Is There a Benefit to Modularity for Femoral Revisions When Using a Splined, Tapered Titanium Stem?

Abstract Background Proposed benefits of modularity for femoral revisions in total hip arthroplasty (THA) include more precise biomechanical restoration, but this has not been proven with use of a splined, tapered design. This study’s purpose was to compare (1) complication rates (2) functional outcomes, and (3) subsidence, offset, and leg length discrepancy with the use of modular versus monoblock splined, tapered titanium stems in revision THA. Methods We retrospectively reviewed 145 femoral revisions with minimum 2-year follow-up (mean, 5.12 years; range, 2 to 17.3 years). Patients receiving a modular (67) or monoblock (78) splined, tapered titanium stem for femoral revision were included. Results There were no statistically significant differences in rates of reoperation (22.3% vs. 17.9%; P=0.7), intra-operative fracture (9.0% vs. 3.8%; P=0.3), post-operative fracture (3.0% vs. 1.3%; P=0.5), dislocation (11.9% vs. 5.1%; P=0.23), or aseptic loosening (4.5% vs. 6.4%; P=0.7) between the modular and monoblock cohorts, respectively. There similar results regarding subsidence >5mm (10.4% vs. 12.8%, P = 0.22), LLD >1cm (35.8% vs. 38.5%, P=0.74), restoration of hip offset (-5.88 + 10.1mm vs. -5.07 + 12.2mm; P=0.67), and Harris Hip Score (70.7 + 17.9 versus 73.9 + 19.7; P=0.36) between groups. Multivariate regression showed no differences in complications (P=0.44) or reoperations (P=0.20) between groups. Conclusion Modular and monoblock splined, tapered titanium stems demonstrated comparable complication rates, functional outcomes, and radiographic parameters for femoral revisions. However, a limited number of patients with Grade IIIB or IV femoral bone loss received a monoblock stem. Future investigations are required to determine if modularity is beneficial for more complex femoral defects.