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Farhart P, Beakley D, Diwan A, Duffield R, Rodriguez EP, Chamoli U, Watsford M. Intrinsic variables associated with low back pain and lumbar spine injury in fast bowlers in cricket: a systematic review. BMC Sports Sci Med Rehabil 2023; 15:114. [PMID: 37730648 PMCID: PMC10512628 DOI: 10.1186/s13102-023-00732-1] [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: 02/24/2023] [Accepted: 09/12/2023] [Indexed: 09/22/2023]
Abstract
BACKGROUND Lumbar spine injuries in fast bowlers account for the greatest missed playing time in cricket. A range of extrinsic and intrinsic variables are hypothesised to be associated with low back pain and lumbar spine injury in fast bowlers, and an improved understanding of intrinsic variables is necessary as these may alter load tolerance and injury risk associated with fast bowling. This review critically evaluated studies reporting intrinsic variables associated with low back pain and lumbar spine injury in fast bowlers and identified areas for future investigation. METHODS OVID Medline, EMBASE, SPORTDiscus, CINAHL, Web of Science and SCOPUS databases were last searched on 3 June 2022 to identify studies investigating intrinsic variables associated with low back pain and lumbar spine injury in cricket fast bowlers. Terms relevant to cricket fast bowling, and intrinsic variables associated with lumbar spine injury and low back pain in fast bowlers were searched. 1,503 abstracts were screened, and 118 full-text articles were appraised to determine whether they met inclusion criteria. Two authors independently screened search results and assessed risk of bias using a modified version of the Quality in Prognostic Studies tool. RESULTS Twenty-five studies met the inclusion criteria. Overall, no included studies demonstrated a low risk of bias, two studies were identified as moderate risk, and twenty-three studies were identified as high risk. Conflicting results were reported amongst studies investigating associations of fast bowling kinematics and kinetics, trunk and lumbar anatomical features, anthropometric traits, age, and neuromuscular characteristics with low back pain and lumbar spine injury. CONCLUSION Inconsistencies in results may be related to differences in study design, injury definitions, participant characteristics, measurement parameters, and statistical analyses. Low back pain and lumbar spine injury occurrence in fast bowlers remain high, and this may be due to an absence of low bias studies that have informed recommendations for their prevention. Future research should employ clearly defined injury outcomes, analyse continuous datasets, utilise models that better represent lumbar kinematics and kinetics during fast bowling, and better quantify previous injury, lumbar anatomical features and lumbar maturation. TRIAL REGISTRATION Open Science Framework https://doi.org/10.17605/OSF.IO/ERKZ2 .
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Affiliation(s)
- Patrick Farhart
- School of Sport, Exercise and Rehabilitation, Faculty of Health, Human Performance Research Centre, Moore Park Precinct, University of Technology Sydney, Broadway, NSW, 2007, Australia.
- Spine Labs, Discipline of Surgery, St. George and Sutherland Campus of the Clinical School, Faculty of Medicine, University of New South Wales, Kogarah, NSW, 2217, Australia.
- Cricket New South Wales, 161 Silverwater Road, Sydney Olympic Park, Sydney, NSW, 2127, Australia.
- Delhi Capitals, JSW GMR Cricket Private Limited, Bahadurshah Zafar Marg, New Delhi, 110002, India.
| | - David Beakley
- Deakin University, Burwood Highway, Burwood, VIC, 3125, Australia
| | - Ashish Diwan
- Spine Labs, Discipline of Surgery, St. George and Sutherland Campus of the Clinical School, Faculty of Medicine, University of New South Wales, Kogarah, NSW, 2217, Australia
- Spine Service, Department of Orthopaedic Surgery, St. George Hospital Campus, Kogarah, NSW, 2217, Australia
| | - Rob Duffield
- School of Sport, Exercise and Rehabilitation, Faculty of Health, Human Performance Research Centre, Moore Park Precinct, University of Technology Sydney, Broadway, NSW, 2007, Australia
| | - Elizabeth Pickering Rodriguez
- School of Sport, Exercise and Rehabilitation, Faculty of Health, Human Performance Research Centre, Moore Park Precinct, University of Technology Sydney, Broadway, NSW, 2007, Australia
| | - Uphar Chamoli
- Spine Labs, Discipline of Surgery, St. George and Sutherland Campus of the Clinical School, Faculty of Medicine, University of New South Wales, Kogarah, NSW, 2217, Australia
- School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Broadway, NSW, 2007, Australia
| | - Mark Watsford
- School of Sport, Exercise and Rehabilitation, Faculty of Health, Human Performance Research Centre, Moore Park Precinct, University of Technology Sydney, Broadway, NSW, 2007, Australia
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Ramakrishna VA, Chamoli U, Larosa AG, Mukhopadhyay SC, Gangadhara Prusty B, Diwan AD. A biomechanical comparison of posterior fixation approaches in lumbar fusion using computed tomography based lumbosacral spine modelling. Proc Inst Mech Eng H 2023; 237:243-253. [PMID: 36651492 DOI: 10.1177/09544119221149119] [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] [Indexed: 01/19/2023]
Abstract
Extreme lateral interbody fusion (XLIF) may be performed with a standalone interbody cage, or with the addition of unilateral or bilateral pedicle screws; however, decisions regarding supplemental fixation are predominantly based on clinical indicators. This study examines the impact of posterior supplemental fixation on facet micromotions, cage loads and load-patterns at adjacent levels in a L4-L5 XLIF at early and late fusion stages. CT data from an asymptomatic subject were segmented into anatomical regions and digitally stitched into a surface mesh of the lumbosacral spine (L1-S1). The interbody cage and posterior instrumentation (unilateral and bilateral) were inserted at L4-L5. The volumetric mesh was imported into finite element software for pre-processing, running nonlinear static solves and post-processing. Loads and micromotions at the index-level facets reduced commensurately with the extent of posterior fixation accompanying the XLIF, while load-pattern changes observed at adjacent facets may be anatomically dependent. In flexion at partial fusion, compressive stress on the cage reduced by 54% and 72% in unilateral and bilateral models respectively; in extension the reductions were 58% and 75% compared to standalone XLIF. A similar pattern was observed at full fusion. Unilateral fixation provided similar stability compared to bilateral, however there was a reduction in cage stress-risers with the bilateral instrumentation. No changes were found at adjacent discs. Posterior supplemental fixation alters biomechanics at the index and adjacent levels in a manner that warrants consideration alongside clinical information. Unilateral instrumentation is a more efficient option where the stability requirements and subsidence risk are not excessive.
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Affiliation(s)
- Vivek As Ramakrishna
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Kensington, NSW, Australia.,Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia.,School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, Australia
| | - Uphar Chamoli
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia.,School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, NSW, Australia
| | - Alessandro G Larosa
- School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, NSW, Australia
| | - Subhas C Mukhopadhyay
- School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, Australia
| | - B Gangadhara Prusty
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Kensington, NSW, Australia
| | - Ashish D Diwan
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia.,Spine Service, Department of Orthopaedic Surgery, St. George Hospital Campus, Kogarah, NSW, Australia
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Ramakrishna VAS, Chamoli U, Mukhopadhyay SC, Diwan AD, Prusty BG. Measuring compressive loads on a 'smart' lumbar interbody fusion cage: Proof of concept. J Biomech 2023; 147:111440. [PMID: 36640615 DOI: 10.1016/j.jbiomech.2023.111440] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/08/2022] [Accepted: 01/06/2023] [Indexed: 01/11/2023]
Abstract
There are several complications associated with lumbar interbody fusion surgery however, pseudarthrosis (non-union) presents a multifaceted challenge in the postoperative management of the patient. Rates of pseudarthrosis range from 3 to 20 % in patients with healthy bone and 20 to 30 % in patients with osteoporosis. The current methods in post-operative follow-up - radiographs and CT, have high false positive rates and poor agreement between them. The aim of this study was to develop and test a proof-of-concept load-sensing interbody cage that may be used to monitor fusion progression. Piezoresistive pressure sensors were calibrated and embedded within a polyether ether ketone (PEEK) interbody cage. Silicone and poly (methyl methacrylate) (PMMA) were inserted in the graft regions to simulate early and solid fusion. The load-sensing cage was subjected to distributed and eccentric compressive loads up to 900 N between synthetic lumbar vertebral bodies. Under maximum load, the anterior sensors recorded a 56-58 % reduction in pressure in the full fusion state compared to early fusion. Lateral regions measured a 36-37 % stress reduction while the central location reduced by 45 %. The two graft states were distinguishable by sensor-recorded pressure at lower loads. The sensors more effectively detected left and right eccentric loads compared to anterior and posterior. Further, the load-sensing cage was able to detect changes in endplate stiffness. The proof-of-concept 'smart' cage could detect differences in fusion state, endplate stiffness, and loading conditions in this in vitro experimental setup.
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Affiliation(s)
- Vivek A S Ramakrishna
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Kensington, New South Wales, Australia; Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, New South Wales, Australia; School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia.
| | - Uphar Chamoli
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, New South Wales, Australia; School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Subhas C Mukhopadhyay
- School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Ashish D Diwan
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, New South Wales, Australia; Spine Service, Department of Orthopaedic Surgery St. George Hospital Campus, Kogarah, New South Wales, Australia
| | - B Gangadhara Prusty
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Kensington, New South Wales, Australia
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Ramakrishna VAS, Chamoli U, Larosa AG, Mukhopadhyay SC, Prusty BG, Diwan AD. Finite element modeling of temporal bone graft changes in XLIF: Quantifying biomechanical effects at adjacent levels. J Orthop Res 2022; 40:1420-1435. [PMID: 34432322 DOI: 10.1002/jor.25166] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [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: 03/10/2021] [Revised: 06/08/2021] [Accepted: 08/16/2021] [Indexed: 02/04/2023]
Abstract
Extreme lateral interbody fusion allows for the insertion of a large-footprint interbody cage while maintaining the presence of natural stabilizing ligaments and the facets. It is unclear how the load-distribution mechanisms through these structures alter with temporal changes in the bone graft. The aim of this study was to examine the effects of temporal bone graft changes on load distribution among the cage, graft, and surrounding spinal structures using finite element analysis. Thoracolumbosacral spine computed tomography data from an asymptomatic male subject were segmented into anatomical regions of interest and digitally stitched to generate a surface mesh of the lumbar spine (L1-S1). The interbody cage was inserted into the L4-L5 region during surface meshing. A volumetric mesh was generated and imported into finite element software for pre-processing, running nonlinear static solves, and post-processing. Temporal stiffening was simulated in the graft region with unbonded (Soft Callus, Temporal Stages 1-3, Solid Graft) and bonded (Partial Fusion, Full Fusion) contact. In flexion and extension, cage stress reduced by 20% from the soft callus to solid graft state. Force on the graft was directly related to its stiffness, and load-share between the cage and graft improved with increasing graft stiffness, regardless of whether contact was fused with the endplates. Fused contact between the cage-graft complex and the adjacent endplates shifted load-distribution pathways from the ligaments and facets to the implant, however, these changes did not extend to adjacent levels. These results suggest that once complete fusion is achieved, the existing load paths are seemingly diminished.
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Affiliation(s)
- Vivek A S Ramakrishna
- School of Mechanical and Manufacturing Engineering, Faculty of Engineering, University of New South Wales, Sydney, Kensington, New South Wales, Australia.,Spine Labs, St. George & Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia.,School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Uphar Chamoli
- Spine Labs, St. George & Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia.,School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Alessandro G Larosa
- School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Subhas C Mukhopadhyay
- School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - B Gangadhara Prusty
- School of Mechanical and Manufacturing Engineering, Faculty of Engineering, University of New South Wales, Sydney, Kensington, New South Wales, Australia
| | - Ashish D Diwan
- Spine Labs, St. George & Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia.,Department of Orthopaedic Surgery, Spine Service, St. George Hospital Campus, Kogarah, New South Wales, Australia
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Chepurin D, Chamoli U, Diwan AD. Bony Stress and Its Association With Intervertebral Disc Degeneration in the Lumbar Spine: A Systematic Review of Clinical and Basic Science Studies. Global Spine J 2022; 12:964-979. [PMID: 34018442 PMCID: PMC9344512 DOI: 10.1177/21925682211008837] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
STUDY DESIGN Translational review encompassing basic science and clinical evidence. OBJECTIVES Multiple components of the lumbar spine interact during its normal and pathological function. Bony stress in the lumbar spine is recognized as a factor in the development of pars interarticularis defect and stress fractures, but its relationship with intervertebral disc (IVD) degeneration is not well understood. Therefore, we conducted a systematic review to examine the relationship between bony stress and IVD degeneration. METHODS Online databases Scopus, PubMed and MEDLINE via OVID were searched for relevant studies published between January 1980-February 2020, using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. Two authors independently analyzed the data, noting characteristics and biases in various studies. RESULTS Thirty-two articles were included in the review: 8 clinical studies, 9 finite element modeling studies, 3 in-vivo biomechanical testing studies, and 12 in-vitro biomechanical testing studies. Of the 32 articles, 19 supported, 4 rejected and 9 made no conclusion on the hypothesis that there is a positive associative relationship between IVD degeneration and bony stress. However, sufficient evidence was not available to confirm or reject a causal relationship. CONCLUSIONS Most studies suggest that the prevalence of IVD degeneration increases in the presence of bony stress; whether a causal relationship exists is unclear. The literature recommends early diagnosis and clinical suspicion of IVD degeneration and bony stress. Longitudinal studies are required to explore causal relationships between IVD degeneration and bony stress.
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Affiliation(s)
- Daniel Chepurin
- Department of Orthopaedic Surgery,
Spine Service, St. George & Sutherland Clinical School, University of New South
Wales Australia, Kogarah, Sydney, New South Wales, Australia,Department of Medicine, Faculty of Medicine Nursing & Health
Sciences, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Uphar Chamoli
- Department of Orthopaedic Surgery,
Spine Service, St. George & Sutherland Clinical School, University of New South
Wales Australia, Kogarah, Sydney, New South Wales, Australia,School of Biomedical Engineering,
Faculty of Engineering & Information Technology, University of Technology
Sydney, Ultimo, Sydney, New South Wales, Australia,Uphar Chamoli, Spine Service, L5, Suite 16,
St. George Private Hospital, Kogarah, NSW 2217, Australia.
| | - Ashish D. Diwan
- Department of Orthopaedic Surgery,
Spine Service, St. George & Sutherland Clinical School, University of New South
Wales Australia, Kogarah, Sydney, New South Wales, Australia
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Mah D, Chamoli U, Smith GCS. Usefulness of computed tomography based three-dimensional reconstructions to assess the critical shoulder angle. World J Orthop 2021; 12:301-309. [PMID: 34055587 PMCID: PMC8152441 DOI: 10.5312/wjo.v12.i5.301] [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] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 01/28/2021] [Accepted: 03/08/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The critical shoulder angle (CSA) is a radiographic measurement that provides an assessment of both glenoid inclination and acromial length. Higher values may correlate with the presence of rotator cuff tears. However, it is difficult to obtain a high-quality true anteroposterior (AP) radiograph of the shoulder, with any excess scapular version or flexion/extension resulting in deviation from the true CSA value. Three-dimensional (3D) bony reconstructions of computed tomography (CT) shoulder scans may be able to be rotated to obtain a similar view to that of true AP radiographs.
AIM To compare CSA measurements performed on 3D bony CT reconstructions, with those on corresponding true AP radiographs.
METHODS CT shoulder scans were matched with true AP radiographs that were classified as either Suter-Henninger type A or C quality. 3D bony reconstructions were segmented from the CT scans, and rotated to replicate an ideal true AP view. Two observers performed CSA measurements using both CT and radiographic images. Measurements were repeated after a one week interval. Reliability was assessed using intraclass correlation coefficients (ICCs) and Bland-Altman plots [bias, limits of agreement (LOA)].
RESULTS Twenty CT shoulder scans were matched. The mean CSA values were 32.55° (± 4.26°) with radiographs and 29.82° (± 3.49°) with the CT-based method [mean difference 2.73° (± 2.86°); P < 0.001; bias +2.73°; LOA -2.17° to +7.63°]. There was a strong correlation between the two methods (r = 0.748; P < 0.001). Intra-observer reliability was similar, but the best intra-observer values were achieved by the most experienced observer using the CT-based method [ICC: 0.983 (0.958-0.993); bias +0.03°, LOA -1.28° to +1.34°]. Inter-observer reliability was better with the CT-based method [ICC: 0.897 (0.758-0.958), bias +0.24°, LOA -2.93° to +3.41°].
CONCLUSION The described CT-based method may be a suitable alternative for critical shoulder angle measurement, as it overcomes the difficulty in obtaining a true AP radiographic view.
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Affiliation(s)
- Dominic Mah
- Faculty of Medicine, University of New South Wales, Sydney 2052, New South Wales, Australia
| | - Uphar Chamoli
- Spine Service Research Group, St. George and Sutherland Clinical School, University of New South Wales, Sydney 2052, New South Wales, Australia
- School of Biomedical Engineering, University of Technology Sydney, Sydney 2007, New South Wales, Australia
| | - Geoffrey CS Smith
- St. George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney 2217, New South Wales, Australia
- Department of Orthopaedics, St. George Hospital, Sydney 2217, New South Wales, Australia
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Lyu J, Ling SH, Banerjee S, Zheng JY, Lai KL, Yang D, Zheng YP, Bi X, Su S, Chamoli U. Ultrasound volume projection image quality selection by ranking from convolutional RankNet. Comput Med Imaging Graph 2021; 89:101847. [PMID: 33476927 DOI: 10.1016/j.compmedimag.2020.101847] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 11/15/2020] [Accepted: 12/11/2020] [Indexed: 01/16/2023]
Abstract
Periodic inspection and assessment are important for scoliosis patients. 3D ultrasound imaging has become an important means of scoliosis assessment as it is a real-time, cost-effective and radiation-free imaging technique. With the generation of a 3D ultrasound volume projection spine image using our Scolioscan system, a series of 2D coronal ultrasound images are produced at different depths with different qualities. Selecting a high quality image from these 2D images is the crucial task for further scoliosis measurement. However, adjacent images are similar and difficult to distinguish. To learn the nuances between these images, we propose selecting the best image automatically, based on their quality rankings. Here, the ranking algorithm we use is a pairwise learning-to-ranking network, RankNet. Then, to extract more efficient features of input images and to improve the discriminative ability of the model, we adopt the convolutional neural network as the backbone due to its high power of image exploration. Finally, by inputting the images in pairs into the proposed convolutional RankNet, we can select the best images from each case based on the output ranking orders. The experimental result shows that convolutional RankNet achieves better than 95.5% top-3 accuracy, and we prove that this performance is beyond the experience of a human expert.
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Affiliation(s)
- Juan Lyu
- College of Information and Communication Engineering, Harbin Engineering University, Harbin, China
| | - Sai Ho Ling
- School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - S Banerjee
- School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - J Y Zheng
- Department of Computer Science, Imperial College London, UK
| | - K L Lai
- Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hum, Hong Kong
| | - D Yang
- Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hum, Hong Kong
| | - Y P Zheng
- Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hum, Hong Kong
| | - Xiaojun Bi
- College of Information and Communication Engineering, Harbin Engineering University, Harbin, China; College of Information Engineering, Minzu University of China, Beijing, China
| | - Steven Su
- School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Uphar Chamoli
- School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
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Ramakrishna VAS, Chamoli U, Rajan G, Mukhopadhyay SC, Prusty BG, Diwan AD. Smart orthopaedic implants: A targeted approach for continuous postoperative evaluation in the spine. J Biomech 2020; 104:109690. [PMID: 32139096 DOI: 10.1016/j.jbiomech.2020.109690] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/17/2020] [Accepted: 02/23/2020] [Indexed: 11/16/2022]
Abstract
Real-time health monitoring systems are emerging in diverse medical fields, tracking biological and physiological signals for direct feedback to the user. Orthopaedics is yet to adapt to innovative trends in health monitoring. Despite an evident entry point during orthopaedic surgeries, clinicians remain unable to objectively examine the structural integrity and biomechanics in the operated region through implantable sensors. As such, postoperative advice can be non-specific and poorly guided. This perspective discusses the clinical need for load-sensing implants that address biomechanical postoperative monitoring, taking the example of spinal interbody cages. Research has attempted to establish sensing approaches in different orthopaedic settings; however, they fail to meet mechanical sensing requirements or lack in vivo translatability, especially in the spine. Polymeric flexible sensors and Microelectromechanical Systems (MEMS) have favourable attributes aligned to the required features for in vivo load-sensing, although these approaches are yet to be tested extensively in orthopaedics. While inductive powering is promising, wireless energy transfer and telemetry are areas of ongoing research. This perspective proposes a thorough understanding of the relevant biomechanics to identify the pertinent sensing parameters, concurrent treatment of sensing and powering aspects, and utilisation of energy harvesting for sensing and data transmission. While sensing advancements have contributed to the rise of real-time health monitoring in other fields of medicine, orthopaedics has so far been overlooked. It is the application of these innovations that will lead to the development of a new generation of 'smart' implants for continuous postoperative evaluation.
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Affiliation(s)
- Vivek A S Ramakrishna
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Kensington, New South Wales, Australia; Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, New South Wales, Australia; School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - Uphar Chamoli
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, New South Wales, Australia; School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, New South Wales, Australia.
| | - Ginu Rajan
- School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, New South Wales, Australia
| | - Subhas C Mukhopadhyay
- School of Engineering, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
| | - B Gangadhara Prusty
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, Kensington, New South Wales, Australia
| | - Ashish D Diwan
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales, Sydney, New South Wales, Australia; Spine Service, Department of Orthopaedic Surgery St. George Hospital Campus, Kogarah, New South Wales, Australia
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Ni J, Bongers A, Chamoli U, Bucci J, Graham P, Li Y. In Vivo 3D MRI Measurement of Tumour Volume in an Orthotopic Mouse Model of Prostate Cancer. Cancer Control 2019; 26:1073274819846590. [PMID: 31032634 PMCID: PMC6488786 DOI: 10.1177/1073274819846590] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Prostate cancer (CaP) is the most commonly diagnosed cancer in males in western
countries. Orthotopic implantation is considered as an ideal xenograft model for
CaP study, and noninvasive measurement of tumor volume changes is important for
monitoring responses to anticancer therapies. In this study, the T2-weighted
fast spin echo sequence magnetic resonance imaging (MRI) was performed on a CaP
orthotopic non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mouse
model weekly for 6 weeks post PC-3 CaP cell inoculation, and the fat signal was
suppressed using a chemical shift-selective pulse. Subsequently, the MRI data
were imported into the image processing software Avizo Standard and stacked into
three-dimensional (3D) volumes. Our results demonstrate that MRI, combined with
3D reconstruction, is a feasible and sensitive method to assess tumor growth in
a PC-3 orthotopic CaP mouse model and this established monitoring approach is
promising for longitudinal observation of CaP xenograft development after
anticancer therapy in vivo. Further investigation is needed to
validate this protocol in a larger cohort of mice to generate enough statistical
power.
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Affiliation(s)
- Jie Ni
- 1 Cancer Care Centre, St George Hospital, Kogarah, New South Wales, Australia.,2 St George and Sutherland Clinical School, UNSW Sydney, New South Wales, Australia
| | - Andre Bongers
- 3 Biological Resource Imaging Laboratory, UNSW Sydney, New South Wales, Australia
| | - Uphar Chamoli
- 4 Spine Service, Department of Orthopaedic Surgery, St George and Sutherland Clinical School, UNSW Sydney, Kogarah, New South Wales, Australia.,5 School of Biomedical Engineering, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Joseph Bucci
- 1 Cancer Care Centre, St George Hospital, Kogarah, New South Wales, Australia.,2 St George and Sutherland Clinical School, UNSW Sydney, New South Wales, Australia
| | - Peter Graham
- 1 Cancer Care Centre, St George Hospital, Kogarah, New South Wales, Australia.,2 St George and Sutherland Clinical School, UNSW Sydney, New South Wales, Australia
| | - Yong Li
- 1 Cancer Care Centre, St George Hospital, Kogarah, New South Wales, Australia.,2 St George and Sutherland Clinical School, UNSW Sydney, New South Wales, Australia.,6 School of Basic Medical Sciences, Zhengzhou University, Henan, China
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Sritharan K, Chamoli U, Kuan J, Diwan AD. Assessment of degenerative cervical stenosis on T2-weighted MR imaging: sensitivity to change and reliability of mid-sagittal and axial plane metrics. Spinal Cord 2019; 58:238-246. [PMID: 31558777 DOI: 10.1038/s41393-019-0358-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/18/2019] [Accepted: 09/05/2019] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN A retrospective cross-sectional study. OBJECTIVE To assess the sensitivity to change and reliability of various mid-sagittal and axial plane metrics in the assessment of patients with single-level degenerative cervical stenosis on T2-weighted MR imaging. SETTING A diagnostic MR imaging facility in Sydney (Australia). METHODS We retrospectively reviewed T2-weighted MR images of 85 consecutive patients (48 M and 37 F) with single-level degenerative cervical stenosis. Canal compromise and cord compression were evaluated using three mid-sagittal plane metrics (M1, M2, and M3) and two axial plane metrics (M4 and M5), at the level of stenosis and nonstenotic cephalad and caudal levels (controls). Sensitivity to change (SC) for each metric was evaluated as the percentage deviation of the measured value from the estimated normal value based on cephalad and caudal controls. Reliability for each metric was evaluated using intraclass correlation coefficients. RESULTS Degenerative cervical stenosis showed a bimodal distribution peaking at C5-6 (n = 32) and C3-4 (n = 29) levels. The changes in the canal and cord geometry along the rostrocaudal axis were inconsistent. Across all individual subjects (reflecting a range of stenosis severity), M3 (-32.87% ± 10.60%) was more sensitive to change compared with M1 (16.64% ± 16.48%) and M2 (-23.95% ± 11.12%). Similarly, M4 (-24.62% ± 12.17%) was more sensitive to change compared with M5 (-6.71% ± 11.08%). The level of reliability was "moderate" to "excellent" for mid-sagittal plane measurements, and "poor" to "excellent" for axial plane measurements. CONCLUSION Changes in canal dimensions in the mid-sagittal plane and cord shape in the axial plane are sensitive indicators of degenerative cervical stenosis on T2-weighted MR images.
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Affiliation(s)
- Keerthana Sritharan
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia
| | - Uphar Chamoli
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia. .,School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
| | - Jeffrey Kuan
- St George MRI, Kirk Place, 1/15 Kensington Street, Kogarah, Sydney, NSW, 2217, Australia
| | - Ashish D Diwan
- Spine Labs, St. George & Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia
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Sheldrick K, Chamoli U, Masuda K, Miyazaki S, Kato K, Diwan AD. A novel magnetic resonance imaging postprocessing technique for the assessment of intervertebral disc degeneration-Correlation with histological grading in a rabbit disc degeneration model. JOR Spine 2019; 2:e1060. [PMID: 31572977 PMCID: PMC6764792 DOI: 10.1002/jsp2.1060] [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] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 06/14/2019] [Accepted: 06/17/2019] [Indexed: 11/09/2022] Open
Abstract
INTRODUCTION Estimation of intervertebral disc degeneration on magnetic resonance imaging (MRI) is challenging. Qualitative schemes used in clinical practice correlate poorly with pain and quantitative techniques have not entered widespread clinical use. METHODS As part of a prior study, 25 New Zealand white rabbits underwent annular puncture to induce disc degeneration in 50 noncontiguous lumbar discs. At 16 weeks, the animals underwent multi-echo T2 MRI scanning and were euthanized. The discs were stained and examined histologically. Quantitative T2 relaxation maps were prepared using the nonlinear least squares method. Decay Variance maps were created using a novel technique of aggregating the deviation in the intensity of each echo signal from the expected intensity based on the previous rate of decay. RESULTS Decay Variance maps showed a clear and well demarcated nucleus pulposus with a consistent rate of decay (low Decay Variance) in healthy discs that showed progressively more variable decay (higher Decay Variance) with increasing degeneration. Decay Variance maps required significantly less time to generate (1.0 ± 0.0 second) compared with traditional T2 relaxometry maps (5 (±0.9) to 1788.9 (±116) seconds). Histology scores correlated strongly with Decay Variance scores (r = 0.82, P < .01) and weakly with T2 signal intensity (r = 0.32, P < .01) and quantitative T2 relaxometry (r = 0.39, P < .01). Decay Variance had superior sensitivity and specificity for the detection of degenerate discs when compared to T2 signal intensity or Quantitative T2 mapping. CONCLUSION Our results show that using a multi-echo T2 MRI sequence, Decay Variance can quantitatively assess disc degeneration more accurately and with less image-processing time than quantitative T2 relaxometry in a rabbit disc puncture model. The technique is a viable candidate for quantitative assessment of disc degeneration on MRI scans. Further validation on human subjects is needed.
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Affiliation(s)
- Kyle Sheldrick
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical SchoolUniversity of New South WalesSydneyNew South WalesAustralia
| | - Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical SchoolUniversity of New South WalesSydneyNew South WalesAustralia
- School of Biomedical Engineering, Faculty of Engineering & Information TechnologyUniversity of Technology SydneySydneyNew South WalesAustralia
| | - Koichi Masuda
- Department of Orthopaedic SurgeryUniversity of CaliforniaSan DiegoCalifornia
| | - Shingo Miyazaki
- Department of Orthopaedic SurgeryUniversity of CaliforniaSan DiegoCalifornia
| | - Kenji Kato
- Department of Orthopaedic SurgeryUniversity of CaliforniaSan DiegoCalifornia
| | - Ashish D. Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical SchoolUniversity of New South WalesSydneyNew South WalesAustralia
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Chamoli U, Umali J, Kleuskens MWA, Chepurin D, Diwan AD. Morphological characteristics of the kangaroo lumbar intervertebral discs and comparison with other animal models used in spine research. Eur Spine J 2019; 29:652-662. [PMID: 31240440 DOI: 10.1007/s00586-019-06044-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 06/04/2019] [Accepted: 06/18/2019] [Indexed: 11/27/2022]
Abstract
PURPOSE Animal models are frequently used to elucidate pathomechanism and pathophysiology of various disorders of the human intervertebral disc (IVD) and also to develop therapeutic approaches. Here we report morphological characteristics of the kangaroo lumbar IVDs and compare them with other animal models used in spine research. METHODS Twenty-five fresh-frozen cadaveric lumbar spines (T12-S1) derived from kangaroo carcases (Macropus giganteus) of undetermined age were first scanned in a C-Arm X-ray machine. A photograph of the axial section of the disc including a calibrated metric scale was also acquired. The digital radiographs and photographs were processed in ImageJ to determine the axial and sagittal plane dimensions for the whole disc (WD) and the nucleus pulposus (NP) and the mid-sagittal disc height for all the lumbar levels. RESULTS Our results suggest that the L6-S1 IVD in kangaroos is distinctly large compared with the upper lumbar IVDs. Based on previously published data, human lumbar IVDs are the largest of all the animal IVDs used in spine research, with camelid cervical IVDs being the closest relative in absolute dimensions (llamas: 78% in disc height, 40% in WD volume, and 38% in NP volume). Kangaroo L6-S1 IVD was approximately 51% in height, 20% in WD volume, and 20% in NP volume of the human lumbar IVD. CONCLUSIONS We conclude that morphological similarities exist between a kangaroo and human lumbar IVD, especially with the lima bean shape in the axial plane, wedge shape in the sagittal plane, convexity at the cephalad endplates, and percentage volume occupied by the NP in the IVD. These slides can be retrieved under Electronic Supplementary Material.
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Affiliation(s)
- Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St. George and Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia.
- Faculty of Engineering and Information Technology, School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
| | - Jose Umali
- Spine Service, Department of Orthopaedic Surgery, St. George and Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia
| | - Meike W A Kleuskens
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Daniel Chepurin
- Spine Service, Department of Orthopaedic Surgery, St. George and Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia
- Faculty of Medicine Nursing and Health Sciences, Monash University, Clayton, Melbourne, VIC, 3168, Australia
| | - Ashish D Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George and Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia
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Ramakrishna VAS, Chamoli U, Viglione LL, Tsafnat N, Diwan AD. The Role of Sacral Slope in the Progression of a Bilateral Spondylolytic Defect at L5 to Spondylolisthesis: A Biomechanical Investigation Using Finite Element Analysis. Global Spine J 2018; 8:460-470. [PMID: 30258751 PMCID: PMC6149045 DOI: 10.1177/2192568217735802] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
STUDY DESIGN A biomechanical study using finite element analysis. OBJECTIVES The main objective of this study was to investigate the role of sacral slope in the progression of a L5 bilateral spondylolytic defect to spondylolisthesis. METHODS A 3-dimensional model of lumbosacral spine was built using computed tomography (CT) data procured from an anonymized healthy male subject. The segmented CT data was manipulated to generate 3 more models representing L5 bilateral spondylolytic defect with normal sacral slope (SS), sacral slope increased by 10° (SS+10), and sacral slope decreased by 10° (SS-10). The 3D models were imported into finite element modelling software Strand7 for preprocessing, running nonlinear static solves, and postprocessing of the results. RESULTS Directional biomechanical instabilities were induced in the lumbosacral spine as a result of changes in the L5-S1 disc shape secondary to the changes in sacral slope. Compared with the normal L5 lytic model, wedging of the L5-S1 disc (SS+10) resulted in a significantly greater range of motion in flexion (18% ↑) but extension motion characteristics were similar. Conversely, flattening of the L5-S1 disc (SS-10) resulted in a significantly greater range of motion in extension (16% ↑) but flexion motion characteristics were similar to that of the normal L5 lytic model. CONCLUSIONS Variations in sacral slope while preserving the L5-S1 mid-disc height and orientation of the L5 vertebra resulted in variations in the L5-S1 disc shape. The results suggest that for such extremities in the L5-S1 disc shape different pathomechanisms exist for the progression of the L5 lytic defect to spondylolisthesis.
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Affiliation(s)
- Vivek A. S. Ramakrishna
- Spine Service, Department of Orthopaedic Surgery, St. George &
Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney NSW,
Australia
- School of Biomedical Engineering, University of Technology Sydney, Ultimo
NSW, Australia
| | - Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St. George &
Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney NSW,
Australia
| | - Luke L. Viglione
- Spine Service, Department of Orthopaedic Surgery, St. George &
Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney NSW,
Australia
| | - Naomi Tsafnat
- School of Mechanical and Manufacturing Engineering, University of New South
Wales Australia, Kensington campus, Sydney NSW, Australia
| | - Ashish D. Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George &
Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney NSW,
Australia
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Ramakrishna VAS, Chamoli U, Viglione LL, Tsafnat N, Diwan AD. Mild (not severe) disc degeneration is implicated in the progression of bilateral L5 spondylolysis to spondylolisthesis. BMC Musculoskelet Disord 2018; 19:98. [PMID: 29609581 PMCID: PMC5879802 DOI: 10.1186/s12891-018-2011-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/20/2018] [Indexed: 12/01/2022] Open
Abstract
Background Spondylolytic (or lytic) spondylolisthesis is often associated with disc degeneration at the index-level; however, it is not clear if disc degeneration is the cause or the consequence of lytic spondylolisthesis. The main objective of this computed tomography based finite element modelling study was to examine the role of different grades of disc degeneration in the progression of a bilateral L5-lytic defect to spondylolisthesis. Methods High-resolution computed tomography data of the lumbosacral spine from an anonymised healthy male subject (26 years old) were segmented to build a 3D-computational model of an INTACT L1-S1 spine. The INTACT model was manipulated to generate four more models representing a bilateral L5-lytic defect and the following states of the L5-S1 disc: nil degeneration (NOR LYTIC), mild degeneration (M-DEG LYTIC), mild degeneration with 50% disc height collapse (M-DEG-COL LYTIC), and severe degeneration with 50% disc height collapse(S-COL LYTIC). The models were imported into a finite element modelling software for pre-processing, running nonlinear-static solves, and post-processing of the results. Results Compared with the baseline INTACT model, M-DEG LYTIC model experienced the greatest increase in kinematics (Fx range of motion: 73% ↑, Fx intervertebral translation: 53%↑), shear stresses in the annulus (Fx anteroposterior: 163%↑, Fx posteroanterior: 31%↑), and strain in the iliolumbar ligament (Fx: 90%↑). The S-COL LYTIC model experienced a decrease in mobility (Fx range of motion: 48%↓, Fx intervertebral translation: 69%↓) and an increase in normal stresses in the annulus (Fx Tensile: 170%↑; Fx Compressive: 397%↑). No significant difference in results was noted between M-DEG-COL LYTIC and S-COL LYTIC models. Conclusions In the presence of a bilateral L5 spondylolytic defect, a mildly degenerate index-level disc experienced greater intervertebral motions and shear stresses compared with a severely degenerate index-level disc in flexion and extension bending motions. Disc height collapse, with or without degenerative changes in the stiffness properties of the disc, is one of the plausible re-stabilisation mechanisms available to the L5-S1 motion segment to mitigate increased intervertebral motions and shear stresses due to a bilateral L5 lytic defect. Electronic supplementary material The online version of this article (10.1186/s12891-018-2011-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vivek A S Ramakrishna
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia.,School of Biomedical Engineering, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia.
| | - Luke L Viglione
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia
| | - Naomi Tsafnat
- School of Mechanical and Manufacturing Engineering, University of New South Wales Australia, Kensington campus, Sydney, NSW, 2052, Australia
| | - Ashish D Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales Australia, Kogarah, Sydney, NSW, 2217, Australia
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15
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Sabnis AB, Chamoli U, Diwan AD. Is L5-S1 motion segment different from the rest? A radiographic kinematic assessment of 72 patients with chronic low back pain. Eur Spine J 2017; 27:1127-1135. [PMID: 29181575 DOI: 10.1007/s00586-017-5400-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 11/17/2017] [Accepted: 11/18/2017] [Indexed: 11/24/2022]
Abstract
PURPOSE The relationship between biomechanical instability and degenerative changes in the lumbar spine in chronic low back pain (CLBP) patients remains controversial. The main objective of this retrospective radiographical study was to evaluate changes in kinematics at different lumbar levels (in particular the L5-S1 level) with progressive grades of disc degeneration and facet joint osteoarthritis in CLBP patients. METHODS Using standing neutral and dynamic flexion/extension (Fx/Ex) radiographs of the lumbar spine, in vivo segmental kinematics at L1-L2 through L5-S1 were evaluated in 72 consecutive CLBP patients. Disc degeneration was quantified using changes in signal intensity and central disc height on mid-sagittal T2-weighted magnetic resonance (MR) scans. Additionally, the presence or absence of facet joint osteoarthritis was noted on T2-weighted axial MR scans. RESULTS Disc degeneration and facet joint osteoarthritis occurred independent of each other at the L5-S1 level (p = 0.188), but an association was observed between the two at L4-L5 (p < 0.001) and L3-L4 (p < 0.05) levels. In the absence of facet joint osteoarthritis, the L5-S1 segment showed a greater range of motion (ROM) in Ex (3.3° ± 3.6°) and a smaller ROM in Fx (0.6° ± 4.2°) compared with the upper lumbar levels (p < 0.05), but the differences diminished in the presence of it. In the absence of facet joint osteoarthritis, no change in L5-S1 kinematics was observed with progressive disc degeneration, but in its presence, restabilisation of the L5-S1 segment was observed between mild and severe disc degeneration states. CONCLUSION The L5-S1 motion segment exhibited unique degenerative and kinematic characteristics compared with the upper lumbar motion segments. Disc degeneration and facet joint osteoarthritis occurred independent of each other at the L5-S1 level, but not at the other lumbar levels. Severe disc degeneration in the presence of facet joint osteoarthritis biomechanically restabilised the L5-S1 motion segment.
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Affiliation(s)
- Ashutosh B Sabnis
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales, Kogarah, Sydney, NSW, 2217, Australia
| | - Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales, Kogarah, Sydney, NSW, 2217, Australia.
| | - Ashish D Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales, Kogarah, Sydney, NSW, 2217, Australia
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Abstract
STUDY DESIGN A systematic review. OBJECTIVE The objective of this study was to determine the safety and efficacy of stand-alone anterior lumbar interbody fusion (sa-ALIF) for the treatment of symptomatic isthmic spondylolisthesis of L5-S1 by assessing the level of available clinical and radiographic evidence. METHODS A systematic review utilizing Medline, Embase, and Scopus online databases was undertaken. Clinical, radiographic, and adverse outcome data were extracted for the relevant isthmic spondylolisthesis cases with the intention of undertaking a meta-analysis. RESULTS The database search between January 1980 and December 2015 yielded 23 articles that concerned sa-ALIF for isthmic spondylolisthesis of L5-S1. Only in 9 of the 23 articles data could be extracted specific to sa-ALIF for isthmic spondylolisthesis of L5-S1. There was considerable inconsistency in the standards for reporting outcomes of the surgery due to which meta-analysis could not be undertaken, and hence each article was reviewed. CONCLUSIONS There was insufficient evidence to support the safety and efficacy of sa-ALIF for the treatment of isthmic spondylolisthesis of L5-S1. Although sa-ALIF is widely documented in the literature, there was insufficient evidence to support its use in treating this specific pathology. The unique pathological and anatomical situation that isthmic spondylolisthesis of L5-S1 presents must be recognized and its treatment with sa-ALIF should be well thought out.
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Affiliation(s)
- Luke L. Viglione
- Spine Service, St. George & Sutherland Clinical School, The University of New South Wales, Kogarah, New South Wales, Australia
| | - Uphar Chamoli
- Spine Service, St. George & Sutherland Clinical School, The University of New South Wales, Kogarah, New South Wales, Australia,School of Mechanical & Manufacturing Engineering, Kensington campus, The University of New South Wales, Sydney, New South Wales, Australia,Uphar Chamoli, The Orthopaedic Research Institute, 4-10 South Street, Level 2—Research and Education Building, St. George Public Hospital, Sydney, New South Wales 2217, Australia.
| | - Ashish D. Diwan
- Spine Service, St. George & Sutherland Clinical School, The University of New South Wales, Kogarah, New South Wales, Australia
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Chamoli U, Korkusuz MH, Sabnis AB, Manolescu AR, Tsafnat N, Diwan AD. Global and segmental kinematic changes following sequential resection of posterior osteoligamentous structures in the lumbar spine: An in vitro biomechanical investigation using pure moment testing protocols. Proc Inst Mech Eng H 2016; 229:812-21. [PMID: 26503842 DOI: 10.1177/0954411915612503] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [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: 11/15/2022]
Abstract
Lumbar spinal surgeries may compromise the integrity of posterior osteoligamentous structures implicating mechanical stability. Circumstances necessitating a concomitant surgery to achieve restabilisation are not well understood. The main objective of this in vitro study was to quantify global and segmental (index and adjacent levels) kinematic changes in the lumbar spine following sequential resection of the posterior osteoligamentous structures using pure moment testing protocols. Six fresh frozen cadaveric kangaroo lumbar spines (T12-S1) were tested under a bending moment in flexion-extension, bilateral bending, and axial torsion in a 6-degree-of-freedom Kinematic Spine Simulator. Specimens were tested in the following order: intact state (D0), after interspinous and supraspinous ligaments transection between L4 and L5 (D1), further after a total bilateral facetectomy between L4 and L5 (D2). Segmental motions at the cephalad, damaged, and caudal levels were recorded using an infrared-based motion tracking device. Following D1, no significant change in the global range of motion was observed in any of the bending planes. Following D2, a significant increase in the global range of motion from the baseline (D0) was observed in axial torsion (median normalised change +20%). At the damaged level, D2 resulted in a significant increase in the segmental range of motion in flexion-extension (+77%) and axial torsion (+492%). Additionally, a significant decrease in the segmental range of motion in axial torsion (-35%) was observed at the caudal level following D2. These results suggest that a multi-segment lumbar spine acts as a mechanism for transmitting motions, and that a compromised joint may significantly alter motion transfer to adjacent segments. We conclude that the interspinous and supraspinous ligaments play a modest role in restricting global spinal motions within physiologic limits. Following interspinous and supraspinous ligaments transection, a total bilateral facetectomy resulted in a significant increase in axial torsion motion, both at global and damaged levels, accompanied with a compensatory decrease in motion at the caudal level.
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Affiliation(s)
- Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St George & Sutherland Clinical School, University of New South Wales Australia, Sydney, NSW, Australia School of Mechanical and Manufacturing Engineering, University of New South Wales Australia, Sydney, NSW, Australia
| | - Mert H Korkusuz
- Spine Service, Department of Orthopaedic Surgery, St George & Sutherland Clinical School, University of New South Wales Australia, Sydney, NSW, Australia
| | - Ashutosh B Sabnis
- Spine Service, Department of Orthopaedic Surgery, St George & Sutherland Clinical School, University of New South Wales Australia, Sydney, NSW, Australia
| | - Andrei R Manolescu
- Spine Service, Department of Orthopaedic Surgery, St George & Sutherland Clinical School, University of New South Wales Australia, Sydney, NSW, Australia
| | - Naomi Tsafnat
- School of Mechanical and Manufacturing Engineering, University of New South Wales Australia, Sydney, NSW, Australia
| | - Ashish D Diwan
- Spine Service, Department of Orthopaedic Surgery, St George & Sutherland Clinical School, University of New South Wales Australia, Sydney, NSW, Australia
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Chamoli U, Chen AS, Diwan AD. Interpedicular kinematics in an in vitro biomechanical assessment of a bilateral lumbar spondylolytic defect. Clin Biomech (Bristol, Avon) 2014; 29:1108-15. [PMID: 25454471 DOI: 10.1016/j.clinbiomech.2014.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [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: 07/31/2014] [Revised: 10/06/2014] [Accepted: 10/06/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND A spondylolytic defect in lumbar vertebra is a common condition during early childhood and adolescence, and is considered a precursor to spondylolisthesis. This study examined whether a bilateral spondylolytic defect in lumbar spine intrinsically results in increased intervertebral translations during different bending motions. METHODS Seven fresh frozen cadaveric kangaroo lumbar (L1-L6) spine specimens were tested in a kinematic spine simulator; first in their intact state, followed by creating a bilateral spondylolytic defect at L4 and retesting. In addition to recording global and segmental range of motions, the pedicles at L3, L4, and L5 vertebrae were digitized bilaterally and virtually tracked throughout testing. Interpedicular kinematic metrics were employed to capture any changes in translatory motions during flexion-extension, bilateral bending, and axial torsion testing modes. FINDINGS Following the defect, range of motion at the defect level (L4-L5) increased significantly in all the three motion planes. At L4-L5, normalized interpedicular displacement increased significantly in flexion-extension (median change +156%) and bilateral bending (median change +58%) motions, but changes in bending-plane and out-of-plane intervertebral translations were not significant in any of the testing modes. INTERPRETATION In the absence of any significant changes in bending-plane and out-of-plane intervertebral translations at L4-L5, changes in interpedicular displacement would directly correspond with the stretching of posterior annulus of the L4-L5 intervertebral disc. A bilateral spondylolytic defect at L4 may result in significant overstretching of the posterior annulus of the L4-L5 disc during flexion-extension and bilateral bending motions.
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Affiliation(s)
- Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales, Kogarah, Sydney, NSW 2217, Australia; School of Mechanical and Manufacturing Engineering, University of New South Wales, Kensington campus, Sydney, NSW 2052, Australia.
| | - Alan S Chen
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales, Kogarah, Sydney, NSW 2217, Australia
| | - Ashish D Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George & Sutherland Clinical School, University of New South Wales, Kogarah, Sydney, NSW 2217, Australia
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Aquilina P, Parr WCH, Chamoli U, Wroe S. Finite element analysis of patient-specific condyle fracture plates: a preliminary study. Craniomaxillofac Trauma Reconstr 2014; 8:111-6. [PMID: 26000081 DOI: 10.1055/s-0034-1395385] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [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: 04/13/2014] [Accepted: 06/03/2014] [Indexed: 10/24/2022] Open
Abstract
Various patterns of internal fixation of mandibular condyle fractures have been proposed in the literature. This study investigates the stability of two patient-specific implants (PSIs) for the open reduction and internal fixation of a subcondylar fracture of the mandible. A subcondylar fracture of a mandible was simulated by a series of finite element models. These models contained approximately 1.2 million elements, were heterogeneous in bone material properties, and also modeled the muscles of mastication. Models were run assuming linear elasticity and isotropic material properties for bone. The stability and von Mises stresses of the simulated condylar fracture reduced with each of the PSIs were compared. The most stable of the plate configurations examined was PSI 1, which had comparable mechanical performance to a single 2.0 mm straight four-hole plate.
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Affiliation(s)
- Peter Aquilina
- Department of OMFS, Westmead Hospital, Sydney, Australia ; Department of Plastic and Reconstructive Surgery, The Nepean Hospital, Kingswood, Sydney, Australia ; Computational Biomechanics Research Group, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia
| | - William C H Parr
- Surgical and Orthopaedic Research Laboratory, Prince of Wales Hospital, Sydney, New South Wales, Australia
| | - Uphar Chamoli
- Department of Orthopaedic Surgery, St. George Hospital Clinical School, University of New South Wales, Sydney, New South Wales, Australia ; School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, New South Wales, Australia
| | - Stephen Wroe
- Computational Biomechanics Research Group, Zoology Division, School of Environmental and Rural Science, University of New England, Armidale, Australia
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Aquilina P, Parr WCH, Chamoli U, Wroe S, Clausen P. A Biomechanical Comparison of Three 1.5-mm Plate and Screw Configurations and a Single 2.0-mm Plate for Internal Fixation of a Mandibular Condylar Fracture. Craniomaxillofac Trauma Reconstr 2014; 7:218-23. [PMID: 25136411 DOI: 10.1055/s-0034-1375172] [Citation(s) in RCA: 3] [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] [Received: 08/12/2013] [Accepted: 10/15/2013] [Indexed: 10/25/2022] Open
Abstract
The most stable pattern of internal fixation for mandibular condyle fractures is an area of ongoing discussion. This study investigates the stability of three patterns of plate fixation using readily available, commercially pure titanium implants. Finite element models of a simulated mandibular condyle fracture were constructed. The completed models were heterogeneous in bone material properties, contained approximately 1.2 million elements and incorporated simulated jaw adducting musculature. Models were run assuming linear elasticity and isotropic material properties for bone. No human subjects were involved in this investigation. The stability of the simulated condylar fracture reduced with the different implant configurations, and the von Mises stresses of a 1.5-mm X-shaped plate, a 1.5-mm rectangular plate, and a 1.5-mm square plate (all Synthes (Synthes GmbH, Zuchwil, Switzerland) were compared. The 1.5-mm X plate was the most stable of the three 1.5-mm profile plate configurations examined and had comparable mechanical performance to a single 2.0-mm straight four-hole plate. This study does not support the use of rectangular or square plate patterns in the open reduction and internal fixation of mandibular condyle fractures. It does provide some support for the use of a 1.5-mm X plate to reduce condylar fractures in selected clinical cases.
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Affiliation(s)
- Peter Aquilina
- Department of Maxillofacial Surgery, Westmead Hospital, Westmead, New South Wales, Australia
| | - William C H Parr
- Computational Biomechanics Research Group, School of Biological, Earth and Environmental Sciences, Sydney, New South Wales, Australia
| | - Uphar Chamoli
- Department of Orthopaedic Surgery, Spine Service, St. George Hospital Clinical School, University of New South Wales, Sydney, Australia
| | - Stephen Wroe
- Division of Zoology, School of Environmental and Rural Science, Armidale, Australia
| | - Philip Clausen
- School of Engineering, University of Newcastle, Newcastle, Australia
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Chamoli U, Diwan AD, Tsafnat N. Pedicle screw-based posterior dynamic stabilizers for degenerative spine:In vitrobiomechanical testing and clinical outcomes. J Biomed Mater Res A 2013; 102:3324-40. [DOI: 10.1002/jbm.a.34986] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 09/25/2013] [Accepted: 09/30/2013] [Indexed: 01/28/2023]
Affiliation(s)
- Uphar Chamoli
- Spine Service, Department of Orthopaedic Surgery, St. George Hospital Clinical School; University of New South Wales; Kogarah Sydney NSW 2217 Australia
- School of Mechanical and Manufacturing Engineering; University of New South Wales; Kensington Campus Sydney NSW 2052 Australia
| | - Ashish D. Diwan
- Spine Service, Department of Orthopaedic Surgery, St. George Hospital Clinical School; University of New South Wales; Kogarah Sydney NSW 2217 Australia
| | - Naomi Tsafnat
- School of Mechanical and Manufacturing Engineering; University of New South Wales; Kensington Campus Sydney NSW 2052 Australia
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Wroe S, Chamoli U, Parr WCH, Clausen P, Ridgely R, Witmer L. Comparative Biomechanical Modeling of Metatherian and Placental Saber-Tooths: A Different Kind of Bite for an Extreme Pouched Predator. PLoS One 2013; 8:e66888. [PMID: 23840547 PMCID: PMC3694156 DOI: 10.1371/journal.pone.0066888] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 05/10/2013] [Indexed: 11/19/2022] Open
Abstract
Questions surrounding the dramatic morphology of saber-tooths, and the presumably deadly purpose to which it was put, have long excited scholarly and popular attention. Among saber-toothed species, the iconic North American placental, Smilodon fatalis, and the bizarre South American sparassodont, Thylacosmilus atrox, represent extreme forms commonly forwarded as examples of convergent evolution. For S. fatalis, some consensus has been reached on the question of killing behaviour, with most researchers accepting the canine-shear bite hypothesis, wherein both head-depressing and jaw closing musculatures played a role in delivery of the fatal bite. However, whether, or to what degree, T. atrox may have applied a similar approach remains an open question. Here we apply a three-dimensional computational approach to examine convergence in mechanical performance between the two species. We find that, in many respects, the placental S. fatalis (a true felid) was more similar to the metatherian T. atrox than to a conical-toothed cat. In modeling of both saber-tooths we found that jaw-adductor-driven bite forces were low, but that simulations invoking neck musculature revealed less cranio-mandibular stress than in a conical-toothed cat. However, our study also revealed differences between the two saber-tooths likely reflected in the modus operandi of the kill. Jaw-adductor-driven bite forces were extremely weak in T. atrox, and its skull was even better-adapted to resist stress induced by head-depressors. Considered together with the fact that the center of the arc described by the canines was closer to the jaw-joint in Smilodon, our results are consistent with both jaw-closing and neck musculature playing a role in prey dispatch for the placental, as has been previously suggested. However, for T. atrox, we conclude that the jaw-adductors probably played no major part in the killing bite. We propose that the metatherian presents a more complete commitment to the already extreme saber-tooth 'lifestyle'.
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Affiliation(s)
- Stephen Wroe
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
- School of Engineering, University of Newcastle, Callaghan, NSW, Australia
- * E-mail:
| | - Uphar Chamoli
- School of Engineering, University of Newcastle, Callaghan, NSW, Australia
- St. George Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - William C. H. Parr
- School of Engineering, University of Newcastle, Callaghan, NSW, Australia
| | - Philip Clausen
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Ryan Ridgely
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, United States of America
| | - Lawrence Witmer
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, United States of America
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Aquilina P, Chamoli U, Parr WC, Clausen PD, Wroe S. Finite element analysis of three patterns of internal fixation of fractures of the mandibular condyle. Br J Oral Maxillofac Surg 2013; 51:326-31. [DOI: 10.1016/j.bjoms.2012.08.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 08/15/2012] [Indexed: 11/26/2022]
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Oldfield CC, McHenry CR, Clausen PD, Chamoli U, Parr WCH, Stynder DD, Wroe S. Finite element analysis of ursid cranial mechanics and the prediction of feeding behaviour in the extinct giant Agriotherium africanum. J Zool (1987) 2011. [DOI: 10.1111/j.1469-7998.2011.00862.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C. C. Oldfield
- Mechanical Engineering; School of Engineering; The University of Newcastle; Newcastle; NSW; Australia
| | - C. R. McHenry
- Department of Anatomy and Developmental Biology; School of Biomedical Sciences; Monash University; Clayton; Vic.; Australia
| | - P. D. Clausen
- Mechanical Engineering; School of Engineering; The University of Newcastle; Newcastle; NSW; Australia
| | - U. Chamoli
- School of Biological, Environmental and Earth Sciences; University of New South Wales; Sydney; NSW; Australia
| | - W. C. H. Parr
- School of Biological, Environmental and Earth Sciences; University of New South Wales; Sydney; NSW; Australia
| | - D. D. Stynder
- Department of Archaeology; Faculty of Science; University of Cape Town; Rondebosch; South Africa
| | - S. Wroe
- School of Biological, Environmental and Earth Sciences; University of New South Wales; Sydney; NSW; Australia
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Attard M, Chamoli U, Ferrara T, Rogers T, Wroe S. Skull mechanics and implications for feeding behaviour in a large marsupial carnivore guild: the thylacine, Tasmanian devil and spotted-tailed quoll. J Zool (1987) 2011. [DOI: 10.1111/j.1469-7998.2011.00844.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Chamoli U, Wroe S. Allometry in the distribution of material properties and geometry of the felid skull: why larger species may need to change and how they may achieve it. J Theor Biol 2011; 283:217-26. [PMID: 21651916 DOI: 10.1016/j.jtbi.2011.05.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 05/12/2011] [Accepted: 05/16/2011] [Indexed: 11/26/2022]
Abstract
Extant members of the cat family (Felidae) have been considered behaviourally and morphologically conservative, i.e., despite great differences in size, there is relatively little variation in either the shape of the felid skull and dentition across species, or in the way in which these structures are used to kill and dismember prey. Consequently felids have been considered an appropriate focus for a number of investigations into the influence of allometry on craniomandibular mechanics and morphology. However, although previous treatments have considered the role of shape, they have not investigated the influence of differences in the distribution of relatively stiff cortical and more compliant cancellous bone on performance. Here, using models that incorporate material properties for both cortical and cancellous bone, we apply three-dimensional (3D) finite element analysis (FEA) to models representing the skulls of seven extant felid species. Our objectives being to determine allometric trends regarding both overall geometry and the relative distributions of cortical and cancellous bone tissue. We also more comprehensively assess variation in the efficiency with which muscular force is converted to bite force and the capacity to resist associated stresses. Our results show that the cheetah (Acinonyx jubatus) may be exceptional regarding both the efficiency with which muscular force is converted to bite force and the distribution of stress. We found a negative allometric trend between cortical bone volume and total skull bone volume, and positive allometry between the total skull bone volume and skull surface area. Results gained from mathematical modelling of beam analogies suggest that these trends reflect a need for larger species to respond to physical challenges associated with increased size, and, that changes in skull shape, bone composition, or a combination of both may be required to accommodate these challenges. With geometrical scaling stress increases by the same factor, and displacement by the same factor squared, but the ultimate failure stress of the material is invariant. We find that as species become larger, overall skull bone volume relative to surface area increases by adding a higher proportion of less dense and more compliant cancellous bone. This results in an increased cross-sectional area and second moment of inertia, which acts to reduce the overall stresses. An overall saving in mass is a likely additional consequence. Although we do find evidence that skull stiffness does diminish with size, we also argue that this is at least in part mitigated through the influence of these allometric trends. We further suggest that these trends and the explanations for them may be universal for vertebrates.
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Affiliation(s)
- Uphar Chamoli
- Computational Biomechanics Research Group, Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington campus, Sydney, NSW 2052, Australia
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Abstract
Diminished bite force has been considered a defining feature of modern Homo sapiens, an interpretation inferred from the application of two-dimensional lever mechanics and the relative gracility of the human masticatory musculature and skull. This conclusion has various implications with regard to the evolution of human feeding behaviour. However, human dental anatomy suggests a capacity to withstand high loads and two-dimensional lever models greatly simplify muscle architecture, yielding less accurate results than three-dimensional modelling using multiple lines of action. Here, to our knowledge, in the most comprehensive three-dimensional finite element analysis performed to date for any taxon, we ask whether the traditional view that the bite of H. sapiens is weak and the skull too gracile to sustain high bite forces is supported. We further introduce a new method for reconstructing incomplete fossil material. Our findings show that the human masticatory apparatus is highly efficient, capable of producing a relatively powerful bite using low muscle forces. Thus, relative to other members of the superfamily Hominoidea, humans can achieve relatively high bite forces, while overall stresses are reduced. Our findings resolve apparently discordant lines of evidence, i.e. the presence of teeth well adapted to sustain high loads within a lightweight cranium and mandible.
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Affiliation(s)
- Stephen Wroe
- Computational Biomechanics Research Group, Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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