Does thickness of the polyethylene insert impact complications and revisions following total knee arthroplasty?

Prior literature is varied on the effects of polyethylene thickness on the results of total knee arthroplasty (TKA). The purpose of this study was to compare postoperative outcomes of patients who had TKA with composite tibial thickness of ≤10 mm versus ≥11 mm. This was an IRB approved retrospective review of 821 TKAs between January 2019 and December 2020. Exclusion criteria included pregnant/immunocompromised patients, bilateral or revision TKAs, and ≤12 months of follow-up. Demographic data, comorbidities, and postoperative complications -- such as superficial and deep periprosthetic joint infection, periprosthetic fractures, all-cause revisions, and others – were reviewed. Following exclusions, 777 TKAs were available, of which 411 had a composite tibial thickness of ≤10 mm and 366 had ≥11 mm. There were no differences in age, sex, length of stay, or comorbidities noted between groups; however, thinner inserts were significantly associated with Hispanic patients (p = 0.01), and patients with a lower BMI (p = 0.01). There were a total of 38 complications (9.2 %) in the ≤10 mm group and 25 total complications (6.8 %) in the ≥11 mm group (p = 0.24). There was a significantly higher rate of patients requiring MUA (4.1 vs 1.1 %) in the thinner insert group (p = 0.01). There were 17 patients (4.1 %) in the ≤10 mm group that went on to revision surgery compared to 19 patients (5.2 %) in the ≥11 mm group (p = 0.50). Our results suggest that postoperative complications and revision surgery following TKA is not associated with polyethylene thickness.