Hamrick 9603808 Modeling refers to the process of cartilage and bone formation and resorption during growth. Theoretical models predict that mechanical factors such as joint movement and loading guide the modeling of mammalian limb joints. This study seeks to test these theoretical predictions directly by investigating the influence of changing body size, muscle morphology, and locomotor behavior on marsupial limb joint shape during growth and development. These empirical data are called for to address the following outstanding questions concerning limb joint structure and function. For example, how is limb joint design modified in relation to increasing organismal size? What changes in joint morphology are evident following the onset of independent locomotor behavior? How do joint surfaces adapt to morphological changes in the muscles acting on them during growth? Finally, are certain aspects of joint shape more labile and others more invariant during the modeling process? The proposed study will provide a much needed developmental perspective on limb joint structure and function by identifying those aspects of joint morphology which are highly canalized during growth and those which are instead more variable under different mechanical conditions. These data have clinical relevance for understanding the developmental basis of joint malformations in humans, and more general biological significance for understanding the factors underlying both within- and between-species variation in mammalian limb joint form.
