Aims Metal-on-Metal (MoM) implants have been widely used since the early years of total hip arthroplasty (THA) development. Several clinical trials have shown promising outcomes compared with other implants. However, long-term clinical assessments are lacking. The aim of this prospective cohort study was to compare functional outcome scores and revision rates between MoM and non-MoM THA at the long-term follow-up.
Materials and Methods A cohort of 67 patients (67 hips) who underwent a primary THA with MoM and non-MoM from 2008 to 2010 was enrolled the study. At the patient’s clinic visit after at least 8 years of the surgery, we collected the required data to estimate the Harris Hip Score (HHS).
Results A total of 60 patients (MoM=22, non-MoM=38) were included in the final analysis. At the average follow-up time of 10.8 years, two of twenty-two MoM patients require revision surgery, while none of the non-MoM patients requires revision (P=0.071). The survival rates of MoM implants were similar to non-MoM implants (P=0.955). The mean HHS was significantly higher for non-MoM implants (91.66±9.08) compared to the MoM implants (81.64±20.05, P=0.036).
Conclusion HHS of MoM implants was lower than non-MoM implants at the long-term follow-up, neither of the Range of Motion (ROM) and absence of deformity. In addition, the revision rate in the MoM group was higher than the non-MoM group. Long-term follow-up is essential to evaluate the safety and functional outcome of the implants and optimize the care of patients with MoM implants.
Keywords: Metal-on-metal; Total hip arthroplasty; Periprosthetic joint infection
Abbreviations: Mom: Metal-on-Metal; THA: Total Hip Arthroplasty; ROM: Range of Motion; HHS: Harris Hip Score; Coc: Ceramics-on-Ceramics; Cop: Ceramics-on-Polyethylene; Mop: Metal-on-Polyethylene; MRI: Magnetic Resonance Imaging; OA: Osteoarthritis; FNF: Femoral Neck Fracture; ANFH: Avascular Necrosis of Femoral Head; DDH: Developmental Dysplasia of The Hip; PJI: Periprosthetic Joint Infection; LOS: Length of Stay