Femoral and obturator neuropathies

The femoral and obturator nerves both arise from the L2, L3, and L4 spinal nerve roots and descend into the pelvis before emerging in the lower limbs. The femoral nerve's primary function is knee extension and hip flexion, along with some sensory innervation to the leg. The obturator nerve's primary function is thigh adduction and sensory innervation to a small area of the medial thigh. Each may be injured by a variety of potential causes, many of them iatrogenic. Here, we review the anatomy of the femoral and obturator nerves and the clinical features and potential etiologies of femoral and obturator neuropathies. Their necessary investigations, including electrodiagnostic studies and imaging, their prognosis, and potential treatments, are discussed in this chapter.

A reduced concentration femoral nerve block is effective for perioperative pain control following ACL reconstruction: a retrospective review

INTRODUCTION

Femoral nerve block (FNB) is a routinely used regional analgesic technique for anterior cruciate ligament (ACL) reconstruction. One method to balance the analgesic effect and functional impairment of FNBs may be to control the concentration of local anesthetics utilized for the block.

MATERIALS AND METHODS

Retrospective chart review was performed on 390 consecutive patients who underwent ACL reconstruction between June 2014 and May 2017. Patients were divided into those who received a standard (0.5%-bupivacaine) or low (0.1-0.125%-bupivacaine) concentration single-shot FNB performed with ultrasound guidance. Maximum postoperative VAS, Post-Anaesthesia Care Unit (PACU) time prior to discharge, need for additional 'rescue' block, and intravenous postoperative narcotic requirements were recorded.

RESULTS

A total of 268 patients (28.4 ± 11.9 years) were included for final analysis, with 72 patients in the low-concentration FNB group and 196 patients receiving the standard concentration. There were no differences in the maximum postoperative VAS between the low (6.4 ± 2.5) and standard (5.7 ± 2.9) concentration groups (P = 0.08). Similarly, the time from PACU arrival to discharge was not different between groups (P = 0.64). A sciatic rescue block was needed in 22% of patients with standard-dose FNB compared to 30% of patients receiving the low-concentration FNB (P = 0.20). Patients with a hamstring autograft harvest were more likely to undergo a postoperative sciatic rescue block compared to a bone-patellar tendon autograft (P = 0.005), regardless of preoperative block concentration. Quadriceps activation was preserved with low-concentration blocks.

CONCLUSIONS

Using 1/5th to 1/4th the standard local anesthetic concentration for preoperative femoral nerve block in ACL reconstruction did not significantly differ in peri-operative outcomes, PACU time, need for rescue blockade, or additional immediate opioid requirements.

LEVEL OF EVIDENCE

III.

Iatrogenic femoral nerve injuries: Analysis of medico-legal issues through a scoping review approach

Purpose

Accidental femoral nerve injury is a well-known iatrogenic complication of orthopaedic, abdominal, and pelvic surgery. Because of the largely transitory nature of the symptoms associated with nerve damage, its true incidence is in all likelihood underestimated. This work aims to illustrate the surgical contexts within which this nerve injury is reported, based on the evidence obtained from a Scoping Review of the literature of the last 20 years, with specific reference to the underlying etiopathogenetic mechanisms and prognostic outcomes, to highlight the evaluation issues of medico-legal interest related to this pathology.

Methods

We conducted a Scoping Review of iatrogenic femoral nerve injuries reported between 2000 and 2021 by searching the electronic databases Pubmed, Scopus, Ovid Medline, Ovid Emcare, and Web of Science.We conducted the review according to the five-step methodology outlined by Arksey and O'Malley.

Results

The literature search identified 104 papers, including case reports, case series, and retrospective studies. Surgical contexts within which iatrogenic femoral nerve injuries were reported include orthopaedic, abdominal, gynaecological, urological, vascular, and plastic surgery, as well as locoregional anaesthesiological procedures. The long-term prognosis was generally favourable.

Conclusions

Because of its frequent iatrogenic genesis, femoral nerve injury is a topic of intense medico-legal interest. From the perspective of estimating the patient's disability, the mostly favourable nature of the prognosis makes the medico-legal assessment, in some respects, complex, thus requiring a precise evaluation methodology.

Combination of femoral triangle block and infiltration between the popliteal artery and the capsule of the posterior knee (iPACK) versus local infiltration analgesia for analgesia after anterior cruciate ligament reconstruction: a randomized controlled triple-blinded trial

BACKGROUND AND OBJECTIVES

Femoral triangle block and local infiltration analgesia are two effective analgesic techniques after anterior cruciate ligament reconstruction. Recently, the iPACK block (infiltration between the popliteal artery and the capsule of the posterior knee) has been described to relieve posterior knee pain. This randomized controlled triple-blinded trial tested the hypothesis that the combination of femoral triangle block and iPACK provides superior analgesia to local infiltration analgesia after anterior cruciate ligament reconstruction.

METHODS

Sixty patients undergoing anterior cruciate ligament reconstruction received general anesthesia and were randomly allocated to two groups: femoral triangle block and iPACK under ultrasound guidance or local infiltration analgesia. For each group, a total of 160 mg of ropivacaine was injected. Postoperative pain treatment followed a predefined protocol with intravenous morphine patient-controlled analgesia, acetaminophen, and ibuprofen. The primary outcome was cumulative intravenous morphine consumption at 24 hours postoperatively. Secondary pain-related outcomes included pain scores (Numeric Rating Scale out of 10) measured at 2 and 24 hours postoperatively. Functional outcomes, such as range of motion and quadriceps strength, were also recorded at 24 postoperative hours, and at 4 and 8 postoperative months.

RESULTS

Cumulative intravenous morphine consumption at 24 hours postoperatively was significantly reduced in the femoral triangle block and iPACK group (femoral triangle block and iPACK: 9.7 mg (95% CI: 6.7 to 12.7); local infiltration analgesia: 17.0 mg (95% CI: 11.1 to 23.0), p=0.03). Other pain-related and functional-related outcomes were similar between groups.

CONCLUSIONS

The combination of femoral triangle block and iPACK reduces intravenous morphine consumption during the first 24 hours after anterior cruciate ligament reconstruction, when compared with local infiltration analgesia, without effect on other pain-related, early, or late functional-related outcomes.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT03680716).

Adductor canal block versus local infiltration analgesia for postoperative pain after anterior cruciate ligament reconstruction: a single centre randomised controlled triple-blinded trial

BACKGROUND

Both the adductor canal block (ACB) and local infiltration analgesia (LIA) are effective analgesic techniques after anterior cruciate ligament (ACL) reconstruction, but they have never been compared head-to-head. This randomised controlled triple-blinded trial tested the hypothesis that ACB provides superior analgesia to LIA after ACL reconstruction, with additional focus on postoperative functional outcomes.

METHODS

Of 104 enrolled ACL reconstruction patients receiving general anaesthesia, 52 were randomly allocated to either ACB under ultrasound guidance or LIA. For each intervention, ropivacaine 0.5%, 20 ml was injected. Postoperative pain treatment followed a predefined protocol with i.v. patient-controlled morphine, paracetamol, and ibuprofen. The primary outcome was cumulative i.v. morphine consumption at 24 h after operation. Secondary pain-related outcomes included resting and dynamic pain scores (numeric rating scale out of 10) measured 2, 24, and 48 h after operation and cumulative i.v. morphine consumption 2 and 48 h after operation. Early function-related outcomes evaluated were quadriceps strength, walking distance, and range of motion, all measured 24 and 48 h after operation. Late function-related outcomes were concentric quadriceps strength, single-hop test, triple-hop test, cross-over test, and Y balance test, measured at 4 and 8 postoperative months.

RESULTS

Cumulative i.v. morphine consumption at 24 h was similar between groups (ACB group: 17.1 mg [95% confidence interval, CI: 13.1, 21.2]; LIA group: 17.7 mg [95% CI: 13.2, 22.6], P=0.84). Similarly, no differences between groups were seen in the secondary pain- or function-related outcomes.

CONCLUSIONS

ACB and LIA result in equivalent postoperative opioid consumption with similar impact on postoperative pain scores and functional outcomes.

CLINICAL TRIAL REGISTRATION

NCT02524652.

The Effect of Femoral Nerve Block on Quadriceps Strength in Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To assess the isokinetic, functional, and patient-reported outcomes of femoral nerve block (FNB) compared with traditional multimodal anesthesia for FNB in anterior cruciate ligament (ACL) reconstruction.

METHODS

A systematic search of PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature, Cochrane Reviews, and Google Scholar was conducted according to the 2009 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Effects of FNB on quadriceps function were evaluated by isokinetic testing, functional scoring systems, range of motion, and patient self-report questionnaires. Heterogeneous reporting of outcomes precluded a formal meta-analysis. The methodologic merit of all studies included was evaluated by the Coleman Methodology Score.

RESULTS

Six studies were identified with outcome measures reported between 7 days and 6 months postoperatively. At 6 months, 2 of 4 studies that reported isokinetic testing found significantly greater deficits among patients who received a nerve block; one of the remaining studies showed a deficit at 6 weeks but not 6 months. Limited data showed no significant differences in functional or patient-reported outcomes at 6 months after reconstruction, and data regarding the impact of FNB on return to sport were inconclusive. The mean Coleman Methodology Score for the included studies was 53, indicating poor overall methodologic quality of the available literature.

CONCLUSIONS

The limited data available suggest that FNB causes a measurable deficit in quadriceps isokinetic strength during the early postoperative period but has no effect on functional outcomes or return to sport at 6 months after ACL reconstruction. However, current clinical evidence is not sufficient to draw any valid or definitive conclusions regarding the effect of FNB on postoperative outcomes after ACL reconstruction.

LEVEL OF EVIDENCE

Level IV, systemic review of Level I through IV studies.

Electrophysiological Study of Femoral Nerve Function After a Continuous Femoral Nerve Block for Anterior Cruciate Ligament Reconstruction: A Randomized, Controlled Single-Blind Trial

BACKGROUND

A continuous femoral nerve block (CFNB) is an effective analgesic treatment after anterior cruciate ligament (ACL) reconstruction but may result in transient femoral nerve injuries and quadriceps muscle weakness, which in turn contribute to worsened functional outcomes.

PURPOSE

To compare electrophysiological criteria of a femoral nerve injury as well as functional and pain-related outcomes after ACL reconstruction when analgesia was provided by a CFNB or intravenous patient-controlled analgesic of morphine (IV PCA).

STUDY DESIGN

Randomized controlled clinical trial; Level of evidence, 1.

METHODS

A total of 74 patients scheduled for ACL reconstruction were randomized to receive a CFNB before surgery, followed by a ropivacaine infusion for 2 days and oxycodone, or IV PCA. The primary outcome was the rate of femoral nerve injuries at 4 weeks postoperatively, defined as a reduction of the compound muscle action potential (CMAP) area from the vastus medialis muscle after supramaximal femoral nerve stimulation at the groin, associated with an absent H-reflex of the femoral nerve and signs of vastus medialis muscle denervation. Secondary functional outcomes were quadriceps muscle strength, active flexion range, and distance walked, as measured on postoperative days 1 and 2. Secondary pain-related outcomes were IV morphine consumption and pain scores at rest and on movement in phase 1 recovery and on postoperative days 1 and 2.

RESULTS

No patients met the electrophysiological criteria of a femoral nerve injury. The mean CMAP area at 4 weeks was equivalent in both the CFNB and IV PCA groups (47 ± 16 mV·ms and 51 ± 13 mV·ms, respectively; P = .50). While no differences were detected in functional outcomes or pain scores, the consumption of an IV morphine equivalent was reduced by the administration of a CFNB in phase 1 recovery (6 ± 5 mg and 13 ± 7 mg, respectively; P = .0003), on postoperative day 1 (6 ± 7 mg and 19 ± 17 mg, respectively; P = .0005), and on postoperative day 2 (11 ± 10 mg and 19 ± 17 mg, respectively; P = .03) compared with an IV PCA.

CONCLUSION

Despite prior contrary reports, a CFNB did not result in femoral nerve injuries or worsened functional outcomes after ACL reconstruction. The improvement of analgesia with a CFNB was only marginal and not clinically relevant beyond 24 hours. Registration: NCT01321138 ( ClinicalTrials.gov identifier).

Femoral nerve block is associated with persistent strength deficits at 6 months after anterior cruciate ligament reconstruction in pediatric and adolescent patients

BACKGROUND

Femoral nerve block (FNB) has become a popular method of postoperative analgesia for anterior cruciate ligament (ACL) reconstruction in pediatric and adolescent patients. Successful rehabilitation after surgery involves return of quadriceps and hamstring strength.

PURPOSE

To compare knee strength and function 6 months after ACL reconstruction in pediatric and adolescent patients who received FNB versus patients with no nerve block.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients 18 years or younger who underwent primary ACL reconstruction between 2000 and 2010 at a single institution were identified. If the patient was skeletally immature, a transphyseal ACL reconstruction was performed. Of these patients, 68% underwent reconstruction with a patellar tendon autograft, and in 32% of patients a hamstring autograft was utilized. There were 124 patients who met the study inclusion criteria, including 62 in the FNB group (31 males, 31 females) and 62 patients in the control group (25 males, 37 females). All study patients participated in a comprehensive rehabilitation program that included isokinetic strength and functional testing at 6 months postoperatively.

RESULTS

Univariate analysis showed a significantly higher deficit at 6 months in the FNB group with respect to fast isokinetic extension strength (17.6% vs 11.2%; P = .01) as well as fast (9.9% vs 5.7%; P = .04) and slow (13.0% vs 8.5%; P = .03) isokinetic flexion strength. There was no difference in slow isokinetic extension strength deficit between the 2 groups (FNB, 22.3% vs control, 18.7%; P = .20). With respect to function, there were no differences in deficit for vertical jump (FNB, 9.4% vs control, 11.3%; P = .30), single hop (7.6% vs 7.5%; P = .96), or triple hop (8.0% vs 6.6%; P = .34) between the 2 groups. A significantly higher percentage of patients in the control group met functional and isokinetic criteria for return to sports at 6 months (90.2% vs 67.7%; odds ratio, 4.37; P = .002).

CONCLUSION

Pediatric and adolescent patients treated with FNB for postoperative analgesia after ACL reconstruction had significant isokinetic deficits in knee extension and flexion strength at 6 months when compared with patients who did not receive a nerve block. Patients without a block were 4 times more likely to meet criteria for clearance to return to sports at 6 months.

[Ultrasound and nerve stimulator guided continuous femoral nerve block analgesia after total knee arthroplasty: a multicenter randomized controlled study]

BACKGROUND AND OBJECTIVES

Postoperative analgesia is crucial for early functional excise after total knee arthroplasty. To investigate the clinical efficacy of ultrasound and nerve stimulator guided continuous femoral nerve block analgesia after total knee arthroplasty.

METHODS

46 patients with ASA grade I-III who underwent total knee arthroplasty received postoperative analgesia from October 2012 to January 2013. In 22 patients, ultrasound and nerve stimulator guided continuous femoral nerve block were performed for analgesia (CFNB group); in 24 patients, epidural analgesia was done (PCEA group). The analgesic effects, side effects, articular recovery and complications were compared between two groups.

RESULTS

At 6h and 12h after surgery, the knee pain score (VAS score) during functional tests after active exercise and after passive excise in CFNB were significantly reduced when compared with PCEA group. The amount of parecoxib used in CFNB patients was significantly reduced when compared with PCEA group. At 48h after surgery, the muscle strength grade in CFNB group was significantly higher, and the time to ambulatory activity was shorter than those in PCEA group. The incidence of nausea and vomiting in CFNB patients was significantly reduced when compared with PCEA group.

CONCLUSION

Ultrasound and nerve stimulator guided continuous femoral nerve block provide better analgesia at 6h and 12h, demonstrated by RVAS and PVAS. The amount of parecoxib also reduces, the incidence of nausea and vomiting decreased, the influence on muscle strength is compromised and patients can perform ambulatory activity under this condition.

Femoral nerve block: Assessment of postoperative analgesia in arthroscopic anterior cruciate ligament reconstruction

BACKGROUND AND OBJECTIVES

Knee anterior cruciate ligament reconstruction (ACLR) may be painful in the postoperative period. The primary objective of this study was to evaluate whether the use of femoral nerve block (FNB) associated with spinal anesthesia would improve the postoperative pain treatment in ACLR and the secondary objectives were to evaluate tramadol request and adverse events.

METHOD

53 patients were randomly divided into two groups: GA (n =26) received spinal anesthesia and GB (n = 27) received spinal anesthesia and FNB. All patients received multimodal analgesia and rescue analgesics could be requested anytime. Assessments were performed at 6, 12 and 24 hours.

RESULTS

There was no difference between both groups regarding demographic and clinical- surgical variables. There was no difference between groups regarding pain intensity. Mean pain scores were higher at 12 hours in GA and there was no change in GB; 55.6% of patients reported moderate pain in GA and 53.8% mild pain in GB. There was no difference regarding tramadol request. There were no serious adverse events: 80.8% of patients in GB had motor block of the thigh and two fell.

CONCLUSIONS

Analgesia was more effective with the combination of spinal and FNB, which allowed better control of postoperative pain, assessed 12 hours after anesthesia. There was no difference in tramadol request. Patients in this study had no serious adverse events; however, one must be attentive to motor paralysis and the possibility of falling when FNB is performed.