Metatarsal robusticity in bipedal rats

Abstract

All metatarsals have a significantly greater robusticity i n the male than in the female rat. The robusticity formula of the rat's foot is 1 > 5 > 2 > 3 > 4. In bipedal rats that formula remains unchanged, but the robusticity of the metatarsals is increased especially in females. The tripod arrangement of the human foot with its particular robustness of the marginal metatarsals 1 and 5 and a strong calcaneum has been related to upright posture. The similar robusticity pattern in the rat's marginal metatarsals 1 and 5 raises the question of whether that part of the formula might not represent a more general plantigrade pattern.In a paper dealing with fossil foot bones, Day and Napier ('64) have demonstrated that the robusticity of the metatarsals is a n important indicator of weight distribution through the foot. Defining the robusticity index as the mid-shaft diameter times one hundred over the length, the authors have shown that in modern man and in the Olduvai foot, the fifth metatarsal is the second most robust after the first while in the lowland and mountain gorilla, it is the least robust. However, the third metatarsal of the Olduvai foot has a greater robusticity than the fourth, while in modern m a n that order is reversed. Thus, the robusticity formula for modern man is: 1 > 5 > 4 > 3 > 2 while for Olduvai it is 1 > 5 > 3 > 4 > 2; and for the two gorillas it is: 1 > 2 > 3 > 4 > 5. From this the authors conclude that the particular robustness of the marginal metatarsals and a stout calcaneum, are the skeletal adaptations of the foot to upright stance and fully bipedal gait i n modern man, and that 01-duvai man possessed the basic structural requirements for it as well. Campbell ('66) has compared this arrangement of the human foot bones to the stable character of a tripod.In the present study an attempt was made to (1) establish the formula of metatarsal robusticity for a relatively unspecialized plantigrade animal such as the rat; ( 2 ) determine whether there exists a AM. J. PHYS. ANTHROP.. 36. 22S234.sexual dimorphism of metatarsal robusticity; and ( 3 ) determine whether the robusticity of the metatarsals could be altered experimentally by increasing the weight-bearing load in the foot of bipedal rats. MATERIAL AND METHODSIt is customary to establish the index of robusticity of a long bone by relating its width, as measured at the mid-point of its shaft, to its total length. However, such a n index was considered unsatisfactory in the rat for the following reasons: (1) a mid-point on the shaft can be established with sufficient accuracy on a relatively large bone but is difficult to establish on the small metatarsals of the rat's foot; ( 2 ) such a mid-point is a n arbitrary geometrical point with no special physiological or biomechanical significance; ( 3 ) a diameter at that point expresses only a single spatial dimension instead of the complete spatial quality of the bone as a whole. Total length was therefore related to the cubic root of the weight. Such a ponderal index, customary in som...

Potential of oak acorn with and without polyethylene glycol as an alternative to corn in broiler diets

“…The effects of OA level and PEG on tibia characteristics at 21 and 42 days of age (Table 7) showed that birds given 150 and 200 g/kg OA had lower tibia weight and length compared with those given diets (Rao et al, 1993). The robusticity index and bone ash weight / bone length index (Reisenfeld, 1972;Seedor et al, 1991) are also important. Based on these parameters, feeding with 200 g/kg OA impaired tibia bone status, which was reflected in the lower bone ash weight / bone length index on days 21 and 42, as well as lower ash on day 42.…”

“…The tibia bone ash weight / tibia bone length index was calculated by dividing the tibia ash weight by its length (Seedor et al, 1991). The tibia robusticity index was calculated with this formula: tibia length / cube root of tibia weight (Reisenfeld, 1972). The calcium and phosphorus contents of the tibia bones were determined by flame atomic absorption spectrophotometry and molybdo-vanadate methods, respectively (AOAC, 1995).…”

Bone Morphometric Parameters of the Tibia and Femur of Indigenous and Broiler Chickens Reared Intensively

“…Medullary canal diameter was calculated by subtracting the thicknesses of the medial and lateral walls from the diameter at the diaphysis while bone weight/length index also known as the Seedor index was obtained by dividing the tibia weight by its length (Seedor et al, 1991). The tibiotarsal and the robusticity indexes were determined using the following formulas (Reisenfeld, 1972), respectively:…”

Dietary nutrient manipulation to improve the performance and tibia characteristics of broilers fed oak acorn (Quercus Brantii Lindl)

“…Tibia ash weight/tibia bone length index was calculated by dividing the tibia ash weight by its length (Seedor et al, 1991). Tibia robusticity index was calculated using following formula: Robusticity index = tibia length/cube root of tibia weight (Reisenfeld, 1972).…”