In 1972, the Mayo Clinic Department of Orthopedic Surgery opened a new frontier of diagnosis and treatment of wrist injury with the classic paper by Ronald L. Linscheid, M.D., and James H. Dobyns, M.D. In it, they set forth a pathomechanical framework for understanding carpal instability that influenced many subsequent therapeutic wrist advances, leading ultimately to wrist joint replacement.
Explains William P. Cooney III, M.D., Mayo Clinic emeritus hand and wrist surgeon whose team developed the total wrist implant: "Mayo's novel conceptualization of wrist instability related to carpal bone malalignment, ligament laxity, and secondary arthritis helped pave the way for the emergence of advanced prosthetics."
Orthopedic surgeons formerly relieved pain and dysfunction from osteoarthritis and rheumatoid arthritis by modifying bone, such as removing the trapezium or the distal end of the ulna, or by fusing the wrist bones. But the functional outcomes were limited.
"The important principle that Mayo contributed was the idea that prostheses, such as the total wrist, the distal ulna, or the thumb joint, usually can closely restore the normal anatomy—and anatomic correctness and joint integrity optimize function," adds Richard A. Berger, M.D., Ph.D.
Says Dr. Cooney: "We are now seeing the initial success of this approach, proving that biomechanically and clinically, wrist replacement tends to be a much better solution than just cutting away bone or stiffening of bones (wrist fusion) at the expense of the joint architecture."
Specialists across disciplines contributed to Mayo's wrist advances, including earlier work on the lower extremities. "We really benefited from the work of Dr. Mark Coventry and his group's 1969 total hip replacement," Dr. Cooney says. Mayo's work on the joint replacement of the hip and knee helped to refine the collaborative research method and culture between clinical-surgical care and bioengineering.
At Mayo, the team approach, basing investigative ideas on orthopedic anatomy and biomechanics, originated with Edmund Y.S. Chao, Ph.D., and continues today with Kai-Nan An, Ph.D., and his group of biomechanical engineer collaborators. Clinical orthopedic problems are translated into mechanical problems with engineering solutions — and then translated back into the clinical context and applied to patient care.
"Joining the 2 cultures enabled us to work more easily with production companies so we could put ideas into practice faster," Dr. Cooney says. "Following this model has led to great advances in hand and wrist surgery in the past 10 to 15 years."
Dr. Cooney recalls the collaboration with engineers as an intellectually stimulating and highly productive time. It led to some 20 years of research supported by the National Institutes of Health investigating biomechanical and kinematic forces in the hand and wrist in healthy patients, in those with disease, and in cadavers and anatomic models.
The investigations included wear-force characteristics evaluated in a custom-designed wear-testing machine that simulated the loading and motion of the wrist from flexion, extension, radioulnar deviation, and axial rotation.
"Our solutions did not come right away, but then, the wrist is quite different from other joints," Dr. Cooney says. "It's kind of a Rubik's Cube with 8 bones in it, whereas the hip is a ball-and-socket joint. But eventually our work all came together in this new vision of wrist replacement."
Introduction in 2006 of instrumentation to facilitate correct anatomic placement of a total wrist implant
Development of a metallic ulnar-head implant for patients with unstable forearms secondary to excision of an arthritic ulnar head