Clendenen, Steven R.

Abstract Introduction: Total knee arthroplasty (TKA) for knee osteoarthritis (OA) provides pain relief and functional improvement for many patients. The endocannabinoid system (ECS) regulates pain and inflammation through central and peripheral mechanisms and may be affected by acetaminophen. There is limited information on how surgery and perioperative care affect the ECS. Objective: We designed this study to examine the effect of surgery and acetaminophen on the ECS and determine whether perioperative endocannabinoids were associated with pain resolution after surgery. Methods: Forty adult patients with OA undergoing TKA were enrolled in a prospective observational cohort study and provided preoperative cerebrospinal fluid (CSF) and blood samples at 3 time points (before surgery, after intravenous acetaminophen, and 24 hours postoperative). Defense and Veterans Pain Rating Scale scores at rest and with activity were recorded in the preoperative holding area, in the operating room after intravenous acetaminophen before spinal anesthesia, and 24 to 48 hours postoperatively. Cerebrospinal fluid and plasma endocannabinoids were quantified using a validated liquid chromatography/mass spectrometry assay. We analyzed the data using linear regression models with sex, age, and body mass index as covariates. Results: Patients undergoing TKA have higher CSF and plasma concentrations of N-acylethanolamines anandamide and its congeners compared with control subjects. Patients with higher pain scores had lower CSF anandamide levels before and after surgery and higher levels of 2-arachidonoylglycerol before surgery but not after. Conclusion: Chronic pain, acetaminophen, and surgery are associated with endogenous endocannabinoid levels and may present an opportunity for developing targeted nonopioid perioperative analgesia after TKA.

Objective: To evaluate the efficacy of regional anesthesia (RA) in enabling arteriovenous fistula (AVF) creation in patients with small-caliber veins who would typically receive arteriovenous grafts (AVG), and to compare access outcomes between AVF and AVG cohorts. Methods: We conducted a retrospective analysis of a prospectively maintained database from 2018 through 2024 involving patients with chronic kidney disease (CKD) requiring access creation. Eligible patients were those aged 18 years or older with inadequate veins for AVF creation based on initial ultrasound vein mapping. All patients underwent RA prior to the access creation and had a repeated intraoperative vein mapping at least 30 min after RA. Patients whose veins were sufficiently dilated and met the criteria for AVF creation underwent AVF formation; otherwise, an AVG was created. Outcomes included access maturation, patency rates, access failure, abandonment, and mortality. Statistical analysis was performed using R software, with significance set at p < 0.05. Results: Of the 106 patients, 67 (63.2%) underwent AVF creation post-RA due to sufficient vein dilation, while 39 (36.8%) received AVGs. Baseline vein diameters and comorbidities were comparable between groups. AVF maturation was achieved in 83.6% of AVF patients, with longer times to successful cannulation compared to AVG (median 187.0 vs 80.0 days, p = 0.037). Kaplan-Meier analysis revealed no difference in primary patency ( p = 0.97), but AVF patients had superior primary assisted ( p = 0.015) and secondary patency ( p = 0.033), and lower access failure rates ( p = 0.034) compared to AVG patients. Access abandonment and mortality rates did not differ significantly between groups. Conclusions: RA-induced venodilation enables the use of veins previously deemed inadequate for AVF creation, leading to improved access outcomes compared to AVG placement. Implementing RA may increase AVF utilization and enhance patient outcomes in hemodialysis access surgery.

Abstract Postoperative pain control after total knee arthroplasty (TKA) remains challenging, particularly in patients utilizing chronic opioids preoperatively. Our study aimed to evaluate the effect of regional nerve blockade on perioperative pain control outcomes after TKA in patients using or not using chronic preoperative opioids. A retrospective review of our institutional database identified 434 chronic opioid patients defined as documented ongoing use greater than 3 months prior to contemporary TKA. Patients were 1:1 matched to nonopioid users based upon age, sex, body mass index, and regional block type (single-shot adductor canal block [ACB, 29%], 3-day ACB catheter [31%], or no block [41%]). All patients underwent primary TKA using periarticular injections and contemporary multimodal pain management. Immediate and 90-day postoperative outcomes, including Knee Osteoarthritis Outcome Score, Junior (KOOS, Jr), were compared via univariate analysis among the matched cohort and regional block type among chronic opioid patients. Chronic opioid patients demonstrated higher inpatient opioid use than controls (90 vs. 65 oral morphine equivalents [OMEs], respectively, p < 0.01), but no significant differences existed in length of stay (LOS), discharge pain scores, 90-day readmission or KOOS, Jr (all p ≥ 0.05). When comparing chronic opioid patients according to block type, those receiving no block had the highest LOS (1.6 days, p < 0.01), discharge pain score (5.0, p < 0.01), and inpatient opioid use (80 OMEs, p < 0.01) compared with either ACB. The subgroup receiving an ACB catheter demonstrated a significantly higher 90-day readmission rate (9%, p < 0.05). Patients utilizing chronic opioids preoperatively require more opioids in the immediate postoperative period after TKA compared with nonopioid users despite contemporary modalities. Nonetheless, the use of any type of ACB provides improved pain control in these patients.

The infrapatellar branch of the saphenous nerve (IPBSN) is implicated in nerve injury from different knee surgeries because of its intimate course relative to the knee joint capsule. Pain physicians encounter patients in their practice for the management of neuralgia of this nerve or in the context of advanced management of knee osteoarthritis. This article aims to provide a comprehensive review of the anatomy, sonoanatomy, and the intervention of the IPBSN in pain management of infrapatellar neuralgia and chronic knee pain.

AbstractIntroductionPersistent pain following breast surgery is common and may be challenging to treat. In patients refractory to conservative treatments, ultrasound‐guided fascial plane blocks of thoracic nerves can be a useful option.ResultsThis type of neuro blockade technique provides advantages in terms of safety and efficacy that are convenient for physicians managing refractory and complex cases of post‐breast surgery syndrome.ConclusionThis technical review aims to present an up‐to‐date summary of the most common ultrasound‐guided fascial plane blocks for chronic pain in post‐breast surgery patients, provide a detailed technical description of each intervention, and propose preferred injections based on the anatomical location of the pain.

Background Transvenous embolization is emerging as a promising treatment for cerebrospinal fluid-venous fistulas (CVF) associated with spontaneous intracranial hypotension (SIH). Objective To perform an independent validation of the efficacy and safety of the procedure and describe the procedural techniques used at our institution. Methods A retrospective review was performed including consecutive patients with SIH who had undergone CVF embolization with 3-month clinical and imaging follow-up. Clinical evaluation included the Patient Global Impression of Change (PGIC) Scale and six-item Headache Impact Test (HIT-6). Bern SIH score was used for imaging evaluation on brain MRI. Post-treatment changes in scores were assessed by Wilcoxon signed rank test. Procedural technical details, including use of upper-extremity access and dual-microcatheter pressure cooker technique, were recorded. Results 18 patients (13 female, median age 60 years) were included. 17 (94%) procedures were performed with upper-extremity access and 12 (67%) using dual-microcatheter pressure cooker technique. After embolization, 16 (89%) patients reported much or very much improved at follow-up PGIC; median (IQR) HIT-6 score improved from 68 (62–72) to 36 (36–38) and Bern SIH score improved from 8 (6–8) to 3 (1.5–3.5), p values <0.001. Side effects were transient embolization site back pain in 15 (83%) and rebound intracranial hypertension requiring medical management in 9 (50%) patients. HIT-6 and Bern SIH score changes were similar between conventional and pressure cooker techniques ( p values >0.05). Conclusion Transvenous embolization is independently validated as a highly effective and safe treatment for CVF and is feasible using upper-extremity venous access. Dual-microcatheter and balloon/coil pressure cooker techniques may be used to optimize distribution of embolic material and potentially, treatment efficacy.

Introduction Total knee arthroplasty is a common operation performed to relieve pain and restore functional activity. While overall widely successful, a subset of patients has continued pain postoperatively with no identifiable cause. Neuroma formation has been identified as a possible contributor to this unexplained pain, often necessitating an additional procedure for neuroma removal. The purpose of our study was to evaluate if prophylactic neurectomy could reduce the occurrence of postoperative pain. Methods A total of 112 patients were compared, 44 control patients and 68 neurectomy patients. Demographic information, Numerical rating pain scale (NRS) and Knee Society Scores (KSS) were collected pre- and post-operatively. Patients were additional asked if they were overall satisfied with the operation. Results There were no differences between groups with respect to age (Median: 71 vs 69 years, p = 0.28), male sex (41% vs 44%, p = 0.85), or body mass index (Median: 32.2 vs 31.3, p = 0.80). When comparing the degree of change following surgery there were no statistically significant differences observed in NRS pain scores (Median change: −7 vs −6, p = 0.89) or KSS scores (Median change: +44 vs +40, p = 0.14). Similarly, there was no statistically significant difference in overall patient-reported satisfaction with the knee replacement (82.5% vs 86.6%, p = 0.59). Conclusion We did not find a statistically significant difference in NRS, KSS, or overall patient satisfaction between the prophylactic neurectomy and control patient groups. Larger studies with evaluation of the nerve diameter will be needed to determine which patients are at risk for symptomatic neuroma development following total knee arthroplasty.