Inflammatory arthritis in Pongo

The character of parietal and orbital alterations in the superfamily Hominoidea (families Hominidae [exclusive of Homo] and Hylobotidae)

Parietal external surface disruption routinely referred to as porotic hyperostosis, and orbital alterations (cribra orbitalia), have been attributed to anemia-related bone marrow hyperplasia in humans. A recent study in humans identified that they were actually vascular in nature. Skeletons were examined and epi-illumination surface microscopy was performed on the parietal region and orbit of 156 Hominidae and 123 Hylobotidae to assess if these phenomena were trans-phylogenetic. Trans-cortical channels were recognized on the basis of visualized ectocranial surface defects penetrating the parietal; cribra orbitalia, by alteration of the normally smooth orbital roof appearance. Trans-cortical parietal channels, ranging in size from 20 to 100 µm, are rare in Gorilla and Pan troglodytes and absent in Pan paniscus. They are universally present in adult Pongo abeli and in Hylobatidae, independent of species. Cribra orbitalia was common in Hylobotidae, Pongo pygmaeus and P. abelii, less prevalent in adult P. troglodytes, and not recognized in any Gorilla gorilla or P. paniscus examined. The proliferative form predominated, with the exception of Hylobates concolor and muelleri, in which uncalcified vascular grooves predominated. No correlation was observed between the presence of either trans-cortical channels or cribra orbitalia and fractures, osteoarthritis, or inflammatory arthritis. Parietal alterations observed in apes are trans-cortical channels, analogous to those observed in humans, and do not represent porosity. Similarly, cribra orbitalia in apes is confirmed as vascular in nature. The proliferative form apparently represents calcification of blood vessel walls, indistinguishable from observations in humans. Predominant presence in adults rather than in juveniles suggests that both forms are acquired rather than developmental in derivation. Sex and bone alteration/disease-independence suggests that mechanical, endocrine, and inflammatory phenomena do not contribute to the development of either. Further, independent occurrence of trans-cortical channels and cribra orbitalia suggests that they do not have a shared etiology.

Comparative Pathology of Aging Great Apes: Bonobos, Chimpanzees, Gorillas, and Orangutans

The great apes (chimpanzees, bonobos, gorillas, and orangutans) are our closest relatives. Despite the many similarities, there are significant differences in aging among apes, including the human ape. Common to all are dental attrition, periodontitis, tooth loss, osteopenia, and arthritis, although gout is uniquely human and spondyloarthropathy is more prevalent in apes than humans. Humans are more prone to frailty, sarcopenia, osteoporosis, longevity past reproductive senescence, loss of brain volume, and Alzheimer dementia. Cerebral vascular disease occurs in both humans and apes. Cardiovascular disease mortality increases in aging humans and apes, but coronary atherosclerosis is the most significant type in humans. In captive apes, idiopathic myocardial fibrosis and cardiomyopathy predominate, with arteriosclerosis of intramural coronary arteries. Similar cardiac lesions are occasionally seen in wild apes. Vascular changes in heart and kidneys and aortic dissections in gorillas and bonobos suggest that hypertension may be involved in pathogenesis. Chronic kidney disease is common in elderly humans and some aging apes and is linked with cardiovascular disease in orangutans. Neoplasms common to aging humans and apes include uterine leiomyomas in chimpanzees, but other tumors of elderly humans, such as breast, prostate, lung, and colorectal cancers, are uncommon in apes. Among the apes, chimpanzees have been best studied in laboratory settings, and more comparative research is needed into the pathology of geriatric zoo-housed and wild apes. Increasing longevity of humans and apes makes understanding aging processes and diseases imperative for optimizing quality of life in all the ape species.

In vivo baseline measurements of hip joint range of motion in suspensory and nonsuspensory anthropoids

Hominoids and atelines are known to use suspensory behaviors and are assumed to possess greater hip joint mobility than nonsuspensory monkeys, particularly for range of abduction. This assumption has greatly influenced how extant and fossil primate hip joint morphology has been interpreted, despite the fact that there are no data available on hip mobility in hominoids or Ateles. This study uses in vivo measurements to test the hypothesis that suspensory anthropoids have significantly greater ranges of hip joint mobility than nonsuspensory anthropoids. Passive hip joint mobility was measured on a large sample of anesthetized captive anthropoids (nonhuman hominids = 43, hylobatids = 6, cercopithecids = 43, Ateles = 6, and Cebus = 6). Angular and linear data were collected using goniometers and tape measures. Range of motion (ROM) data were analyzed for significant differences by locomotor group using ANOVA and phylogenetic regression. The data demonstrate that suspensory anthropoids are capable of significantly greater hip abduction and external rotation. Degree of flexion and internal rotation were not larger in the suspensory primates, indicating that suspension is not associated with a global increase in hip mobility. Future work should consider the role of external rotation in abduction ability, how the physical position of the distal limb segments are influenced by differences in ROM proximally, as well as focus on bony and soft tissue differences that enable or restrict abduction and external rotation at the anthropoid hip joint.

Why are some species more commonly afflicted by arthritis than others? A comparative study of spondyloarthropathy in primates and carnivores

Spondyloarthropathy is a painful arthritic affliction of humans that also occurs in wild mammals. Important questions remain concerning the underlying causes of spondyloarthropathy in mammals, particularly regarding whether it is infectious in origin or driven by genetic predisposition and environmental stressors. Moreover, spondyloarthropathy has negative effects on host fitness, leading to potential conservation concerns if it impacts threatened species. Using a comparative data set on the prevalence of joint disease in 34 primate species and 100 carnivore species, we tested predictions involving the epidemiological correlates of spondyloarthropathy in wild mammals. Analyses revealed that 5.6% of primates and 3.6% of carnivores exhibited signs of spondyloarthropathy, with maximum incidence as high as 22% in great apes and 27% in bears. We tested whether prevalence of spondyloarthropathy increases with population density and group size, greater contact with soil, a slower host life history, increased ranging, dietary factors and body mass. We found general support for an effect of body mass, with larger bodied primates and carnivores exhibiting a higher prevalence of spondyloarthropathy. In addition, more threatened species experienced higher rates of spondyloarthropathy, with this association influenced by body mass and phylogeny. The effect of body mass could reflect that larger animals are exposed to more pathogens through greater consumption of resources, or that joints of larger bodied mammals experience greater biomechanical stresses, resulting in inflammation and activation of local joint infections.

Comparison of arthritis characteristics in lowlandGorilla gorilla and mountainGorilla beringei

Gorilla gorilla and the less-studied G. beringei occupy very different, geographically separate habitats. We studied the occurrence of various forms of arthritis to examine possible nature/nurture causality. The macerated skeletons of 38 G. beringei and 99 G. gorilla individuals were examined macroscopically for the presence of articular and osseous pathologies. Contrasting with only isolated osteoarthritis and infectious arthritis was the frequent occurrence of a form of erosive arthritis associated with joint fusion. Twenty-one percent of the G. beringei and 20% of G. gorilla specimens were afflicted, which are statistically indistinguishable frequencies. While both had prominent axial disease, they differed in patterns of peripheral arthritis. Whereas G. beringei showed a pauciarticular pattern, the pattern in G. gorilla was more often polyarticular. Susceptibility to spondyloarthropathy was apparently genetically imprinted before Gorilla separated into G. gorilla and G. beringei. However, the different patterns of peripheral joint involvement suggest a causality resulting from lifestyle (e.g., the presence/absence or extent of knuckle walking) or a habitat-related infectious agent.

Degenerative joint disease in African great apes: an evolutionary perspective

Degenerative joint disease is investigated in the spine and major peripheral joints (shoulder, elbow, hip and knee) in samples of chimpanzees (Pan troglodytes schweinfurthii; P. troglodytes troglodytes), lowland gorillas (Gorilla gorilla gorilla), and bonobos (P. paniscus). The P. troglodytes schweinfurthii sample comes from Gombe National Park, Tanzania, while the other samples are derived from museum materials originally collected in west/central Africa. Total data for African ape samples include 5807 surfaces for ascertainment of vertebral osteophytosis, 12,479 surfaces for determination of spinal osteoarthritis, and 1211 joints for evaluation of peripheral joint osteoarthritis. All apes display significantly less spinal disease than in a comparable human sample, and these differences are most likely a consequence of human biomechanical adaptations for bipedal locomotion. Apes are also generally less involved in the major peripheral joints than are humans, but human groups are themselves highly variable in prevalence of peripheral osteoarthritis. These data agree with other findings of low prevalence of degenerative joint prevalence in free-ranging apes, but contrast markedly with evidence derived from colony-reared Old World monkeys.