Not So Fast: Extended Oral Antibiotic Prophylaxis Does Not Reduce 90-Day Infection Rate Following Joint Arthroplasty.

INTRODUCTION: Periprosthetic joint infection (PJI) is a devastating complication following both total hip (THA) and knee (TKA) arthroplasty. Extended oral antibiotic prophylaxis (EOA) has been reported to reduce PJI following TJA in high-risk patients. The purpose of this study was to determine if EOA reduces PJI in all-comers and high-risk THA and TKA populations. METHODS: This is a retrospective cohort study, including 4,576 patients undergoing primary THA or TKA at a single institution from 2018 to 2022. Beginning in 2020, EOA prophylaxis was administered for 10 days following THA or TKA at our institution. Patients were separated into two cohorts (1,769 EOA, 2,807 no EOA) based on whether they received postoperative EOA. The 90-day and 1-year outcomes, with a focus on PJI, were then compared between groups. A subgroup analysis of high-risk patients was also performed. RESULTS: There was no difference in 90-day PJI rates between cohorts (EOA 1 versus no EOA 0.8%; P = 0.6). The difference in the rate of PJI remained insignificant at 1 year (EOA 1 versus no EOA 1%; P = 0.9). Similarly, our subgroup analysis of high-risk patients demonstrated no difference in postoperative PJI between EOA (n = 254) and no EOA (n = 396) (0.8 versus 2.3%, respectively; P = 0.2). Reassuringly, we also found no differences in the incidence of Clostridium difficile infection (CDI) (EOA 0.1 versus no EOA 0.1%; P > 0.9) or in antibiotic resistance among those who developed PJI within 90 days (EOA 59 versus no EOA 83%; P = 0.2). DISCUSSION: With the numbers available for analysis, extended oral antibiotic prophylaxis was not associated with PJI risk reduction following primary TJA when universally deployed. Furthermore, among high-risk patients, there was no statistically significant difference. While we did not identify increased antibiotic resistance or CDI, we cannot recommend wide-spread adoption of EOA prophylaxis, and clarification regarding the role of EOA, even in high-risk patients, is needed.

The prevalence of posterolateral tibial baseplate overhang: An anatomical CT study.

INTRODUCTION: Total Knee Arthroplasty (TKA) is used in patients with osteoarthritis who have failed conservative management to reduce pain, improve functional outcomes and ultimately quality of life. However, less than optimal patient satisfaction has led to continued improvements in design and technology of TKA. One factor that can limit patient satisfaction is postero-lateral overhang of the tibial baseplate. The purpose of our study is to utilize pre-operative CT scans to assess the prevalence of posterolateral tibial overhang with the use of a symmetric tibial baseplate component in a popular knee system with robotic assistance. METHODS: Ninety-eight (98) consecutive patients who underwent robotic-assisted total knee arthroplasty (TKA) were included in this study. Using both the most medial aspect of the tibial tubercle and the medial ⅓ of the tibial tubercle as reference points, we quantified the extent of posterolateral overhang when determining the rotation of the tibial component. RESULTS: Using the most medial aspect of the tibial tubercle as a reference point for rotation of the tibial baseplate, 63% of the instances of reviewed CT scans (369/588) had posterolateral overhang. Furthermore, 81% (406/588) had posterolateral overhang when using the medial ⅓ aspect of the tibial tubercle as the reference for rotation of the tibial baseplate. The average posterolateral tibial baseplate overhang was 1.5 mm (range 0-8 mm) when using the most medial aspect of the tibial tubercle and 2.4 mm (range 0-8 mm) when using the medial ⅓ tibial tubercle as the centering point for the tibial baseplate. DISCUSSION: Tibial baseplate overhang could lead to potential pain from irritation of soft tissues. To our knowledge, this is the first study that was able to valencquantify the amount of tibial baseplate overhang using pre-operative CT scans. Rotational alignment of the tibial baseplate needs to be balanced to ensure minimal lateral overhang while achieving sufficient external rotation of the tibial component. An asymmetric tibial component may provide a compromise in certain situations. LEVEL OF EVIDENCE: Diagnostic level IV case series.

Increased Oxidative Stress, Loop Gain And The Arousal Threshold Are Clinical Predictors Of Increased Apnea Severity Following Exposure To Intermittent Hypoxia.

PURPOSE: We determined if oxidative stress prior to sleep onset is correlated to loop gain (LG) and the arousal threshold (AT) during non-rapid eye movement (NREM) sleep. We also explored if LG and AT are correlated with apnea severity and indices of upper airway collapsibility during NREM sleep. METHODS: Thirteen male participants with obstructive sleep apnea (apnea-hypopnea index > 5 events/hr) were administered an antioxidant or placebo cocktail while exposed to mild intermittent hypoxia in the awake state. Thereafter, loop gain and measures of arousal, apnea severity and upper airway collapsibility were ascertained during NREM sleep. RESULTS: Modification in oxidative stress (i.e., 8-hydroxy-2-deoxyguanosine) prior to sleep onset was correlated to LG (r = 0.8, P = 0.003), the number (r = 0.71, P = 0.01) and duration (r = 0.63, P = 0.04) of apneic events and the percentage of time breathing was stable (r = -0.66, P = 0.03) during sleep. Using a forward stepwise regression analysis, our results showed that LG, AT, the ventilatory response to arousal and nadir end-tidal carbon dioxide were determinants of the apnea-hypopnea index (P value range = 0.04-0.001). In addition, the AT was a predictor of measures of upper airway collapsibility, including the hypopnea/apnea + hypopnea ratio and the degree of flow reduction that accompanied hypopneic events (P < 0.001). CONCLUSION: Modifications in oxidative stress following exposure to intermittent hypoxia during wakefulness are positively associated with loop gain and apnea severity during NREM sleep. Moreover, an increase in the arousal threshold is a predictor of increased upper airway collapsibility.

Clostridium difficile Colitis Following Revision Total Knee Arthroplasty: Incidence and Risk Factors.

BACKGROUND: Clostridium difficile-associated diarrhea (CDAD) is associated with adverse events and financial liability. As institutions continue to adopt CDAD rates as a quality control metric, it is important to identify patients at risk before surgery, including revision total knee arthroplasty (rTKA). This study was conducted to (1) determine the incidence of CDAD within 30 days of rTKA and (2) identify perioperative risk factors for CDAD following rTKA. METHODS: The American College of Surgeons National Surgical Quality Improvement Program was queried to identify 6023 rTKA procedures from 2015-2016. Preoperative and perioperative variables, including patient demographics, lab values, comorbidities, operative time, procedure type, presence of postoperative infections, and rates of CDAD were collected. Chi-square and Fisher's exact tests were used to detect differences between categorical variables, and t-tests were used to compare continuous variables. A stepwise logistic regression model was used to identify the risk factors for CDAD. RESULTS: The rate of CDAD within 30 days of rTKA was found to be 0.4% (24/6024). The CDAD rate following aseptic revision was 0.2% (12/4893), while the incidence of CDAD after septic revision was 1.1% (12/1130). Preoperative functional dependence (odds ratio [OR] = 5.14; P = .002), septic revision (OR = 2.77; P = .026), and cancer (OR = 14.26; P = .016) were statistically significant independent risk factors for CDAD after rTKA. CONCLUSION: The incidence of CDAD after rTKA is approximately 0.4% in the United States. Independent risk factors for CDAD include septic revision, preoperative functional dependence, and cancer. Prevention of CDAD in these higher risk patients must be considered before surgery and antibiotic selection for other infections should be managed judiciously.

Isolated Tibial Component Failure in Total Knee Arthroplasty: A Case Series Evaluating Inflammatory Response versus Mechanical Failure.

Total knee prostheses are routinely redesigned to improve performance, longevity, and to closer mimic the native kinematics of the knee. Despite continued improvements, all knee implants, even those with proven design features, have failures. We identified a cohort of patients with isolated tibial component failures that occurred in a popular and successful knee system. Our purpose was to (1) characterize the observed radiographic failure pattern; (2) investigate the biologic response that may have contributed to the failure; and (3) to determine if the failure mechanism was of a biological or a mechanical nature. Twenty-one knees from 19 patients met the inclusion criteria of isolated tibial component failure in a single knee implant system. Radiographs from the primary and revision knee surgery were analyzed for implant positioning and the failure pattern. Inflammatory biomarkers interleukin (IL)-1ß, IL-6, and tumor necrosis factor (TNF)-α were available in 16/21 knees and peripheral CD14+/16+ monocytes were measured in 14 of the aforementioned 16 knee revisions. Serum CD3, CD4, and CD19 were measured in 10 of the aforementioned 14 knees. Additionally, white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were measured to rule out infection as a cause of the cytokine upregulation. Radiographic findings demonstrated that all of the 21 tibial components were implanted in either neutral or 2 to 3 degrees varus in the coronal plane, and none of the revisions was implanted in valgus. All tibias showed obvious radiographic loosening and the implant failed into varus. The inflammatory biomarkers IL-1ß, IL-6, and TNF-α were negative. WBC, ESR, and CRP were normal. Serum CD3, CD4, and CD19 flow cytometry analyses were found to be in the normal range. Peripheral CD14+/16+ and total CD16+ monocytes measurements were consistent with previous findings of patients with osteoarthritis, rather than particulate-induced inflammatory loosening. The findings support the implant failure observed in our study occurred by a different mechanism than the wear debris-induced aseptic loosening. We believe that a mechanical failure can occur based on our findings. The loosening, collapse, and debonding from the cement may have been related to the implantation technique, stresses due to favorable rotational freedoms of the implant, or patient characteristics/behavior. Continued exploration into implant failure mechanisms and particularly into the biologic response associated with failure is ongoing.

Preoperative and Postoperative Opiate Use by the Arthroplasty Patient.

BACKGROUND: As opioid use increases nationally, the arthroplasty surgeon is likely to see more patients taking opioid analgesics on initial presentation. The purpose of this study was to investigate the use of opiate medication in the preoperative and postoperative patient undergoing primary total joint arthroplasty. METHODS: From October 2010 to November 2011, data on 367 consecutive patients who underwent primary total joint arthroplasty were reviewed. Using the Michigan Automated Prescription System database, data were collected on opiate use from 3 months preop to 12 months postop. Patients were grouped by preoperative opiate use. Patients with ≥2 opiate prescriptions filled per 6-week period before surgery were considered chronic opiate users. RESULTS: Three hundred fifteen patients fit our inclusion/exclusion criteria. There were 158 primary total knee and 157 primary total hip arthroplasty patients. At 1 year after operation, 64% of chronic opiate users were still being prescribed opiates compared with 22% of the control group (P < .001). Thirty-one percent of the chronic opiate users were discharged to an extended care facility compared to 21% of the control group (P = .123). Of all the opiate prescriptions, 77% were written by a practitioner other than the surgeon. CONCLUSIONS: Opiates are frequently prescribed by providers other than the surgeon preoperatively and postoperatively. The use of opiates that were presumably prescribed to treat joint pain was continued for more than 1 year postoperatively in 64% of cases. Patients taking multiple opiates or more potent opiates preoperatively filled more prescriptions postoperatively. Chronic use of opiates negatively influenced the discharge disposition.

Impact of repeated daily exposure to intermittent hypoxia and mild sustained hypercapnia on apnea severity.

We examined whether exposure to intermittent hypoxia (IH) during wakefulness impacted on the apnea/hypopnea index (AHI) during sleep in individuals with sleep apnea. Participants were exposed to twelve 4-min episodes of hypoxia in the presence of sustained mild hypercapnia each day for 10 days. A control group was exposed to sustained mild hypercapnia for a similar duration. The intermittent hypoxia protocol was completed in the evening on day 1 and 10 and was followed by a sleep study. During all sleep studies, the change in esophageal pressure (ΔPes) from the beginning to the end of an apnea and the tidal volume immediately following apneic events were used to measure respiratory drive. Following exposure to IH on day 1 and 10, the AHI increased above baseline measures (day 1: 1.95 ± 0.42 fraction of baseline, P ≤ 0.01, vs. day 10: 1.53 ± 0.24 fraction of baseline, P < 0.06). The indexes were correlated to the hypoxic ventilatory response (HVR) measured during the IH protocol but were not correlated to the magnitude of ventilatory long-term facilitation (vLTF). Likewise, ΔPes and tidal volume measures were greater on day 1 and 10 compared with baseline (ΔPes: -8.37 ± 0.84 vs. -5.90 ± 1.30 cmH(2)0, P ≤ 0.04; tidal volume: 1,193.36 ± 101.85 vs. 1,015.14 ± 119.83 ml, P ≤ 0.01). This was not the case in the control group. Interestingly, the AHI on day 10 (0.78 ± 0.13 fraction of baseline, P ≤ 0.01) was significantly less than measures obtained during baseline and day 1 in the mild hypercapnia control group. We conclude that enhancement of the HVR initiated by exposure to IH may lead to increases in the AHI during sleep and that initiation of vLTF did not appear to impact on breathing stability. Lastly, our results suggest that repeated daily exposure to mild sustained hypercapnia may lead to a decrease in breathing events.

The hypoxic ventilatory response and ventilatory long-term facilitation are altered by time of day and repeated daily exposure to intermittent hypoxia.

This study examined whether time of day and repeated exposure to intermittent hypoxia have an impact on the hypoxic ventilatory response (HVR) and ventilatory long-term facilitation (vLTF). Thirteen participants with sleep apnea were exposed to twelve 4-min episodes of isocapnic hypoxia followed by a 30-min recovery period each day for 10 days. On days 1 (initial day) and 10 (final day) participants completed the protocol in the evening (PM); on the remaining days the protocol was completed in the morning (AM). The HVR was increased in the morning compared with evening on the initial (AM 0.83 ± 0.08 vs. PM 0.64 ± 0.11 l·min⁻¹·%SaO2⁻¹; P ≤ 0.01) and final days (AM 1.0 ± 0.08 vs. PM 0.81 ± 0.09 l·min⁻¹·%SaO2⁻¹; P ≤ 0.01, where %SaO2 refers to percent arterial oxygen saturation). Moreover, the magnitude of the HVR was enhanced following daily exposure to intermittent hypoxia in the morning (initial day 0.83 ± 0.08 vs. final day 1.0 ± 0.08 l·min⁻¹·%SaO2⁻¹; P ≤ 0.03) and evening (initial day 0.64 ± 0.11 vs. final day 0.81 ± 0.09 l·min⁻¹·%SaO2⁻¹; P ≤ 0.03). vLTF was reduced in the morning compared with the evening on the initial (AM 19.03 ± 0.35 vs. PM 22.30 ± 0.49 l/min; P ≤ 0.001) and final (AM 20.54 ± 0.32 vs. PM 23.11 ± 0.54 l/min; P ≤ 0.01) days. Following daily exposure to intermittent hypoxia, vLTF was enhanced in the morning (initial day 19.03 ± 0.35 vs. final day 20.54 ± 0.32 l/min; P ≤ 0.01). We conclude that the HVR is increased while vLTF is decreased in the morning compared with the evening in individuals with sleep apnea and that the magnitudes of these phenomena are enhanced following daily exposure to intermittent hypoxia.