Free-ranging Cayo Santiago rhesus monkeys (Macaca mulatta): II. Passive joint mobility.

Recent studies on the effects of caging on joint mobility and the correlations between joint mobility and use of the extremities have pointed out the need for baseline values that are readily available in the literature. This report provides normative data on the passive mobility of the major joints of free-ranging Cayo Santiago rhesus monkeys (Macaca mulatta). The sample in this cross-sectional study is large (661 animals including 315 males, 346 females), and it spans the entire age spectrum (24 hours to 25 years) of the population. Included are data on motion in the sagittal plane at six joints: shoulder, elbow, wrist, hip, knee, and ankle. Results indicated that passive joint mobility changes in a nonlinear fashion throughout the life cycle. The apparent rapid decline in mobility from birth through puberty parallels rapid changes in body size and proportions in young animals. Joint mobility is relatively stable in prime-age adults, whereas it is generally more restricted in older monkeys. Both genders follow a similar pattern, but timing differs somewhat. Although the primary purpose of this paper is to present numerical data on the Cayo Santiago population, the results are compared with previous, more limited studies of both captive and free-ranging rhesus macaques.