No Clinical or Radiographic Differences Between Cemented Cobalt-Chromium and Titanium-Niobium Nitride Mobile-Bearing Unicompartmental Knee Arthroplasty

Purpose: This study aimed to compare the clinical and radiographic outcomes of patients with positive patch tests undergoing a medial mobile-bearing titanium-niobium nitride (TiNbN) unicompartmental knee arthroplasty (UKA) to patients undergoing standard UKA (cobalt-chromium [CoCr] implants).

Methods: Two successive groups of patients, amounting to a total of 246 individuals, who received Oxford (Zimmer-Biomet, Warsaw, Indiana, USA) UKA were included. The first group was composed of a series of 203 consecutive standard CoCr UKAs (Standard Group), while the second group comprised 43 consecutive hypoallergenic TiNbN UKAs (HA group). The patients of the second group had a positive epicutaneous patch test result for metals. Each patient was evaluated using the Oxford Knee Score (OKS) and Knee Society Score (KSS) a day prior to the surgery (T ₀) and at two consecutive follow-ups, namely T ₁ (minimum follow-up of 12 months) and T ₂ (minimum follow-up of 34 months). Radiographic measurements were performed at the final follow-up (T ₂).

Results: No statistical differences were noted between the two groups regarding demographic data (p > 0.05). No clinical or radiographic differences were found between the HA and standard groups at any follow-up (p > 0.05). A statistically significant improvement was found at any follow-up for both OKS and KSS (p < 0.05).

Conclusions: No clinical or radiographic differences between the hypoallergenic and standard cobalt-chromium groups at any follow-up were found, with a clinically significant improvement being experienced by both groups during the entire follow-up.

Level of evidence: Level II-comparative prospective study.

Supplementary information: The online version contains supplementary material available at 10.1007/s43465-021-00486-3.