Surface analysis of bilateral tibial inserts retrieved due to polyethylene wear and PCL-deficiency

•Wear features on both tibial inserts were delamination, scratching, and pitting, indicating oxidation-induced damage.•PCL deficiency increased roughness in the medial compartment but was not the primary factor in TKR failure.•A 7-month implantation difference led to significant oxidative degradation in the left tibial insert, lowering crystallinity.•Oxidative degradation in the left insert also caused reductions in molecular weight and microhardness. This paper investigates the surface damage modes found on bilateral tibial inserts (implanted for 137 and 146 months). This paper also investigated whether posterior cruciate ligament (PCL) deficiency can be considered an external factor that worsen wear and contribute towards total knee replacement (TKR) failure. Results show that pitting, scratching, and delamination were the dominant wear features on both inserts and surface roughness was higher on lateral compartments of both inserts. PCL deficiency contributed towards increased surface roughness in the medial compartment of the left insert but was not the main factor leading to TKR failure. The right insert showed oxidation index (OI) of 1.57, crystallinity of 88.95 %, microhardness of 5.55 ± 0.82 HV, and molecular weight of 30,975 g/mol. Meanwhile, the left insert exhibited OI of 2.99, crystallinity of 60.89 %, microhardness of 5.51 ± 1.51 HV, and molecular weight of 295,246 g/mol. Our study concludes that long-term implantation leads to more severe oxidation degradation of the inserts.