A meta-analysis on advantages of peripheral nerve block post-total knee arthroplasty

Integrating mechanistic-based and classification-based concepts into perioperative pain management: an educational guide for acute pain physicians

Chronic pain begins with acute pain. Physicians tend to classify pain by duration (acute vs chronic) and mechanism (nociceptive, neuropathic and nociplastic). Although this taxonomy may facilitate diagnosis and documentation, such categories are to some degree arbitrary constructs, with significant overlap in terms of mechanisms and treatments. In clinical practice, there are myriad different definitions for chronic pain and a substantial portion of chronic pain involves mixed phenotypes. Classification of pain based on acuity and mechanisms informs management at all levels and constitutes a critical part of guidelines and treatment for chronic pain care. Yet specialty care is often siloed, with advances in understanding lagging years behind in some areas in which these developments should be at the forefront of clinical practice. For example, in perioperative pain management, enhanced recovery protocols are not standardized and tend to drive treatment without consideration of mechanisms, which in many cases may be incongruent with personalized medicine and mechanism-based treatment. In this educational document, we discuss mechanisms and classification of pain as it pertains to commonly performed surgical procedures. Our goal is to provide a clinical reference for the acute pain physician to facilitate pain management decision-making (both diagnosis and therapy) in the perioperative period.

Patient-Controlled Analgesia and Peripheral Nerve Block Increase the Risk of Post-operative Urinary Retention after Total Knee Arthroplasty in Asian Patients

Introduction

Post-operative urinary retention (POUR) is a common complication after total knee arthroplasty (TKA) and may result in severe complications such as urinary tract infection and deep joint sepsis, leading to prolonged hospital stay and increased medical costs. Hence a retrospective study was performed to identify the incidence and modifiable factors associated with POUR after elective TKA in Asian patients with the aim to prevent POUR and its undesirable consequences.

Materials and Methods

The medical records of 496 consecutive patients who underwent elective TKA between 1 August 2017 and 30 July 2018 were reviewed. There were 154 male (31.0%) and 342 female (69.0%) patients with an average age of 68 years old. The incidence of POUR was analysed with respect to various modifiable and non-modifiable risk factors, including patient demographics, medical comorbidities, duration of surgery, type of intra-operative anaesthesia and post-operative analgesia and early initiation of physiotherapy using univariate and multivariate analyses.

Results

A total of 120 (24.2%) of the 496 patients who underwent elective TKA developed POUR. The odds of a patient with patient-controlled analgesia (PCA) and peripheral nerve block (PNB) developing POUR were 4.2 times and 4.7 times that of a patient without PCA and PNB, respectively. Age, male gender and type of anaesthesia were not found to be significant.

Conclusion

In our study population, the incidence of POUR after elective TKA was 24% with major modifiable risk factors being associated with the use of PCA and PNB as post-operative anaesthesia. POUR can have deleterious effects thus alternative post-operative analgesia should be considered.

[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.

A Network Meta-Analysis of Randomized Controlled Trials Assessing Intraoperative Anesthetic Therapies for Analgesic Efficacy and Morphine Consumption Following Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to compare intraoperative anesthetic therapies for total knee arthroplasty (TKA) regarding postoperative analgesic efficacy and morphine consumption by conducting a systematic literature search.

METHODS

Randomized controlled trials of TKA using various anesthetic therapies were identified from various databases from conception through December 31, 2021. A network meta-analysis of relevant literature was performed to investigate which treatment showed better outcomes. In total, 40 trials were included in this study.

RESULTS

Surface under the cumulative ranking curve showed local infiltration anesthesia (LIA) with saphenous nerve block (SNB) to produce the best pain relief on postoperative days (PODs) 1 and 2 and the best reduction of morphine consumption on PODs 1 and 3. However, femoral nerve block showed the largest effect on pain relief on POD 3, and liposomal bupivacaine showed the largest effect on reduction of morphine consumption on POD 2.

CONCLUSIONS

According to this network meta-analysis, surface under the cumulative ranking curve percentage showed that LIA with SNB provided the best analgesic effect after TKA. Furthermore, patients receiving LIA with SNB had the lowest consumption of morphine. Although femoral nerve block resulted in better pain relief on POD 3, LIA with SNB could be selected first when trying to reduce morphine consumption or increase early ambulation.

New insight into the vasto-adductor membrane for safer adductor canal blockade

Background

: This study aimed to identify exact anatomical landmarks and ideal injection volumes for safe adductor canal blocks (ACB).

Methods

: Fifty thighs from 25 embalmed adult Korean cadavers were used. The measurement baseline was the line connecting the anterior superior iliac spine (ASIS) to the midpoint of the patellar base. All target points were measured perpendicular to the baseline. The relevant cadaveric structures were observed using ultrasound (US) and confirmed in living individuals. US-guided dye injection was performed to determine the ideal volume.

Results

: The apex of the femoral triangle was 25.3 ± 2.2 cm distal to the ASIS on the baseline and 5.3 ± 1.0 cm perpendicular to that point. The midpoint of the superior border of the vasto-adductor membrane (VAM) was 27.4 ± 2.0 cm distal to the ASIS on the baseline and 5.0 ± 1.1 cm perpendicular to that point. The VAM had a trapezoidal shape and was connected as an aponeurosis between the medial edge of the vastus medialis muscle and lateral edge of the adductor magnus muscle. The nerve to the vastus medialis penetrated the muscle proximal to the superior border of the VAM in 70% of specimens. The VAM appeared on US as a hyperechoic area connecting the vastus medialis and adductor magnus muscles between the sartorius muscle and femoral artery.

Conclusions

: Confirming the crucial landmark, the VAM, is beneficial when performing ACB. It is advisable to insert the needle obliquely below the superior VAM border, and a 5 mL injection is considered sufficient.

A Retrospective Comparison of Clinical Efficacy between Multimodal Analgesia and Patient-Controlled Epidural Analgesia in Patients Undergoing Total Knee Arthroplasty

Background and Objectives: Adequate pain management during early rehabilitation is mandatory for improving the outcomes of patients undergoing total knee arthroplasty (TKA). Conventional pain management, mainly comprising opioids and epidural analgesia, may result in certain adverse effects such as dizziness, nausea, and motor blockade. We proposed a multimodal analgesic (MA) strategy involving the use of peripheral nerve block (NB), periarticular injection (PAI), and intravenous patient-controlled analgesia (IVPCA). This study compared the clinical efficacy and adverse effects of the proposed MA strategy and patient-controlled epidural analgesia (PCEA). Materials and Methods: We enrolled 118 patients who underwent TKA under spinal anesthesia. The patients followed either the MA protocol or received PCEA after surgery. The analgesic effect was examined using a numerical rating scale (NRS). The adverse effects experienced by the patients were recorded. Results: A lower proportion of patients in the MA group experienced motor blockade (6.45% vs. 22.98%) compared to those in the PCEA group on the first postoperative day. Furthermore, a lower proportion of patients in the MA group experienced numbness (18.52% vs. 43.33%) than those in the PCEA group on the first postoperative day. Conclusions: The MA strategy can be recommended for reducing the occurrence of motor blockade and numbness in patients following TKA. Therefore, the MA strategy ensures early rehabilitation while maintaining adequate pain relief.

Assessment of patellar cartilage cross-sectional area in patients with lower grade chondromalacia patella

Chondromalacia patella (CMP) is abnormal softening of the cartilage of the underside the patella. It is a cause of anterior knee pain. Previous study has demonstrated that the patellar cartilage hypertrophy is correlated with early signs of CMP (Grade 1 or 2). However, no studies have investigated the clinical cutoff value of patella cartilage hypertrophy. Thus, we devised the patellar cartilage cross-sectional area (PCCSA) as a new predictive parameter for diagnosing the CMP. The purpose of this research was to compare MR measured PCCSA between CMP patients and gender matched healthy controls. The PCCSA samples were collected from 50 patients with CMP, and from 50 healthy controls who underwent knee MRI with no evidence of CMP. The T2-weighted turbo spin echo transverse MRI images were acquired. We measured the PCCSA on MRI using a PACS system. The PCCSA was measured on the axial angled sections through the whole images by drawing outlines. The average PCCSA was 104.28 ± 23.28 mm2 in the healthy controls and 134.09 ± 26.55 mm2 in the CMP group. CMP patients had significantly higher PCCSA (P < .001). Regarding the validity of PCCSA as predictors of CMP, Receiver Operating Characteristic curve analysis showed that the best cutoff point for the PCCSA was 116.24 mm2, with 72.0% sensitivity, 72.0% specificity, and the area under curve (AUC) of 0.79 (0.71-0.88). The PCCSA is a sensitive measurement parameter to predict low grade CMP. Thus, to evaluate CMP patients, the treating physician carefully inspect the PCCSA.

Anatomical and Radiological Assessments of Injectate Spread Stratified by the Volume of the Pericapsular Nerve Group Block

BACKGROUND

The pericapsular nerve group (PENG) block was recently suggested as a regional technique for managing acute pain after hip surgery. However, few anatomical studies have confirmed the spread of injectate during the PENG block. This cadaver study aimed to analyze injectate spread to the target nerves during single-injection ultrasound-guided PENG block.

METHODS

Ultrasound-guided PENG block with 3 different injectate volumes (10, 20, or 30 mL) was performed in 18 cadavers. Injectate spread by the volume was first evaluated on computed tomography, followed by cadaver dissection. The spread of the dye over the pelvis and lower limb was evaluated.

RESULTS

The articular branches of the femoral nerve were stained nearly sufficiently with 20- and 30-mL specimens. The femoral nerve itself was stained simultaneously in six of 12 (50%) 20-mL specimens and 12 of 12 (100%) 30-mL specimens. The accessory obturator nerve was observed only in three (9%) of 36 specimens. The articular branches of the obturator nerve were rarely affected, regardless of injectate volume (1/12, 10 mL specimens; 2/12, 20 mL specimens; 1/12, 30 mL specimens; P > .999). Rather, the obturator nerve was affected. However, the obturator nerve was not stained consistently even with 30 mL of injectate (50%).

CONCLUSIONS

After combining the dissection and radiological findings, the single-injection ultrasound-guided PENG blocks with volumes of 10, 20, and 30 mL do not support motor sparing or selective anterior hip capsule innervation in a clinical setting. If early rehabilitation is needed, high-volume PENG block might not be the ideal option, and persisting pain after PENG block might be attributed in part to the lack of obturator nerve articular branches blockade.

Minimum effective volume of ropivacaine for ultrasound-guided adductor canal + IPACK block in total knee arthroplasty: A double-blind, randomized dose-finding trial

BACKGROUND

Our previous study reported that when a respective 20 mL of ropivacaine was used for adductor canal block (ACB) combined with infiltration between the popliteal artery and capsule of the posterior knee (IPACK) block for patients undergoing total knee arthroplasty (TKA), the minimum concentration of 0.275% could provide successful block in almost all patients. Based on the results, the primary objective of this study was to investigate the minimum effective volume (MEV₉₀, defined as the volume which can provide successful block in 90% of patients) of ACB + IPACK block.

METHODS

This double-blind, randomized dose-finding trial was based on a biased coin up-and-down sequential design, where the volume of ropivacaine administered to a given patient depended on the previous patient's response. The first patient received 15 mL of 0.275% ropivacaine for ACB and again for IPACK. If the block failed, the next subject received a 1 mL higher volume for ACB and IPACK, respectively; otherwise, the next subject received either a 1 mL lower volume (probability of 0.11) or the same volume (probability of 0.89). The primary outcome was whether the block was successful. Block success was defined as the patient did not suffer significant pain and did not receive rescue analgesia within 6 h after surgery. Then the MEV₉₀ was estimated by isotonic regression.

RESULTS

Based on analysis of 53 patients, the MEV₉₀ was 17.99 mL (95% CI 17.47-18.61 mL), MEV₉₅ was 18.48 mL (95% CI 17.45-18.98 mL) and MEV₉₉ was 18.90 mL (95% CI 17.38-19.07 mL). Patients whose blocks succeeded had significantly lower NRS pain scores, lower morphine consumption, and shorter hospitalization.

CONCLUSION

0.275% ropivacaine in 17.99 mL respectively can provide successful ACB + IPACK block in 90% of patients undergoing TKA. The minimum effective volume (MEV₉₀) of ACB + IPACK block was 17.99 mL.

Efficacy and Side Effect Profile of Intrathecal Morphine versus Distal Femoral Triangle Nerve Block for Analgesia following Total Knee Arthroplasty: A Randomized Trial

(1) Background: The management of postoperative pain after knee replacement is an important clinical problem. The best results in the treatment of postoperative pain are obtained using multimodal therapy principles. Intrathecal morphine (ITM) and single-shot femoral nerve block (SSFNB) are practiced in the treatment of postoperative pain after knee replacement, with the most optimal methods still under debate. The aim of this study was to compare the analgesic efficacy with special consideration of selected side effects of both methods. (2) Materials and methods: Fifty-two consecutive patients undergoing knee arthroplasty surgery at the Department of Orthopedics and Traumatology of the Medical University of Warsaw were included in the study. Patients were randomly allocated to one of two groups. In the ITM group, 100 micrograms of intrathecal morphine were used, and in the SSFNB group, a femoral nerve block in the distal femoral triangle was used as postoperative analgesia. The other elements of anesthesia and surgery did not differ between the groups. (3) Results: The total dose of morphine administered in the postoperative period and the effectiveness of pain management did not differ significantly between the groups (cumulative median morphine dose in 24 h in the ITM group 31 mg vs. SSFNB group 29 mg). The incidence of nausea and pruritus in the postoperative period differed significantly in favor of patients treated with a femoral nerve block. (4) Conclusions: Although intrathecal administration of morphine is similarly effective in the treatment of pain after knee replacement surgery as a single femoral triangle nerve block, it is associated with a higher incidence of cumbersome side effects, primarily nausea and pruritus.

Injectable electrospun fiber-hydrogel composite sequentially releasing clonidine and ropivacaine for prolonged and walking regional analgesia

Rationale: Peripheral nerve block is a traditional perioperative analgesic method for its precise pain control and low systemic toxicity. However, a single low dose of local anesthetic merely provides a few hours of analgesia, and high dose results in irreversible toxicity, whereas continuous infusion of anesthetics is expensive and complicated. Therefore, it is necessary to develop a long-acting and sensory-selective local anesthetic for safe perioperative analgesia. Methods: An injectable composite comprising ropivacaine-loaded poly (ε-caprolactone) electrospun fiber and clonidine-loaded F127 hydrogel (Fiber-Rop/Gel-Clo composite) was developed for long-acting and walking regional analgesia with barely one dose. The peripheral nerve blockade effect of the composite was evaluated in a rat sciatic nerve block model. Also, the biodegradability and biosafety of the composite was evaluated. Results: The preferentially released Clo from the hydrogel rapidly constricted the peripheral arterial vessels, reducing the blood absorption of Rop and thus enhancing the local Rop accumulation at the injection site. The subsequently sustainable release of Rop from the fiber, significantly prolonged the sciatic nerve block of rats. Remarkably, an amazing sensorimotor segregation effect was achieved, as the sensory blockade (32.0 ± 1.4 h) lasted significantly longer than the motor blockade (20.3 ± 0.9 h). Additionally, the Fiber-Rop/Gel-Clo composite presented good biodegradability and biosafety in vivo. Conclusions: Our designed Fiber-Rop/Gel-Clo composite with minimal invasion, prolonged synergistic analgesia, and strikingly sensorimotor segregation effect, posted a promising prospect for regional long-term walking analgesia in clinical treatment.

Use of Intravenous Paracetamol Preoperatively Favors Lower Risk of Delirium and Functional Recovery in Elderly Patients with Hip Fracture: A Propensity Score-Matched Analysis

We aimed to investigate whether the use of intravenous paracetamol (IVP) preoperatively in intertrochanteric fracture (IF) patients aged 65 years or over receiving intramedullary fixation had significantly benefits on the pain score at discharge, delirium incidence, length of hospital stay (LOS), functional outcomes, and mortality. A retrospective analysis of all surgically treated patients presenting with IF was conducted at a single Level I trauma center in China between Jan. 2016 and Jan. 2020. The data concerning patients' demographics, injury-related data, surgery-related data, operation-related data, in-hospital data, and postoperative outcomes were extracted. To minimize potential confounding and selection bias, the propensity score matching (PSM) method was performed via the caliper matching method by using a 1 : 1 ratio. After PSM, McNemar's chi-square tests were used to examine the association of using IVP with outcome analyses. The Spearman correlations of IVP using, pain scores, and the factors which may influence them were also computed. After screening 2963 consecutive patients, 2166 were included finally, including 1576 in the non-IVP group and 590 in the IVP group. After PSM, 531 remained in each group. The pain scores at discharge were significantly between the two groups before and after matching (all p < 0.001). The differences of delirium rate and functional outcomes became significant after propensity score-based matching (p=0.001 and 0.033, respectively), although they were not significant before matching. No significant difference was observed in other operation-related data, LOS, and crude mortality rates at 30-day, 90-day, and 12-month before and after PSM. In conclusion, this study highlights the need for preoperative IVP use to optimize pain control, postoperative functional recovery, and minimize pain-related comorbidities such as delirium in elderly patients with hip fracture.