Retrieval Analysis of Polyethylene in Total Knee Arthroplasty in Thailand: A Case Report

Abstract

Objective: Retrieval analysis is one of the effective methods that can provide the information on in-vivo characteristics of wear implants. The clinicians can correlate the damage pattern from this method with other findings in a reproducible manner. Nevertheless, there has been no previous retrieval analyses of PE wear in total knee arthroplasty (TKA) in Thailand. Case Presentation: A 80-year-old female underwent left TKA due to osteoarthritic knee in 1994. She was 135 cm in height and weighed 42.7 kg. The cemented posterior stabilized press-fit condylar (PFC) (Depuy, Warsaw, IN, US) total knee system was used. Patellar resurfacing was performed with a cemented all-polyethylene implant. The femoral component was cobalt-chrome, while the tibial component was titanium alloy. A 12.5-mm thickness of stabilized plus tibial insert was used. After surgery, her knee had functioned well for 20 years. One year ago, she had intermittent swelling and effusion of the knee, together with occasional pain. The symptoms had gradually progressed with increasing episodes of giving way. She was diagnosed with aseptic loosening of TKA and consequently underwent revision TKA in 2014. All components were removed and retrieval analysis of PE tibial insert was performed at the National Metal and Materials Technology Center (MTEC), Thailand. Wear assessment of the articulating and non-articulating surfaces was performed in 16 zones. We found that PE wear was present in 11 zones without any backsides wear. The stereomicroscopy was performed, in which the scratches and delamination of the PE surface were demonstrated. The specimen was cut and analyzed using a scanning electron microscopy (SEM) to observe the insides of PE. Delamination, subsurface cracking and damage were identified in the damaged zones. In the metal part of PE, the surface damage and metal wear debris were also displayed using SEM. Conclusion: This retrieval analysis could demonstrate various modes of wear on UHMWPE. However, we propose that future studies, which are based on the association between wear of UHMWPE and possible precipitating factors, are mandatory.

Keywords

• Retrieval analysis
• mode of failure
• fail total knee arthroplasty
• wear assessment
• (Siriraj Med J 2018;70: 175-177)