Long-Term Survivorship of Total Hip Arthroplasty with Highly Cross-Linked Polyethylene for Osteonecrosis.

BACKGROUND: Osteonecrosis of the hip is the underlying etiology for 3% to 12% of total hip arthroplasties (THAs). Compared with patients who undergo THA because of osteoarthritis, those who do so because of osteonecrosis typically are younger, have a greater number of underlying diagnoses, and have inferior clinical outcomes and implant survivorship. The purpose of this study was to compare the long-term implant survivorship (median follow-up, 10 years), functional outcomes, and radiographic results of contemporary THAs with a highly cross-linked polyethylene (HXLPE) liner between patients with osteonecrosis and those with osteoarthritis. METHODS: All patients who underwent primary THA with an HXLPE liner from 1999 to 2007 were identified from our institutional total joint registry. Patients with a primary diagnosis of osteonecrosis were matched 1:1, on the basis of age, sex, and body mass index (BMI), to patients with a diagnosis of osteoarthritis. This resulted in 461 hips in 413 patients with osteonecrosis matched to 461 hips in 427 patients with osteoarthritis (mean age, 59 years; 47% female; and mean BMI, 29 kg/m). Long-term implant survivorship, patient-reported outcomes, and radiographic findings were compared. In addition, a subgroup analysis of the osteonecrosis group was performed to see whether certain underlying etiologies portended poor outcomes. The median follow-up was 10 years. RESULTS: The 15-year cumulative rates of revision were 6.6% and 4.5% in the osteonecrosis and osteoarthritis groups, respectively (hazard ratio [HR] = 1.8, p = 0.09). The 15-year cumulative rates of any reoperation were 10.5% and 6.4% in the osteonecrosis and osteoarthritis groups, respectively (HR = 2.2, p = 0.008). There were no radiographic signs of component loosening or osteolysis in the entire cohort. Despite a lower median preoperative Harris hip score (HHS) for patients with osteonecrosis, both groups had marked improvements in their scores, which were similar at all time points after surgery. The cumulative rate of reoperations at 15 years was 0% for hips with radiation-induced osteonecrosis, 6.3% for those with alcohol-induced osteonecrosis, 9.0% for those with posttraumatic osteonecrosis, 12.1% for those with steroid-induced osteonecrosis, and 25% for those with idiopathic osteonecrosis. CONCLUSIONS: Contemporary THA with an HXLPE liner offers excellent long-term implant survivorship and functional outcomes for patients with osteonecrosis; however, the risk of a reoperation is higher when compared with patients with osteoarthritis. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Increased rate of bacterial colonization on PE-components in total joint arthroplasty: An evaluation through sonication.

BACKGROUND: It is currently unclear if an isolated exchange of the mobile components, in cases of periprosthetic joint infection (PJI), leads to a complete eradication of all bacteria or if residual bacteria remain attached to the retained components? OBJECTIVE: The purpose of this study was to investigate if bacteria only adhere to certain components or materials, or if they are ubiquitously distributed throughout the joint. METHODS: Twenty hundred and eighty four patients undergoing revision total hip or total knee arthroplasty surgery were included in this retrospective cohort study. Synovial fluid cultures, periprosthetic tissue cultures, histological samples and sonicate fluid cultures (SFC) from the individual endoprosthetic components were acquired. The isolated bacterial species were recorded according to their endoprosthetic component of origin. RESULTS: In 72% of all cases with multiple SFC, the cultures were concordant with all samples being either homogenously negative or showing positive bacterial growth. The polyethylene (PE) components showed a significantly higher rate of bacterial isolation than the non-mobile components. All components and materials showed bacterial colonization, however between all other components or materials were not statistically significant. CONCLUSIONS: PE-components show a higher rate of bacterial isolation than other components. If an isolated bearing exchange is performed this should be supplemented by adequate antimicrobial therapy.