Isolated polyethylene exchange may be less reliable vs. full component revision TKA
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Key takeaways:
- Isolated polyethylene exchange may be less reliable and durable vs. full component revision knee arthroplasty.
- Isolated polyethylene exchange may be warranted in specific cases.
Published results showed isolated polyethylene exchange was less reliable and durable compared with full component revision for patients with instability after total knee arthroplasty and should only be reserved for specific cases.
Researchers at Hospital for Special Surgery analyzed data from 280 patients who underwent either isolated polyethylene exchange (n = 181) or full component revision (n = 99) for instability after TKA between Jan. 1, 2016, and Dec. 31, 2020.
Researchers assessed outcomes at a mean follow-up of 32.8 months and included survivorship, re-revision, radiographic parameters, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, lower extremity activity scale, VAS pain scores and the Veterans RAND 12-item health survey (VR-12).
Results showed patients who underwent full component revision had higher survivorship vs. patients who underwent isolated polyethylene exchange at 2 years (99% vs. 92%, respectively) and 5 years (94% vs. 84%, respectively).
According to the study, researchers found no differences in KOOS JR scores between the groups at 6-week, 1-year and 2-year follow-ups. However, patients who underwent full component revision had better improvements in VAS pain scores and VR-12 scores at 1 year, as well as better improvements in KOOS JR scores at 2 years compared with patients who underwent isolated polyethylene exchange. Researchers also noted men had an increased risk for recurrent instability after isolated polyethylene exchange (HR= 3.3).
“Isolated polyethylene exchange was not as reliable or durable compared to full component revision for the management of postoperative instability,” the researchers wrote in the study. “These procedures should only be reserved in cases with competent collaterals and when component position, offset and rotation are optimized.”
Perspective
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Instability is one of the most common causes of failure after primary TKA. There are several variants of instability including varus/valgus instability, mid-flexion instability, flexion instability or global instability. In this study of 280 primary TKAs that underwent revision TKA for instability, the authors found that 5-year survivorship after isolated polyethylene liner exchange was 10% less than both component revision. In addition, patient-reported outcome scores were greater in patients who underwent both component revision compared with isolated polyethylene liner exchange.
The results from this study demonstrate that isolated polyethylene liner exchange should be reserved for select cases of global instability where the amount of instability is the same in flexion and extension. For cases of mid-flexion instability, varus/valgus instability, flexion instability or asymmetric global instability, both component revision more reliably leads to improved survivorship and clinical outcomes. Further research is required to determine what level of constraint is needed with both component revision for instability.
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