue and improve the stiffness of airway structures. A number of recent studies have utilized image-guided approaches to create cell-seeded constructs that reproduce the shape and size of the tissue of interest with high geometric fidelity. The objective of the present study was to establish a tissue engineering approach to the creation of viable constructs that approximate the shape and size of equine airway structures, in particular the epiglottis. Computed tomography images were used to create three-dimensional computer models of the cartilaginous structures of the larynx. Anatomically shaped injection molds were created from the three-dimensional models and were seeded with bovine auricular chondrocytes that were suspended within alginate before static culture. Constructs were then cultured for approximately 4 weeks post-seeding and evaluated for biochemical content, biomechanical properties, and histologic architecture. Results showed that the three-dimensional molded constructs had the approximate size and shape of the equine epiglottis and that it is possible to seed such constructs while maintaining 75%+ cell viability. Extracellular matrix content was observed to increase with time in culture and was accompanied by an increase in the mechanical stiffness of the construct. If successful, such an approach may represent a significant improvement on the currently available treatments for damaged airway cartilage and may provide clinical options for replacement of damaged tissue during treatment of obstructive airway disease.
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Affiliation(s)
- Bryan N Brown
- 1 Department of Biomedical Engineering, College of Engineering, Cornell University , Ithaca, New York
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Abstract
REASONS FOR PERFORMING THE STUDY Upper airway obstruction is a common problem in the performance horse as the soft tissues of the larynx collapse into the airway, yet there is a paucity of information on biomechanical properties for the structural cartilage components. OBJECTIVE To measure the geometry and compressive mechanical properties of the hyaline cartilage to improve understanding of laryngeal function and morphology. METHODS A total of 11 larynges were harvested from Thoroughbred and Standardbred racehorses. During gross dissection, linear dimensions of the cricoid were obtained. From both the cricoid and arytenoid, specimens were cored to obtain 6 mm disc samples from 3 sites within the dorsal cricoid (caudal, middle and rostral) and 2 central sites in the arytenoids (inner, outer). The specimens were mechanically tested using radial confined compression to calculate the aggregate modulus and permeability of the tissue. The biomechanical data were analysed using a nested mixed effects model. RESULTS Geometrically, the cricoid has relatively straight walls compared to the morphology of human, ovine and canine larynges. There were significant observations of higher modulus with increasing age (0.13 MPa per year; P = 0.007) and stiffer cricoid cartilage (2.29 MPa) than the arytenoid cartilage (0.42 MPa; P<0.001), but no difference was observed between the left and right sides. Linear contrasts showed that the rostral aspect (2.51 MPa) of the cricoid was 20% stiffer than the caudal aspect (2.09 MPa; P = 0.025), with no difference between the arytenoid sites. CONCLUSIONS The equine larynx is a well supported structure due to both the geometry and material properties of the cricoid cartilage. The hyaline structure is an order of magnitude higher in compressive modulus compared to the arytenoids and other hyaline-composed tissues. POTENTIAL RELEVANCE These characterisations are important to understand the biomechanics of laryngeal function and the mechanisms involved with surgical interventions.
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Witte TH, Cheetham J, Rawlinson JJ, Soderholm LV, Ducharme NG. A transducer for measuring force on surgical sutures. Can J Vet Res 2010; 74:299-304. [PMID: 21197230 PMCID: PMC2949343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 12/02/2009] [Indexed: 05/30/2023]
Abstract
The objective of this study was to validate, both in vitro and in an ex vivo model, a technique for the measurement of forces exerted on surgical sutures. For this purpose, a stainless steel E-type buckle force transducer was designed and constructed. A strain gauge was mounted on the central beam of the transducer to measure transducer deformation. The transducer was tested and calibrated on a single strand of surgical suture during cyclic loading. Further validation was performed using a previously published cadaveric model of laryngoplasty in the horse. Linear regression of transducer output with actual force during calibration tests resulted in mean R² values of 1.00, 0.99, and 0.99 for rising slope, falling slope, and overall slope, respectively. The R² was not less than 0.96 across an average of 75 cycles per test. The difference between rising slope and falling slope was 4%. Over 45 846 samples, the predicted force from transducer output showed a mean error of 4%. In vitro validation produced an adjusted R² of 0.99 when the force on the suture was regressed against translaryngeal pressure in a mixed-effects model. E-type buckle force transducers showed a highly linear output over a physiological force range when applied to surgical suture in vitro and in an ex vivo model of laryngoplasty. With appropriate calibration and short-term in vivo implantation, these transducers may advance our knowledge of the mechanisms of success and failure of techniques, such as laryngoplasty, that use structural suture implants.
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Affiliation(s)
- Thomas H Witte
- Equine Performance Testing Clinic, Department of Veterinary Clinical Sciences, Cornell University Hospital for Animals, Cornell University College of Veterinary Medicine, Ithaca, New York 14850, USA.
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Abstract
Tuning and calibration are processes for improving the representativeness of a computer simulation code to a physical phenomenon. This article introduces a statistical methodology for simultaneously determining tuning and calibration parameters in settings where data are available from a computer code and the associated physical experiment. Tuning parameters are set by minimizing a discrepancy measure while the distribution of the calibration parameters are determined based on a hierarchical Bayesian model. The proposed Bayesian model views the output as a realization of a Gaussian stochastic process with hyperpriors. Draws from the resulting posterior distribution are obtained by the Markov chain Monte Carlo simulation. Our methodology is compared with an alternative approach in examples and is illustrated in a biomechanical engineering application. Supplemental materials, including the software and a user manual, are available online and can be requested from the first author.
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Affiliation(s)
- Gang Han
- H. Lee Moffitt Cancer Center & Research Institute, MRC/BIOSTAT, 12902 Magnolia Drive, Tampa, FL 33612, ( )
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Abstract
OBJECTIVE To report management of a chronic slipped capital femoral epiphysis (SCFE) in an alpaca using cementless total hip replacement (THR). STUDY DESIGN Case report. ANIMAL An 18-month-old, 47 kg alpaca male. METHODS Cementless THR was performed in an alpaca with a chronic, right SCFE, and secondary osteoarthritis. Force plate gait analysis was performed before and 8 weeks after surgery. Outcome was determined through clinical evaluation, radiography, and force plate gait analysis. RESULTS Cementless THR resulted in marked improvement in the alpaca's comfort level, degree of lameness, and range of motion. On preoperative force plate gait analysis there was decreased contact time (P=.01) and vertical impulse (P<.01) of the affected limb, whereas at 8 weeks postoperatively significant differences in gait analysis between pelvic limbs were not apparent. CONCLUSION THR using a BioMedtrix canine cementless modular prosthesis restored hip function in an alpaca with coxofemoral osteoarthritis from chronic SCFE. CLINICAL RELEVANCE THR may be an appropriate treatment for selected traumatic and degenerative conditions of the coxofemoral joint in alpacas.
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Affiliation(s)
- Kyla F Ortved
- Cornell University Hospital for Animals and Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
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Rawlinson JJ, Closkey RF, Davis N, Wright TM, Windsor R. Stemmed implants improve stability in augmented constrained condylar knees. Clin Orthop Relat Res 2008; 466:2639-43. [PMID: 18709431 PMCID: PMC2565014 DOI: 10.1007/s11999-008-0424-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2007] [Accepted: 07/11/2008] [Indexed: 01/31/2023]
Abstract
We previously combined experimental and computational measures to ascertain whether tibial stem augmentation reduces bone strains beneath constrained condylar implants. Using these same integrated approaches, we examined the benefit of a stem when a wedge is used. Implants were removed from the eight paired cadaver specimens from our previous experiment, and oblique defects created that were restored with 15 degrees metallic wedges cemented in place. We applied a varus moment and an axial load and monitored relative motion between implant and bone. Specimen-specific 3-D finite element models were constructed from CT scans and radiographs to examine bone stress in the proximal tibia. Implants with a wedge but no stem had greater motion than the previous control with no stem or wedge. Use of a modular stem with a wedge maintained the same level of motion as the primary case, suggesting that a stem is preferable when a wedge is utilized. The computational models confirmed this conclusion with a 30% reduction in bone stress compared to 17% in the primary case without a wedge. The wedge carried more axial load compared to the primary implant due to its support on stiff metaphyseal bone.
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Affiliation(s)
| | - Robert F. Closkey
- Ocean Orthopedic Associates, 530 Lakehurst Road, Tom’s River, NJ 08755 USA
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Ballyns JJ, Gleghorn JP, Niebrzydowski V, Rawlinson JJ, Potter HG, Maher SA, Wright TM, Bonassar LJ. Image-guided tissue engineering of anatomically shaped implants via MRI and micro-CT using injection molding. Tissue Eng Part A 2008; 14:1195-202. [PMID: 18593357 DOI: 10.1089/ten.tea.2007.0186] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study demonstrates for the first time the development of engineered tissues based on anatomic geometries derived from widely used medical imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). Computer-aided design and tissue injection molding techniques have demonstrated the ability to generate living implants of complex geometry. Due to its complex geometry, the meniscus of the knee was used as an example of this technique's capabilities. MRI and microcomputed tomography (microCT) were used to design custom-printed molds that enabled the generation of anatomically shaped constructs that retained shape throughout 8 weeks of culture. Engineered constructs showed progressive tissue formation indicated by increases in extracellular matrix content and mechanical properties. The paradigm of interfacing tissue injection molding technology can be applied to other medical imaging techniques that render 3D models of anatomy, demonstrating the potential to apply the current technique to engineering of many tissues and organs.
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Affiliation(s)
- Jeffery J Ballyns
- Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, USA
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Rawlinson JJ, Punga KP, Gunsallus KL, Bartel DL, Wright TM. Wear simulation of the ProDisc-L disc replacement using adaptive finite element analysis. J Neurosurg Spine 2007; 7:165-73. [PMID: 17688056 DOI: 10.3171/spi-07/08/166] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT An understanding of the wear potential of total disc replacements (TDRs) is critical as these new devices are increasingly introduced into clinical practice. The authors analyzed the wear potential of a ProDisc-L implant using an adaptive finite element (FE) technique in a computational simulation representing a physical wear test. METHODS The framework for calculating abrasive wear, first validated using a model of a total hip replacement (THR), was then used to model the ProDisc-L polyethylene component that is fixed to the inferior endplate and articulates with the rigid superior endplate. Proposed standards for spine wear testing protocols specified the inputs of flexion-extension (6/-3 degrees), lateral bending (+/- 2 degrees), axial twist (+/- 1.5 degrees), and axial load (200-1750 N or 600-2000 N) applied to the model through 10 million simulation cycles. The model was calibrated with a wear coefficient determined from an experimental wear test. Implicit FE analyses were then performed for variations in coefficient of friction, polyethylene elastic modulus, radial clearance, and polyethylene component thickness to investigate their effects on wear. RESULTS Using the initial loading protocol (single-peaked axial load profile of 300-1750 N) from the experimental wear test, the polyethylene wear rate was 9.82 mg per million cycles. When a double-peaked loading profile (600-2000 N) was applied, the wear rate increased to 11.77 mg per million cycles. Parametric design variations produced only small changes in wear rates for this simulation. CONCLUSIONS The chosen design variables had little effect on the resultant wear rates. The comparable wear rate for the THR validation analysis was 16.17 mg per million cycles, indicating that, using this framework, the wear potential of the TDR was equivalent to, if not better, than the THR using joint-specific loading standards.
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Affiliation(s)
- Jeremy J Rawlinson
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
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Abstract
Wear mechanisms in polyethylene components for total knee replacements are inherently mechanical; the local stresses or strains exceed some material limit. Retrieval analysis and knee simulators have provided the means to quantify the damage observed in vivo or in vitro. These results have been circumstantially linked to the material stresses obtained from computational simulations using finite element analysis, knee simulator tests, and computational simulations of two condylar knee designs. We hypothesize that if an equivalent loading environment is produced in the computational simulation, we can correlate the distribution of computed stresses with observed damage of simulator specimens and further relate design differences to in vivo performance from retrieval analyses. The finite element model agreed with the knee simulator kinematics and kinetics within 2-13%, and composite FEA contact areas matched 66-90% of the damage areas due to burnishing on the simulator specimens. Burnishing was the primary mode of damage for both the simulator and retrieval specimens corresponding with the relatively low magnitudes of contact stress observed. Both the computational and experimental techniques underpredicted the amount determined from retrieval analysis, but the differences between the two designs were consistent for all three methods. Combining these techniques strengthens the applicability of the computational simulation while highlighting the complementary approach of these methods for preclinical testing and assessing the link between material state and damage.
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Affiliation(s)
- Jeremy J Rawlinson
- Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, USA.
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Rawlinson JJ, Peters LE, Campbell DA, Windsor R, Wright TM, Bartel DL. Cancellous bone strains indicate efficacy of stem augmentation in constrained condylar knees. Clin Orthop Relat Res 2005; 440:107-16. [PMID: 16239792 DOI: 10.1097/01.blo.0000187340.10003.68] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Modular augmented stems of a constrained condylar knee implant are intended to improve tibial fixation under increased varus/valgus loads, but conflicting studies have not yet indicated the factors determining stem usage and performance. To address this, we combined a paired-tibiae, cadaveric experiment of unstemmed and stemmed tibial components with specimen-specific computational models. We hypothesized that the stem would improve implant stability by decreasing implant motion and compressive strains in the proximal cancellous bone due to load transfer by the stem. The models also would indicate the important factors governing stem performance. Large variations of the displacements arose because of loading and biologic variability indicating the inconclusive effects of a stem. Despite these variations, the models showed that a stem augment consistently decreased the strains (30%-50%) in the bone beneath the tray. In tibiae of sufficient stiffness, the supporting cancellous bone did not approach yield, suggesting that a stem augment may not always be necessary. On the other hand, tibial specimens with reduced bone quality and lower stiffness benefited from a stem augment that transferred load to the distal cortical bone. Therefore, patient selection and proper sizing of the implant were identified as important factors in the analyses.
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Abstract
The potential for wear in UHMWPE components for total knee replacements can be reduced by decreasing the stresses and strains arising from tibial-femoral contact. The conformity of the articular surfaces has a large effect on the resultant stresses, and components that achieve flat medial-lateral contact have been assumed to produce the lowest stresses due to their perfect conformity. We computed the stresses arising from curved and flat contact on a half-space using two-dimensional, plane strain elasticity solutions and finite element analyses to compare the performance of curved and flat indenters. These indenters were represented by a polynomial so the profiles could be continuously varied from curved to flat. Curved contact resulted in maximum stresses at the center of contact, while flat contact produced maximum stresses at the edge of contact. In addition, three contemporary tibial configurations (flat-on-flat, curved-on-flat, and curved-on-curved geometries) were analyzed using the finite element method with nonlinear material properties. The maximum contact stress, von Mises stress, and von Mises strain were lowest for the curved-on-curved model. The other configurations resulted in higher contact stresses, von Mises stresses, and von Mises strains. The perfect conformity arising from flat contact did not reduce the contact stresses in the UHMWPE component. The tensile stresses, however, were lowest for the flat-on-flat geometry compared with the other two configurations. Relating these distinct differences could prove useful in interpretation of data from simulator and retrieval studies.
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Affiliation(s)
- Jeremy J Rawlinson
- Cornell-Hospital for Special Surgery Program in Biomechanical Engineering, Cornell University, Ithaca, NY, USA.
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Bartel DL, Rawlinson JJ, Burstein AH, Ranawat CS, Flynn WF. Stresses in polyethylene components of contemporary total knee replacements. Clin Orthop Relat Res 1995:76-82. [PMID: 7671500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Contemporary knee designs differ considerably in the conformity that exists between the articulating surfaces of the femoral and tibial components. The thickness of the polyethylene components also varies from design to design. Conformity and thickness affect the stresses associated with surface damage and the subsequent generation of harmful polyethylene debris. In this study, the stresses and strains caused by contact were calculated for 8 contemporary knee prostheses. Finite element analysis using large-strain theory was used to determine the stresses and strains for the minimum available polyethylene thickness and for the knee in flexion. The greatest differences among designs was for the von Mises strain, which reached its maximum beneath the surface. The differences in stresses were less notable because of the nonlinear material behavior of the polyethylene. This study also confirmed the advantages of designs that have more conforming articulating surfaces and thicker polyethylene components.
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Affiliation(s)
- D L Bartel
- Cornell University, Ithaca, NY 14853, USA
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