Article

Impact-absorbing properties of the human knee.

Queen's Medical Centre, Nottingham, England.
The Bone & Joint Journal (Impact Factor: 2.8). 12/1987; 69(5):807-11.
Source: PubMed

ABSTRACT A biomechanical study has been carried out on 20 cadaveric knees to investigate their load-absorbing mechanism. The impact load was applied using a weight falling onto the transected proximal femur and the force transmitted through the knee was measured at the transected distal tibia using a load transducer. The peak force transmitted increased as, sequentially, meniscus, articular cartilage and subchondral bone were damaged or removed. The most striking result was found in an implanted knee replacement where the transmitted force reached 180% of that in the intact knee. The results show that the joint has an impact-absorbing property in each segment and that in the osteoarthritic knee there is less absorption of shock than in the normal knee. The high impact force in an implanted knee suggests that microfractures of the cancellous bone might be expected and may produce loosening.

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    • "Subchondral bone is the thin layer of cortical bone immediately deep to the articular cartilage in synovial joints. Subchondral bone serves to transmit and distribute forces from the joint surface to the underlying trabecular bone, and it may serve to dissipate a small portion of the force as well (Hoshino and Wallace 1987; Radin and Paul 1971; Radin et al. 1970; Simon et al. 1972). "
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    ABSTRACT: We analyze patterns of subchondral bone apparent density in the distal femur of extant primates to reconstruct differences in knee posture, discriminate among extant species with different locomotor preferences, and investigate the knee postures used by subfossil lemur species Hadropithecus stenognathus and Pachylemur insignis. We obtained computed tomographic scans for 164 femora belonging to 39 primate species. We grouped species by locomotor preference into knuckle-walking, arboreal quadruped, terrestrial quadruped, quadrupedal leaper, suspensory and vertical clinging, and leaping categories. We reconstructed knee posture using an experimentally validated procedure of determining the anterior extent of the region of maximal subchondral bone apparent density on a median slice through the medial femoral condyle. We compared subchondral apparent density magnitudes between subfossil and extant specimens to ensure that fossils did not display substantial mineralization or degradation. Subfossil and extant specimens were found to have similar magnitudes of subchondral apparent density, thereby permitting comparisons of the density patterns. We observed significant differences in the position of maximum subchondral apparent density between leaping and nonleaping extant primates, with leaping primates appearing to use much more flexed knee postures than nonleaping species. The anterior placement of the regions of maximum subchondral bone apparent density in the subfossil specimens of Hadropithecus and Pachylemur suggests that both species differed from leaping primates and included in their broad range of knee postures rather extended postures. For Hadropithecus, this result is consistent with other evidence for terrestrial locomotion. Pachylemur, reconstructed on the basis of other evidence as a committed arboreal quadruped, likely employed extended knee postures in other activities such as hindlimb suspension, in addition to occasional terrestrial locomotion.
    International Journal of Primatology 04/2010; 31(2):275-299. DOI:10.1007/s10764-010-9401-y · 1.99 Impact Factor
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    • "Subchondral bone, located between the articular cartilage and trabecular bone, serves to transmit and distribute forces from the joint surface to the trabecular bone, and it may attenuate some of the forces as well (Radin et al., 1970; Radin and Paul, 1971; Simon et al., 1972; Hoshino and Wallace, 1987). Changes in the apparent density of subchondral bone have been observed in many comparative studies (see below) and increased density may provide several biomechanical advantages. "
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    ABSTRACT: Body mass has been shown in experimental and comparative morphological studies to have a significant effect on joint posture in major limb joints. The generalizability of experimental studies is limited by their use of small sample sizes and limited size ranges. In contrast, while comparative morphological studies often have increased sample sizes, the connection between joint posture and morphological variables is often indirect. The current study infers joint postures for a large sample of primates using an experimentally validated method, and tests whether larger primates use more extended joint postures than smaller species. Postures are inferred through the analysis of patterns of subchondral bone apparent density on the medial femoral condyle. Femora from 94 adult wild-shot individuals of 28 species were included. Apparent density measurements were obtained from CT scans using AMIRA software, and the angular position of the anterior-most extent of the region of maximum apparent density on the medial femoral condyle was recorded. In general, the hypothesis that larger-bodied primates use more extended knee posture was supported, but it should be noted that considerable variation exists, particularly at small body sizes. This indicates that smaller species are less constrained by their body size, and their patterns of apparent density are consistent with a wide range of knee postures. The size-related increase in inferred joint posture was observed in most major groups of primates, and this observation attests to the generalizability of Biewener's model that relates body size and joint posture.
    American Journal of Physical Anthropology 10/2009; 140(2):359-67. DOI:10.1002/ajpa.21083 · 2.51 Impact Factor
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    • "Subchondral bone is the thin plate of bone that is situated between the articular cartilage and trabecular bone. Because of its position at this interface, it may serve to transmit and distribute loads to the trabeculae and may also have some load attenuating function (Radin et al., 1970a; Radin and Paul, 1971; Simon et al., 1972; Hoshino and Wallace, 1987). The responses of subchondral bone to joint loading are not completely understood , but it appears to respond in a manner similar to other bony tissues (Radin and Paul, 1971; Simon et al., 1972; Eckstein et al., 1995; Murray et al., 2001; Burr and Radin, 2003), and while bone mineral density is largely influenced by heredity (Krall and Dawson- Hughes, 1993), other environmental factors such as exercise play significant roles (e.g., Forwood and Burr, 1993; Magkos et al., 2007). "
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    ABSTRACT: Spatial patterning in the apparent density of subchondral bone can be used to discriminate between species that differ in their joint loading conditions. This study provides an experimental test of two hypotheses that relate aspects of subchondral apparent density patterns to joint loading conditions. First, the region of maximum subchondral apparent density (RMD) will correspond to differences in joint posture at the time of peak locomotor loads; and second, differences in maximum density between individuals will correspond to differences in exercise level. These hypotheses were tested using three age-matched samples of juvenile sheep. Two groups of five sheep were exercised, at moderate walking speeds, twice daily for 45 days on a treadmill with either a 0% or 15% grade. The remaining sheep were not exercised. Sheep walking on the inclined treadmill used more flexed knee postures than those in the level walking group at the time of peak vertical ground reaction forces. Kinematic measurements of knee posture were compared with knee postures estimated from the spatial position of the RMD on the medial femoral condyle. Our results show that the difference in the position of the RMD between the incline and level walking groups corresponded to the difference in knee postures obtained kinematically; however, exercised and nonexercised sheep did not differ in the magnitude of apparent density. These results suggest that patterns of subchondral apparent density are good indicators of the experimental modifications in joint posture during locomotion and may, therefore, be used to investigate differences between species in habitual joint loading.
    The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 03/2008; 291(3):293-302. DOI:10.1002/ar.20653 · 1.53 Impact Factor

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