Total joint arthroplasty in younger patients: heading for trouble?

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are safe and effective surgical procedures for advanced degenerative osteoarthritis.

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Traditionally, the success of total hip and knee arthroplasty has been determined by the measurement of survival. In the Lancet, Lee Bayliss and colleagues

now introduce the use of lifetime risk as a novel approach to illustrate the risk of revision surgery following joint replacement. Lifetime risk data, which describe the probability of an event occurring over the course of a lifetime, is useful to patients, clinicians, and other health-care professionals because it is easier to convey and understand than the commonly used survival rates.

The lifetime risk of revision (LTRR) for patients over 70 years of age, most of the arthroplasty patient population, is low. Bayliss and colleagues

report an LTRR around 5% for both THA and TKA patients at age 70 years, and LTRR of reduced further above this age. However, a potential threat for less successful long-term outcome in patients over 70 years of age is the worldwide trend of increased use of cementless implants instead of cemented ones, which is paradoxical, as more and more reports show that in older patients this leads to higher revision rates and re-operation rates than with cemented hips.

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Explanations for this trend are the intensive marketing of the more expensive cementless implants by the orthopaedics industry, and the willingness of orthopaedic surgeons to adopt to the less time-consuming cementless surgical technique.

The introduction of larger heads, in an attempt to overcome dislocations, might also generate higher revision rates.

However, the real problem highlighted by Bayliss and colleagues is the increasing failure rates of both hip and knee implants at younger ages. This information is not new, but by using the LTRR, the problems faced by younger patients become painfully exposed. For patients aged 50–54 years, LTRR increases up to 29% for patients with THA and 35% for those with TKA, compared with the LTRR of around 5% in patients aged 70 years with large differences between male and female patients (approximately 15% lower LTRR for women).

What makes the situation even worse is the trend, partly driven by patient request, to perform THA and TKA in ever younger patients. By the year 2030, 52% of primary THAs and 55% of TKAs are projected to be implanted in patients younger than 65 years, with the strongest increase in patents aged 45–55 years.

As a consequence, the number of revisions is expected to increase dramatically.

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The reasons for the higher LTRR for young patients having THA and TKA are that these are often more complicated primary surgeries, because many patients have congenital, developmental, or traumatic anatomical abnormalities causing the early osteoarthritis, and the higher demands leading to wear and secondary loosening.

Revisions performed within 5 years after surgery are associated with higher re-revision risks,

and orthopaedic surgeons have very little data on the outcome of revision THA and TKA in young patients. To our knowledge, there are only two papers on the long-term outcome of revision THA in patients who were younger than 55 years at the time of their revision.

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One study reported an alarming survival rate of 63% at 10 years,

and the other, using a biological reconstruction technique with impaction bone grafting, showed more promising results with a 10 year survival of 87%.

The current trend to implant total hip and knee implants in ever younger patients, driven by the fact that the short-term outcomes in the first few years after surgery are mostly acceptable, could lead to many patients ceasing to be revisable, and these patients might become a large burden to society in terms of cost and disability. Both patients and surgeons need to be aware of this possibility, and postponing this kind of surgery, despite the realistic limitations of patients with osteoarthritis, should be considered more frequently.