The analgesic effect of ultrasound-guided cervical erector spinae block in arthroscopic shoulder surgery: a randomized controlled clinical trial.

BACKGROUND: Erector spinae plane block (ESPB) is a novel fascial plane block technique that can provide effective perioperative analgesia for thoracic, abdominal and lumbar surgeries. However, the effect of cervical ESPB on postoperative analgesia after arthroscopic shoulder surgery is unknown. The aim of this study is to investigate the analgesic effect and safety of ultrasound-guided cervical ESPB in arthroscopic shoulder surgery. METHODS: Seventy patients undergoing arthroscopy shoulder surgery were randomly assigned to one of two groups: ESPB group (n = 35) or control group (n = 35). Patients in the ESPB group received an ultrasound-guided ESPB at the C7 level with 30 mL of 0.25% ropivacaine 30 min before induction of general anesthesia, whereas patients in the control group received no block. The primary outcome measures were the static visual analogue scale (VAS) pain scores at 4, 12, and 24 h after surgery. Secondary outcomes included heart rate (HR) and mean arterial pressure (MAP) before anesthesia (t1), 5 min after anesthesia (t2), 10 min after skin incision (t3), and 10 min after extubation (t4); intraoperative remifentanil consumption; the Bruggrmann comfort scale (BCS) score, quality of recovery-15 (QoR-15) scale score and the number of patients who required rescue analgesia 24 h after surgery; and adverse events. RESULTS: The static VAS scores at 4, 12 and 24 h after surgery were significantly lower in the ESPB group than those in the control group (2.17 ± 0.71 vs. 3.14 ± 1.19, 1.77 ± 0.77 vs. 2.63 ± 0.84, 0.74 ± 0.66 vs. 1.14 ± 0.88, all P < 0.05). There were no significant differences in HR or MAP at any time point during the perioperative period between the two groups (all P > 0.05). The intraoperative consumption of remifentanil was significantly less in the ESPB group compared to the control group (P < 0.05). The scores of BCS and QoR-15 scale were higher in the ESPB group 24 h after surgery than those in the control group (P < 0.05). Compared to the control group, fewer patients in the ESPB group required rescue analgesia 24 h after surgery (P < 0.05). No serious complications occurred in either group. CONCLUSIONS: Ultrasound-guided cervical ESPB can provide effective postoperative analgesia following arthroscopic shoulder surgery, resulting in a better postoperative recovery with fewer complications. TRIAL REGISTRATION: Chictr.org.cn identifier ChiCTR2300070731 (Date of registry: 21/04/2023, prospectively registered).

Expediting the reversal of inferior alveolar nerve block anesthesia in children with photobiomodulation therapy.

In pediatric dentistry, complications arising from extended soft tissue anesthesia can negatively impact patient comfort and trust in dental care. This study evaluates the clinical efficacy of diode laser-based photobiomodulation therapy (PBMT) in expediting the resolution of anesthesia in children aged 6-9 receiving inferior alveolar nerve block (IANB) injections. In this split-mouth double-blind randomized clinical trial, 36 pediatric subjects aged 6-9, requiring pulpotomy procedures on both sides of the mandible, received IANBs (single cartridge of 2% lidocaine/1:100,000 epinephrine). PBMT and sham laser were alternately applied to each side of the mandible, in two separate sessions, with the envelope method determining treatment allocation and intervention side on the first treatment day. During the laser session, laser (808 nm, 250 mW, 23s continuous, 0.5 cm², 11.5 J/cm², direct contact) irradiated two points at the injection site, five intra-oral and five extra-oral points along the infra-alveolar nerve's pathway. Soft tissue anesthesia reversal was quantified through tactile assessment. Soft tissue trauma was also assessed by the researcher and reported by parents 24 h post-dental visit. All data were analyzed using IBM SPSS Statistics v25.0 via Paired T-test, two-way repeated measures ANOVA, and McNemar's test. The laser group exhibited a mean lip anesthesia duration of 122.78 ± 2.26 min, while the sham laser group experienced 134.44 ± 21.8 min, indicating an 11.66-minute reduction in anesthesia duration for the laser group. (P < 0.001) Soft tissue trauma occurred in two sham laser group patients and one laser group patient, with no significant difference. (P = 1) The findings indicate that employing laser with defined parameters can reduce the length of IANB-induced anesthesia.

Application of Hip Pericapsular Nerve Block Combined With Spinal Anesthesia in the Treatment of Elderly Patients With Femoral Intertrochanteric Fracture.

OBJECTIVE: To investigate the effect of pericapsular nerve group (PENG) block combined with spinal anesthesia in the treatment of elderly patients with intertrochanteric fractures through "rapid diagnosis and treatment channel" PFNA internal fixation. METHODS: 52 elderly patients were randomly divided into the observation group (26 patients, PENG block combined with spinal anesthesia) and the control group (26 patients, spinal anesthesia alone). The general health, mean arterial pressure (MAP), and heart rate (HR) of both groups were compared at various stages: immediately before the administration of pain analgesia, during the positioning of spinal epidural anesthesia, at the beginning and end of the surgery, and 2 hours after surgery. Additionally, VAS scores at rest and during passive straight leg elevation by 15° were evaluated at 12 hours, 24 hours, 48 hours, 72 hours, and 7 days after surgery. RESULTS: The MAP and HR in the observation group under spinal anesthesia in the lateral position were lower than those in the control group (P < 0.05). Additionally, the VAS scores of the observation group during positioning and at 12 hours and 24 hours after surgery were lower than those in the control group under spinal epidural anesthesia (both P < 0.05). CONCLUSION: The application of ultrasound-guided PENG block combined with lumbar anesthesia can reduce pain when in lateral position, stabilize perioperative vital signs, and result in high satisfaction.

Erector spinae plane block versus paravertebral block on postoperative quality of recovery in obese patients undergoing laparoscopic sleeve gastrectomy: a randomized controlled trial.

Purpose: To compare the impact of erector spinae plane block (ESPB) and paravertebral block (PVB) on the quality of postoperative recovery (QoR) of patients following laparoscopic sleeve gastrectomy (LSG). Methods: A total of 110 patients who underwent elective LSG under general anesthesia were randomly assigned to receive either ultrasound-guided bilateral ESPB or PVB at T8 levels. Before anesthesia induction, 40 mL of 0.33% ropivacaine was administered. The primary outcome was the QoR-15 score at 24 hours postoperatively. Results: At 24 hours postoperatively, the QoR-15 score was comparable between the ESPB and PVB groups (131 (112-140) vs. 124 (111-142.5), P = 0.525). Consistently, there was no significant difference in QoR-15 scores at 48 hours postoperatively, numerical rating scale (NRS) pain scores at any postoperative time points, time to first ambulation, time to first anal exhaust, postoperative cumulative oxycodone consumption, and incidence of postoperative nausea and vomiting (PONV) between the two groups (all P > 0.05). No nerve block-related complications were observed in either group. Conclusion: In patients undergoing LSG, preoperative bilateral ultrasound-guided ESPB yields comparable postoperative recovery to preoperative bilateral ultrasound-guided PVB.

Efficacy of Ropivacaine for Sub-Arachnoid Block in Patients with Recent History of Scorpion Sting: A case series.

Failure of sub-arachnoid block (SAB), due to resistance to bupivacaine after a recent scorpion sting can lead to multiple block attempts and subsequent conversion to general anaesthesia. We report this case series of 10 patients with successful SAB with newly launched 0.75% hyperbaric ropivacaine, in patients with recent scorpion sting. Thus, intrathecal hyperbaric ropivacaine may be considered as the local anaesthetic agent of choice in patients with scorpion sting to prevent failure of SAB.

The Medipol Combination: Novel Rectointercostal Fascial Plane Block and Pectointercostal Fascial Plane Block for Postoperative Analgesia Management After Cardiac Surgery: A Report of 15 Cases.

The parasternal blocks cannot cover the T7 and lower anterior and lateral branches of the thoracoabdominal nerves. In the open heart surgeries, chest drainage tubes are generally outside the target of the parasternal blocks. Recently, Tulgar et al described a novel interfascial plane block technique named "recto-intercostal fascial plane block" (RIFPB). RIFPB is performed between the rectus abdominis muscle and the sixth to seventh costal cartilages. RIFPB targets the anterior and lateral cutaneous branches of the T6-T9 thoracoabdominal nerves. In this clinical report, we want to share our experiences about pectointercostal plane block and RIFPB combination (Medipol Combination) after cardiac surgery.

Predictors of a Successful Outcome Following a Thoracic Erector Spinae Plane Block for Cervical Radiculopathy.

BACKGROUND: The erector spinae plane block (ESPB) is an interfascial plane block for managing neuropathic thoracic pain. Although the ESPB is applied widely in various clinical situations, no studies have evaluated the association between the analgesic outcomes of the ESPB and the numerical changes in the perfusion index (PI) and PI ratio. OBJECTIVES: The purpose of this study is to investigate the association between the clinical response following ESPB and other possible factors, including changes in the PI and PI ratio. STUDY DESIGN: A prospective, nonrandomized, and open-label study. SETTING: The pain clinic of a tertiary university hospital. METHODS: This study included 92 patients with neck or arm pain who received T2 ESPB using 20 mL of 0.2% ropivacaine. To aid in the prediction of clinical outcomes, the PI was measured at the blocked side for 30 minutes as soon as the ESPB was finished. Various demographic data were also analyzed to predict the clinical outcomes. RESULTS: Among 92 patients, 59 patients (64%) showed successful treatment outcomes (> 50% reduction in the numerical rating scale score or > 30% reduction in the neck disability index). The baseline PI of the responders was statistically higher than the nonresponders' (P < 0.05). Also, the responders' PI demonstrated statistically higher values than the nonresponders' at the time points of 4, 6, and 8 minutes after the ESPB. Multivariate logistic regression analysis revealed that a higher baseline PI (OR, 1.91; 95% CI, 1.27-2.86; P = 0.002) was an independent factor associated with a successful outcome. LIMITATIONS: Only a small number of patients with nonspinal diseases were included, except for those who had cervical radiculopathy. Therefore, it is hard to conclude that thoracic ESPB has any therapeutic benefits to patients with nonspinal diseases such as complex regional pain syndrome, adhesive capsulitis, or post-thoracotomy pain syndrome. CONCLUSION: A successful outcome at 4 weeks after T2 ESPB was achieved in 64% of patients with cervical radiculopathy. A higher baseline PI value was an independent factor associated with a successful response to T2 ESPB.

Ultrasound-assisted Thoracic Intervertebral Foramen Block. A Cadaveric Study.

BACKGROUND: A thoracic paravertebral block can be a useful opioid-sparing technique for controlling postoperative pain after thoracic and visceral abdominal surgery. OBJECTIVES: Our aim was to assess dye spread into the ventral branch, connecting branch, sympathetic trunk, thoracic paravertebral space, and epidural space after performing a modified ultrasound-assisted thoracic paravertebral block via the intervertebral foramen. STUDY DESIGN: This was a nonrandomized cadaveric study. SETTING: The cadavers were kept at the Department of Anatomopathology of the San Salvatore Academic Hospital of L'Aquila (L'Aquila, Italy). METHODS: We performed a bilateral thoracic paravertebral block via the intervertebral foramen at the second, fifth, ninth, and twelfth thoracic vertebrae. A linear array ultrasound transducer was used. Then, cadaveric dissection was performed. A Tuohy needle was gently inserted in-plane with the ultrasound beam in a lateromedial direction to contact the spinous process. Subsequently, the needle tip was advanced 2 mm along the transverse process of the vertebra, and 5 mL of methylene blue 1% dye was injected at each level. Then, 2 continuous catheter sets were inserted. RESULTS: Forty intervertebral foramen blocks were performed in 5 cadavers. For 38 injection sites, we found dye on both sides of the thoracic paravertebral space and epidural space at each level of puncture. The retropleural organs were also stained. In 2 cases, methylene blue accumulated intramuscularly at the level of the twelfth thoracic vertebra. RESULTS: The spread of dye into the ventral rami, communicating rami, and sympathetic trunk in the thoracic paravertebral space and the epidural space was assessed. We also evaluated the position and the distance (mm) between the catheter tip and the thoracic intervertebral foramen content. Finally, puncturing of intervertebral blood vessels, nerve rootlet and root damage, lung and pleural injuries, and the extent of intramuscular dye accumulation were evaluated and recorded as iatrogenic complications related to the anesthetic procedure. Forty thoracic paravertebral blocks in 5 cadavers were performed. For 38 injection sites, we found dye on both sides of the thoracic paravertebral space and the epidural space at each level of puncture. The ventral rami, the communicating rami, and the sympathetic trunk were also stained. In 2 cases, methylene blue accumulated intramuscularly at the level of the twelfth thoracic vertebra. LIMITATIONS: The first limitation of this study is its small sample size. In addition, the study design did not consider or measure the width of the transverse processes. Another limitation is that the ultrasound beam could not identify the thoracic intervertebral foramen content or the needle tip behind the acoustic shadow of the transverse and vertebral articular processes. CONCLUSION: Paravertebral block via the thoracic intervertebral foramen achieved consistent dye spread into the thoracic paravertebral space and epidural space, capturing retropleural organs.

FEASIBILITY AND EFFECTIVENESS OF GENERAL ANESTHESIA WITH OPIOIDS VERSUS OPIOID-FREE ANESTHESIA PLUS TRANSVERSUS ABDOMINIS PLANE BLOCK ON POSTOPERATIVE OUTCOMES AFTER MINI GASTRIC BYPASS SURGERY.

Opioid-free anesthesia (OFA) is increasingly used at present in surgical practice by many hospitals as a new and very promising anesthesiologic regimen. This study aimed to compare the efficacy of standard general anesthesia with opioids with so-called opioid-free anesthesia on postoperative outcomes of patients who underwent gastric bypass surgery. This randomized, single-blind clinical study enrolled 103 patients scheduled for elective gastric bypass surgery. They were assigned randomly to receive either general anesthesia without opioids plus transversus abdominis plane (TAP) block (Group 1: 53 patients) or general anesthesia with opioids (Group 2: 50 patients). 21.4% (22/103) males and 78.6% (81/103) females were operated. The average age of patients was 40.9 and the average BMI - 48.4. Patients from both groups (patients who received general anesthesia + TAP and patients who received general anesthesia with opioids) were assessed for postoperative pain at rest using a 0-to-10 visual analog pain scale (0 = no pain, 5 = moderate pain, and 10 = the most severe pain possible). In group 1 - 34% (18/53) of patients did not receive any medication against pain and 66% (35/53) received Dexalgin Inject 25mg/ml 2 ml. There was no need in opioids. In group 2 - 10% (5/50) of patients did not receive any medication against pain, 38% (19/50) received Dexalgin Inject 25mg/ml 2 ml and 52% (26/50) received Dexalgin Inject 25mg/ml 2 ml + Promedol 20mg/ml 1ml. Type of anesthesia is a significant predictor of postoperative outcomes, such as pain intensity, extubation time, intensive care stay, and hospital length of stay in patients undergoing gastric bypass surgery. Patients, who received (OFA) plus (TAP) block had better pain control than those who received general anesthesia with opioids. No opioids were used in group 1. In addition, the duration of hospital stay in group 1 was shorter, and the average cost for postoperative hospital stay was 2.39 times lower than in group 2. OFA can be used as a reliable and effective anesthesiologic technique in patients scheduled for bariatric surgery.

Ultrasound-guided erector spinae nerve block for relief of chest pain from pneumonia in the emergency department.

Erector spinae plane blocks (ESPB) have shown to provide meaningful chest wall anesthesia and reduce opioid consumption after thoracic surgery. Emergency physicians often use erector spinae plane blocks in the emergency department (ED) for rib fractures when acetaminophen, non-steroidal anti-inflammatory (NSAID), and opioids fail to control pain. They have also demonstrated successful pain management for conditions like herpes zoster, renal colic, burns, and acute pancreatitis for ED patients. With low reported rates of complication and relatively easy landmarks to identify, erector spinae plane blocks are an appealing regional anesthetic technique for emergency physicians to utilize for uncontrolled pain. We present the case of a 58-year-old male presenting to the ED with chest pain from pneumonia which remained unmanageable after acetaminophen, NSAID, and opioid administration. An ultrasound-guided erector spinae plane block was performed in the ED and the patient had a significant reduction in his chest pain.

Anesthesia for the Patient Undergoing Shoulder Surgery.

Shoulder surgery introduces important anesthesia considerations. The interscalene nerve block is considered the gold standard regional anesthetic technique and can serve as the primary anesthetic or can be used for postoperative analgesia. Phrenic nerve blockade is a limitation of the interscalene block and various phrenic-sparing strategies and techniques have been described. Patient positioning is another important anesthetic consideration and can be associated with significant hemodynamic effects and position-related injuries.

Regional Anesthesia for Athletes Undergoing Upper Extremity Procedures: Techniques and Considerations.

Upper extremity injuries are frequent in athletes which may require surgeries. Regional anesthesia for postoperative analgesia is important to aid recovery, and peripheral nerve blocks for surgical anesthesia enable surgeries to be performed without general anesthetics and their associated adverse effects. The relevant nerve block approaches to anesthetize the brachial plexus for elbow, wrist and hand surgeries are discussed in this article. There is very limited margin for error when performing nerve blocks and multimodal monitoring approach to reduce harm are outlined. Lastly, the importance of obtaining informed consent prior to nerve block procedures should not be overlooked.

Determination of the optimal position of the lower extremity for femoral nerve block with ultrasonographic measurements: a prospective volunteer-based study.

OBJECTIVE: The aim of the study was to determine the optimal position for femoral nerve block (FNB) under ultrasound guidance. PATIENTS AND METHODS: We included fifty volunteers between 18-65 years of age in this study. The distances from the skin to the landmarks, which were taken as a reference for the ultrasound-guided FNB (apex point of the femoral artery = F12, lateral point = F9, and lower point = F6), were measured and compared in 3 different positions given to the lower extremity (neutral position: P1, 45° abduction: P2, and flexed knee: P3). The ease of application and the quality of the ultrasound images were evaluated at each measurement by assigning a subjective observer score and comparing them in three positions. RESULTS: All three measurement points were found to be closest to the skin at position P3. However, the distances from F9 (p = 0.023) and F6 (p = 0.006) to the skin were significant. A significant difference was found between P1 and P3 in terms of the distance from F9 (p = 0.027) and F6 to the skin (p = 0.007). P3 was determined to be the position with the highest score for clarity of the ultrasonography images and ease of detection of the measurement points (p < 0.001). As the scores of ease of access to the femoral nerve (FN) and image clarity increased, the distance from the measurement point to the skin surface decreased, which was statistically significant. CONCLUSIONS: The ideal position for ultrasound-guided FNB is the P3 position. As an alternative for patients with limited mobility, the P2 position can be used.

The impact of ultrasound-guided erector spinae plane block on hemodynamic stability and postoperative pain in patients undergoing modified radical mastectomy for breast cancer.

OBJECTIVE: Breast cancer, a prevalent global malignancy in women, necessitates a comprehensive treatment approach, with surgery playing a crucial role. Severe acute pain is common post-radical breast cancer surgery, emphasizing the significance of hemodynamic stability and postoperative pain control for optimal outcomes. This study evaluates the impact of ultrasound-guided erector spinae plane block (ESPB) on these parameters in ASA scores 1-2 patients undergoing modified radical breast cancer surgery with general anesthesia. PATIENTS AND METHODS: Forty-eight patients were divided into two groups: a general anesthesia group, with erector spinae plane block (GA+ESPB), and a control group receiving only general anesthesia (GA). Hemodynamic parameters were continuously monitored, and postoperative pain was assessed using the visual analog scale (VAS) at various time points. RESULTS: Ultrasound-guided ESPB effectively maintained hemodynamic stability and reduced postoperative pain in breast cancer surgery patients. Statistically significant differences were observed in heart rate, systolic and diastolic blood pressure, and mean arterial pressure between the GA and GA+ESPB groups at multiple time points (p < 0.05). VAS scores showed a significant interaction time*group (p < 0.001), with consistent differences between the groups at all time points (p ≤ 0.001). CONCLUSIONS: Ultrasound-guided ESPB application proved effective in preserving hemodynamic stability and managing postoperative pain in modified radical breast cancer surgery. The technique demonstrates promise in minimizing complications related to hemodynamic variations and postoperative pain, contributing to a comprehensive approach to breast cancer surgical treatment.

Cryoablation Catheter Used in the Surgical Treatment of Atrial Fibrillation May Treat Chest Tube Pain: Engin Technique.

Postoperative pain after cardiac surgery plays an important role in the patient's recovery process. In particular, pain at the chest tube site can negatively affect the comfort and recovery of these patients. Effective pain control minimizes the risk of many complications. Oral and intravenous analgesics, epidural anesthesia, paravertebral block, and intercostal nerve blockade are used in chest tube pain control. We routinely use the surgical cryoablation method in the presence of atrial fibrillation in the preoperative period of cardiac surgery in our clinic. Here we aimed to describe our method of using the cryoablation catheter for intercostal nerve blockade.

[Comparison of the effects of sciatic nerve block combined with continuted femoral nerve block or continuted adductor canal block on pain and motor function after total knee arthroplasty].

Objective: To compare the effect of sciatic nerve block (SNB) combined with continuted femoral nerve block (FNB) or continuted adductor canal block (ACB) on pain and motor function after total knee arthroplasty (TKA). Methods: A total of 60 patients with TKA-treated osteoarthritis of the knee who met the selection criteria were enrolled between November 2020 and February 2021 and randomised allocated into the study group (SNB combined with continuted ACB) and the control group (SNB combined with continuted FNB), with 30 cases in each group. There was no significant difference in gender, age, body mass, height, body mass index, preoperative Hospital for Special Surgery (HSS) score, femoral tibial angle, and medial proximal tibial angle between the two groups ( P>0.05). The operation time, the initial time to the ground, the initial walking distance, and the postoperative hospital stay were recorded. At 2, 4, 6, 12, 24, and 48 hours after operation, the numerical rating scale (NRS) score was used to evaluate the rest pain around the knee joint, the quadriceps femoris muscle strength was evaluated by the freehand muscle strength method, and the knee flexion and extension angles were measured. Results: There was no significant difference in the operation time and initial walking distance between the two groups ( P>0.05); the initial time to the ground and postoperative hospital stay of the study group were significantly shorter than those of the control group ( P<0.05). Except for the 48-hour postoperative NRS score of the study group, which was significantly lower than that of the control group ( P<0.05), there was no significant difference in the NRS scores between the two groups at the remaining time points ( P>0.05). The quadriceps femoris muscle strength from 4 to 24 hours postoperatively and the knee extension angle from 2 to 6 hours postoperatively of the study group were significantly better than those of the control group ( P<0.05); the differences in the quadriceps femoris muscle strength and knee extension and flexion angles between the two groups at the remaining time points were not significant ( P>0.05). Conclusion: SNB combined with either continuted ACB or continuted FNB can effectively relieve pain in patients after TKA, and compared with combined continuted FNB, combined continuted ACB has less effect on quadriceps femoris muscle strength, and patients have better recovery of knee flexion and extension mobility.

Effectiveness of Peripheral Nerve Block in Terms of Search for a Standardized Treatment Protocol in Diabetic Foot Patients Using Anticoagulants: A Double-Center Study.

BACKGROUND: Lower-extremity amputation for a diabetic foot is mainly performed under general or central neuraxial anesthesia. Ultrasound-guided peripheral nerve block (PNB) can be a good alternative, especially for patients who require continuous anticoagulation treatment and patients with additional comorbidities. We evaluated bleeding due to PNB application in patients with diabetic foot receiving antiplatelet or anticoagulant therapy. Perioperative morbidity and mortality and the need for intensive care hospitalization were analyzed. METHODS: This study included 105 patients with diabetic foot or debridement who underwent distal foot amputation or debridement between February and October 2020. Popliteal nerve block (17 mL of 5% bupivacaine and 3 mL of saline) and saphenous nerve block (5 mL of 2% lidocaine) were applied to the patients. Postoperative pain scores (at 4, 8, 12, and 24 hours) and complications due to PNB were evaluated. Intensive care admission and 1-month mortality were recorded. RESULTS: The most common diseases accompanying diabetes were hypertension and peripheral artery disease. No complications due to PNB were observed. Mean ± SD postoperative first analgesic need was determined to be 14.1 ± 4.1 hours. Except for one patient, this group was followed up without the need for postoperative intensive care. In 16 patients, bleeding occurred as leakage from the surgical area, and it was stopped with repeated pressure dressing. Mean ± SD patient satisfaction score was 8.36 ± 1.59. Perioperative mortality was not observed. CONCLUSIONS: Ultrasound-guided PNB can be an effective and safe anesthetic technique for diabetic patients undergoing distal foot amputation, especially those receiving antiplatelet or anticoagulant therapy and considered high risk.

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.