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 and improved stability, but this has not been proven with use of a splined, tapered design. This study's purpose is to compare (1) complication rates, (2) functional outcomes, and (3) radiographic measures of subsidence, offset, and leg length discrepancy with the use of modular vs 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, 2-17.3 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 = .66), intraoperative fracture (9.0% vs 3.8%; P = .30), postoperative fracture (3.0% vs 1.3%; P = .47), dislocation (11.9% vs 5.1%; P = .23), or aseptic loosening (4.5% vs 6.4%; P = .73) between the modular and monoblock cohorts, respectively. There were similar results regarding subsidence >5 mm (10.4% vs 12.8%; P = .22), LLD >1 cm (35.8% vs 38.5%; P = .74), restoration of hip offset (-5.88 ± 10.1 mm vs -5.07 ± 12.1 mm; P = .67), and Harris Hip Score (70.7 ± 17.9 vs 73.9 ± 19.7; P = .36) between groups. Multivariate regression showed no differences in complications (P = .44) or reoperations (P = .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 whether modularity is beneficial for more complex femoral defects.

Keywords: femoral component; modular stem; monoblock stem; nonmodular stem; proximal femoral bone loss; revision total hip arthroplasty.