Hip replacement surgery can provide major relief of pain from injury and/or diseases like arthritis. Due to the hip replacement technology available today the rate of recovery and success steadily increases.
In the US in the recent past, the rate of hip replacements increased between 2000 and 2010 by just under 50%. This increased incident rate is also supported by strong success rates, with 90-95% of patients experiencing no need for revision surgery within the first 10-years of replacement.
The reason for the success and regularity of hip surgery today is due to the constant technological and operational improvements made possible by research and development. Today there are a large number of alternative devices to choose from, though there is no definitive consensus on which material or device is the outright best.
This is partly because the type of device opted for can be largely dependent on factors like age and general activity levels. Because of the durability of the new materials younger patients are also now better placed to get hip replacement surgery.
The types of hip replacement technology available on the market today are:
Metal is used for recapping or resurfacing of the joint as well as for the total hip replacement. The socket and the ball are made of stainless steel, titanium, chromium, cobalt or combinations of these. Because of metal's durability, MoM devices have been favoured to last longer than other hip implant materials.
The ball being larger on the MoM device, the hip joint is sometimes more stable and less likely to dislocate. The one drawback noted is the release of metallic ions into the surrounding area of the hip. Various improvements have been implemented to reduce the possible consequences of this reaction.
Polyethylene and Metal on Polyethylene, (MoP)
Polyethylene is a special type plastic. Hip prosthesis are usually metal structural pieces with plastic liners, where the surfaces of the ball and socket meet. Another variation is the metal ball that meets a plastic socket liner.
MonP, (metal on polyethylene), is the longest tried and tested bearing.
The newest form of polyethylene is called either Ultra Highly Cross-Linked Polyethylene, (UHXLPE), or Ultra High Molecular Weight Polyethylene, (UHMWPE). It is a stable and reliable plastic material with reduced risk for wear. MoP prosthesis are the most regularly used and the least expensive form of hip replacement technology.
Ceramic on Metal (COM), Ceramic on Ceramic (COC), Ceramic on Polyethylene (COP)
Ceramic hips of specialised and durable type of ceramic and come in ceramic on metal, ceramic on ceramic, and ceramic on polyethylene variants.
The ceramic prosthesis has nil proven side-effects on surrounding tissue, though ceramic components can fracture and break under extreme stress. However, over the last two decades, major improvements have greatly reduced the incidence of ceramic hip breakage. All-ceramic hip joints are now considered reliable and long-lasting so ideal for younger patients.
Having a stiff and painful hip can prevent you from doing even the simplest things in life. Activities, like walking or moving between the stove and the sink, can become so challenging your ability to look after yourself is compromised. If this occurs, slowly all the basic acts of self-care like shopping, eating, grooming, and even sleeping soundly, can become a burden. So all the things that once came so easily, become too painful for you function properly on a day-to-day basis.
Without the help of family, friends or some form of home-care help, people’s general experience of hip problems can be one of indignity and isolation. Even with help, there is always your loss of independence and the sometimes embarrassing loss of privacy. Both alternatives have serious downsides, so when your hip condition limits your movement to this extent, one humane option is to have total hip replacement surgery.
One of the great surgical advances over the last century is the total hip replacement. Total hip replacement revolutionised the treatment of hip ailments and is today one of the most successful, safe and reliable orthopaedic interventions in practice.
Prevalence and Benefits
In 2010 in the US, 332,000 total hip replacements were performed, while in Australia for the same year there were approximately 34,000. It is also estimated by the American Academy of Orthopaedic Surgeons, that 10 years after the surgery, 90-95% of people don’t need revision surgery. The success rate is similarly high in Australia. This means in both countries in 2010 at least one in a thousand people relied on a total hip replacement to remain active and self-sufficient.
When dealing with numbers like these, there are community benefits that go beyond the immediate personal benefits of the patient. By having the surgery, the patient’s sustained productivity and communal engagement have positive flow-on effects.
These effects increase the longer the patient's working life after surgery, so the younger the patient the more economic and social benefit. As the treatment gets more advanced, younger people are more regularly recommended and opting to have total hip replacements.
Since the introduction of total hip replacement surgery, the medical profession keeps on critically analysing operative practices to improve patient outcomes. This has meant procedures and the types of prosthesis materials used, have steadily become safer and more effective.
Total Hip Replacement Developments
The improvements made, since ivory was used in 1891 to replace the femoral heads of patients, have been numerous. Skin and other tissues, glass and then stainless steel, have all been used to replace degraded joint surfaces, in an attempt to make the movement of the hip joint smooth and pain-free.
In the 1960’s Sir John Charnley, designed what he called a 'low friction arthroplasty', which was in principle the same as the prostheses used today. His prosthesis came in three parts; a metal femoral stem, a polyethylene acetabular cup, fixed with acrylic bone cement. The feature of 'low friction', Charnley managed to achieve by the smaller surface area of his femoral head design.
Metal-on-polyethylene prostheses have become the most popular type and much of the hip replacement research carried out, has been done to improve on metal-on-polyethylene prostheses exclusively.
The most common problem to occur over the years with metal-on-polyethylene implants is the release of polyethylene particles into the surrounding tissue of the joint. Whereas, special treatment of the plastics used more recently, increases their wear resistance and limits the release of these harmful particles.
Metal-on-metal prostheses have regained favour since they were thought to potentially generate harmful metal ions. It is thought today that flaws in the early designs of metal-on-metal prostheses were the main reason for most of the difficulties associated with these implants, rather than the material they were made from.
Metal-on-metal prostheses are much more durable than polyethylene implants. Due to this feature the femoral head can be made larger which increases the weight bearing stability of the implant.
The use of ceramic-on-ceramic prostheses was adopted to reduce friction and wear. Ceramic-on-ceramic implants are hard and scratch resistant, and respond well to moisture. All these features limit the possibility and effects of friction. Loose ceramic particles are also inert and benign in comparison to polyethylene and metal debris when released into the body.
Because ceramic-on-ceramic prostheses are comparatively wear-resistant, they are more commonly used for younger and more active patients. They are, however, more expensive and require precise surgical insertion to avoid chipping and dislocation, both of which, can compromise the success of the implant.
An example of a joint effectively treated using arthroscopy is the hip. Though, in the case of severe impact damage or advanced osteoarthritic degeneration, arthroscopy is used more as a diagnostic tool. Here, the emphasis of arthroscopy is to fine-tune the medical understanding of a condition after completing X-Rays. The more detailed aspects of a hip condition can be gauged by arthroscopic observation and the need for a replacement, enacted on according.
Hip replacement is a surgical intervention appropriate for irreversible conditions. The nature of how a hip replacement is done can vary considerably in the amount of the joint and bone that is removed and then replaced. The two most common variations of hip replacement are the half, (or hemi), hip replacement and the total hip replacement.
The joint bones of the hip are the acetabulum and the femoral head. With a total hip replacement both are removed and replaced with a prosthetic implant: a ball and socket configuration. The medical term for this procedure is arthroplasty. With the half hip replacement, (or hemiarthroplasty), the femoral head is the most common side of the joint to be replaced.
The acetabulum is a concaved formation of bone on the lower, side faces of the hip bone. In anatomical terms, the acetabulum sits almost at the lateral conjunction between the ilium, (which is the upper open planed section of the hip), and the ischium, (comprising the lower and side boundaries of the hip).
The surface area of the opening of the acetabulum would be smaller than the palm of a person’s hand. Within the opening, it forms a neat socket with a narrow extension, or finger of bone, that curls to hug the ball of the femoral head. This bone creates the back and lower lip of the opening.
For the half hip replacement, the femoral head is predominantly the side of the joint replaced first. The femoral head is the highest end of the thighbone, (the femur), and has a distinctive head and neck shape to fit neatly into the joint socket of the acetabulum.
What makes up a hip?:
Both the ilium and the ischium constitute about 40% of the total mass of the hip bone. The pubis region of the hip bone is located at the midline of the hip and makes up the last 20% of the hip bone as a whole.