bone modelling


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modelling

Physiology
The process of bone formation by osteoblasts and osteoclastic resorption, which ends with bone maturation.
 
Psychology
A normal process of personality development, in which a child learns appropriate social and cognitive behaviours by imitating a socially accepted significant other (the model); these behaviours are positively reinforced and eventually integrated into the child’s personality profile.

Research
The simulation of an experiment based on hypothetical conditions, considered by some to be a “third form of science” (in addition to theory and experimentation). Modelling is used in neural networks, molecular dynamics, cell membrane interactions and in biosphere analysis. It allows examination of a problem and testing of highly complex hypothetical solutions thereto, performing only experiments with a high probability of success (based on predictions).
 
Suicidology
Suicidal behaviour or completion in response of a person close to the suicide completer.

Theoretical medicine
The use of mathematical models to simulate environmental movements of radionuclides and chemicals released from a radioactive facility’s stacks, and how these materials disperse as they move with the wind, deposit on crops, are inhaled or ingested, and to determine the resulting doses. Some models are complex, requiring information such as weather conditions, crops, eating habits, etc.; others are relatively simple.

bone modelling

reaction of developing bone (i.e. cartilaginous precursor, metaphyses, epiphyses and articular surfaces) to imposed forces (e.g. decreased or increased density) ensuring optimum strain response and lightness (Table 1)
Table 1: Bone modelling
Type of modellingComment
Chondral modelling during bone growthRate of ossification of cartilaginous precursor of bone/articular cartilage/epiphyseal plates depends on imposed load during development
Joint incongruence within normal range: load inequality across articular cartilage causes remodelling and restoration of maximal congruence, via negative-feedback loop
Joint incongruence beyond normal range: load inequality across articular cartilage causes remodelling adapting to abnormal load, and loss of maximal congruence, via positive-feedback loop
Metaphyses and epiphysesWhere abduction and adduction forces about a joint (e.g. knee) are equal, resultant transverse force across the joint is of zero magnitude
Where adductor force > abductor force:
• Soft-tissue anomaly causes soft-tissue positional genu valgum and increases force on lateral articular surface/epiphyseal areas
• Rate of bone growth at lateral areas increases; that of medial areas remains normal
• Joint congruence is restored, and the horizontal force is restored to zero magnitude, but soft-tissue genu valgum deformity persists as bone deformity
Articular surfacesMinor incongruence between articular surfaces within a synovial joint causes large changes in forces acting at different parts of articular surface, e.g.
• Absent subtalar joint inversion/eversion causes trochlear talus to undergo reactive twist within ankle mortise, and compression at articular areas remaining in contact
• Excess loading at these sites reduces local bone growth; unloaded areas continue to grow at normal rate
• Shape of articular surface gradually changes, adapting to abnormal loading pattern, and maximum congruence is achieved, but trochlea becomes rounded (rather than pulley-shaped) and ankle joint forms ball-and-socket, rather than hinge, joint
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