Efficacy of regional anesthesia in hip preservation surgeries: a systematic review

ABSTRACT The purpose of this study was to review the current literature on perioperative pain management in hip arthroscopy, periacetabular osteotomy and surgical hip dislocation. A systematic review of the literature published from January 2000 to December 2022 was performed. Selection criteria included published randomized controlled trials, prospective reviews and retrospective reviews of all human subjects undergoing hip preservation surgery. Exclusion criteria included case reports, animal studies and studies not reporting perioperative pain control protocols. Thirty-four studies included hip arthroscopy in which peripheral nerve blocks were associated with a significant reduction in pain score (P = 0.037) compared with general anesthesia alone. However, no pain control modality was associated with a significant difference in postanesthesia care unit opioid use (P = 0.127) or length of stay (P = 0.251) compared with general anesthesia alone. Falls were the most common complication reported, accounting for 37% of all complications. Five studies included periacetabular osteotomy and surgical hip dislocation in which peripheral nerve blocks were associated with an 18% reduction in pain on postoperative Day 2, a 48% reduction in cumulative opioid use on postoperative Day 2 and a 40% reduction in hospital stay. Due to the low sample size of the periacetabular osteotomy and surgical hip dislocation studies, we were unable to determine the significant difference between the means. Due to significant between-study heterogeneity, additional studies with congruent outcome measures need to be conducted to determine the efficacy of regional anesthesia in hip arthroscopy, periacetabular osteotomy and surgical hip dislocation.


IN TRODUCTION
Hip preservation surgeries have grown in popularity over the past decade in treating various pre-arthritic hip conditions in adolescents and adults [1,2].Hip preservation procedures include hip arthroscopy, periacetabular osteotomy (PAO), proximal femoral osteotomy, cartilage restoration and surgical hip dislocation (SHD) [2,3].These procedures aim to improve mechanical function in certain pathologies, including femoroacetabular impingement, labral tears, chondral lesions of the acetabulum and acetabular dysplasia [1,4,5].With new developments in hip preservation surgery, anesthetic techniques must keep pace with surgical advancements.
Regional anesthesia, which includes peripheral nerve blocks (PNBs), local infiltrative anesthesia (LIA) and combined spinal epidural anesthesia, can be helpful in managing moderate-tosevere postoperative pain in patients undergoing hip preservation surgery [6][7][8].Adjunct medications such as non-steroidal anti-inflammatory drugs (NSAIDs) and opioid-based medications are also common pain interventions used to supplement general anesthesia (GA) in hip preservation surgeries.This multimodal approach to pain relief has reduced pain and postanesthesia care unit (PACU) length of stay (LOS) in hip fracture and hip arthroscopy studies [8][9][10][11].Previous studies have also suggested that a multimodal pain regimen can reduce postoperative opioid use, which has become increasingly important in the current opioid crisis [8,[12][13][14].However, there is limited literature directly comparing the efficacy of PNB, LIA and adjunct medication along with GA in hip preservation surgery [8][9][10][11].
This study aims to provide an updated comprehensive systematic review of perioperative pain management in hip arthroscopy as well as a new perspective on anesthetic regimens in PAO and SHD.Part I of this systematic review investigates perioperative pain management in hip arthroscopy.Part II investigates perioperative pain management in PAO and SHD.

M ETHODS Inclusion criteria
Types of studies The literature search performed in this review was limited to original published reports concerning perioperative anesthesia in patients undergoing hip arthroscopy, PAO and SHD.The data analysis did not include abstracts from scientific meetings, unpublished reports, case reports and review articles.

Types of participants
Male and female humans of all ages undergoing hip arthroscopy, PAO or SHD were included in this study.

Types of intervention
Interventions included regional anesthesia, adjunct medication and GA to treat perioperative pain in patients undergoing hip arthroscopy, PAO and SHD.

Types of outcome measures
Pain measurements, reported as visual analog scale (VAS), numerical rating scale (NRS) or Defense and Veterans Pain Rating Scale (DVPRS), were primary outcomes for both the hip arthroscopy and PAO/SHD sections.Opioid consumption [morphine milligram equivalent (MME)] and PACU LOS were secondary outcomes for hip arthroscopy and PAO/SHD.Complications of each block were included.

Quality assessment of included studies
The quality and risk of bias of randomized controlled trials (RCTs) were assessed using the Jadad scale [15].The quality and risk of bias of retrospective review articles were assessed using the methodological index for non-randomized studies (MINORS) criteria [16].

Search strategy
A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines [17].

Statistical analysis
Due to significant heterogeneity between studies, studies were manually grouped by similar outcome measures.Two-sample t-tests and analysis of variances (ANOVA) were used to calculate the significant difference between means, which was set at alpha = 0.05.Due to the low sample size of PAO/SHD anesthetic studies, the P-value was not calculated in this section.

PA RT I: A RTHROSCOP Y Part I: results
This comprehensive literature search for articles related to pain management in arthroscopic hip preservation surgeries initially identified 928 papers, of which 44 were included for abstract and full-text analysis.After exclusions, 34 studies comprised the final analysis (Fig. 1).The details of these studies are outlined in Table I.
PNBs were associated with a significant reduction in pain score (P = 0.037) compared with GA alone.However, no pain control modality was associated with a significant difference in opioid use (P = 0.127) or LOS (P = 0.251) compared with GA alone, as depicted in Fig. 2. A comparison of each block category with a level of significance is analyzed in Table III.

Part I: discussion
The present review analyzes the various pain management strategies in hip preservation surgeries, distinguishing between those used in hip arthroscopy and those used in open PAO or SHD.In hip arthroscopy, there was a significant difference in VAS pain score at discharge with PNB compared with GA alone, but there was no significant difference in opioid usage or LOS among patients receiving FNB, FICB, LPB, QLB, GA, neuraxial anesthesia, NSAIDs or LIA.No single technique provided superior relief compared with other blocks or GA alone.Falls and peripheral neuritis were the most common complications and were most frequently associated with FNB in hip arthroscopy.
PNBs have increased in popularity along with advances in hip preservation surgery.In light of the current opioid epidemic, reducing postoperative opioid use remains an essential goal for enhancing surgical recovery and preventing future abuse.A prior study found that increased opioid dosing in the early postoperative period following total joint arthroplasty was associated with an increased risk for abuse [51].Several individual studies in this review reported superior pain control and reduction in opioid use with regional anesthesia compared with GA alone [19,29,34,35,[43][44][45][48][49][50].When analyzing the outcome measures of all included studies, our manually grouped data suggest that PNB with GA significantly reduces VAS pain scores  compared with GA alone (P = 0.037).However, no other type of anesthesia was associated with a significant reduction in pain or opioid use.Despite many studies showing a reduction in opioid use, the sample size of the available studies is rather small with marked between-study heterogeneity and does not reach a level of significance.Additional RCTs with congruent outcome measures would allow a more robust meta-analysis that would elucidate the true effect of regional anesthesia on pain and opioid use.
Reducing pain and postoperative complications has been associated with a shorter LOS, which is important for reducing hospital costs [52,53].Several studies in this review found a significant reduction in LOS in patients receiving a regional block in hip arthroscopy [27,30,32,36,[41][42][43], which highlights the potential for the regional blockade to reduce hospital costs by decreasing patient time in the PACU.However, when including the outcomes of all studies, most found that regional anesthesia did not reduce the overall LOS in patients undergoing hip arthroscopy.While this may be due to the lack of additional benefit from PNB in reducing LOS, there was also significant between-study heterogeneity in LOS as an outcome measure, making the true effect of PNB on LOS difficult to analyze.This highlights the need for future prospective studies with large sample sizes, perhaps multicenter prospective studies, to truly elucidate the effect regional anesthesia has on pain, opioid use and LOS.
The overall complication rate in patients undergoing hip arthroscopy was low (3.10%), with falls accounting for 37% of complications in our study.Of the 31 falls reported, FNB was responsible for 25 (80.65%).This increased rate of falls with FNB in hip arthroscopy is consistent with the existing literature highlighting this risk [18,24,29,34].In addition to falls, peripheral neuritis accounted for 25% of the reported complications in this study.Previous studies estimate that ∼0.4-13.3% of patients experience neurological complications when undergoing hip arthroscopy with a PNB [54], with long-term nerve injury occurring <1% of the time [55].While not an independent risk factor, the intrafascicular, high-pressure injections associated with PNB have been linked to peripheral nerve injury [54].Ultrasound guidance continues to be the safest way to perform PNB to avoid neurological complications [56].
In addition to providing safe guidance for performing PNB, ultrasound guidance has recently been used to perform targeted anesthesia techniques like LIA [56,57].Given the complex innervation of the hip joint, a complete sensory blockade is difficult to achieve.The effective blockade of the hip joint must include the femoral nerve, sciatic nerve, superior gluteal nerve and obturator nerve, each of which innervates a unique component of the hip [58].LIA can be beneficial in providing targeted pain relief in areas that are not anesthetized by PNB.In our review, 17% of patients underwent LIA alone or combined with a PNB.Despite some studies showing improvement in pain control, opioid use and LOS compared with GA [32,34,35], most studies suggest that LIA alone or in combination with PNB did not outperform other regional anesthesia or GA alone in pain control, opioid use or LOS in hip arthroscopy procedures.
Moreover, a recent technique developed by Philip Peng may provide superior relief by anesthetizing smaller distal sensory nerve branches with less risk of motor blockade [59].When compared with FNB, the PENG approach provided superior pain control and preserved quadriceps strength for patients undergoing hip fracture surgery [60].Three studies included in this review demonstrate a significant reduction in pain, opioid use or LOS with the PENG approach compared with GA alone [48][49][50].Future prospective studies need to be conducted in order to perform a more robust meta-analysis on the efficacy of the PENG technique in hip arthroscopy.
This study is not without limitations.Due to the significant heterogeneity of outcome measures between studies, we could not pool the data for meta-analysis.The authors instead pooled similar outcome measures to standardize the data before performing a two-sample t-test and ANOVA to determine a significant difference between the means.Another limitation is that various comorbidities among patients may not have been included in individual studies.Previous studies have demonstrated that various comorbidities such as disability, opioid tolerance, surgical complexity, intraoperative fluid administration and perioperative complications affect outcome measures such as pain, opioid use and LOS [61].One study also suggests that higher levels of preoperative psychological distress may increase PACU opioid requirements [47], an outcome measure not included in this review.The inability to control for these comorbidities could have added confounding factors to our data.

Part I: conclusion
In this study, PNBs were associated with a significant decrease in VAS pain scores at discharge compared with GA alone, but there was no significant difference in PACU opioid use or LOS among perioperative pain regimens in hip arthroscopy patients.While the efficacy of regional anesthesia in hip preservation surgery has not been comprehensively shown in the literature, it continues to be utilized in many centers.Most studies in this review assess the efficacy of regional anesthesia in the acute (<24 h) phase of surgical recovery.However, differences in efficacy need to be studied in a more robust fashion, preferably looking at both longand short-term functional outcomes, which current literature is lacking.It is the hope of the authors of this review that future multicenter prospective studies will be conducted to explore these remaining questions.
L ö chel et al. found a significant difference in pain control with TAP on POD1, but there was no significant difference in pain control in all other studies or time points [62].Two studies reported a significant decrease in opioid consumption [62,66].L ö chel et al. found that the mean opioid consumption was significantly lower in the TAP group compared with GA alone.Steinthorsdottir et al. found a significant decrease in opioid consumption using 48 mg dexamethasone compared with 8 mg dexamethasone during the first 4 PODs [66].Two studies reported significantly shorter lengths of hospital stay [63,64].FICB was associated with a significantly reduced LOS compared with FNB, and LIA was associated with a significantly reduced length of hospital stay compared with lumbar epidural block and

Fig. 1 .
Fig. 1.The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flow chart.

Fig. 3 .
Fig. 3.The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flow chart.

Table I . Summary of perioperative pain management studies in hip arthroscopy
3. The mean PACU DVPRS was 3.3.The mean PACU opioid consumption was 13.2 MME.The mean PACU LOS was 154 min.The mean pain scores, opioid use and LOS for each block type are outlined in Table II.

Table I . (Continued)
Efficacy of regional anesthesia in hip preservation surgeries• 91 Table I. (Continued) 92 • E. M. Banks et al.Table I. (Continued) Efficacy of regional anesthesia in hip preservation surgeries • 93 Table I. (Continued) 94 • E. M. Banks et al.Table I. (Continued) Efficacy of regional anesthesia in hip preservation surgeries • 95 Table I. (Continued) 96 • E. M. Banks et al.Table I. (Continued) CSE: combined spinal epidural; PA: periacetabular; IA: intraarticular; NR: not reported.Bold values denote statistical significance at the P < 0.05 level.a Converted from mg oxycodone to MME.Efficacy of regional anesthesia in hip preservation surgeries • 97

Table II . Hip arthroscopy outcomes by intervention
NR: not reported.

Table IV . Summary of perioperative pain management studies in periacetabular osteotomy and surgical hip dislocation
100 • E. M. Banks et al.
NR: not reported.Bold values denote statistical significance at the P < 0.05 level.a Reported as median.