Clavipectoral fascia block associated with intermediate cervical plexus block versus intermediate cervical plexus block alone in clavicle surgeries: a randomized clinical trial

Abstract

Background

Midshaft clavicle fractures account for approximately 5% of all bone fractures and frequently require surgical fixation to restore shoulder function. Regional anesthesia techniques are commonly used to improve perioperative analgesia for these procedures; however, the optimal strategy for clavicle surgery remains uncertain. This randomized clinical trial aimed to evaluate whether adding a clavipectoral fascia plane block (CFPB) to an intermediate cervical plexus block (ICPB) improves immediate postoperative analgesia compared with ICPB alone.

Methods

In this prospective randomized double-blind trial, 40 adult patients undergoing surgical fixation of midshaft clavicle fractures under general anesthesia were randomly assigned to receive either ICPB combined with CFPB (intervention group) or ICPB alone (control group). All regional blocks were performed under ultrasound guidance using a 38-mm linear transducer. The primary outcome was morphine consumption in the post-anesthesia care unit (PACU). Secondary outcomes included PACU length of stay and perioperative adverse events. Data were analyzed using non-parametric methods, and effect sizes were estimated using Hodges–Lehmann median differences with 95% confidence intervals.

Results

Median (interquartile range) morphine consumption in the PACU was 0 (0–0) mg in the intervention group and 0 (0–3) mg in the control group (p = 0.149). The estimated median difference between groups was 0 mg (95% CI − 1 to 0 mg). Median PACU length of stay was 60 (60–82.5) minutes in the intervention group and 75 (60–90) minutes in the control group (p = 0.174), corresponding to an estimated median difference of − 10 min (95% CI − 25 to 5 min). No patients developed dyspnea, signs of Horner’s syndrome, or other complications related to the regional anesthesia techniques.

Conclusion

In this randomized clinical trial, the addition of a clavipectoral fascia plane block to an intermediate cervical plexus block was not associated with a statistically significant reduction in immediate postoperative morphine consumption or PACU length of stay. However, given the unexpectedly low opioid consumption and the resulting floor effect, modest differences between interventions cannot be excluded. Larger adequately powered studies are required to better define the role of combined regional anesthesia techniques in clavicle surgery.

Trial registration

The study was registered with the Brazilian Registry of Clinical Trials (ReBEC) under number U1111-1255-2364.

Introduction

Clavicle fractures are common orthopedic injuries, especially among young and active people, and account for about 5% of all bone fractures. Epidemiological studies estimate an incidence of 29 to 64 cases per 100,000 people each year, with nearly 70% of these fractures happening in the middle third of the clavicle, which is biomechanically vulnerable because of its shape and exposure to direct trauma [1]. Although many clavicle fractures can be treated without surgery, displaced or unstable fractures often need surgical fixation to restore proper alignment and shoulder function [2].

Over the past twenty years, the indications for surgical treatment of clavicle fractures have broadened, leading to a rise in operative procedures globally. This trend has been matched by increased interest in perioperative pain management strategies that enhance postoperative comfort while reducing opioid use and anesthesia-related risks. Additionally, the growing adoption of outpatient surgical pathways for clavicle fracture fixation highlights the need for effective regional anesthesia techniques that enable quick recovery and early discharge while providing adequate pain relief [3].

Despite these advances, the most effective regional anesthesia method for clavicle surgery remains debated. The primary challenge comes from the complex and not fully understood sensory innervation of the clavicle. Both the cervical and brachial plexuses are involved in clavicular innervation, leading to various proposed regional anesthesia techniques aimed at these neural pathways.

Tran et al. [4] highlighted the ongoing debate regarding clavicular innervation and emphasized the variability in anatomical descriptions reported in the literature. While there is general agreement that the skin overlying the clavicle is primarily innervated by the supraclavicular nerves arising from the cervical plexus, the sensory supply of the clavicle itself remains less clearly defined. Several neural structures, including the supraclavicular, subclavian, suprascapular, and long thoracic nerves, have been proposed as contributors to clavicular periosteal innervation.

More recent anatomical investigations have provided further insight into this issue. In a cadaveric study, Leurcharusmee et al. [5] demonstrated that the supraclavicular nerve is the principal sensory contributor to the middle third of the clavicle, although additional branches from the subclavian and lateral pectoral nerves may also participate in its innervation. These findings have important implications for the design of regional anesthesia techniques to provide effective analgesia for clavicle surgery.

Several regional anesthesia approaches have therefore been explored for clavicle procedures. General anesthesia combined with regional analgesia remains the most used strategy, particularly because patients are typically positioned in the beach-chair or semi–beach-chair position during surgery, requiring airway protection. Regional techniques that have been investigated include the superficial cervical plexus block, the interscalene brachial plexus block, and, more recently, the clavipectoral fascia plane block [6, 7]. However, no clear consensus currently exists regarding the optimal regional anesthesia technique for these procedures.

Although the interscalene brachial plexus block provides reliable analgesia, it is associated with potential adverse effects, including ipsilateral phrenic nerve blockade, transient upper-limb motor paralysis, Horner’s syndrome, and, rarely, nerve injury. These limitations have stimulated interest in more targeted regional techniques that focus specifically on the sensory innervation of the clavicle while minimizing motor blockade and respiratory complications.

The clavipectoral fascia plane block, first described by Valdés-Vilches [8], has emerged as a promising regional anesthesia technique for clavicle surgery. The clavipectoral fascia is a dense connective tissue layer located deep to the pectoralis major muscle that surrounds the clavicle and its periosteal nerve branches. Injection of local anesthetic within this fascial plane is thought to block terminal sensory branches supplying the clavicle.

Labandeyra et al. [9] further investigated this technique in a cadaveric model and demonstrated that local anesthetic injected within the clavipectoral fascial plane spreads predominantly over the anterosuperior surface of the clavicle. These findings suggest that the clavipectoral fascia block may provide effective analgesia for fractures involving the middle third of the clavicle, particularly when the periosteum is disrupted.

Another regional anesthesia technique that has gained attention in this context is the intermediate cervical plexus block, first described in 2004 [10]. This technique targets the interfascial space between the sternocleidomastoid muscle and the prevertebral fascia, allowing blockade of the supraclavicular nerves while potentially avoiding complications associated with deeper cervical plexus blocks. With the widespread use of ultrasound guidance, this block has become increasingly precise and safe, making it a promising option for procedures involving the head, neck, and clavicular region [11–13].

Given the anatomical complexity of clavicular innervation, combining the intermediate cervical plexus block with the clavipectoral fascia plane block could theoretically provide broader sensory coverage by simultaneously targeting both superficial cervical plexus–derived nerves and deeper periosteal branches surrounding the clavicle.

Therefore, the primary objective of this randomized clinical trial was to evaluate the quality of immediate postoperative analgesia, measured by morphine consumption in the post-anesthesia care unit (PACU), in patients undergoing surgical fixation of middle-third clavicle fractures. Specifically, the study compared the combination of clavipectoral fascia plane block and intermediate cervical plexus block with intermediate cervical plexus block alone. The secondary objective was to assess the duration of postoperative recovery in the PACU.

Methods

Study design and ethical approval

This prospective, randomized, double-blind clinical trial was conducted between August 2020 and November 2021 at Hospital Governador Celso Ramos, Brazil. The study protocol was approved by the Institutional Research Ethics Committee (approval number 4.365.270) and was conducted in accordance with the Declaration of Helsinki. The trial was registered with the Brazilian Registry of Clinical Trials (ReBEC; registration number U1111-1255-2364). All participants provided written informed consent prior to enrollment. The study followed the Consolidated Standards of Reporting Trials (CONSORT) guidelines for randomized clinical trials.

Participants

Inclusion criteria included patients aged 18 to 65 with an American Society of Anesthesiologists (ASA) physical status classification of I, II, or III and a body mass index (BMI) between 18 and 35 kg/m². Exclusion criteria included refusal to participate or sign the informed consent form, chronic opioid use, pre-existing neurological deficits, allergies to study medications, or signs of infection at the intervention site.

Patients with chronic opioid use and neurological deficits were excluded to minimize confounding factors that could affect postoperative pain perception or analgesic requirements. Although these criteria may limit the generalizability of the findings to some clinical populations, they were adopted to ensure a more homogeneous study sample and to allow clearer evaluation of the analgesic effects of the regional anesthesia techniques under investigation.

Randomization and blinding

Participants were randomly assigned in a 1:1 ratio to either the intervention (I) group (intermediate cervical plexus block combined with clavipectoral fascia plane block) or the control (C) group (intermediate cervical plexus block alone).

Randomization was performed using a computer-generated block randomization sequence (Randomizer.org). Allocation concealment was ensured using sealed, opaque, sequentially numbered envelopes that were opened only after patient enrollment.

Patients scheduled for outpatient surgical fixation of middle-third clavicle fractures were invited to participate. After receiving detailed information about the study protocol, including perioperative procedures, postoperative pain management, and the evaluation process, patients who provided informed consent were randomly assigned to either group I or group C, as previously described.

The investigator responsible for postoperative data collection and outcome assessment in the post-anesthesia care unit (PACU) was blinded to group allocation. Due to the nature of the procedures, the anesthesiologist performing the regional blocks could not be blinded. Patients remained unaware of the specific regional technique used.

Anesthesia protocol

All patients received standardized total intravenous general anesthesia. No premedication or preoperative analgesics were administered before induction of anesthesia to avoid confounding the assessment of postoperative analgesic outcomes.

Anesthesia was induced using target-controlled infusion (TCI) of propofol at an initial plasma concentration of 4 µg·mL⁻¹ and maintained at 3–4 µg·mL⁻¹. Remifentanil was administered as a continuous infusion at 0.1–0.2 µg·kg⁻¹·min⁻¹ according to clinical requirements.

Neuromuscular blockade was achieved with atracurium (0.5 mg·kg⁻¹) to facilitate endotracheal intubation.

After induction of anesthesia and prior to the regional anesthesia procedures, patients received adjunct medications including: dexamethasone 4 mg, ketoprofen 100 mg, dipyrone 1 g. No medium or long-acting opioids were administered intraoperatively.

Regional anesthesia techniques

All regional anesthesia procedures were performed after induction of general anesthesia using ultrasound guidance. A 38-mm linear ultrasound transducer (HFL38x, Sonosite FujiFilm^® M-Turbo) and a 22-gauge 50-mm short-beveled needle (Stimuplex A-50, B-Braun) were used. The ultrasound probe was covered with a sterile transparent dressing, and the skin was disinfected using 0.5% alcoholic chlorhexidine solution.

• Group I (Intervention): Patients received an intermediate cervical plexus block, as described by Tran et al. [4], under ultrasound guidance with 10 mL of 0.5% ropivacaine (Ropi^® Cristália Laboratory, Brazil), combined with a clavipectoral fascia block, as described by Valdés-Vilches [8], using 20 mL of 0.5% ropivacaine (10 mL at the medial-third/middle-third junction and 10 mL at the lateral-third/middle-third junction of the clavicle).

• Group C (Control): Patients received an intermediate cervical plexus block under ultrasound guidance with 10 mL of 0.5% ropivacaine.

Intermediate cervical plexus block procedure

The patient was positioned supine with a cervical rotation of 30 to 45 degrees toward the opposite side. The ultrasound transducer was placed transversely over the midpoint of the sternocleidomastoid muscle at the level of the cricoid cartilage. After identifying the sternocleidomastoid muscle and its posterior border, the interscalene groove between the anterior and middle scalene muscles was located. The cervical plexus was visualized superficially to the prevertebral fascia, and a 22 G short-beveled needle was inserted from lateral to medial, with its tip near the cervical plexus. After negative aspiration, 10 mL of 0.5% ropivacaine was injected.

Clavipectoral fascia block procedure

With the patient supine, the ultrasound transducer was placed over the medial-third/middle-third junction of the clavicle. After localizing the clavicle, 10 mL of 0.5% ropivacaine was injected adjacent to the clavicular periosteum. A similar procedure was performed at the lateral-third/middle-third junction.

Because the blocks were performed under general anesthesia to minimize patient discomfort, immediate clinical confirmation of block success was not possible.

Postoperative analgesia and outcome assessment

Upon arrival in the PACU, patients were assessed every 10 min for pain using a binary question (“pain present” or “pain absent”). If pain was reported, intravenous morphine (2 mg) was administered. Additional doses of 2 mg were given every 10 min as needed, up to a maximum of 20 mg. No pain reported was required for PACU discharge. The following outcomes were recorded: total morphine consumption in the PACU and duration of PACU stay.

Other perioperative data, including age, BMI, sex, comorbidities, and symptoms such as dyspnea or Horner’s syndrome, were recorded and monitored. Chest X-rays were performed if dyspnea was reported to investigate phrenic nerve paralysis.

Pain assessment was intentionally simplified to a binary outcome (“pain present” or “pain absent”) to reflect routine clinical decision-making in the PACU, where opioid administration is typically triggered by the presence of clinically relevant pain rather than graded pain scores. This pragmatic approach was chosen to standardize morphine administration and reduce inter-observer variability.

Statistical analysis and sample size calculation

The primary outcome was morphine consumption in the PACU.

Sample size calculation was based on detecting a 20% reduction in morphine consumption in the intervention group compared with the control group. This assumption was derived from previous studies evaluating postoperative opioid consumption after regional anesthesia for clavicle surgery and similar orthopedic procedures, as well as institutional clinical experience. Based on these data, morphine consumption in the control group was expected to be approximately 2–3 mg during the PACU stay. Assuming a two-sided alpha level of 0.05 and a statistical power of 80%, a minimum sample size of 19 patients per group was calculated. To compensate for potential losses or protocol deviations, 40 patients were enrolled.

Morphine consumption was selected as the primary outcome because it represents a clinically relevant measure of analgesic effectiveness and directly reflects the need for rescue opioid administration during the immediate postoperative period. Pain assessments in the PACU were performed using a binary approach (“pain present” or “pain absent”), reflecting routine clinical practice in the study institution.

Qualitative variables were reported as frequencies and percentages and compared using Fisher’s exact test.

Normality of continuous variables was assessed using the Shapiro–Wilk test. Because the distributions of the outcome variables did not meet the assumptions of normality, comparisons between groups were performed using the Mann–Whitney U test. Results were expressed as median (interquartile range [IQR]) for non-normally distributed variables and mean ± standard deviation for normally distributed variables.

Effect sizes were estimated using the Hodges–Lehmann median difference with corresponding 95% confidence intervals.

A p-value ≤ 0.05 was considered statistically significant.

All analyses were performed using SPSS for Windows version 20 (IBM Corp., Armonk, NY, USA).

Results

Participant flow and baseline characteristics

A total of 40 patients undergoing surgical fixation of midshaft clavicle fractures were enrolled and randomized. All randomized participants completed the study protocol and were included in the final analysis. The flow of participants through the study is summarized in the CONSORT diagram (Fig. 1).

Fig. 1.

Consort flow diagram

Baseline demographic and clinical characteristics were comparable between groups. Overall, 75% of participants were male and 25% were female, reflecting the typical epidemiology of clavicle fractures in trauma populations. There were no statistically significant differences between the intervention group (intermediate cervical plexus block combined with clavipectoral fascia plane block) and the control group (intermediate cervical plexus block alone) with respect to age, sex distribution, ASA physical status, or body mass index (Table 1).

Table 1.

Demographic data and physical status

Features	I	C	p
Sex* (M/F)	14(70%)/6 (30%)	16(80%)/4 (20%)	0.71
Age# (years)	32,60 ± 10,27	28,95 ± 10,61	0.28
BMI# (kg/m2)	25,55 ± 5,10	22,90 ± 3,17	0.056
ASA* I / II	11(55%)/9 (45%)	11(55%)/9 (45%)	1.0

M/F male, female, BMI body mass index, ASA American Society of Anesthesiologists

*frequency and respective percentages

^# mean ± dp

The intervention group had a slightly higher mean BMI compared to the control group (25.55 ± 5.10 kg/m² vs. 22.90 ± 3.17 kg/m² ; p = 0.056). No clinically perioperative differences related to BMI were observed during the study.

Primary outcome: morphine consumption in the PACU

The median (interquartile range [IQR]) morphine consumption during the PACU stay was 0 (0–0) mg in the intervention group, compared with 0 (0–3) mg in the control group (Mann–Whitney U test, p = 0.149) (Table 2).

Table 2.

Morphine consumption in mg and length of stay in PACU

	I	C	p
Morphine consumption (mg)	0 (0–0) *	0 (0–3) *	p = 0.149
Time in PACU (min)	60(60–82,5)*	75(60–90)*	p = 0.174

* median (IQR)

The Hodges–Lehmann estimate of the median difference between groups was 0 mg (95% confidence interval [CI]: −1 to 0 mg).

Secondary outcome: PACU length of stay

The median (IQR) PACU length of stay was: 60 (60–82.5) minutes in the intervention group; and 75 (60–90) minutes in the control group. The difference between groups did not reach statistical significance (p = 0.174) (Table 2).

Adverse events

No patients reported dyspnea or exhibited clinical signs of Horner’s syndrome during the postoperative observation period. In addition, no complications related to the regional anesthesia procedures were identified.

Although the absence of adverse events is reassuring, it should be interpreted with caution given the study’s relatively small sample size.

Discussion

In this randomized clinical trial, the addition of a clavipectoral fascia plane block to an intermediate cervical plexus block was not associated with a statistically significant reduction in immediate postoperative morphine consumption or PACU length of stay. However, morphine requirements were substantially lower than anticipated, with most patients requiring no rescue opioid during PACU stay. This marked floor effect limited the discriminatory capacity of the primary outcome and, together with other methodological limitations, precludes definitive conclusions regarding the comparative analgesic effectiveness of the two regional anesthesia strategies.

One possible explanation for the absence of a detectable difference between groups relates to the contribution of the cervical plexus to clavicular innervation. The supraclavicular nerves arising from the cervical plexus are widely considered the principal sensory supply to the skin and superficial structures of the clavicular region. Tran et al. highlighted the ongoing debate regarding clavicular innervation and the potential contribution of cervical plexus–derived pathways to clavicular nociception [4]. Blockade of these nerves may therefore have contributed to the low postoperative opioid requirements observed in both groups. Nevertheless, given the unexpectedly low morphine consumption and the resulting floor effect, the present findings do not permit definitive conclusions regarding the relative contribution of cervical plexus blockade or the potential incremental benefit of adding a clavipectoral fascia plane block.

The rationale for combining the intermediate cervical plexus block with the clavipectoral fascia plane block stems from the anatomical complexity and variability of clavicular innervation. Cadaveric investigations have suggested that, in addition to the supraclavicular nerves, neural contributions from the subclavian and lateral pectoral nerves, as well as other proposed neural pathways, may contribute to clavicular periosteal innervation [4, 5]. The clavipectoral fascia plane block has therefore been proposed as a technique capable of targeting terminal sensory branches adjacent to the clavicle. From a theoretical perspective, combining the two blocks could broaden sensory coverage by targeting both cervical plexus–derived innervation and deeper periosteal neural contributions.

The absence of a detectable incremental benefit from the clavipectoral fascia plane block in the present trial should, however, be interpreted cautiously. Leurcharusmee et al. demonstrated in a cadaveric investigation that the supraclavicular nerve is an important sensory contributor to the middle third of the clavicle, while additional contributions from other neural structures may also occur [5]. This anatomical variability provides a plausible rationale for both cervical plexus–based and more peripheral fascial plane approaches. The present results cannot determine whether the lack of a detectable between-group difference reflects a limited incremental contribution of the clavipectoral fascia plane block, insufficient sensitivity of the primary outcome, variability in block success or local anesthetic spread, or a combination of these factors.

Previous clinical studies have also investigated cervical plexus–based approaches for clavicle surgery. Abdelghany et al. reported comparable perioperative analgesic outcomes with superficial cervical plexus block alone and with combinations of superficial cervical plexus and brachial plexus blocks [6]. Ultrasound-guided cervical plexus blocks have also been used to provide analgesia for clavicular fractures in emergency care settings [12]. These findings support the relevance of cervical plexus–derived sensory pathways as an analgesic target, but they do not establish that cervical plexus blockade alone is sufficient for all patients or surgical conditions.

Conversely, more recent studies have reported promising results with the clavipectoral fascia plane block. Zhuo et al., in a randomized trial comparing a combined clavipectoral fascia plane block and cervical plexus block with an interscalene brachial plexus block, reported effective analgesia with the more peripheral approach and a lower incidence of diaphragmatic paralysis [7]. These findings suggest that the clavipectoral fascia plane block may have a role in regional anesthesia strategies designed to avoid brachial plexus–related motor and respiratory effects. However, differences in comparator interventions, local anesthetic techniques, outcome assessment, and study populations limit direct comparison with the present trial.

The local anesthetic volumes used in the present study should also be considered when interpreting the findings. The intermediate cervical plexus block was performed with 10 mL of 0.5% ropivacaine, whereas the clavipectoral fascia plane block involved a total of 20 mL of 0.5% ropivacaine divided between injections at the medial–middle and lateral–middle junctions of the clavicle. These volumes were selected according to the block techniques adopted for the study and were intended to provide local anesthetic distribution across the targeted anatomical regions. However, the optimal volume and distribution of local anesthetic for these techniques have not been definitively established. Because block success was not assessed clinically and local anesthetic spread was not formally quantified, the study cannot determine whether the selected volumes consistently produced the intended neural coverage. Variability in fascial anatomy and injectate spread may therefore have influenced the observed outcomes.

Several limitations should be considered when interpreting the present findings. Most importantly, morphine consumption was substantially lower than anticipated during study planning, with most patients requiring no rescue opioid during PACU stay. This resulted in a marked floor effect that reduced the ability of the primary outcome to discriminate between treatment groups and may have limited the study’s capacity to detect modest but clinically meaningful differences. The original sample size assumptions were therefore not representative of the observed outcome distribution, and the possibility of a type II error cannot be excluded.

Second, pain assessment was based on a binary outcome (“pain present” or “pain absent”) rather than a validated continuous scale such as the numeric rating scale (NRS) or visual analog scale (VAS). Although this approach reflected the clinical analgesic protocol used in the PACU, it provided limited sensitivity for detecting differences in pain intensity. Furthermore, because the same binary assessment directly determined whether rescue morphine was administered, the pain assessment and primary outcome were intrinsically coupled, introducing potential measurement coupling bias. The study therefore could not characterize pain intensity trajectories, time to first analgesic request, or more subtle differences in analgesic efficacy between groups.

Third, because the regional blocks were performed under general anesthesia, sensory testing could not be performed before surgery. Consequently, successful blockade of the intended neural targets could not be clinically confirmed in either group. Although all procedures were performed under ultrasound guidance using standardized techniques, variability in needle position, local anesthetic deposition, fascial anatomy, and injectate spread may have influenced block effectiveness. This limitation is particularly relevant when interpreting a trial comparing regional techniques, because an undetected incomplete or failed block could reduce the apparent difference between interventions.

Fourth, the trial was registered retrospectively on August 25, 2020, after enrollment of the first participants had begun. Participant recruitment and data collection were conducted from August 2020 to November 2021. Although registration occurred early in the study period, the fact that it followed the initiation of enrollment represents a limitation in reporting transparency, as the study objectives and outcomes were not publicly documented in a trial registry before recruitment began. This retrospective registration therefore limits independent verification of prospective outcome specification and should be considered when interpreting the study.

Fifth, postoperative analgesia was evaluated only during the immediate PACU period. Regional anesthesia techniques may have clinically relevant effects beyond the first 60–90 min after surgery, and the present study did not assess subsequent pain intensity, time to first analgesic request after PACU discharge, cumulative opioid consumption, rebound pain, or other longer-term analgesic outcomes. Therefore, the findings are restricted to the immediate postoperative period and cannot determine whether differences between the techniques might emerge later.

Additional methodological considerations should also be acknowledged. Although randomization was used to allocate participants, residual imbalance and confounding may persist in relatively small randomized trials. Furthermore, the study did not include a control group receiving general anesthesia without regional blockade, and therefore it cannot quantify the absolute analgesic contribution of either regional anesthesia strategy. The interpretation of PACU length of stay should also be approached cautiously because this outcome may be influenced by several non-analgesic factors, including postoperative nausea and vomiting, hemodynamic stability, institutional discharge criteria, staffing patterns, and workflow-related factors. PACU length of stay should therefore be regarded as a pragmatic recovery outcome rather than a specific measure of analgesic efficacy. Longer-term outcomes, including postoperative pain trajectories, opioid consumption beyond the PACU, functional recovery, and patient-reported satisfaction, were also not evaluated.

Despite these limitations, the present study contributes to the evolving evidence regarding regional anesthesia strategies for clavicle surgery [14, 15] and highlights several methodological considerations relevant to future trials. No statistically significant incremental benefit of adding the clavipectoral fascia plane block was demonstrated under the conditions evaluated. However, the unexpectedly low opioid requirements, limited sensitivity of the pain assessment method, inability to confirm block success, and restricted observation period substantially limit the strength of any comparative inference. Accordingly, the absence of a detectable difference should not be interpreted as evidence of equivalence between the interventions or as evidence that one regional technique is sufficient in all patients undergoing clavicle surgery.

Future trials should be prospectively registered and adequately powered using outcome assumptions appropriate to contemporary multimodal analgesic practice. They should incorporate validated pain intensity scales, time-to-event analgesic outcomes, cumulative opioid consumption over a longer postoperative period, and standardized confirmation of block success. Further anatomical and imaging studies evaluating the distribution of local anesthetic within the clavipectoral fascial plane and the relationship between injectate spread, volume, and clinical analgesia may also help refine the technical performance and indications of this block.

In summary, the addition of a clavipectoral fascia plane block to an intermediate cervical plexus block was not associated with a statistically significant reduction in immediate postoperative morphine consumption or PACU length of stay in this randomized clinical trial. However, the marked floor effect in opioid consumption, limited sensitivity and coupling of the pain assessment strategy to rescue morphine administration, absence of sensory confirmation of block success, and other methodological limitations constrain interpretation of these findings. The present results should therefore not be interpreted as evidence of equivalence between the two regional anesthesia approaches. Rather, a clinically meaningful incremental benefit of the clavipectoral fascia plane block could not be demonstrated under the conditions of this study. Larger, prospectively registered and adequately powered trials incorporating validated pain measures, confirmation of block success, and extended postoperative follow-up are required to better define the comparative effectiveness of these regional anesthesia strategies.

Authors’ contributions

D.C . contributed with conception and design of the work, first version of the manuscript.P.H. contributed with design of the work, revison of the manuscript.J.G. contributed with design of the work, analysis and interpretation of data and revisioin of the manuscript.J.V. contributed with analysis and interpretation of data and revision of manuscript.

Funding

There was no specific funding allocated for this study.

Data availability

The datasets used and analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

The study received prior approval from the Institutional Research Ethics Committee at Hospital Governador Celso Ramos, with approval number 4.365.270. Additionally, all participants provided signed informed consent.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.