Conversion of Hip Hemiarthroplasty to Total Hip Arthroplasty Utilizing a Dual-Mobility Construct Compared With Large
Brian P Chalmers1, Kevin I Perry1, Arlen D Hanssen1
1Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota.
Background:
Conversion of hemiarthroplasty to total hip arthroplasty (THA) has a historically high, up to 20%, postoperative dislocation rate. As such, dual-mobility (DM) constructs are an attractive option to mitigate this complication. We analyzed survivorship free of revision, complications, and clinical outcomes of hemiarthroplasties conversion to THAs utilizing DM constructs compared with large femoral heads (≥36 mm).
Methods:
Conversion of 16 hemiarthroplasties to THAs with a specific DM construct compared with 13 conversions utilizing large femoral heads (≥36 mm) from 2011 to 2014 were reviewed. Mean age at conversion in the DM group was 75 years (range, 57-93 years); 75% were female. Significantly more patients with a dislocated hemiarthroplasty were converted to DM constructs compared to large femoral heads (44% vs 0%; P = .01). Mean follow-up was 3 years.
Results:
Survivorship free of revision was 100% in the DM group compared with 92% in the large femoral head cohort at 2 years (P = .7). One (8%) patient converted to a large femoral head underwent revision to a constrained liner for recurrent dislocations while no patients experienced a postoperative dislocation in the DM group (P = .4). Harris Hip Scores improved from 54 to 82 (P < .01) in the DM group, and from 52 to 86 in the large femoral head group (P < .01).
Conclusion:
Larger effective femoral heads used during conversion of hemiarthroplasties to THAs resulted in high survivorship free of revision, minimal complications, and excellent clinical outcomes at short-term follow-up. In patients at highest risk for postoperative dislocation, including those with dislocating hemiarthroplasties, DM constructs resulted in no postoperative dislocations.
