Hip Replacement Patent

One of the most important innovations in orthopaedics in the last 50 years is total joint replacement. Total hip replacement has been referred to as "the most successful orthopaedic procedure." Hip replacement is considered the treatment of choice for painful, end-stage arthritis and more than 150,000 procedures are performed in the United States each year. Although the 10-year survivorship statistics for hip replacement are quite good, improvements in implant designs remain an important goal if implants are to survive for the lifetime of the typical patient and if joint replacement surgery is to be routinely performed in younger and more active patients with end-stage joint disease.

On May 8, 2000 the United States Patent Office issued a Notice of Allowance for a patent application entitled "Prostheses Having Curvilinear Collars." The inventors of this technology are: Dennis R. Carter, PhD; Jay A. Mandell, PhD; Gary S. Beaupré, PhD; and David J. Schurman, MD. This patent is an outgrowth of a series of VA-supported investigations into the mechanobiology of bone adaptation before and after total joint replacement. These VA-supported investigations include:

Mechanical regulation of skeletal tissue in normal and prosthetic joints; Co-PI: Dennis R. Carter, PhD and Gary S. Beaupré, PhD; VA Rehabilitation Merit Review project A501-2RA.

Mechanical regulation of peri-prosthetic tissue differentiation; Co-PI: Dennis R. Carter, PhD and Gary S. Beaupré, PhD; VA Rehabilitation Merit Review project A501-4RA.

The computational modeling that established proof of concept and performance characteristics for this invention was done by Jay A. Mandell, PhD as part of his Stanford PhD thesis work on Load Transfer in Cementless Intramedullary Prostheses. Using finite element analysis and bone remodeling simulation software, Dr. Mandell demonstrated that our new prosthesis collar design should reduce prosthesis subsidence and improve the distribution of stress at the prosthesis collar/bone interface. These improvements should result in a reduction in adverse peri-prosthetic bone remodeling, a reduction in the risk of prosthesis loosening, and a reduction in the rate of revision surgery.

The clinical success of a closely related prosthesis design is documented in a publication by David J. Schurman, MD (Barber TC, Woolson ST, Goodman SB, Schurman DJ: Flat versus conical collar in cemented total hip arthroplasty: radiographic outcome in osteoarthritic hips. Contemporary Orthopaedics, 32(4):245-248, 1996).

Pending formal issuance of the patent, our plans are to work with Stanford's Office of Technology Licensing to negotiate a licensing agreement with an orthopaedic implant company that will manufacture and market the prosthesis in the United States and worldwide.