HipHub (OT 03/31 project) - final seminar

Prediction and evaluation of
total hip replacement performance:
can we plan success?

June, 22nd - 23th, 2007
Groot Begijnhoof
Leuven
Belgium

Download the seminar leaflet here (pdf)

Go to the HipHub seminar webpage.

Download the seminar proceedings here (pdf)

OT 03/31 project

Summary of the objectives

The role of biomechanical parameters in the success or failure of endoskeletal implants will be studied. The scope of the research is focussed in two ways:

• Only cementless fixation (by osseointegration) of total hip replacements (THR) will be studied. In contrast to oral implants, osseintegration of orthopaedic implants is now reported to be less evident. This in contrast to optimistic early reports. The key difference between the two fields is the necessity of immediate loading of the implant in the orthopaedic field, while immediate loading of the implant is elective in the oral field. Studying cementless THR allows direct application of the study findings to the younger patient population for which cemented fixation is not an option. As the whole western population is aging and the incidence of THR in younger patients is increasing (Soderman 2001) a longlasting THR will have an increasingly more profound socio-economic impact.
• The proposed research focuses on primary fixation during the healing phase and the next few months, until a stable interface between implant and host bone has been realised. The effect of the initial healing phase on the long-term failure or success is an essential part of the study.
  

Several authors analysed stress strain distribution at the bone implant interface to study the stability and fixation of hip replacements. Recent research revealed the necessity to include muscle forces in the analysis (Kassi 2002). An important innovative aspect of the proposed research is therefore the accurate modelling of the muscle forces and its role in the bone remodelling and consequent integration of the prosthesis into bone.

The scientific objective of the proposed biomechanical analysis is to establish a relationship between biomechanical parameters, more specifically the load bearing capacity of an implant and the surrounding bone as well as the actual load during functional activity, and the quality of the initial fixation of the implant.
Additionally, the analysis of initial mechanical fixation will be validated and parameters obtained will be used in the validation of the methodology in a prospective patient study.

The proposed methodology should allow the identification of relevant clinical parameters and diagnostic tools in order to:

• Pre-operative evaluate and, if possible, improve the prognosis of the implant
• Per-operatively evaluate the local host situation and apply an optimised surgical technique and implant configuratio
• Post-operatively detect as early as possible symptoms of complications or failure, therefore allowing corrective intervention and avoiding unnecessary efforts and/or costs.

The clinical outcome should be formalised as:

• Improved patient selection criteria
• Guidelines for optimised surgical techniques, including computer assisted pre-operative planning, navigation tools and robot-assisted surgery.
• Design rules for a new generation of implants
• Improved protocols for revalidation

The present study will contribute to the causal analysis of implant-bone interface loading during functional activity caused by muscle activation and the resulting bone remodelling based on a retrospective patient study. A validation of the methodology based on a prospective study is foreseen.