Background Femoral periprosthetic fractures following total hip arthroplasty are a common cause for early revisions, especially in osteoporotic patients. Despite the protective nature of cemented stems, the widespread use of press-fit stems persists. The following biomechanical study quantifies resistance against subsidence and failure provided by a collar and triple taper stem design in a synthetic osteoporotic femur model. Methods Twenty-four synthetic osteoporotic femurs were instrumented with 4 uncemented stems (6 per group): single-wedge (blade) stems, triple-taper metaphyseal stems with and without a collar, and fit-and-fill stems. Each femur was subjected to 10,000 cycles of axial and torsional loading to simulate walking while the following outcomes measures were recorded: stem subsidence during axial loading, rotational stiffness, and torque to failure. Results The single-wedge stem experienced greater subsidence (1.4 ± 0.2 mm) compared to all other stem designs, while the triple-taper stem with a collar demonstrated the least amount of subsidence (0.53 ± 0.12 mm). The rotational stiffness of the collared triple-taper stem was significantly greater than the 3 other designs, and the maximum torque to failure for both triple-taper stem designs was significantly greater than the single-wedge stem and the fit-and-fill stem. Conclusions This study demonstrated superior biomechanical characteristics of collared triple-taper femoral stems compared to single-wedge, collarless triple-taper, and fit-and-fill stems. Clinically, this suggests collared stems should be considered when performing uncemented arthroplasty in patients with compromised bone.

Introduction:In 2021, the US Hispanic and Latino (H&L) population made up 19% of the national population, an increase from 14% in 2006. There is limited literature assessing the trends of H&L representation among residents, fellows, and attending physicians in orthopaedic surgery. We sought to analyze their current representation in light of recent changes in national demographics. Methods:Demographic data for the US population was obtained from the decennial Censuses. Race and ethnicity data for in-training residents from 2006 to 2021 were extracted from the Graduate Medical Education Census from the American Medical Association. Similar data were obtained from the 2008 and 2018 AAOS (American Academy of Orthopedic Surgeons) Censuses of fully trained orthopaedic surgeons. Representation was analyzed for the following groups: H&L, Black, Asian, Native American, Multiracial, and White. H&L fellows representation per subspecialty (adult reconstruction, foot and ankle, hand, oncology, sports medicine, spine, trauma, and pediatrics) was also analyzed. Results:A total of 57,187 orthopaedic surgery residents were in training over the 15-year study period (2006-2021), 2,812 (4.9%) identified as H&L. Total number of orthopaedic residents in-training grew by 36% from 2006 to 2021 (3,305 to 4,616). H&L residents doubled from 118 to 281 to comprise 6.1% of trainees. Representation for H&L trained orthopaedic surgeons grew from 484 (1.9%) in 2008 to 663 (2.2%) in 2018, a 37% increase in absolute number and 16% as percentage of the orthopaedic workforce. Conclusion:Across the 15-year study period, H&L representation in orthopaedic surgery moderately increased at all levels but remained low relative to the H&L population. H&L resident representation relative to H&L national demographic weight is significantly low (p < 0.001) compared with other ethnic/racial groups. H&L residents were represented at a rate 3 times lower than White residents and almost 7 times lower than Asian residents when compared with the H&L national population.

Arthrofibrosis is a complication after total knee arthroplasty (TKA) that can limit functionality and cause dissatisfaction. This study assesses the prevalence of preoperative depressive symptoms amongst patients who required manipulation under anesthesia (MUA) for arthrofibrosis after TKA. Patients who underwent primary TKA with need for subsequent MUA were age and sex matched to control patients who underwent primary TKA without requiring MUA. Preoperative and postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) scores for function, pain, and depression as well as range of motion in both groups were compared. There were 16 MUA patients and 48 non-MUA patients included in this study. There was a significantly higher percentage of patients with preoperative depression in the MUA group (62.5% vs. 10.4%, p < 0.001). (Journal of Surgical Orthopaedic Advances 34(2):078-081, 2025).

Background:In 2013, the Accreditation Council of Graduate Medical Education (ACGME) instituted a case minimum requirement for orthopaedic residents. It is unknown how pediatric orthopaedic case volume and variability have been affected by this change. Methods:The ACGME orthopaedic surgery case log data from 2007 to 2020 were used to evaluate the number and type of pediatric orthopaedic procedures logged by graduating residents. The mean and median number of cases logged were compared for the years before (2007-2013) and after (2014-2020) the case minimum implementation using a Student t-test. Results:In the period after case minimum implementation, there were significant decreases in both overall cases (2080.6-1639.2; P < .001) and pediatric cases (328.7-264.7; P < .001) logged by residents. However, pediatric case volumes in certain areas significantly increased. Pediatric humerus/elbow procedures went up by 19.7% (29.4-35.2; P < .001), driven by an increase in fracture and dislocation treatments (21.5-28.17, 31.0%; P < .001). Similarly, pediatric forearm/wrist procedures went up by 31.7% (33.7-44.5; P < .001), driven by an increase in manipulation (19.0-31.9, 67.8%; P < .001). All other anatomic areas besides the shoulder experienced significant decreases in case volume, including spine procedures, which experienced the greatest decrease: 52.1% (28.4-13.5; P < .001). Conclusions:Paradoxically, since the implementation of case minimums in 2013, residents have logged fewer overall cases and pediatric orthopaedic cases. One may hypothesize that, when residents are required to submit a certain minimum number of cases, there is little incentive to submit additional cases. Key Concepts:1)The ACGME instituted a case minimum requirement for Orthopaedic surgery residents starting in 2013.2)Since 2013, residents have logged fewer pediatric orthopaedic cases.3)Since 2013, residents have logged fewer overall orthopaedic cases. Level of Evidence:III, Cross-Sectional Study.

Arthrofibrosis after primary total knee arthroplasty (TKA) is a significant contributor to patient dissatisfaction. While treatment algorithms involve early physical therapy and manipulation under anaesthesia (MUA), some patients ultimately require revision TKA. It is unclear whether revision TKA can consistently improve these patient's range of motion (ROM). The purpose of this study was to evaluate ROM when revision TKA was performed for arthrofibrosis. A retrospective study of 42 TKA’s diagnosed with arthrofibrosis from 2013 to 2019 at a single institution with a minimum 2-year follow-up was performed. The primary outcome was ROM (flexion, extension, and total arc of motion) before and after revision TKA, and secondary outcomes included patient reported outcomes information system (PROMIS) scores. Categorical data were compared using chi-squared analysis, and paired samples t tests were performed to compare ROM at three different times: pre-primary TKA, pre-revision TKA, and post-revision TKA. A multivariable linear regression analysis was performed to assess for effect modification on total ROM. The patient's pre-revision mean flexion was 85.6 degrees, and mean extension was 10.1 degrees. At the time of the revision, the mean age of the cohort was 64.7 years, the average body mass index (BMI) was 29.8, and 62

» Metallosis is a rare but significant complication that can occur after total hip arthroplasty (THA) for a variety of reasons but most commonly in patients with metal-on-metal implants.» It is characterized by the visible staining, necrosis, and fibrosis of the periprosthetic soft tissues, along with the variable presence of aseptic cysts and solid soft tissue masses called pseudotumors secondary to the corrosion and deposition of metal debris.» Metallosis can present with a spectrum of complications ranging from pain and inflammation to more severe symptoms such as osteolysis, soft tissue damage, and pseudotumor formation.» Workup of metallosis includes a clinical evaluation of the patient's symptoms, imaging studies, serum metal-ion levels, and intraoperative visualization of the staining of tissues. Inflammatory markers such as erythrocyte sedimentation rate and C-reactive protein along with intraoperative frozen slice analysis may be useful in certain cases to rule out concurrent periprosthetic joint infection.» Management depends on the severity and extent of the condition; however, revision THA is often required to prevent rapid progression of bone loss and tissue necrosis.

Background: Serum cluster of differentiation 64 (CD64) has emerged as a diagnostic test for musculoskeletal infections. The purpose of this study was to evaluate the utility of serum CD64 in diagnosing periprosthetic joint infections (PJIs) compared to conventional markers like white blood count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and interleukin-6 (IL-6).Methods: A prospective case-control study on patients undergoing revision hip or knee arthroplasty surgery >6 weeks after their index surgery was performed at a single institution. Whole blood samples were drawn within 24 hours prior to revision surgery for white blood count, ESR, CRP, IL-6, and CD64. Intraoperative cultures were obtained during the revision, and PJI was defined using the major criteria from the 2018 Musculoskeletal Infection Society criteria. Two-sample Wilcoxon rank-sum test and Fisher's exact test were used to determine if there were significant differences in serum laboratory values between patients with and without infection. The sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy of each test were calculated.Results: With an average age of 67 years, 39 patients with 15 revision THAs and 24 TKAs, were included. 19 patients (48.7%) were determined to have PJI. Patients with PJI had significantly higher CD64 (P = .036), CRP (P = .016), and ESR (P = .045). CD64 had the highest specificity (100%) and PPV (100%), moderate accuracy (69.2%), but low sensitivity (37.0%) and negative predictive value (62.5%).Conclusions: Given the high specificity, PPV, and accuracy, CD64 may be an excellent confirmatory test to help diagnose PJI.(c) 2023 The Authors. Published by Elsevier Inc. on behalf of The American Association of Hip and Knee Surgeons. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Background: Although 2-stage exchange arthroplasty, consisting of temporary insertion of an antibiotic impregnated cement spacer (AICS), is considered the standard of care for chronic periprosthetic joint infection (PJI) in total hip arthroplasty (THA), a consensus on the AICS design has not yet been established. Ceramic-on-polyethylene AICSs (Poly-AICS) are theorized to cause less pain and better function than cement-on-bone AICS (CemB-AICS) but use non-antibiotic-impregnated components that may harbor bacteria. This study evaluates the impact of spacer design on infection-free survivorship following THA reimplantation as well as pain and function during the interim AICS stage.Methods: A retrospective review was performed of all cases of THA PJI treated with either Poly-AICS or CemB-AICS at a single high-volume academic center. Data were collected until the final follow-up after THA reimplantation with an average follow-up duration of 2.6 years. The primary outcome was infection free survivorship after the final reimplantation. Secondary outcomes included postoperative pain scores, opioid use, time to ambulation, length of stay, complications, and discharge disposition.Results: A total of 99 cases (67 CemB-AICS; 32 Poly-AICS) were included. There were no baseline differences between the 2 groups. There were no differences in infection-free survivorship after reimplantation in survivorship curve comparisons (P 1/4 .122) and no differences in postoperative inpatient pain scores, opioid use, length of stay, time to ambulation, complications, or discharge disposition during the AICS stage.Conclusions: Patients with THA PJI treated with Poly-AICS did not have worse infection-related outcomes despite the use of non-antibiotic-impregnated components but also did not appear to have less pain or improved function during the early AICS stage.(c) 2022 The Authors. Published by Elsevier Inc. on behalf of The American Association of Hip and Knee Surgeons. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

BACKGROUNDIn response to COVID-19, American medical centers have enacted elective case restrictions, markedly affecting the training of orthopaedic residents. Residencies must develop new strategies to provide patient care while ensuring the health and continued education of trainees. We aimed to describe the evolving impact of COVID-19 on orthopaedic surgery residents.METHODSWe surveyed five Accreditation Council for Graduate Medical Education-accredited orthopaedic residency programs within cities highly affected by the COVID-19 pandemic about clinical and curricular changes. An online questionnaire surveyed individual resident experiences related to COVID-19.RESULTSOne hundred twenty-one resident survey responses were collected. Sixty-five percent of the respondents have cared for a COVID-19-positive patient. One in three reported being unable to obtain institutionally recommended personal protective equipment during routine clinical work. All programs have discontinued elective orthopaedic cases and restructured resident rotations. Most have shifted schedules to periods of active clinical duty followed by periods of remote work and self-isolation. Didactic education has continued via videoconferencing.DISCUSSIONCOVID-19 has caused unprecedented changes to orthopaedic training; however, residents remain on the front lines of inpatient care. Exposures to COVID-19 are prevalent and residents have fallen ill. Programs currently use a variety of strategies to provide essential orthopaedic care. We recommend continued prioritization of resident safety and necessary training accommodations.

Given a national push toward bundled payment models, the purpose of this study was to examine the prevalence as well as the effect of smoking on early inpatient complications and cost following elective total knee arthroplasty (TKA) in the United States across multiple years. Using the nationwide inpatient sample, all primary elective TKA admissions were identified from 2012 to 2014. Patients were stratified by smoking status through a secondary diagnosis of "tobacco use disorder." Patient characteristics as well as prevalence, costs, and incidence of complications were compared. There was a significant increase in the rate of smoking in TKA from 17.9% in 2012 to 19.2% in 2014 ( p < 0.0001). The highest rate was seen in patients < 45 years of age (27.3%). Hospital resource usage was significantly higher for smokers, with a length of stay of 3.3 versus 2.9 days ( p < 0.0001), and hospital costs of $16,752 versus $15,653 ( p < 0.0001). A multivariable logistic model adjusting for age, gender, and comorbidities showed that smokers had an increased odds ratio for myocardial infarction (5.72), cardiac arrest (4.59), stroke (4.42), inpatient mortality (4.21), pneumonia (4.01), acute renal failure (2.95), deep vein thrombosis (2.74), urinary tract infection (2.43), transfusion (1.38) and sepsis (0.65) (all p < 0.0001). Smoking is common among patients undergoing elective TKA, and its prevalence continues to rise. Smoking is associated with higher hospital costs as well as higher rates of immediate inpatient complications. These findings are critical for risk stratification, improving of bundled payment models as well as patient education, and optimization prior to surgery to reduce costs and complications.

Background: Smoking is a potentially modifiable risk factor that may impact the overall outcomes of total hip arthroplasty (THA). In an era of bundled payments for THA, the purpose of this study was to evaluate, on a national level, the inpatient complications and additional costs of smokers undergoing THA. Methods: The Nationwide Inpatient Sample was used to identify all primary elective THAs performed in the United States in 2014. This cohort was further stratified by smoking status. Inpatient hospital characteristics, costs, and complications rates were assessed. Results: The Nationwide Inpatient Sample had 63,446 admissions recorded for primary THAs in 2014, corresponding to an estimated 317,230 cases nationwide. The smoking rate was 20.7%. Smokers were slightly yet significantly younger than nonsmokers (63.5 years vs 64.8 years; P <. 0001). The smoking group had a significantly longer hospital stay and higher total hospital costs (both P <. 0001). After using a multivariable logistic model adjusting for age, gender, and comorbidities, smokers were found to have a significantly higher odds ratio (OR [95% confidence interval {CI}]) for myocardial infarction (15.5 [5.0-47.5]), cardiac arrest (10.1 [2.2-47.6]), pneumonia (4.7 [2.4-9.1]), urinary tract infection (1.9 [1.4-2.7]), sepsis (13.1 [3.5-49.0]), acute renal failure (2.9 [2.2-3.7]), discharge to a skilled nursing facility (1.3 [1.2-1.4]), and mortality (11.7 [2.0-70.5]). Conclusions: Smoking remains a highly prevalent and important risk factor for complications in elective primary THA in the United States. Patients who smoke have a significantly higher rate of complications and generate significantly higher postoperative inpatient costs. These findings are important for risk stratification, bundled payment considerations, as well as perioperative patient education and intervention. (c) 2019 Elsevier Inc. All rights reserved.

BACKGROUND:This study provides a comprehensive analysis of total hip arthroplasty (THA) revisions in the U.S. from 2007 to 2013. METHODS:International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to identify all THA revisions in the Nationwide Inpatient Sample (NIS) from 2007 to 2013. The diagnoses leading to the revisions, types of revisions, major inpatient complications, and hospital and patient characteristics were compared between 2007 and 2013. Multivariable logistic regression models were used to calculate adjusted odds ratios (ORs) for complications in 2013 versus 2007. RESULTS:This study identified 320,496 THA revisions performed between 2007 and 2013. From 2007 to 2013, the THA revision rate adjusted for U.S. population growth increased by 30.4% in patients between 45 and 64 years of age and decreased in all other age groups. The rate of surgically treated THA dislocations decreased by 14.3% from 2007 to 2013 (p < 0.0001). The mean length of the hospital stay and hospital costs for THA revision were significantly lower in 2013 than in 2007 (4.6 versus 5.8 days and $20,463 versus $25,401 both p < 0.0001). A multivariable model showed that the odds of a patient undergoing THA revision having the following inpatient complications were significantly lower in 2013 than in 2007: deep vein thrombosis (OR = 0.57, p = 0.004), pulmonary embolism (OR = 0.45, p = 0.047), myocardial infarction (OR = 0.52, p = 0.003), transfusion (OR = 0.64, p < 0.0001), pneumonia (OR = 0.56, p < 0.0001), urinary tract infection (OR = 0.66, p < 0.0001), and mortality (OR = 0.50, p = 0.0009). Notably, the odds of being discharged to a skilled nursing facility were also lower in 2013 than in 2007 (OR = 0.71, p < 0.0001). CONCLUSIONS:The THA revision rate has significantly increased in patients between 45 and 64 years of age. However, the rate of surgically treated THA dislocations has decreased significantly. This may indicate that evolving techniques and implants are improving stability. The rate of inpatient complications following THA revision also decreased significantly from 2007 to 2013. LEVEL OF EVIDENCE:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

We present a unique case of a symptomatic adverse local tissue reaction in a patient with a ceramic-on-ceramic total hip bearing surface. To our knowledge, this pathological finding has not yet been described in a ceramic-on-ceramic articulation without a cobalt-chromium alloy trunnion or modular neck component as a source of metal wear. We conclude that despite its mechanical mostly benign wear characteristics, ceramic wear debris is not entirely inert and may lead to the development of adverse local tissue reaction.

1South Bay Orthopaedic Specialists, 23560 Crenshaw Boulevard, Suite 120, Torrance, CA 90505. E-mail address: [email protected] 2Department of Orthopaedic Surgery, Cedars-Sinai Medical Center, 444 South San Vicente Blvd., OC – 603, Los Angeles, CA 90048

OBJECTIVES:The use of locked plates in repairing osteopenic 3- and 4-part proximal humerus fractures remains controversial. The purpose of this article was to report the outcomes of open reduction and internal fixation in low-energy proximal humerus fractures treated with locked plating in patients older than 55 years and stratify risk of failure or complication based on initial radiographic features. DESIGN:Retrospective. SETTING:Level I Trauma Center. METHODS:Seventy patients older than 55 years undergoing locked plate fixation for Neer 3- or 4-part proximal humerus fractures were studied retrospectively. All patients had standardized, true size digital radiographs of the injured and normal shoulder in the axillary, scapular Y, and 20-degree external rotation views with a minimum of 18 months' clinical follow-up. Two groups were identified based on the initial direction of the humeral head deformity: varus or valgus impaction. There were no statistical differences between treatment groups with regard to age, sex, Neer classification, follow-up, or dislocation. Radiographic measurements included humeral head angulation, tuberosity displacement, and length of the intact metaphyseal segment. Clinical outcomes measured Constant scores (CS) using active range of motion at latest follow-up. RESULTS:Twenty-four patients with initial varus fracture patterns healed with an average of 16-degree varus head angulation and an overall CS of 63 at an average of 34 months' follow-up. Forty-six patients with initial valgus fracture patterns healed with an average of 6 degrees of varus angulation and an overall CS of 71 at an average of 37 months' follow-up (P < 0.01). Complications of avascular necrosis, humeral head perforation, loss of fixation, tuberosity displacement >5 mm, and varus subsidence >5 degrees were encountered in 19 of 24 (79%) in the varus group compared with 9 of 46 (19%) in the valgus group (P < 0.01). Final CSs for 3-part fractures were 65 versus 72 (P < 0.01) for varus and valgus groups, respectively, and 61 versus 69 (P = 0.19) for 4-part fractures. CONCLUSIONS:Neer 3- and 4-part proximal humeral fractures in older patients with initial varus angulation of the humeral head had a significantly worse clinical outcome and higher complication rate than similar fracture patterns with initial valgus angulation. Two factors had significant influence on final outcome in these fracture patterns: initial direction of the humeral head angulation and length of the intact metaphyseal segment attached to the articular fragment. The best clinical outcomes were obtained in valgus impacted fractures with a metaphyseal segment length of greater than 2 mm, and this was independent of Neer fracture type. Humeral head angulation had the greatest effect on final outcomes (P < 0.001), whereas metaphyseal segment length of less than 2 mm was predictive of developing avascular necrosis (P < 0.001).

BACKGROUND Optimal surgical management of three and four-part proximal humeral fractures in osteoporotic patients is controversial, with many advocating prosthetic replacement of the humeral head. Fixed-angle locked plates that maintain angular stability under load have been proposed as an alternative to hemiarthroplasty for the treatment of some osteoporotic fracture types. METHODS The records of 122 consecutive patients who were fifty-five years of age or older and in whom a Neer three or four-part proximal humeral fracture had been treated surgically between January 2002 and November 2005 were studied retrospectively. After exclusions, thirty-eight patients treated with a locked-plate construct were compared with forty-eight patients who had undergone hemiarthroplasty. All patients had radiographic and clinical follow-up at a minimum of twenty-four months and an average of thirty-six months. Reduction and implant placement were evaluated radiographically. Clinical outcomes were measured with use of the Constant-Murley system. RESULTS The mean Constant score (and standard deviation) at the time of final follow-up was significantly better in the locked-plate group (68.6 +/- 9.5 points) than in the hemiarthroplasty group (60.6 +/- 5.9 points) (p < 0.001). The Constant scores for the three-part fractures in the locked-plate and hemiarthroplasty groups were 71.6 and 60.4 points (p < 0.001), respectively, and the scores for the four-part fractures in those groups were 64.7 and 60.1 points (p = 0.19), respectively. Patients with an initial varus extension deformity in the locked-plate group had significantly worse outcomes than those with a valgus impacted pattern (Constant score, 63.8 compared with 74.6 points, respectively; p < 0.001). Complications in the group treated with locked-plate fixation included osteonecrosis in six patients, screw perforation of the humeral head in six patients, loss of fixation in four patients, and wound infection in three patients. Loss of fixation was seen only in patients with >20 degrees of initial varus angulation of the humeral head. Complications in the hemiarthroplasty group included nonunion of the tuberosity in seven patients and wound infection in three patients. CONCLUSIONS In this series, open repair with use of a locked plate resulted in better outcome scores than did hemiarthroplasty in similar patients, especially in those with a three-part fracture, despite a higher overall complication rate. Open reduction and internal fixation of fractures with an initial varus extension pattern should be approached with caution.

Musculoskeletal manifestations of the human immunodeficiency virus (HIV) are common and are sometimes the initial presentation of the disease. Knowledge of the conditions affecting muscle, bone, and joints in HIV-infected patients is essential for successful management. Myopathies may be caused by pyogenic infection (eg, pyomyositis), idiopathic inflammation (eg, polymyositis), or drug effect (eg, AZT myopathy). Characteristic skeletal infections, such as tuberculosis and bacillary angiomatosis, require a high index of suspicion for accurate diagnosis. Neoplastic processes, such as non-Hodgkin's lymphoma and Kaposi's sarcoma, occur more frequently as the immune system deteriorates. Inflammatory and reactive arthropathies are more prevalent in HIV-positive than HIV-negative individuals and include Reiter's syndrome, psoriatic arthritis, HIV-associated arthritis, painful articular syndrome, acute symmetric polyarthritis, and hypertrophic osteoarthropathy. Patients with atypical musculoskeletal complaints and a suspected history of exposure should be tested for HIV.

Deep vein thrombosis (DVT) is the most frequent complication after total hip arthroplasty, and proximal DVT is more likely to produce clinical pulmonary emboli than distal DVT. The authors have assessed the incidence and anatomic location of phlebographically proven fresh DVT following total hip arthroplasty in 855 patients over 39 years of age. Eight different regimens (2 warfarin, 3 aspirin, 1 dextran, 1 external pneumatic compression, and 1 dextran combined with external pneumatic compression) were evaluated and compared with an historical placebo control group from the same institution. No significant difference (P < .05) existed in proximal DVT incidence between the placebo group and any of the three aspirin groups, the dextran group, the external pneumatic compression group, or the dextran combined with external pneumatic compression group. In contrast, warfarin, given both in traditional and low-dose regimens, provided a significant reduction in proximal DVT compared with the placebo group (P < .001; statistical power, 0.84 and 0.99, respectively). The low-dose regimen had 10 times fewer bleeding complications than the traditional regimen. All prophylaxis regimens should be evaluated for both proximal and distal DVT formation, as well as for overall incidence. Low-dose warfarin offers the best protection against proximal thrombi of the agents studied, and it is also safer than traditional dosages of warfarin.