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

Radiographic Changes After Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients Compared With an Age- and Sex-Matched Cohort

BACKGROUND

Despite recent evidence that medial patellofemoral ligament reconstruction (MPFLR) in the skeletally immature patient is both safe and effective, there are limited data evaluating postoperative coronal- and sagittal-plane growth and radiographic patellofemoral parameters in this population.

PURPOSE

The primary purpose was to assess radiographic measures of coronal-plane alignment, longitudinal growth, patellar congruence, and trochlear dysplasia after MPFLR in a skeletally immature population. A secondary purpose was to assess this population compared with a matched cohort with a focus on trochlear dysplasia prevalence and the effect of MPFLR on patellar height.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 28 children with a minimum 1-year follow-up who underwent isolated MPFLR were identified. All patients were skeletally immature, defined as fully open physes on both sides of the knee joint, at the time of surgery. The development of a limb length discrepancy or angular growth abnormalities were assessed on standing hip-to-ankle radiographs, patellar tilt and congruence were measured on the Merchant view of the knee, and the grade of trochlear dysplasia and patellar height were assessed on lateral knee radiographs. A sex- and age-matched group of patients who underwent anterior cruciate ligament reconstruction was formed as a control for patellar height and trochlear dysplasia measurements.

RESULTS

The mean patient age was 11.71 ± 2.02 years at the time of surgery with a mean follow-up of 23.54 ± 12.49 months. All but 1 patient in the MPFLR group had preoperative features consistent with trochlear dysplasia. There was no significant difference in limb length or coronal-plane alignment at final follow-up (P = .725 and P > .999, respectively). Both the MPFLR and the anterior cruciate ligament reconstruction groups had a statistically significant decrease in the Caton-Deschamps index between the preoperative and postoperative time points (mean, 0.18 ± 0.20 and 0.11 ± 0.14, respectively; P = .161).

CONCLUSION

MPFLR may be safely performed utilizing an epiphyseal femoral socket in a skeletally immature cohort without affecting normal longitudinal growth or coronal limb alignment. The previously reported effect of MPFLR in reducing patellar height may be related to physiological growth based on similar changes noted in a comparison cohort that did not undergo the procedure.

Network meta-analysis of the analgesic effectiveness of regional anaesthesia techniques for anterior cruciate ligament reconstruction

Anterior cruciate ligament reconstruction can cause moderate to severe acute postoperative pain. Despite advances in our understanding of knee innervation, consensus regarding the most effective regional anaesthesia techniques for this surgical population is lacking. This network meta-analysis compared effectiveness of regional anaesthesia techniques used to provide analgesia for anterior cruciate ligament reconstruction. Randomised trials examining regional anaesthesia techniques for analgesia following anterior cruciate ligament reconstruction were sought. The primary outcome was opioid consumption during the first 24 h postoperatively. Secondary outcomes were: rest pain at 0, 6, 12 and 24 h; area under the curve of pain over 24 h; and opioid-related adverse effects and functional recovery. Network meta-analysis was conducted using a frequentist approach. A total of 57 trials (4069 patients) investigating femoral nerve block, sciatic nerve block, adductor canal block, local anaesthetic infiltration, graft-donor site infiltration and systemic analgesia alone (control) were included. For opioid consumption, all regional anaesthesia techniques were superior to systemic analgesia alone, but differences between regional techniques were not significant. Single-injection femoral nerve block combined with sciatic nerve block had the highest p value probability for reducing postoperative opioid consumption and area under the curve for pain severity over 24 h (78% and 90%, respectively). Continuous femoral nerve block had the highest probability (87%) of reducing opioid-related adverse effects, while local infiltration analgesia had the highest probability (88%) of optimising functional recovery. In contrast, systemic analgesia, local infiltration analgesia and adductor canal block were each poor performers across all analgesic outcomes. Regional anaesthesia techniques that target both the femoral and sciatic nerve distributions, namely a combination of single-injection nerve blocks, provide the most consistent analgesic benefits for anterior cruciate ligament reconstruction compared with all other techniques but will most likely impair postoperative function. Importantly, adductor canal block, local infiltration analgesia and systemic analgesia alone each perform poorly for acute pain management following anterior cruciate ligament reconstruction.

General, spinal or regional anaesthesia does not affect strength performance 6 months after ACL reconstruction

PURPOSE

The recovery of strength is a key element in successfully returning to sports after ACL reconstruction. The type of anaesthesia has been suspected an influential factor in the post-operative recovery of muscle function.

METHODS

In this retrospective analysis, n = 442 consecutive patients undergoing primary isolated ACL reconstruction using a hamstring autograft were analysed by pre- and post-operative isokinetic tests in a single orthopaedic centre. These were subdivided into four cohorts: (1) general anaesthesia (n = 47), (2) general anaesthesia with prolonged (48 h) on-demand femoral nerve block (n = 37), (3) spinal anaesthesia (n = 169) and (4) spinal anaesthesia with prolonged (48 h) on-demand femoral nerve block (n = 185). Primary outcome was the change from pre- to post-operative isokinetic strength during knee extension and flexion.

RESULTS

Using one-way ANOVA, there was no significant influence of the type of anaesthesia. The main effect of anaesthesia on change in extension forces was not significant, and effect sizes were very small (n.s.). Similarly, the main effect of anaesthesia on change in flexion forces was statistically not significant (n.s.).

CONCLUSIONS

The findings of this study support the interpretation that the type of anaesthesia has no significant effect on the ability to recover thigh muscle strength 6 months after isolated hamstring ACL reconstruction. With regard to the recovery of athletic performance and return-to-sports testing criteria, there is no reason to avoid regional anaesthesia.

LEVEL OF EVIDENCE

III.

Periarticular injection and hamstring block versus placebo for pain control in anterior cruciate ligament reconstruction: A randomized controlled trial

PURPOSE

To study the effectiveness of periarticular infiltration (PI), including the proximal donor site vs. placebo in anterior cruciate ligament (ACL) reconstruction.

METHOD

A total of 44 patients were randomized in two groups assigned to receive PI or placebo. The perioperative protocol was the same for both groups. The principal outcome was pain measured at 8 and 24 h by a visual analog scale (VAS). The pain was registered in the knee and the proximal donor site. Pain scores were also assessed to determine whether the VAS improvement would reach the threshold values reported for the minimal clinically significant difference. The secondary outcome was the need for opioid rescue medication.

RESULTS

Patients receiving PI exhibited lower pain values in the knee at 8 h (mean PI 35.00 ± 5.76 vs. placebo 60.23 ± 4.52 p = 0.01) and at 24 h (mean PI 37.23 ± 5.62 vs. placebo 55.55 ± 3.41 p = 0.008). These results were above the threshold for clinical significance. No improvements were found in proximal donor site pain and consumption of opioid rescue medication. Complications were comparable between the two groups.

CONCLUSION

PI significantly reduced pain in the knee vs. placebo after ACL reconstruction with hamstring autograft at 8 and 24 h after surgery. The instillation of part of the mixture in the proximal hamstring stump did not result in any improvement LEVEL OF EVIDENCE I: Level I, randomized controlled trial.

The Median Effective Analgesic Concentration of Ropivacaine in Sciatic Nerve Block Guided by Ultrasound After Arthroscopic Anterior Cruciate Ligament Reconstruction: A Double-Blind Up-Down Concentration-Finding Study

Background

The median effective analgesic concentration (MEAC; EC50 = effective concentration in 50% patients) of ropivacaine in sciatic nerve block guided by ultrasound (US) required for effective postoperative analgesia following arthroscopic anterior cruciate ligament (ACL) reconstruction has not yet been found. This study aimed to determine the effectiveness of MEAC of 20 ml ropivacaine of postoperative anesthesia for patients after ACL reconstruction.

Methods

In total, 29 patients who underwent elective arthroscopic ACL reconstruction were enrolled in this study. All the subjects were given 20 ml of 0.2% ropivacaine for femoral nerve block. A concentration of 20 ml ropivacaine administered to the sciatic nerve was measured by applying the up-and-down sequential method (UDM). The starting concentration was 0.2% in the first patient, and the next patient received decremented 0.025% ropivacaine if the prior patient's postoperative visual analog pain score was <4 in the initial 8 h. Otherwise, the participant was given an incremental dose of 0.025% ropivacaine. The EC50 of ropivacaine was determined by using centered isotonic, linear-logarithmic, exponential regressions, and linear regression. The “goodness of fit” was compared among various models by calculating the residual standard errors.

Results

The concentration of ropivacaine administered ranged from 0.1 to 0.2%. The EC50 [95% confidence interval (CI)] determined by four statistical methods (centered isotonic, exponential regressions, linear-logarithmic, and linear regression) was 0.115, 0.113% (0.108, 0.343%), 0.142% (0.112, 0.347%), and 0.129% (0.103, 0.359%), respectively. Among all models, the residual standard error was the smallest for the exponential regression (0.2243).

Conclusion

The EC50 of ropivacaine in US-guided sciatic nerve block was 0.113–0.142%, and exponential regression model best matched the data.

Most Analgesia Treatments Have No Clinical Significance for Anterior Cruciate Ligament Reconstruction: A Network Meta-analysis of 66 Randomized Controlled Trials

PURPOSE

To assess the relative efficacy of several clinical treatments for postoperative analgesia of anterior cruciate ligament reconstruction through network meta-analysis based on multiple published randomized controlled trials.

METHODS

We searched PubMed, the Cochrane library, EMBASE, and Web of Science, each from inception until February 15, 2021. Outcomes including pain scores at rest (visual analog scale, numerical rating scales, and other scales, which were converted to a standardized 0-10 scale), morphine consumption, and complications were meta-analyzed. Quality of the included studies was assessed using the Cochrane risk-of-bias tool. The authors defined the best choice for postoperative analgesia as the one that had significant difference in pain scores, morphine consumption, and had no significant difference in the risk of complications compared with placebo in the initial 48 postoperative hours.

RESULTS

In total, 66 studies with 4,168 patients were included in this network meta-analysis. Only periarticular infiltration was significantly superior to placebo in pain scores and morphine consumption (pain at 2 hours: mean difference [MD] -0.74, 95% confidence interval [CI] -1.36 to -0.12; pain at 6 hours: MD -0.81, 95% CI -1.42 to -0.21; pain at 12 hours: MD -0.85, 95% CI -1.53 to -0.17; pain at 24 hours: MD -0.80, 95% CI -1.19 to -0.40; morphine consumption at 24 hours: MD -10.12, 95% CI -14.31 to -5.93; morphine consumption at 48 hours: MD -5.62, 95% CI -6.74 to -4.51). Periarticular infiltration did not increase the risk of complications compared with placebo (nausea and vomiting: odds ratio [OR] 0.63, 95% CI 0.34-1.16; pruritus: OR 0.74, 95% CI 0.35-1.58; urinary retention: OR 0.55, 95% CI 0.25-1.23). In addition, There was no significant difference between adductor canal block and femoral nerve block in pain scores and morphine consumption (pain at 2 hours: MD -0.01, 95% CI -1.44 to 1.42; pain at 6 hours: MD 0.29, 95% CI -0.28 to 0.86; pain at 12 hours: MD 0.36, 95% CI -0.44 to 1.16; pain at 24 hours: MD 0.26, 95% CI -0.22 to 0.75; pain at 48 hours: MD -0.36, 95% CI -0.97 to 0.24; morphine at 24 hours: MD 1.04, 95% CI -4.70 to 6.79; morphine at 48 hours: MD -0.32, 95% CI -0.70 to 0.07; postoperative nausea and vomiting: OR 1.07, 95% CI 0.55-2.09; pruritus: OR 1.36, 95% CI 0.66-2.79; urinary retention: OR 1.41, 95% CI 0.37-5.29).

CONCLUSIONS

Based on current evidence, most analgesic methods could result in lower pain scores and decrease morphine consumption when compared with placebo; however, differences between methods were small and inconsistent. There seemed to be no significant difference between adductor canal block and femoral nerve block in pain score, morphine consumption and complications.

LEVEL OF EVIDENCE

Level I, meta-analysis of Level I RCTs.

Anterior cruciate ligament reconstruction with ultrasound-guided femoral nerve block does not adversely affect knee extensor strength beyond that seen with intravenous patient-controlled analgesia at 3 and 6 months postoperatively

BACKGROUND

This study aimed to investigate the effect of anterior cruciate ligament (ACL) reconstruction with an ultrasound-guided femoral nerve block (FNB) on knee extensor strength weakness 3 and 6 months, and graft rupture in the 1 year following ACL reconstruction.

METHODS

One hundred and seven patients who underwent ACL reconstruction were included in this retrospective study. The patients were divided into two groups stratified by the method of postoperative pain management. The FNB group included 66 patients, and there were 41 patients in the intravenous patient-controlled analgesia (iv-PCA) group. The isokinetic peak torque of knee flexor and extensor was measured preoperative, 3 and 6 months after ACL reconstruction. Muscle strength measurements were performed using the BIODEX dynamometer at a velocity of 60°/s and 180°/s. Peak torque of knee extensor and flexor strength, estimated pre-injury capacity (EPIC), body weight ratio (BW), and graft rupture incidence were compared between the two groups.

RESULTS

There were no statistically significant differences in the knee extensor and flexor strength for all items at 3 and 6 months after ACL reconstruction. There was also not a statistically significant difference in the graft rupture incidence between the two groups: FNB group was two patients, 3.0% vs. iv-PCA group was one patient, 2.4% (p = 0.86).

CONCLUSION

ACL reconstruction with ultrasound-guided FNB does not affect knee extensor strength at 6 months, nor graft rupture at 1 year postoperatively.

Quadriceps and Hamstring Strength in Adolescents 6 Months After ACL Reconstruction With Femoral Nerve Block, Adductor Canal Block, or No Nerve Block

Background:

Femoral nerve block (FNB) and adductor canal block (ACB) have been used increasingly for pain control during anterior cruciate ligament (ACL) reconstruction in adolescent patients. However, recent evidence suggests that the use of FNB may affect quadriceps strength recovery 6 months after surgery.

Purpose/Hypothesis:

To compare postoperative isokinetic strength in adolescents who received FNB, ACB, or no block for perioperative analgesia during ACL reconstruction. We anticipated lower postoperative quadriceps and hamstring isokinetic deficits in adolescents who received FNB as compared with ACB.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients were included in the study if they had undergone hamstring tendon autograft ACL reconstruction by a single surgeon from July 2008 to January 2018 and if they underwent isokinetic muscle testing at 4 to 8 months postoperatively. The participants were divided into 3 groups (no block, FNB, and ACB), and we compared the deficit in percentages between the affected and unaffected limbs as calculated from the isokinetic quadriceps and hamstring strength testing at 60 and 180 deg/s. Between-group analysis was performed using analysis of variance, with an alpha of .05.

Results:

A total of 98 participants were included in the analysis (31 no block, 36 FNB, and 31 ACB). The mean ± SD age of the patients was 15.26 ± 1.15, 15.50 ± 1.42, and 15.71 ± 1.44, for no block, FNB, and ACB, respectively. At 5.61 months postoperatively, there was no significant difference across the 3 groups in isokinetic quadriceps deficits (P ≥ .99), and the only significant difference in isokinetic hamstring deficit was observed for peak flexion at 180 deg/s, in which the ACB group had lower peak torque than the FNB group (–9.80% ± 3.48% vs 2.37% ± 3.23%; P = .035). The ratio of participants with a deficit exceeding 15% did not differ significantly among the 3 groups.

Conclusion:

Contrary to previous research, our findings indicate only minimal difference in quadriceps strength among the 3 types of perioperative analgesia in adolescents approximately 6 months after ACL reconstruction. The only significant strength deficit was seen in the hamstrings of patients receiving ACB at peak flexion as compared with those receiving FNB.

Rupture, reconstruction, and rehabilitation: A multi-disciplinary review of mechanisms for central nervous system adaptations following anterior cruciate ligament injury

BACKGROUND

Despite surgical reconstruction and extensive rehabilitation, persistent quadriceps inhibition, gait asymmetry, and functional impairment remain prevalent in patients after anterior cruciate ligament (ACL) injury. A combination of reports have suggested underlying central nervous system adaptations in those after injury govern long-term neuromuscular impairments. The classic assumption has been to attribute neurophysiologic deficits to components of injury, but other factors across the continuum of care (e.g. surgery, perioperative analgesia, and rehabilitative strategies) have been largely overlooked.

OBJECTIVE

This review provides a multidisciplinary perspective to 1) provide a narrative review of studies reporting neuroplasticity following ACL injury in order to inform clinicians of the current state of literature and 2) provide a mechanistic framework of neurophysiologic deficits with potential clinical implications across all phases of injury and recovery (injury, surgery, and rehabilitation) RESULTS: Studies using a variety of neurophysiologic modalities have demonstrated peripheral and central nervous system adaptations in those with prior ACL injury. Longitudinal investigations suggest neurophysiologic changes at spinal-reflexive and corticospinal pathways follow a unique timecourse across injury, surgery, and rehabilitation.

CONCLUSION

Clinicians should consider the unique injury, surgery, anesthesia, and rehabilitation on central nervous system adaptations. Therapeutic strategies across the continuum of care may be beneficial to mitigate maladaptive neuroplasticity in those after ACL injury.

[Comparison between subarachnoid morphine and femoral nerve block for analgesia after knee ligament reconstruction: a randomized clinical trial]

BACKGROUND AND OBJECTIVES

There is no consensus of the ideal technique to provide analgesia in knee ligament reconstructions. The aim of this study was to compare the intensity of postoperative pain in these patients under different modalities of analgesia.

METHOD

Randomized and controlled clinical trial of patients undergoing reconstruction of the anterior cruciate ligament (ACL) with flexor tendons between December 2013 and 2014. All patients underwent spinal anesthesia and rescue analgesia with tramadol. The Groups C, M, R0,375 and R0,25 were compared with only the previously described technique, subarachnoid morphine (100 μg) or femoral nerve block with 25 mL of 0.375% ropivacaine and 0.25%, respectively. Pain intensity at 6, 12 and 24hours, age, sex, rescue analgesia, adverse reactions and satisfaction were evaluated.

RESULTS

Among the 83 eligible patients, a predominance of males (85.7%) was observed, between 28 and 31 years. The Group C requested more opioid (27.3%) than the other groups, without significance when compared. There were no significant differences in pain intensity at 6, 12 and 24hours. There was a higher incidence of urinary retention in the Group M (23.8%) than in the R0,375 (0%) and prolonged quadriceps motor block in the R0,375 Group (30%) than in the M and C Groups (0%), with statistical significance (p < 0.05).

CONCLUSION

There was no difference in the intensity of postoperative pain in patients submitted to anterior cruciate ligament reconstruction with flexor tendons under the analgesic modalities evaluated, despite the predominance of urinary retention in the M Group and motor block in the R0,375 Group.

Comparison between subarachnoid morphine and femoral nerve block for analgesia after knee ligament reconstruction: a randomized clinical trial

Background and objectives

There are no consensus of the ideal technique to provide analgesia in knee ligament reconstructions. The aim of this study was to compare the intensity of postoperative pain in these patients under different modalities of analgesia.

Method

Randomized and controlled clinical trial of patients undergoing reconstruction of the Anterior Cruciate Ligament (ACL) with flexor tendons between December 2013 and 2014. All patients underwent spinal anesthesia and rescue analgesia with tramadol. The groups C, M, R0,375 and R0,25 was compared with only the previously described technique, subarachnoid morphine (100░μg), or Femoral Nerve Block (BNF) with 25░mL of 0.375% ropivacaine and 0.25%, respectively. Pain intensity at 6, 12 and 24░hours, age, sex, rescue analgesia, adverse reactions and satisfaction were evaluated.

Results

Among the 83 eligible patients, a predominance of males (85.7%) was observed, between 28 and 31 years. The group C requested more opioid (27.3%) than the other groups, without significance when compared. There were no significant differences in pain intensity at 6, 12 and 24░hours. There was a higher incidence of urinary retention in the M group (23.8%) than in the R0,375 (0%) and prolonged quadriceps motor block in the R0,375 group (30%) than in the M and C groups (0%), with statistical significance (p░<░0.05).

Conclusion

There was no difference in the intensity of postoperative pain in patients submitted to ACL reconstruction with flexor tendons under the analgesic modalities evaluated, despite the predominance of urinary retention in the M group and motor block in the R0,375 group.

Effects of dexmedetomidine as a perineural adjuvant for femoral nerve block: A systematic review and meta-analysis

Background

Femoral nerve block (FNB) is one of the first-line analgesic methods for patients following lower extremity surgery. However, FNB with local anesthetics alone exert limited potency and supplemental opioids are often required. Dexmedetomidine (DEX) has been used to improve the analgesic effects of FNB. The present systematic review and meta-analysis were conducted to evaluate the effectiveness of DEX as an adjuvant to local anesthetics for FNB.

Methods

Randomized controlled trials comparing the effects of DEX versus sham control in combination with local anesthetics for FNB were included in this meta-analysis. Postoperative pain scores, duration of analgesic effects, and postoperative narcotic consumption were outcomes of interest. This research was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statements.

Results

A total of 9 studies encompassing 580 participants were included for data synthesis after critical evaluation. DEX as an adjuvant with local anesthetics for FNB significantly relieved pain intensity at 12, 24 and 48 hours after surgery, both at rest (standardized mean difference -1.34 [95% CI -1.87 to -0.82], P<0.00001 at 12 h; -1.26 [-1.90 to -0.0.63], P<0.0001 at 24 h; and -1.34; [-2.18 to -0.50], P = 0.002 at 48 h) and with movement (-1.30 [-2.17 to -0.43], P = 0.004 at 12 h; -1.02 [-1.31 to -0.72], P<0.00001 at 24h; and -1.33 [-2.03 to -0.63], P = 0.0002); it also significantly prolonged analgesic duration (mean difference 7.23 h [95% CI 4.07 to 10.39], P<0.00001) and decreased opioid consumption (mean difference of morphine equivalent -12.13 mg [95% CI -23.36 to -0.89], P<0.00001). Regarding safety, DEX use increased the rate of hypotension (odds ratio 4.10, 95% CI 1.40 to 12.01, P = 0.01).

Conclusion

DEX as an adjuvant to local anesthetics for FNB improves analgesia, prolongs analgesic duration and reduces supplemental opioid consumption; but increases hypotension.

Femoral nerve catheters and limb strength asymmetry at 6 months after primary anterior cruciate ligament reconstruction in pediatric patients

BACKGROUND

The postoperative implications of single-injection femoral nerve blockade and femoral nerve catheter placement for anterior cruciate ligament reconstruction are not well defined among pediatric patients. Femoral nerve blockade may be associated with deficits in quadriceps symmetry at 6 months postoperative.

AIMS

We compared outcomes after primary anterior cruciate ligament reconstruction surgery in pediatric patients who received either a single-injection femoral nerve block or femoral nerve catheter and a single-injection popliteal nerve block.

METHODS

We conducted a retrospective chart review of patients 10-19 years of age who underwent anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft by a single orthopedic surgeon at two of our locations. Of 88 patients analyzed, 31 received single-injection femoral nerve blockade (52% female, mean age = 15.6 ± 1.8 years) and 57 received femoral nerve catheter (53% female, mean age = 15.6 ± 1.7 years). Time from surgery to return-to-sport clearance and movement symmetry were compared between groups at approximately 6 months postoperatively.

RESULTS

The single-injection femoral nerve blockade group exhibited significantly greater single-leg squat symmetry than did the femoral nerve catheter group (95.5 ± 6.7% vs 88.3 ± 9.3%; P = 0.02; mean difference = 7.2%, 95% CI = -1.1, 13.3) 6 months postoperatively. There was no difference in time from surgery to return-to-sport clearance between groups (median = 247 [interquartile range = 218-295] days vs 268 [241-331] days; P = 0.22; mean difference = 40 days; 95% CI = -23, 102).

CONCLUSION

Though time to return to sport did not differ, patients in the femoral nerve catheter group exhibited greater single-leg squat asymmetry than did those in the femoral nerve blockade group approximately 6 months postoperatively. Persistent functional deficits may be important to consider when treating pediatric patients undergoing anterior cruciate ligament reconstruction.

Effect of Adductor Canal Block Versus Femoral Nerve Block on Quadriceps Strength, Function, and Postoperative Pain After Anterior Cruciate Ligament Reconstruction: A Systematic Review of Level 1 Studies

BACKGROUND

Femoral nerve block (FNB) is a popular technique for reducing postoperative pain in patients with anterior cruciate ligament reconstruction (ACLR), but it is also linked to a number of adverse effects, such as quadriceps weakness, antalgic ambulation, and increased fall risk. Adductor canal block (ACB) has been offered as a motor nerve-sparing alternative to FNB.

PURPOSE

To evaluate available literature that compares the effects of ACB and FNB on functional outcomes after arthroscopic ACLR.

STUDY DESIGN

Systematic review.

METHODS

Following the 2009 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a search of PubMed (Ovid), CINAHL, Scopus, Cochrane, and Google Scholar databases was conducted. Search terms were designed to capture studies comparing the effects of ACB and FNB in patients undergoing arthroscopic ACLR. Data were evaluated regarding study and patient characteristics, functional measures, opioid consumption, pain scores, and complications.

RESULTS

Eight randomized controlled trials (N = 655 patients) comparing the efficacy of ACB versus FNB in arthroscopic ACLR were included. The heterogeneity of outcome measures precluded meta-analysis. Seven studies reported functional measures, which included isokinetic strength, straight-leg raise, and other various measures. Follow-up periods varied between 1 hour and 6 months. In 3 trials, ACB was found to preserve quadriceps strength as measured using straight-leg raise for the first 12 to 24 hours after surgery, while 3 other trials found no difference between the groups. No differences were reported in isokinetic strength at 6 months. In other functional measures, ACB either outperformed or was equivalent to FNB. The majority of studies reporting opioid consumption, pain scores, and complications found no differences between the blocks.

CONCLUSION

This systematic review suggests that when compared with FNB, ACB preserves quadriceps function in the early postoperative period after ACLR while providing a similar level of analgesia. Limitations of this study include the use of various functional measures and limited long-term follow-up. More research evaluating long-term functional outcomes with standardized measures is needed to draw adequate conclusions regarding the effects of ACB and FNB on function after ACLR.

Femoral nerve block at time of ACL reconstruction causes lasting quadriceps strength deficits and may increase short-term risk of re-injury

PURPOSE

To determine whether femoral nerve blockade (FNB) at the time of primary ACL reconstruction is associated with meeting isokinetic extension strength return to sport criteria near completion of physical therapy and whether FNB affects 1-year or 2-year risk of ipsilateral ACL graft rupture or contralateral native ACL injury.

METHODS

Three-hundred and sixty patients (n = 244 with FNB, n = 116 no FNB) underwent primary ACL reconstruction. All patients completed rehabilitation and underwent functional strength testing towards the end of knee rehabilitation (mean 5.6 months post-surgery). Association between FNB and isokinetic extension strength limb symmetry index (LSI) (goal LSI ≥ 90% for return to sport) as well as risk of recurrent ACL injury within first or second year after surgery was evaluated.

RESULTS

Ipsilateral or contralateral ACL injury within 2 years occurred in 11.2% of patients with FNB and 5.7% without FNB (p = 0.01). Patients with FNB had higher incidence of ipsilateral graft rupture within the first year after surgery but no difference in graft rupture during the second. Two-year risk of contralateral ACL injury was similar in both groups. At the time of initial testing, patients who received FNB had lower fast isokinetic extension LSI versus patients without FNB and were less likely achieve a goal ≥ 90% LSI; slow extension LSI was unaffected.

CONCLUSION

Use of FNB at the time of primary ACL reconstruction can negatively affect achievement of isokinetic extension strength return to sport criteria. FNB increases risk of graft rupture within the first year after surgery but does not affect re-injury risk during the second. FNB may not be appropriate for use in patients already at high risk of ACL re-injury.

LEVEL OF EVIDENCE

III.

The Influence of Perioperative Nerve Block on Strength and Functional Return to Sports After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Patients often have quadriceps or hamstring weakness after anterior cruciate ligament reconstruction (ACLR), despite postoperative physical therapy regimens; however, little evidence exists connecting nerve blocks and ACLR outcomes.

PURPOSE

To compare muscle strength at return to play in patients who received a nerve block with ACLR and determine whether a specific block type affected subjective knee function.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients were recruited 5 to 7 months after primary, isolated ACLR and completed bilateral isokinetic strength tests of the knee extensor/flexor groups as a single-session return-to-sport test. Subjective outcomes were assessed with the International Knee Documentation Committee (IKDC) score. Strength was expressed as torque normalized to mass (N·m/kg) and limb symmetry index as involved/uninvolved torque. Chart review was used to determine the type of nerve block and graft used. Nerve block types were classified as knee extensor motor (femoral nerve), knee flexor motor (sciatic nerve), or isolated sensory (adductor canal block/saphenous nerve). A 1-way analysis of covariance controlling for graft type was used.

RESULTS

A total of 169 patients were included. Graft type distribution consisted of 102 (60.4%) ipsilateral bone-patellar tendon-bone (BTB) and 67 (39.6%) ipsilateral hamstring tendon. Nerve block type distribution consisted of 38 (22.5%) femoral, 25 (14.8%) saphenous, 45 (26.6%) femoral and sciatic, and 61 (36.1%) saphenous and sciatic. No significant difference was found in knee extensor strength (P = .113) or symmetry (P = .860) between patients with knee extensor motor blocks (1.57 ± 0.45 N·m/kg; 70.1% ± 15.3%) and those without (1.47 ± 0.47 N·m/kg; 69.6% ± 18.8%). A significant difference was found between patients with knee flexor motor blocks (0.83 ± 0.26 N·m/kg) and those without (0.92 ± 0.27 N·m/kg) for normalized knee flexor strength (P = .21) but not knee flexor symmetry (P = .592). Controlling for graft type, there were no differences in subjective knee function (IKDC score) between all nerve block groups (P = .57).

CONCLUSION

Our data showed that use of a sciatic nerve block with ACLR in patients with hamstring and BTB grafts influences persistent knee flexor strength deficits at time of return to sports. Although the cause of postoperative muscular weakness is multifactorial, this study adds to the growing body of evidence suggesting that perioperative nerve blocks affect muscle strength and functional rehabilitation after ACLR.

Lower extremity regional anesthesia: essentials of our current understanding

The advent of ultrasound guidance has led to a renewed interest in regional anesthesia of the lower limb. In keeping with the American Society of Regional Anesthesia and Pain Medicine's ongoing commitment to provide intensive evidence-based education, this article presents a complete update of the 2005 comprehensive review on lower extremity peripheral nerve blocks. The current review article strives to (1) summarize the pertinent anatomy of the lumbar and sacral plexuses, (2) discuss the optimal approaches and techniques for lower limb regional anesthesia, (3) present evidence to guide the selection of pharmacological agents and adjuvants, (4) describe potential complications associated with lower extremity nerve blocks, and (5) identify informational gaps pertaining to outcomes, which warrant further investigation.