Elective Primary Total Knee Research Articles

Risk factors for urinary retention after hip or knee replacement: a cohort study

IntroductionIn 2006, our provincial government initiated a program to reduce wait times for total hip or knee replacements by referring patients to a single tertiary-care centre. This program provided an opportunity to identify risk factors for perioperative complications as part of a continuing quality improvement project. We report the risk of postoperative urinary retention after hip and knee replacements and the risk factors associated with this complication.MethodsAfter local Research Ethics Board approval, data were abstracted from charts of patients who underwent elective primary unilateral total hip or knee replacement surgery. The outcome was urinary retention in the first 24 hr after surgery. Risk factors were identified using multivariable logistic regression, and they were expressed as odds ratios (OR) or 95% confidence intervals (CI).ResultsFrom April 1, 2006 to May 31, 2007, 1,440 patients underwent 1,515 elective total hip replacement or total knee replacement. We abstracted data from 1,031 (71.3%) patients: mean age, 62 yr (interquartile range [IQR] 55-70); 53.7% female; 605 total hip replacements; and 426 total knee replacements. The procedures were performed under spinal (81.8%), general (10.2%), or combined spinal and general (8.0%) anesthesia. Patients spent 100 [IQR 90-114] min in the operating room and 3 [IQR 3-4] days in hospital. The 24-hr incidence of urinary retention was 43.3% (446/1031). Male sex (odds ratio [OR] 3.9; 95% CI 3.0 to 5.2), total hip replacement (OR 1.4; 95% CI 1.1 to 1.9), and intrathecal morphine were risk factors.DiscussionPostoperative urinary retention is a common complication after total hip or total knee replacement, especially amongst men and patients receiving intrathecal morphine.

Smoking as a risk factor for short‐term outcomes following primary total hip and total knee replacement in veterans

To assess the effect of smoking on postoperative complications following elective primary total hip replacement (THR) or primary total knee replacement (TKR). We used data from the national Veterans Affairs Surgical Quality Improvement Program to examine the association of smoking status at surgery with 30-day postoperative complication rates (including surgical site and other infections, pneumonia, stroke, myocardial infarction, mortality, and other complications) in veterans undergoing primary elective THR or TKR. Multilevel multivariable-adjusted logistic regression models, adjusted for age, race/ethnicity, work relative value units, American Society of Anesthesiology classification, and year of surgery, with additional adjustment for wound classification for surgical site infections, were used. A total of 33,336 patients, 95% men and 80% white with a mean age of 64 years, underwent elective primary THR/TKR between October 2001 and September 2008. Fifty-seven percent never smoked, 19% were prior smokers, and 24% were current smokers. Current smokers undergoing THR/TKR were significantly more likely than never smokers to have surgical site infections (odds ratio [OR] 1.41, 95% CI 1.16-1.72), pneumonia (OR 1.53, 95% CI 1.10-2.14), stroke (OR 2.61, 95% CI 1.26-5.41), and 1-year mortality (OR 1.63, 95% CI 1.31-2.02). Prior smokers were significantly more likely than nonsmokers to have pneumonia, (OR 1.34, 95% CI 1.00-1.80), stroke (OR 2.14, 95% CI 1.12-4.10), and urinary tract infection (OR 1.26, 95% CI 1.02-1.55). Current smoking at the time of elective THR or TKR is associated with increased postarthroplasty complications, especially surgical site infections and pneumonia. Preoperative smoking cessation programs should be considered in patients undergoing elective THR or TKR.

Strategies for reducing transfusions in major orthopaedic surgery.

Strategies for reducing transfusions in major orthopaedic surgery.

Perioperative Hyperglycemia and Postoperative Infection after Lower Limb Arthroplasty

One of the most serious complications after major orthopedic surgery is deep wound or periprosthetic joint infection. Various risk factors for infection after hip and knee replacement surgery have been reported, including patients' comorbidities and surgical technique factors. We investigated whether hyperglycemia and diabetes mellitus (DM) are associated with infection that requires surgical intervention after total hip and knee arthroplasty. We reviewed our computerized database for elective primary total hip and knee arthroplasty from 2000 to 2008. Demographic information, past medical history of patients, perioperative biochemistry, and postoperative complications were reviewed. Patients were divided into two groups: infected group (101 patients who had surgical intervention for infection at our institution within 2 years after primary surgery) and noninfected group (1847 patients with no intervention with a minimum of one year follow-up. The data were analyzed using t, chi-squared, and Fisher's exact tests. There were significantly more diabetes patients in the infected group compared with the noninfected group (22% versus 9%, p < .001). Infected patients had significantly higher perioperative blood glucose (BG) values: preoperative BG (112 ± 36 versus 105 ± 31 mg/dl, p = .043) and postoperative day (POD) 1 BG (154 ± 37 versus 138 ± 31 mg/dl, p < .001). Postoperative morning hyperglycemia (BG >200 mg/dl) increased the risk for the infection more than two-fold. Non-DM patients were three times more likely to develop the infection if their morning BG was >140 mg/dl on POD 1, p = .001. Male gender, higher body mass index, knee arthroplasty, longer operative time and hospital stay, higher comorbidity index, history of myocardial infarction, congestive heart failure, and renal insufficiency were also associated with the infection. Diabetes mellitus and morning postoperative hyperglycemia were predictors for postoperative infection following total joint arthroplasty. Even patients without a diagnosis of DM who developed postoperative hyperglycemia had a significantly increased risk for the infection.

Post-discharge pain management following elective primary total hip and total knee arthroplasty on patients discharged to home on pod 5 or earlier from an acute care facility

Summary This study explores the patient experience of post-operative pain management after discharge home from hospital following primary Total Joint Arthroplasty (TJA) on post-operative day 5 or earlier. The aims of the study were to determine pain scores of participants, assess patient's satisfaction, the amount of prescribed analgesic tablets taken in the first 5days post-discharge and assess the association between pain scores and the number of tablets taken, controlling for age and gender. Patients were given a Pain Self Assessment Form and asked to complete it for five days after discharge. Eighty-five out of 98 eligible patients returned their survey by mail. Results indicated that participants who had a right total knee arthroplasty had the highest pain scores (4.4/10) and used the most analgesics. Sixty-nine percent of participants reported that they were satisfied with their level of pain from Post-Operative Day (POD) 5–9. Females were less satisfied and consumed more analgesics. Participants younger than 65years of age reported lower pain scores and used more analgesics.

Autologous transfusion of drain contents in elective primary knee arthroplasty: its value and relevance.

Total knee arthroplasty is associated with significant post-operative blood loss often necessitating blood transfusions. Blood transfusions may be associated with transfusion reactions and may transmit human immunodeficiency virus, hepatitis C virus and hepatitis B virus, with devastating consequences. After total knee arthroplasty, transfusion of the contents of an autologous drain is becoming common practice. The aim of our study was to look at the effectiveness of these drains in elective primary total knee arthroplasty. A prospective study was conducted including 70 non-randomised patients. A normal suction drain was used in 35 patients (group A), whereas in the other 35 patients, a CellTrans™ drain was used (group B). All the operations were performed by four surgeons using a tourniquet with a medial parapatellar approach. Pre- and post-operative haemoglobin concentrations were recorded in both groups. A Student's t-test was applied to determine the statistical significance of the data collected. The average fall in post-operative haemoglobin was 3.66 g/dL (SD 1.46; range, 0.6-7.0) among patients in whom the simple drain was used (group A) and 2.29 g/dL (SD 0.92; range, 0.6-5.9) among those in whom the CellTrans™ drain was used (group B) (p<0.0001). Twenty-five units of allogeneic blood were required in group A compared to four units in group B. The rate of transfusion was 5.7% (2 patients) in the group in which CellTrans™ drain was used and 25.7% (9 patients) in the group in which a simple suction drain was used. Total knee arthroplasty is associated with significant post-operative blood loss despite best operative technique. Autologous reinfusion of the contents of a CellTrans™ drain significantly reduces the rate of post-operative blood transfusion. This study indicates that the use of an autologous drain could be recommended as routine practice in primary total knee arthroplasty.

Patient preferences before and after total knee arthroplasty

Objective Patients before total joint arthroplasty vary in the spectrum and importance of their concerns. The objectives of this study were to evaluate the psychometric properties of the Knee Patient-Specific Index (KPSI) and to determine the type and importance of patients' concerns before and after knee arthroplasty. Study Design and Setting A cohort of 119 patients scheduled for elective primary (or revision) total knee arthroplasty were interviewed at two tertiary care teaching hospitals. Patients also completed the Knee Society Scale (KSS), the Short Form 36, the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and the McMaster Toronto Arthritis Patient Preference Disability Questionnaire (MACTAR). Results Patients improved after total knee arthroplasty in all 42 symptoms and physical limitations, except crouching/kneeling and walking up and down stairs. Patients' summated concerns correlated with the WOMAC pain subscale (ranging from 0.72 to 0.79), WOMAC physical function subscale (ranging from 0.72 to 0.76), and KSS (ranging from 0.28 to 0.39). The summated responses changed after knee arthroplasty as demonstrated by the standardized response mean of 1.1. Conclusions The KPSI captures individual patient unique preferences for patients undergoing total knee arthroplasty. Patients improved in virtually all aspects of their symptoms and function after surgery, with the exception of crouching/kneeling and knee feeling hot.

Comparación de la eficacia y seguridad de tres técnicas analgésicas (epidural, bloqueo femoral y bloqueo femoral-ciático) en el postoperatorio de prótesis total de rodilla

Pain after total knee replacement surgery is intense. The aim of this study was to compare 3 techniques for providing postoperative analgesia (epidural analgesia, femoral nerve block, and a combined femoral-sciatic nerve block) in total knee arthroplasty. Observational study of 1550 elective primary unilateral total knee replacement operations. The safety and efficacy of the following 3 techniques were compared: epidural analgesia, femoral nerve block, and femoral-sciatic nerve block. Demographic, anesthetic, and surgical data were recorded. Study variables included pain intensity on a visual analog scale every 4 hours, need for rescue analgesia (morphine), complications and adverse events within 5 postoperative days. No significant differences were found in demographic, anesthetic, or surgical variables. In the first 24 hours after surgery, pain intensity was significantly less for patients who received a femoral-sciatic nerve block. The mean levels of morphine consumption in the first 96 hours after surgery were similar in the femoral-sciatic nerve block group (3.18 mg) and the epidural analgesia group (3.19 mg); morphine consumption in the femoral block group was significantly higher (4.51 mg). Epidural analgesia was associated with the highest rate of complications (17%). A sciatic nerve block combined with a femoral nerve block attenuates pain more effectively and is associated with less postoperative morphine consumption in comparison with a femoral nerve block alone. Peripheral nerve block techniques have fewer adverse side effects than epidural analgesia.

Inpatient Compared with Home-Based Rehabilitation Following Primary Unilateral Total Hip or Knee Replacement: A Randomized Controlled Trial

Home-based rehabilitation is increasingly utilized to reduce health-care costs; however, with a shorter hospital stay, the possibility arises for an increase in adverse clinical outcomes. We evaluated the effectiveness and cost of care of home-based compared with inpatient rehabilitation following primary total hip or knee joint replacement. We randomized 234 patients, using block randomization techniques, to either home-based or inpatient rehabilitation following total joint replacement. All patients followed standardized care pathways and were evaluated, with use of validated outcome measures (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], Short Form-36, and patient satisfaction), prior to surgery and at three and twelve months following surgery. The primary outcome was the WOMAC function score at three months after surgery. The mean length of stay (and standard deviation) in the acute care hospital was 6.3 +/- 2.5 days for the group designated for inpatient rehabilitation prior to transfer to that facility compared with 7.0 +/- 3.0 days for the home-based rehabilitation group prior to discharge home (p = 0.06). The mean length of stay in inpatient rehabilitation was 17.7 +/- 8.6 days. The mean number of postoperative home-based rehabilitation visits was eight. The prevalence of postoperative complications up to twelve months postoperatively was similar in both groups, which each had a 2% rate of dislocation and a 3% rate of clinically important deep venous thrombosis. The prevalence of infection was 0% in the home-based group and 2% in the inpatient group. None of these differences was clinically important. Both groups showed substantial improvements at three and twelve months, with no significant differences between the groups with respect to WOMAC, Short Form-36, or patient satisfaction scores (p > 0.05). The total episode-of-care costs (in Canadian dollars) for the inpatient rehabilitation and home-based rehabilitation arms were $14,532 and $11,082, respectively (p < 0.01). Despite concerns about early hospital discharge, there was no difference in pain, functional outcomes, or patient satisfaction between the group that received home-based rehabilitation and the group that had inpatient rehabilitation. On the basis of our findings, we recommend the use of a home-based rehabilitation protocol following elective primary total hip or knee replacement as it is the more cost-effective strategy.

Effectiveness of accelerated perioperative care and rehabilitation intervention compared to current intervention after hip and knee arthroplasty. A before-after trial of 247 patients with a 3-month follow-up

BackgroundIn Denmark, approximately 12,000 hip and knee arthroplasties were performed in 2006, and the hospital costs were close to US$ 110,000,000. In a randomized clinical trial, we have recently demonstrated the efficacy of accelerated perioperative care and rehabilitation intervention after hip and knee arthroplasty compared to current intervention under ideal circumstances. We do not, however, know whether these results could be reached under usual circumstances of healthcare practice. We therefore investigated whether length of stay after implementation of accelerated perioperative care and rehabilitation after hip and knee arthroplasty could be reduced in a normal healthcare setting, and how the achieved results matched those observed during the randomized clinical trial.MethodsAn effectiveness study as a before-after trial was undertaken in which all elective primary total hip and total knee arthroplasty patients were divided into a before-implementation group receiving the current perioperative procedure, and an after-implementation group receiving the new accelerated perioperative care and rehabilitation procedures as provided by a new multi-disciplinary organization. We used the Breakthrough Series Collaborative Model for implementation. The primary outcome measure was in hospital length of stay (LOS), and the secondary outcome measure was adverse effects within 3 months postoperatively.ResultsWe included a total of 247 patients. Mean LOS was significantly (P < 0.001) reduced by 4.4 (95% CI 3.8–5.0) days after implementation of the accelerated intervention, from 8.8 (SD 3.0) days before implementation to 4.3 (SD 1.8) days after implementation. No significant differences in adverse effects were observed. LOS in this effectiveness study was significantly lower than LOS reported in the efficacy study.ConclusionAccelerated perioperative care and rehabilitation intervention after hip and knee arthroplasty was successfully and effectively implemented. Results obtained during usual hospital circumstances matched the results achieved under ideal circumstances in this group of patients.

Short-term beneficial effects of physiotherapy exercise after knee arthroplasty for osteoarthritis

What are the effects of physiotherapy exercise for patients with osteoarthritis after elective primary unilateral total knee arthroplasty? AMED, CINAHL, EMBASE, King's Fund, Medline, Cochrane library, PEDro, and the UK Department of Health national research register, searched up to April 2007. This search was supplemented by handsearching a small number of journals and conference abstracts, as well as scanning the reference lists from relevant articles identified by the search. Randomised controlled trials involving patients undergoing elective total knee arthroplasty for osteoarthritis in which organised physiotherapy after discharge from hospital was compared to standard post-discharge management. Outcome measures were function, range of motion, muscle strength, walking speed, and quality of life. : Two reviewers (masked to the key details of the papers) independently assessed methodological quality on a checklist developed from the CONSORT statement and the Critical Appraisal Skills Programme guidelines and extracted the data. Six trials with a total of 614 patients were identified, of which five trials with a total of 554 patients provided data that could be included in the meta-analyses. Trial quality was good overall. The trials compared additional physiotherapy exercises or treatment after discharge with no organised outpatient physiotherapy. The patients in the control groups were expected to continue with traditional home exercise programs: isometric strengthening, range of movement exercises, and gait training. Based on quantitative pooling of three trials at 3 to 4 months follow up, there were statistically significant differences in favour of physiotherapy exercises for function (standardised effect size 0.33, 95% CI 0.07 to 0.58) and range of motion (weighted mean difference 3 degrees, 95% CI 1 to 5). At the same time point, results from two trials indicated no significant difference in quality of life (weighted mean difference 1.7 points, 95% CI −1 to 4.3) or walking speed (standardised effect size 0.27 (95% CI –0.13 to 0.67). None of the trials measured muscle strength. At one year follow up, there were no statistically significant differences in any outcome. Additional physiotherapy exercises or treatment after discharge have small to moderate short-term beneficial effects compared to no organised outpatient physiotherapy.

Comparison of the relative analgesic efficacies of epidural or intramuscular diamorphine following total knee arthroplasty

Debate has proliferated as to the true site of action of opioids when placed in the epidural space. The aim of this study was to compare the analgesic effects of a bolus of diamorphine given by the epidural or intramuscular route. Sixty patients having elective primary total knee replacements were recruited and randomized to receive epidural or intramuscular diamorphine. A lumbar epidural catheter was sited and 10 mL of bupivacaine 0.5% wt vol-1 was injected. Patients subsequently received diamorphine 5 mg into the epidural space or as an intramuscular injection. Patient-controlled analgesia with intravenous morphine was used for postoperative analgesia. The primary outcome measures included time to first patient-controlled analgesia use and total morphine consumption in 24 h. Secondary end-points considered possible treatment complications. All primary end-points showed significant differences in favour of epidural diamorphine. Medians for times to first patient-controlled analgesia use and total 24 h morphine requirements were significantly different (P < 0.001) at 418 vs. 198 min and 11 vs. 39 mg, respectively. There were no significant differences in secondary end-points. This study has shown the superior analgesic efficacy of epidural diamorphine when compared to intramuscular injection.

Effectiveness of physiotherapy exercise after knee arthroplasty for osteoarthritis: systematic review and meta-analysis of randomised controlled trials

Objective To evaluate the effectiveness of physiotherapy exercise after elective primary total knee arthroplasty in patients with osteoarthritis.Design Systematic review.Data sources Database searches: AMED, CINAHL, Embase, King's Fund, Medline, Cochrane...

Antibiotic Dosing Before Primary Hip and Knee Replacement as a Pay-for-Performance Measure

Background: There is a trend toward linking the reimbursement for health care services to clinical outcome. One such pay-for-performance proposal that affects orthopaedic surgeons is linking reimbursement for hip and knee replacements to measures such as the percentage of patients receiving antibiotics before surgery. We analyzed the risk factors associated with failing to optimally administer preoperative antibiotics before primary hip and knee arthroplasty. Methods: Data on 988 elective primary total hip and knee replacements done at one institution were collected. Multivariate analysis was performed to determine clinical factors associated with administration of antibiotics outside the recommended window (within one hour before the incision). Results: Thirteen percent of the patients did not receive optimal antibiotic therapy (within the one-hour window prior to the elective arthroplasty). Five patients (0.5%) received no documented preoperative antibiotics. Patients undergoing total hip arthroplasty were more likely to receive antibiotics outside the one-hour window than were patients undergoing total knee arthroplasty. Longer induction times were associated with administration of antibiotics outside the one-hour window. Certain individual surgeons and anesthesiologists were more likely to administer antibiotics on time. The anesthesiologist effect was more significant than the surgeon effect. Conclusions: Approximately 13% of the patients did not receive optimal antibiotic therapy before total hip and knee replacement. Surgeons can improve their performance score for this measure by focusing antibiotic strategies on patients receiving a hip replacement and on complex cases, by developing systems for antibiotic dosing with the anesthesia team, and by improving documentation.

Antibiotic Dosing Before Primary Hip and Knee Replacement as a Pay-for-Performance Measure

There is a trend toward linking the reimbursement for health care services to clinical outcome. One such pay-for-performance proposal that affects orthopaedic surgeons is linking reimbursement for hip and knee replacements to measures such as the percentage of patients receiving antibiotics before surgery. We analyzed the risk factors associated with failing to optimally administer preoperative antibiotics before primary hip and knee arthroplasty. Data on 988 elective primary total hip and knee replacements done at one institution were collected. Multivariate analysis was performed to determine clinical factors associated with administration of antibiotics outside the recommended window (within one hour before the incision). Thirteen percent of the patients did not receive optimal antibiotic therapy (within the one-hour window prior to the elective arthroplasty). Five patients (0.5%) received no documented preoperative antibiotics. Patients undergoing total hip arthroplasty were more likely to receive antibiotics outside the one-hour window than were patients undergoing total knee arthroplasty. Longer induction times were associated with administration of antibiotics outside the one-hour window. Certain individual surgeons and anesthesiologists were more likely to administer antibiotics on time. The anesthesiologist effect was more significant than the surgeon effect. Approximately 13% of the patients did not receive optimal antibiotic therapy before total hip and knee replacement. Surgeons can improve their performance score for this measure by focusing antibiotic strategies on patients receiving a hip replacement and on complex cases, by developing systems for antibiotic dosing with the anesthesia team, and by improving documentation.

Comparison of Analgesic Methods for Total Knee Arthroplasty: Metabolic Effect of Exogenous Glucose

This study was set up to assess whether postoperative suppression of gluconeogenesis by dextrose infusion would be influenced by continuous peripheral nerve block (CPNB) with local anesthetics, in comparison with epidural and with intravenous analgesia. Twenty-seven patients, undergoing elective primary total knee arthroplasty for osteoarthritis, were randomly allocated to one of the three groups of 9 patients each: patient controlled analgesia (PCA) with i.v. morphine, epidural with bupivacaine 0.1% and fentanyl 3mug/ml, or continuous femoral and sciatic blocks with ropivacaine 0.2%. Endogenous glucose production, an index of gluconeogenesis, and glucose clearance, an index of whole body glucose uptake, were assessed on the second postoperative day by measuring [6,6-(2)H(2)]glucose kinetics after an overnight fast (fasted state), and during a 3-h period infusion of dextrose at 4 mg/kg/min (fed state). Visual analog scale (VAS) at rest and at knee flexion, use of morphine, mobilization, nutritional intake, and bowel function were also collected. Endogenous glucose production was totally suppressed by 3 h of dextrose infusion in all 3 groups (P < .001) while glucose clearance was unchanged. Blood glucose and insulin increased (P < .001), while glucagon decreased, with the greatest change in the epidural group (P < .05). VAS at rest and at knee flexion was significantly lower in patients receiving epidural and CPNB compared to i.v. morphine (P < .05). Restoration of bowel function, assessed as return of bowel movements, was faster in the CPNB group (P < .05). Excellent analgesia was achieved in the epidural and continuous nerve block groups. Postoperative gluconeogenesis was totally suppressed by dextrose infusion independent of the analgesia technique with no change in glucose utilization.

Valores plasmáticos de proteína C reactiva (PCR) en cirugía ortopédica electiva

C reactive protein (CRP) is used as a marker of inflammatory, infectious and surgical processes. To measure post operative plasma CRP levels after elective orthopedic surgery. Four groups of 25 patients each were defined according to the type of surgical procedure performed. Group I corresponded to pure arthroscopic meniscectomy. Group II to arthroscopic anterior cruciate ligament reconstruction or knee osteotomy. Group III to elective primary total hip or knee arthroplasty and group IV to instrumented elective spine surgery. Plasma CRP levels were measured prospectively at the preoperative day and at the 1st, 2nd, 3rd, 7th and 15th postoperative day. Patients that had any complication were evaluated independently. In all uncomplicated patients, a similar shape and distribution of plasma CRP curves were observed, with maximum postoperative levels observed between the second and third day. Patients with more complex surgical procedures had higher CRP values. In all groups, CRP levels decreased significantly at 7th and 15th day, with respect to the higher measured value. In patients with surgical complications, PCR values were higher or did not decrease significantly at the seventh postoperative day, as in patients without complications. Plasma CRP levels fluctuate after elective orthopedic surgical procedures, with maximum values observed between the 2nd and 3rd postoperative day followed by an ulterior decrease. This behavior changes if postoperative complication appear. Serial measurements of CRP levels may be useful in the early detection of surgical complications.

Epidemiology of Total Knee Replacement in the United States Medicare Population

There are limited population-based data on the utilization and outcomes of total knee replacement. The aim of the present study was to describe the rates of primary and revision total knee replacement and selected outcomes in persons older than sixty-five years of age in the United States. Using Medicare claims, we computed annual incidence rates of unilateral elective primary and revision total knee replacement among United States Medicare beneficiaries in the year 2000. Poisson regression was used to assess the relationships between demographic characteristics and the incidence rates of primary and revision knee replacement. Proportional hazards models were used to examine the relationships between the ninety-day rates of complications and demographic and clinical factors. The rate of primary knee replacement was lower in blacks than in whites and in those qualifying for Medicaid supplementation than in those with higher incomes. The complications observed during the ninety days following primary knee replacement included mortality (0.7%), readmission (0.9%), pulmonary embolus (0.8%), wound infection (0.4%), pneumonia (1.4%), and myocardial infarction (0.8%). The complications observed during the ninety days following revision knee replacement were mortality (1.1%), readmission (4.7%), pulmonary embolus (0.5%), wound infection (1.8%), pneumonia (1.4%), and myocardial infarction (1.0%). Blacks had higher rates of mortality, readmission, and wound infection after primary knee replacement than whites did. Patients who qualified for Medicaid supplementation had higher complication rates, particularly after primary knee replacement. Overall, the rates of postoperative complications during the ninety days following total knee replacement are low. In the United States, blacks and individuals with low income undergo total knee replacement less frequently and generally have higher rates of adverse outcomes following primary knee replacement.

EPIDEMIOLOGY OF TOTAL KNEE REPLACEMENT IN THE UNITED STATES MEDICARE POPULATION

Background: There are limited population-based data on the utilization and outcomes of total knee replacement. The aim of the present study was to describe the rates of primary and revision total knee replacement and selected outcomes in persons older than sixty-five years of age in the United States. Methods: Using Medicare claims, we computed annual incidence rates of unilateral elective primary and revision total knee replacement among United States Medicare beneficiaries in the year 2000. Poisson regression was used to assess the relationships between demographic characteristics and the incidence rates of primary and revision knee replacement. Proportional hazards models were used to examine the relationships between the ninety-day rates of complications and demographic and clinical factors. Results: The rate of primary knee replacement was lower in blacks than in whites and in those qualifying for Medicaid supplementation than in those with higher incomes. The complications observed during the ninety days following primary knee replacement included mortality (0.7%), readmission (0.9%), pulmonary embolus (0.8%), wound infection (0.4%), pneumonia (1.4%), and myocardial infarction (0.8%). The complications observed during the ninety days following revision knee replacement were mortality (1.1%), readmission (4.7%), pulmonary embolus (0.5%), wound infection (1.8%), pneumonia (1.4%), and myocardial infarction (1.0%). Blacks had higher rates of mortality, readmission, and wound infection after primary knee replacement than whites did. Patients who qualified for Medicaid supplementation had higher complication rates, particularly after primary knee replacement. Conclusions: Overall, the rates of postoperative complications during the ninety days following total knee replacement are low. In the United States, blacks and individuals with low income undergo total knee replacement less frequently and generally have higher rates of adverse outcomes following primary knee replacement. Level of Evidence: Prognostic Level II. See Instructions to Authors for a complete description of levels of evidence.

ASSOCIATION BETWEEN HOSPITAL AND SURGEON PROCEDURE VOLUME AND THE OUTCOMES OF TOTAL KNEE REPLACEMENT

The annual volume of major cardiovascular and oncologic procedures performed in hospitals and by surgeons has been inversely associated with the rates of perioperative mortality and complications. The relationship between hospital and surgeon volume and perioperative outcomes following total knee replacement has received little study. We analyzed claims data for Medicare patients who had elective primary total knee replacement between January 1 and August 31, 2000. Hospital and surgeon volumes were defined as the number of primary and revision total knee replacements performed in the hospital or by the surgeon in Medicare recipients in 2000. We examined the associations between the annual volumes of total knee replacement performed in the hospitals and by the surgeons and the rates of mortality and complications (infection, pulmonary embolus, myocardial infarction, or pneumonia) in the first ninety days postoperatively. The analyses were adjusted for age, gender, comorbid conditions, Medicaid eligibility (a marker of low income), and arthritis diagnosis. Analyses of hospital volume were adjusted for surgeon volume and vice versa. Twenty-five percent of the primary total knee replacements were done by surgeons who performed twelve of these procedures or fewer in the Medicare population annually, and 11% were done in hospitals with an annual volume of twenty-five of these procedures or fewer. Compared with the patients who had a primary total knee replacement in hospitals with an annual volume of twenty-five procedures or fewer, those managed in hospitals with an annual volume exceeding 200 procedures had a lower risk of pneumonia (odds ratio, 0.65; 99% confidence interval, 0.47 to 0.90) and any of the adverse outcomes examined (death, pneumonia, pulmonary embolus, acute myocardial infarction, or deep infection) (odds ratio, 0.74; 99% confidence interval, 0.60 to 0.90). Similarly, patients who had a primary total knee replacement done by surgeons who performed more than fifty such procedures in Medicare recipients annually had a lower risk of pneumonia (odds ratio, 0.72; 99% confidence interval, 0.54 to 0.95) and any adverse outcome (odds ratio, 0.81; 99% confidence interval, 0.68 to 0.98) compared with patients of surgeons with an annual volume of twelve procedures or fewer. Patients managed at hospitals and by surgeons with greater volumes of total knee replacement have lower risks of perioperative adverse events following primary total knee replacement. Patients and clinicians should incorporate these findings into discussions about selecting a surgeon and a hospital for total knee replacement. These data should also be integrated into the policy debate about the advantages and drawbacks of regionalizing total joint replacement to high-volume centers.