Postoperative Glycemic Variability and Adverse Outcomes After Posterior Cervical Fusion.

INTRODUCTION: Posterior cervical decompression and fusion (PCDF) is a procedure commonly performed to help alleviate symptoms and improve quality of life in patients experiencing cervical spondylotic myelopathy, multilevel stenosis, and cervical deformity. Although various risk factors have been linked to adverse outcomes in patients after PCDF, this is the first study that specifically explores postoperative glycemic variability and its association with adverse outcomes. METHODS: A retrospective cohort study was conducted with a total of 264 patients after PCDF procedures that had available postoperative blood glucose measurements. Patients were divided into tertiles based on their coefficient of variation as an indicator of glycemic variability. Outcomes measured included inpatient complications, length of stay (LOS), 90-day readmission, revision, and surgical site infection rates. RESULTS: Results showed a significant difference in glycemic variability among tertiles with respect to LOS (P = 0.01). The average LOS for the first, second, and third tertiles was 3.90 (3.20, 4.59), 5.73 (4.45, 7.00), and 6.06 (4.89, 7.22), respectively. Logistic regression analysis showed significantly higher odds of readmission (odds ratio: 4.77; P = 0.03) and surgical site infections (odds ratio: 4.35; P = 0.04) in the high glycemic variability group compared with the low glycemic variability group within 90 days of surgery. No significant difference was noted among tertiles with respect to inpatient complications. DISCUSSION: This study establishes a relationship between postoperative glycemic variability and LOS, as well as 90-day readmission and surgical site infection rates after PCDF. Our results suggest that limiting fluctuations in blood glucose levels may curtail inpatient healthcare costs related to in-hospital stay. Although immediate postoperative glycemic variability is ultimately acceptable, before discharge, proper glucose management plans should be in place to help prevent adverse patient outcomes.

Utilizing the Time Trade-Off, Standard Gamble, and Willingness to Pay Utility Measures to Evaluate Health-Related Quality of Life Prior to Knee or Hip Arthroplasty.

BACKGROUND: Time trade-off, standard gamble, and willingness to pay assess the number of years, risk of death, and income a patient would give up for perfect health. These questions were used to evaluate the impact knee arthritis, hip arthritis, or failed total knee (TKA) or hip arthroplasty (THA) has on patients' health-related quality of life prior to surgery. METHODS: Three hundred sixty patients including 176 undergoing primary TKA, 127 undergoing primary THA, 31 undergoing revision TKA, and 26 undergoing revision THA were assessed. Time trade-off and standard gamble were converted to utility scores with 1.0 suggesting perfect health and 0 suggesting preference for death rather than living in current state. Willingness to pay is the percentage of yearly income that a patient would pay for perfect health. RESULTS: The mean time trade-off, standard gamble, and willingness to pay scores were 0.74, 0.83, and 0.32 without significant difference between procedures with the numbers available for study (P = .16, .31, and 0.41, respectively). Increasing body mass index was correlated with decreasing time trade-off scores (P = .014). CONCLUSION: Patients scheduled for primary or revision THA and TKA would accept an average 17% risk of death, lose 2.6 years of an additional 10-year life expectancy, and pay 32% of their income for perfect health. The time trade-off (0.74) was similar to patients with history of acute myocardial infarction (0.74) or minor stroke (0.72) and worse than those with chronic hepatitis C (0.83) or human immunodeficiency virus/acquired immunodeficiency syndrome infection (0.86). These data highlight the high value that patients place on adult reconstructive procedures.

Nephrotoxicity After the Treatment of Periprosthetic Joint Infection With Antibiotic-Loaded Cement Spacers.

BACKGROUND: Treatment of periprosthetic joint infections commonly involves insertion of an antibiotic-loaded cement spacer (ACS). The risk for acute kidney injury (AKI) related to use of antibiotic spacers has not been well defined. We aimed to identify the incidence of and risk factors for AKI after placement of an ACS. METHODS: We performed a prospective cohort study of patients with an infected primary total hip or knee arthroplasty treated with ACSs with vancomycin, gentamicin, and tobramycin. Serum creatinine and glomerular filtration rate data were collected at baseline and weekly intervals for 8 weeks. Patients were classified into Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) stages to determine incidence of AKI. Risk factors for kidney injury were identified via regression analysis. RESULTS: A total of 37 patients (20 total knee arthroplasty and 17 total hip arthroplasty) were included. During the 8 weeks after ACS placement, 10 patients (27%) fit RIFLE criteria for kidney injury and 2 patients (5%) fit RIFLE criteria for kidney failure. No baseline patient characteristics were associated with development of AKI. CONCLUSION: Patients should be monitored closely for development of AKI after placement of ACSs for the treatment of periprosthetic joint infection. Further research into minimizing risk for AKI is warranted.

The Alpha-Defensin Test for Diagnosing Periprosthetic Joint Infection in the Setting of an Adverse Local Tissue Reaction Secondary to a Failed Metal-on-Metal Bearing or Corrosion at the Head-Neck Junction.

BACKGROUND: In patients with adverse local tissue reaction (ALTR) secondary to a failed metal-on-metal (MoM) bearing or corrosion at the head-neck junction in a metal-on-polyethylene bearing, ruling in or out periprosthetic joint infection (PJI) can be challenging. Alpha-defensin has emerged as an accurate test for PJI. The purpose of this multicenter, retrospective study was to evaluate the accuracy of the alpha-defensin synovial fluid test in detecting PJI in patients with ALTR. METHODS: We reviewed medical records of 26 patients from 3 centers with ALTR that had an alpha-defensin test performed. Patients were assessed for PJI using the Musculoskeletal Infection Society criteria. Thirteen of these subjects had MoM total hip arthroplasty, 9 had ALTR secondary to head-neck corrosion, and 4 had MoM hip resurfacing. RESULTS: Only 1 of the 26 patients met Musculoskeletal Infection Society criteria for infection. However, 9 hips were alpha-defensin positive, including 1 true positive and 8 that were falsely positive (31%). All 8 of the false positives were also Synovasure positive, although 5 of 8 had an accompanying warning stating the results may be falsely positive due to a low synovial C-reactive protein value. CONCLUSION: Similar to synovial fluid white blood cell count, alpha-defensin testing is prone to false-positive results in the setting of ALTR. Therefore, we recommend an aggressive approach to ruling out PJI including routine aspiration of all hips with ALTR before revision surgery to integrate the synovial fluid blood cell count, differential, cultures and adjunctive tests like alpha-defensin to allow for accurate diagnosis preoperatively.

Systemic Absorption of Antibiotics From Antibiotic-Loaded Cement Spacers for the Treatment of Periprosthetic Joint Infection.

BACKGROUND: Two-stage treatment of periprosthetic joint infections involves placement of high-dose antibiotic-loaded cement spacers (ACSs). Reports of ACS-induced nephrotoxicity have raised concern regarding systemic absorption of antibiotics after ACS placement. We sought to characterize the serum concentrations of antibiotics that occur after ACS placement. METHODS: We performed a prospective study of patients with an infected primary total hip (THA) or knee arthroplasty (TKA) treated with standardized ACSs with vancomycin, gentamicin, and tobramycin. Serum antibiotic levels were collected weekly for 8 weeks. RESULTS: Twenty-one patients (10 THA, 11 TKA) were included. Mean serum gentamicin levels ranged between 0.275±0.046 and 0.364±0.163 mg/L; mean serum tobramycin levels ranged from 0.313±0.207 to 0.527±0.424 mg/L; and mean serum vancomycin levels ranged from 5.46±6.6 to 15.34±9.6 mg/L. Serum antibiotic levels were detectable throughout the 8-week duration of ACS treatment. Regression analysis found that diabetes (coefficient 6.73, 95% CI 0.92-12.54, P < .05), blood urea nitrogen (coefficient 0.83, 95% CI 0.45-1.22, P < .001), number of cement doses (coefficient 3.71, 95% CI 0.76-6.66, P < .05), and use of systemic vancomycin (coefficient 6.24, 95% CI 2.72-9.75, P < .001) correlated with serum vancomycin levels. Patient age (coefficient -0.01, 95% CI -0.02 to 0, P < .01) and male sex (coefficient 0.20, 95% CI 0-0.41, P < .05) correlated with serum aminoglycoside level. CONCLUSION: Systemic absorption of antibiotics from high-dose ACS persists for at least 8 weeks. Patients should be monitored closely for complications related to systemic absorption of antibiotics from ACS treatment.

Poor Outcomes of Irrigation and Debridement in Acute Periprosthetic Joint Infection With Antibiotic-Impregnated Calcium Sulfate Beads.

BACKGROUND: One proposed strategy to increase the success of irrigation and debridement with implant retention for the treatment of acute periprosthetic joint infection (PJI) is the use of dissolvable antibiotic-impregnated calcium sulfate beads to provide a local depot of antibiotics. The purpose of this study was to evaluate the outcome of such an approach. METHODS: Thirty-two patients with acute hematogenous (18 patients; 1 bilateral) or acute postoperative (14 patients) PJIs who underwent irrigation and debridement with implant retention and addition of antibiotic-impregnated calcium sulfate beads were retrospectively reviewed. PJI followed 27 total knee arthroplasties and 6 total hip arthroplasties. The most common infecting organisms were methicillin-sensitive Staphylococcus aureus (13 of 33) and Streptococcus (9 of 33). The primary outcome parameter was recurrence of infection according to the Musculoskeletal Infection Society criteria. Patients were followed up for a minimum of 3 months or until failure. RESULTS: At a mean of 12.7 months (range, 3-30 months), 16 of the 33 patients failed (48%). Acute hematogenous and acute postoperative PJI had similar failure rates at 47% and 50%, respectively (P = .88). Seven failures required a 2-stage exchange, while 8 patients were treated with chronic antibiotic suppression, being unwilling or unable to undergo further surgical intervention. CONCLUSION: The addition of antibiotic-impregnated calcium sulfate beads does not appear to improve outcomes of irrigation and debridement with implant retention in the setting of acute hematogenous or acute postoperative PJI. Given the short follow-up in this report, this represents a best-case scenario and the overall failure rate may be higher with further follow-up.

Incidence, Risk Factors, and Clinical Implications of Pneumonia Following Total Hip and Knee Arthroplasty.

BACKGROUND: The purpose of this study is to determine the incidence, risk factors, and clinical implications of pneumonia following total joint arthroplasty (TJA). METHODS: The American College of Surgeons National Surgical Quality Improvement Program was used to conduct a retrospective cohort study of patients undergoing TJA. Independent risk factors for the development of pneumonia within 30 days of TJA were identified using multivariate regression. Mortality and readmission rates were compared between patients who did and did not develop pneumonia. Multivariate regression was used to adjust for all demographic, comorbidity, and procedural characteristics. RESULTS: In total, 171,200 patients met inclusion criteria, of whom 66,493 (38.8%) underwent THA and 104,707 (61.2%) underwent TKA. Of the 171,200 patients, 590 developed pneumonia, yielding a rate of 0.34% (95% confidence interval = 0.32%-0.37%). Independent risk factors for pneumonia were chronic obstructive pulmonary disease, diabetes mellitus, greater age (most notably ≥80 years), dyspnea on exertion, dependent functional status, lower body mass index, hypertension, current smoker status, and male sex. The subset of patients who developed pneumonia following discharge had a higher readmission rate (82.1% vs 3.4%, adjusted relative risk [RR] = 16.6, P < .001) and a higher mortality rate (3.7% vs 0.1%, adjusted RR = 19.4, P < .001). Among 124 total mortalities, 22 (17.7%) occurred in patients who had developed pneumonia. CONCLUSION: Pneumonia is a serious complication following TJA that occurs in approximately 1 in 300 patients. Approximately 4 in 5 patients who develop pneumonia are subsequently readmitted, and approximately 1 in 25 die. Given the serious implications of this complication, evidence-based pneumonia prevention programs including oral hygiene with chlorhexidine, sitting upright for meals, elevation of the head of the bed to at least 30°, aggressive incentive spirometry, and early ambulation should be considered for patients at greatest risk.