Therapeutic evaluation of immunomodulators in reducing surgical wound infection.

Despite many advances in infection control practices, including prophylactic antibiotics, surgical site infections (SSIs) remain a significant cause of morbidity, prolonged hospitalization, and death worldwide. Our innate immune system possesses a multitude of powerful antimicrobial strategies which make it highly effective in combating bacterial, fungal, and viral infections. However, pathogens use various stealth mechanisms to avoid the innate immune system, which in turn buy them time to colonize wounds and damage tissues at surgical sites. We hypothesized that immunomodulators that can jumpstart and activate innate immune responses at surgical sites, would likely reduce infection at surgical sites. We used three immunomodulators; fMLP (formyl-Methionine-Lysine-Proline), CCL3 (MIP-1α), and LPS (Lipopolysaccharide), based on their documented ability to elicit strong inflammatory responses; in a surgical wound infection model with Pseudomonas aeruginosa to evaluate our hypothesis. Our data indicate that one-time topical treatment with these immunomodulators at low doses significantly increased proinflammatory responses in infected and uninfected surgical wounds and were as effective, (or even better), than a potent prophylactic antibiotic (Tobramycin) in reducing P. aeruginosa infection in wounds. Our data further show that immunomodulators did not have adverse effects on tissue repair and wound healing processes. Rather, they enhanced healing in both infected and uninfected wounds. Collectively, our data demonstrate that harnessing the power of the innate immune system by immunomodulators can significantly boost infection control and potentially stimulate healing. We propose that topical treatment with these immunomodulators at the time of surgery may have therapeutic potential in combating SSI, alone or in combination with prophylactic antibiotics.

Randomized Trial of Static and Articulating Spacers for Treatment of the Infected Total Hip Arthroplasty.

BACKGROUND: The purpose of this randomized clinical trial is to compare perioperative and postoperative variables between static and articulating spacers for the treatment of chronic periprosthetic joint infection (PJI) complicating total hip arthroplasty (THA). METHODS: Fifty-two patients undergoing resection arthroplasty as part of a 2-stage exchange for PJI at 3 centers were randomized to either a static (n = 23) or articulating spacer (n = 29). The primary endpoint was operative time of the second-stage reimplantation and power analysis determined that 22 patients per cohort were necessary to detect a 20-minute difference. Seven patients were lost to follow-up, 4 were never reimplanted, and one died before discharge after reimplantation. Forty patients were followed for a mean 3.2 years (range 2.0-7.1). RESULTS: There were no differences in operative time at second-stage reimplantation (143 minutes static vs 145 minutes articulating, P = .499). Length of hospital stay was longer in the static cohort after stage 1 (8.6 vs 5.4 days, P = .006) and stage 2 (6.3 vs 3.6 days, P < .001). Although it did not reach statistical significance with the numbers available for study, nearly twice as many patients in the static cohort were discharged to an extended care facility after stage 1 (65% vs 30%, P = .056). CONCLUSION: This randomized trial demonstrated that the outcomes of static and articulating spacers are similar in the treatment of THA PJI undergoing 2-stage exchange arthroplasty. The significantly longer length of hospital stay associated with the use of static spacers may have important economic implications for the health care system.

Implementation of a risk-stratified approach to prevent postoperative nausea and vomiting in an institution with high baseline rates of prophylaxis.

BACKGROUND AND AIMS: Although a risk-adjusted approach to preventing postoperative nausea and vomiting (PONV) is generally recommended, the successful implementation of such practice without mandated protocols remains elusive. To date, such a strategy has never been adapted to curb high baseline rates of prophylaxis. MATERIAL AND METHODS: We conducted an observational study on a cohort of patients undergoing elective surgery before and after the implementation of a quality improvement initiative including a risk-stratified approach to prevent PONV. The primary outcome was the number of prophylactic interventions administered. Secondary outcome included the repetition of ineffective medications and the need for rescue medication in the post-anesthesia care unit (PACU). RESULTS: A total of 636 patients were included; 325 patients during the control period and 311 after the intervention. The educational program failed to reduce the amount of prophylactic antiemetics administered (2.0 vs. 2.6, P < 0.001) and the repeat administration of ineffective medications for rescue (16% vs. 20%, P = 0.15). More patients in the intervention group required rescue medication compared to the control group (16.9% vs. 9.7%; P = 0.04). CONCLUSION: Implementation of best practices to combat PONV remains elusive. Our results indicate that difficulties in changing provider behavior also apply to institutions with high prophylactic antiemetic administration rates.

Early Treatment With Metformin in a Mice Model of Complex Regional Pain Syndrome Reduces Pain and Edema.

BACKGROUND: Metformin, an adenosine monophosphate (AMP)-activated protein kinase activator, as well as a common drug for type 2 diabetes, has previously been shown to decrease mechanical allodynia in mice with neuropathic pain. The objective of this study is to determine if treatment with metformin during the first 3 weeks after fracture would produce a long-term decrease in mechanical allodynia and improve a complex behavioral task (burrowing) in a mouse tibia fracture model with signs of complex regional pain syndrome. METHODS: Mice were allocated into distal tibia fracture or nonfracture groups (n = 12 per group). The fracture was stabilized with intramedullary pinning and external casting for 21 days. Animals were then randomized into 4 groups (n = 6 per group): (1) fracture, metformin treated, (2) fracture, saline treated, (3) nonfracture, metformin treated, and (4) nonfracture, saline treated. Mice received daily intraperitoneal injections of metformin 200 mg/kg or saline between days 14 and 21. After cast removal, von Frey force withdrawal (every 3 days) and burrowing (every 7 days) were tested between 25 and 56 days. Paw width was measured for 14 days after cast removal. AMP-activated protein kinase downregulation at 4 weeks after tibia fracture in the dorsal root ganglia was examined by immunohistochemistry for changes in the AMP-activated protein kinase pathway. RESULTS: Metformin injections elevated von Frey thresholds (reduced mechanical allodynia) in complex regional pain syndrome mice versus saline-treated fracture mice between days 25 and 56 (difference of mean area under the curve, 42.5 g·d; 95% CI of the difference, 21.0-63.9; P < .001). Metformin also reversed burrowing deficits compared to saline-treated tibial fracture mice (difference of mean area under the curve, 546 g·d; 95% CI of the difference, 68-1024; P < .022). Paw width (edema) was reduced in metformin-treated fracture mice. After tibia fracture, AMP-activated protein kinase was downregulated in dorsal root ganglia neurons, and mechanistic target of rapamycin, ribosomal S6 protein, and eukaryotic initiation factor 2α were upregulated. CONCLUSIONS: The important finding of this study was that early treatment with metformin reduces mechanical allodynia in a complex regional pain syndrome model in mice. Our findings suggest that AMP-activated protein kinase activators may be a viable therapeutic target for the treatment of pain associated with complex regional pain syndrome.

High Failure at a Minimum 5-Year Follow-Up in Primary Total Hip Arthroplasty Using a Modular Femoral Trunnion.

BACKGROUND: Modular femoral trunnions enable the surgeon to independently adjust offset, leg length, and anteversion in total hip arthroplasty (THA). However, modularity may result in an increased risk of fretting and corrosion along with a higher risk of implant dissociation or fracture. The purpose of this study is to evaluate mid-term survivorship of THAs using a cementless modular system. METHODS: A consecutive series of 221 patients who underwent a primary THA using the ALFA II modular stem by a single surgeon between 2002 and 2004 were reviewed. Survivorship of the ALFA II modular hip system was evaluated at a minimum of 5 years postoperatively. RESULTS: Of the 221 patients, 28 (12.7%) died from causes unrelated to the surgery before adequate follow-up, and 64 (29.0%) patients were lost to follow-up. The remaining 129 patients had a mean 6.5-year (range: 5-8 years) follow-up. All-cause survivorship of the modular stem system was 81% (95% confidence interval = 69-90) at a mean 6.5-year follow-up. Of the 25 (19.4%) cases requiring revision surgery, 52.0% was for dissociation of the modular components, 32.0% was for fracture of the prosthesis, 12.0% was for instability/multiple dislocations, and 4.0% was for chronic septic THA. Body mass index (odds ratio = 1.080) and offset (odds ratio = 1.254) were independent risk factors for mechanical failures of the modular stem system. CONCLUSION: The modular stem hip system of interest in this study demonstrates a high failure rate at mid-term follow-up, and we caution against the use of similar designs in primary THAs.

Oral Ketamine for Acute Pain Management After Amputation Surgery.

Objective: Intravenous ketamine has been shown to provide postoperative analgesia in many clinical trials, in particular to reduce opioid consumption. The primary objective of this pilot study is to determine if multiple dosing over a three-day perioperative period with oral ketamine is a safe treatment method for acute pain after amputation surgery. Methods: Three consented subjects (age 57-60 years) undergoing elective amputation of the lower extremity were included in the study (Institutional Review Board and Food and Drug Administration Investigational New Drug approved). An analgesic dose of oral ketamine (1.0 mg/kg) was administered one hour before surgery. Eight hours after the preoperative dose, a second dose was given. On the first postoperative day, subjects received oral ketamine (1.0 mg/kg) three times per day; and on the second postoperative day, this dose was reduced to 0.5 mg/kg three times per day. The primary outcome measure was the incidence of adverse events. Results: No serious and unexpected adverse events occurred; therefore, no subject required a dose reduction. The numerical rating score for postoperative pain of the body part adjacent to the amputation site ranged from 0.5-4.0. Morphine milligram equivalent opioid doses were in the range of 0-17.5 mg on the first postop day and 1.0-4.0 mg on the second postop day. Conclusions: Our pilot study suggests that oral ketamine is safe to use at 1 mg/kg three times per day, as well as convenient for hospital floor and potential home use. Future studies will determine if the perioperative oral ketamine also reduces the incidence of chronic stump or phantom limb pain.

Incidence and Changing Trends of Shoulder Stabilization in the United States.

PURPOSE: To determine the incidence and demographic characteristics of shoulder stabilization in the United States, with particular focus on age, sex, and inpatient versus outpatient treatment. METHODS: The National Hospital Discharge Survey and the National Survey of Ambulatory Surgery databases were searched using a combination of International Classification of Diseases, Ninth Revision diagnosis and procedure codes, encompassing open and arthroscopic shoulder stabilization procedures. Incidence was determined using National Survey of Ambulatory Surgery, National Hospital Discharge Survey, and US census data, and the results were stratified by age, sex, facility, and concomitant diagnoses. Data were analyzed between 1994 and 2006, the most recent year for which data are available within these sources. RESULTS: The incidence of shoulder stabilization in the United States was 5.84 per 100,000 person-years (n = 15,514; 95% confidence interval, 11,975-19,053) in 1994 to 1996 and 6.89 per 100,000 person-years (n = 20,588; 95% confidence interval, 16,254-24,922) in 2006 (P = .0697). The number of inpatient procedures decreased significantly whereas the number of outpatient procedures increased significantly over the same period (P < .0001 for both). The incidence of stabilization increased in patients aged 45 to 64 years (P < .0001) and patients aged 65 years or older (P = .0008) but was unchanged in patients aged 44 years or younger (P = .4745). The average age of patients undergoing stabilization increased over the study period, from 30 years to 47 years for inpatients (P = .01) and from 27 years to 34 years for ambulatory patients (P = .05). The incidence of stabilization increased significantly in male patients (P = .0075) but remained stable in female patients (P = .8057) over the same period. Diagnoses related to rotator cuff pathology and shoulder derangement were the most common concurrent diagnosis codes. CONCLUSIONS: The overall incidence of shoulder stabilization in the United States is 6.89 per 100,000 person-years. The incidence increased by 18% between 1994 and 2006. During the study period, shoulder stabilization shifted to become a largely outpatient procedure, and the average age increased significantly. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Continuous Adductor Canal Blocks Provide Superior Ambulation and Pain Control Compared to Epidural Analgesia for Primary Knee Arthroplasty: A Randomized, Controlled Trial.

BACKGROUND: Adductor canal blocks (ACBs) are an alternative to femoral nerve blocks that minimize lower extremity weakness. However, it is unclear whether this block will provide analgesia that is equivalent to techniques, such as epidural analgesia. The purpose of this randomized controlled trial was to compare continuous ACBs with epidural analgesia for primary total knee arthroplasty. METHODS: Following institutional review board approval, 145 patients were randomized to 1 of 3 groups: combined spinal-epidural (CSE), spinal + continuous ACB (CACB), or general + CACB. Epidural analgesia was used postoperatively in the CSE group, and an adductor canal catheter was used in the CACB groups. Power analysis determined that 84 patients per group were needed to demonstrate a 35% increase in ambulation with an alpha of 0.05 at a power of 90%. RESULTS: At interim analysis, 13 patients were removed for protocol deviations, leaving 45 in CSE, 41 in spinal + CACB and 46 in general + CACB groups. Patient demographics were similar in all comparisons suggesting appropriate randomization. Patients in the CACB groups walked further on postoperative day 1, 2, and 3 (P = .02). Mean daily pain scores were lower in the CACB groups (4.1 CSE, 3.0 spinal + CACB, 3.4 general + CACB, P = .009). There was no significant difference in total opioid consumption between groups (158 morphine equivalents CSE, 149 spinal + CACB, and 172 general + CACB). More patients reported being "very satisfied" in CACB groups (68% general + CACB, 63% spinal + CACB, and 36% CSE; P = .001). CONCLUSION: Continuous adductor analgesia provides superior ambulation, lower pain scores, faster discharge, and greater patient satisfaction when compared to epidural analgesia for primary total knee arthroplasty.

The Mark Coventry, MD, Award: Oral Antibiotics Reduce Reinfection After Two-Stage Exchange: A Multicenter, Randomized Controlled Trial.

BACKGROUND: Many patients develop recurrent periprosthetic joint infection after two-stage exchange arthroplasty of the hip or knee. One potential but insufficiently tested strategy to decrease the risk of persistent or recurrent infection is to administer additional antibiotics after the second-stage reimplantation. QUESTIONS/PURPOSES: (1) Does a 3-month course of oral antibiotics decrease the risk of failure secondary to infection after a two-stage exchange? (2) Are there any complications related to the administration of oral antibiotics after a two-stage exchange? (3) In those patients who develop a reinfection, is the infecting organism different from the initial infection? METHODS: Patients at seven centers randomized to receive 3 months of oral antibiotics or no further antibiotic treatment after operative cultures after the second-stage reimplantation were negative. Adult patients undergoing two-stage hip or knee revision arthroplasty for a periprosthetic infection who met Musculoskeletal Infection Society (MSIS) criteria for infection at the first stage were included. Oral antibiotic therapy was tailored to the original infecting organism(s) in consultation with an infectious disease specialist. MSIS criteria as used by the treating surgeon defined failure. Surveillance of patients for complications, including reinfection, occurred at 3 weeks, 6 weeks, 3 months, 12 months, and 24 months. If an organism demonstrated the same antibiotic sensitivities as the original organism, it was considered the same organism; no DNA subtyping was performed. Analysis was performed as intent to treat with all randomized patients included in the groups to which they were randomized. A log-rank survival curve was used to analyze the primary outcome of reinfection. At planned interim analysis (enrollment is ongoing), 59 patients were successfully randomized to the antibiotic group and 48 patients to the control group. Fifty-seven patients had an infection after TKA and 50 after a THA. There was no minimum followup for inclusion in this analysis. The mean followup was 14 months in the antibiotic group and 10 months in the control group. RESULTS: Patients treated with oral antibiotics failed secondary to infection less frequently than those not treated with antibiotics (5% [three of 59] versus 19% [nine of 48]; hazard ratio, 4.37; 95% confidence interval, 1.297-19.748; p = 0.016). Three patients had an adverse reaction to the oral antibiotics severe enough to cause them to stop taking the antibiotics early, and four patients who were randomized to that group did not take the antibiotics as directed. With the numbers available, there were no differences between the study groups in terms of the likelihood that an infection after treatment would be with a new organism (eight of nine in the control group versus one of three in the treatment group, p = 0.087). CONCLUSIONS: This multicenter randomized trial suggests that at short-term followup, the addition of 3 months of oral antibiotics appeared to improve infection-free survival. As a planned interim analysis, however, these results may change as the study reaches closure and the safety profile may yet prove risky. Further followup of this cohort of patients will be necessary to determine whether these preliminary results are durable over time. LEVEL OF EVIDENCE: Level I, therapeutic study.

Aseptic Lymphocytic-Dominated Vasculitis-Associated Lesions Scores Do Not Correlate With Metal Ion Levels or Unreadable Synovial Fluid White Blood Cell Counts.

BACKGROUND: Failed metal-on-metal (MoM) bearings are being increasingly encountered with little information to guide evaluation for aseptic lymphocytic-dominated vasculitis-associated lesions (ALVAL). It is often assumed that elevated metal ion levels correlate with the occurrence of ALVAL. Our purpose was to determine the utility of the erythrocyte sedimentation rate, C-reactive protein, synovial white blood cell count, differential (%PMN), and serum metal ion levels in diagnosing ALVAL. METHODS: We identified 80-failed MoM total hip arthroplasties. Tissue was examined under light microscopy and graded on a scale of ALVAL severity. Mean laboratory values were compared between groups and receiver operating curves generated with an area under the curve to determine test performance and optimal cutoffs. RESULTS: ALVAL scores were graded as low in 30 (37.5%), moderate in 39 (49%), and severe in 8 (10%), with 3 being unreadable. No clear cutoff values for erythrocyte sedimentation rate, C-reactive protein, or synovial white blood cell count could be determined to reliably diagnose moderate or severe ALVAL. Furthermore, serum metal levels had no correlation with ALVAL score. The best test to diagnose ALVAL was the synovial fluid monocyte percentage with an optimal cutoff value of 39% and area under the curve of 69% (moderate testing performance). CONCLUSION: The diagnosis of ALVAL remains challenging, with most of the screening tests being unreliable. Although serum metal ion levels are typically elevated in failed MoM bearings, higher levels do not appear to correlate with ALVAL grade. Elevated synovial fluid monocytes may provide diagnostic utility for ALVAL, suggesting a possible delayed-type hypersensitivity reaction.

Is There a Benefit to Head Size Greater Than 36 mm in Total Hip Arthroplasty?

This study compares the rate of dislocation and revision for instability between 36-mm and anatomic femoral heads (large diameter metal-on-metal THA, dual-mobility bearings, and hip resurfacing arthroplasty) in patients at high risk for dislocation. A total of 501 high-risk patients, over a 10-year period, were identified (282 36-mm THA, 24 dual-mobility bearings, 83 metal-on-metal arthroplasty, and 112 hip resurfacing arthroplasty). There were 13 dislocations in the 36-mm group compared to 1 in the anatomic group (4.6% vs 0.5%; P = .005). Four patients dislocated more than once in the 36-mm group (1.4% vs 0%; P = .04), and 2 patients in the 36-mm group required a revision for instability (0.7% vs 0%; P = .11). These results suggest that anatomic head sizes significantly lower the risk of dislocation in high-risk patients.

Diagnosing Infection in the Setting of Periprosthetic Fractures.

BACKGROUND: The diagnosis of periprosthetic joint infection is particularly challenging in patients with periprosthetic fractures. The purpose of this study was to investigate the utility of commonly used diagnostic tests for periprosthetic joint infection in patients with a periprosthetic fracture. METHODS: Of 121 patients treated with a periprosthetic fracture (97 hips, 24 knees, mean age: 72.9), 14 (11.6%) met Musculoskeletal Infection Society criteria for infection. Diagnostic variables were evaluated using logistic regression models for the prediction of infection and receiver operating characteristics curves. RESULTS: The synovial white blood cell (WBC) count and differential were the best diagnostic tests, with good test performance (area under the curve, 84%) and optimal cutoffs of 2707 WBC/uL and 77% polymorphonuclear cells. The erythrocyte sedimentation rate and C-reactive protein were found to have overall lower test performance but remained relatively sensitive at standard cutoff values of 30 mm/h and 10 mg/L, respectively. CONCLUSION: The synovial fluid WBC count and differential are the best tests with optimal cutoff values that are similar to those used for patients without a periprosthetic fracture.

The James A. Rand Young Investigator's Award: A Randomized Controlled Trial of Oral and Intravenous Tranexamic Acid in Total Knee Arthroplasty: The Same Efficacy at Lower Cost?

BACKGROUND: Tranexamic acid (TXA) is a synthetic antifibrinolytic agent successfully used intravenously (IV) to reduce blood loss after total knee arthroplasty (TKA). An oral formulation of the medication is available, at a fraction of the cost of the IV preparation. The purpose of this randomized controlled trial is to determine if oral TXA is equivalent to IV TXA in reducing blood loss in TKA. METHODS: In this double-blinded, placebo-controlled trial, patients undergoing primary TKA were randomized to receive 1.95g of TXA orally 2 hours preoperatively or 1g IV bolus before wound closure. The primary outcome was reduction of hemoglobin. Power analysis determined that 30 patients were required in each group. Equivalence analysis was performed with pooled and Satterthwaite t tests with a P-value of <.05 suggesting equivalence between treatments. RESULTS: Thirty-four patients received oral TXA and 37 patients received IV TXA. There was no difference in the mean reduction of hemoglobin between oral and IV groups (3.45g/dL vs 3.31g/dL, respectively; P = .001, equivalence), and total blood loss was equivalent at 1281 mL vs 1231 mL, respectively (P = .02, equivalence). One patient in each group was transfused. CONCLUSION: Oral TXA provides equivalent reductions in blood loss, at a cost of $14 compared with $47-$108 depending on the IV formulation selected. As approximately 700,000 primary TKA are performed in the United States annually, a switch to oral TXA could yield total cost savings of between $23 million and $67 million dollars per year for our health care system.

The Incidence and Severity of Postoperative Pain following Inpatient Surgery.

OBJECTIVE: In recent years, there has been increased attention to pain management after surgery in the hospital setting along with financial enticement from the US government. The aim of this study is to evaluate the current efficacy of postoperative pain management. METHODS: In a prospective study, patients in an academic private nonprofit medical center were asked the same questions about their postoperative pain as in a previously published 2003 survey. Questionnaires on 1) pain intensity on a verbal categorical scale and 2) patient satisfaction with pain medication were completed in the patient's room before hospital discharge, and followed-up by telephone interviews at 1 and 2 weeks later. Numerical Pain Scale (NRS) pain scores were obtained at the same time points. Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) results for pain management were obtained at bedside interview along with standard mailed HCAHPS survey obtained by Press Ganey. RESULTS: Based on 441 surgical inpatients (Orthopedic, General, Neurosurgery, Gynecological) 12% of patients had "Severe-to-Extreme" pain and 54% had "Moderate-to-Extreme" pain at discharge. During the first 2 weeks after discharge, 13% of patients had "Severe-to-Extreme" pain and 46% had "Moderate-to-Extreme" pain. Pain scores at discharge and after discharge were negatively correlated with patient satisfaction with pain medication (P < 0.0001), indicating that increased pain intensity was associated with decreased patient satisfaction. For the HCAHPS question "how often was your pain well controlled?," 66% answered "Always" in the Press Ganey report versus 51% at bedside (P < 0.0001). CONCLUSIONS: The incidence of severe-to-extreme pain in patients before and after discharge following inpatient surgery is 12-13%, and this is a reduction from 10 years ago.

Short-term glycemic control is effective in reducing surgical site infection in diabetic rats.

BACKGROUND: Patients and animals with diabetes exhibit enhanced vulnerability to bacterial surgical infections. Despite multiple retrospective studies demonstrating the benefits associated with glycemic control in reducing bacterial infection after cardiac surgery, there are fewer guidelines on the use of glycemic control for noncardiac surgeries. In the current study, we investigated whether long-term (begun 2 weeks before surgery) or immediate (just before surgery) glycemic controls, continued postoperatively, can reduce surgical site infection in type 1 diabetic-induced rats. METHODS: Rats were injected with streptozotocin to induce type 1 diabetes. Four groups of animals underwent surgery and thigh muscle Staphylococcus aureus bacteria challenge (1 × 10 colony forming units) at the time of surgery. Group 1 diabetic rats received insulin treatment just before surgery and continued until the end of study (short-term glycemic control group). Group 2 diabetic rats received insulin treatment 2 weeks before surgery and continued until the end of study (long-term glycemic control). Group 3 diabetic rats received no insulin treatment (no glycemic control group). Group 4 nondiabetic rats served as a healthy control group. Rats were euthanized at 3 or 6 days after surgery. Blood glucose and muscle bacterial burden were measured at 3 or 6 days after surgery. RESULTS: Glycemic control was achieved in both long- and short-term insulin-treated diabetic rats. Compared with untreated diabetic rats, the bacterial burden in muscle was significantly lower in both groups of glycemic controlled diabetic rats at 3 (all P < 0.003) and 6 (all P < 0.0001) days after surgery. CONCLUSIONS: A short-term glycemic control regimen, initiated just before surgery and bacterial exposure, was as effective in reducing surgical site infection as a long-term glycemic control in type 1 diabetic rats. These data suggest that immediately implementing glycemic control in type 1 diabetic surgical patients before undergoing noncardiac surgery may decrease the risk of infection.

Is potential malnutrition associated with septic failure and acute infection after revision total joint arthroplasty?

BACKGROUND: Although malnutrition has been hypothesized to increase the risk of periprosthetic joint infection (PJI), strong evidence linking the two is lacking. QUESTIONS/PURPOSES: The purposes of this study were to determine (1) if one or more laboratory values suggestive of malnutrition is independently associated with being revised for an infected joint arthroplasty as opposed to for an aseptic failure; (2) the relationship between laboratory parameters suggestive of malnutrition and obesity; and (3) if one or more laboratory parameters suggestive of malnutrition is independently associated with acute PJI complicating an aseptic revision procedure. METHODS: Between 2002 and 2010, one surgeon performed 600 revision total joint arthroplasties in 547 patients; during that time, nutritional parameters (including serum albumin, total lymphocyte count, and transferrin) were routinely obtained preoperatively; complete data sets were available on 454 patients (501 procedures [84%]). We compared the frequency of having one or more laboratory parameters suggestive of malnutrition between patients undergoing a revision for septic reasons and aseptic reasons as well as between obese and nonobese patients. The 375 aseptic revisions were then assessed for the incidence of acute postoperative infection (within 90 days, diagnosed with Musculoskeletal Infection Society criteria). Multivariate logistic regression modeling was used to evaluate factors independently associated with (1) a septic as opposed to an aseptic mode of failure; and (2) acute postoperative infection after an aseptic revision. RESULTS: Patients in 67 of 126 (53%) revisions for PJI had one or more laboratory parameters suggestive of malnutrition compared with 123 of 375 (33%) undergoing revision for a noninfectious etiology (odds ratio [OR], 2.3 [95% confidence interval, 1.5-3.5]; p<0.001). Patients who were of normal weight at the time of revision had the highest frequency of laboratory parameters suggestive of malnutrition (42 of 82 [51%]), although this was common in obese patients as well (76 of 238 [32%]) (p=0.002). Among the 375 aseptic revisions, 12 developed an acute postoperative infection (3%). The frequency of infection was nine of 123 in the group having one or more laboratory parameters suggestive of malnutrition and three of 252 in the group not having such laboratory parameters (7% versus 1%; p=0.003). Multivariate regression revealed that having laboratory parameters suggestive of malnutrition is independently associated with both chronic PJI (p=0.003; OR, 2.1) and an acute postoperative infection complicating an aseptic revision arthroplasty (p=0.02; OR, 5.9). CONCLUSIONS: Having one or more laboratory parameters suggestive of malnutrition is common among patients undergoing revision arthroplasty and is independently associated with both chronic septic failure and acute postoperative infection complicating a revision performed for a noninfectious etiology. Future studies should assess the impact of a standardized screening protocol with subsequent correction of abnormal laboratory parameters suggestive of malnutrition on the risk of PJI to determine a potential causal relationship between the two. LEVEL OF EVIDENCE: Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Do serologic and synovial tests help diagnose infection in revision hip arthroplasty with metal-on-metal bearings or corrosion?

BACKGROUND: The diagnosis of periprosthetic joint infection (PJI) in patients with failed metal-on-metal (MoM) bearings and corrosion reactions in hip arthroplasties can be particularly difficult, because the clinical presentation of adverse local tissue reactions may mimic that of PJI, because it can also occur concurrently with PJI, and because common laboratory tests used to diagnose PJI may be elevated in patients with MoM THAs. QUESTIONS/PURPOSES: We sought to determine the test properties of the serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), synovial fluid white blood cell (WBC) count, and synovial fluid differential (percent polymorphonuclear cells [PMNs]) in diagnosing PJI in either MoM hips undergoing revision for a variety of indications or in non-MoM hips undergoing revision for either corrosion reaction or full-thickness wear. Additionally, we sought to describe how MoM bearings, metal debris, and corrosion reactions can confound the analysis of the synovial fluid WBC count and affect its diagnostic use for PJI. METHODS: We reviewed 150 revision hips meeting specified inclusion criteria (92 MoM total hips, 19 MoM hip resurfacings, 30 non-MoM bearings with corrosion, and nine full-thickness bearing surface wear with metallosis). In our review, we diagnosed 19 patients as infected using Musculoskeletal Infection Society (MSIS) criteria. Mean laboratory values were compared between infected and not infected patients and receiver operator characteristic curves were generated with an area under the curve (AUC) to determine test performance and optimal cutoffs. RESULTS: After excluding the inaccurate synovial fluid samples, the synovial fluid WBC count (performed accurately in 102 patients) was the best test for the diagnosis of PJI (AUC=98%, optimal cutoff 4350 WBC/µL) followed by the differential (performed accurately in 102 patients; AUC=90%, optimal cutoff 85% PMN). The ESR (performed in 131 patients) and CRP (performed in 129 patients) both had good sensitivity (83% and 94%, respectively). Patients meeting MSIS criteria for PJI had higher mean serum ESR, CRP, synovial fluid WBC count, and differential than those not meeting MSIS criteria (p<0.05 for all). An observer blinded to the MSIS diagnosis of the patient assessed the synovial fluid samples for inaccuracy secondary to metal or cellular debris. Synovial fluid sample "inaccuracy" was defined as the laboratory technician noting the presence of metal or amorpous material, fragmented cells, or clots, or the sample having some defect preventing an automated cell count from being performed. Of the 141 patients who had a synovial fluid sample initially available for review, 47 (33%) had a synovial fluid sample deemed to be inaccurate. A synovial fluid WBC count was still reported; however, 35 of these 47 hips (75%) and 11 of these 35 (31%) were falsely positive for infection. CONCLUSIONS: The diagnosis of PJI is extremely difficult in patients with MoM bearings or corrosion and the synovial fluid WBC count can frequently be falsely positive and should be relied on only if a manual count is done and if a differential can be performed. A more aggressive approach to preoperative evaluation for PJI is recommended in these patients to allow for careful evaluation of the synovial fluid specimen, the integration of synovial fluid culture results, and repeat aspiration if necessary. LEVEL OF EVIDENCE: Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Is synovial C-reactive protein a useful marker for periprosthetic joint infection?

BACKGROUND: Serum C-reactive protein (CRP) is a general marker of inflammation, and recent studies suggest that measurement of CRP in synovial fluid may be a more accurate method for diagnosing periprosthetic joint infection (PJI). QUESTIONS/PURPOSES: We aimed to (1) determine if there is a correlation between serum and synovial CRP values, (2) establish cutoff values for diagnosing infection based on serum and synovial CRP, and (3) compare the utility of measuring CRP in synovial fluid versus serum for the diagnosis of PJI using standard assay equipment available at most hospitals. METHODS: Between February 2011 and March 2012, we invited all 150 patients scheduled for revision TKA (84) or THA (66) to participate in this prospective study, of whom 100% agreed. Data ultimately were missing for 31 patients, leaving 60 patients undergoing revision TKA and 59 undergoing revision THA (71% and 89% of the original group, respectively) for whom CRP level was measured in serum and synovial fluid samples. Patients were deemed to have a PJI (32) or no infection (87) using Musculoskeletal Infection Society criteria. Serum and synovial CRP levels were assayed using the same immunospectrophotometer and the correlation coefficient was calculated. Receiver operating characteristic curve analyses were performed to compare utility in diagnosing PJI, which included area under the curve, diagnostic threshold, and test sensitivity, specificity, predictive values, and accuracy. In 22 of 150 patients (14.7%), synovial CRP could not be measured because the sample was too viscous or hemolyzed. RESULTS: In the analyzed 119 samples, there was a strong correlation (r = 0.76; p < 0.001) between synovial and serum CRP. The area under the curve was 0.90 both for the synovial fluid (95% CI, 0.82-0.97) and serum (95% CI, 0.84-0.96) CRP assays. The diagnostic thresholds were 6.6 mg/L for synovial fluid and 11.2 mg/L for serum. Sensitivities, specificities, positive predictive value, negative predictive value, and accuracies were similar for synovial fluid and serum assays. CONCLUSIONS: Although recent studies have suggested a superiority of synovial fluid CRP over serum CRP for the diagnosis of PJI, we found that measurement of CRP in synovial fluid rather than serum using readily available assay equipment does not offer a diagnostic advantage in detection of PJIs. LEVEL OF EVIDENCE: Level II, diagnostic study. See the Instructions to Authors for a complete description of levels of evidence.

The 2013 Frank Stinchfield Award: Diagnosis of infection in the early postoperative period after total hip arthroplasty.

BACKGROUND: Diagnosis of periprosthetic joint infection (PJI) can be difficult in the early postoperative period after total hip arthroplasty (THA) because normal cues from the physical examination often are unreliable, and serological markers commonly used for diagnosis are elevated from the recent surgery. QUESTIONS/PURPOSES: The purposes of this study were to determine the optimal cutoff values for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), synovial fluid white blood cell (WBC) count, and differential for diagnosing PJI in the early postoperative period after primary THA. METHODS: We reviewed 6033 consecutive primary THAs and identified 73 patients (1.2%) who underwent reoperation for any reason within the first 6 weeks postoperatively. Thirty-six of these patients were infected according to modified Musculoskeletal Infection Society criteria. Mean values for the diagnostic tests were compared between groups and receiver operating characteristic curves generated along with an area under the curve (AUC) to determine test performance and optimal cutoff values to diagnose infection. RESULTS: The best test for the diagnosis of PJI was the synovial fluid WBC count (AUC = 98%; optimal cutoff value 12,800 cells/µL) followed by the CRP (AUC = 93%; optimal cutoff value 93 mg/L), and synovial fluid differential (AUC = 91%; optimal cutoff value 89% PMN). The mean ESR (infected = 69 mm/hr, not infected = 46 mm/hr), CRP (infected = 192 mg/L, not infected = 30 mg/L), synovial fluid WBC count (infected = 84,954 cells/µL, not infected = 2391 cells/µL), and differential (infected = 91% polymorphonuclear cells [PMN], not infected = 63% PMN) all were significantly higher in the infected group. CONCLUSIONS: Optimal cutoff values for the diagnosis of PJI in the acute postoperative period were higher than those traditionally used for the diagnosis of chronic PJI. The serum CRP is an excellent screening test, whereas the synovial fluid WBC count is more specific.

Outcomes of arthroscopic anterior shoulder instability in the beach chair versus lateral decubitus position: a systematic review and meta-regression analysis.

PURPOSE: This study aimed to systematically review the clinical outcomes and recurrence rates after arthroscopic anterior shoulder stabilization in the beach chair (BC) and lateral decubitus (LD) positions. METHODS: The authors performed a systematic review of multiple medical databases using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All English-language literature from 1990 to 2013 reporting clinical outcomes after arthroscopic anterior shoulder stabilization with suture anchors or tacks with a minimum 2-year follow-up period were reviewed by 2 independent reviewers. Data on recurrent instability rate, return to activity/sport, range of motion, and subjective outcome measures were collected. Study methodological quality was evaluated with the Modified Coleman Methodology Score (MCMS) and the Quality Appraisal Tool (QAT). To quantify the structured review of observational data, meta-analytic statistical methods were used. RESULTS: Sixty-four studies (38 BC position, 26 LD position) met inclusion criteria. A total of 3,668 shoulders were included, with 2,211 of patients in the BC position (average age, 26.7 ± 3.8 years; 84.5% male sex) and 1,457 patients in the LD position (average age, 26.0 ± 3.0 years; 82.7% male sex). The average follow-up was 49.8 ± 29.5 months in the BC group compared with 38.7 ± 23.3 months in the LD group. Average overall recurrent instability rates were 14.65 ± 8.4% in the BC group (range, 0% to 38%) compared with 8.5% ± 7.1% in the LD group (range, 0% to 30%; P = .002). The average postoperative loss in external rotation motion (in abduction) was reported in 19 studies in the BC group and in13 studies in the LD group, with an average loss of 2.4° ± 1.0° and 3.6° ± 2.6° in each group, respectively (P > .05). CONCLUSIONS: Excellent clinical outcomes with low recurrence rates can be obtained after arthroscopic anterior shoulder stabilization in either the BC or the LD position; however, lower recurrence rates are noted in the LD position. Additional long-term randomized clinical trials comparing these positions are needed to better understand the potential advantages and disadvantages of each position. LEVEL OF EVIDENCE: Level IV, systematic review of studies with Level I through Level IV evidence.