Repair of a Radial Fracture with Radial Head Luxation in a Bugio Monkey (Alouatta caraya)

Bugio monkeys (Alouatta caraya) need their arms for locomotion, hygiene, and defence, and possess well-developed dexterity of their hands, depending on them for proper feeding. For this reason, appropriate treatment of thoracic limb fractures is not only essential but also challenging in this species. This report describes the successful treatment of a radial fracture associated with luxation of the radial head in a female, adult Alouatta caraya. The patient was admitted after a suspected traumatic event with a complete transverse fracture of the right radial diaphysis and subluxation of the ipsilateral radius head. Using a craniomedial approach to the radius, surgical stabilization was performed using a 1.7 mm micro series Fixin locking plate after open reduction in bone fragments. The patient had early use of the limb (24 hours postoperatively) and progressive improvement in its usual activities over the following weeks. Radiographic monitoring was performed at 30, 60, and 360 days postoperatively, and bone healing occurred with no complications. The treatment of fractures in primates is potentially challenging, requiring adaptation to primate anatomy and the specific living conditions of the species. Open reduction and stabilization of the radial fracture with a plate and manually reducing the luxated radial head effectively lead to long-term restoration of full function and of normal activities.

PRIMATE ANATOMY, KINEMATICS, AND PRINCIPLES FOR HUMANOID DESIGN

The primate order of animals is investigated for clues in the design of humanoid robots. The pursuit is directed with a theory that kinematics, musculature, perception, and cognition can be optimized for specific tasks by varying the proportions of limbs, and in particular, the points of branching in kinematic trees such as the primate skeleton. Called the Bifurcated Chain Hypothesis, the theory is that the branching proportions found in humans may be superior to other animals and primates for the tasks of dexterous manipulation and other human specialties. The primate taxa are defined, contemporary primate evolution hypotheses are critiqued, and variations within the order are noted. The kinematic branching points of the torso, limbs and fingers are studied for differences in proportions across the order, and associated with family and genus capabilities and behaviors. The human configuration of a long waist, long neck, and short arms is graded using a kinematic workspace analysis and a set of design axioms for mobile manipulation robots. It scores well. The re-emergence of the human waist, seen in early prosimians and monkeys for arboreal balance, but lost in the terrestrial pongidae, is postulated as benefiting human dexterity. The human combination of an articulated waist and neck will be shown to enable the use of smaller arms, achieving greater regions of workspace dexterity than the larger limbs of gorillas and other hominoidea.