A modified frailty index predicts complication, readmission, and 30-day mortality following the revision total hip arthroplasty.

INTRODUCTION: This study aimed to develop a modified frailty index (MFI) to predict the risks of revision total hip arthroplasty (THA). METHODS: Data from the American College of Surgeons - National Surgical Quality Improvement Program were analyzed for patients who underwent revision THA from 2015 to 2020. An MFI was composed of the risk factors, including severe obesity (body mass index > 35), osteoporosis, non-independent function status prior to surgery, congestive heart failure within 30 days of surgery, hypoalbuminemia (serum albumin < 3.5), hypertension requiring medication, type 1 or type 2 diabetes, and a history of chronic obstructive pulmonary disease or pneumonia. The patients were assigned based on the MFI scores (MFI0, no risk factor; MFI1, 1-2 risk factors; MFI2, 3-4 risk factors; and MFI3, 5+ risk factors). Confidence intervals were set at 95% with a P value less than or equal to 0.05 considered statistically significant. RESULTS: A total of 17,868 patients (45% male, 55% female) were included and had an average age of 68.5 ± 11.5 years. Odds of any complication, when compared to MFI0, were 1.4 (95% CI [1.3, 1.6]) times greater for MFI1, 3.2 (95% CI [2.8, 3.6]) times greater for MFI2, and 10.8 (95% CI [5.8, 20.0]) times greater for MFI3 (P < 0.001). Odds of readmission, when compared to MFI0, were 1.4 (95% CI [1.3, 1.7]) times greater for MFI1, 2.5 (95% CI [2.1, 3.0]) times greater for MFI2, and 4.1 (95% CI [2.2, 7.8]) times greater for MFI3 (P < 0.001). CONCLUSION: Increasing MFI scores correlate with increased odds of complication and readmission in patients who have undergone revision THA. This MFI may be used to predict the risks after revision THA.

Analysis of Research Productivity of Orthopedic Surgery Residency Applicants.

Background Orthopedic surgery has become an increasingly competitive specialty. With a pass-fail Step 1, an even greater emphasis on research has been placed to allow candidates to better distinguish themselves. This study analyzes the scholarly activity of accepted orthopedic residency applicants during medical school, assessing what factors, including the novel altmetric attention score, may be associated with greater research productivity. Methods A list of orthopedic residency programs was obtained from the Electronic Residency Application Service (ERAS). A total of 688 orthopedic residents from 180 programs who matriculated in 2020 from allopathic medical schools were identified. Resident demographic information and bibliometric data (total publications, orthopedic-related publications, h-index, and altmetric score) of publications published from July 1, 2016, to September 1, 2020, were collected. Descriptive statistics were calculated. Kruskal-Wallis tests analyzed the association between medical school characteristics and research productivity using Stata® 17.0 (StataCorp LLC, College Station, Texas). Results Postgraduate-Year-3 orthopedic residents (N=688) published 2,600 articles during medical school, averaging 3.8 articles per resident. The residents from a top 25 medical school for research had publication counts, altmetric scores, and h-indices, on average, that were higher than those from non-top 25 medical schools for research. Over 150 residents had no publications, and ~10 residents had more than 30 publications. Conclusions The results illustrate that medical school research status influences the research productivity of applicants. Also, given the average number of publications, most research listed on applications are abstracts and presentations. Utilization of the altmetric score may not yet be the best way of examining research experience because orthopedic applicants do not appear to use social networks for academic research.

National trends in distribution of underrepresented minorities within United States general surgery residency programs: A longitudinal panel study.

BACKGROUND: Cultural affinity with a provider improves satisfactoriness of healthcare. We examined 2005-2019 trends in racial/ethnic diversity/inclusion within general surgery residency programs. METHODS: We triangulated 2005-2019 race/ethnicity data from Association of American Medical Colleges surveys of 4th-year medical students, the Electronic Residency Application Service, and Accreditation Council for Graduate Medical Education-affiliated general surgery residencies. Temporal trends in minority representation were tested for significance. RESULTS: Underrepresented racial/ethnic minorities in medicine (URiMs) increased among graduating MDs from 7.6% in 2005 to 11.8% in 2019 (p < 0.0001), as did their proportion among surgery residency applicants during 2005-2019 (p < 0.0001). However, proportions of URiMs among general surgery residents (≈8.5%), and of programs without URiMs (≈18.8%), stagnated. CONCLUSIONS: Growing URiM proportions among medical school graduates and surgery residency applicants did not improve URiM representation among surgery trainees nor shrink the percentage of programs without URiMs. Deeper research into motivators underlying URiMs' residency program preferences is warranted.

Movement Is Life-Optimizing Patient Access to Total Joint Arthroplasty: Diabetes Mellitus Disparities.

This is one of a series of articles that focuses on maximizing access to total joint arthroplasty by providing preoperative optimization pathways to all patients to promote the best results and minimize postoperative complications. Because of inequities in health care, an optimization process that is not equipped to support the underserved can potentially worsen disparities in the utilization of arthroplasty. A staggering 10.5% of the American population lives with diabetes mellitus. Diabetes prevalence is 17% higher in rural communities compared with urban communities. Rates of diabetes are higher in African American, Hispanic, and American Indian populations. Barriers to health care are higher in rural areas and for vulnerable communities, positioning the management of diabetes at the intersection of risk. Poor glycemic control is a predictor of periprosthetic joint infection. Optimization tools include assessing for food security, knowledge of a social safety net and community resources, patient diabetic literacy, and relationships with primary care providers to ensure continuous check-ins as well as partnering with specialty endocrine diabetic clinics. Several strategic recommendations, such as healthcare navigators and promotores (Latinx population), are made to enable and empower, such as continuous glucose monitoring, the preoperative patient to reach a safe preoperative optimization goal for their TJA surgery.

Sodium Abnormalities Are an Independent Predictor of Complications in Total Joint Arthroplasty: A Cautionary Tale!

BACKGROUND: Electrolyte levels are commonly obtained as part of the preoperative workup for total joint arthroplasty, but limited information exists on the interplay between electrolyte abnormalities and outcomes. METHODS: The National Surgical Quality Improvement Program was queried for primary, elective total hip arthroplasty and total knee arthroplasty (THA, TKA) performed between 2011 and 2017. Three patient groups were compared: normal (control), hypernatremia, and hyponatremia. The primary outcomes were length of stay (LOS) and 30-day adverse events: complications, readmissions, reoperations, and mortality. RESULTS: A total of 244,538 TKAs and 145,134 THAs were analyzed. The prevalence of hyponatremia and hypernatremia was 6.9% and 1.0%, respectively. After controlling for any baseline differences, hypernatremia was an independent predictor of ventilation >48 hours (THA, odds ratio [OR] 3.53), unplanned intubation (THA, OR 3.14), cardiac arrest (THA, OR 2.42), pneumonia (THA, OR 2.16), Clostridium difficile infection (OR 4.66 and 3.25 for THA and TKA, respectively), LOS >2 days (THA, OR 1.16), and mortality (THA, OR 4.69). Similarly, hyponatremia was an independent predictor of LOS >2 days (TKA, OR 1.21), readmission (TKA, OR 1.40), reoperation (OR 1.32 and 1.47 for THA and TKA, respectively), surgical site infections (OR 1.39 and 1.54 for THA and TKA, respectively), and transfusion (OR 1.13 and 1.20 for THA and TKA, respectively). CONCLUSION: As the focus of total joint arthroplasty continues to shift toward value-based payment models and outpatient surgery, caution should be exercised in patients with abnormal preoperative sodium levels, particularly hypernatremia, because of significantly increased risk of prolonged LOS and 30-day adverse events.

Early and Direct Rehab Transfer Leads to Significant Cost Savings and Decreased Hospital Length of Stay for Total Joint Arthroplasty in a Veteran Population.

BACKGROUND: Total joint arthroplasty is the most common elective orthopedic procedure in the Veterans Affairs hospital system. In 2019, physical medicine and rehabilitation began screening patients before surgery to select candidates for direct transfer to acute rehab after surgery. The primary outcome of this study was to demonstrate that the accelerated program was successful in decreasing inpatient costs and length of stay (LOS). The secondary outcome was to show that there was no increase in complication, reoperation, and readmission rates. METHODS: A retrospective review of total joint arthroplasty patients was conducted with three cohorts: 1) control (n = 193), 2) transfer to rehab orders on postop day #1 (n = 178), and 3) direct transfers to rehab (n = 173). To assess for demographic disparities between cohorts, multiple analysis of variance tests followed by a Bonferroni P-value correction were used. Differences between test groups regarding primary outcomes were assessed with analysis of variance tests followed by pairwise t-tests with Bonferroni P-value corrections. RESULTS: There were no significant differences between the cohort demographics or comorbidities. The mean total LOS decreased from 7.0 days in the first cohort, to 6.9 in the second, and 6.0 in the third (P = .00034). The mean decrease in cost per patient was $14,006 between cohorts 1 and 3, equating to over $5.6 million in savings annually. There was no significant change in preintervention and postintervention short-term complications (P = .295). CONCLUSIONS: Significant cost savings and decrease in total LOS was observed. In the current health care climate focused on value-based care, a similar intervention could be applied nationwide to improve Veterans Affair services.

Total Hip Arthroplasty in Black/African American Patients: an Updated Nationwide Analysis.

BACKGROUND: The purpose of this was to investigate recent trends in procedure utilization, comorbidity profiles, hospital length of stay (LOS), 30-day outcomes, and risk factors for adverse events (AEs) among Black patients undergoing total hip arthroplasty (THA). METHODS: Using the American College of Surgeons National Surgery Quality Improvement Program, we retrospectively reviewed all Black patients who underwent elective, primary THA between 2011 and 2017. Mixed effects logistic regression analyses were performed to determine the trends in the study outcomes across each individual year. Multivariate logistic regression analyses were performed to identify independent risk factors for AEs. RESULTS: A total of 11,574 Black patients were analyzed. Over the study period, there was an increase by 109% in THA procedures performed in this racial group. During the same time, there were reductions in the prevalence of anemia, dyspnea, tobacco smoking, and osteonecrosis (p < 0.001). The rates of 30-day surgical complications, readmissions, reoperations, and mortality remained unchanged. Only the rate of medical complications demonstrated improvement, driven by a decrease in the incidence of postoperative myocardial infarction (p < 0.001). There was also a significant reduction in LOS > 2 days (68 to 37%, p < 0.001). Independent risk factors for AEs were body mass index > 35, American Society of Anesthesiologists score > 2, dependent functional status, diabetes, bleeding disorders, chronic kidney disease, and osteonecrosis as the surgical indication. CONCLUSION: Between 2011 and 2017, there were improving trends in procedure utilization, comorbidity profiles, and LOS among Black patients undergoing primary THA, but the overall rates of 30-day outcomes remained unchanged. We identified a number of risk factors that may help guide preoperative optimization and patient counseling to mitigate postoperative AEs.

Where Do We Stand Today on Racial and Ethnic Health Inequities? Analysis of Primary Total Knee Arthroplasty from a 2011-2017 National Database.

BACKGROUND: The objective of this study was to present contemporary national data on the state of racial and ethnic disparities pertaining to primary total knee arthroplasty (TKA) in the USA. METHODS: The 2011-2017 National Surgical Quality Improvement Program was used to capture all patients who underwent primary TKA. The study outcomes were differences in demographic, comorbidity burden, perioperative factors, procedure utilization, hospital length of stay (LOS), and 30-day outcomes. The five major minority groups as defined by the National Institutes of Health were compared to non-Hispanic Whites. RESULTS: In total, 262,954 patient records were analyzed, with racial identification available on 230,712 patients (87.7%). White patients accounted for 72.5% of all TKA procedures. There were higher rates of diabetes, hypertension, anemia, and prolonged surgery times among racial and ethnic minorities (p < 0.001). Baseline disparities were especially pronounced among non-Hispanic Blacks/African Americans who were also like to have higher rates of tobacco smoking and CHF (p < 0.001). After controlling for baseline differences, significant disparities in outcomes persisted, especially among Blacks/African Americans and Hispanics/Latinos who had higher odds for experiencing complications and readmissions (p < 0.001). All racial and ethnic groups, except Asians, had longer LOS (p < 0.001). Asian patients had significantly lower rates of readmissions, reoperations, and overall complications (p < 0.001). CONCLUSION: Racial and ethnic disparities remain a public health challenge for patients undergoing TKA. While initiatives aimed at improving preoperative disease-burden and comorbidity profiles represent an important step, they alone are insufficient to fully account for or eliminate the disparities in TKA outcomes.

Perception of Risk: A Poll of American Association of Hip and Knee Surgeons Members.

BACKGROUND: Providers of total hip and knee replacements are being judged regarding quality/cost by payers using competition-based performance measures with poor medical and no socioeconomic risk adjustment. Providers might assume that other providers shed risk and the perception of added risk can influence practice. A poll was collected to examine such perceptions. METHODS: In 2019 a poll was sent to the 2800 surgeon members of the American Association of Hip and Knee Surgeons using Survey Monkey while protecting respondent anonymity/confidentiality. The questions asked whether the perception of poorly risk-adjusted medical comorbidities and socioeconomic risk factors influence surgeons to selectively offer surgery. RESULTS: There were 474 surgeon responses. Prior to elective total hip arthroplasty/total knee arthroplasty, 95% address modifiable risk factors; 52% require a body mass index <40, 64% smoking cessation, 96% an adequate hemoglobin A1C; 82% check nutrition; and 63% expect control of alcohol 2. Due to lack of socioeconomic risk adjustment, 83% reported feeling pressure to avoid/restrict access to patients with limited social support, specifically the following: Medicaid/underinsured, 81%; African Americans, 29%; Hispanics/ethnicities, 27%; and low socioeconomic status, 73%. Of the respondents, 93% predicted increased access to care with more appropriate risk adjustment. CONCLUSION: Competition-based quality/cost performance measures influence surgeons to focus on medical risk factors in offering lower extremity arthroplasty. The lack of socioeconomic risk adjustment leads to perceptions of added risk from such factors as well. This leads to marginal loss of access for patients within certain medical and socioeconomic classes, contributing to existing healthcare disparities. This represents an unintended consequence of competition-based performance measures.

Where Do We Stand Today on Racial and Ethnic Health Disparities? An Analysis of Primary Total Hip Arthroplasty From a 2011-2017 National Database.

BACKGROUND: Little is known about the persistence of health disparities in joint arthroplasty. The objective of this study was to update our knowledge on the state of racial and ethnic disparities in total hip arthroplasty (THA). METHODS: Patients undergoing primary, elective THA using the 2011-2017 American College of Surgeons National Surgical Quality Improvement Program were retrospectively reviewed. Five minority groups (non-Hispanic black or African American, Hispanic or Latino, Asian, American Indian or Alaska Native, and Native Hawaiian or Pacific Islander) were compared with non-Hispanic whites. The primary outcomes were in the differences in demographic characteristics, comorbidities, perioperative characteristics, THA utilization, length of stay (LOS), and 30-day adverse events (mortality, readmission, reoperation, and complications). RESULTS: A total of 155,870 patients were identified with racial and ethnic data available on 134,961 (86.6%) of them. Non-Hispanic white patients comprised 74.5% of all THA procedures. Except for Asians, all minority groups were more likely to be younger, have a higher body mass index, and smoke tobacco (P < .001). There were higher rates of nonprimary osteoarthritis, procedure length exceeding 100 minutes, and comorbidities among all minority groups. All minority groups, except Asian and Hawaiians or Pacific Islanders, were more likely to require an LOS >2 days. Blacks were more likely to develop surgical or medical complications (odds ratio [OR]: 1.21 and 1.2, respectively), whereas Hispanics or Latinos were more likely to develop surgical complications (OR: 1.28). American Indians or Alaska Natives were more likely to undergo reoperations (OR: 1.91). CONCLUSIONS: Health disparities persist among minority groups with respect to comorbidities, THA utilization, LOS, and complications. Blacks and Hispanics or Latinos appear to be the most impacted by these disparities.

Relation of Doximity ranking and matched applicant characteristics in orthopedic residency programs.

Orthopedic surgery residency applicants often turn to data from many online ranking platforms to select programs. The purpose of this study was to determine if programs belonging to different Doximity ranking groups and US geographical regions favor certain applicant characteristics in order to give prospective residents more data to make informed application decisions. 2019 Doximity rankings and matched applicant data from the 2019 Association of American Medical Colleges Residency Navigator were collected and used to determine differences among matched applicant characteristics in Doximity ranking groups and US regions. Matched applicants from the top Doximity ranking group had, on average, significantly more peer-reviewed publications than those of any other ranking group. Among US regions, matched applicants in South Atlantic programs had, on average, significantly fewer peer-reviewed publications than those in Mid Atlantic programs. Residents at South Atlantic programs spent a significantly higher percentage of their first-year training in ambulatory community settings than those in Mid Atlantic, Pacific, or East North Central programs. In conclusion, Doximity ranking is associated with certain applicant qualities more than others, and applicants can use the information in this study to strategically apply to institutions with similar training and educational goals.

Time Trends and Risk Factors for 30-Day Adverse Events in Black Patients Undergoing Primary Total Knee Arthroplasty.

BACKGROUND: Increased adverse events (AEs) have been reported among black patients undergoing joint arthroplasty, but little is known about their persistence and risk factors. The purpose of this study is (1) to examine recent annual trends in 30-day outcomes after total knee arthroplasty (TKA) and (2) to develop a preoperative risk stratification model in this racial minority. METHODS: The American College of Surgeons National Surgical Quality Improvement Program was queried for all black/African American patients who underwent primary TKA between 2011 and 2017. Time trends in demographic variables, comorbid conditions, perioperative characteristics, length of stay (LOS), and 30-day readmissions, reoperations, medical complications, surgical complications, and mortality were assessed. Multivariate logistic regression analyses were performed to identify independent risk factors for development of 30-day AEs. RESULTS: In total, 19,496 black patients were analyzed. Between 2011 and 2017, there have been improved comorbidity profiles (P < .02), decreased LOS (P < .001), and lower rates of AEs (P < .001). Significant risk factors for developing AEs were male gender, tobacco smoking, American Society of Anesthesiologists score >2, dependent functional status, congestive heart failure, chronic obstructive pulmonary disease, metastatic cancer, dyspnea, chronic kidney disease, bilateral TKA, and operative time >100 minutes. CONCLUSION: There have been significant improvements in the annual trends of LOS and 30-day outcomes among black patients undergoing primary TKA in recent years. A predictive model for 30-day AEs was developed to help guide risk stratification and optimization of modifiable factors, namely anemia, tobacco smoking, bilateral surgery, and operative time.

Analysis of Preoperative Screening Criteria for Total Joint Arthroplasty in a Veteran Population.

BACKGROUND: This study describes the experience of patients who initially failed total joint arthroplasty preoperative screening criteria but were subsequently optimized and underwent surgery. METHODS: Time to optimization from the patients' initial clinic visit was recorded. Following surgery, patients' body mass index and lab work were tracked to determine whether they "relapsed" to their preoptimized state. Descriptive statistics determined (1) the length of time to meet screening criteria and (2) which screening criteria took the longest to optimize. RESULTS: Only 11 of 84 patients (13%) required greater than 1 year to meet criteria. Most patients (76%) "relapsed" to their previous nonqualifying status after surgery; however, this reversion did not contribute significantly to an increased rate of complication in short-term follow-up (P = .4298). CONCLUSION: Patients in this study were able to achieve preoperative screening criteria for total joint arthroplasty in less than 1 year. Relapsing after surgery does not appear to adversely affect clinical outcomes.

The Distribution of Underrepresented Minorities in U.S. Orthopaedic Surgery Residency Programs.

BACKGROUND: Orthopaedic surgery has generally lagged behind other surgical subspecialties with respect to racial and ethnic diversity in its U.S. residency programs. Efforts have been made to increase the number of underrepresented minorities (URMs) applying to orthopaedic surgery residencies; however, the impact on diversity at the residency program level is unknown. The purpose of this study was to determine whether orthopaedic surgery residency programs have become more racially diverse over time. METHODS: The Graduate Medical Education Track database was queried for individual racial/ethnic identification of orthopaedic surgery residents in U.S. Accreditation Council for Graduate Medical Education (ACGME)-accredited programs for 15 consecutive years (2002-2003 through 2016-2017). The number of URMs in each residency program during each academic year was recorded. The number of programs per year with no URMs, 1 URM, 2 URMs, and >2 URMs was recorded, and the change over time was assessed. RESULTS: The number of programs per year with >1 URM resident decreased over time, from 61 programs in 2002 to 53 programs in 2016, with the trough being 31 programs in 2010 (p < 0.0001). The number of programs per year without any URM residents increased over the period of study, from 40 programs in 2002 to 60 programs in 2016, with the peak being 76 programs in 2011 (p < 0.0001). CONCLUSIONS: The number of residency programs with >1 URM resident has decreased significantly over time, suggesting that diversity at the program level is limited. Program-level diversity should be further examined as a potential barrier to the recruitment of URMs to orthopaedics. Difficulty attracting URM residents to certain programs may have the unintended consequence of effectively limiting potential positions for these candidates, which can decrease the odds of minority students matching into orthopaedics and, therefore, perpetuate the cycle of lack of diversity in our field.

The Orthopaedic Workforce Is Not as Diverse as the Population It Serves: Where Are the Minorities and the Women?: AOA Critical Issues Symposium.

The lack of sex and racial diversity of the physicians within the specialty of orthopaedic surgery was recognized decades ago, and formal steps to address these issues began in 1983 with the founding of the Ruth Jackson Orthopaedic Society and the J. Robert Gladden Orthopaedic Society. Despite the efforts of these organizations, the work of other interested groups, and the growing diversity in medical student demographics, physician diversity in orthopaedic surgery remains disproportionately poor relative to the populations that we serve as a specialty.

AML-induced osteogenic differentiation in mesenchymal stromal cells supports leukemia growth.

Genotypic and phenotypic alterations in the bone marrow (BM) microenvironment, in particular in osteoprogenitor cells, have been shown to support leukemogenesis. However, it is unclear how leukemia cells alter the BM microenvironment to create a hospitable niche. Here, we report that acute myeloid leukemia (AML) cells, but not normal CD34+ or CD33+ cells, induce osteogenic differentiation in mesenchymal stromal cells (MSCs). In addition, AML cells inhibited adipogenic differentiation of MSCs. Mechanistic studies identified that AML-derived BMPs activate Smad1/5 signaling to induce osteogenic differentiation in MSCs. Gene expression array analysis revealed that AML cells induce connective tissue growth factor (CTGF) expression in BM-MSCs irrespective of AML type. Overexpression of CTGF in a transgenic mouse model greatly enhanced leukemia engraftment in vivo. Together, our data suggest that AML cells induce a preosteoblast-rich niche in the BM that in turn enhances AML expansion.

Influence of gender on age of treatment with TKA and functional outcome.

BACKGROUND: Previous studies suggest differences may exist between men and women in terms of knee function before and after total knee replacement. This may be related to the efficacy of the procedure itself or to differences in the severity of disability of male and female patients at the time of surgery. QUESTIONS/PURPOSES: We evaluated differences in the age, preoperative deformity, range-of-motion, and Knee Society scores of men and women who underwent TKA. All parameters were measured at the time of the initial preoperative evaluation and at postoperative followup. METHODS: We studied 698 patients who underwent elective TKA between 1996 and 2007. This population consisted of 428 women (61%) and 270 men (39%), all of whom underwent rehabilitation utilizing a standardized hyperflexion protocol with immediate initiation of full weight-bearing postoperatively. RESULTS: The men were on average three years younger than the women (mean 63.5 versus 66.6 years, respectively). Preoperative ROM, postoperative ROM, and changes in ROM and body mass index were similar between groups. Knee Society Knee scores were similar preoperatively (47.4 [men] versus 46.7 [women]), but four points higher in men at followup (89.2 versus 85.2). Women had lower Knee Function scores than men preoperatively (45.2 versus 57.1), and postoperatively (65.3 versus 73.9). CONCLUSIONS: Women who undergo TKA seek treatment at a later stage than men and have greater functional disability at the time of surgery. Differences in functional scores persist after TKA. Earlier initiation of treatment may enhance postoperative outcome. LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Effects of femoral neck length, stem size, and body weight on strains in the proximal cement mantle.

BACKGROUND: Several studies have shown that certain cemented total hip replacement femoral stems have been associated with the complications of early debonding, loosening, and osteolysis. Some authors have suggested that these failures may be related to the surface finish of the stems. We developed an in vitro biomechanical experiment characterized by simulated stair-climbing to investigate the multiple factors involved in loosening of cemented femoral stems. In this study, we measured the effects of stem neck length, body weight, stem size, and calcar-collar contact on the torsional stability, as reflected by the strains in the proximal cement mantle, of one design of cemented femoral stem. METHODS: Eight Centralign femoral stems (Zimmer, Warsaw, Indiana) were cemented into eight cadaver femora with use of contemporary cementing techniques. Prior to insertion, fifteen strain-gauge rosettes were mounted around the proximal portion of the stem. The stems were loaded on a jig that simulated static peak loading during stair-climbing. Loading was repeated for each stem with three different joint reaction forces and for three different neck lengths. Calcar loading by the collar was then eliminated by removing a 0.5-mm slice of bone beneath the collar, and all loadings were then repeated. RESULTS: The peak principal tensile strains in the proximal cement increased linearly with both body weight (r (2) > 0.95) and neck length (r (2) > 0.75). Increasing body weight affected the peak cement strains far more than did increasing neck length. During simulated stair-climbing, calcar-collar contact reduced peak strains in the proximal cement by a factor of 1.5 to two. Peak principal tensile strains in the proximal cement often exceeded 1000 me when the smaller stems were used. CONCLUSIONS: In this stair-climbing test model, the peak proximal cement strains were increased more by changes in body weight than they were by changes in neck length. Even during stair-climbing, calcar-collar contact reduced peak cement strains.