Mid-term Clinical and Radiographic Outcomes of the Actis Total Hip System: A Retrospective Study

Introduction
Implant technology for total hip arthroplasty (THA) was developed to improve hip function and patient satisfaction. Actis (DePuy Synthes, Warsaw, IN, USA) is a short fit-and-fill titanium stem, with a medial-collared and triple-taper (MCTT) geometry, that is fully coated with hydroxyapatite (HA). We evaluated the radiographic and clinical outcomes of the Actis Total Hip System during a mean follow-up of five years.
Patients and methods
We retrospectively analyzed data from 80 patients (14 male and 66 female, mean age: 65 ± 8.4 years) who underwent primary THA using Actis stems (anterolateral approach, 60 hips; posterior approach, 20 hips). Radiographs were obtained postoperatively and at the time of the final examination. Radiographic assessments included the alignment of the femoral stem, spot welds, stress shielding, cortical hypertrophy, subsidence (>2 mm), radiolucent line, pedestal formation, Dorr type, canal fill ratio (CFR), and stem fixation. Clinical evaluation included the Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ) and Harris Hip Score (HHS).
Results
The mean follow-up period was 64.0 ± 6.0 months. No significant differences were observed in the alignment of the femoral components between approaches. Of the 80 hips, 53 (66.3%) showed radiographic signs of stem osseointegration, predominantly in the mid-distal region of the stem at the final follow-up. Multiple logistic regression analysis revealed that younger age and a higher CFR (20 mm proximal to the lesser trochanter) were associated with the presence of spot welds. Mild stress shielding occurred in 25 hips (31.3%), and no patient experienced severe stress shielding. All stems were fixed by bone on growth. The JHEQ and HHS significantly improved at the final assessment.
Conclusion
At the five-year follow-up, patients who received the Actis Total Hip System during THA had good radiographic and clinical outcomes.