Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background Femoral stems with bimodular (head-neck as well as neck-body) junctions were designed to help surgeons address patients’ hip anatomy individually. However, arthroplasty registers have reported higher revision rates in stems with bimodular junctions than in stems with modularity limited to the head-neck trunnion. However, to our knowledge, no epidemiologic study has identified patient-specific risk factors for modular femoral neck fractures, and some stems using these designs still are produced and marketed. Questions/purposes The purposes of this study were (1) to establish the survival rate free from aseptic loosening of one widely used bimodular THA design; (2) to define the proportion of patients who experienced a fracture of the stem’s modular femoral neck; and (3) to determine factors associated with neck fracture. Methods In this retrospective, nationwide, multicenter study, we reviewed 2767 bimodular Profemur® Z stems from four hospitals in Slovenia with a mean followup of 8 years (range, 3 days to 15 years). Between 2002 and 2015, the four participating hospitals performed 26,132 primary THAs; this implant was used in 2767 of them (11%). The general indications for using this implant were primary osteoarthritis (OA) in 2198 (79%) hips and other indications in 569 (21%) hips. We followed patients from the date of the index operation to the date of death, date of revision, or the end of followup on March 1, 2018. We believe that all revisions would be captured in our sample, except for patients who may have emigrated outside the country, but the proportion of people immigrating to Slovenia is higher than the proportion of those emigrating from it; however, no formal accounting for loss to followup is possible in a study of this design. There were 1438 (52%) stems implanted in female and 1329 (48%) in male patients, respectively. A titanium alloy neck was used in 2489 hips (90%) and a cobalt-chromium neck in 278 (10%) hips. The mean body mass index (BMI) at the time of operation was 29 kg/m2 (SD ± 5 kg/m2). We used Kaplan-Meier analysis to establish survival rates, and we performed a chart review to determine the proportion of patients who experienced femoral neck fractures. A binary logistic regression model that controlled for the potential confounding variables of age, sex, BMI, time since implantation, type of bearing, diagnosis, hospital, neck length, and neck material was used to analyze neck fractures. Results There were 55 (2%) aseptic stem revisions. Survival rate free from aseptic loosening at 12 years was 97% (95% confidence interval [CI] ± 1%). Fracture of the modular neck occurred in 23 patients (0.83%) with a mean BMI of 29 kg/m2 (SD ± 4 kg/m2.) Twenty patients with neck fractures were males and 19 of 23 fractured necks were long. Time since implantation (odds ratio [OR], 0.55; 95% CI 0.46-0.66; p < 0.001), a long neck (OR, 6.77; 95% CI, 2.1-22.2; p = 0.002), a cobalt-chromium alloy neck (OR, 5.7; 95% CI, 1.6-21.1; p = 0.008), younger age (OR, 0.91; 95% CI, 0.86-0.96; p < 0.001), and male sex (OR, 3.98; 95% CI, 1.04-14.55; p = 0.043) were factors associated with neck fracture. Conclusions The loosening and neck fracture rates of the Profemur® Z stem were lower than in some of previously published series. However, the use of modular femoral necks in primary THA increases the risk for neck fracture, particularly in young male patients with cobalt-chromium long femoral necks. The bimodular stem we analyzed fractured unacceptably often, especially in younger male patients. For most patients, the risks of using this device outweigh the benefits, and several dozen patients had revisions and complications they would not have had if a different stem had been used. Level of Evidence Level III, therapeutic study.

No abstract

We consider CoC as the best option at revision operation for ceramic component fracture.

A small but statistically significant difference was observed in the pH of synovial fluid between natural joints with degenerative diseases and joints treated with metal replacements. Based on the increased metal levels we expected the value of pH to be lower, but the influence of metal ions is counteracted by the buffering capacity of human body. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2507-2515, 2017.

Background: Mixing and matching components from different manufacturers in total hip arthroplasty is a frequently used off-label praxis. The clinical consequences of this procedure have not been studied in detail. Methods: 860 patients with matched and 1067 patients with mixed primary total hip replacement (THR) components carried out between 1 January 2002 and 31 December 2004, were selected from our Institution registry. The analysis endpoint was set at 1 January 2016. THRs with poorly performing components were excluded from study groups. Kaplan-Meier survival curves for both groups were calculated and compared using the Log-Rank test and the demographic data using the chi-square test. Correlations between demographic data and revisions were calculated using bivariate correlation. Results: 28 revisions were carried out in the matched group and 67 in the mixed group. The 14-year overall survival probability was significantly better in the former (96.0%) than in the mixed group (92.7%) ( p = 0.002). Survival, free of aseptic and septic failures, was statistically, significantly higher in the matched group ( p = 0.026 and p = 0.007, respectively). The survival of the mixed subgroup with heads and stems from the same manufacturer did not differ statistically from that of the matched group ( p = 0.079). Conclusions: In contrast to the results listed in the National Joint Registry and the New Zealand Joint Registry, the survival probability in our study was, statistically, significantly higher in total hip replacements using components of the same manufacturer. Importantly, mixing and matching the components of different manufacturers led to similar survival providing the head and the stem were from the same manufacturer.

Purpose The aim of this study is to evaluate the outcome of the cementless SL-Plus stem in worldwide arthroplasty register datasets. Methods A structured analysis was conducted the registered data about the SL-Plus stem manufactured by Smith&Nephew including published data from Australia as well as previously unpublished datasets from the Registers of Lombardia, Italy and Valdoltra, Slovenia. A total of 75% of the data analysed had not been published so far. The primary outcome measure was the revision rate, calculated in revisions per 100 observed component years. We evaluated a total of 10,684 primary and 122 revision surgeries with an average follow-up period of four years. Results All datasets showed good and reproducible results for treatment with the SL-Plus stem. An average of 0.31 revisions per 100 observed component years had been reported, which is considerably below the worldwide average (1.29) found for total hip arthroplasty independent of the product. The results of a large centre did not essentially deviate from the revision rates in Lombardia, where the numbers of cases per department are relatively low on average.Conclusions There were no indications for product defects or relevant errors in application. The SL-Plus stem can be considered a high-quality product that ensures good results also in the hands of less experienced surgeons. Data from even young registers can substantially contribute to the assessment of implants, even with the short follow-up periods. These datasets particularly allow for valid assessment of safety issues and can therefore make an essential contribution to the solution of problems of current relevance.

Background and purposeDespite the increasing number of total hip replacements (THRs), their systemic influence is still not known. We have studied the influence of specific features of THRs—the bearing surface, the use of bone cement and the material of the stem—on the cancer incidence.Patients and methodsIn a retrospective cohort study we identified 8,343 patients with THRs performed at Valdoltra Hospital from September 1, 1997 to December 31, 2009. Patient data were linked to national cancer and population registries. The standardized incidence ratios (SIR) and Poisson regression relative risks (RR) were calculated for all and specific cancers.ResultsGeneral cancer risk in our cohort was comparable to the population risk. Comparing with population, the risk of prostate cancer was statistically significantly higher in patients with metal-on-metal bearings (SIR =1.35); with metal-on-polyethylene bearings (SIR =1.30), with non-cemented THRs (SIR =1.40), and with titanium alloy THRs (SIR =1.41). In these last 3 groups there was a lower risk of hematopoietic tumors (SIR =0.69; 0.66 and 0.66 respectively). Risk of kidney cancer was significantly higher in the non-metal-on-metal, non-cemented, and titanium alloy groups (SIR =1.30; 1.46 and 1.41 respectively). Risk of colorectal and lung cancer was significantly lower in the investigated cohort (SIR =0.82 and 0.83, respectively). Risk for all cancers combined as well as for prostate and skin cancer, shown by Poisson analysis, was higher in the metal-on-metal group compared with non-metal-on-metal group (RR =1.56; 2.02 and 1.92, respectively).InterpretationSome associations were found between the THRs’ features, especially a positive association between metal-on-metal bearings, and specific cancers.