Total hip replacement - the past, the present, the future (Video) Event as iCalendar

(Seminars)

03 August 2010

4 - 5pm

Venue: Level 5 Seminar Room, UniServices House, 70 Symonds Street, Auckland

A Bioengineering research seminar by Dr Rocco Pitto, Orthopaedic Surgeon

Total hip replacement (THR) was introduced primarily to relieve pain and to restore function in patients crippled with arthritis of the hip. Secondary objectives included optimized durability of implant fixation and the bearing surfaces, as well as a combination of optimized mobility and stability of the articular couple. Replacing the hip joint consists of replacing both the acetabulum and the femoral head. THR is currently the most successful and reliable orthopaedic operation with 97% of patients reporting improved outcome.

The first recorded attempt at hip replacement was carried out 1891 in Germany by Temistocles Gluck, using ivory to replace the femoral head. Understandably, early attempts at replacement of the hip joint were condemned as a result of poor materials and poor design.

The modern THR owes much to the early 60s work of Sir John Charnley at Wrightington Hospital in the UK He made three major contributions to the evolution of contemporary hip replacement: 1) the concept of low-friction torque arthroplasty, 2) the introduction of high-density polyethylene, and 3) the use of acrylic bone cement to secure implant fixation to bone.

Recently the use of uncemented THR components have become more popular. Cemented cups and stems are commonly used in older patients due to their lower cost, while more modern and longer-lasting cementless implants, often coated with Hydroxyapatite, are used in younger and more physically active patients. Other biomaterials for modern cementless fixation include grit-blasted titanium, titanium mesh, or trabecular metal substrate made from tantalum.

One other innovation made in THR is the introduction of highly-crosslinked UHMWPE; these implants have a higher compressive wear resistance which reduces overall wear and, once again, allowed the use of larger diameter femoral heads, thereby increasing the range of motion and lowering the risk of dislocation. On the other hand, bioceramics like aluminium oxide and, more recently, composites with zirconium oxide have also been successfully used for hard-hard pairing of the artificial joint, in particular for very young and active patients, including athletes.

After the pioneering age, THR has reached the mature time of high reliability and reproducibility, with very satisfactory long-term clinical outcomes. To achieve even better results, researchers and surgeons are today challenged and affected by the law of diminishing returns.

View the high resolution video (Opens in new window).