RESUMEN
Full thumb mobility is required to execute tasks of daily living and results from the combined motions of the thumb joints. In this study, we focus on the coupling between the proximal joints of the thumb, the radioscaphoid (RS), scaphotrapezial (ST) and trapeziometacarpal (TMC) joints. We quantified the 3D kinematics of these joints during maximal thumb extension and abduction in a group of healthy volunteers using an image-based technique. Semi-dynamic CT scans of the dominant hand of 36 healthy subjects with the thumb in different standardized positions were used. The maximal range of motion of each joint in the different planes was calculated using a markerless bone registration method. Inter-joint coupling was assessed by performing a regression analysis between the range of motion of the joints during both thumb movements. Strong inter-joint coupling was found between the RS and ST joints during thumb extension and abduction, whereas coupling between the other joints was moderate to weak. This study provides valuable information on the in vivo 3D kinematics of the RS, ST and TMC joints during thumb movement. This can be used as input for modeling studies, where the coupling between the joints can decrease the degrees of freedom of the model. Moreover, these baseline data of a healthy cohort can be used for comparison with the kinematics of patients with TMC osteoarthritis or other pathologies and aid our understanding of motion deficits resulting from these joint disorders.
Asunto(s)
Articulaciones Carpometacarpianas , Osteoartritis , Fenómenos Biomecánicos , Articulaciones Carpometacarpianas/diagnóstico por imagen , Humanos , Movimiento , Rango del Movimiento Articular , Pulgar/diagnóstico por imagenRESUMEN
Chimpanzees are knuckle walkers, with forelimbs contacting the ground by the dorsum of the finger's middle phalanges. As these muscular apes are given to high-velocity motions, the question arises of how the ground reaction forces are buffered so that no damage ensues in the load-bearing fingers. In the literature, it was hypothesized that the finger flexors help buffer impacts because in knuckle stance the metacarpophalangeal joints (MCPJs) are strongly hyperextended, which would elongate the finger flexors. This stretching of the finger flexor muscle-tendon units would absorb impact energy. However, EMG studies did not report significant finger flexor activity in knuckle walking. Although these data by themselves question the finger flexor impact buffering hypothesis, the present study aimed to critically investigate the hypothesis from a biomechanical point of view. Therefore, various aspects of knuckle walking were modeled and the finger flexor tendon displacements in the load-bearing fingers were measured in a chimpanzee cadaver hand, of which also an MRI was taken in knuckle stance. The biomechanics do not support the finger flexor impact buffering hypothesis. In knuckle walking, the finger flexors are not elongated to lengths where passive strain forces would become important. Impact buffering by large flexion moments at the MCPJs from active finger flexors would result in impacts at the knuckles themselves, which is dysfunctional for various biomechanical reasons and does not occur in real knuckle walking. In conclusion, the current biomechanical analysis in accumulation of previous EMG findings suggests that finger flexors play no role in impact buffering in knuckle walking.
Asunto(s)
Hominidae , Pan troglodytes , Animales , Fenómenos Biomecánicos , Articulación Metacarpofalángica , CaminataRESUMEN
Current motion capture techniques all have shortcomings when applied to the 3D quantitative evaluation of thumb base motion. Dynamic CT might overcome these shortcomings but, so far, robustness of this technique in more than one specimen has not yet been demonstrated. The aim of the current study is to further evaluate the use of dynamic CT for quantification of thumb motion in a larger cadaveric study using a protocol which is feasible in a clinical context. A dynamic CT scan was acquired from six cadaveric human forearms, while a motion simulator imposed thumb opposition. After image acquisition and segmentation, carpal bone motion was quantified using helical axes. To enable comparisons between specimens, intersection points of the instantaneous helical axis with an anatomically defined plane were determined. Precision of the dynamic CT method, measured as variation in distances between silicon nitride beads between frames of a dynamic scan, was 0.43mm (+/-0.09mm) when fixed to the skin and 0.13mm (+/-0.04mm) when embedded into the bone. Absolute deviation between known and measured distances were not larger than 0.34mm. We could demonstrate and quantify that thumb opposition is associated with motion at the trapeziometacarpal and scaphotrapezotrapezoidal joints. High consistency in motion patterns between specimen were found, while the radiation dose was limited. We conclude that dynamic CT can be used to visualize and quantify 3D thumb kinematics, making it a promising method to explore kinematics in vivo.
Asunto(s)
Pulgar/fisiología , Fenómenos Biomecánicos , Huesos del Carpo/diagnóstico por imagen , Huesos del Carpo/fisiología , Humanos , Movimiento/fisiología , Pulgar/diagnóstico por imagen , Tomografía Computarizada por Rayos XRESUMEN
PURPOSE: The respective roles of the dorsoradial (DRL) and anterior oblique (AOL) ligaments in stability of the highly mobile trapeziometacarpal (TMC) joint remain disputed. Earlier publications have pointed to the AOL as the key stabilizing structure; yet, more recent publications have challenged the stabilizing role of the AOL, favoring the DRL as the main TMC joint stabilizer. We executed an anatomical study of the ligaments, including detailed dissection to quantify the length, width, and thickness of the AOL and DRL and tested the material properties of these ligaments. METHODS: Thirteen fresh frozen cadaveric thumbs from 9 specimens were used. Length, width, and thickness of the AOL and DRL were measured on magnetic resonance imaging and/or after dissection. Next, the first metacarpal and trapezium were isolated together with both ligaments, and both bones were cut sagittally to isolate a first metacarpal-AOL-trapezium and first metacarpal-DRL-trapezium complex from each thumb. These samples were subjected to cyclic loading in displacement-controlled tests. The obtained force-displacement curves were used to calculate stiffness and hysteresis of each sample. RESULTS: Our results showed that the DRL is significantly shorter and thicker than the AOL, which is thin and ill-defined. Our results also indicate that the DRL has a higher stiffness than the AOL, making it a more likely candidate to provide joint stability. CONCLUSIONS: Although the AOL has been asserted to be the primary restraint to dorsoradial subluxation, this view has been challenged over the past 10 years by several studies. These studies have shown the AOL to be relatively weak and compliant compared with the intermetacarpal and dorsoradial ligaments and have demonstrated that the DRL is the strongest and stiffest ligament of the TMC joint. Our studies confirm these findings. CLINICAL RELEVANCE: This study indicates that the DRL is relatively stiff and thick, suggesting it should be repaired or reconstructed when disrupted to restore stability of the TMC joint.
Asunto(s)
Articulaciones Carpometacarpianas/anatomía & histología , Articulaciones Carpometacarpianas/fisiología , Ligamentos Articulares/anatomía & histología , Ligamentos Articulares/fisiología , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Cadáver , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Metacarpo/anatomía & histología , Metacarpo/fisiología , Persona de Mediana Edad , Articulación de la Muñeca/anatomía & histología , Articulación de la Muñeca/fisiologíaRESUMEN
The axial musculoskeletal system is important for the static and dynamic control of the body during both locomotor and non-locomotor behaviour. As a consequence, major evolutionary changes in the positional habits of a species are reflected by morpho-functional adaptations of the axial system. Because of the remarkable phenotypic plasticity of muscle tissue, a close relationship exists between muscle morphology and function. One way to explore major evolutionary transitions in muscle function is therefore by comparative analysis of fibre type composition. In this study, the three-dimensional distribution of slow and fast muscle fibres was analysed in the lumbar perivertebral muscles of two lemuriform (mouse lemur, brown lemur) and four hominoid primate species (white-handed gibbon, orangutan, bonobo, chimpanzee) in order to develop a plausible scenario for the evolution of the contractile properties of the axial muscles in hominoids and to discern possible changes in muscle physiology that were associated with the evolution of orthogrady. Similar to all previously studied quadrupedal mammals, the lemuriform primates in this study exhibited a morpho-functional dichotomy between deep slow contracting local stabilizer muscles and superficial fast contracting global mobilizers and stabilizers and thus retained the fibre distribution pattern typical for quadrupedal non-primates. In contrast, the hominoid primates showed no regionalization of the fibre types, similar to previous observations in Homo. We suggest that this homogeneous fibre composition is associated with the high functional versatility of the axial musculature that was brought about by the evolution of orthograde behaviours and reflects the broad range of mechanical demands acting on the trunk in orthograde hominoids. Because orthogrady is a derived character of euhominoids, the uniform fibre type distribution is hypothesized to coincide with the evolution of orthograde behaviours.
Asunto(s)
Hominidae/anatomía & histología , Fibras Musculares Esqueléticas/citología , Músculos Paraespinales/anatomía & histología , Músculos Paraespinales/citología , Anatomía Comparada , Animales , Evolución Biológica , Femenino , Hylobates , Inmunohistoquímica , Lemur , Vértebras Lumbares , Región Lumbosacra , Pan troglodytes , Pongo , Primates , Especificidad de la EspecieRESUMEN
Gibbons are skilled brachiators but they are also highly capable leapers, crossing distances in excess of 10 m in the wild. Despite this impressive performance capability, no detailed biomechanical studies of leaping in gibbons have been undertaken to date. We measured ground reaction forces and derived kinematic parameters from high-speed videos during gibbon leaps in a captive zoo environment. We identified four distinct leap types defined by the number of feet used during take-off and the orientation of the trunk, orthograde single-footed, orthograde two-footed, orthograde squat, and pronograde single-footed leaps. The center of mass trajectories of three of the four leap types were broadly similar, with the pronograde single-footed leaps exhibiting less vertical displacement of the center of mass than the other three types. Mechanical energy at take-off was similar in all four leap types. The ratio of kinetic energy to mechanical energy was highest in pronograde single-footed leaps and similar in the other three leap types. The highest mechanical work and power were generated during orthograde squat leaps. Take-off angle decreased with take-off velocity and the hind limbs showed a proximal to distal extension sequence during take-off. In the forelimbs, the shoulder joints were always flexed at take-off, while the kinematics of the distal joints (elbow and wrist joints) were variable between leaps. It is possible that gibbons may utilize more metabolically expensive orthograde squat leaps when a safe landing is uncertain, while more rapid (less expensive) pronograde single-footed leaps might be used during bouts of rapid locomotion when a safe landing is more certain.
Asunto(s)
Hylobates/anatomía & histología , Hylobates/fisiología , Locomoción/fisiología , Análisis de Varianza , Animales , Fenómenos Biomecánicos , Femenino , Articulaciones/anatomía & histología , Articulaciones/fisiología , Modelos Lineales , Grabación en VideoRESUMEN
Based on our knowledge of locomotor biomechanics and ecology we predict the locomotion and posture of the last common ancestors of (a) great and lesser apes and their close fossil relatives (hominoids); (b) chimpanzees, bonobos and modern humans (hominines); and (c) modern humans and their fossil relatives (hominins). We evaluate our propositions against the fossil record in the context of a broader review of evolution of the locomotor system from the earliest hominoids of modern aspect (crown hominoids) to early modern Homo sapiens. While some early East African stem hominoids were pronograde, it appears that the adaptations which best characterize the crown hominoids are orthogrady and an ability to abduct the arm above the shoulder - rather than, as is often thought, manual suspension sensu stricto. At 7-9 Ma (not much earlier than the likely 4-8 Ma divergence date for panins and hominins, see Bradley, 2008) there were crown hominoids in southern Europe which were adapted to moving in an orthograde posture, supported primarily on the hindlimb, in an arboreal, and possibly for Oreopithecus, a terrestrial context. By 7 Ma, Sahelanthropus provides evidence of a Central African hominin, panin or possibly gorilline adapted to orthogrady, and both orthogrady and habitually highly extended postures of the hip are evident in the arboreal East African protohominin Orrorin at 6 Ma. If the traditional idea that hominins passed through a terrestrial 'knuckle-walking' phase is correct, not only does it have to be explained how a quadrupedal gait typified by flexed postures of the hindlimb could have preadapted the body for the hominin acquisition of straight-legged erect bipedality, but we would have to accept a transition from stem-hominoid pronogrady to crown hominoid orthogrady, back again to pronogrady in the African apes and then back to orthogrady in hominins. Hand-assisted arboreal bipedality, which is part of a continuum of orthograde behaviours, is used by modern orangutans to forage among the small branches at the periphery of trees where the core hominoid dietary resource, ripe fruit, is most often to be found. Derivation of habitual terrestrial bipedality from arboreal hand-assisted bipedality requires fewer transitions, and is also kinematically and kinetically more parsimonious.
Asunto(s)
Evolución Biológica , Hominidae/fisiología , Locomoción/fisiología , Adaptación Fisiológica , Animales , Antropología Física , Fenómenos Biomecánicos , Fósiles , Hominidae/anatomía & histología , Humanos , Estilo de Vida , PosturaRESUMEN
Flexion/extension moment arms were obtained for the major muscles crossing the hip, knee and ankle joints in the orang-utan, gibbon, gorilla (Eastern and Western lowland) and bonobo. Moment arms varied with joint motion and were generally longer in proximal limb muscles than distal limb muscles. The shape of the moment arm curves (i.e. the plots of moment arm against joint angle) differed in different hindlimb muscles and in the same muscle in different subjects (both in the same and in different ape species). Most moment arms increased with increasing joint flexion, a finding which may be understood in the context of the employment of flexed postures by most non-human apes (except orang-utans) during both terrestrial and arboreal locomotion. When compared with humans, non-human great apes tended to have muscles better designed for moving the joints through large ranges. This was particularly true of the pedal digital flexors in orang-utans. In gibbons, the only lesser ape studied here, many of the moment arms measured were relatively short compared with those of great apes. This study was performed on a small sample of apes and thus differences noted here warrant further investigation in larger populations.
Asunto(s)
Miembro Posterior/anatomía & histología , Miembro Posterior/fisiología , Locomoción/fisiología , Primates/fisiología , Animales , Fenómenos Biomecánicos , Gorilla gorilla/anatomía & histología , Gorilla gorilla/fisiología , Humanos , Hylobates/anatomía & histología , Hylobates/fisiología , Músculo Esquelético/anatomía & histología , Músculo Esquelético/fisiología , Pan paniscus/anatomía & histología , Pan paniscus/fisiología , Pongo pygmaeus/anatomía & histología , Pongo pygmaeus/fisiología , PosturaRESUMEN
We present quantitative data on the hindlimb musculature of Pan paniscus, Gorilla gorilla gorilla, Gorilla gorilla graueri, Pongo pygmaeus abelii and Hylobates lar and discuss the findings in relation to the locomotor habits of each. Muscle mass and fascicle length data were obtained for all major hindlimb muscles. Physiological cross-sectional area (PCSA) was estimated. Data were normalized assuming geometric similarity to allow for comparison of animals of different size/species. Muscle mass scaled closely to (body mass)(1.0) and fascicle length scaled closely to (body mass)(0.3) in most species. However, human hindlimb muscles were heavy and had short fascicles per unit body mass when compared with non-human apes. Gibbon hindlimb anatomy shared some features with human hindlimbs that were not observed in the non-human great apes: limb circumferences tapered from proximal-to-distal, fascicle lengths were short per unit body mass and tendons were relatively long. Non-human great ape hindlimb muscles were, by contrast, characterized by long fascicles arranged in parallel, with little/no tendon of insertion. Such an arrangement of muscle architecture would be useful for locomotion in a three dimensionally complex arboreal environment.