Background: Second-generation metal-on-metal total hip replacements were introduced in the early 1990s with the aim of eliminating polyethylene wear and the resulting complications of osteolysis and aseptic loosening. The goal of the present study was to evaluate the intermediate-term results in a series of patients who were managed with one of these implants. Methods: Between 1994 and 2002, we performed 640 total hip replacements in 591 patients with use of a Bicon-Plus cementless threaded cup with a polyethylene liner housing a metal inlay made of Sikomet low-carbon cobalt-chromium-molybdenum alloy that articulates with a Sikomet metal femoral head. Clinical and radiographic evaluation was performed retrospectively at a mean of 7.1 years postoperatively. Histologic analysis was performed on specimens retrieved from seventeen hips that were revised, and wear measurements were made for six hips that were revised. Results: Thirty-four hips (thirty-four patients) were revised because of infection (six hips), aseptic loosening (twenty-three hips), pain without loosening (two hips), or other reasons (three hips). The survival rate of the prosthesis as a whole at ten years, with revision for any reason as the end point, was 0.91 (95% confidence interval, 0.88 to 0.95). The survival rate of the cup was 0.94 (95% confidence interval, 0.90 to 0.97), and that of the stem was 0.96 (95% confidence interval, 0.94 to 0.98). Linear or expansile osteolysis, or both, was observed on the radiographs of sixteen (64%) of the twenty-five hips that were revised because of aseptic loosening and/or pain. Histological analysis of pericapsular tissue was performed for seventeen of the twenty-five hips that were revised because of aseptic loosening and/or pain. Thirteen of these seventeen hips demonstrated a hypersensitivity-like reaction with aseptic inflammatory changes accompanied by moderate to extensive diffuse and perivascular infiltration of lymphocytes. In the six retrieved specimens that were subjected to wear analysis, the main wear mode was abrasive wear. The mean cumulative linear wear for the bearing was 31.3 μm, and the mean annual wear rate was 6.3 μm/yr. The mean clearance was 87.6 μm. Conclusions: After a mean duration of follow-up of seven years, aseptic loosening was the major reason for failure of Sikomet metal-on-metal prostheses. The histological findings and the prevalence of osteolysis suggest the possibility of a hypersensitivity-like immunological response to wear particles. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Streptococci are not an infrequent cause of periprosthetic joint infection (PJI). Management by debridement, antibiotics, and implant retention (DAIR) is thought to produce a good prognosis, but little is known about the real likelihood of success. A retrospective, observational, multicenter, international study was performed during 2003–2012. Eligible patients had a streptococcal PJI that was managed with DAIR. The primary endpoint was failure, defined as death related to infection, relapse/persistence of infection, or the need for salvage therapy. Overall, 462 cases were included (median age 72 years, 50% men). The most frequent species was Streptococcus agalactiae (34%), and 52% of all cases were hematogenous. Antibiotic treatment was primarily using β-lactams, and 37% of patients received rifampin. Outcomes were evaluable in 444 patients: failure occurred in 187 (42.1%; 95% confidence interval, 37.5%–46.7%) after a median of 62 days from debridement; patients without failure were followed up for a median of 802 days. Independent predictors (hazard ratios) of failure were rheumatoid arthritis (2.36), late post-surgical infection (2.20), and bacteremia (1.69). Independent predictors of success were exchange of removable components (0.60), early use of rifampin (0.98 per day of treatment within the first 30 days), and long treatments (≥21 days) with β-lactams, either as monotherapy (0.48) or in combination with rifampin (0.34). This is the largest series to our knowledge of streptococcal PJI managed by DAIR, showing a worse prognosis than previously reported. The beneficial effects of exchanging the removable components and of β-lactams are confirmed and maybe also a potential benefit from adding rifampin.

We have prospectively studied the outcome of infections associated with implants which were retained and treated using a standardised antimicrobial protocol. Over a period of four years, we studied 24 consecutive patients who had symptoms of infection for less than one year, a stable implant, no sinus tract and a known pathogen which was susceptible to recommended antimicrobial agents. The infections involved hip prostheses (14), knee prostheses (5), an internal fixation device (4), and an ankle prosthesis (1). Twenty patients had a successful outcome at a median follow-up of 3.7 years (1.8 to 4.7); four had failure of the implant after a median follow-up of 1.2 years (0.3 to 2.5). The probability of survival without failure of treatment was 96% at one year (95% confidence interval (CI) 88 to 100), 92% at two years (95% CI 80 to 100) and 86% at three years (95% CI 72 to 100). Patients with a short-term infection but with a stable implant, no sinus tract and a known pathogen may be successfully treated by retention of the implant and the use of a standardised regimen of antimicrobial treatment.

Prosthetic joint infection (PJI) is a severe complication that occurs in 0.5–3% of arthroplasties [ 1 x 1 Pulido, L, Ghanem, E, Joshi, A, Purtill, JJ, and Parvizi, J. Periprosthetic joint infection: the incidence, timing, and predisposing factors. Clin Orthop Relat Res. 2008; 466: 1710–1715 Crossref | PubMed | Scopus (534) | Google Scholar See all References , 2 x 2 Soriano, A, Bori, G, García‐Ramiro, S et al. Timing of antibiotic prophylaxis for primary total knee arthroplasty performed during ischemia. Clin Infect Dis. 2008; 46: 1009–1014 Crossref | PubMed | Scopus (40) | Google Scholar See all References , 3 x 3 Yokoe, DS, Avery, TR, Platt, R, and Huang, SS. Reporting surgical site infections following total hip and knee arthroplasty: impact of limiting surveillance to the operative hospital. Clin Infect Dis. 2013; 57: 1282–1288 Crossref | PubMed | Scopus (38) | Google Scholar See all References ] and staphylococci are the most frequently isolated microorganisms [ 4 x 4 Moran, E, Byren, I, and Atkins, BL. The diagnosis and management of prosthetic joint infections. J Antimicrob Chemother. 2010; 65: iii45–iii54 Crossref | PubMed | Scopus (98) | Google Scholar See all References 4 ]. Coagulase-negative staphylococci account for 30–41% and Staphylococcus aureus for 12–39%. Gram-negative organisms are less common than Gram-positive, causing around 10% of cases [ 5 x 5 Peel, TN, Cheng, AC, Buising, KL, and Choong, PFM. Microbiological aetiology, epidemiology, and clinical profile of prosthetic joint infections: are current antibiotic prophylaxis guidelines effective?. Antimicrob Agents Chemother. 2012; 56: 2386–2391 Crossref | PubMed | Scopus (88) | Google Scholar See all References 5 ]. Among Gram-positive bacteria, Enterococcus sp. account for 3–10% [ 6 x 6 Berbari, EF, Osmon, DR, Duffy, MCT et al. Outcome of prosthetic joint infection in patients with rheumatoid arthritis: the impact of medical and surgical therapy in 200 episodes. Clin Infect Dis. 2006; 42: 216–223 Crossref | PubMed | Scopus (93) | Google Scholar See all References , 7 x 7 Marculescu, CE, Berbari, EF, Hanssen, AD et al. Outcome of prosthetic joint infections treated with debridement and retention of components. Clin Infect Dis. 2006; 42: 471–478 Crossref | PubMed | Scopus (273) | Google Scholar See all References , 8 x 8 Moran, E, Masters, S, Berendt, AR et al. Guiding empirical antibiotic therapy in orthopaedics: the microbiology of prosthetic joint infection managed by debridement, irrigation and prosthesis retention. J Infect. 2007; 55: 1–7 Abstract | Full Text | Full Text PDF | PubMed | Scopus (126) | Google Scholar See all References ]; however, the isolation of enterococci has been associated with a worse outcome [ 9 x 9 Soriano, A, Garcia, S, Bori, G et al. Treatment of acute post‐surgical infection of joint arthroplasty. Clin Microbiol Infect. 2006; 12: 930–933 Abstract | Full Text | Full Text PDF | PubMed | Scopus (82) | Google Scholar See all References , 10 x 10 Lora‐Tamayo, J, Euba, G, Ribera, A et al. Infected hip hemiarthroplasties and total hip arthroplasties: differential findings and prognosis. J Infect. 2013; 67: 536–544 Abstract | Full Text | Full Text PDF | PubMed | Scopus (13) | Google Scholar See all References ] probably due to the tolerance of enterococci to different classes of antibiotics. The largest case series was published by El Helou et al. [ 11 x 11 El Helou, OC, Berbari, EF, Marculescu, CE et al. Outcome of enterococcal prosthetic joint infection: is combination systemic therapy superior to monotherapy?. Clin Infect Dis. 2008; 47: 903–909 Crossref | PubMed | Scopus (34) | Google Scholar See all References 11 ] where they described 50 cases treated in one institution over 30 years; however, polymicrobial infections were excluded from the analysis and recent data suggest that PJI are frequently polymicrobial—probably due to improvements in sampling and microbiological methods.

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.