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Joint Resurfacing & Joint Replacement
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Joint Resurfacing & Joint Replacement

As a person ages, particularly from 40 years onwards, there is an increasing chance if they have the unfortunate factors of genetics, a period of obesity or high knee stress activity that they will develop pain in the joints that will not respond to non-operative treatment. This will most likely be due to wear and tear of the cartilage – the thin tissue layer that coats the surfaces of joint bones—you may have seen this on the end of chicken bones. When cartilage is damaged, pain and ultimately disability may occur. This is known as degenerative joint disease or osteoarthritis.

In the early stages of cartilage degeneration, small potholes or cavities can develop—see other chapters on how this “potholes” can be treated. As you are reading this chapter, you probably no longer have isolated “potholes”, but rather the entire “road” of your knee is involved. With current cartilage restoration options, there are no reliable biological treatments. That is ‘bone-on-bone’ arthritis typically requires alternative management.

Once this stage is reached, common cartilage repair procedures that could otherwise help repair the damage (such as ACI or other transplantation or graft procedures explained on this website) are no longer effective. In such cases, reshaping or replacing the joint (arthroplasty) or invasive procedures that cut, shorten or realign the bones (osteotomy) are considered. It is therefore important to monitor and treat these problems at an early stage, whenever possible.

A recently developed technique has the potential to plug these defects with small metallic inserts – similar to a larger-scale version of tooth filling in dentistry. The technique falls under the umbrella of ‘joint resurfacing’. While it is effective in cartilage problems, the plugs are not cartilage. It is therefore not the same as dedicated cartilage repair procedures that replace, stimulate or re-grow the body’s own cartilage tissue.

Arthroplasty and joint resurfacing procedures are most appropriate for people age over 40–50 years or older who, after assessment, have minimal or low probability of successful biological cartilage repair. Alternatively, joint resurfacing is indicated for people with failed cartilage repair procedures and are age appropriate for “metal and plastic”.

Patients who are obese, heavy smokers, or receiving prescription painkillers typically not only have poor cartilage repair outcomes but also less optimal outcomes for arthroplasty. For these patients there are no reproducible, quick or easy procedures.

People with physically demanding work lives, or those with an active personal lifestyle, are better suited to osteotomy and/or cartilage repair, where possible.

If the damage to the cartilage is irretrievable, too extensive or the patient’s lifestyle or career is more sedentary (e.g. office worker), joint arthroplasty (using a prosthesis) may be preferred. However, the individual’s circumstances will need to be assessed by the surgeon.

A tailor-made treatment and rehabilitation plan will be planned, depending on the diagnosis made by the surgeon. To understand more about the specific joint problem, and help decide which procedures are suitable, a ‘weight-bearing’ (that is, standing) X-ray is essential.

Taken while standing up and gently squatting, this assesses the joint under normal body loads. In other positions – such as lying down on the X-ray table – the imaging results can give a misleading impression of the alignment and joint spaces. Your surgeon will be happy to answer any questions you have about your diagnostic X-rays.

Intended audience

This article is intended for anyone suffering from damage to their articular cartilage and their families who would like to find out about arthroplasty and joint resurfacing, as well as anyone interested in cartilage problems.

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Knee Resurfacing

What is arthroplasty?

If it is decided that a joint needs surgical artificial replacement, partial or total arthroplasty implants (metal and plastic) may be used, depending on the extent of the damage.

Taking the knee as an example, there are three major compartments that are commonly replaced: medial (towards inner thigh), lateral (outer side of leg) and patellofemoral (frontal, between the kneecap and thigh bone). Depending on need, dedicated replacements can be implanted separately into one or two of the compartments, or all three can replaced with a single total knee arthroplasty. More recently, bi-compartmental designs that fit two compartments with one single implant have also been developed, yet scientific scrutiny is need to tell if these are in the best interest of patients.

In addition, modern advances mean that it is now possible to perform a scan on a patient’s knee and send this information remotely to a prosthetic manufacturer. They can then custom-make a patient-specific implant with a unique fit, yet these “custom” implants have NOT been shown to be superior to standard implants.

What are the advantages of arthpoplasty?

Prosthetic replacements of knee compartments have been introduced since the 1970s and have highly reproducible results.

Single (unilateral) replacements of one part of the joint have a high degree of patient satisfaction, with recovery times, pain levels and surgical risks (blood loss, for example) all somewhat better than for total knee replacements. In addition, partial replacements still allow a great deal of bone, cartilage and ligament to be retained, which helps the implant to feel more natural.

What are the disadvantages of arthoplasty?

Especially in the case of total knee replacements, reports of discomfort or a ‘fake’ feeling in the knee are often noted. In addition, arthroplasty may limit knee bending, and patients need to manage their expectations as to what range of motion and activity they will be able to achieve after implantation.

In general, active pursuits that require excessive pivoting, or turning, and/or weight bearing (that is, no running or jumping) should be avoided, as there is risk of loosening or failure of the implant.

It is important to note that the life of any arthroplasty implant before failure is approximately 10–20 years for unilateral implants and 15-25 years for total knee implants. With this in mind, it is preferable to postpone knee replacement until at least middle age, wherever possible, as this will help the implant to last at least till the patient’s elderly years. If revisions of total joint replacement are necessary, elderly patients especially might be at increased risk of complications such as infection, diminished motion and pain.

What is joint resurfacing?

Joint resurfacing systems such as small metal implants are one surgical method for the treatment of cartilage defects in the major joints. In simple terms, it is a method for plugging cavities in the cartilage, to fill the defects and create a smooth and continuous surface using metal instead of a biologic.

Unlike bone replacement procedures, limited joint resurfacing ensures only minimal structural changes to the joint, and patients may be able to return to a normal, pain-free active life. While younger patients (less than 40 years of age) are likely to benefit from biological cartilage repair procedures, joint resurfacing is directed at those in their middle years (40–50 years of age) who require relief from painful cartilage joint problems, but do not have severe enough deterioration to require formal arthroplasty.

What are the advantages of joint resurfacing?

Patients undergoing joint resurfacing will be able to walk within a shorter time after surgery, and get back to activity soon.

What are the disadvantages of joint resurfacing?

The metal plugs that fill the cavities in the cartilage can create wear in the long term, and the long-term predictions are that there will be eventual failure years in the future. This is also true of other surgical approaches using synthetic components.

Consequently, the procedure should be considered more as an alternative for patients suitable for biological cartilage repair but otherwise are not suitable for candidates that do not require a full prosthetic implantation.

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