Early catastrophic acetabular failure in Furlong total hip replacements.

The use of uncemented hip arthroplasty prostheses with ceramic articulations are popular, especially in the young, because of a perceived reduction in wear. We highlight a complication of ceramic on polyethylene articulating couples not previously described in the Furlong replacement. Despite widespread metalosis and particulate debris, osteolysis was not initially seen. The contamination compromised subsequent revision.

The correlation between immediate radiolucent lines and early implant migration in cemented acetabular components.

Periacetabular radiolucent lines (RLLs) on postoperative radiographs have been associated with early loosening of the acetabular component. It has also been shown that excessive migration of an implant corresponds to an increased incidence of later clinical failure. This study relates RLLs on anterior-posterior hip radiographs taken 10 days and 6 months postoperatively to implant migration detected by roentgen stereophotogrammetric analysis. We have shown that RLLs in DeLee and Charnley zone III in the first week postoperatively as well as at 6 months are positively and significantly (P < .05) associated with migration detected by roentgen stereophotogrammetric analysis. No significant association was found for zone I or II at either 10 days or at 6 months. Considering the limitations in observing RLLs, their presence in zone III appears to reflect on the mechanical stability of the acetabular cup from the beginning. This indicates that zone III, which represents the inferomedial aspect of the acetabulum, might have to receive special attention when preparing the acetabulum and implanting the acetabular cup.

Insertion of tantalum beads in RSA of the hip: variations in incidence of extra-osseous beads with insertion site.

Radiostereometric analysis (RSA) is a technique that can be used to measure the in-vivo micro-motion of the components of hip arthroplasty. It requires the insertion of tantalum beads into the bone permitting analysis of the radiographs. Extra-osseous beads reduce the usable bead pattern and previous studies have reported their incidence in the proximal femur as between 11% and 13% of all inserted beads. We reviewed the relative incidence of extra-osseous beads by examining 1038 radiographs of 97 patients who were part of an ongoing RSA hip study. Extra-osseous beads were seen in 44% of our patients with most having a single extra-osseous bead. The relative incidence of extra-osseous beads was 2% and 6% in the femur and pelvis, respectively. We observed a reduction in the incidence of the femoral beads with time, but not of the pelvis, which suggests that experience in the insertion technique improves the insertion rates at least of the femur. Our findings indicate that the incidence of extra-osseous beads is lower than previously reported. However, care should be taken in the design of studies to ensure that an adequate number of beads are placed in locations which are both surgically achievable and technically useful.