Safety Profile of Seven-Day Intra-articular Antibiotic Irrigation for the Treatment of Chronic Periprosthetic Joint Infection: A Prospective Randomized Phase II Comparative Study.

BACKGROUND: Systemic intravenous antimicrobials yield poor outcomes during treatment of periprosthetic joint infection due to the inability to obtain minimum biofilm eradication concentrations. This study evaluated the safety of a novel method of optimized local delivery of intra-articular antibiotics (IAAs). METHODS: This was a Phase II, multicenter, prospective randomized trial evaluating safety of a rapid (seven-day) two-stage exchange arthroplasty with IAA irrigation compared to standard two-stage exchange. The Experimental Group received irrigation using 80 mg tobramycin daily with a 2-hour soak, followed by hourly irrigation using 125 mg vancomycin with a 30-minute soak via an intramedullary irrigation device. The Control Group received an antibiotic-loaded cement spacer with vancomycin (average 8.4 g) and tobramycin (average 7.1 g, total 16 g antibiotics). Both groups received 12 weeks of systemic antibiotics following Stage 2. Safety measures included adverse events, peak vancomycin/tobramycin serum concentrations (Experimental Group), blood transfusion, and mortality. There were thirty-seven patients randomized to the Experimental Group and 39 to control. There was no difference in baseline demographics or comorbidities. RESULTS: There were no antibiotic medication-related adverse events and 2 serious adverse events related to antibiotic instillation. Of 188 vancomycin peak measurements, 69% had detectable serum level concentrations, with all concentrations well below the maximum acceptable trough threshold of 20 µg/mL. Of the 103 tobramycin peak measurements, 45% had detectable levels, with all below the maximum acceptable peak threshold of 18 to 24 µg/mL. There was no difference in blood transfused per subject (Experimental: 655 mL versus Control: 792 mL; P = .4188). There were two (2) deaths in the Experimental Group and four (4) in the control. CONCLUSIONS: The use of IAA is safe with minimal systemic antibiotic exposure. There was no difference in the rates or severity of serious adverse events between groups. Further research is being conducted to examine treatment efficacy.

Primary hip arthroscopy and conversion to total hip arthroplasty: trends and survival analysis in the Medicare population.

INTRODUCTION: With limited evidence on national incidences of hip arthroscopy in the elderly population, the current study aims to investigate trends of primary hip arthroscopies being performed in the elderly population, using the US Medicare database, and determine risk factors for conversion to total hip arthroplasty (THA). METHODS: Medicare Standard Analytic Files were queried using CPT codes to retrieve records of primary hip arthroscopies done for degenerative pathology during 2005-2014. Overall and age-stratified trends in the incidence of hip arthroscopy over time were analysed. Kaplan Meier survival curves were used to assess the overall 2-year conversion rate to a THA. Cox regression analysis was implemented to study risk factors for conversion. RESULTS: 8100 primary hip arthroscopies for degenerative pathology were performed during 2005-2014. There was a 280% increase in overall incidence of arthroscopy. The most commonly performed arthroscopic procedure was for chondroplasty and/or resection of labrum, with 4712 (58.1%) procedures. Around 18.5% patients underwent arthroplasty within 2 years after primary arthroscopy. Following Cox regression an existing diagnosis of osteoarthritis, ages 65-69, ages 70-74, and arthroscopies done in the West were associated with higher risk of conversion to THA within 2 years. Undergoing a repeat arthroscopy was not significantly associated with a higher risk of conversion. CONCLUSIONS: Despite inconclusive clinical evidence, hip arthroscopies are being increasingly used in patients older than 65 in the Medicare population. We conclude that patients in the age bracket of 65-74 years and with a pre-existing diagnosis of osteoarthritis, arthroscopy should be approached with caution.

Occupational hazards of orthopaedic surgery and adult reconstruction: A cross-sectional study.

BACKGROUND: Occupational injuries and hazards related to orthopaedic surgery are not well studied, and what is published on this topic is largely based on in vitro or in vivo animal studies. OBJECTIVES: To evaluate the self-reported prevalence of musculoskeletal (MSK) overuse disorders and other conditions among orthopaedic surgeons, especially those performing total hip (THA) or total knee arthroplasty (TKA), and report the factors placing these surgeons at higher risk for occupational health hazards. METHODS: This was a cross-sectional study of 66 currently practicing orthopaedic surgeons in the Midwestern United States. An online survey was sent to the participants, and all responses were collected anonymously. The survey consisted of 18 multiple-choice questions. RESULTS: Almost 82% of surgeons surveyed had either a musculoskeletal (MSK) overuse disorder, kidney stones, cataracts, infertility, deafness, or a combination of the above. Fifty-three percent of these respondents believed their medical conditions arose due to their job demands or exposure. A majority of the orthopaedic surgeons surveyed wanted to retire at either 60-65 years of age (31.8%) or 66-70 years of age (47%). Nearly 88% of the survey respondents believed they will be able to meet the demands of their job until their intended retirement age. The prevalence of an overuse disorder was highest for those who have been in practice for 21-30 years (100%). There was a trend toward higher rate of surgery for overuse condition in Adult Reconstruction (AR) surgeons. Rotator cuff disease was the most common MSK disorder affecting AR surgeons. CONCLUSION: A majority (>80%) of orthopaedic surgeons suffer from a musculoskeletal overuse disorder, kidney stones, cataracts, infertility, deafness, or a combination of these. A significant proportion (53%) of surgeons believe one or more of their medical conditions developed due to occupational exposure.

Robotic total knee arthroplasty: A missed opportunity for cost savings in Bundled Payment for Care Improvement initiatives?

BACKGROUND: The use of robotic total knee arthroplasty has become increasingly prevalent. Proponents of robotic total knee arthroplasty tout its potential to not only improve outcomes, but also to reduce costs compared with traditional total knee arthroplasty. Despite its potential to deliver on the value proposition, whether robotic total knee arthroplasty has led to improved outcomes and cost savings within Medicare's Bundled Payment for Care Improvement initiative remains unexplored. METHODS: Medicare beneficiaries who underwent total knee arthroplasty designated under Medicare severity diagnosis related group 469 or 470 in the year 2017 were identified using the 100% Medicare Inpatient Standard Analytic Files. Hospitals participating in the Bundled Payment for Care Improvement were identified using the Bundled Payment for Care Improvement analytic file. We calculated risk-adjusted, price-standardized payments for the surgical episode from admission through 90-days postdischarge. Outcomes, utilization, and spending were assessed relative to variation between robotic and traditional total knee arthroplasty. RESULTS: Overall, 198,371 patients underwent total knee arthroplasty (traditional total knee arthroplasty: n= 194,020, 97.8% versus robotic total knee arthroplasty: n = 4,351, 2.2%). Among the 3,272 hospitals that performed total knee arthroplasty, only 300 (9.3%) performed robotic total knee arthroplasty. Among the 183 participating in the Bundled Payment for Care Improvement, only 40 (19%) hospitals performed robotic total knee arthroplasty. Risk-adjusted 90-day episode spending was $14,263 (95% confidence interval $14,231-$14,294) among patients who underwent traditional total knee arthroplasty versus $13,676 (95% confidence interval $13,467-$13,885) among patients who had robotic total knee arthroplasty. Patients who underwent robotic total knee arthroplasty had a shorter length of stay (traditional total knee arthroplasty: 2.3 days, 95% confidence interval: 2.3-2.3 versus robotic total knee arthroplasty: 1.9 days, 95% confidence interval: 1.9-2.0), as well as a lower incidence of complications (traditional total knee arthroplasty: 3.3%, 95% confidence interval: 3.2-3.3 versus robotic total knee arthroplasty: 2.7%, 95% confidence interval: 2.3-3.1). Of note, patients who underwent robotic total knee arthroplasty were less often discharged to a postacute care facility than patients who underwent traditional total knee arthroplasty (traditional total knee arthroplasty: 32.4%, 95% confidence interval: 32.3-32.5 versus robotic total knee arthroplasty: 16.8%, 95% confidence interval 16.1-17.6). Both Bundled Payment for Care Improvement and non-Bundled Payment for Care Improvement hospitals with greater than 50% robotic total knee arthroplasty utilization had lower spending per episode of care versus spending at hospitals with less than 50% robotic total knee arthroplasty utilization. CONCLUSION: Overall 90-day episode spending for robotic total knee arthroplasty was lower than traditional total knee arthroplasty (Δ $-587, 95% confidence interval: $-798 to $-375). The decrease in spending was attributable to shorter length of stay, fewer complications, as well as lower utilization of postacute care facility. The cost savings associated with robotic total knee arthroplasty was only realized when robotic total knee arthroplasty volume surpassed 50% of all total knee arthroplasty volume. Hospitals participating in the Bundled Payment for Care Improvement may experience cost-saving with increased utilization of robotic total knee arthroplasty.

Room Traffic in Orthopedic Surgery: A Prospective Clinical Observational Study of Time of Day.

OBJECTIVE: High rates of operating room (OR) traffic may contribute to surgical air contamination and surgical site infections (SSIs). The purpose of this study was to evaluate room traffic patterns in orthopedic implant procedures to determine the frequency of door openings and if time of day had an effect on room traffic. METHODS: In 2015, OR traffic was assessed in orthopedic implant cases. Room traffic was reported as the number of door openings per minute. Counts of how many people were present in the operating room were noted in 5-minute intervals from the time of sterile case opening to dressing placement. Operative cases were observed and categorized into 3 periods (6:00-9:59, 10:00-13:59, and 14:00-17:59) to assess if time of day affected room traffic. RESULTS: Forty-six cases were observed for the present study. Among all cases, the mean room traffic rate was 35.2 openings per hour (SD, 10; range, 13.2-60.8). One-way analysis of variance revealed no statistically significant difference among groups (6:00-9:59 [n = 29], 10:00-13:59 [n = 10], and 14:00-17:59 [n = 7]) as it relates door openings per minute (room traffic rate) (P = 0.9237) or mean number of people in the OR (P = 0.3560). Pearson correlation revealed no correlation between case start time and room traffic rates (P = 0.6129, r2 = 0.0059) or between case start time and mean number of people in the OR (P = 0.3435, r2 = 0.0214). CONCLUSIONS: Room traffic rates and mean number of people in the OR do not correlate with time of day of case in orthopedic implant procedures.

Inpatient and outpatient opioid requirements after total joint replacement are strongly influenced by patient and surgical factors.

AIMS: Currently, there is no single, comprehensive national guideline for analgesic strategies for total joint replacement. We compared inpatient and outpatient opioid requirements following total hip arthroplasty (THA) versus total knee arthroplasty (TKA) in order to determine risk factors for increased inpatient and outpatient opioid requirements following total hip or knee arthroplasty. METHODS: Outcomes after 92 primary total knee (n = 49) and hip (n = 43) arthroplasties were analyzed. Patients with repeat surgery within 90 days were excluded. Opioid use was recorded while inpatient and 90 days postoperatively. Outcomes included total opioid use, refills, use beyond 90 days, and unplanned clinical encounters for uncontrolled pain. Multivariate modelling determined the effect of surgery, regional nerve block (RNB) or neuraxial anesthesia (NA), and non-opioid medications after adjusting for demographics, ength of stay, and baseline opioid use. RESULTS: TKAs had higher daily inpatient opioid use than THAs (in 5 mg oxycodone pill equivalents: median 12.0 vs 7.0; p < 0.001), and greater 90 day use (median 224.0 vs 100.5; p < 0.001). Opioid refills were more likely in TKA (84% vs 33%; p < 0.001). Patient who underwent TKA had higher independent risk of opioid use beyond 90 days than THA (adjusted OR 7.64; 95% SE 1.23 to 47.5; p = 0.01). Inpatient opioid use 24 hours before discharge was the strongest independent predictor of 90-day opioid use (p < 0.001). Surgical procedure, demographics, and baseline opioid use have greater influence on in/outpatient opioid demand than RNB, NA, or non-opioid analgesics. CONCLUSION: Opioid use following TKA and THA is most strongly predicted by surgical and patient factors. TKA was associated with higher postoperative opioid requirements than THA. RNB and NA did not diminish total inpatient or 90-day postoperative opioid consumption. The use of acetaminophen, gabapentin, or NSAIDs did not significantly alter inpatient opioid requirements.Cite this article: Bone Joint Open 2020;1-7:398-404.

Outcome reporting patterns in total knee arthroplasty: A systematic review.

BACKGROUND: Total knee arthroplasty (TKA) is one of the most effective ways to treat end-stage painful conditions of the knee. However, non-standardized reporting patterns can make quantitative analysis of patient outcomes difficult. METHODS: A systematic review of the literature was performed using keywords "total knee arthroplasty" and "total knee replacement." Randomized controlled trials (RCTs) meeting the inclusion criteria were sorted and reviewed. Type of study, outcome measures used to report their results, and the actual results were recorded. Quantitative analysis was performed. RESULTS: A total of 233 RCTs were included. There was significant variability in the reporting of short term and long term outcomes in total knee arthroplasty. The most common treatment domains in order of decreasing frequency were objective knee function, subjective knee function, perioperative complications, and pain. Range of motion was the most common outcome metric reported in all the RCTs and also was the most common metric used to assess objective knee function. The most common patient reported outcome measure used to assess postoperative function was the Knee Society Score followed by Knee Injury and Osteoarthritis Outcome Score. The Visual Analog Scale was the most common measurement tool used to assess postoperative pain. Most studies assessed patient outcomes in three treatment domains. None reported outcomes in all seven domains. CONCLUSION: There is significant variability in outcome reporting patterns in TKA literature. Most studies do not track outcomes comprehensively, with a significant minority of the RCTs tracking outcomes in only one treatment domain.

Risk Factors for Mid-Flexion Instability After Total Knee Arthroplasty: A Systematic Review.

BACKGROUND: Mid-flexion instability after total knee arthroplasty (TKA) is a clinical entity that is not well studied and one that has been associated with patient dissatisfaction and inferior outcomes. We sought to provide a comprehensive review of risk factors associated with mid-flexion instability. METHODS: A comprehensive literature search of PUBMED, EMBASE, Google Scholar, and Cochrane Library was performed using keywords "mid flexion," "instability," and "knee arthroplasty" in all possible combinations. All studies published from 2010 to 2020 in English were considered for inclusion. Research design, question studied, and outcomes were recorded for each study. Quantitative and qualitative analysis was performed. RESULTS: Eighteen articles meeting inclusion criteria were identified and reviewed. There were 5 computational studies, 5 cadaveric studies, and 8 clinical studies. There were 14 different risk factors investigated in relation to mid-flexion instability after TKA: 6 implant-related, 6 technique-related, and 2 patient-related factors. Of these risk factors, 5 had contradictory results published to date, resulting in an inconclusive association with mid-flexion instability. The results of this review suggest that the effects of joint line elevation and radius-of-curvature of the femoral component on mid-flexion instability are inconclusive while articular surface conformity and preoperative joint laxity may play a bigger role than previously thought. CONCLUSION: Mid-flexion instability after TKA is a clinical entity distinct from other established forms of instability. There are patient-related, implant-related, and technique-related factors associated with mid-flexion instability. The majority of the evidence on this topic is derived from computational and cadaveric studies, underscoring the need for further clinical studies.

Nerve Injuries with the Direct Anterior Approach to Total Hip Arthroplasty.

* While no single approach for total hip arthroplasty (THA) has been proven to be superior to others in terms of patient outcomes, the direct anterior approach (DAA) is becoming increasingly popular. * All of the described techniques for THA carry a small risk of nerve injury. * Identifying risk factors for nerve injury and mitigating these risks where feasible are imperative in order to reduce the incidence of this complication with any approach for THA.

Review of Guidelines for Dental Antibiotic Prophylaxis for Prevention of Endocarditis and Prosthetic Joint Infections and Need for Dental Stewardship.

Dentists prescribe 10% of all outpatient antibiotic prescriptions, writing more than 25.7 million prescriptions per year. Many are for prophylaxis in patients with prosthetic joint replacements; the American Dental Society states that "in general," prophylactic antibiotics are not recommended to prevent prosthetic joint infections. Orthopedic surgeons are concerned with the risk of implant infections following a dental procedure and, therefore, see high value and low risk in recommending prophylaxis. Patients are "stuck in the middle," with conflicting recommendations from orthopedic surgeons (OS) and dentists. Unnecessary prophylaxis and fear of lawsuits amongst private practice dentists and OS has not been addressed. We review The American Heart Association/American College of Cardiology, American Dental Association, and American Association of Orthopedic Surgeons' guidelines on dental antibiotic prophylaxis for the prevention of endocarditis and prosthetic joint infections. We provide experience on how to engage private-practice dentists and OS in dental stewardship using a community-based program.

Does Surgeon Volume Affect Outcomes Following Primary Total Hip Arthroplasty? A Systematic Review.

BACKGROUND: Surgeon volume has been identified as an important factor impacting postoperative outcome in patients undergoing orthopedic surgeries. With an absence of a detailed systematic review, we sought to collate evidence on the impact of surgeon volume on postoperative outcomes in patients undergoing primary total hip arthroplasty. METHODS: PubMed (MEDLINE) and Google Scholar databases were queried for articles using the following search criteria: ("Surgeon Volume" OR "Provider Volume" OR "Volume Outcome") AND ("THA" OR "Total hip replacement" OR "THR" OR "Total hip arthroplasty"). Studies investigating total hip arthroplasty being performed for malignancy or hip fractures were excluded from the review. Twenty-eight studies were included in the final review. All studies underwent a quality appraisal using the GRADE tool. The systematic review was performed in accordance with the PRISMA guidelines. RESULTS: Increasing surgeon volume was associated with a shorter length of stay, lower costs, and lower dislocation rates. Studies showed a significant association between an increasing surgeon volume and higher odds of early-term and midterm survivorship, but not long-term survivorships. Although complications were reported and recorded differently in studies, there was a general trend toward a lower postoperative morbidity with regard to complications following surgeries by a high-volume surgeon. CONCLUSION: This systematic review shows evidence of a trend toward better postoperative outcomes with high-volume surgeons. Future prospective studies are needed to better determine long-term postoperative outcomes such as survivorship before healthcare policies such as regionalization and/or equal-access healthcare systems can be considered.

Tranexamic acid use during total hip arthroplasty: A single center retrospective analysis.

BACKGROUND: Tranexamic acid (TXA) is an antifibrinolytic agent that has shown promise in reducing blood loss during total hip arthroplasty (THA). Several studies have reported side effects of high-dose TXA administration, including myocardial infarction (MI), thromboembolic events, and seizures. These possible side effects have prevented the widespread adoption of TXA in the surgical community. METHODS: We conducted a retrospective chart review of 564 primary and revision THAs performed at a single academic center. Surgical patients received either no TXA or 1 g IV TXA at the beginning of surgery followed by a second bolus just before the surgical wound closure, at the surgeon's discretion. We analyzed differences in hemoglobin (Hb), hematocrit (Hct), estimated blood loss (EBL), and adverse events in patients receiving TXA versus patients not receiving TXA up to 2 days following surgery. RESULTS: Significantly higher Hb and Hct values were found across all time points among patients undergoing primary posterior or revision THA who had received TXA. In addition, transfusion rates were significantly decreased in both primary posterior THAs and revision THAs when TXA was administered. Patients who received TXA experienced significantly fewer adverse events than those who did not for all surgery types. CONCLUSION: Administration of low-dose intravenous (IV) and intra-articular (IA) TXA does not appear to increase rates of adverse events and may be effective in minimizing blood loss, as reflected by Hb and Hct values following THA.

Perioperative Allogeneic Red Blood-Cell Transfusion Associated with Surgical Site Infection After Total Hip and Knee Arthroplasty.

BACKGROUND: Perioperative allogeneic red blood-cell transfusion is a suspected risk factor for surgical site infection (SSI) after total joint arthroplasty (TJA), but the interrelationships among SSI risk, transfusion dose, preoperative anemia, and the presence of coagulopathies have not been well described. METHODS: Data on SSI within 1 year after surgery as well as on transfusion with blood products within 30 days after surgery were obtained for 6,788 patients who had undergone primary or revision total hip or knee arthroplasty from 2000 to 2011 in a single hospital system. Multivariate logistic regression modeling was used to determine the independent association between allogeneic red blood-cell transfusion and SSI. RESULTS: There was a dose-dependent association between allogeneic red blood-cell transfusion and SSI, with the infection rate increasing as the transfusion dose increased from 1 unit (odds ratio [OR] = 1.97; 95% confidence interval [CI] = 1.38, 2.79; p < 0.001), to 2 units (OR = 2.20; CI = 1.37, 3.44; p = 0.002), to 3 units (OR = 3.66; CI = 1.72, 7.16; p = 0.001), and to >3 units (OR = 7.40; CI = 4.91, 11.03; p < 0.001) after controlling for medical comorbidities, planned procedure, preoperative anemia, and preexisting coagulopathies. A preexisting bleeding disorder (OR = 2.09; CI = 1.57, 2.80; p < 0.001) and clotting disorder (OR = 1.37; CI = 1.14, 1.64; p = 0.001) and preoperative anemia (OR = 3.90; CI = 3.31, 4.61; p < 0.001) were all independent risk factors for transfusion after adjusting for the planned procedure. CONCLUSIONS: We found a dose-dependent relationship between allogeneic red blood-cell transfusion and SSI risk after total hip or knee arthroplasty. Additionally, preoperative anemia or a known bleeding or clotting disorder were risk factors for the need for allogeneic red blood-cell transfusion. Our findings underscore the need for preoperative risk assessment, methods to limit surgical tissue injury, and optimized blood conservation strategies. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Catastrophic failure of an acetabular total hip arthroplasty component mimicking a posterior dislocation.

In our case study, we examine a case of catastrophic failure of a total hip arthroplasty acetabular component leading to complete central wear by the ceramic femoral head, requiring revision total hip arthroplasty. Despite subtle clinical findings, initial orthopaedic evaluation and treatment yielded a diagnosis of total hip arthroplasty dislocation. While a much more common phenomenon, the diagnosis led to futile initial attempts at closed reduction. Our index of suspicion must remain high to pick up on subtle, less common diagnoses we will encounter.

Acute Kidney Disease After Total Hip and Knee Arthroplasty: Incidence and Associated Factors.

BACKGROUND: The development of acute kidney disease (AKD) following total joint arthroplasty has not been well characterized in the literature. We sought to calculate the incidence and identify risk factors associated with postoperative AKD for patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). METHODS: A total of 1000 consecutive cases (860 unique patients, including revisions) of TKA or THA performed between January 2010 and May 2016 were identified. Seventy-nine cases were excluded due to pre-existing kidney dysfunction and 23 additional cases were excluded due to incomplete data, resulting in 898 cases included in the study. There were 492 females and 406 males with a mean age of 58.1 years (range, 14-93 years). The Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease criteria and serum creatinine values were used to determine AKD status. Multiple logistic regression modeling was used to identify postoperative AKD risk factors. RESULTS: Overall incidence of postoperative AKD was 6.8% (n = 61). Use of perioperative angiotensin receptor blocker (ARBs) or angiotensin-converting enzyme inhibitors (ACEi) (odds ratio [OR] = 2.09; P = .030), increasing body mass index (BMI) (OR = 1.58 per 10 kg/m2; P = .014), and use of vancomycin perioperatively (OR = 1.91; P = .021) were associated with increased odds of development of postoperative AKD. CONCLUSION: A 6.8% incidence rate of postoperative AKD was noted in patients undergoing TKA or THA. Perioperative use of ARBs/ACEi, perioperative vancomycin use, and increased BMI were associated with increased odds of postoperative AKD.

Relationships between varus-valgus laxity of the severely osteoarthritic knee and gait, instability, clinical performance, and function.

Increased varus-valgus laxity has been reported in individuals with knee osteoarthritis (OA) compared to controls. However, the majority of previous investigations may not report truly passive joint laxity, as their tests have been performed on conscious participants who could be guarding against motion with muscle contraction during laxity evaluation. The purpose of this study was to investigate how a measure of passive knee laxity, recorded when the participant is under anesthesia, is related to varus-valgus excursion during gait, clinical measures of performance, perceived instability, and self-reported function in participants with severe knee OA. We assessed passive varus-valgus knee laxity in 29 participants (30 knees) with severe OA, as they underwent total knee arthroplasty (TKA). Participants also completed gait analysis, clinical assessment of performance (6-min walk (6 MW), stair climbing test (SCT), isometric knee strength), and self-reported measures of function (perceived instability, Knee injury, and Osteoarthritis Outcome Score (KOOS) a median of 18 days before the TKA procedure. We observed that greater passive varus-valgus laxity was associated with greater varus-valgus excursion during gait (R2 = 0.34, p = 0.002). Significant associations were also observed between greater laxity and greater isometric knee extension strength (p = 0.014), farther 6 MW distance (p = 0.033) and shorter SCT time (p = 0.046). No relationship was observed between passive varus-valgus laxity and isometric knee flexion strength, perceived instability, or any KOOS subscale. The conflicting associations between laxity, frontal excursion during gait, and functional performance suggest a complex relationship between laxity and knee cartilage health, clinical performance, and self-reported function that merits further study. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1644-1652, 2017.

Development and Validation of a Preoperative Surgical Site Infection Risk Score for Primary or Revision Knee and Hip Arthroplasty.

BACKGROUND: Surgical site infection (SSI) is a major complication following total joint arthroplasty. Host susceptibility to infection has emerged as an important predictor of SSI. The purpose of this study was to develop and validate a preoperative SSI risk-assessment tool for primary or revision knee and hip arthroplasty. METHODS: Data for 6,789 patients who underwent total joint arthroplasty (from the years 2000 to 2011) were obtained from a single hospital system. SSI was defined as a superficial infection within 30 days or deep infection within 1 year. Logistic regression modeling was utilized to create a risk scoring system for a derivation sample (n = 5,789; 199 SSIs), with validation performed on a hold-out sample (a subset of observations chosen randomly from the initial sample to form a testing set; n = 1,000; 41 SSIs). RESULTS: On the basis of logistic regression modeling, we created a scoring system to assess SSI risk (range, 0 to 35 points) that is the point sum of the following: primary hip arthroplasty (0 points); primary knee (1); revision hip (3); revision knee (3); non-insulin-dependent diabetes (1); insulin-dependent diabetes (1.5); chronic obstructive pulmonary disease (COPD) (1); inflammatory arthropathy (1.5); tobacco use (1.5); lower-extremity osteomyelitis or pyogenic arthritis (2); pelvis, thigh, or leg traumatic fracture (2); lower-extremity pathologic fracture (2.5); morbid obesity (2.5); primary bone cancer (4); reaction to prosthesis in the last 3 years (4); and history of staphylococcal septicemia (4.5). The risk score had good discriminatory capability (area under the ROC [receiver operating characteristic] curve = 0.77) and calibration (Hosmer-Lemeshow chi-square test, p = 0.34) and was validated using the independent sample (area under the ROC curve = 0.72). A small subset of patients (5.9%) had a >10% estimated infection risk. CONCLUSIONS: The patient comorbidities composing the risk score heavily influenced SSI risk for primary or revision knee and hip arthroplasty. We believe that infection risk can be objectively determined in a preoperative setting with the proposed SSI risk score.