Tapered Modular Femoral Stems for Revision Total Hip Arthroplasty Show Excellent Mid-Term Survivorship

Introduction: Revision total hip arthroplasty (THA) can be challenging in the face of proximal femoral bone loss, catastrophic implant failure, or recurrent hip instability. Tapered modular femoral stems have shown substantial success at short follow up for aseptic revisions. The purpose of this study was to report mid-term revision THA outcomes of a tapered modular femoral stem at a tertiary referral center used to treat both aseptic as well as periprosthetic joint infections (PJIs). We specifically sought to assess: (1) revision-free implant survivorship; (2) patient-reported outcome measurements (i.e., Hip Disability and Osteoarthritis Outcome Score, Joint Replacement [HOOS JR]); (3) postoperative surgical complications and 30-day readmissions; as well as (4) radiographic outcomes. Materials and Methods: We reviewed a consecutive series of 92 patients who underwent revision THA between 2009 and 2013 with a tapered modular femoral stem. After accounting for mortality (n=7) and loss to follow up (n=13), a total of 72 implants in 66 patients who had eight years of mean follow up (range, 2 to 11) were included. PJI (46%) was the predominant preoperative indication for revision THA, followed by aseptic loosening (25%), periprosthetic fracture (18%), and symptomatic hardware (10%). Outcomes of interest included all-cause revision-free survivorship, postoperative complications, and HOOS JR, as well as SF-12 scores. Radiographically, they were evaluated for subsidence, radiolucencies, and loosening. Results: Aseptic revision-free survivorship of the femoral component was 95.8% (69 out of 72). Including septic cases, revision-free survivorship was 87.5% (63 cases), and 60 implants (83.3%) had an all-cause revision-free survivorship. For those patients who underwent septic revisions, eight out of nine remained infection free, while one underwent a resection arthroplasty. Furthermore, the cause for femoral aseptic revisions were subsidence (1.4%) and aseptic loosening (2.8%). Functional score improvements for HOOS JR, SF-12 PCS, as well as MCS were 29, 13, and 2, respectively (all p<0.001). There were eight emergency department visits (11.1%,) and six inpatient readmissions (8.3%). Additionally, two patients had dislocations (2.8%, two out of 72) not requiring revision. There were two cases of femoral subsidence and one aseptic loosening requiring revision; whereas, the rest did not demonstrate any progressive radiographic lucencies. Discussion: The eight-year mean survivorship results of the tapered modular femoral stems in revision THA demonstrated excellent results. Our series found improved outcome scores and relatively low postoperative complications, which indicate a favorable implant survivorship profile for revision THA. Conclusion: These results serve to inform arthroplasty surgeons of expected outcomes of the modular stems when used for patients who need complex revision THA.