The debate over peripheral nerve blockade (PNB) for tibia fractures remains contentious in trauma centers worldwide. Anesthesiologists champion PNB due to its safety, quick administration, superior analgesia, reduced need for systemic medications—especially opioids—and potential improvement in blood flow to an injured limb.1 Conversely, orthopedic and trauma surgeons warn that PNB can mask early signs of acute compartment syndrome (ACS), such as disproportionate pain and neurological changes, thereby increasing the risk of avoidable severe, permanent damage.2 Consequently, they often restrict PNB for tibia fractures, known to carry the highest risk for extremity ACS, and in many institutions the dictate, “we never block tibia fractures” governs practice. Dutton et al have previously commented on the need to balance the benefits of regional anesthesia while acknowledging “the risk of compartment syndrome in patients with extremity trauma is real, potentially serious, but relatively infrequent.”3 ACS appears to account for only 0.03% to 0.05% of all malpractice claims per year and is more likely to be litigated after elective surgery and in younger patients.4 The ongoing debate is largely argued in the halls of the operating rooms with opposing parties citing anecdotal clinical cases, expert opinion, and concerns about perceived medicolegal liability.
In this issue, Kakalecik et al from the University of Florida College of Medicine at Gainesville contribute a substantial data set to this evidence-sparse topic and challenge the long-standing assumption that PNB leads to a higher incidence of missed ACS.5 They report a single institutional retrospective review of 791 operative tibia fractures admitted from 2015 to 2022 and evaluate the relationship between perioperative PNB and the risk of missing an ACS after tibial surgery. They defined a potential missed ACS diagnosis as a persistent motor deficit 3-month postinjury and reviewed records to determine how many of these patients had perioperative PNB. With an institutional protocol to provide a low-concentration local anesthetic (0.2% ropivacaine) PNB to most patients with extremity fractures, a high percentage of operative tibia fracture patients received PNB (610/791). They identified 7 of 791 (0.9%) patients with a peroneal nerve motor palsy at 3 months, with 4 of the 610 (0.7%) in the PNB group versus 3 of 181 (1.7%) in the unblocked group. Moreover, within the PNB group, missed ACS occurred exclusively in patients who received a continuous PNB (n = 4), whereas no cases of missed ACS were found in patients who received only a single-shot PNB of limited duration. While their findings were not statistically significant, the failure to identify a higher rate of persistent neurologic deficit after a PNB was interpreted as support for their practice.
This article follows a recent publication from the same institution where Chembrovich et al reviewed a cohort of 26,537 patients admitted with long bone fractures from 2008 to 2018, including 12,979 tibial fractures.6 In this study, 87.5% of operative tibia and fibula fracture patients received PNB with the same low-concentration local anesthetic. Less than 0.2% of all tibia fractures (21 patients) had a diagnosed ACS during their hospital stay requiring a fasciotomy, and only 2 had a working PNB at the time of ACS diagnosis. Neither of those patients had permanent injury, while 3 patients suffered prolonged peroneal palsies in the non-PNB group. Based on their findings, they proposed “that better pain control with regional anesthesia may reduce the number of unnecessary fasciotomies in patients with poor pain tolerance, especially in situations where the decision made by the surgical team to operate is driven mainly by complaints of severe pain by the patient.” While both studies are retrospective and investigate a rare complication, their findings demonstrate support for provision of dilute local anesthetic PNB for patients requiring operative fixation. An alternative hypothesis, which was not assessed but noted by both, may be that providers identified the highest ACS risk patients and restricted PNB for them, thus reducing the overall incidence of ACS. Nonetheless, it is reasonable to conclude that a low volume, low concentration PNB, especially a single shot of limited duration, does not mask an early ACS nor contribute to a persistent nerve injury in patients with tibial fractures.
Of particular interest in the work by Kakalecik et al is their focus on “missed” ACS and the comparative incidence of this diagnosis in patients who received PNB versus those who did not.5 As the authors note, there is no accepted definition of a missed ACS within the orthopedic surgical community. As a surrogate, they chose to identify all motor deficits at the 3-month postinjury evaluation as a missed ACS, recognizing that the deficit identified may in fact have been preexisting, from the injury or surgical technique, and unrelated to an unrecognized ACS event. Thus, the actual incidence of missed ACS, better defined as a delayed or missed diagnosis of ACS with confirmatory clinical signs and symptoms, would be significantly less than the 0.9% identified in their study. Also, the observation that all the missed ACS in the PNB group occurred in patients with a perineural catheter might suggest avoidance of this technique due to concerns about continuous versus single-shot techniques. While this may be a reasonable assumption, there is an alternative explanation for this finding that was not evaluated. It is possible that the use of continuous techniques may reflect patient selection. Continuous analgesia is frequently used in patients with complex injuries requiring serial dressing changes or debridement—a population of patients that may be at higher risk for non-ACS-related nerve injuries. Not surprisingly, several recent reviews and regional anesthesia society and association statements advocate for modified PNB techniques in these patients but lack large studies to validate their position.7–14
Many regional anesthesiologists believe that when their surgical colleagues place a moratorium on PNB for tibial fractures, it denies many patients optimal care for several reasons. First, many fractures pose no clinically significant risk of ACS. For instance, a low-impact fracture in an elderly patient repaired via an open reduction and internal fixation with a plate should not be denied PNB due to the ACS risk associated with an intramedullary tibial nail in a young, muscular patient with a high-velocity traumatic injury.15 Second, even in patients at higher risk for ACS, PNB would not ostensibly delay or obscure the diagnosis of ACS. Currently, dynamic, intermittent intracompartmental pressure (ICP) measurements remain the gold standard for the diagnosis of ACS.16 Compared to clinical diagnosis with the classic findings of pain, paresthesia, poikilothermia, and paresis, ICP measurements have a greater sensitivity and specificity in the detection of ACS (89% and 90% vs 86% and 71%, respectively).17 With improvements in continuous ICP monitoring technology, it is likely these devices could allow for early ACS detection regardless of the analgesic intervention used. This would be valuable in patients with altered mental status due to traumatic brain injury or sedation/analgesia where reliance on clinical signs of disproportionate pain or new neurologic findings for an evolving ACS is not possible.16 More recently, noninvasive methods for ICP measurements have been introduced, but there remains a lack of demonstrated validity for their routine clinical usage.16
Most importantly, missed ACS is exceedingly rare in the era of ultrasound-guided regional anesthesia (UGRA). UGRA allows for risk-modifiable adjustments to single or multiple nerve blocks, such as reduced injection volumes and precise catheter placement for continuous PNB. Low-volume, short-acting local anesthetics can provide excellent analgesia for 1-3 hours, allowing for closed reductions and sometimes operative fixation, with monitoring for ACS symptoms after block cessation. Dilute concentrations of local anesthetic, frequently provided by pause-enabled continuous PNB catheters, maintain motor function and manage proportionate pain effectively, potentially avoiding unnecessary fasciotomies.6,18 Selective femoral nerve or adductor canal blocks may relieve a portion of the pain from a fractured tibial plateau osteotome without masking lower leg compartment syndrome, as these compartments are only innervated by branches of the sciatic nerve. Even if ACS ischemic pain is transmitted via nerves in the intimal layer of the popliteal or femoral artery, theoretically implicating a large volume nerve block in masking a lower leg ACS, UGRA techniques enable the administration of LA directly circumneural to the nerve with limited to no spread around the adjacent vessels.19 Lastly, if PNB is withheld, alternative treatments must be administered; and opioids, other systemic medications, and general anesthetics with airway intubation may pose a greater risk of impairing early ACS detection, along with the various side effects and morbidity associated with systemic medications.19
Even in a trauma-focused specialty hospital, such as ours, it is tough to change culture. However, discussions that engage trauma orthopedic leadership, institutional regional anesthesiology expertise, and bedside providers to review the abovementioned PNB technique modifications, risk of alternative analgesic options, institutional monitoring protocols, true ACS risk, and reference to these larger data sets should yield an expanded utilization of PNB in patients with tibia fractures.
Ultimately, orthopedic and anesthesiology departments must collaborate, assess institutional resources and limitations, ask pertinent questions, engage in multidisciplinary discussions, and devise evidence-based protocols. Topics of discussion should include:
- Can better categorization and improved monitoring protocols of those at increased risk of ACS allow for different treatment modalities?
- When are a patient’s subjective complaints relied on to assess for a developing ACS, and should patients unable to provide clinical feedback be offered different analgesic options? Is there a role for more objective ACS monitoring in your facility?
- How is a missed or late-diagnosed ACS defined? How is it determined whether or not it was masked by an analgesic intervention?
- How frequent are ACS assessments performed, and could low-volume short-acting local anesthetics wear off before the next assessment?
- Who performs the ACS assessments and how quickly can a patient with a developing ACS undergo a decompressive fasciotomy in your facility?
- If large-volume, dense, long-acting local anesthetics were avoided in this population, would there be any patient for whom a PNB would be contraindicated? Would there be any reason not to administer at least a low-volume femoral nerve or adductor canal block for tibial plateau fractures?
- Conversely, if short-acting PNB was provided, would patients experience more rebound pain that could be confused with new onset disproportionate pain and increase the suspicion of an impending ACS, with the need for decompressive fasciotomies?
- Will the same ACS risk be ironically increased with utilization of alternative analgesic modalities? With proper guidelines and a multidisciplinary approach, can ultrasound-guided low volume low concentration precision PNB finally be offered to patients without the exaggerated fear of medical liability?
Ideally, these questions should be proven by appropriately sized randomized trials that test the various hypotheses and guide evidence-based practice. In the interim, however, rational application of PNB utilizing low-volume low concentration local anesthetics appears to be a safe and reasonable approach for the management of patients with tibial fractures in the acute setting. The time is now to introduce sensible PNB in trauma patients with appropriate safeguards to detect and rapidly act on a developing ACS. Honest risk assessment should prevail over an all-inclusive “all-or-nothing” decision-making for the betterment of patient care.
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