Abstract
Animal models have been commonly used for in vivo and in vitro spinal research. However, the extent to which animal models resemble the human spine has not been well known. We conducted a systematic review to compare the morphometric features of vertebrae between human and animal species, so as to give some suggestions on how to choose an appropriate animal model in spine research. A literature search of all English language peer-reviewed publications was conducted using PubMed, OVID, Springer and Elsevier (Science Direct) for the years 1980–2008. Two reviewers extracted data on the anatomy of large animal spines from the identified articles. Each anatomical study of animals had to include at least three vertebral levels. The anatomical data from all animal studies were compared with the existing data of the human spine in the literature. Of the papers retrieved, seven were included in the review. The animals in the studies involved baboon, sheep, porcine, calf and deer. Distinct anatomical differences of vertebrae were found between the human and each large animal spine. In cervical region, spines of the baboon and human are more similar as compared to other animals. In thoracic and lumbar regions, the mean pedicle height of all animals was greater than the human pedicles. There was similar mean pedicle width between animal and the human specimens, except in thoracic segments of sheep. The human spinal canal was wider and deeper in the anteroposterior plane than any of the animals. The mean human vertebral body width and depth were greater than that of the animals except in upper thoracic segments of the deer. However, the mean vertebral body height was lower than that of all animals. This paper provides a comprehensive review to compare vertebrae geometries of experimental animal models to the human vertebrae, and will help for choosing animal model in vivo and in vitro spine research. When the animal selected for spine research, the structural similarities and differences found in the animal studies must be kept in mind.
Introduction
To date, the thoracolumbar spine is one of the lesser explored segments of the equine locomotion apparatus. The reasons are multifarious. It consists of multiple spinal articulations with little individual range of motion and thick epaxial spinal musculature (1), which make it relatively difficult to obtain clinically applicable information.
Various large animals, such as pig, calf, sheep, baboon, deer, goat and dog spines as models have been used for in vivo and in vitro spinal research [, , , , , , , ]. In vitro models consisting of cadaveric spine specimens are useful in providing basic understanding of the functioning of the spine. In vivo models provide the means to model living phenomena, such as fusion, development of disc degeneration, instability and adaptive responses in segments adjacent to spinal instrumentation. Basically, human specimens are more suitable for these models than are animal specimens whenever anatomy, size (for instrumentation) and kinematics are important. However, there are some disadvantages in using the human model. One problem is the difficulty in obtaining fresh human specimens, especially from the younger population. Another problem with the use of human specimens is the large variation in geometry and mechanical properties due to differences in age, sex, bone quality and disc and bone degenerative changes. These disadvantages of human specimens force a search for alternative animal models; and, most in vivo and in vitro experiments have been performed in animal spines, which are more easily available and have more uniform geometrical and mechanical properties. To mimic the clinical situation, an appropriate animal should have similar characteristic anatomical dimensions of spine to those in humans as possible.
Up til now, basic studies about the anatomical suitability for several large animal spines exist [–, –, , , ]. However, in nearly all these studies, only single animal was used to do the comparative anatomical study with the human spine. Therefore, a systematic review is needed to analyze the differences and similarities of vertebrae between human and all large animals studied, so as to determine the extent to which animal models more resemble the human spine. Thus, the purpose of this study is to summarize the differences and similarities of anatomy between human and animal models, and give some suggestions on how to choose a better animal model in vivo and in vitro experiment.
Methods
![Biomechanical Spine Animal Biomechanical Spine Animal](https://i1.rgstatic.net/publication/236964673_Animal_models_in_biomechanical_spine_investigations/links/0046351a7bfc99ebed000000/largepreview.png)
PubMed, OVID, Springer and Elsevier (Science Direct) were searched using the keywords: animal(s), human, spine (spinal), lumbar, thoracic, cervical, anatomy, anatomic, anatomical, morphometry, sheep, pig (swine, porcine), calf (bovine), baboon, deer, goat (ovine) and dog (canine). The search was limited to studies on spine anatomy of large animals, published in English and in the period from January 1980 up to August 2008. References of retrieved articles and of relevant overview articles were checked to identify additional studies.
Two reviewers independently checked eligible articles on title, keywords and abstract. A consensus meeting was used to discuss disagreements. Reports on studies were included if they met the following inclusion criteria: (1) large animal used in spine research: sheep, pig, calf, baboon, deer, goat and dog, (2) anatomical study of cervical, or thoracic or lumbar spine, (3) at least three vertebral levels were measured in the study. Two reviewers then extracted data from all the included papers relating to the anatomy of animal spines. We compare the spinal anatomy of these animal models with that of human from seven anatomical parameters: vertebral body width (VBW), vertebral body depth (VBD), vertebral body height (VBH), spinal canal width (SCW), spinal canal depth (SCD), pedicle width (PW) and pedicle depth (Table 1, Fig. 1). The comparative human parameters were taken from published literature, for various regions of the spine—cervical (Panjabi et al. []), thoracic (Panjabi et al. []) and lumbar (Panjabi et al. []) were recorded.
Table 1
Abbreviation | Dimension |
---|---|
Vertebral body | |
VBW | Vertebral body width |
VBD | Vertebral body depth |
VBH | Vertebral body height |
Spinal canal | |
SCW | Spinal canal width |
SCD | Spinal canal depth |
Pedicle | |
PW | Pedicle width |
PH | Pedicle height |
Suffixes | |
a | Anterior |
p | Posterior |
u | Upper |
l | Lower |
Measurement of anatomical parameters. A vertebral body width upper (VBWu), B vertebral body width lower (VBWl), C spinal canal depth (SCD), D spinal canal width (SCW), E pedicle width (PW), F vertebral body depth (VBD), G vertebral body width (VBW), H vertebral body depth upper (VBDu), I vertebral body height anterior (VBHa), J vertebral body height posterior (VBHp), K pedicle height (PH), L vertebral body depth lower (VBDl)
Results
Among the 544 papers found, 510 papers were not considered, because they do not include any relevant anatomical information on animal spine. Furthermore, 37 papers were discarded because they did not meet the inclusion criteria mentioned above. In total, seven eligible studies were reviewed for further analysis. There was one report on baboon cervical spine [], two papers on sheep spine [, ], two papers on porcine spine [, ], one paper on calf spine [] and one paper on deer spine []. These studies are summarized in Table 2. Comparisons of each anatomical parameter of human [–], baboon [], sheep [], porcine [, ], calf [] and deer [] are shown in Figs. 2, 3, 4, 5, 6, 7, 8, 9, 1011 and Tables 3, 4, 5, 67, respectively. The sheep, porcine and deer have more than 12 thoracic vertebrae, and the human has only 12 thoracic vertebrae, therefore, we just compared the parameters from T1 to T12 between them.
Table 2
Authors | Year of publication | Animal names | Number of animals | Anatomical segments | Specimen properties | Measurement tools | Comparison of anatomical differences | Conclusions |
---|---|---|---|---|---|---|---|---|
Tominaga et al. [] | 1995 | Baboon (mean age 16.7 years) | 9 | Cervical spine | Fresh | Digitized caliper | Comparison with the values of six adult cadaver cervical spines | The geometry and anatomy of the baboon cervical spine closely resemble that of the human cervical spine |
Kandziora et al. [] | 2001 | Sheep (mean age 2 years; average weight, 64.6 ± 3.7 kg) | 20 | Cervical spine | Fresh | Digitized ruler | Comparison with 20 fresh human cadaver cervical spines | The small intergroup standard deviations and the good comparability with the human spine encourage the use of the sheep cervical spine as a model for cervical spine research |
Wilke et al. [] | 1997 | Sheep (age 3–4 years; average weight, 72.1 ± 7.3 kg) | 5 | Cervical, thoracic and lumbar spines | Fresh | Hand-held micrometer | Comparison with reported values of the human spine | Sheep spine may be a useful model for experiments related to the gross structure of the thoracic or lumbar spine, with certain limitations for the cervical spine |
Bozkus et al. [] | 2005 | Pig (age 6 months; average weight, 30 kg) | 10 | Thoracic spine | Fresh | Digitized caliper and ruler | Comparison with the values of ten human cadaver Thoracic spines | Thoracic spine from T6 toT10 probably is most similar to that in the human anatomically |
Dath et al. [] | 2007 | Pig (age 18–24 months; weight, 60–80 kg) | 6 | Lumbar spine | Fresh | Digitized caliper | Comparison with the values of six human lumbar spine specimens | Porcine lumbar vertebrae may be used as an alternative to human specimen if the anatomical differences are taken into account |
Cotterill et al. [] | 1986 | Calf (age 6–8 weeks) | 10 | Thoracic (T6 and T12) and lumbar (L3) spines | Fresh | Hand-held micrometer | Comparison with the values of ten human thoracic lumbar spine specimens` | Differences in column length and curvature were observed. These significantly different measurements were considered important factors that influence experimental results when using the bovine spine as a model |
Kumar et al. [] | 2000 | Deer (age 20–27 months; weight, 46–52 kg) | 6 | Cervical, thoracic and lumbar spines | Fresh | Hand-held micrometer | Comparison with reported values of the human spine | The deer and human vertebrae show many similarities in the lower thoracic and upper lumbar spine, although they show substantial differences in certain dimensions. The cervical spine was markedly different in comparison |
Comparisons of upper vertebral body width (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of lower vertebral body width (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of upper vertebral body depth (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of lower vertebral body depth (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of anterior vertebral body height (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of posterior vertebral body height (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of spinal canal width (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of spinal canal depth (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of pedicle width (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Comparisons of pedicle height (mean ± SD) (human [–], baboon [], sheep [, ], porcine [, ], calf [] and deer [])
Table 3
The average percent of those in the human | The change trend compared with human (from C2 to C7) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
VBWu (%) | VBWl (%) | VBDu (%) | VBDl (%) | VBHa (%) | VBHp (%) | VBWu | VBWl | VBDu | VBDl | VBHa | VBHp | |
Baboon | 45–47 | Nearly 50 | 54–61 | 54.1–77.4 | Nearly half | 82.3–59.6 | Similar | Similar | Similar | Similar | Similar | Opposite |
Sheep | 101–127 | 85–138 | 109–127 | 123–150 | Nearly two to three times | 320–167 | Opposite | Opposite | Opposite | Opposite | Opposite | Opposite |
Table 4
The average percent of those in the human | The change trend compared with human (from T1 to T12) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
VBWu (%) | VBWl (%) | VBDu (%) | VBDl (%) | VBHa (%) | VBHp (%) | VBWu | VBWl | VBDu | VBDl | VBHa | VBHp | |
Sheep | 61–85 | 81–59 | 111.4–56.7 | 103–58.8 | 1.32–1.71 times | 139–190 | Similar | Similar | Opposite | Opposite | Similar | Similar |
Deer | 98–133 (from T1 to T6), 71–91 (from T7 to T12) | 122.6–72.5 | 144.8–67.9 | 148.7–72.1 | 127–219 | 146–230 | Opposite in T1–T3, similar in T4–T12 | Opposite in T1–T3, similar in T4–T12 | Opposite | Opposite | Opposite | Similar |
Porcine | 54.8–77.1 | 52.7–71.2 | Nearly half | Nearly half | 90.3–121.3 | Nearly the same | Similar | Similar | Similar | Similar | Similar | Similar |
Table 5
The average percent of those in the human | The change trend compared with human (from L1 to L5) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
VBWu (%) | VBWl (%) | VBDu (%) | VBDl (%) | VBHa (%) | VBHp (%) | VBWu | VBWl | VBDu | VBDl | VBHa | VBHp | |
Sheep | 60.60 | 60.7–64.7 | 57.1–58.9 | 56.6–59.4 | 147–173 | 155–181 | Similar | Similar | Similar | Similar | Similar | Similar |
Deer | 74–77 | 66.0–76.9 | 71.5–64.7 | 68.7–75.6 | 1.60–1.98 times | Nearly two times | Similar | Similar | Similar | Similar | The highest is at L2 | Similar |
Porcine | 78.4–83.5 | 78.1–85.7 | 65.7–71.3 | Nearly half | 142–157 | 146.6–158.5 | Similar | Similar | Similar | Nearly the same | Similar | Similar |
Calf | 88.1 in T6, 65.6 in T12, 70.7 in L3 | 81.9 in T6, 60.8 in T12, 65 in L3 | 87.3 at T6, 68.9 at T12, 70.4 at L3 | 71.2 at T6, 67.6 at T12, 84.3 at L3 | 135 at T6, 103 at T12, 110 at L3 | 135 at T6, 103 at T12, 110 at L3 |
Table 6
The average percent of those in the human | The change trend compared with human (from C2-L5) | |||
---|---|---|---|---|
SCW (%) | SCD (%) | SCW | SCW | |
Cervical spine | ||||
Baboon | 51–61 | 71–88 | Similar | Opposite |
Sheep | 57–61 | 62–74 | Similar | The sheep SCD/human SCD increases from C3 to C7 |
Thoracic spine | ||||
Sheep | 52.2–78.8 | 45–73 | Similar | Opposite |
Deer | 71.3–106 | 77–101 | Similar | Opposite |
Porcine | 59.9–67.6 | 56.7–82.9 | Similar | Opposite |
Lumbar spine | ||||
Sheep | Nearly 50 | 44–48 | Similar | Similar in L3–L5 |
Deer | 63.7–85.9 | 72–84 | Similar | Similar in L3–L5 |
Porcine | 67.4–76.4 | 60.9–66.9 | Similar | Similar in L3–L5 |
Calf | 94.2 at T6, 86.4 at T12, 80.6 at L3 | 81.2 at T6, 75.6 at T12, 86.2 at L3 |
Table 7
The average percent of those in the human | The change trend compared with human (from C2-L5) | |||
---|---|---|---|---|
PW (%) | PH (%) | PW | PH | |
Cervical spine | ||||
Baboon | 31.6–54.9 | Nearly the same | Similar | Similar |
Sheep | Two times | Four to five times | Similar | Opposite |
Thoracic spine | ||||
Sheep | 98–198 | 146–164 | Similar in T1–T4, opposite in T4–12 | Similar |
Deer | 72–158 | 1.5–2 times | Similar | Opposite in T1–T9, similar in T10–T12 |
Porcine | 78.3–125 | 93–128 | Similar | Similar |
Lumbar spine | ||||
Sheep | 57–110 | Nearly 2 to 2.5 times | Similar | Opposite |
Deer | 55–123 | 153–238 | Similar | Opposite |
Porcine | 157–66.1 | 110–156 | Opposite | Similar |
Calf | 121 at T6, 87.5 at T12, 83.3 at L3 |
Vertebral body
In cervical region, the baboon spine is nearly half of human, and the increase trend of spine is similar to that in humans. The sheep spine is larger than human, particularly in VBH, and the trend is opposite to that in humans. In thoracic and lumbar regions, the mean human VBW and VBD are greater than that of the animals, except in upper thoracic segments of the deer; the mean VBH is lower than that of all animals (Tables 3, 4, 5; Figs. 2, 3, 4, 5, 6, 7).
Spinal canal
The human spinal canal is wider and deeper in the anteroposterior plane than any of the animals. The human is similar to the all animal model in increase trend of SCW, but the increase trend of SCD is opposite, except the sheep, deer and porcine lumbar spine (Table 6; Figs. 8, 9).
Pedicle
The mean pedicle height (PH) of all animals is greater than the human pedicles. There is similar mean PW between animal and the human specimens, except in thoracic segments of sheep (Table 7, Figs. 10, 11).
Discussion
Basic spine research and preclinical testing of new surgical methods often involve animal experiments because most tests cannot be carried out on humans or the availability of human specimens is limited. Currently, large animal models, such as sheep, pig, calf, baboon, deer, goat and dog spines have been used to substitute for human spine [, , , , , , , ]. Before using animal models, it is necessary to study how the parameters of interest differ between species to be aware of the limitations of any particular animal model and to ensure conclusions reached are applicable to human. The current review shows although qualitatively, the anatomy of the spine of these species is similar to that of human, the sizes of some parameters differ considerably, including greater VBHs, lower VBW and VBD, smaller spinal canal and greater PH. Therefore, the ideal animal model for human spine does not exist. The differences between human and quadruped spines may affect the consequences for the interpretation of experimental results. These differences and similarities should be kept in mind, when choosing an animal model for study of human spinal conditions and treatments.
Although based on such comparative data of these animal models, it is difficult to interpret, whether a certain species is most suitable to be used as the human spine, we can choose an appropriate animal model based on the factors such as, anatomy, availability and cost, etc. Kandziora et al. [] concluded that the sheep cervical spine is suitable as a model for cervical spine research. An analysis of existing data in the present study shows that only considering VBH, the baboon cervical spine is the best model to substitute for human, while the VBH of sheep cervical spine is significantly greater than that of human spine []. In terms of VBW, the trend of the sheep cervical spine is the opposite to that in humans from C2 to C7. Although the baboon cervical spine is smaller than human’s, the VBW trend is similar to human. Therefore, in cervical region, spines of the baboon and human are more similar as compared to sheep, indicating the baboon may be a better substitution for human cervical spine in anatomy, which might be their closely shared gene homology []. In lower thoracic and upper lumbar regions, deer may be used as an alternative to human specimens, if the differences are taken into consideration. Sheep spine may be a useful model for experiments related to the gross structure of the thoracic or lumbar spine, with certain limitations for the cervical spine []. The most suitable for human spine of porcine is from T6 to T10, and the lumbar spine of porcine is an alternative to human specimens. The calf is an alternative to human thoracic and lumbar specimens, if the differences are taken into consideration. When compared with human spine, another relevant issue of using animal models is difference in size, which is important for the used implants and screw lengths. The VBH is larger for most animals, which results in a larger corpectomy size. For the PH, most animal pedicles are larger than human, indicating a human pedicle screw can be used in animal models. Animals seem to be small for human cage sizes due to lower VBW and VBD. Only if we know how the parameters of interest differ between animal and human spine, experimental studies involving interbody cages, and screw–rod systems could be sized appropriately to provide meaningful results.
Although each porcine, calf, deer or sheep could be a choice of experimental animal for in vivo and in vitro experimental studies according to anatomical studies, several factors such as biomechanical property, availability, costs, breeding and growth also should be considered. The animals selected for spine in vivo research must be of an appropriate size both at the beginning and at the end of the experiment. Therefore, mature sheep model could be chosen for in vitro experimental use. Pig and calf generally are not to be considered for in vivo experimentation is that they grow too rapidly, high cost and not easy to handle. Calf model (age 6–8 weeks) in the present review study include open growth plates, and may lead to oversize vertebrae. Mature porcine (age 18–24 months) may avoid these limitations. Therefore, in stability biomechanical testing, both calf and porcine models could be selected for thoracic and lumbar spine research. However, when used as a traumatic model, the presence of open growth plates in immature calf spine specimens, which may affect the results of biomechanical experiment, have to be considered. The deer spine specimens could be an alternative to calf and porcine for human thoracic and lumbar spine, but it has the disadvantage of difficult availability and higher cost.
In all included papers, fresh specimens were evaluated anatomically, and parameters were measured using digitized caliper or hand-held micrometer. However, some limitations of the current study have to be noted. First, this study has not included bone mineralization and biomechanical properties of the specimens that may influence the choice of experimental specimens. Theoretical considerations show that the spine of the quadruped animal is mainly loaded along its long axis, just like the human spine []. However the animals have higher vertebral bone densities, thus, indicating that axial compression stress is higher than in humans []. Moreover, significant differences have been identified in flexibility testing between animal and human cadaveric specimens []. All differences of these biomechanical properties may affect the animal models as a substitute for human spine. Secondly, the present study was aimed solely at identifying published peer-reviewed English literature, so that publication bias cannot be entirely ruled out. Thirdly, the present study excluded the paper on the morphometry of a single vertebra from large animal models [, ], which may lost some information. However, we believe data from more than a single vertebra is necessary, because spinal instrumentation and implant testing are commonly at least three vertebral levels, and more important is to show the anatomical trend of the vertebrae. Finally, the present study did not make an anatomical comparison of all the segments of the animal spines to that of the humans, because of the different measurement conditions. Therefore, the anatomy of the goat and canine spines and the porcine and calf cervical spines need to be studied in the near future.
This study gives us a clear view of similarities and differences of vertebrae geometries between common experimental animal and human spines. This will be useful to choose animal model in vivo and in vitro spine research; also, when a certain animal is selected for spine research, the structural similarities and differences found in the animal model studies must be kept in mind.
Acknowledgment
This work is supported by a Grant from the China National Nature Fund (Grant no. 30700843).
Contributor Information
Sun-Ren Sheng, Email: moc.621@03328nernusgnehs.
Hua-Zi Xu, Phone: +86-577-88829799, Fax: +86-577-88879123, Email: moc.361@ux-enips.
References
Biomechanics is the study of the structure, function and motion of the mechanical aspects of biological systems, at any level from whole organisms to organs, cells and cell organelles,[1] using the methods of mechanics.[2]
- 2Subfields
- 3History
Etymology[edit]
The word 'biomechanics' (1899) and the related 'biomechanical' (1856) come from the Ancient Greek βίος bios 'life' and μηχανική, mēchanikē 'mechanics', to refer to the study of the mechanical principles of living organisms, particularly their movement and structure.[3]
Subfields[edit]
Biofluid mechanics[edit]
Biological fluid mechanics, or biofluid mechanics, is the study of both gas and liquid fluid flows in or around biological organisms. An often studied liquid biofluids problem is that of blood flow in the human cardiovascular system. Under certain mathematical circumstances, blood flow can be modelled by the Navier–Stokes equations. In vivowhole blood is assumed to be an incompressible Newtonian fluid. However, this assumption fails when considering forward flow within arterioles. At the microscopic scale, the effects of individual red blood cells become significant, and whole blood can no longer be modelled as a continuum. When the diameter of the blood vessel is just slightly larger than the diameter of the red blood cell the Fahraeus–Lindquist effect occurs and there is a decrease in wall shear stress. However, as the diameter of the blood vessel decreases further, the red blood cells have to squeeze through the vessel and often can only pass in single file. In this case, the inverse Fahraeus–Lindquist effect occurs and the wall shear stress increases.
An example of a gaseous biofluids problem is that of human respiration. Recently, respiratory systems in insects have been studied for bioinspiration for designing improved microfluidic devices.[4]
Biotribology[edit]
The main aspects of Contact mechanics and tribology are related to friction, wear and lubrication. When the two surfaces come in contact during motion i.e. rub against each other, friction, wear and lubrication effects are very important to analyze in order to determine the performance of the material. Biotribology is a study of friction, wear and lubrication of biological systems especially human joints such as hips and knees.[5] For example, femoral and tibial components of knee implant routinely rub against each other during daily activity such as walking or stair climbing. If the performance of tibial component needs to be analyzed, the principles of biotribology are used to determine the wear performance of the implant and lubrication effects of synovial fluid. In addition, the theory of contact mechanics also becomes very important for wear analysis. Additional aspects of biotribology can also include analysis of subsurface damage resulting from two surfaces coming in contact during motion, i.e. rubbing against each other, such as in the evaluation of tissue engineered cartilage.[6]
Comparative biomechanics[edit]
Comparative biomechanics is the application of biomechanics to non-human organisms, whether used to gain greater insights into humans (as in physical anthropology) or into the functions, ecology and adaptations of the organisms themselves. Common areas of investigation are Animal locomotion and feeding, as these have strong connections to the organism's fitness and impose high mechanical demands. Animal locomotion, has many manifestations, including running, jumping and flying. Locomotion requires energy to overcome friction, drag, inertia, and gravity, though which factor predominates varies with environment.[citation needed]
Comparative biomechanics overlaps strongly with many other fields, including ecology, neurobiology, developmental biology, ethology, and paleontology, to the extent of commonly publishing papers in the journals of these other fields. Comparative biomechanics is often applied in medicine (with regards to common model organisms such as mice and rats) as well as in biomimetics, which looks to nature for solutions to engineering problems.[citation needed]
Computational biomechanics[edit]
Computational biomechanics is the application of engineering computational tools, such as the Finite element method to study the mechanics of biological systems. Computational models and simulations are used to predict the relationship between parameters that are otherwise challenging to test experimentally, or used to design more relevant experiments reducing the time and costs of experiments. Mechanical modeling using finite element analysis has been used to interpret the experimental observation of plant cell growth to understand how they differentiate, for instance.[7] In medicine, over the past decade, the Finite element method has become an established alternative to in vivo surgical assessment. One of the main advantages of computational biomechanics lies in its ability to determine the endo-anatomical response of an anatomy, without being subject to ethical restrictions.[8] This has led FE modeling to the point of becoming ubiquitous in several fields of Biomechanics while several projects have even adopted an open source philosophy (e.g. BioSpine).
Continuum biomechanics[edit]
The mechanical analysis of biomaterials and biofluids is usually carried forth with the concepts of continuum mechanics. This assumption breaks down when the length scales of interest approach the order of the micro structural details of the material. One of the most remarkable characteristic of biomaterials is their hierarchical structure. In other words, the mechanical characteristics of these materials rely on physical phenomena occurring in multiple levels, from the molecular all the way up to the tissue and organ levels.[citation needed]
Biomaterials are classified in two groups, hard and soft tissues. Mechanical deformation of hard tissues (like wood, shell and bone) may be analysed with the theory of linear elasticity. On the other hand, soft tissues (like skin, tendon, muscle and cartilage) usually undergo large deformations and thus their analysis rely on the finite strain theory and computer simulations. The interest in continuum biomechanics is spurred by the need for realism in the development of medical simulation.[9]:568
Plant biomechanics[edit]
The application of biomechanical principles to plants, plant organs and cells has developed into the subfield of plant biomechanics.[10] Application of biomechanics for plants ranges from studying the resilience of crops to environmental stress[11] to development and morphogenesis at cell and tissue scale, overlapping with mechanobiology.[7]
Sports biomechanics[edit]
In sports biomechanics, the laws of mechanics are applied to human movement in order to gain a greater understanding of athletic performance and to reduce sport injuries as well. It focuses on the application of the scientific principles of mechanical physics to understand movements of action of human bodies and sports implements such as cricket bat, hockey stick and javelin etc. Elements of mechanical engineering (e.g., strain gauges), electrical engineering (e.g., digital filtering), computer science (e.g., numerical methods), gait analysis (e.g., force platforms), and clinical neurophysiology (e.g., surface EMG) are common methods used in sports biomechanics.[12]
Biomechanics in sports can be stated as the muscular, joint and skeletal actions of the body during the execution of a given task, skill and/or technique. Proper understanding of biomechanics relating to sports skill has the greatest implications on: sport's performance, rehabilitation and injury prevention, along with sport mastery. As noted by Doctor Michael Yessis, one could say that best athlete is the one that executes his or her skill the best.[13]
Other applied subfields of biomechanics include:[edit]
- Animal locomotion & Gait analysis
- Biotribology
- Biofluid mechanics
- Cardiovascular biomechanics
- Comparative biomechanics
- Computational biomechanics
- Human factors engineering & occupational biomechanics
- Implant (medicine), Orthotics & Prosthesis
- Kinesiology (kinetics + physiology)
- Musculoskeletal & orthopedic biomechanics
History[edit]
Antiquity[edit]
Aristotle, a student of Plato can be considered the first bio-mechanic, because of his work with animal anatomy. Aristotle wrote the first book on the motion of animals, De Motu Animalium, or On the Movement of Animals.[14] He not only saw animals' bodies as mechanical systems, but pursued questions such as the physiological difference between imagining performing an action and actually doing it.[15] In another work, On the Parts of Animals, he provided an accurate description of how the ureter uses peristalsis to carry urine from the kidneys to the bladder.[9]:2
With the rise of the Roman Empire, technology became more popular than philosophy and the next bio-mechanic arose. Galen (129 AD-210 AD), physician to Marcus Aurelius, wrote his famous work, On the Function of the Parts (about the human body). This would be the world’s standard medical book for the next 1,400 years.[16]
Renaissance[edit]
The next major biomechanic would not be around until 1452, with the birth of Leonardo da Vinci. Da Vinci was an artist and mechanic and engineer. He contributed to mechanics and military and civil engineering projects. He had a great understanding of science and mechanics and studied anatomy in a mechanics context. He analyzed muscle forces and movements and studied joint functions. These studies could be considered studies in the realm of biomechanics. Leonardo da Vinci studied anatomy in the context of mechanics. He analyzed muscle forces as acting along lines connecting origins and insertions, and studied joint function. Da Vinci tended to mimic some animal features in his machines. For example, he studied the flight of birds to find means by which humans could fly; and because horses were the principal source of mechanical power in that time, he studied their muscular systems to design machines that would better benefit from the forces applied by this animal.[17]
In 1543, Galen’s work, On the Function of the Parts was challenged by Andreas Vesalius at the age of 29. Vesalius published his own work called, On the Structure of the Human Body. In this work, Vesalius corrected many errors made by Galen, which would not be globally accepted for many centuries. With the death of Copernicus came a new desire to understand and learn about the world around people and how it works. On his deathbed, he published his work, On the Revolutions of the Heavenly Spheres. This work not only revolutionized science and physics, but also the development of mechanics and later bio-mechanics.[16]
Galileo Galilee, the father of mechanics and part time biomechanic was born 21 years after the death of Copernicus. Galileo spent many years in medical school and often questioned everything his professors taught. He found that the professors could not prove what they taught so he moved onto mathematics where everything had to be proven. Then, at the age of 25, he went to Pisa and taught mathematics. He was a very good lecturer and students would leave their other instructors to hear him speak, so he was forced to resign. He then became a professor at an even more prestigious school in Padua. His spirit and teachings would lead the world once again in the direction of science. Over his years of science, Galileo made a lot of biomechanical aspects known. For example, he discovered that 'animals' masses increase disproportionately to their size, and their bones must consequently also disproportionately increase in girth, adapting to loadbearing rather than mere size. [The bending strength of a tubular structure such as a bone is increased relative to its weight by making it hollow and increasing its diameter. Marine animals can be larger than terrestrial animals because the water's buoyancy [sic] relieves their tissues of weight.'[16]
Galileo Galilei was interested in the strength of bones and suggested that bones are hollow because this affords maximum strength with minimum weight. He noted that animals' bone masses increased disproportionately to their size. Consequently, bones must also increase disproportionately in girth rather than mere size. This is because the bending strength of a tubular structure (such as a bone) is much more efficient relative to its weight. Mason suggests that this insight was one of the first grasps of the principles of biological optimization.[17]
In the 16th century, Descartes suggested a philosophic system whereby all living systems, including the human body (but not the soul), are simply machines ruled by the same mechanical laws, an idea that did much to promote and sustain biomechanical study. Giovanni Alfonso Borelli embraced this idea and studied walking, running, jumping, the flight of birds, the swimming of fish, and even the piston action of the heart within a mechanical framework. He could determine the position of the human center of gravity, calculate and measured inspired and expired air volumes, and showed that inspiration is muscle-driven and expiration is due to tissue elasticity. Borelli was the first to understand that the levers of the musculoskeletal system magnify motion rather than force, so that muscles must produce much larger forces than those resisting the motion. Influenced by the work of Galileo, whom he personally knew, he had an intuitive understanding of static equilibrium in various joints of the human body well before Newton published the laws of motion.[18]
Industrial era[edit]
The next major bio-mechanic, Giovanni Alfonso Borelli, was the first to understand that “the levers of the musculature system magnify motion rather than force, so that muscles must produce much larger forces than those resisting the motion”.[16] Using the works of Galileo and building off from them, Borelli figured out the forces required for equilibrium in various joints of the human body. He even discovered the human center of gravity and air volume as well as muscle elasticity. His work is often considered the most important in the history of bio-mechanics because he made so many new discoveries that opened the way for the future generations to continue his work and studies.
It was many years after Borelli before the field of bio-mechanics made any major leaps. After that time, more and more scientists took to learning about the human body and its functions. There are not many notable scientists from the 19th or 20th century in bio-mechanics because the field is far too vast now to attribute one thing to one person. However, the field is continuing to grow every year and continues to make advances in discovering more about the human body. Because the field became so popular, many institutions and labs have opened over the last century and people continue doing research. With the Creation of the American Society of Bio-mechanics in 1977, the field continues to grow and make many new discoveries.[16]
In the 19th century Étienne-Jules Marey used cinematography to scientifically investigate locomotion. He opened the field of modern 'motion analysis' by being the first to correlate ground reaction forces with movement. In Germany, the brothers Ernst Heinrich Weber and Wilhelm Eduard Weber hypothesized a great deal about human gait, but it was Christian Wilhelm Braune who significantly advanced the science using recent advances in engineering mechanics. During the same period, the engineering mechanics of materials began to flourish in France and Germany under the demands of the industrial revolution. This led to the rebirth of bone biomechanics when the railroad engineerKarl Culmann and the anatomist Hermann von Meyer compared the stress patterns in a human femur with those in a similarly shaped crane. Inspired by this finding Julius Wolff proposed the famous Wolff's law of bone remodeling.[19]
Applications[edit]
The study of biomechanics ranges from the inner workings of a cell to the movement and development of limbs, to the mechanical properties of soft tissue,[6] and bones. Some simple examples of biomechanics research include the investigation of the forces that act on limbs, the aerodynamics of bird and insectflight, the hydrodynamics of swimming in fish, and locomotion in general across all forms of life, from individual cells to whole organisms. With growing understanding of the physiological behavior of living tissues, researchers are able to advance the field of tissue engineering, as well as develop improved treatments for a wide array of pathologies including cancer.[20][citation needed]
Biomechanics is also applied to studying human musculoskeletal systems. Such research utilizes force platforms to study human ground reaction forces and infrared videography to capture the trajectories of markers attached to the human body to study human 3D motion. Research also applies electromyography to study muscle activation, investigating muscle responses to external forces and perturbations.[21]
Biomechanics is widely used in orthopedic industry to design orthopedic implants for human joints, dental parts, external fixations and other medical purposes. Biotribology is a very important part of it. It is a study of the performance and function of biomaterials used for orthopedic implants. It plays a vital role to improve the design and produce successful biomaterials for medical and clinical purposes. One such example is in tissue engineered cartilage.[6]
It is also tied to the field of engineering, because it often uses traditional engineering sciences to analyze biological systems. Some simple applications of Newtonian mechanics and/or materials sciences can supply correct approximations to the mechanics of many biological systems. Applied mechanics, most notably mechanical engineering disciplines such as continuum mechanics, mechanism analysis, structural analysis, kinematics and dynamics play prominent roles in the study of biomechanics.[22]
Usually biological systems are much more complex than man-built systems. Numerical methods are hence applied in almost every biomechanical study. Research is done in an iterative process of hypothesis and verification, including several steps of modeling, computer simulation and experimental measurements.
See also[edit]
References[edit]
![Biomechanical device implant in spine Biomechanical device implant in spine](https://chiro.org/ACAPress/GRAPHICS_2/SPINAL_BIOMECHANICS/General_Spinal_Biomechanics_Fig_6_53.jpg)
- ^R. McNeill Alexander (2005) Mechanics of animal movement, Current Biology Volume 15, Issue 16, 23 August 2005, Pages R616-R619. doi:10.1016/j.cub.2005.08.016
- ^Hatze, Herbert (1974). 'The meaning of the term biomechanics'. Journal of Biomechanics. 7 (12): 189–190. doi:10.1016/0021-9290(74)90060-8.
- ^Oxford English Dictionary, Third Edition, November 2010, s.vv.
- ^Aboelkassem, Yasser (2013). 'Selective pumping in a network: insect-style microscale flow transport'. Bioinspiration & Biomimetics. 8 (2): 026004. Bibcode:2013BiBi....8b6004A. doi:10.1088/1748-3182/8/2/026004. PMID23538838.
- ^Davim, J. Paulo (2013). Biotribology. John Wiley & Sons. ISBN978-1-118-61705-2.
- ^ abcWhitney, G. A., Jayaraman, K., Dennis, J. E. and Mansour, J. M. (2014), Scaffold-free cartilage subjected to frictional shear stress demonstrates damage by cracking and surface peeling. J Tissue Eng Regen Med. doi: 10.1002/term.1925
- ^ abBidhendi, Amir J; Geitmann, Anja (January 2018). 'Finite element modeling of shape changes in plant cells'(PDF). Plant Physiology. 176 (1): 41–56. doi:10.1104/pp.17.01684. PMC5761827. PMID29229695.
- ^Tsouknidas, A., Savvakis, S., Asaniotis, Y., Anagnostidis, K., Lontos, A., Michailidis, N. (2013) The effect of kyphoplasty parameters on the dynamic load transfer within the lumbar spine considering the response of a bio-realistic spine segment. Clinical Biomechanics 28 (9–10), pp. 949–955.
- ^ abFung 1993
- ^Niklas, Karl J. (1992). Plant Biomechanics: An Engineering Approach to Plant Form and Function (1 ed.). New York, NY: University Of Chicago Press. p. 622. ISBN978-0-226-58631-1.
- ^Forell, G. V., Robertson, D., Lee, S. Y., Cook, D. D. (2015), Preventing lodging in bioenergy crops: a biomechanical analysis of maize stalks suggests a new approach. J Exp Bot. doi: 10.1093/jxb/erv108
- ^Bartlett, Roger (1997). Introduction to sports biomechanics (1 ed.). New York, NY: Routledge. p. 304. ISBN978-0-419-20840-2.
- ^Michael Yessis (2008). Secrets of Russian Sports Fitness & Training. ISBN978-0-9817180-2-6.
- ^Abernethy, Bruce; Vaughan Kippers; Stephanie J. Hanrahan; Marcus G. Pandy; Alison M. McManus; Laurel MacKinnon (2013). Biophysical foundations of human movement (3rd ed.). Champaign, IL: Human Kinetics. p. 84. ISBN978-1-4504-3165-1.
- ^Martin, R. Bruce (23 October 1999). 'A genealogy of biomechanics'. Presidential Lecture presented at the 23rd Annual Conference of the American Society of Biomechanics University of Pittsburgh, Pittsburgh PA. Archived from the original on 8 August 2013. Retrieved 2 January 2014.
- ^ abcde'American Society of Biomechanics » The Original Biomechanists'. www.asbweb.org. Retrieved 25 October 2017.
- ^ abMason, Stephen (1962). A History of the Sciences. New York, NY: Collier Books. p. 550.
- ^Humphrey, Jay D. (2003). The Royal Society (ed.). 'Continuum biomechanics of soft biological tissues'(PDF). Proceedings of the Royal Society of London A. 459 (2029): 3–46. Bibcode:2003RSPSA.459....3H. doi:10.1098/rspa.2002.1060.
- ^R. Bruce Martin (23 October 1999). 'A Genealogy of Biomechanics'. 23rd Annual Conference of the American Society of Biomechanics. Archived from the original on 17 September 2010. Retrieved 13 October 2010.
- ^Nia, H.T.; et al. (2017). 'Solid stress and elastic energy as measures of tumour mechanopathology'. Nature Biomedical Engineering. 004: 0004. doi:10.1038/s41551-016-0004. PMC5621647. PMID28966873.
- ^Basmajian, J.V, & DeLuca, C.J. (1985) Muscles Alive: Their Functions Revealed, Fifth edition. Williams & Wilkins.
- ^Holzapfel, Gerhard A.; Ogden, Ray W. (2009). Biomechanical Modelling at the Molecular, Cellular and Tissue Levels. Springer Science & Business Media. p. 75. ISBN978-3-211-95875-9.
Further reading[edit]
- Cowin, Stephen C., ed. (2008). Bone mechanics handbook (2nd ed.). New York: Informa Healthcare. ISBN978-0-8493-9117-0.
- Fischer-Cripps, Anthony C. (2007). Introduction to contact mechanics (2nd ed.). New York: Springer. ISBN978-0-387-68187-0.
- Fung, Y.-C. (1993). Biomechanics: Mechanical Properties of Living Tissues. New York: Springer-Verlag. ISBN978-0-387-97947-2.
- Gurtin, Morton E. (1995). An introduction to continuum mechanics (6 ed.). San Diego: Acad. Press. ISBN978-0-12-309750-7.
- Humphrey, Jay D. (2002). Cardiovascular solid mechanics : cells, tissues, and organs. New York: Springer. ISBN978-0-387-95168-3.
- Mazumdar, Jagan N. (1993). Biofluids mechanics (Reprint 1998. ed.). Singapore: World Scientific. ISBN978-981-02-0927-8.
- Mow, Van C.; Huiskes, Rik, eds. (2005). Basic orthopaedic biomechanics & mechano-biology (3 ed.). Philadelphia: Lippincott, Williams & Wilkins. p. 2. ISBN978-0-7817-3933-7.
- Peterson, Donald R.; Bronzino, Joseph D., eds. (2008). Biomechanics : principles and applications (2. rev. ed.). Boca Raton: CRC Press. ISBN978-0-8493-8534-6.
- Temenoff, J.S.; Mikos, A.G. (2008). Biomaterials : the Intersection of biology and materials science (Internat. ed.). Upper Saddle River, N.J.: Pearson/Prentice Hall. ISBN978-0-13-009710-1.
- Totten, George E.; Liang, Hong, eds. (2004). Mechanical tribology : materials, characterization, and applications. New York: Marcel Dekker. ISBN978-0-8247-4873-9.
- Waite, Lee; Fine, Jerry (2007). Applied biofluid mechanics. New York: McGraw-Hill. ISBN978-0-07-147217-3.
- Young, Donald F.; Bruce R. Munson; Theodore H. Okiishi (2004). A brief introduction to fluid mechanics (3rd ed.). Hoboken, N.J.: Wiley. ISBN978-0-471-45757-2.