Early micromotion of hip implants measured with radiostereometric analysis (RSA) is a predictor for late aseptic loosening. Computed Tomography Radiostereometric Analysis (CT-RSA) can be used to determine implant micro-movements using low-dose CT scans. CT-RSA enables a non-invasive measurement of implants. We evaluated the precision of CT-RSA in measuring early stem migration. Standard marker-based RSA was used as reference. We hypothesised that CT-RSA can be used as an alternative to RSA in assessing implant micromotions. We included 31 patients undergoing Total Hip Arthroplasty (THA). Distal femoral stem migration at 1 year was measured with both RSA and CT-RSA. Comparison of the two methods was performed with paired-analysis and Bland-Altman plots. Furthermore, the inter- and intraobserver reliability of the CT-RSA method was evaluated. No statistical difference was found between RSA and CTMA measurements. The Bland-Altman plots showed good agreement between marker-based RSA and CT-RSA. The intra- and interobserver reliability of the CT-RSA method was found to be excellent (≥0.992). CT-RSA is comparable to marker-based RSA in measuring distal femoral stem migration. CTMA can be used as an alternative method to detect early implant migration.
Refobacin Bone Cement R and Palacos Overall, 75 patients were included in the study and 71 were available at two years postoperatively. Prior to surgery, they were randomized to one of the three combinations studied: Palacos cement with use of the Optivac mixing system, Refobacin with use of the Optivac system, and Refobacin with use of the Optipac system. Cemented MS30 stems and cemented Exceed acetabular components were used in all hips. Postoperative radiographs were used to assess the quality of the cement mantle according to Barrack et al, and the position and migration of the femoral stem. Harris Hip Score, Oxford Hip Score, Forgotten Joint Score, and University of California, Los Angeles Activity Scale were collected.Aims
Methods
Aims
Patients and Methods
The primary purpose of the current study was to evaluate and compare the wear properties of vitamin E-doped, highly-crosslinked PE (VEPE) and one formulation of moderately cross-linked and mechanically-annealed ultra-high molecular weight PE (ModXLPE) in patients five years after primary THA. We also sought to understand whether polyethylene wear is associated with radiographic evidence of bone resorption or with deterioration in patient-reported outcome measures (PROMs). A total of 221 patients from four international centers were recruited into a prospective RSA and clinical outcomes study. Seventy percent (76%) of patients received VEPE (vs. ModXLPE) liners, and 36% received ceramic (vs. metal) femoral heads. PROMs and radiographs were collected preoperatively and at one, two, and five years postoperatively. In addition, RSA radiographs were collected to measure PE wear. We observed similar bedding in through the one-year interval and wear through the two-year interval between the two liner types. However, there was significantly more femoral head penetration in the ModXLPE cohort compared to the VEPE cohort at the five-year follow-up (p<0.001). The only variables independently predictive of increased wear were ModXLPE (vs VEPE) liner type (β=0.22, p=0.010) and metal (vs. ceramic) femoral head type (β=0.21, p=0.013). There was no association between increased wear and radiolucency development (p=0.866) or PROMs. No patients were found to have evidence of osteolysis. At five-years postoperatively, patients treated with VEPE (vs. ModXLPE) and ceramic (vs. metal) femoral heads demonstrated decreased wear. At the longest follow-up (five years postoperatively), the wear rates for both liner groups were very low and have not led to any osteolysis or implant failures via aseptic loosening.
Osteolysis secondary to ultra-high molecular weight polyethylene (UHMWPE) wear is a leading cause of late-term implant failure via aseptic loosening in patients treated with total hip arthroplasty (THA). Radiation crosslinking of UHMWPE has been shown to decrease wear. However, the resulting polymer (crosslinked-PE) has a high free radical content. Two different methods that have been used to reduce the remaining free radicals are mechanical annealing and chemical stabilization using Vitamin E, a free radical scavenger. The primary purpose of the current study was to evaluate and compare the wear properties of vitamin E-doped crosslinked-PE (VEPE) and one formulation of mechanically annealed crosslinked-PE using radiostereometric analysis (RSA) in patients five years after primary THA. We also sought to understand the association between polyethylene wear and patient-reported outcome measures (PROMs). Three-hundred and five patients from six international centers were enrolled. Seventy-six percent were treated with highly-crosslinked (95 kGy) VEPE liners, and the rest received moderately-crosslinked (50 kGy) (ModXL), mechanically annealed liners. Data was collected prospectively at one-, two-, and five-year intervals. At the 5-year follow-up, proximal femoral head penetration into the VEPE liners (median = 0.05mm (range, −0.03–1.20)) was significantly lower than the penetration into the ModXL liners (median = 0.15mm (range, −0.22–1.04)) (p<0.001). In the VEPE cohort the median proximal penetration did not increase from one- to five-year follow-up (p=0.209). In contrast, there was a significant increase in femoral head penetration for the ModXL group (p<0.001) during that same time. Multivariable regression showed that the only variable predictive of increased wear was ModXL liner type (B=0.12, p<0.001). There were no differences in PROMs between the liner groups, and there was no correlation between polyethylene wear and PROMs for the cohort as a whole. The current study is the largest analysis of polyethylene wear at five-year follow-up using the RSA technique. We observed similar bedding in through the two-year interval between the two liner types, however, there was significantly more wear in the ModXL cohort at five-years. Currently, the wear rates for both liner groups are below the osteolysis threshold and have not led to any implant failures via aseptic loosening. Continued follow-up will provide a better understanding of the association between wear rate and clinical outcomes.
The aim of this study was to compare the incidence of aseptic
loosening after the use of a cemented acetabular component and a
Trabecular Metal (TM) acetabular component (Zimmer Inc., Warsaw,
Indiana) at acetabular revision with bone impaction grafting. A total of 42 patients were included in the study. Patients were
randomised to receive an all- polyethylene cemented acetabular component
(n = 19) or a TM component (n = 23). Radiostereometric analysis
and conventional radiographic examinations were performed regularly
up to two years post-operatively or until further revision.Aims
Patients and Methods
Comparison of accuracy and precision in measuring wear using 4 commonly used uncemented cup designs shows small differences in mean and data scatter for marker and model-based RSA. The disadvantage with conventional RSA is that implant has to be supplied with tantalum markers, which may be difficult to visualise. This problem can be resolved with model-based RSA, but it is uncertain if this method has the same precision as marker-based RSA to measure wear. We compared these methods and studied different prosthesis geometries represented by four different uncemented cup designs (Trilogy, TMT-Trabecular Metal, Zimmer, Warsaw, USA, Ringloc, Biomet, Inc., Warsaw, Indiana, and ABG, Howmedica International, Staines, UK).Summary
Introduction
