Late deep venous thrombosis and delayed weightbearing after total hip arthroplasty

An analysis of risk factors for venous thromboembolism in primary versus revision total joint arthroplasty

Background

One of the most serious complications after primary or revision lower extremity total joint arthroplasty (TJA) is venous thromboembolism disease (VTE). Identifying patients at high risk for VTE allows tailoring of prophylactic anticoagulation regimens to those most vulnerable. This study aimed to identify risk factors for VTE in primary and revision lower extremity TJA.

Methods

The Electronic Medical Record was queried from a single academic institution for all patients who underwent a lower extremity TJA between 2007 and 2020. Demographics, comorbid conditions, perioperative characteristics, and postoperative complications were identified. An Elastic Net Multiple Logistic Regression Model was used to assess 49 covariates and predict those associated with a significant risk of VTE.

Results

We identified 4900 primary and revision total knee arthroplasty (TKA) and total hip arthroplasty (THA) patients. There was no significant difference between primary and revision THA. Primary TKA had a higher rate of VTE than revision TKA. Significant risk factors identified for VTE in THA patients include histories of deep vein thrombosis (DVT), pulmonary embolism (PE), metastatic tumors, hemiplegia, and Hispanic ethnicity. Risk factors for VTE in TKA patients include histories of DVT, PE, metastatic tumors, and postoperative warfarin and heparin use. In all patients, age was a significant predictor of VTE risk.

Conclusion

Our work identifies many risk factors for VTE following TJA. While the increased rate of VTE in some populations may represent selection bias, it also highlights the incomplete understanding of the etiology and prevention of this complication in the joint arthroplasty population and requires further study.

Benefits of early ambulation within 24 h after total knee arthroplasty: a multicenter retrospective cohort study in China

BACKGROUND

Postoperative care has been evolving since the concept of enhanced recovery after surgery (ERAS) was introduced in China. This study aimed to evaluate the effects of early ambulation within 24 h after unilateral total knee arthroplasty (TKA) on postoperative rehabilitation and costs in a Chinese population.

METHODS

This cohort study of patients with knee osteoarthritis who had undergone TKA at 24 large teaching hospitals between January 2014 and November 2016 involved 2687 patients who began ambulating within 24 h (Group A) and 3761 who began ambulating later than 24 h (Group B). The outcome measurements, such as length of stay (LOS), total hospitalization costs, dynamic pain level, knee flexion range of motion (ROM), results of the 12-Item Short Form Survey (SF-12), incidence of thromboembolic events and other complications, were recorded and compared.

RESULTS

The early ambulation group (Group A) had a shorter LOS and lower hospitalization costs and pain levels than the late ambulation group (Group B). There was a favorable effect in enhancing ROM for patients in Group A compared with patients in Group B. In Group A, patients had significantly higher postoperative SF-12 scores than those in Group B. The incidence of deep venous thrombosis (DVT) and pulmonary infection was significantly lower in Group A than in Group B. The incidence of pulmonary embolism (PE) and other complications did not differ between the two groups.

CONCLUSION

Early ambulation within 24 h after TKA was associated with reduced LOS, improved knee function, lower hospitalization costs and lower incidence of DVT and pulmonary infection in the Chinese population.

Manual calf massage and passive ankle motion reduce the incidence of deep vein thromboembolism after total hip arthroplasty

BACKGROUND

Venous thromboembolism is one of the general complications following total hip arthroplasty, wherein various preventive treatments have been recommended. Several studies reported that venous thromboembolism incidence after total hip arthroplasty was similar in patients who were administered prophylaxis with a conventional mechanical procedure alone, and those who were administered pharmacological anticoagulation therapy. Therefore, the optimum methods of prophylaxis are still controversial. The purpose of this study was to investigate whether manual calf massage and passive ankle motion could lower the risk for venous thromboembolism after total hip arthroplasty.

METHODS

We retrospectively reviewed the data of 126 consecutive patients undergoing elective primary unilateral total hip arthroplasty wherein manual calf massage and passive ankle motion were performed after the surgery at our hospitals between January and October 2014. The 138 patients of the control group underwent total hip arthroplasty using the same surgical approach and pre- and postoperative protocols without this mechanical prophylaxis between January and December 2013. This mechanical prophylaxis was performed simultaneously 30 times during approximately 10 s; these procedures were repeated thrice immediately after total hip arthroplasty. Duplex ultrasonography was performed to observe the veins of both legs in all the patients on postoperative day 7.

RESULTS

The incidence of deep vein thrombosis was 6.52% and 0.79% in the control and manual calf massage and passive ankle motion groups, respectively. The odds ratio for the manual calf massage and passive ankle motion groups was 8.72. Performing this mechanical prophylaxis reduced the incidence of venous thromboembolism after total hip arthroplasty. This mechanical prophylaxis is not only simple and easy, but is also safe and inexpensive.

CONCLUSIONS

We therefore recommend that manual calf massage and passive ankle motion be performed in patients who will undergo total hip arthroplasty, if deep vein thrombosis does not exist before the surgery.

Patient-Controlled Fentanyl Iontophoretic Transdermal System Improved Postoperative Mobility Compared to Intravenous Patient-Controlled Analgesia Morphine: A Pooled Analysis of Randomized, Controlled Trials

BACKGROUND

Postoperative pain management protocols that use patient-controlled analgesia (PCA) can hinder mobility due to attached machinery and tubing. Immobility in the postoperative setting can increase complications, length of stay (LOS), and costs. Early and enhanced mobilization can reduce the cost of care while improving patient outcomes. A needle-free, compact, patient-activated, and portable fentanyl iontophoretic transdermal system (fentanyl ITS, IONSYS; The Medicines Company, Parsippany NJ) has been shown to provide comparable efficacy and tolerability to intravenous (IV) PCA morphine that promotes improved mobility.

METHODS

This pooled analysis of 1,882 patients across three randomized, controlled trials compared fentanyl ITS to IV PCA morphine for postoperative pain management. Outcomes of patient mobility were assessed by a validated Patient Ease of Care Questionnaire that was given to patients, patients' nurses, and physical therapists involved in patient care. Safety was assessed via spontaneously reported treatment-emergent adverse events (TEAE).

RESULTS

Fentanyl ITS significantly improved overall patient mobility, each mobility subscore (P < 0.0001) across all demographics (male/female; elderly/non-elderly; normal BMI/overweight/obese/morbidly obese) and surgery types, and was consistent across nurses and physical therapists mobility assessments. TEAEs were generally similar between the two groups. However, more patients reported an opioid-related TEAE with morphine IV PCA than with fentanyl IV PCA (P = 0.003).

CONCLUSION

Due to improved mobility with fentanyl ITS, complications are expected to be less frequent than with IV PCA and epidural PCA. Incorporation of this strategy into postoperative pain management protocols may reduce LOS and total hospital costs.

Agreements and disagreements in exercise therapy prescriptions after hip replacement among rehabilitation professionals: a multicenter survey

Background

Exercise therapy following total hip replacement (THR) is considered to be important during the initial postoperative care, but till date only a few evidence-based recommendations exist. The aim of this survey was to identify prescription standards among different rehabilitation professionals, for the exercise therapy management after THR in Germany.

Methods

The study was a cross-sectional survey. Standardized questionnaires were sent to 38 eligible rehabilitation facilities in Germany. Participating surgeons, orthopaedic physicians, physiotherapists and exercise therapists rated the optimal early weight-bearing, resistance training, key components and dose of exercise therapy, and the hip loading during exercising. The returned questionnaires were then analyzed for level of agreement (≥80 %) among respondents.

Results

313 rehabilitation professionals from 28 clinics returned completed questionnaires and were considered eligible for analysis. Out of total respondents, 53.9 % (cemented THR) and 18.2 % (uncemented THR) recommended full weight-bearing within five days after surgery. Commencement of resistance training later than three weeks after surgery is recommended by 20.6 % (36 %) for cemented (uncemented) prosthesis. Feedback varied significantly amongst the professions. Regarding the overall objectives of rehabilitation after hip replacement, respondents agree in six out of eight requested items. Agreement concerning priorities of specific exercises was achieved in three out of twelve items. The recommended exercise therapy dose varied significantly with working experience (p = 0.02).

Conclusion

Rehabilitation professionals mainly disagreed with the exercise therapy prescriptions following the total hip replacement during the initial postoperative care in Germany.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0646-7) contains supplementary material, which is available to authorized users.

Extended therapy for primary and secondary prevention of venous thromboembolism

Clinical practice guidelines currently suggest extended anticoagulation therapy for primary and secondary prevention of venous thromboembolism (VTE). The optimal duration of anticoagulation has been an active area of clinical investigation for patients undergoing orthopedic surgeries and those diagnosed with a first episode of unprovoked VTE. Practice guidelines, VTE incidence, clinical predictors/mediators, and clinical trial evidence is reviewed to help pharmacists and other health care providers make an informed, patient-specific decision on the optimal duration of anticoagulation therapy. Extended anticoagulation up to 5 weeks following orthopedic surgery for primary VTE prevention and indefinitely following a first episode of unprovoked VTE for secondary VTE prevention should be considered only if the risk of bleeding is not high and the cost and burden of anticoagulation is acceptable to the patient. The optimal duration of anticoagulation therapy for primary or secondary prevention of VTE should include the health care provider and patient making a decision based on evaluation of individual benefits, risks, and preferences.

Is routine chemical thromboprophylaxis after total hip replacement really necessary in a Japanese population?

Prophylaxis against venous thromboembolism after elective total hip replacement is routinely recommended. Our preference has been to use mechanical prophylaxis without anticoagulant drugs. A randomised controlled trial was performed to evaluate whether the incidence of post-operative venous thromboembolism was reduced by using pharmacological anticoagulation with either fondaparinux or enoxaparin in addition to our prophylactic mechanical regimen. A total of 255 Japanese patients who underwent primary unilateral cementless total hip replacement were randomly assigned to one of three postoperative regimens, namely injection of placebo (saline), fondaparinux or enoxaparin. There were 85 patients in each group. All also received the same mechanical prophylaxis during and after the operation, regardless of their assigned group. The primary measurement of efficacy was the presence of a venous thromboembolic event by day 11, defined as deep-vein thrombosis detected by ultrasonography, documented symptomatic deep-vein thrombosis or documented symptomatic pulmonary embolism. The duration of follow-up was 12 weeks.

The rate of venous thromboembolism was 7.2% with the placebo, 7.1% with fondaparinux and 6.0% with enoxaparin (p = 0.95 for the comparison of all three groups). Our study confirmed the effectiveness and safety of mechanical thromboprophylaxis without the use of anticoagulant drugs after total hip replacement in Japanese patients.

Partial weightbearing is not necessary after cementless total hip arthroplasty: a two-year prospective randomized study on 100 patients

The purpose of this study was to evaluate the effects of partial and full weightbearing after cementless total hip arthroplasty over a two year follow-up period. Fifty-nine women and 41 men (average age 61 years) received an uncemented Spotorno stem and were randomised into a full and a partial weightbearing group. No significant difference was found between the groups with regard to the Merle d' Aubigne hip score, VAS pain level, shaft migration or radiographic signs of bony ingrowth. All femoral components seemed radiologically well-fixed and showed bone ingrowth at 24 months. Provided that solid initial fixation is obtained full weightbearing immediately after cementless total hip arthroplasty using a hydroxyapatite-coated Spotorno-type femoral shaft component can be recommended.

[Thromboembolic disease in orthopedic surgery]

Thromboembolic complications are frequent after orthopaedic surgery of the limbs. Strategies to minimize these complications go from recognize the risk factors of the patient to introduce new antithrombotic drugs, and including general medical care, regional anaesthesia and early mobilization. Based in epidemiological studies, prophylaxis must be extended 4-6 weeks in total hip and knee arthroplasty and in surgery of the hip fracture.

Thromboembolic Therapies in Dogs and Cats: An Evidence-Based Approach

In veterinary medicine, we are forced to make use of less than ideal "evidence," such as extrapolation from experimental studies in dogs and cats without naturally occurring diseases and from clinical trials in other species (particularly human clinical trials), as well as limited information gained from veterinary clinical experience, small clinical trials, case studies, and anecdotal reports. In this article, specific treatment recommendations are made for each of the common thromboembolic conditions seen in dogs and cats. These recommendations are made with the important caveat that, to date, such suggested therapeutic approaches are based on limited evidence.

Thromboembolic disease after total hip arthroplasty: who is at risk?

The strong activation of the clotting cascade that occurs during total hip arthroplasty places patients at increased risk for venous thromboembolism. The risk is higher in those patients with the following predisposing factors, listed in approximate order of importance: hip fracture; malignancy, particularly if associated with chemotherapy; antiphospholipid syndrome; immobility; history of venous thromboemholism; administration of tamoxifen; raloxifene; oral contraceptives or estrogen; morbid obesity; stroke; atherosclerosis; and an American Society of Anesthesiologists physical status classification of 3 or greater. The following risk factors are weak or controversial: advanced age; diabetes mellitus; congestive heart disease; atrial fibrillation; varicose veins; and smoking. However, 50% of patients who develop thromboembolism after total hip arthroplasty have no clinical predisposing factors. In a matched, controlled study, we defined the major genetic predispositions that increase the risk of venous thromboembolism after total hip arthroplasty: deficiency of antithrombin III (< 75%) and protein C (< 70%), and prothrombin gene mutation. Preoperative genetic screening in conjunction with the recognized clinical risk factors can help categorize postoperative venous thromboembolism risk and differentiate patients who can be protected with milder and safer prophylaxis (eg, aspirin, intermittent pneumatic compression) compared with those at higher risk who need to be anticoagulated.

Venous thromboembolism associated with hip and knee replacement over a ten-year period

This population-based study investigated the incidence and trends in venous thromboembolic disease after total hip and knee arthroplasty over a ten-year period. Death or readmission for venous thromboembolic disease up to two years after surgery for all patients in Scotland was the primary outcome. The incidence of venous thromboembolic disease, including fatal pulmonary embolism, three months after surgery was 2.27% for primary hip arthroplasty and 1.79% for total knee arthroplasty. The incidence of fatal pulmonary embolism within three months was 0.22% for total hip arthroplasty and 0.15% for total knee arthroplasty. The majority of events occurred after hospital discharge, with no apparent trend over the period. The data support current advice that prophylaxis should be continued for at least six weeks following surgery. Despite the increased use of policies for prophylaxis and earlier mobilisation, there has been no change in the incidence of venous thromboembolic disease.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).

Comparison of two different rehabilitation programmes for thrust plate prosthesis: a randomized controlled study

OBJECTIVE

Weight bearing after total hip arthroplasty is postponed in order to prevent early loosening, but this negatively affects the rehabilitation programme. For the force transfer characteristics of thrust plate prosthesis (TPP), a new type of hip prosthesis used without cement is similar to the normal hip. We evaluated the possibilities of early weight bearing after TPP by comparing early partial with early full weight bearing.

DESIGN

Randomized controlled study.

SETTING

Department of orthopaedics and traumatology in a university hospital.

SUBJECTS

Sixty hips of 51 patients who underwent total hip arthroplasty with TPP were randomly assigned into two groups.

INTERVENTIONS

Both groups received accelerated rehabilitation programmes: group 1 with early partial weight bearing and group 2 with early full weight bearing.

MAIN OUTCOME MEASURES

Patients were evaluated by a blind observer preoperatively, at three months after surgery by clinical (measurement of range of hip motion (universal goniometry), muscle strength (Manual Muscle Test), functional test (6-minute walk test), hip function (Harris Hip Scoring System)) and radiographical parameters and one year after surgery by clinical (Harris Hip Scoring System) and radiographical parameters.

RESULTS

Group 2 performed transfer activities earlier, had more walking distance at the time of discharge and shorter hospital stay than group 1. At three months, Harris Hip Score, muscle strength, 6-minute walk test, and duration of crutch use were significantly (p < 0.05) in favour of group 2. None of the patients in either group showed signs of loosening one year after the operation.

CONCLUSIONS

These results suggest that patients with TPP can tolerate an accelerated rehabilitation programme with early weight bearing and will gain the goals of rehabilitation earlier.

Prevention of venous thromboembolism in spinal surgery

Deep vein thrombosis (DVT), and its most feared complication, pulmonary embolism (PE), still have a high incidence with high risk for patients' health. Proven prophylactic measures are available but are generally underused, and DVT is still considered the most common cause of preventable death among hospitalized patients. The rationale for prophylaxis of venous thromboembolism is based on the clinically silent nature of the disease, the relatively high prevalence among hospitalized patients and the potentially tragic consequences of a missed diagnosis. During the last 15-20 years, spine surgery has changed radically, developing into a well-defined area of specialist surgery, and some attention is now being given to DVT events in spine surgery. The incidence of DVT during spine surgery is not documented in the literature, because only case reports or retrospective studies are reported. It would therefore be very helpful to initiate a multicenter study in order to understand this problem better and to develop, if possible, some guidelines on prophylactic measures in spine surgery. In doing so, we need to consider each patient's pattern, any risk factors and every kind of surgical technique related to DVT, in order to improve the outcome of the patient and to reduce any medicolegal problems that could arise from a thrombotic complication or an epidural hematoma, with its high potential for irreversible consequences.

Techniques for measuring weight bearing during standing and walking

OBJECTIVE

To classify and assess techniques for measuring the amount of weight bearing during standing and walking.

BACKGROUND

A large variety of weight bearing measuring techniques exists. This review describes their advantages and limitations to assist clinicians and researchers in selecting a technique for their specific application in measuring weight bearing.

METHODS

A literature search was performed in Pubmed-Medline, CINAHL, and EMBASE. Measurement techniques were classified in 'clinical examination', 'scales', 'biofeedback systems', 'ambulatory devices' and 'platforms', and assessed on aspects of methodological quality, application, and feasibility.

RESULTS

A total of 68 related articles was evaluated. The clinical examination technique is a crude method to estimate the amount of weight bearing. Scales are useful for static measurements to evaluate symmetry in weight bearing. Biofeedback systems give more reliable, accurate and objective data on weight bearing compared to clinical examination and scales, but the high costs could limit their use in physical therapy departments. The ambulatory devices can measure weight bearing with good accuracy and reliability in the hospital and at home. Platforms have the best methodological quality, but are mostly restricted to a gait laboratory, need trained personnel, and are expensive.

CONCLUSIONS

The choice of a technique largely depends upon the criteria discussed in this review; however the clinical utilisation, the research question posed, and the available budget also play a role. The new developments seen in the field of 'ambulatory devices' are aimed at extending measuring time, and improved practicality in data collection and data analysis. For these latter devices, however, mainly preliminary studies have been published about devices that are not (yet) commercially available.

Full weight bearing after non-cemented total hip replacement is compatible with satisfactory results

Two matched groups of 29 patients underwent hydroxyapatite-coated non-cemented total hip replacement. One group was started on immediate protected-weight-bearing walking and the other group was started on immediate full-weight-bearing walking. They were followed up regularly for 2 years. They were assessed with Harris hip score clinically and Engh's criteria of osteo-integration radiographically. No difference was found between the two groups. All patients had excellent clinical outcome after hip replacement, and all femoral stems were stable radiographically. Patients can walk with full weight bearing safely immediate after hydroxyapatite-coated non-cemented total hip replacement.

Revision total hip arthroplasty

Endoscopic visualization and pneumatically-powered ballistic chisels that can be used to remove cement and cementless prostheses are recent developmental improvements for revision total hip arthroplasty (THA). Use of these new tools facilitates the revision procedure, reduces tissue trauma, and may reduce surgical time. Understanding the anatomy of the hip joint, pathophysiology that leads to the need for joint replacement, and the implant selection process can assist perioperative nurses in caring for and teaching patients who require revision THA and their family members. This article describes implant choices based on the type of bone deformity present and the use of the ballistic chiseling system during revision THA. Potential postoperative complications also are described.

Prevention of venous thromboembolism

Recognition of the patient at risk and delivery of appropriate prophylaxis are imperative to reduce the incidence of VTE (including fatal PE) in hospitalized patients. This article provides estimates of risk and a summary of effective prophylaxis methods such that physicians can tailor an individual patient's prophylaxis regimen to maximize DVT risk reduction in the safest and most cost-effective manner.

Low-molecular-weight heparin: the optimal duration of prophylaxis against postoperative venous thromboembolism after total hip or knee replacement

Venous thromboembolism is a major health problem. In about 20% of cases, the initial clinical manifestation of venous thromboembolism is sudden death due to pulmonary embolism. Consequently, appropriate prophylaxis is critical in order to improve survival. Because patients with recent surgery have a 22-fold increased risk of postoperative venous thromboembolism, a large research effort has been directed toward identifying the safest and most effective prophylaxis after surgery, especially after total hip or knee replacement. While low-molecular-weight heparin is the most effective prophylaxis currently available, from 15% to 30% of hip or knee replacement patients still develop deep vein thrombosis by the time of hospital discharge, and another 25% develop new deep vein thrombosis by 3 weeks after discharge. Extended out-of-hospital low-molecular-weight heparin prophylaxis can safely reduce the prevalence of deep vein thrombosis by about 50%. However, essentially all of these thrombi are small, asymptomatic, and resolve without serious clinical sequelae. Based on one clinical trial, out-of-hospital low-molecular-weight heparin prophylaxis could reduce the incidence of symptomatic venous thromboembolism or all-cause death after discharge by a maximum of 2.2%. At current drug costs, universal out-of-hospital low-molecular-weight heparin prophylaxis is unlikely to be cost-effective. For most patients, 7 to 10 days of low-molecular-weight heparin prophylaxis is adequate. Future research should be directed at identifying patients at risk for out-of-hospital venous thromboembolism, and targeting extended prophylaxis to those at highest risk.

Predictors of rehospitalization for symptomatic venous thromboembolism after total hip arthroplasty

BACKGROUND

Recent studies have shown that symptomatic venous thromboembolism after total hip arthroplasty most commonly develops after the patient is discharged from the hospital. Risk factors associated with these symptomatic thromboembolic events are not well defined.

METHODS

Using administrative data from the California Medicare records for 1993 through 1996, we identified 297 patients 65 years of age or older who were rehospitalized for thromboembolism within three months after total hip arthroplasty. We compared demographic, surgical, and medical variables potentially associated with the development of thromboembolism in these patients and 592 unmatched controls.

RESULTS

A total of 89.6 percent of patients with thromboembolism and 93.8 percent of control patients were treated with pneumatic compression, warfarin, enoxaparin, or unfractionated heparin, alone or in combination. In addition, 22.2 percent and 29.7 percent, respectively, received warfarin after discharge. A body-mass index (the weight in kilograms divided by the square of the height in meters) of 25 or greater was associated with rehospitalization for thromboembolism, with an odds ratio of 2.5 (95 percent confidence interval, 1.8 to 3.4). In a multivariate model, the only prophylactic regimens associated with a reduced risk of thromboembolism were pneumatic compression in patients with body-mass indexes of less than 25 (odds ratio, 0.3; 95 percent confidence interval, 0.2 to 0.6) and warfarin treatment after discharge (odds ratio, 0.6; 95 percent confidence interval, 0.4 to 1.0).

CONCLUSIONS

In patients who underwent total hip arthroplasty, a body-mass index of 25 or greater was associated with subsequent hospitalization for thromboembolism. Pneumatic compression in patients with a body-mass index of less than 25 and prophylaxis with warfarin after discharge were independently protective against thromboembolism.