Infiltration of local anesthetic in the Interspace between the popliteal artery and capsule of the posterior knee "IPACK block" versus adductor canal block "ACB" for pain relief after open wedge high tibial osteotomy: a randomized clinical trial.

BACKGROUND: A high tibial osteotomy is usually associated with severe postoperative pain. Both adductor canal block (ACB) and interspace between the popliteal artery and capsule of the posterior knee (IPACK) have been described as effective block techniques for providing analgesia after knee surgeries, with few comparisons in wedge osteotomy cases. We aim to compare the postoperative analgesic profile of the previously mentioned two block techniques in patients undergoing tibial osteotomies. METHODS: Sixty patients were enrolled in this randomized prospective trial (30 received IPACK and 30 received ACB). Both blocks were installed before the spinal anesthesia after infiltration of 2 mL lidocaine 2%. Twenty mL of bupivacaine 0.25% mixed with dexamethasone as anesthetic adjuvant were used for both blocks. The postoperative analgesic profiles were compared between the two groups. RESULTS: Postoperative pain scores were lower in the IPACK group, and that decrease was evident throughout the first 10 hours postoperatively. Additionally, the duration of analgesia was much prolonged with the same block (487.50±82.39 vs. 301.93±92.06 minutes with ACB). There was a significant decline in postoperative analgesic consumption (1.27±0.45 vs. 1.8±0.61 gm, P=0.000), and a significant increase in the ambulation distance (19.10±0.60 vs. 17.73±0.45 m, P=0.000) with a significant decline in the duration of hospitalization (43.27±7.61 vs. 54±8.35 hours) in the IPACK group compared to the ACB group. CONCLUSIONS: IPACK is a superior block technique compared to ACB in patients undergoing high tibial osteotomy regarding postoperative analgesia, ambulation distance, and patient satisfaction with little rate of adverse events in both groups.

Efficacy of adding infiltration between the popliteal artery and the capsule of the posterior knee (IPACK) to adductor canal block and local infiltration analgesia in total knee arthroplasty: A retrospective cohort study.

OBJECTIVE: Local infiltration analgesia (LIA), adductor canal block (ACB), and infiltration between the popliteal artery and the capsule of the posterior knee (IPACK) are popular multimodal analgesia techniques used during total knee arthroplasty (TKA). This study aimed to explore the efficacy of adding the IPACK technique to ACB and LIA in patients undergoing TKA. METHODS: In this retrospective cohort study, patients who underwent primary unilateral TKA were divided into two groups based on their date of admission. Sixty-three patients underwent IPACK, ACB and LIA (IPACK group) during surgery, while 60 patients underwent ACB and LIA (control group). The primary outcome was the postoperative administration of morphine hydrochloride as a rescue analgesic. Secondary outcomes included time to first rescue analgesia, postoperative pain assessed using the visual analog scale (VAS), functional recovery assessed by knee range of motion and ambulation distance, time until hospital discharge, and complication rates. RESULTS: The two groups were similar in average postoperative 0-to-24-h morphine consumption (11.8 mg for the control group vs 12.7 mg for the IPACK group, p = .428) and average total morphine consumption (18.2 mg vs 18.0 mg, p = .983) during hospitalization. There were also no significant differences in the secondary outcomes. CONCLUSIONS: The addition of IPACK to ACB and LIA did not provide any clinical analgesic benefits. Orthopedic surgeons and anesthesiologists are justified in using ACB and LIA without IPACK for TKA.

Staged bilateral release of the popliteus muscle using a posterior surgical approach to the popliteal fossa to treat type 4 popliteal artery entrapment.

Popliteal artery entrapment syndrome (PAES) is a rare cause of intermittent claudication in the young. Aberrant embryological development results in entrapment of the popliteal artery by myofascial structures of the popliteal fossa. Type 4 PAES is due to aberrant development of the popliteus muscle superficial to the popliteal artery. We present a case of bilateral type 4 PAES, along with intraoperative photography highlighting the anatomical cause for this pathology. Both limbs in this patient were treated successfully with surgical release of the entrapping popliteus muscle via a posterior surgical approach to the popliteal fossa. This report emphasises the importance of determining popliteal artery integrity and entrapment subtype to guide the management of this condition.

Perfusion increase in foot angiosomes: Comparison between direct and indirect revascularization of crural arteries.

BACKGROUND AND AIMS: In retrospective studies, wound healing and leg salvage have been better if revascularization is targeted to the crural artery supplying arterial flow to the wound angiosome. No data exist on how revascularization changes the blood flow in foot angiosomes. The aim of this study was to evaluate the change in perfusion after infrapopliteal artery revascularization in all foot angiosomes and to compare directly revascularized (DR) angiosomes to the indirectly revascularized (IR) angiosomes. METHODS: In this prospective study, foot perfusion was measured with indocyanine green fluorescence imaging (ICG-FI) before and after either surgical or endovascular below-knee revascularization. According to angiograms, we divided the foot angiosomes into DR and IR angiosomes. Furthermore, in a subanalysis, the IR angiosomes were graded as IR_Coll+ angiosomes if there were strong collaterals arising from the artery which was revascularized, and as IR_Coll- angiosomes if strong collaterals were not seen. RESULTS: A total of 72 feet (28 bypass, 44 endovascular revascularizations) and 282 angiosomes were analyzed. Surgical and endovascular revascularization increased perfusion significantly in both DR and IR angiosomes. After bypass surgery, the increase in DR angiosomes was 55 U and 53 U in IR angiosomes; there were no significant difference in the perfusion increase between IR and DR angiosomes. After endovascular revascularization, perfusion increased significantly more, 40 U, in DR angiosomes compared to 26 U in IR angiosomes (p < 0.05). In the subanalysis of IR angiosomes, perfusion increased significantly after surgical bypass regardless of whether strong collaterals were present or not. After endovascular revascularization, however, a significant perfusion increase was noted in the IR_Coll+ but not in the IR_Coll- subgroup. CONCLUSION: Open revascularization increased perfusion equally in DR and IR angiosomes, whereas endovascular revascularization increased perfusion significantly more in DR than in IR angiosomes. Strong collateral network may help increase perfusion in IR angiosomes.

Nadir blood pressure responses to longer consecutive cardiac cycle sequences absent of sympathetic bursts are associated with popliteal endothelial-dependent dilation.

PURPOSE: The nadir pressure responses to cardiac cycles absent of muscle sympathetic nerve activity (MSNA) bursts (or non-bursts) are typically reported in studies quantifying sympathetic transduction, but the information gained by studying non-bursts is unclear. We tested the hypothesis that longer sequences of non-bursts (≥8 cardiac cycles) would be associated with a greater nadir diastolic blood pressure (DBP) and that better popliteal artery function would be associated with an augmented reduction in DBP. METHODS: Resting beat-by-beat DBP (via finger photoplethysmography) and common peroneal nerve MSNA (via microneurography) were recorded in 39 healthy, adults (age 23.4 ± 5.3 years; 19 females). For each cardiac cycle absent of MSNA bursts, the mean nadir DBP (ΔDBP) during the 12 cardiac cycles following were determined, and separate analyses were conducted for ≥8 or < 8 cardiac cycle sequences. Popliteal artery endothelial-dependent (via flow-mediated dilation; FMD) and endothelial-independent vasodilation (via nitroglycerin-mediated dilation; NMD) were determined. RESULTS: The nadir DBP responses to sequences ≥8 cardiac cycles were larger (-1.40 ± 1.27 mmHg) than sequences <8 (-0.38 ± 0.46 mmHg; p < 0.001). In adjusting for sex and burst frequency (14 ± 8 bursts/min), larger absolute or relative FMD (p < 0.01), but not NMD (p > 0.53) was associated with an augmented nadir DBP. This overall DBP-FMD relationship was similar in sequences ≥8 (p = 0.04-0.05), but not <8 (p > 0.72). CONCLUSION: The DBP responses to non-bursts, particularly longer sequences, were inversely associated with popliteal endothelial function, but not vascular smooth muscle sensitivity. This study provides insight into the information gained by quantifying the DBP responses to cardiac cycles absent of MSNA.

A Novel Sirolimus-Coated Balloon for the Treatment of Femoropopliteal Lesions: The SELUTION SFA Japan Trial.

BACKGROUND: Sirolimus-coated balloons (SCB) for the treatment of femoropopliteal (FP) lesions have not been systematically studied, but initial outcomes from early studies are promising. OBJECTIVES: The authors sought to evaluate the safety and efficacy of the SELUTION SLR SCB, composed of proprietary microreservoir technology combining sirolimus and biodegradable polymer, when used to treat mild-to-moderate FP disease in a Japanese population. METHODS: This multicenter, prospective, single-arm study (SELUTION SFA JAPAN) enrolled 134 patients with FP disease. It was independently adjudicated by an imaging core laboratory and clinical events committee. The primary endpoint was 12-month primary patency, defined as peak systolic velocity ratio ≥2.5 by duplex ultrasound and compared against a prespecified performance goal of 60% based on established angioplasty data. RESULTS: The mean age was 73.8 ± 6.9 years, and 60.3% of patients had diabetes mellitus. The mean lesion length was 127.4 ± 59.7 mm, 17.2% were chronic total occlusions, and 47.8% involved the popliteal artery. Data on 12-month restenosis were available in 127 patients (94.8%). The 12-month primary patency rate was 87.9%, and the freedom from clinically driven target lesion revascularization (CD-TLR) was 97.0% per Kaplan-Meier estimate. The major adverse event rate was 6.7%, driven by 4 CD-TLRs and 5 deaths, none of which were related to the device or procedure. Ankle-brachial index data improved significantly from 0.73 ± 0.16 at baseline to 0.96 ± 0.14 at 30 days postprocedure and was sustained through 12 months (0.94 ± 0.13). CONCLUSIONS: The SELUTION SFA JAPAN trial demonstrated that a novel SELUTION SCB is a safe and effective treatment option for FP disease in symptomatic patients.

Deciphering Popliteal Artery Aneurysm Patient Diversity: Insights From a Cluster Analysis of the POPART Registry.

BACKGROUND: Popliteal artery aneurysms (PAAs) are the most common peripheral aneurysm. However, due to its rarity, the cumulative body of evidence regarding patient patterns, treatment strategies, and perioperative outcomes is limited. This analysis aims to investigate distinct phenotypical patient profiles and associated treatment and outcomes in patients with a PAA by performing an unsupervised clustering analysis of the POPART (Practice of Popliteal Artery Aneurysm Repair and Therapy) registry. METHODS AND RESULTS: A cluster analysis (using k-means clustering) was performed on data obtained from the multicenter POPART registry (42 centers from Germany and Luxembourg). Sensitivity analyses were conducted to explore validity and stability. Using 2 clusters, patients were primarily separated by the absence or presence of clinical symptoms. Within the cluster of symptomatic patients, the main difference between patients with acute limb ischemia presentation and nonemergency symptomatic patients was PAA diameter. When using 6 clusters, patients were primarily grouped by comorbidities, with patients with acute limb ischemia forming a separate cluster. Despite markedly different risk profiles, perioperative complication rates appeared to be positively associated with the proportion of emergency patients. However, clusters with a higher proportion of patients having any symptoms before treatment experienced a lower rate of perioperative complications. CONCLUSIONS: The conducted analyses revealed both an insight to the public health reality of PAA care as well as patients with PAA at elevated risk for adverse outcomes. This analysis suggests that the preoperative clinic is a far more crucial adjunct to the patient's preoperative risk assessment than the patient's epidemiological profile by itself.

The role of body mass index in high- and low-velocity trauma causing knee injury associated with popliteal artery lesions.

BACKGROUND: Among arterial traumas, osteoarticular traumas are particularly dangerous, and those involving the popliteal artery are associated with a high amputation rate. Despite representing a minority of arterial traumas, with an incidence that varies considerably by population and geographic location, traumatic lesions of the popliteal artery are challenging. This study aimed to verify the impact of body mass index (BMI) on arterial trauma damage and patient outcomes. METHODS: Data were retrospectively collected from the electronic medical reports of all patients with osteoarticular and vascular associated lesions treated in the emergency operating room at our institution between 1 January 2005 and 1 May 2022. Forty-one patients presented with lower limb arterial trauma (43.2%); popliteal artery lesions occurred in 11 of these patients (26.8%), who were eligible for inclusion in the study. The lesion mechanism was dislocation by high-velocity trauma in 9 patients and dislocation by low-velocity trauma in 3 patients. All 7 males (63.6%) experienced high-velocity trauma, and 2 of the 3 females experienced low-velocity trauma. Only one patient had an isolated popliteal artery lesion associated with fractures in the leg or the contralateral limb. Patients with low-velocity trauma were older than 54 years, while those with high-velocity trauma were aged 22 to 71 years. RESULTS: In 10/11 patients (90.9%), revascularization was performed after osteoarticular stabilization and reduction of the dislocation or fracture. Intraoperative angiography was selectively used. Two patients required above-the-knee amputation after the procedure: one due to infection of the surgical access point and the other due to severe soft tissue injury. One patient died during hospitalization due to trauma-related complications and comorbidities. CONCLUSIONS: High-velocity trauma and low-velocity trauma in patients with a body mass index > 35 kg/m2 and knee lesions are associated with popliteal artery lesions. Revascularization success is not associated with high- or low-velocity trauma.

An old but still valuable technique for popliteal artery stenosis: Endarterectomy via the posterior approach.

Isolated popliteal artery occlusions are rare compared with femoropopliteal occlusive diseases. Although endovascular procedures have gained importance in treatment, conventional surgery remains the gold standard. In this study, we reviewed popliteal endarterectomy and patch plasty using a posterior approach. Fourteen patients who underwent surgery for isolated popliteal artery occlusions were retrospectively examined. Patients were assessed in terms of age, sex, and risk factors, such as accompanying diseases and smoking, surgical method and anesthesia, incision type, preoperative and postoperative pulse examination, ankle-brachial indices, patency, wound infection, postoperative complications, and the treatment applied. Twelve (85.7%) patients were male, and 2 (14.3%) were female. Limb ischemia was critical (ABI < 0.7) in 11 (78.5%) patients. The average duration of postoperative hospitalization was 8 ±â€…3.7 days on average, and the average length of follow-up was 17 ±â€…3.4 months. Thrombosis and complications requiring secondary intervention did not develop during the early postoperative period. While the patency rate in the first 6 months of follow-up was 100%, it was 92.8% in the 1st year and 85.7% in the 2nd year. Surgical treatment with the posterior approach in isolated popliteal artery lesions is preferred by vascular surgeons as a prioritized treatment method, with a sufficient recanalization rate and low perioperative morbidity and mortality rates. Furthermore, it is promising because it does not prevent below-knee femoropopliteal bypass, which is the subsequent stage of treatment. Moreover, the great saphenous vein was protected, and the acceptable early- and mid-term results were encouraging.

Endovascular Transvenous versus Open Femoropopliteal Bypass.

Background and Objectives: Lower extremity arterial disease is one of the most prevalent manifestations of atherosclerosis. The results from numerous studies regarding the best revascularization method of an occluded superficial femoral artery have been conflicting. The aim of this study was to compare the patency of transvenous endovascular with open femoropopliteal bypass, both with vein and prosthetic grafts. To our knowledge, a direct patency comparison between transvenous endovascular and open femoropopliteal bypass has not been published. This could help elucidate which method is preferable and in which cases. Materials and Methods: Patients with complex TASC-C and D SFA lesions were offered endovascular transvenous or open bypass. A total of 384 consecutive patients with PAD requiring surgical treatment were evaluated for inclusion in this study. Three-year follow-up data were collected for 52 endovascular procedures, 80 prosthetic grafts, and 44 venous bypass surgeries. Bypass patency was investigated by Duplex US every 6 months. Kaplan-Meier plots were used to analyze primary, primary-assisted, and secondary patency for endovascular transvenous, autovenous, and prosthetic bypasses. Results: Primary, primary-assisted, and secondary patency in venous group at 3 years was 70.5%, 77.3%, and 77.3%, respectively. In the endovascular transvenous group, primary, primary-assisted, and secondary patency at 3 years was 46.2%, 69.2%, and 76.9%, respectively. The lowest patency rates at 3 years were noted in the prosthetic graft group with 22.5% primary, 26.6% primary-assisted, and 28.2% secondary patency. Conclusions: The saphenous vein is the best graft to perform in above-the-knee femoropopliteal bypass. Transvenous endovascular bypass is a viable option with comparable primary-assisted and secondary patency. Primary patency is substantially lower for endovascular transvenous compared to venous bypass. Patients treated with endovascular transvenous bypass will require a significant number of secondary procedures to provide optimal patency. Prosthetic grafts should only be used if no other option for bypass is available.

Disappointing results of popliteal aneurysm endovascular treatment with a new self-expandable covered stent.

PURPOSE: To describe our clinical experience of endovascular exclusion of popliteal artery aneurysms using the new self-expandable covered stent SOLARIS® (Scitech Medical, Brazil), and to report its results in the context of surgical and endovascular treatment of popliteal artery aneurysms. CASE REPORT: Among 20 popliteal artery aneurysms undergoing open or endovascular repair in 2022 and 2023, two patients were successfully treated with the Solaris stentgraft. Both patients had a patent popliteal artery and three run-off vessels. After stentgraft implantation, they received dual antiplatelet therapy for three months and they were followed-up with Duplex scan and clinical evaluation after three months, and every six months thereafter. After three months, one Solaris stentgraft had complete thrombosis and the other ruptured, requiring surgical removal. No complications were observed among the other aneurysms treated with open repair or with the Viabahn® stentgraft. CONCLUSIONS: Endovascular treatment of popliteal aneurysms with the new covered self-expandable stent Solaris resulted in severe complications in the two cases reported, and in worse short-term outcomes than endovascular repair with Viabahn® and open repair. Its off-label use to treat popliteal artery aneurysms should be therefore discouraged.

Randomized Trial Comparing a Stent-Avoiding With a Stent-Preferred Strategy in Complex Femoropopliteal Lesions.

BACKGROUND: Limited comparative data exist on different interventional strategies for endovascular revascularization of complex femoropopliteal interventions. OBJECTIVES: In this study, the authors aimed to compare a stent-avoiding (SA) vs a stent-preferred (SP) strategy, promoting optimal lesion preparation and the use of drug-eluting technologies in both arms. METHODS: Within a prospective, multicenter, pilot study, 120 patients with symptomatic complex femoropopliteal lesions (Rutherford classification 2-4, mean lesion length 187.7 ± 78.3 mm, 79.2% total occlusions) were randomly assigned in a 1:1 fashion to endovascular treatment with either paclitaxel-coated balloons or polymer-coated, paclitaxel-eluting stents. Lesion preparation including the use of devices for plaque modification and/or removal was at the operators' discretion in both treatment arms. RESULTS: In the SA group, lesion preparation was more frequently performed (71.7% SA [43/60] vs 51.7% [31/60] SP; P = 0.038) with a high provisional stenting rate (48.3% [29/60]). At the 12-month follow-up, primary patency was 78.2% (43/55) in the SA group and 78.6% (44/56) in the SP group (P = 1.0; relative risk: 0.995; 95% CI: 0.818-1.210). Freedom from major adverse events was determined in 93.1% (54/58) in the SA group and in 94.9% (56/59) in the SP group (P = 0.717; relative risk: 0.981; 95% CI: 0.895-1.075), with all adverse events attributable to clinically driven target lesion revascularization. CONCLUSIONS: Both endovascular strategies promoting lesion preparation before the use of drug-eluting devices suggest promising efficacy and safety results in complex femoropopliteal procedures with a high proportion of total occlusions through 12 months. Ongoing follow-up will show whether different results emerge over time. (Best Endovascular Strategy for Complex Lesions of the Superficial Femoral Artery [BEST-SFA]; NCT03776799).

Twenty-Four-Month Safety and Effectiveness of TCD-17187 Drug-Coated Balloon for Treatment of Atherosclerotic Lesions in Superficial Femoral and Proximal Popliteal Artery.

PURPOSE: In the present trial, the 24-month safety and effectiveness of the TCD-17187 drug-coated balloon (DCB) for the treatment of atherosclerotic lesions in the superficial femoral artery (SFA) and proximal popliteal artery (PA) were evaluated in Japanese patients. METHODS: This was a prospective, multicenter, core laboratory-adjudicated, single-arm trial. From 2019 to 2020, 121 patients with symptomatic peripheral artery disease were enrolled. The primary effectiveness outcome measure was primary patency. The safety outcome measure was the major adverse event (MAE) rate. RESULTS: Age was 74.5 ± 7.3 years, and diabetes mellitus was present in 67.5%. Lesion length and reference vessel diameter (RVD) were 106.0 ± 52.6 mm and 5.2 ± 0.8 mm, respectively. Chronic total occlusion (CTO) and bilateral calcification rate (Grade 3 and 4 by peripheral arterial calcium scoring system (PACSS)) were 17.5% and 50.8%, respectively. The 24-month primary patency rate by duplex ultrasound was 71.3%, while freedom from clinically driven target lesion revascularization (CD-TLR) was 87.0%. The MAE rate was 13.2% and all events consisted of CD-TLR. There were no instances of device- or procedure-related deaths major amputations throughout the 24 months. Multivariate Cox proportional hazards regression analysis revealed significant differences associated with loss of primary patency in the following characteristics: CTO, restenotic lesion and RVD. CONCLUSION: This trial confirmed the safety and effectiveness of TCD-17187 DCB for atherosclerotic lesions of the SFA and/or proximal PA for up to 24 months. LEVEL OF EVIDENCE: Level 3, Cohort study. CLINICAL TRIAL REGISTRATION: URL: https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&recptno=R000038612&type=summary&language=J:Registration ID: UMIN000034122. Registration Date: September 13, 2018.

Infrapopliteal Bypass In Patients On Dialysis: Patency And Survival.

INTRODUCTION: Portugal has one of the highest prevalence of patients on a regular dialysis program. This population has a higher incidence of peripheral arterial disease with higher rates of postoperative morbidity and mortality. Our goal was to compare outcomes between dialysis and non-dialysis patients with chronic limb threatening ischemia (CLTI) submitted to infrapopliteal bypass. MATERIALS AND METHODS: A retrospective single-center study of infrapopliteal bypass for CLTI was performed between 2012 and 2019. Patients were divided in two groups based on dialysis status (group 1 incorporated patients on dialysis). Primary end point was 1-year freedom from CLTI. Secondary end points were limb-salvage, survival and primary (PP) and tertiary patency (TP) rates at 3 years of follow-up. RESULTS: A total of 352 infrapopliteal bypasses were performed in 310 patients with CLTI. Fourteen percent of the revascularizations were performed on dialysis patients (48/352). Median age was 73 years (interquartile range - IQR 15) and 74% (259/352) were male. Median follow-up was 26 months (IQR 42). Overall, 92% (325/352) had tissue loss and 44% (154/352) had some degree of infection. The majority of revascularization procedures were performed with vein grafts (61%, 214/352). The 30-day mortality was 4% (11/310), with no difference between groups (p = 0.627). Kaplan-Meier analysis showed no difference between groups regarding freedom from CLTI (76% vs. 79%; HR 0.96, CI 0.65-1.44, p=0.857), limb-salvage (70% vs. 82%; HR 1.40, CI 0.71-2.78, p=0.327) and survival (62% vs. 64%; HR 1.08, CI 0.60-1.94, p=0.799). PP rates were 39% in group 1 and 64% in group 2 (HR 1.71, CI 1.05-2.79, p=0.030). TP rates were not different between groups (57% and 78%; HR 1.79, CI 0.92-3.47, p=0.082). CONCLUSION: Infrapopliteal bypass for CLTI, on dialysis patients, resulted in lower PP rates. No differences were observed in freedom from CLTI, TP, limb salvage and survival.

A rare case of epithelioid angiosarcoma.

Epithelioid angiosarcoma is a rare high-grade vascular neoplasm with a poor prognosis. We present an anticoagulated 77-year-old man, with a history of popliteal/soleal vein thrombosis in the previous month, complaining of ipsilateral persistent lower limb pain and claudication. Absent popliteal/distal pulses prompted an arterial doppler ultrasound (DUS), revealing thrombosis of the distal superficial femoral artery and a popliteal mass. As the arterial wall's integrity could not be appropriately evaluated by DUS, adventitial cystic disease of the popliteal artery was suspected. Computed tomography angiography and magnetic resonance imaging findings were also suggestive. Due to refractory pain, he was submitted to a popliteal mass excision along with a femoral-posterior tibial bypass. Pathology revealed an epithelioid angiosarcoma. He was referred to a Sarcoma Center, requiring hospitalization for agitation and fever. A positron emission tomography (PET) scan revealed extensive lower limb disease persistence and distant metastases. He died on the 56th day after surgery. To our knowledge, there are only 15 cases of angiosarcoma of the popliteal artery described in the literature. Ours stands out as the first one unrelated to a popliteal aneurysm. Being a highly-aggressive tumor, an early diagnosis is challenging but essential to a successful treatment, warranting the need for suspicion of this neoplasm. An early core biopsy or surgical sample may expedite the diagnosis.

Investigation of Optimal Needle Position for Radiofrequency Ablation-Based Blockade of Interspace between the Popliteal Artery and the Posterior Capsule of the Knee: A Cadaveric Study.

Background and Objectives: The interspace between the popliteal artery and the posterior capsule of the knee (iPACK) block has been widely used in perioperative settings to control posterior knee pain and can additionally be used for chronic knee pain. In this cadaveric study, we aimed to investigate the needle tip position and its proximity to the articular branch of the tibial nerve (ABTN) during an iPACK-targeted radiofrequency procedure. Materials and Methods: An ultrasound-guided iPACK block was performed on 20 knees of 10 cadavers. We injected 0.1 mL each of blue and green gelatinous dye near the tibial artery (point A) and posterior knee capsule (point B), respectively, and evaluated the spread of both around the ABTN. For a hypothetical conventional radiofrequency ablation (RFA) lesion (diameter, 2.95 mm) and cooled RFA lesion (diameter, 4.9 mm), we counted the number of specimens in which the ABTNs would be captured. Results: The percentage of specimens in which the ABTN would be captured by a cooled RFA lesion was 64.71% at point A and 43.75% at point B (p = 0.334). Meanwhile, the percentage of specimens in which the ABTN would be captured by a conventional RFA lesion was 58.82% from point A and 25% from point B (p = 0.065). Conclusions: When performing an RFA-based iPACK block, the needle tip may be positioned either lateral to the tibial artery or in the space between the posterior knee capsule and the tibial artery. However, more studies with larger samples are needed to verify these results before the clinical use of this procedure can be recommended.