Two‐year migration characteristics of a novel cementless femoral stem: a radiostereometric analysis and clinical outcomes study

Abstract

Background Radiostereometric analysis (RSA) is an established high precision tool enabling us to detect early implant migration in total hip arthroplasty. The aim of this study is to present the RSA and clinical results of a new cementless hip stem and to compare those with established benchmarks. Methods A total of 45 patients (46 hips) undergoing total hip arthroplasty were available for full radiographic and clinical assessment at 2 years post‐operatively. Mean patient age was 69 (range 43–85) years and mean body mass index was 29 (range 21–38) kg/m2. RSA was undertaken at day 1, 6 weeks, 6 months and 1 and 2 years post‐operatively. Oxford hip score and EQ‐5D‐5L scores were recorded preoperatively and at the same other time points. Results were compared to published data of established implants. Results At 2 years, mean subsidence and retroversion were 0.61 mm (standard deviation 0.7 mm, range −0.19 to 3.06 mm) and 0.44° (standard deviation 0.81°, range 0.98 to 3.29°), respectively. Stem migration occurred primarily in the first 6 weeks with no detectable subsidence or rotation at 6 months or 2 years. Mean Oxford hip score and EQ‐5D‐5L improved from 18.6 to 44.7, and 69 to 86, respectively. There was one cup‐only revision and no revisions for stem loosening. Conclusion RSA serves as an accurate measure of femoral stem stability early in the post‐operative period. Our data confirm that stability occurs as early as 6 weeks and is sustained at 2 years. The Paragon stem demonstrates stability parameters at 2 years that exceed other established benchmark implants.

A Novel Nanostructured Surface on Titanium Implants Increases Osseointegration in a Sheep Model

“…For clinical relevance, we compared the novel implant surface with PCHA, which is a gold-standard implant surface with a successful clinical history [6, 28], with the null hypothesis that the AHT surface would show no difference in the defined primary and secondary outcome measures when compared with this gold-standard uncemented surface. Widely used uncemented prosthesis surfaces include hydroxyapatite only, plasma-sprayed, commercially pure titanium (CP Ti), a mixture of these two (PCHA; as used in this study), and sintered beads [54].…”

“…2). Porous commercially pure titanium coated with hydroxyapatite (PCHA) is a common surface for uncemented titanium orthopaedic implants [28]. The sheep long bone model has been used extensively for similar evaluations of osseointegration [11-13, 18, 19, 26, 84, 87].…”