Cementless Versus Cemented Total Knee Arthroplasty: Concise Midterm Results of a Prospective Randomized Controlled Trial.

BACKGROUND: We previously reported the 2-year results of a prospective randomized controlled trial of cementless versus cemented total knee arthroplasty (TKA) implants of the same design. The purpose of the present study was to provide concise results at intermediate-term follow-up. METHODS: The original study included 141 TKAs (76 performed without cement and 65 performed with cement). Since then, 8 patients died and 4 withdrew. Of the remaining 129 patients, 127 (98%) were available for analysis. Survivorship analysis was performed; Oxford Knee, Knee Society, and Forgotten Joint Scores were calculated; and radiographs reviewed. Mean follow-up was 6 years. RESULTS: The survivorship free of any revision was 100% in both groups. There were no differences between the groups in any patient-reported functional outcome measure (p = 0.2 to 0.5). However, a higher percentage of patients in the cementless TKA group were either extremely or very satisfied with their overall function (p = 0.01). Radiographically, there was no evidence of implant loosening in either group. CONCLUSIONS: At 6 years, there were no differences between cementless and cemented TKA implants of the same design in terms of survivorship, clinical, or radiographic outcomes. LEVEL OF EVIDENCE: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Cemented Versus Cementless Total Knee Arthroplasty of the Same Modern Design: A Prospective, Randomized Trial.

BACKGROUND: Highly porous surfaces promoting biologic fixation have renewed interest in cementless total knee arthroplasty (TKA), but the potential for failed biologic fixation remains. The purpose of this study was to compare the clinical outcomes of cemented and cementless versions of the same TKA design at an average of 2 years postoperatively. METHODS: This was an institutional review board-approved, prospective, randomized controlled trial of patients from 18 to 75 years of age who were undergoing a primary TKA. Patients with inflammatory arthritis, a body mass index (BMI) of >40 kg/m, infection, a neuromuscular disorder, or grossly osteoporotic bone or bone defects were excluded. Patients were randomized to receive a cemented or cementless cruciate-retaining TKA of the same design. The cementless implant has highly porous fixation surfaces. Oxford Knee, Knee Society, and Forgotten Joint Scores were collected. Patients were asked to rate the knee with the TKA as a percentage of normal. Power analysis indicated that 130 patients were necessary to demonstrate a 5-point difference in the Oxford Knee Score at 90% power. RESULTS: One hundred and forty-seven patients were enrolled, and 141 (96%) of them were analyzed at an average of 2 years postoperatively. There was no difference in age, sex, BMI, American Society of Anesthesiologists (ASA) score, or duration of follow-up (p = 0.1 to 0.9). There was also no difference in the change in the hemoglobin level from the preoperative measurement to postoperative day 1 between the 2 cohorts (mean and standard deviation, -2.6 ± 1.4 g/dL compared with -2.5 ± 0.9 g/dL, p = 0.5), but the total operative time was decreased in the cementless cohort (82.1 ± 16.6 compared with 93.7 ± 16.7 minutes, p = 0.001). There were no differences in any clinical outcome measure at 4 to 6 weeks, 1 year, or an average of 2 years postoperatively (p = 0.1 to 0.9) between the cemented and cementless cohorts. There was no radiographic evidence of component subsidence or loosening in either cohort. CONCLUSIONS: This study demonstrated that a recently introduced cementless TKA had results, both perioperatively and at an average of 2 years postoperatively, that were equivalent to those of its cemented predecessor, without any aseptic failures of either implant. Thus, this study justifies continued surveillance of this device to elucidate both its survivorship and if it can provide any long-term benefits. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

An evaluation of proximal femur bone density in young, active patients undergoing total hip arthroplasty at one year postoperatively.

BACKGROUND:: Prior investigations have shown a decrease in periprosthetic bone mineral density (BMD) of the calcar following total hip arthroplasty (THA). The purpose of this investigation was to study proximal femur BMD in a cohort of young, active patients following THA at 1 year postoperatively using a recently introduced stem design. METHODS:: This was a prospective, IRB-approved investigation of patients with an age <65 years, BMI <35 kg/m2, and presymptomatic UCLA score of >6 undergoing a primary THA for a diagnosis of osteoarthritis. All patients received a titanium, proximally coated, tapered cementless femoral stem (ACCOLADE II, Stryker Inc, Mahwah, NJ, USA). Dual energy X-ray absorptiometry scans were performed at 6 weeks, 6 months, and 1 year postoperatively. Bone density was analyzed for 7 traditional Gruen zones with BMD ratios calculated for change in BMD compared with the baseline. RESULTS:: 31 patients (mean age of 52.6 + 6.5 years, BMI of 27.9 + 3.9 kg/m2, and UCLA activity score of 7.3 + 1.9) were included. The mean BMD ratio decreased at the 6 months and 1 year interval in zones 1 and 2. However, the mean BMD ratio was maintained in Gruen zones 3 thru 7 with zone 7 (medial calcar) demonstrating 100% maintenance of the baseline BMD at 1 year. CONCLUSION:: This study demonstrates the maintenance of medial calcar bone density at 1 year postoperatively in young, active patients undergoing THA. Further longitudinal analysis of this stem design is necessary to elucidate the significance of this finding.

Metal Ion Levels in Young, Active Patients Receiving a Modular, Dual Mobility Total Hip Arthroplasty.

BACKGROUND: Dual mobility total hip arthroplasty (THA) components improve stability, yet use of a modular cobalt alloy acetabular liner may be associated with metal ion release. This study's purpose was to measure blood metal ion levels in young, active patients receiving a dual mobility THA prosthesis. METHODS: This is a prospective study of young, active patients undergoing primary THA. Twenty-six patients received a 22-mm cobalt alloy (n = 10) or a 28-mm ceramic (n = 16) femoral head, a modular cobalt chrome acetabular liner, with a highly cross-linked polyethylene insert (dual mobility). Seventeen control patients received a 32-mm cobalt alloy (n = 6), oxidized zirconium (n = 5), or ceramic (n = 6) femoral head and polyethylene acetabular liner (conventional). All patients received a cementless, titanium femoral stem. Blood metal ion levels (µg/L) were measured preoperatively and at 1 year postoperatively. RESULTS: No difference was present for age or body mass index (P = .5 and .9). At 1 year postoperatively, mean cobalt levels were greater in the dual mobility cohort (0.23 ± 0.39 vs 0.15 ± 0.07, P < .001). Four patients in the dual mobility cohort had a cobalt level outside the reference range (0.03-0.29), with values from 0.34 to 1.81 µg/L. One patient in the conventional cohort had a cobalt level outside the reference range with a value of 0.39 µg/L. CONCLUSION: The presence and clinical significance of increased cobalt levels in 4 patients with the use of a modular dual mobility prosthesis demonstrates the necessity of continued surveillance.

Statistical trends in the Journal of the American Medical Association and implications for training across the continuum of medical education.

BACKGROUND: Statistical training across the continuum of medical education may not have advanced at the pace of statistical reporting in the medical literature, yet a comprehensive understanding of statistical concepts most commonly presented in current research is critical to the effective practice of Evidence Based Medicine. The objective of this content analysis was to describe statistical techniques used in a leading medical journal, JAMA, across a 20-year period, with a focus on implications for medical education. METHODS AND FINDINGS: Two issues of JAMA published each month in 1990, 2000, and 2010 were randomly selected; from these, 361 articles were reviewed. Primary focus, study design, and statistical components were abstracted and examined by year of publication. The number of published RCTs and cohort studies differed significantly across years of interest, with an increasing trend of publication. The most commonly reported statistics over the 20-year period of interest included measures of morbidity and mortality, descriptive statistics, and epidemiologic outcomes. However, between 1990 and 2010, there was an increase in reporting of more advanced methods, such as multivariable regression, multilevel modeling, survival analysis, and sensitivity analysis. While this study is limited by a focus on one specific journal, a strength is that the journal examined is widely read by a range of clinical specialties and is considered a leading journal in the medical field, setting standards for published research. CONCLUSIONS: The increases in frequency and complexity of statistical reporting in the literature over the past two decades may suggest that moving beyond basic statistical concepts to a more comprehensive understanding of statistical methods is an important component of clinicians' ability to effectively read and use the medical research. These findings provide information to consider as medical schools and graduate medical education training programs review and revise their statistical training components.