Comprehensive Assessment of Implant Movement Following Total Hip Arthroplasty: Analysis of Surgical Approach, Implant System, and Imaging Techniques
Abstract
Total hip arthroplasty (THA) is a definitive treatment for end-stage hip osteoarthritis, significantly alleviating pain, restoring function, and improving quality of life. However, the rise in THA procedures is matched by an increase in revision surgeries. Aseptic loosening, the failure of the implant to maintain fixation with the bone, is one of the most common causes of revision THA. This thesis investigates in vivo implant migration as a predictive marker for aseptic loosening, comparing different surgical techniques and implant designs through radiographic imaging techniques.
This thesis utilized the gold-standard radiostereometric analysis (RSA) and explored computed tomography-based RSA (CT-RSA) for implant migration tracking. The objectives of this thesis were to compare early implant component migration between different surgical approaches and implant designs, and to explore the utility of CT-RSA as a comparable alternative to RSA for implant migration analysis.
To accomplish these objectives, patients were prospectively randomized to collared or collarless stem designs and underwent either direct lateral (DL) or direct anterior (DA) surgery, with the DA group also receiving supplemental screw fixation for the acetabular cup. RSA imaging was performed multiple times from the day of surgery to two-years postoperation to assess femoral stem and cup migration between patient groups. At five-years postoperation, inducible displacement of the femoral stem was analyzed and compared between CT-RSA and RSA.
This thesis found that stem design had no impact on migration in the DL group, but the collared stem significantly mitigated migration in the DA group. The DA group experienced more early migration than the DL group for both stem designs, most of which occurred in the first two weeks. Further, this thesis found single-screw cup fixation led to more migration compared to no-screw or two-screw methods. Finally, CT-RSA demonstrated lower magnitude of inducible displacement with higher precision than RSA, supporting its clinical utility without the need for bone markers or specialized equipment.
Ultimately, findings indicate that early implant stability is significantly influenced by surgical techniques and implant designs, and that CT-RSA presents as a valuable alternative for implant migration tracking, with the potential to aid in diagnosing aseptic loosening of orthopaedic implants.