Mid-Term Follow Up of Newer-Generation Morphometric Wedge Stems for Total Hip Arthroplasty (THA)

Abstract

Introduction: Proximally coated, morphometric wedge femoral stems illustrated excellent survivorship and clinical outcomes at a minimum five-year postoperative follow up.

Materials and methods: We completed a retrospective review of 186 THA patients from three high-volume surgeons to assess clinical- and patient-reported outcomes five years after implantation with a cementless, proximally coated morphometric wedge femoral stem. We reviewed Gruen zones on early postoperative and mid-term radiographs for signs of osteolysis, loosening, and wear. Clinical- and patient-reported outcomes were compared with previously published two-year outcomes for these femoral stems.

Results: No progression of radiolucencies or loosening was observed radiographically when comparing minimum one-year and five-year follow up. Reactive radiodense lines were observed in 23 cases (12.64%), and 13 cases (7.14%) exhibited true radiolucencies of 1-3mm, and all remained unchanged between follow ups or were no longer present on the five-year film. Cortical hypertrophy was noted in Gruen zones 3 and/or 5 in 11 cases (6.04%). No stems were revised for mechanical loosening or for periprosthetic fracture. Nine (9) patients (4.87%) underwent revisions during the follow-up period for periprosthetic infection, femoral head and/or acetabular component revisions, and impingement requiring release and femoral head change. Average Harris Hip Scores were excellent at five years and improved slightly when compared to a two-year follow up; however, this change was not statistically significant. Health-related quality of life mental component and physical component scores were a mean of 48.45 and 43.10 at 5 years, respectively. All cause Kaplan-Meier survivorship of the femoral stem was calculated at 98.4% at an average 65.7 months post implantation. Additionally, this cohort exhibited 100% aseptic survivorship during the follow-up period.

Conclusion: Newer-generation morphometric wedge femoral stems for THA exhibit excellent radiographic stability, patient satisfaction, and clinical outcomes five years post implantation.