Image: The evolution of the hip joint (Photo courtesy of Oxford University/OOEG).
New interactive three-dimensional (3D) models of human joints show how common medical complaints have arisen, and how humans are likely to evolve in the future.
Created at the University of Oxford (United Kingdom), the 3D computer models were generated by compiling 128-slice computerized tomography (CT) scans of bones from humans, early hominids, primates, and dinosaurs. In all, the researchers scanned 224 bone specimens, spanning 350 million years from the Devonian period to the modern day. They then used spatial engineering and mathematical methods to provided new insights into morphological trends associated with common orthopedic complaints, such as anterior knee pain and shoulder pain.
For example, as species evolved from moving around on four legs to standing up on two, the so-called neck of the thigh bone grew broader to support the extra weight; and the thicker the neck of the thigh bone, the more likely it is that arthritis will develop. In the shoulder, the researchers found that an anatomical gap through which tendons and blood vessels normally pass through got narrower over time, making it more difficult for tendons to move, which could explain why some people experience pain when they reach overhead.
The samples used in the study were of joints located in the shoulders, hips, and knees of amphibious reptiles dinosaurs, shrews, tupaiae, lemurs, primates, A. Afarensis (known as Lucy), Homo Erectus (the Turkana Boy), and Neanderthals. By comparing the modern and ancient samples, the researchers hope to gain a better insight into the origins and solutions to common orthopedic complaints. In addition, extrapolation of these morphologic trends has allowed the 3D printing of possible future skeletal shapes as humans evolve.
“Throughout our lineage we have been adapting the shape of our joints, which leads to a range of new challenges for orthopedic surgeons. Recently there has been an increase in common problems such as anterior knee pain, and shoulder pain when reaching overhead, which led us to look at how joints originally came to look and function the way they do,” said lead author Paul Monk, MD, PhD, of the Oxford Orthopaedic Evolutionary Group (OOEG). “These models will enable us to identify the root causes of many modern joint conditions, as well as enabling us to anticipate future problems that are likely to begin to appear based on lifestyle and genetic changes.”
University of Oxford