3D Scan of Bones Shows Joint Evolution

Patient after patient presenting with similar musculoskeletal disorders—shoulder impingement, hip arthritis, knee dislocation—led orthopaedic surgeon Paul Monk, M.D., to ask himself a series of questions: Why are these happening? Are these conditions getting worse? Are our bodies fit for their purpose? How will these conditions evolve? Believing that clues from our past could offer resolution and predictions, Monk went back 350 million years for answers.

Monk and a team of researchers at the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences at University of Oxford worked with the Smithsonian Institution in Washington D.C., the Natural History Museum in London and the zoology department at Oxford to make 3D CT reconstructions of 224 bone specimens. The 3D scans of knees, hips and shoulders were compiled into a morph that allows a viewer to see how the shapes of our joints have changed over time, and what they might look like 4,000 years from now. The model, known as the Trillennium Man, is available to access online.

    

trellenniumman2

The shoulder has changed shape as our ancestors
have evolved from papio anubis (left) to homo sapiens (right).

Device engineers and surgeons rightfully pride themselves on correcting musculoskeletal wear and deformities. The morphs provide current and future perspective on that work.

Perhaps the most striking trend was that seen in the hip. As we have moved from a quadrupedal to bipedal locomotion strategy, we see more bone in the femoral neck, and the head/neck ratio is rapidly trending towards that of arthritic patients.

In the shoulder, as we’ve gone from a quadrupedal to bipedal position, the pitch of the acromion has flattened and moved more anteriorly. “We know that tendons pass through that gap, and now there is less space for them to move,” Monk says. “That might explain why more and more people are presenting with impingement symptoms. We’ve had similar insights from other joints, including the knee.”

“We hope findings such as these will help inform the next generation of orthopaedic interventions,” Monk says. “This research highlights the musculoskeletal factors that are changing dramatically. It highlights which disease patterns need to be corrected, and provides other insights such as which parts of a knee prosthesis are the most important, and perhaps which parts of the arthroscopic procedure in the shoulder we should be addressing.”

Monk is already putting knowledge gained from the research to work. At AAOS, he presented research on ways that devices on the market don’t match the anatomy of the patellofemoral joint.

When we asked his thoughts on the greatest evolution in orthopaedics during his professional career, he mentioned the rise of custom implants. “We’re moving away from an era where ‘one shape fits all’ toward a personalized approach, a patient-specific solution. I have a feeling that will be one of the big changes during my career,” he says. “There will be more preparatory time and effort spent before we arrive in the OR to do the procedure. 3D prints of individual joints are already preoperative adjuncts. Routinely, I think we will see an extra cycle of engineering that occurs before we arrive in the OR, so that the operative solution is available by the time we start the operation. That is where this research can make its impact.”