Background: To improve the long-term performance of hip prostheses, alternative bearings with metal-on-metal (MoM) and ceramic-on-ceramic (CoC) couples have been introduced. Although currently the results from the use of these bearings are in the midterm stage, there have been few comparative studies of these different bearings. Methods: From 2000 to 2002, 487 total hip replacements were performed with use of a BICON-PLUS acetabular cup and an SL-PLUS femoral stem (Plus Orthopedics, Rotkreuz, Switzerland, now Smith & Nephew Orthopaedics). The patients were divided into three groups according to the type of bearing that was used: an MoM group (sixty-nine prostheses), a metal-on-polyethylene (MoP) group (200 prostheses), and a CoC group (218 prostheses). Patient demographic data and data with regard to revision operations were evaluated from the hospital computer database. The mean follow-up period was 8.5 years (range, 6.9 to 10.5 years). Patient activity was assessed with use of the University of California at Los Angeles activity scale. Results: The mean patient age was sixty years at the time of the index arthroplasty in the MoM and CoC groups, and seventy-one years in the MoP group. Based on a scale of ten, the mean postoperative activity level was six in the CoC group, five in the MoM group, and four in the MoP group. Survival at ten years with regard to revision for any reason was 0.984, 0.956, and 0.879 for the MoP, CoC, and MoM groups, respectively. When revision for any reason was considered as the end point, survival of the MoM bearings was significantly worse than that of the MoP bearings (p = 0.005). Survival at ten years with regard to revision for aseptic loosening was 0.995, 0.990, and 0.894 for the MoP, CoC, and MoM groups, respectively. When revision for aseptic loosening was considered as the end point, survival of the MoM group was significantly worse than that of either the MoP group (p = 0.001) or the CoC group (p = 0.003). Conclusions: When comparing two groups of patients of similar mean age and mean activity level undergoing total hip arthroplasty with the use of alternative bearings, CoC bearings had better survival than did MoM bearings at the ten-year follow-up; the difference was significant when revision for aseptic loosening was defined as a failure. However, neither the CoC nor the MoM alternative bearings provided improved midterm results when compared with the results of the conventional MoP bearings. For older, less active patients, traditional metal-on-polyethylene bearings are the appropriate choice. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background and purpose — Despite 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 methods — In 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. Results — General 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). Interpretation — Some associations were found between the THRs’ features, especially a positive association between metal-on-metal bearings, and specific cancers.

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.

Purpose: The purpose of this study was to compare the results of revision total hip arthroplasty after fracture of primary ceramic components using different type of revision bearing surfaces. Methods: We analysed the results of 16 patients with a follow-up more than 3 years after first revision. 6 were revised to ceramic-on-ceramic (CoC) bearing, 9 to metal-on-polyethylene (MoP) and 1 to ceramic-on-cross-linked polyethylene (CoXLP) bearing. Results: The mean follow-up was 87 months. Patients with revision to CoC had higher Harris Hip Score (HHS) of 89 points in comparison to the patients with revision to MoP with 84 points. Radiographic examinations revealed visible eccentric polyethylene wear with osteolysis in 3 out of 9 patients revised to MoP. There were no detrimental x-ray changes in patients revised to CoC components. Conclusions: We consider CoC as the best option at revision operation for ceramic component fracture.

Background and Objectives: Increased revision rate of dual-modular (DM) femoral stems in primary total hip arthroplasty (THA) because of modular-neck breakage and adverse local tissue reactions (ALTRs) to additional junction damage products is well established and some designs have been recalled from the market. However, some long-term studies of specific DM stems did not confirm the inferiority of these stems compared to standard single-modular (SM) stems, and a head-to-head comparison THA is missing. The objectives of this multicentre study were to determine the survivorship and complication rates of a common DM stem design compared to a similar SM stem. Materials and Methods: In a time frame from January 2012 to November 2015, a cohort of 807 patients (882 hips) consecutively underwent primary cementless THAs at two orthopaedic centres. 377 hips were treated with a Zweimüller-type DM stem THA system and 505 hips with a similar SM stem THA system, both including a modern press-fit acetabulum. Kaplan-Meier survivorship and complication rates were compared between both groups in a median follow-up of 9.0 years (maximum, 9.9 years). Results: The 9-year survivorship of the DM stem THA system (92.6%, 95% CI 89.9–95.3) was significantly lower than that of the SM stem THA system (97.0%, 95% CI 95.2–98.8). There were no differences in revision rates for septic loosening, dislocation, and periprosthetic fractures between the two groups. One ceramic inlay and one Ti-alloy modular neck breakage occurred in the DM stem THA system group, but the main reason for revision in this group was aseptic loosening of components. Conclusions: The survivorship of the DM stem THA system was lower than the similar SM stem THA system in a comparable clinical environment with long-term follow-up. Our results confirmed that no rationale for stem modularity exists in primary THAs.