Joint Replacement

Key Objectives
To evaluate the process and outcomes of joint replacement surgery to ensure that clinical management of joint replacement patients, including the selection of joint replacement prostheses, is based on objective and valid scientific evidence.

Major Research Interests

• Complications of joint replacement
• Patient outcomes evaluation
• Bone loss around implants and aseptic loosening
• Reconstructive techniques for treating major bone deficiencies at revision joint replacement

Summary
Relative to other elective surgical procedures, hip and knee replacement surgery are cost-effective procedures and the early post-operative medical complications, such as infection and thromboembolism, are no longer important problems. However, failure of joint replacement prostheses results in poor health outcomes. Failure, most commonly due to aseptic loosening of the prosthesis, is often associated with pain and deterioration in joint function. Consequently, activities of daily living are impaired and health related quality of life is markedly compromised.

The contemporary issues for joint replacement are predominantly technical and include the operative techniques, post-operative management protocols and most importantly, the choice of prosthesis. The Joint Replacement Clinical Research Program utilises randomised clinical trials and large scale prospective monitoring of cohorts of patients undergoing total joint replacement, to obtain health outcomes data to evaluate the effectiveness and efficacy of different implant designs, and other aspects of patient management protocols. Evaluation and development of diagnostic techniques for diagnosing or monitoring complications of joint replacement is also a key research activity.

We have developed a novel CT based method to image bone loss around metal prostheses, which is enabling us to study the progression of osteolysis (see fig). In an integrated program of research we are also measuring the migration and wear of prostheses using sophisticated new programs and digitised x-rays. Musculoskeletal imaging for diagnostics and research has also been enhanced by the implementation of a radiostereometric analysis facility in the Discipline.

Radiostereometric analysis (RSA) of hip replacement

Revision surgery to replace the failed prosthesis is complex, with the patient often requiring major bone grafting due to significant bone loss. Revision surgery is also associated with a higher risk of complications and mortality and prosthesis survival decreases with each subsequent revision procedure. As a tertiary referral centre for complicated revision joint replacement cases, the Discipline is evaluating different operative techniques and biological and pharmacological measures for the management of bone loss.

Computerised tomograph of a total hip replacement showing osteolysis (bone loss) around the screws of a metal-backed acetabular implant.

Director of Program
Professor Donald Howie

Email: donald.howie@adelaide.edu.au

Location:
North Wing, Room 3C-20 and L4 Bice Building Orthopaedic Outcomes Unit.

Staff:
Susan Pannach (Outcomes Coordinator), Margaret McGee (Researcher Co-ordinator), Kerry Costi, Oksana Holubowycz, Tania Knight, Susan Neale, Roman Stamenkov, Angie Bosnakis, Stuart Callary, Visiting Arthroplasty Fellow. Angelo Carbone, Rijan Scholten, Melina Dalese, Angela Standen, Joint Replacement Nurse.

Wear

Key Objectives
To characterise both the response of bone and associated tissues to the implantation of joint replacements and the effect the body has on the implanted materials and to use this information to make recommendations for changes in implant design, materials and surgical techniques.

Major Research Interests

• Prosthesis wear and periprosthetic bone loss
• Biomaterials evaluation
• Inflammatory mediators
• Biological induction of bone formation

Photomicrograph of bone close to a failed implant showing osteoclastic bone resorption (arrows).

A major concern in joint replacement surgery is periprosthetic osteolysis (bone loss/bone resorption) which leads to aseptic loosening of prosthetic implants.

Radiographic studies and implant retrieval analyses have been used to establish the relationship between excessive wear of different implant designs and implant failure. This research encompassing in vitro, in vivo, implant analysis and histological investigations examines the wear of joint replacement implants and the biological response to wear particles derived from these materials. We are examining the cause for bone loss around joint replacement prostheses which we hypothesise is as a result of bone resorbing mediator release from macrophages and bone cells in response to wear particles and products of degradation of prosthetic materials in the periprosthetic tissues. An understanding of the pathological processes causing bone loss around joint replacement prostheses will allow us to develop treatment options.

The Discipline's Implant Retrieval Program provides a large collection of implants and periprosthetic tissues removed at revision surgery for these wear studies. Working with the Bone Cell Biology Group provides us with molecular biology and in-situ hybridisation probes that improves the sensitivity and detection limits of mediator production.

Information collated from clinical, radiographic and pathological studies is used to determine factors involved in loosening of prostheses. Using our sheep hip replacement model, we undertake pre-clinical evaluation of new biomaterials, pharmacological and biological agents for applications in joint replacement.

Directors of Program
Professor Donald Howie
Email: donald.howie@adelaide.edu.au
Dr David Haynes (In-vitro wear)
Email: david.haynes@adelaide.edu.au

Location
Adelaide University Medical School
Rm N228 Implant Retrieval Laboratory
Rm N222 Implant Analysis Laboratory
Rm N222 Mechanical Testing Laboratory
Cytokine Laboratories Dept. of Pathology

Staff
Implant Retrieval and Analysis and Mechanical Testing Laboratories: David Thompson, Angelo Carbone, Margaret McGee, Corinna Wildenauer.
Sheep Hip Arthroplasty Program: Angelo Carbone, Warrick Bruce (Consultant Veterinary Surgeon)
Wear: David Findlay, Margaret McGee, Roman Stamenkov, Visiting Arthroplasty Fellow.
In-vitro Program: David Haynes, Chris Holding, Helen Dassios.