Abstract
1) INTRODUCTION
Acetabular fixation in cementless total hip arthroplasty (THA) relies on new technology for stability and survivorship of the implant. A highly porous 3D titanium coating was developed with a biologically inspired pore structure to improve initial friction fixation with mechanical stability and long term biological fixation. Ongoing research is investigating potential radiographic phenomenons these coatings produce, resulting in the presence of lucent lines. The purpose of this study was to evaluate clinical and radiographic outcomes of a 3D highly porous-coated titanium acetabular shell.
2) METHODS
One hundred and sixty-two cases as part of a non-randomized, post-market, multicenter study received a primary cementless THA. Clinical outcomes including the Harris Hip Score (HHS), Lower Extremity Activity Scale (LEAS), Short Form 12 (SF12), and EuroQol 5D Score (EQ-5D) were collected preoperatively and at six weeks, one year postoperative. Additionally, radiographs, radiographic parameters and techniques were analyzed for institutional differences.
3) RESULTS
Significant postoperative improvements were seen in pain, function and quality of life outcomes through one year. The HHS improved significantly (p< 0.0001) by 28.9 points at six weeks and 41.7 points at one year postoperative (Figure 1), with 53.4% of patients scoring Excellent or Good at six weeks and 87.5% at one year (Figure 2). Pain and physical functioning reported by the SF-12, EQ-5D and LEAS showed further clinical improvements at one year (Figure 1).
Radiographically, 9.5% of cases reviewed displayed ‘radiolucent lines’ of less than 2mm in all three acetabular zones at six weeks. These cases only displayed radiolucent lines in one zone at the one year timepoint (Figure 3). Patients with radiolucent lines reported an average HHS score of 77 and 96 at six weeks and one year, respectively, with no radiographic failures or any revisions to date. The radiographic parameters and techniques were collected to analyze differences between the imaging techniques between institutions. Institutions utilizing digital radiography with an automatic exposure control technique, had cases where ‘radiolucent lines’ were present. One institution utilizing computed radiography with a manual technique did not have any cases display ‘radiolucent lines’.
4) DISCUSSION and CONCLUSION
Despite the appearance of transient radiographic lucent lines, patients in this study have shown positive clinical outcomes and initial stability through one year postoperative. These results do not correlate with the presence of radiolucent lines. Additionally, there may be a correlation between the imaging techniques and the presence of ‘radiolucent lines.’ As this device is still widely implanted using the same surgical technique, longer follow-up is needed to confirm a true biologic fixation and survivorship of the shell.
