Revision UKA to TKA, revision TKA to TKA yielded similar outcomes

Deep infection was significantly greater among patients in the TKA to TKA revision group.

Issue: November 2016

Patients who underwent unilateral knee arthroplasty revised to total knee arthroplasty experienced similar outcomes to patients who underwent revision total knee arthroplasty to total knee arthroplasty, despite total knee arthroplasty to total knee arthroplasty being a more difficult procedure with a higher percentage of re-revisions, according to study results.

Perspective from Emmanuel Thienpont, MD, MBA, PhD

“Patients can be reassured the functional and survivorship outcomes of primary [total knee arthroplasty] TKA revised to TKA do not appear to be much different than those of primary [unilateral knee arthroplasty] UKA revised to TKA,” Tesfaye H. Leta, MPhil, of Haukeland University Hospital, told Orthopedics Today.

Tesfaye H. Leta

Revision TKA

Utilizing the Norwegian Arthroplasty Register between 1994 and 2011, Leta and his colleagues identified 768 failed primary TKAs and 578 failed primary UKAs, all of which were revised to TKAs. Patient-reported outcome measures (PROMs) used included the EuroQol EQ-5D, the Knee Injury and Osteoarthritis Outcome Score (KOOS) and VAS assessing satisfaction and pain. To assess the survival rate and risk of re-revision, researchers performed Kaplan-Meier and Cox regression analyses adjusting for propensity score and multiple linear regression analyses to estimate the difference between the two groups in mean PROM scores.

Overall, 12% of patients in the UKA to TKA group and 13% in the TKA to TKA group underwent re-revision. At 10 years, survival was observed as 82% in the UKA to TKA group vs. 81% in the TKA to TKA group. Although researchers found no difference in the overall risk of re-revision for UKA to TKA vs. TKA to TKA or in the PROM scores, patients in the TKA to TKA group older than 70 years at the time of revision had a two-times higher risk of re-revision. Major causes of re-revision for UKA to TKA vs. TKA to TKA included a loose tibial component (28% vs. 17%), pain alone (22% vs. 12%), instability (19% vs. 19%) and deep infection (16% vs. 31%). Only deep infection, however, had observed differences between groups and was significantly greater in the TKA to TKA group. Compared with UKA to TKA, TKA to TKA was a longer surgical procedure with more procedures requiring stems and stabilization.

“Many orthopedic surgeons prefer to use UKA for younger patients and postpone TKA, believing the results of [revision] rev-UKA are equal to those of primary TKA and better than those of rev-TKA,” Leta said. “In our study, we did find similar overall functional and survivorship outcomes between rev-UKA and rev-TKA, but a significant difference in survivorship in the age-stratified analysis with a greater risk of re-revision for rev-TKA among those who underwent revision at an age of more than 70 years. Thus, it seems if UKA is to be used, it may be more appropriate for older patients.”

Future research

Leta noted the retrospectively collected PROM data in this study was limited to approximately 20% of the total 1,346 revision cases. In total, 314 patients who had undergone aseptic revision knee arthroplasty between January 1994 and September 2005 were asked to participate in the survey. Of these, 277 patients responded to the questionnaire, yielding a response rate of 85.5%.), making further clinical outcomes studies with prospective preoperative and postoperative PROM data warranted.

“Because PROM is a subjective instrument, further outcome studies which involve objective assessment method such as performance-based measures, are also warranted,” Leta said. “Furthermore, in this study, the outcomes of revision knee arthroplasties performed due to infection of the primary implant was not studied. As a result, the overall success or failure rates in the treatment of first-time revision UKA vs. TKA due to deep infection need further study.” – by Casey Tingle

Reference:
Leta TH, et al. J Bone Joint Surg Am. 2016;doi:10.2106/JBJS.0.00499.

For more information:
Tesfaye H. Leta, MPhil, can be reached at The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Jonas Lies vie 65, 5021 Bergen, Norway; email: tesfaye.hordofa.leta@helse-bergen.no.

Disclosure: Leta reports a grant from the Department of Orthopedic Surgery at Haukeland University Hospital.

Perspective

Emmanuel Thienpont, MD, MBA, PhD

We wrote a recent narrative review that will be published in the January 2017 issue of the Bone & Joint Journal. Our conclusions are in concordance with the important findings of Leta and colleagues.

Revision of unicompartmental knee arthroplasty (UKA) is often possible, two-thirds of the time, into a primary total knee arthroplasty (TKA). The exception is if the cause of revision is early failure due to important technical mistakes made by the index surgeon or if disastrous polyethylene wear led to critical bone loss. In both such cases, the use of bone substitution with wedges or cones and stems to increase fixation might be necessary, and these types of implants can hardly be considered a primary TKA.

Furhtermore, the study by Leta and colleagues shows that aseptic loosening (ASL) and instability remain major causes of failure of UKA and are linked to the technical capacities of surgeons. Training and education, as well as performing a minimum amount of UKA cases, remain key.

We must be careful with the indication of re-revision of TKA for ASL. Often radiolucent lines are observed not because of loosening, but because of the difference in bone elasticity between the more distal tibial bone and the absence of cement penetration in sclerotic bone. This study shows furthermore that many UKAs are still revised for unexplained pain, which remains a further issue after revision. It must be emphasized that surgeons should understand the principles of pain before indicating revision for pain only.

Finally, this study shows revision of TKA leads to many more infections than revision of UKA. Therefore, if we know the risk of infection is three-times higher for primary TKA than for UKA, it sheds new light on this important complication.

In conclusion, our review showed that in two-thirds of cases, revision with primary TKA components is possible after failed UKA and leads to [a] better functional outcome than with revision TKA.

Reference:

Grosu I, et al. Knee Surg Sports Traumatol Arthrosc. 2014;doi:10.1007/s00167-013-2750-2. Review.

Emmanuel Thienpont, MD, MBA, PhD

Orthopaedics Today Europe Editorial Board member

Disclosures: Thienpont reports he is a consultant for Lima, Medacta and Zimmer Biomet and receives royalties from Medacta and Zimmer Biomet for products related to UKA.