Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Biomedical Engineering
Collaborative Specialization
Musculoskeletal Health Research
Supervisor
Teeter, Matthew G.
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.
Summary for Lay Audience
Osteoarthritis is a disease that affects the main joints in the human body and is a leading cause of disability worldwide. Patients with hip osteoarthritis commonly have pain and mobility issues that significantly impact their daily life. When the condition becomes severe, the only option for patients is to have a hip replacement surgery, where the damaged bone and cartilage are replaced with prosthetic implant components that mimic a healthy hip joint. However, a possible complication after this surgery is the loosening of the implant components, potentially leading to a second, more complex and costly surgery.
This thesis aimed to compare how different hip replacement techniques and implant designs affect the stability of the implant in the bone. Detecting early movement, or migration, of the implant is important as it may signal the risk of the implant loosening over time. A special x-ray imaging technique called radiostereometric analysis (RSA) was used to accurately measure how the stem and cup implant components moved within the bone after surgery. Also, this thesis explored a newer imaging technique called CT-based RSA (CT-RSA) that is more accessible for clinical use compared to RSA.
Patients participating in this study were divided into groups based on the design of stem implant they received, and the surgical technique that was used. This thesis found that stem design did not significantly affect movement in one of the surgical groups, but in the other, a collared stem design helped reduce movement and had better initial stability. This thesis also discovered that using a single screw for the cup implant led to more movement compared to using no screws or two screws. Lastly, findings of this thesis are supportive of the use of CT-RSA for implant movement analysis to assess stem fixation, with more precision than RSA.
The study concludes that the way a hip replacement is performed, and the design of the implant can greatly affect the implant's early stability. The CT-RSA technique emerged as a promising tool for monitoring implants over time, offering a new way to help predict and diagnose complications like implant loosening.
Recommended Citation
Polus, Jennifer Sabah, "Comprehensive Assessment of Implant Movement Following Total Hip Arthroplasty: Analysis of Surgical Approach, Implant System, and Imaging Techniques" (2024). Electronic Thesis and Dissertation Repository. 10050.
https://ir.lib.uwo.ca/etd/10050
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