Osseointegrated system for fixation of upper leg prostheses

PhD ceremony: Mr. P.K. Tomaszewski, 11.00uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Osseointegrated system for fixation of upper leg prostheses

Promotor(s): prof. G.J. Verkerke, prof. N. Verdonschot, prof. S.K. Bulstra

Faculty: Medical Sciences

Leg amputation is a permanent disfigurement, largely impacting the patients’ mobility, professional activity and quality of life. Traditional stump-socket fixation with its common soft-tissue problems, control and fitting difficulties, remains a limiting issue in patients’ rehabilitation. Alternatively, a direct osseointegrated attachment of an artificial limb to the skeletal system allows overcoming skin and fitting problems, provides a better prosthetic control and increased mobility. However, bone loss around the prosthesis, bone and implant failures and infections restrain applications of the current osseointegrated implants.

To overcome the biomechanical problems of the current designs, a new concept was developed. The aim was to restore the natural load transfer in the femur and allow implantations in short stumps. We hypothesized that an implant composed of a metallic core sliding in an elastic sleeve will reduce bone failure risk and bone loss.

Finite element analysis and experimental techniques were used to verify that the novel concept produced a more physiological stress and strain distribution in the bone, reduced failure risk and minimized long-term bone loss. Tribological experiments indicated that the optimal material combination for the new implant consists of diamond-like carbon coated PEEK polymer and titanium alloy. Insights into manufacturing feasibility and surgical procedure were gained in in-vivo trials. In conclusion, the new osseointegrated implant, developed within the framework of this thesis, will drastically reduce bone failure risk and adverse bone remodeling over the existing devices and will allow more patients to benefit from a direct fixation of external prosthetic systems.