Conversion of metal-on-metal THA to dual mobility implant may yield lower complication rate
Published results showed failed monoblock metal-on-metal total hip arthroplasty may benefit from limited revision with conversion to a dual mobility implant, which may yield lower complication rates compared with formal revision.
Researchers reviewed 143 revisions of monoblock metal-on-metal (MoM) THAs, of which 29 of were revised to a dual mobility construct and 114 were complete revisions of the acetabular component. Researchers investigated components used, acetabular cup position, radiographic outcomes, serum metal ion levels and the hip disability and osteoarthritis outcome score short-form (HOOS Jr) clinical outcome scores.
At 3.9-year follow-up, results showed 6.9% of patients in the dual mobility cohort underwent revision for instability and periprosthetic fractures compared with 16% of patients in the formal acetabular revision group who underwent revision surgery for aseptic loosening of the acetabular component, deep infection, dislocation, acetabular fracture or delayed wound healing. Researchers also found a 20% rate of major complications among the formal acetabular revision group. Although no patients in the dual mobility cohort had radiographic signs of aseptic loosening, component migration or polyethylene wear, results showed one patient in the dual mobility group had a small posterior metadiaphyseal femur lesion that required close monitoring. Researchers found no other radiographic signs of osteolysis, no clinically significant elevations of serum metal ion levels and favorable HOOS Jr scores.
“We report here our experience of 29 patients who underwent limited revision to [dual mobility] DM of a failed monoblock MoM hip,” the authors wrote. “This DM option had nearly a five-times lower reoperation rate than complete revision of a monoblock acetabular component. Continued surveillance and longer follow-up [are] needed to demonstrate any potential wear implications of these articulations.” – by Casey Tingle
Disclosures: Colacchio reports he is on the speakers bureau for DePuy and is a paid consultant for Gerson Lehrman Group Inc. Please see the study for all other authors’ relevant financial disclosures.