The feasibility of lower limb direct skeletal attachment: A pilot study.

摘要

This project attempted to determine if directly attaching artificial limbs to bone is a feasible alternative to existing prosthetic sockets. To address this question, this pilot study was conducted to develop a novel technique for the design and selection of a Direct Skeletal Attachment (DSA) device in a Yucatan micropig model. The goal of the pilot study was to address DSA feasibility and procure preliminary results to assist in obtaining funding for a large scale study in a statistically significant population.;The unique DSA device consisted of two stages. The first stage, the load-carrying stage, functioned to transmit the load between prosthesis and bone and consisted of an original press-fit design. The second stage, the skin-interfacing stage, functioned to maintain an immutable barrier to infection where the prosthesis exited the body using antimicrobial techniques not previously attempted.;To design and select an acceptable load-carrying geometry, three-dimensional computer models of the bone/implant systems were constructed. Bone remodeling theory in conjunction with Finite Element Analysis (FEA) was incorporated into the models to determine the effect of the implant designs on the bone.;The selected design for the load-carrying stage was a 21mm, Ti6Al4V press-fit implant. The skin-interfacing stage consisted of a Ti6Al4V rod and carbon collar where the device exited the body. The DSA device was fabricated for clinical and mechanical evaluation.;Mechanical evaluation consisted of a fatigue analysis of the device to determine the useful life of the system and failure mode. In addition, cadaveric pull-out testing was conducted to determine the bone/implant interface strength.;Clinical evaluation consisted of two trials in adult, female, hairless Yucatan micropigs. The DSA systems were implanted by orthopaedic surgeons using surgical tooling fabricated solely for device placement.;From the results of the pilot study, the technique devised to design and select the DSA device was believed to be acceptable. The mechanical evaluation revealed that the device was mechanically stable and interface strength was adequate to support clinical loading. The clinical evaluation revealed potential flaws in the surgical protocol.;In conclusion, the results of this study suggest DSA is feasible. However, clinical results were not conclusive.