Perhaps more than any other advance in orthopaedic surgery, total joint arthroplasty has improved the lives of millions of patients. Originally introduced in the form of hip replacement, nearly all of the major joints of the musculoskeletal system can now undergo arthroplasty, and total knee arthroplasty has established itself as one of the most successful interventions for reducing pain and improving function and quality of life. All total joint arthroplasties are associated with a risk of failure, and it is believed that, with the exception of the oldest patients, most individuals who undergo an arthroplasty will require a revision at some point during their lifetime. With total knee arthroplasty, advances in implant materials and design as well as operative technique have increased implant longevity and decreased the rate of revision to <5% within ten years.
As is typical of a successful intervention, surgeons who perform total knee arthroplasty recognize the need or opportunity to “push the envelope.” There is great demand for offering knee arthroplasty to younger, more active patients, and, in doing so, it is projected that the number of revision procedures will grow from the current annual incidence of 38,000 up to 270,000 by the year 2030. Thus, understanding the causes of failure will be essential for guiding future strategies.
In this month’s article by Bou Monsef et al., a systematic approach to identifying mechanisms of failure and appropriate treatment protocols for failed total knee arthroplasty are introduced. The authors make the important point that avoiding operative intervention before a diagnosis is made, even in cases of pain with no clear etiology, is essential. Individual discussions on the roles of infection, loosening and component failure, instability, stiffness, patellofemoral complications, and even neuromas are presented and placed in their proper perspective.
Indeed, one of the greatest frustrations in orthopaedic practice is the inability to identify the causative factors for a condition. The failure of a total knee arthroplasty may be associated with one or more contributing factors, including rare and unusual conditions such as the formation of heterotopic bone, the development of complex regional pain syndrome, the occurrence of hemarthrosis, and even hypersensitivity to certain metals. Interestingly, up to 17% of the general population expresses some sensitivity to the metals used in total knee implants such as nickel, chromium, and cobalt.
Failure of total knee arthroplasty can be devastating to the patient, but early diagnosis and careful systematic analysis of the potential etiologies can lead to a favorable outcome. This article provides a clear and concise approach to this problem and is a “must read” for surgeons who perform this operation now and the residents and fellows who will be caring for these patients in the decades to come.
Thomas A. Einhorn, MD, Editor