Mid-term radiographic evaluation of a monoblock trabecular metal tibia following total knee arthroplasty in obese and morbidly obese patients

Background Indications for primary total knee arthroplasty (TKA) have become more inclusive of morbidly obese patients, however, higher rates of complications and lower implant survival have also been reported in this population. The purpose of this study was to investigate the mid-term survival, clinical, and radiographic outcomes of a cementless trabecular metal monoblock tibial component in severely obese patients. Methods This was a retrospective study of class II and III obese (BMI > 35) patients who received a cementless primary TKA. Standing radiographs were assessed for the presence of progressive tibial radiolucent lines (RLL), and clinical measures were assessed at least 2 years post-operative via the Oxford Knee Score (OKS), UCLA Activity and Satisfaction Score, and the Euro-QoL 5-dimension (EQ-5D-5L) index and visual analogue scale (EQ-VAS) health status. Results Patients (n = 176) were 61.2 +/- 8.3 years of age, BMI 44.9 +/- 6.5 kg/m2, and were predominantly female (n = 118, 66.7%). Mean follow-up was 59.2 +/- 17.1 months. There were two total revisions at 6- and 57-months post-operative, respectively, and the 5-year survival estimate was 98.3% (95% confidence interval: 93.0%, 99.6%). Patient satisfaction was 93.9% and the post-operative OKS, EQ-5D-5L index, and EQ-VAS were 40.2 +/- 7.9, 0.856 +/- 0.205, and 73.6 +/- 14.7, respectively. No cases of radiolucent lines were detected. Conclusions At 6 years this cementless monoblock tibial component demonstrated excellent survival without radiographic indications of aseptic loosening in a population of severely obese patients.