Has the Use of Fixation Techniques in THA Changed in This Decade? The Uncemented Paradox Revisited.

BACKGROUND: Despite existing studies favoring cemented fixation for patients older than 75 years, a trend toward increased use of uncemented fixation has been described in a 2013 study that used arthroplasty registry data from 2006 to 2010. Updated summarized data are needed beyond 2010 to investigate contemporary trends in the usage of uncemented fixation, especially in patients older than 75 years, and to draw attention to a potential continuing conflict between trends in fixation choice and reported revision risk. Thus, healthcare policy and practice can change and surgeons can make better implant fixation choices. QUESTIONS/PURPOSES: (1) Has the percentage of primary THAs performed with uncemented fixation changed since 2010? (2) Has the percentage of primary THAs performed in patients older than 75 years performed with uncemented fixation changed since 2010? (3) After stratifying by age, which fixation strategy (cemented versus uncemented and hybrid versus uncemented) is associated with the lowest risk of revision? METHODS: National annual reports from hip arthroplasty registers were identified, and data were extracted from registers published in English or a Scandinavian language, with at least 3 years of reported data in the period from 2010 to 2017. These included Australia, Denmark, England-Wales, Finland, the Netherlands, New Zealand, Romania, Norway, Sweden, and Switzerland, which are all countries with high completeness rates. Data regarding rates of revisions (all causes) related to fixation methods and secondary to different age groups, were taken directly from the registers and no re-analysis was done. The risk estimates were presented as either hazard ratios, rate per 100 component years or as Kaplan-Meier estimates of revision. The age groups compared for Denmark were younger than 50, 50-59, 60-69,70-79, and older than 80 years, and for Australia, New Zealand, England-Wales, and Finland, they were younger than 55, 55-64, 65-74, and older than 75 years. No data were pooled across the registers. RESULTS: The current use of uncemented fixation in primary THAs varies between 24% (Sweden) and 71% (Denmark). Increasing use of uncemented fixation has been reported in Norway, Denmark, and Sweden, whereas decreasing use of uncemented fixation has been reported in England-Wales, Australia, New Zealand, and Finland. Examining the group of patients older than 75 years, we found that the use of uncemented fixation has been stable in Netherlands, Sweden, New Zealand, and England-Wales. The use of uncemented fixation is still increasing in Denmark and Australia. In Finland, the use of uncemented fixation has decreased (from 43 % to 24 %) from 2010 to 2017. When compared with uncemented fixation, the risk of revision for hips using cemented fixation was lower in patients older than 75 years for all registers surveyed, except for the oldest males in the Finnish register. In this group, no difference was found between cemented and uncemented fixation. CONCLUSION: Our findings should be used in healthcare policy as feedback on current THAs being performed so as to direct surgeons to choose the right implant fixation, especially in patients older than 75 years, thereby reducing revision risk and increasing the long-term survival of primary THAs. It appears that femoral stem fixation may be the most important revision risk factor in older patients, and future studies should examine this perspective. LEVEL OF EVIDENCE: Level III, therapeutic study.

Recurrence rates and survival in a Danish cohort with renal cell carcinoma.

INTRODUCTION: Patients with localised and locally advanced renal cancer experience about 20% recurrence during a five-year follow-up period. The aim of the present study was to report recurrence rates and survival in a Danish population with renal cancer. METHODS: Data on patients diagnosed with renal cell carcinoma (RCC) at our institute from January 2005 to December 2013 were collected retrospectively. RESULTS: Overall, 367 patients were diagnosed with RCC during the period, and 78 patients (21%) presented with metastasis. The mean follow-up period for all patients was 41 months (standard deviation = 29, 95% confidence interval: 38-44). The total recurrence rates (RRs) at one, three and five years were 4.5%, 13.5% and 22.3%, respectively. Overall survival rates in the patients who underwent surgery with localised and locally advanced disease were 96.1%, 88.2% and 78.3% for one, three and five years, respectively. The mean time to first recurrence was 26.6 months. The one-year RR was 1.2%, 5.5% and 13.8% for low, intermediate and high-risk Leibovich scores, respectively. The three-year RR was 8.3%, 14.1% and 29.6% for low, intermediate and high-risk Leibovich scores, respectively; and the five-year RR was 12.0%, 26.6% and 52.9% for low, intermediate and high-risk Leibovich scores, respectively. CONCLUSIONS: RRs after localised and locally advanced RCC was 22%. According to the risk of recurrence, we recommend a follow-up programme after nephrectomy with computed tomography every second year for low-risk patients, annually for intermediate-risk patients and every six months for high-risk patients. FUNDING: none. TRIAL REGISTRATION: none.

Osteochondral defect repair using a polyvinyl alcohol-polyacrylic acid (PVA-PAAc) hydrogel.

Poly(vinyl alcohol) (PVA) hydrogels can be candidates for articular cartilage repair due to their high water content. We synthesized a PVA-poly(acrylic acid) (PAAc) hydrogel formulation and determined its ability to function as a treatment option for condylar osteochondral (OC) defects in a New Zealand white rabbit (NZWR) model for 12 weeks and 24 weeks. In addition to hydrogel OC implants, tensile bar-shaped hydrogels were also implanted subcutaneously to evaluate changes in mechanical properties as a function of in vivo duration. There were no statistically significant differences (p > 0.05) in the water content measured in the OC hydrogel implant that was harvested after 12 weeks and 24 weeks, and non-implanted controls. There were no statistically significant differences (p > 0.05) in the break stress, strain at break or modulus of the tensile bars either between groups. Histological analysis of the OC defect, synovial capsule and fibrous tissue around the tensile bars determined hydrogel biocompatibility. Twelve-week hydrogels were found to be in situ flush with the articular cartilage; meniscal tissue demonstrated an intact surface. Twenty-four week hydrogels protruded from the defect site due to lack of integration with subchondral tissue, causing fibrillation to the meniscal surface. Condylar micro-CT scans ruled out osteolysis and bone cysts of the subchondral bone, and no PVA-PAAc hydrogel contents were found in the synovial fluid. The PVA-PAAc hydrogel was determined to be fully biocompatible, maintained its properties over time, and performed well at the 12 week time point. Physical fixation of the PVA-PAAc hydrogel to the subchondral bone is required to ensure long-term performance of hydrogel plugs for OC defect repair.

Vitamin E-diffused highly cross-linked UHMWPE particles induce less osteolysis compared to highly cross-linked virgin UHMWPE particles in vivo.

Recent in vitro findings suggest that UHMWPE wear particles containing vitamin E (VE) may have reduced biologic activity and decreased osteolytic potential. We hypothesized that particles from VE-stabilized, radiation cross-linked UHMWPE would cause less osteolysis in a murine calvarial bone model when compared to virgin gamma irradiated cross-linked UHMWPE. Groups received equal amount of particulate debris overlaying the calvarium for 10 days. Calvarial bone was examined using high resolution micro-CT and histomorphometric analyses. There was a statistically significant difference between virgin (12.2%±8%) and VE-UHMWPE (3%±1.4%) groups in regards to bone resorption (P=0.005) and inflammatory fibrous tissue overlaying the calvaria (0.48 vs. 0.20, P<0.0001). These results suggest that VE-UHMWPE particles have reduced osteolytic potential in vivo when compared to virgin UHMWPE.

A review of current fixation use and registry outcomes in total hip arthroplasty: the uncemented paradox.

BACKGROUND: The majority (86%) of THAs performed in the United States are uncemented. This may increase the revision burden if uncemented fixation is associated with a higher risk of revision than other approaches. QUESTION/PURPOSES: We sought to investigate trends for use of uncemented fixation and to analyze age-stratified risk of revision comparing cemented, hybrid, and uncemented fixation as reported by national hip arthroplasty registries. METHODS: Data were extracted from the annual reports of seven national hip arthroplasty registries; we included all national registries for which annual reports were available in English or a Scandinavian language, if the registry had a history of more than 5 years of data collection. RESULTS: Current use of uncemented fixation in primary THAs varies between 15% in Sweden and 82% in Canada. From 2006 to 2010 the registries of all countries reported overall increases in the use of uncemented fixation; Sweden reported the smallest absolute increase (from 10% to 15%), and Denmark reported the greatest absolute increase (from 47% to 68%). Looking only at the oldest age groups, use of uncemented fixation also was increasing during the period. In the oldest age group of each of the registries we surveyed (age older than 65 years for England-Wales; age older than 75 years in three registries), cemented fixation was associated with a lower risk of revision than was uncemented fixation. CONCLUSIONS: Increasing use of uncemented fixation in THA is a worldwide phenomenon. This trend is paradoxic, given that registry data, which represent nationwide THA outcomes, suggest that cemented fixation in patients older than 75 years results in the lowest risk of revision. LEVEL OF EVIDENCE: Level II, systematic review. See Guidelines for Authors for a complete description of levels of evidence.