Total hip replacement surgery is typically used to manage end-stage painful hip conditions such as arthritis.
Approximately 95% of patients who have hip replacement surgery report that they are satisfied with their new hip. Most patients who have had a hip replacement are unaware of their prosthesis during normal activities.
Hip replacements last a long time. 90% of hip replacements implanted 10 years ago and 80% implanted 20 years ago are still functioning(1-2).
Total hip replacement was first used routinely in the 1950’s and evolved rapidly through the 1960’s and 1970’s to become a successful and reliable operation. Further advances over the past 30 years have further improved the outcomes of total hip replacement surgery.
The native hip is a ball and socket joint. The ball, formed by the femoral head, is held in the socket, formed by the pelvic acetabulum, by muscles, ligaments and the joint capsule. Hip replacement surgery involves removing the arthritic or diseased bone from the socket and removing the femoral head. The parts of the bone removed are replaced by artificial, or prosthetic, components.
Components of a hip replacement:
Femoral stem
The femoral stem is a metal component fixed to the top of the shaft of the femur with either bone cement or press-fit fixation. My preference is to use bone cement for fixation as this has been shown to achieve long lasting results with lower early complications than press-fit femoral stems(1). The stem I choose to use for hip replacements has been shown to last decades: at greater than 30 years following surgery, less than 5% of these stems have been re-operated on for aseptic loosening3. The femoral stem is then fitted with a femoral head (the ball of the hip replacement; see image)
Acetabular Cup
The acetabular cup (the socket) is a metal component that is usually press-fit into the prepared pelvic acetabulum. I use a press-fit cup coated in hydroxyapatite this have been shown to achieve excellent long-term fixation(1, 4). The metal cup is then fitted with an acetabular liner (the socket of the hip replacement; see image)
Bearing surface
The bearing surface is the combination of materials used for the femoral head and the acetabular liner. A number of different bearing surfaces can be used for total hip replacement surgery. My preference is to use a polished metal femoral head and a highly cross-linked polyethylene liner, as this combination achieves reliable long-term outcomes while minimising the risk of unpredictable complications1. More information about bearing surfaces in total hip replacement can be found by clicking here.
References
1. Graves S, deSteiger R, and Davidson D, Hip and Knee Arthroplasty. Annual Report 2012. Australian National Joint Replacement Registry, 2012: p. 1-220.
2. Franklin J, et al., Revision and complication rates in 654 Exeter total hip replacements, with a maximum follow-up of 20 years. BMC Musculoskelet Disord, 2003. 4: p. 6.
3. Ling RSM, et al., The long-term results of the original Exeter polished cemented femoral component: a follow-up report. The Journal of Arthroplasty, 2009. 24(4): p. 511-7.
4. Shepperd J and Apthorp H, A contemporary snapshot of the use of hydroxyapatite coating in orthopaedic surgery. Journal of Bone & Joint Surgery, British Volume, 2005. 87(8): p. 1046.