Enhanced Postoperative Pain Management and Mobility Following Arthroscopic Knee Surgery: A Comparative Study of Adductor Canal Block with and without IPACK Block

Abstract

Background

Arthroscopic knee surgery (AKS) is minimally invasive, reducing hospital stay compared to traditional surgery, but postoperative pain remains a significant issue. This study compared the analgesic and functional outcomes following AKS following anesthesia using adductor canal block (ACB) with and without anesthesia using the interspace between the popliteal artery and posterior capsule of the knee (IPACK) block under spinal anesthesia (SA).

Material/Methods

We randomly allocated 120 patients into 3 groups: IPACK+ACB+SA for Group A (n=40), ACB+SA for Group B (n=40), and SA for Group C (n=40). The outcome was the visual analog scale (VAS) score evaluated at rest and during activity at 3 h, 6 h, 12 h, 24 h, and 48 h postoperatively, the frequency of administration of postoperative rescue analgesic, and the maximal walking distance at 24 h and 48 h postoperatively.

Results

Compared with Group C, the VAS scores in Group A were significantly lower at 48 h postoperatively (P<0.05). There was a significant difference in the frequency of postoperative rescue analgesia use among the 3 groups (P=0.001). In a subgroup analysis of meniscus shaping under arthroscopy, the resting VAS score in Group A was lower than that in Group B and Group C at 48 h postoperatively (P<0.05). The maximum walking distance of Group A was longer than that of Group B and Group C at 24 h and 48 h postoperatively (P<0.01).

Conclusions

The effect of postoperative analgesia in the group receiving IPACK combined with ACB after AKS was obviously superior. In arthroscopic meniscus repair surgery, the duration of analgesia was longer, and the maximum walking distance at 48 h postoperatively was longer.

Introduction

Arthroscopic knee surgery (AKS), a minimally invasive procedure, is widely used in orthopedic surgery because it minimizes soft-tissue injury and reduces the length of hospital stay in the orthopedics unit compared with traditional open-field surgery [1]. However, postoperative pain is still a serious problem. Surgery is one of the main factors causing postoperative pain, including preoperative tissue damage, intraoperative pneumatic tourniquet use, postoperative inflammatory reaction, and other factors. Moderate to severe pain occurs in almost all patients undergoing knee arthroscopy at 1 h after surgery, and decreased at the end of 24 h. Intra-articular remifentanil can decrease postoperative pain and analgesic requirements in patients [2]. There are many ways to reduce acute pain after arthroscopic knee surgery. Oral or intravenous drugs for analgesia are the most basic way to relieve postoperative pain, but large amounts of postoperative rescue analgesia can increase the incidence of adverse drug reactions such as nausea, vomiting, itching, and gastrointestinal bleeding. Local anesthetics (Las) are commonly infiltrated into surgical wounds for postsurgical analgesia. Local infiltration analgesia is an essential component of multimodal analgesia after AKS [3]. Although local infiltration is effective in analgesia, it is very important to determine if this practice offers any protection against surgical site infections and the increased risk of local anesthetic toxicity [4,5].

Ultrasound-guided regional nerve block is a visualization technique that has the advantages of being a simple procedure and plays an important role in analgesic effects. Sciatic nerve block combined with femoral nerve block is effective when there is inadequate pain relief after AKS, but both can affect lower-limb muscle strength, limiting early recovery of motor function and increasing the risk of falls. It also delays patient recovery surgery [6]. Effective pain control is challenging after knee joint surgery owing to the complex innervation of the knee joint. The adductor canal block (ACB) is a space formed by the fascia envelope and is located in the inner part of the thigh. It mainly contains the saphenous nerve, femoral artery, femoral vein, and lymphatic vessels. The saphenous nerve is the main sensory nerve of the adductor duct, and it is one of the sensory nerve branches of the femoral nerve, which innervates the skin of the anterior, inner, and lower parts of the knee joint and some sensory areas in the joint cavity [7]. ACB can provide adequate pain relief to the anterior knee while sparing motor function of the quadriceps muscles [8,9]. Infiltration between the popliteal artery and capsule of the knee (IPACK) is a block that specifically targets the posterior knee. IPACK has been reported to deliver additional pain relief when administered along with other standard procedures, indicating the possible superiority of distal injection at the level of the femoral condyles for management of posterior knee pain [10,11].

A meta-analysis showed that adding IPACK to ACB reduced pain scores 24 h after TKA and improved functional recovery in patients compared with ACB alone [10], but there was no reduction in opioid analgesic consumption. However, different studies have shown that compared with ACB alone, IPACK can significantly reduce the postoperative pain score and the use of analgesics after TKA, but it does not significantly improve postoperative mobility [11]. TKA surgery creates serious trauma in the knee area caused by bone resection, soft-tissue release, prosthesis implantation, and wound suturing [12]. The lack of mobility improvement may be related to TKA trauma. For arthroscopic knee surgery, including meniscus dressing and molding, popliteal cyst resection, and simple cruciate ligament reconstruction surgery, the trauma is much less than with TKA. Because TKA causes less trauma than AKS, we hypothesized that compared with ACB alone, the addition of IPACK can significantly reduce the pain score and the use of analgesics after AKS, and that postoperative motor function can be significantly improved.

The purpose of this study was to analyze the effects of IPACK and ACB block on analgesia and functional recovery after AKS compared with ACB alone in patients undergoing different types of elective AKS. We hypothesized that IPACK combined with ACB would reduce the frequency of postoperative rescue analgesia and increase the maximum walking distance. We believe that this study will further validate the efficacy of IPACK combined with ACB in different types of elective AKS.

Material and Methods

This randomized controlled trial was conducted at Longgang District Central Hospital of Shenzhen, Shenzhen, Guangdong, China. We performed a clinical trial in adult patients scheduled for elective AKS under single spinal anesthesia (SA). It was approved by the Medical Ethics Committee of Longgang District Central Hospital of Shenzhen (date: 29/12/2020; number: 2020ECPJ028). Informed consent was obtained from all patients participating in the trial. The protocol was registered in the Chinese Clinical Trials Registry and was approved. (date: 11/12/2022; number: ChiCTR2200066597). This study was reported in accordance with CONSORT guidelines.

Randomization and Blinding

This study was a randomized controlled trial evaluating the postoperative analgesic effects of 3 different anesthesia methods. The primary outcome measure was the visual analog scale (VAS) score. Based on preliminary experiments, the mean 24-h VAS scores for the 3 groups were 1.4, 2.2, and 2.4, with standard deviations of 0.98, 0.96, and 1.20, respectively. In accordance with the requirements of a bilateral test, setting α at 0.05 and power at 90% (1-β), PASS 15.0.5 software was used to calculate the required sample size of n=34 cases per group. Considering a potential loss or refusal rate of 10%, the software suggested a minimum of 37.4 cases per group. Therefore, this study ultimately included 40 samples per group, totaling 120 cases [13,14].

$$\text{n}={\varphi }^2(\mathrm{\Sigma }{s}_i^2/\text{g})/[\mathrm{\Sigma }{({\overline{X}}_1-\overline{X})}^2/(\text{g}-1)]$$

n represents the sample size per group and g represents the number of groups;

s_i and X stand for standard deviation and mean, respectively; ϕ values can be obtained by looking up α, β, v1, v2 table.

Patients were randomly allocated into 3 groups of 40 patients each. Randomization was performed using a computer-generated randomization sequence concealed in sealed opaque envelopes that were opened by trained research personnel on the day of surgery. Patients were randomized in a 1: 1: 1 ratio into Group A (patients received IPACK+ACB+SA), Group B (patients received ACB+SA), and Group C (patients received SA). The envelope was opened by an anesthesiologist who was not involved in the design of the study. The researchers who collected the data (Investigator A) and performed the statistical analysis (Investigator B) remained blinded to the trial grouping of patients throughout the study.

Participants

A total of 120 patients ages 18–65 years with a physical status grade according to the American Society of Anaesthesiologists classification (ASA) of 1–3 undergoing unilateral AKS under SA were enrolled in this randomized controlled study. The study was conducted between April 2020 and March 2021. The exclusion criteria were body mass index (BMI) more than 40 kg/m², chronic kidney disease or cardiac insufficiency, chronic use of analgesics (daily use at least 60 mg morphine equivalents for >4 weeks) or psychotropics, allergy to ropivacaine, preexisting lower-extremity neurological deficit, inability to comprehend or cooperate, patient refusal of either spinal anesthesia or regional block, and failure of the IPACK or ACB procedure prior to single SA.

Adductor Canal Block Technique [15]

ACB was performed with the patient supine. The patient was prepped in a sterile manner, and a linear transducer (GE Logiq V2, 10 to 12 MHz) was placed on the mid-thigh. The femur was visualized, and the transducer was moved medially until the superficial femoral artery, deep to the sartorius muscle, was visualized in the adductor canal. Below the sartorius muscle, the femoral artery was identified. The saphenous nerve is adjacent to the femoral artery. A 15° 0.71×80 mm, 22-G nerve block needle (Stimuplex D, B Braun) was inserted parallel to the long axis of the transducer from the lateral side. Normal saline with a volume of 1~2 mL was injected into the suspected adductor canal to confirm that the needle was placed in the correct position. Twenty mL of 0.25% ropivacaine was administered around the saphenous nerve in 5-mL increments after careful aspiration (Figure 1).

Figure 1.

Ultrasound images demonstrating ACB; F – distal left lower limb; N – proximal left lower limb; I – inner thigh; SM – sartorius; A – femoral artery; V – venae femoris; arrows indicate the needle; anesthetic stands for injection target; – puncture needle into needle position; – ultrasonic probe placement position.

IPACK Block Technique [16]

The IPACK block was performed with the patient supine, the knee elevated, and the hip slightly abducted and externally rotated to gain access to the medial surface of the distal thigh. A curvilinear transducer (GE Logiq V2, 10 to 12 MHz) was positioned on the medial thigh 1–2 fingerbreadths above the patella. The femur was identified along with the femoral shaft, popliteal artery, and posterior space of the femoral shaft. A 15° 0.71×80 mm, 22-G nerve block needle (Stimuplex D, B Braun) was then advanced in-plane to the transducer towards the posterior space between the femur and the popliteal artery. Twenty mL of 0.25% ropivacaine was injected in 5-mL increments with careful aspirations (Figure 2).

Figure 2.

Ultrasound images demonstrating IPACK. SN – sciatic nerve; A – popliteal artery; V – popliteal vein; arrows indicate the needle; F – distal left lower limb; N – proximal left lower limb; I – inner thigh; SM – sartorius; A – popliteal artery; V – popliteal venae; arrows indicate the needle; anesthetic stands for injection target; – puncture needle into needle position; – ultrasonic probe placement position.

Perioperative Management

Adequate preoperative fasting was confirmed on the day of surgery. The patient was instructed to eat no solid food for ≥8 h and drink no fluids for ≥4 h preoperatively. Upon arrival to the operating theater, routine monitoring was performed continuously, including electrocardiography, noninvasive blood pressure readings, and pulse oximetry. Systolic blood pressure (SBP), heart rate (HR), and pulse oximetry were assessed every 5 min. The veins were cannulated with an 18-gauge venous cannula on the contralateral upper limb, and an infusion was started with lactated Ringer’s solution at a rate of 6–8 mL/kg/h. Oxygen was administered with a face mask (3–4 L/min). The study intervention was performed after opening the peripheral vein.

Ultrasound-guided IPACK and ACB were performed in Group A, and ACB was performed in Group B. The VAS was evaluated at 5–10 min after IPACK and/or ACB, including the posterior area of the knee (IPACK area) and the anterior, medial, and inferior area of the knee (ACB area). When patients in Group A and Group B developed sensory block, SA was administered using 15 mg 0.5% hyperbaric ropivacaine in the lateral decubitus position at the L3–L4 intervertebral space (patients in Group C only received lumbar anesthesia). The level of sensory block in SA was controlled between T8 and T10 by adjusting the body position, injection speed, and injection time. All of the above intraoperative procedures were performed by the same anesthesiologist, who was blinded to the study. All AKS procedures were performed by the same surgeon using a standard approach with a tourniquet. All patients received standardized postoperative analgesia using intravenous flurbiprofen (1.0 mg/kg) every 12 h and IV injection of pentazocine at a dose of 30 mg as rescue analgesia if the VAS score was more than 4 points, which was repeated if necessary. After hospital discharge, the patients who felt pain and requested an analgesic were instructed to take 200 mg oral celecoxib tablets once daily.

Outcome Measurement

The outcomes were pain scores measured by the VAS 0–10 (0 cm no pain and 10 cm worst pain) at rest and during activity (joint flexion more than 45°). VAS scores were recorded at 3 h, 6 h, 12 h, 24 h, and 48 h postoperatively, at discharge and at 1 week after hospital discharge. The outcomes were the frequency of administration of postoperative rescue analgesics, doses of oral celecoxib taken at 1 week after discharge, maximum walking distance at 24 h and 48 h postoperatively, and incidence of postoperative complications (eg, postoperative nausea and vomiting, puncture site infection, puncture site haematoma, urinary retention, nerve injury and foot drop).

In this study, 2 sets of records were established:

Record table 1: Researcher A was responsible for training patients to document their VAS scores at various time points following surgery. VAS scores were recorded at 3 h, 6 h, 12 h, 24 h, and 48 h postoperatively; as well as upon discharge and 1 week after hospital discharge. With the assistance of nurses, patients documented their maximum walking distance at 24 and 48 h after surgery. A standardized scale was placed at the entrance of each ward to ensure accurate recording by patients. The completed form was collected by Researcher A, who remained blinded to the specific trial groups throughout the study.

Table 1.

Comparison of basic data between the 3 groups (%).

Project	Group A (n=40)	Group B (n=40)	Group C (n=40)	F/χ2	P value
Age (years)a (mean±SD)	40.7±12.6	42.3±11.1	40.5±12.2	0.279	0.757
Gender(M/F)b	24/16	8/22	19/21	2.067	0.356
BMI (kg/m2)a (mean±SD)	23.6±2.6	23.5±2.2	23.6±2.3	0.069	0.933
ASA classification I/II (n)b	13/27	10/30	11/29	0.575	0.750
Type of surgery (arthroscope)				0.304	0.990
Meniscal trimming moldingb	20 (50.0)	21 (52.5)	21 (52.5)
Meniscal repair molding+popliteal cyst resectionb	11 (27.5)	9 (22.5)	10 (25)
Cruciate ligament reconstruction surgeryb	9 (22.5)	1 0(25)	9 (22.5)
Operative time (min)a (mean±SD)	51.9±22.8	53.0±21.0	51.0±23.6	0.083	0.920
Preoperative VAS pain score
At resta (mean±SD)	1.4±0.9	1.6±0.9	1.4±0.8	0.494	0.611
At activitya (mean±SD)	2.0±0.8	2.2±0.8	2.2±0.8	0.449	0.639

BMI – body mass index; VAS – visual analog scale; ASA – American Society of Anaesthesiologists classification;

^asingle-factor ANOVA test;

^bχ² tests. Group A – IPACK+ACB+SA (IPACK and ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group B – ACB+SA (ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group C – SA (nerve block is not selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia).

Record table 2: Researcher A reviewed the physician’s order system and nursing record sheets, noting the patient’s postoperative ward analgesia requirements and any incidence of postoperative complications, respectively. Researcher A compiled all trial data, which were subsequently analyzed by Researcher B, who remained blinded to the specific trial groups throughout the study.

Table 2.

Postoperative VAS pain scores at rest and during activity in the 3 groups (mean±SD).

Project	Group A (n=40)	Group B (n=40)	Group C (n=40)	F	P value
Postoperative VAS score at rest
3 h	0.00±0.00	0.00±0.00	0.00±0.00	–	–
6 h	0.25±0.49#*	0.73±0.78#	1.65±0.86	37.909	0.000
12 h	0.75±0.87#*	1.95±0.90#	2.60±1.10	37.819	0.000
24 h	1.70±1.20#	2.18±1.08	2.55±0.99	6.063	0.003
48 h	1.38±1.08#	1.68±1.02	2.10±0.96	5.101	0.008
Discharge	0.30±0.56	0.33±0.52	0.48±0.60	1.129	0.327
1 week after discharge	0.25±0.44	0.28±0.51	0.23±0.42	0.120	0.887
Postoperative VAS score at activity
3 h	0.00±0.00	0.00±0.00	0.00±0.00	–	–
6 h	0.60±0.87#*	1.45±0.90#	2.35±0.77	42.365	0.000
12 h	1.03±0.95#*	2.45±0.93#	3.50±1.01	66.331	0.000
24 h	1.98±1.14#	2.43±0.98	2.88±0.94	7.697	0.001
48 h	1.53±1.11v	1.75±1.06	2.13±1.11	3.075	0.050
Discharge	0.70±0.82	0.65±0.66	1.00±0.68	2.727	0.070
1 week after discharge	0.43±0.55	0.50±0.60	0.50±0.60	0.221	0.802

^#indicates comparison with Group C, P<0.05;

^*indicates P<0.05 for comparison with Group B, which was statistically significant;

VAS – Visual Analog Scale. The P value is the comparison between groups. The VAS score at rest and activity 3 h after surgery was “0”. Group A – IPACK+ACB+SA (IPACK and ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group B – ACB+SA (ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group C – SA (nerve block is not selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia).

Statistical Analysis

We used SPSS version 25.0 software (SPSS, Inc., Chicago, IL, USA) for statistical analysis. Continuous variables are presented as the mean±standard deviation or median (interquartile ranges). Categorical variables are represented as percentages. One-way analysis of variance with post hoc Bonferroni correction was used for normally distributed continuous variables, and the Kruskal-Wallis analysis with post hoc Nemenyi test was used for skewed continuous variables. Chi-square or Fisher’s tests were applied for categorical variables. Subgroup analysis was performed for different surgical methods. A P value of <0.05 signifies significant differences among the 3 groups.

Results

We included 120, who were randomized into Group A, Group B, and Group C, with 40 patients in each group. All patients completed the study and their data were analyzed (Figure 3).

Figure 3.

CONSORT diagram of patient flow through the study. ACB – adductor canal block; IPACK – Interspace between popliteal artery and posterior capsule of the knee; SA – apinal anesthesia; Group A – IPACK+ACB+SA (IPACK and ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group B – ACB+SA (ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group C – SA (nerve block is not selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia).

Comparison of Basic Characteristics of Patients in the 3 Groups

There were no significant differences in the baseline characteristics in the 3 groups – age, sex, type of surgery, duration of surgery, operative time, ASA classification, body mass index (BMI) and VAS score at rest and during activity at 24 h preoperatively (P>0.05) (Table 1).

Comparison of Postoperative VAS Scores Among the 3 Groups

The VAS scores at rest and during activity at 6 h, 12 h, 24 h, and 48 h postoperatively were highest in C Group and lowest in A Group (P<0.05). Resting and active VAS scores at discharge and 1 week after discharge were similar among the 3 groups (P>0.05). Table 2 shows the statistical significance of the differences among the 3 groups (Table 2).

Comparison of Postoperative Analgesic Consumption Among the 3 Groups

The lowest frequency of postoperative rescue analgesia was recorded in Group A and the highest in Group C (P=0.001). There was no significant difference in the dose of postoperative oral analgesics among the 3 groups at 1 week after hospital discharge (P>0.05) (Table 3).

Table 3.

Frequency of postoperative rescue analgesia and the dose oral analgesics administered at 1-week after discharge in the 3 groups (mean±SD).

Parameter	Group A (n=40)	Group B (n=40)	Group C (n=40)	F	P value
Frequency of postoperative rescue analgesia	0.18±0.39#	0.50±0.75	0.78±0.89	7.186	0.001
Analgesic agent at 1-week post-discharge (granules)	2.30±2.27	2.98±2.15	2.85±2.36	1.008	0.368

^#indicates comparison with Group C, P<0.05;

^*indicates P<0.05 for comparison with Group B, which was statistically significant.

The P value is the comparison between groups. Group A – IPACK+ACB+SA (IPACK and ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group B – ACB+SA (ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group C – SA (nerve block is not selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia).

Comparison of Postoperative Maximum Walking Distance Among 3 Groups

The maximum walking distance 24 h and 48 h postoperatively was longer in Group A than in the other 2 groups. Table 4 presents the statistical significance of the differences among the 3 groups (P<0.05) (Table 4).

Table 4.

Maximum postoperative distance in the 3 groups (mean±SD).

Parameter	Group A (n=40)	Group B (n=40)	Group C (n=40)	F	P value
Postoperative 24 h (m)	26.3±14.30#*	19.4±10.94	15.31±9.49	8.926	0.000
Postoperative 48 h (m)	73.4±35.25#*	53.0±27.25	43.3±23.51	11.188	0.000

^#indicates comparison with Group C, P<0.05;

^*indicates P<0.05 for comparison with Group B, which was statistically significant.

Group A – IPACK+ACB+SA (IPACK and ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group B – ACB+SA (ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group C – SA (nerve block is not selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia).

Comparison of the Incidences of Postoperative Adverse Reactions Among the 3 Groups

The incidence of nausea and vomiting in Group A was significantly lower than in Group C (P<0.05). There was no significant difference in the incidence of postoperative urinary retention, puncture site infection, puncture site haematoma, nerve injury, or foot drop among the 3 groups (P>0.05) (Table 5).

Table 5.

The incidence of postoperative complications in 3 groups (%).

Project	Group A (n=40)	Group B (n=40)	Group C (n=40)	χ2	P value
Nausea	1 (2.5)	4 (10.0)	9 (22.5)	7.314	0.007
Vomit	1 (2.5)	3 (7.5)	8 (20.0)	6.135	0.014
Retention of urine	1 (2.5)	2 (5.0)	2 (5.0)	0.417	0.812
Puncture site infection	0 (0.0)	0 (0.0)	0 (0.0)	–	–
Puncture site hematoma	0 (0.0)	0 (0.0)	0 (0.0)	–	–
Nerve damage	0 (0.0)	0 (0.0)	0 (0.0)	–	–
Foot drop	1 (2.5)	0 (0.0)	0 (0.0)	1.834	1.000

Group A – IPACK+ACB+SA (IPACK and ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group B – ACB+SA (ACB were selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia); Group C – SA (nerve block is not selected as postoperative analgesia in arthroscopic knee surgery under single lumbar anesthesia).

Subgroup Analysis and Comparison

A subgroup analysis was performed for the 3 types of surgery, including knee arthroscopic meniscus repair (Type 1 Group), meniscus repair+popliteal cyst resection (Type 2 Group), and arthroscopic cruciate ligament reconstruction (Type 3 Group). During knee arthroscopic meniscus repair surgery (Type 1 Group), the VAS scores during activity at 6 h, 12 h, 24 h, and 48 h postoperatively were the highest in the C1 Group, and the lowest in the A1 Group (P<0.05), while the VAS scores during activity at 6 h, 12 h, and 24 h postoperatively were highest in the C1 Group and lowest in the A1 Group (P<0.05). The same change was observed in the Type 2 Group (P<0.05). During arthroscopic cruciate ligament reconstruction of the knee joint (in the Type 3 Group), the VAS score at rest and during activity at 6 h and 12 h postoperatively was the highest in the C3 Group and the lowest in the A3 Group (P<0.05) (Table 6). The frequency of administration of postoperative rescue analgesia was significantly lower in Group A than in the other 2 groups (P<0.05). The maximum walking distance in Group A1 at 24 h and 48 h postoperatively was longer than in Group B1 and Group C1 in the Type 1 Group (P <0.05), and there was no significant difference in the maximum walking distance at 24 h and 48 h postoperatively in the Type 2 group and Type 3 Group (P>0.05). Postoperative vomiting in Group A2 in the Type 2 Group was significantly lower than in Group B2 and Group C2 (P>0.05) (Table 7).

Table 6.

Subgroup analysis of postoperative VAS scores after different types of surgery (mean±SD).

	Type 1 Group		P 1	Type 2 Group		P 2	Type 3 Group		P 3
Postoperative VAS score at rest
6 h	A1	0.3±0.571	0.00*	A2	0.18±0.405	0.002*	A3	0.22±0.441	0.00*
	B1	0.48±0.602		B2	0.33±0.707		B3	1.6±0.516
	C1	1.43±0.87		C2	1.7±1.059		C3	2.11±0.333
12 h	A1	0.65±0.813	0.00*	A2	0.73±0.905	0.00*	A3	1.0±1.0	0.00*
	B1	1.48±0.873		B2	2.22±0.667		B3	2.7±0.483
	C1	2.14±0.964		C2	2.8±1.033		C3	3.44±1.014
24 h	A1	1.0±1.026	0.005*	A2	1.82±0.603	0.006*	A3	3.11±0.782	0.648
	B1	1.52±0.928		B2	2.56±0.527		B3	3.2±0.789
	C1	2.05±0.921		C2	2.8±0.789		C3	3.44±0.527
48 h	A1	0.8±0.834	0.012*	A2	1.36±0.809	0.012*	A3	2.67±0.707	0.689
	B1	1.0±0.837		B2	2.11±0.333		B3	2.7±0.675
	C1	1.67±0.966		C2	2.3±0.675		C3	2.89±0.601
Postoperative VAS score at activity
6 h	A1	0.6±0.955	0.00*	A2	0.91±0.831	0.004*	A3	0.22±0.441	0.00*
	B1	1.19±0.873		B2	1.33±0.866		B3	2.1±0.738
	C1	2.19±0.814		C2	2.4±0.843		C3	2.67±0.5
12 h	A1	0.85±0.993	0.00*	A2	0.91±0.944	0.00*	A3	1.56±0.882	0.00*
	B1	1.95±0.669		B2	2.78±1.093		B3	3.2±0.632
	C1	3.14±0.854		C2	3.8±0.919		C3	4±1.225
24 h	A1	1.3±1.129	0.001*	A2	2.18±0.405	0.024*	A3	3.22±0.441	0.397
	B1	1.81±0.75		B2	2.89±0.782		B3	3.3±0.675
	C1	2.48±0.873		C2	3.1±0.994		C3	3.56±0.527
48 h	A1	0.9±0.852	0.105	A2	1.55±0.82	0.067	A3	2.89±0.601	0.797
	B1	1.19±0.981		B2	1.89±0.61		B3	2.8±0.632
	C1	1.57±1.028		C2	2.5±0.972		C3	3±0.707

^*indicates P<0.05, which was statistically significant.

VAS – visual analog scale; Type 1 Group – meniscal trimming molding Group; Type 2 Group – meniscal repair molding+popliteal cyst resection Group; type 3 Group – cruciate ligament reconstruction surgery Group. A1, B1, and C1 represent the subgroup analysis of Groups A, B, and C, respectively, in arthroscopic meniscus repair. A2, B2, and C2 represent the subgroup analysis of Group A, B, and C, respectively, in arthroscopic meniscal repair molding+popliteal cyst resection. A3, B3, and C3 represent the subgroup analysis of Groups A, B, and C, respectively, in arthroscopic cruciate ligament reconstruction surgery.

Table 7.

Subgroup analysis of different indicators after different types of surgery (mean±SD).

	Type 1 Group		P 1	Type 2 Group		P 2	Type 3 Group		P 3
Frequency of postoperative rescue analgesia	A1	0.05±0.224	0.007*	A2	0.00±0.0	0.012*	A3	0.67±0.5	0.002*
	B1	0.1±0.301		B2	0.33±0.5		B3	1.5±0.71
	C1	0.29±0.463		C2	0.7±0.68		C3	2.0±0.71
Postoperative maximum walking distance (m)
24 h	A1	25.73±12.32	0.021*	A2	20.55±15.0	0.739	A3	25.56±11.65	0.337
	B1	18.81±14.07		B2	19.90±14.77		B3	20.8±12.17
	C1	16.48±10.22		C2	17.55±10.39		C3	18.67±11.21
48 h	A1	70.55±31.68	0.023*	A2	58.55±39.81	0.749	A3	67.67±30.73	0.372
	B1	54.14±33.98		B2	54.67±37.95		B3	58.4±30.78
	C1	46.05±24.46		C2	48.7±26.16		C3	51.44±26.72
Postoperative complications (nausea)	A1	1 (5.0)	0.534	A2	0 (0.0)	0.063	A3	0 (0.0)	0.231
	B1	0 (0.0)		B2	2 (22.02)		B3	2 (20.0)
	C1	2 (9.5)		C2	4 (40.0)		C3	3 (33.3)
Postoperative complications (vomiting)	A1	1 (5.0)	0.323	A2	0 (0.0)	0.01*	A3	0 (0.0)	0.231
	B1	0 (0.0)		B2	1 (11.1)		B3	2 (20.0)
	C1	0 (0.0)		C2	5 (50.0)		C3	3 (33.3)

^*indicates P<0.05, which is statistically significant.

Type 1 Group – meniscal trimming molding Group; Type 2 Group – meniscal repair molding+popliteal cyst resection Group; Type 3 Group – cruciate ligament reconstruction surgery Group, A1, B1, and C1 represent the subgroup analysis of Groups A, B, and C, respectively, in arthroscopic meniscus repair; A2, B2, and C2 represent the subgroup analysis of Groups A, B, and C, respectively, in arthroscopic meniscal repair molding + popliteal cyst resection; A3, B3, and C3 represent the subgroup analysis of Groups A, B, and C, respectively, in arthroscopic cruciate ligament reconstruction surgery.

Discussion

In our study, we observed the effect of IPACK combined with ACB on postoperative analgesia and rehabilitation in patients undergoing AKS in SA. We found that IPACK combined with ACB and SA decreased the VAS score at rest and activity 6 h and 12 h postoperatively compared with ACB and SA technique and decreased the VAS score at rest and activity 6 h, 12 h, 24 h and 48 h postoperatively compared with SA. IPACK combined with ACB and SA was compared with SA, the VAS score was significantly lower, the maximum walking distance was longer, and the frequency of postoperative rescue analgesia administered postoperatively was lower at 48 h postoperatively, suggesting that IPACK combined with ACB can improve the pain score at 48 h postoperatively and that rehabilitation time could be reduced. The above results differed slightly from the results of the study on IPACK combined with ACB after TKA. In that study, the addition of IPACK to ACB reduced the 48 h VAS score after AKS, and the analgesia time after AKS in that study was longer than that after TKA in previous studies [10,11].

As ultrasound-guided local anesthetic infiltration of the interspace between the popliteal artery and capsule of the posterior knee, IPACK demonstrated dye spread throughout the popliteal fossa, without proximal sciatic nerve involvement, staining the articular branches that supply the posterior capsule [17]. IPACK has shown efficacy for posterior knee pain. The addition of IPACK to ACB in a multimodal pain management protocol can effectively reduce consumption of opioids in the early postoperative period [18]. IPACK and ACB combined relieved pain during movement better than IPACK block alone during the 8 h postoperatively after TKA in the setting of multimodal analgesia [19].

The literature has shown that the IPACK and ACB techniques do not affect quadriceps strength [18]. Appropriate analgesia is also an important condition for promoting early postoperative rehabilitation. IPACK combined with ACB has been shown to be beneficial for postoperative analgesia, reduction of morphine consumption, and early functional recovery after TKA [10–23]. In this study, IPACK combined with ACB in multimodal analgesia after AKS reduced analgesic use and it increased the maximum walking distance at 24 h and 48 h postoperatively. Therefore, IPACK combined with ACB can promote rehabilitation after AKS. The incidence of postoperative nausea and vomiting in Group A was lower than that in the other 2 groups, and the incidence of postoperative vomiting was lower because of the lower analgesic use.

The IPACK block technique can reduce posterior knee pain after AKS. The effectiveness of the IPACK block particularly depends on needle position and orientation. A previous study established a safe and effective location for a radiofrequency ablation-based IPACK block, with the needle tip positioned either lateral to the tibial artery or in the space between the posterior knee capsule and the tibial artery [24]. In the present study, foot drop in Group A was resolved by postoperative day 1 in 1 patient. A small number of patients present with peroneal nerve palsy when IPACK block and ACB are performed, perhaps because the common peroneal nerve was blocked when the IPACK block and ACB were performed [25]. The foot drop was caused by the spread of the local anesthetic. Anatomical variations should also be considered, as foot drop can be caused by distal spread of local anesthetic towards the terminal branches of the sciatic nerve after the IPACK block or a combination of the IPACK block and ACB [26]. Local anesthetic in the distal part of the adductor canal could spread to the popliteal fossa in a small minority of cases and adductor canal block techniques are unlikely to block the sciatic nerve and its main branches [27]. In a neonatal cadaveric study, methylene blue dye (0.3 ml/kg) was injected proximally and distally. Proximal injections resulted in staining of some of the articular branches, while the distal injections resulted in staining of all 4 articular branches [28]. Therefore, when IPACK and ACB are performed together, care is needed to avoid diffusion of the liquid to the common peroneal nerve, resulting in foot drop. The choice of puncture point is also very important, and proximal injection can be used for ACB.

The combination of continuous ACB and distal iPACK block can decrease the incidence of moderate to severe posterior knee pain, improve postoperative pain over the first 24 h after total knee arthroplasty, and promote recovery of motor function, but the opioids consumption was not decreased by adding distal IPACK to continuous ACB [29]. In our study, IPACK combined with ACB provided adequate analgesia and significantly decreased the frequency of postoperative rescue analgesia. IPACK combined with ACB can improve the postoperative pain score over the first 48 h. Studies have also confirmed that IPACK combined with ACB was the most efficacious option for improving ambulation ability and shortening the length of hospital stay. It significantly reduces pain and opioid consumption at 48 h. However, IPACK combined with ACB is not the recommended technique for short-term (24 h) pain control [30,31].

In our study, importantly, a subgroup analysis was performed for the 3 types of surgery, including the Type 1 Group (meniscal trimming molding), Type 2 Group (meniscal repair molding + popliteal cyst resection), and Type 3 Group (cruciate ligament reconstruction surgery). During meniscus trimming molding surgery, the VAS score of Group A1 in resting state was significantly lower than that of Group B1 and Group C1 within 48 h, and the same change was observed in the Type 2 Group. During cruciate ligament reconstruction surgery, the resting VAS score in Group A3 was significantly lower than that in Group B3 and Group C3 within 12 h. The maximum walking distance in Group A1 was longer than in Group B1 and Group C1 in the meniscus trimming molding surgery. There was no significant difference in the rate of postoperative complications among the 3 groups. The results showed that IPACK combined with ACB was more suitable for meniscus trimming molding surgery, and its postoperative analgesia lasted approximately 48 h after surgery. The reason may be minor trauma in meniscus trimming molding surgery. According to the degree of tissue damage in the 3 types of surgery, trauma in meniscus trimming molding surgery was relatively minor, and IPACK combined with ACB maintained longer postoperative analgesia in meniscus trimming molding surgery. Some studies have shown that IPACK combined with ACB can be used for analgesia after TKA, and the pain score is statistically significant, but the additional analgesic benefits are doubtful. Knee arthroscopic meniscus trimming molding surgery is less invasive than TKA surgery. It can be seen from the subgroup analysis of the present study that IPACK combined with ACB may be more suitable for surgery in the knee area, with relatively less trauma.

Strengths and Limitations

The innovations of this study are as follows: (1) Most current studies on IPACK and ACB focused on postoperative analgesia and functional recovery after TKA surgery, and rarely studied AKS. AKS is similar to TKA surgery, but the surgical trauma is less than in TKA, so the study of IPACK and ACB is very significant for clinical diagnosis and treatment. (2) Through subgroup analysis, we analyzed the effects of IPACK combined with ACB on postoperative analgesia and rehabilitation of different types of AKS, and found that the effect of knee arthroscopic meniscus dressing and molding surgery was significantly better, which is conducive to guiding clinicians to selectively apply IPACK and ACB analgesia methods.

The present study has certain limitations. It had a small sample size and was a single-center study, so larger studies are needed to produce more generalizable results. The type of AKS was not significantly different among the 3 groups, and meniscus repair was the main type of AKS in the 3 groups. The size of the cruciate ligament reconstruction group was small (22–25% of the total sample size). Finally, the precision with which ultrasound-guided IPACK and ACB are performed affects drug diffusion, and the duration of a single-injection nerve block was limited.

Conclusions

The effect of postoperative analgesia in IPACK combined with ACB after AKS was obviously improved. In arthroscopic meniscus repair surgery, the duration of analgesia was longer, and the maximum walking distance at 48 h after surgery was longer.