Ultrasound-guided regional anaesthesia in foot and ankle surgery

Abstract

The use of regional anaesthesia in foot and ankle surgery is becoming well recognised, particularly in patients who prefer to stay awake during the procedure and for better post-operative analgesia. Its use is ideal for patients with multiple co-morbidities, in whom general anaesthesia (GA) otherwise would could be challenging. The procedures performed with landmark/anatomical guidance alone carry a relatively higher risk of complications, risk of inadvertant injection into the intarvascualr space leadinf to local anaesthetic toxicity, the majority of which complications are caused by incorrect placement of the needle. Hence, ultrasound guidance is frequently used to minimise those risks.

Although various regional anaesthetic techniques for foot and ankle surgery have been described, their comprehensive review is lacking. This manuscript aims to fulfil this void. The focus will be on the peripheral methods of regional anaesthesia including the plexus and single nerve blocks. Various techniques with their benefits and potential complications will be discussed. In addition, the evidence on the efficacy of an ultrasound-guided approach as well as its cost implications will be explored. There are significant considerations in deciding whether to implement this technique in routine clinical practice and this review aims to summarise the available literature to establish the evidence base behind it.

1. Introduction

The use of regional anaesthesia in foot and ankle surgery offers significant advantages over its alternatives. In comparison to the systemic delivery of analgesia, patients with regional anaesthesia have been found to have a shorter length of hospital stay, reduced pain scores, lower opioid requirements, quicker recovery^1,2 and essentially greater patient satisfaction.³ Furthermore, it provides an alternative for patients in whom GA would be challenging and avoids complications associated with them. Although there is some evidence to suggest that regional anaesthesia lowers post-operative complications compared to GA, the reports are conflicting with regards to differences in the post-operative morbidity and mortality.4, 5, 6, 7

The development of regional anaesthesia began with the discovery of cocaine by Friedrich Gaedecke and Albert Niemann in 1859 ⁸. This finding initiated a chain of events that radically improved its surgical anaesthetic potential. Early research into the substance had found that it suppressed fatigue and was also beneficial in treating morphine addiction. However, it was not until 1884 that Carl Koller, an Austrian ophthalmologist, uncovered its anaesthetic properties in ophthalmological surgery.⁹ This revelation inspired the invention of regional anaesthesia techniques, still used in surgery today. Shortly after the discovery, William Halsted used cocaine to perform the first brachial plexus block.¹⁰ It was then used in 1898 by August Bier as a spinal anaesthetic.¹¹ However, the use of cocaine became undesirable due to its toxic and addictive effects. Therefore, research into the alternatives began. Bier described the technique of intravenous regional anaesthesia using one such alternative, procaine. He described local anaesthetic being injected intravenously between two tourniquets.¹² The essence of this technique is still used, however only one tourniquet is usually used and the anaesthetic is injected into the extremity’s venous system. The first account of the, now very routine, continuous nerve block was in 1946 by Ansbro. He described performing a supraclavicular nerve block using a needle passed through a cork, which provided stability.¹³ Despite the availability of advanced equipment and technology, the principles of regional anaesthesia have not changed much from the past. These form the basis of the current anaesthetic practice, with subsequent advances occurring in the approach and agents used. For regional anaesthesia, anaesthetic agents are injected in close proximity to the nerves of interest so as to produce sensory blockade of the surgical field. In order to do this, these nerves must be localised. A blind approach can be used, which exploits anatomical landmarks to locate the nerve. However, more robust methods utilising ultrasound and nerve stimulation techniques are preferred. The technique of ultrasound guided regional anaesthesia was first described in 1978 by La Grange et al.

A Doppler ultrasound was used to visualise blood flow whilst performing supraclavicular brachial plexus block.¹⁴ Subsequent advancements in the ultrasound technology have improved the visualisation potential. Peripheral nerves and important surrounding structures such as blood vessels and muscles can be identified. The needle tip and the flow of an anaesthetic agent can be seen, potentially allowing for appropriate needle insertion and release of the local anaesthetic (LA). However, the ability to exploit full potential of an ultrasound depends heavily on the individual’s proficiency with the technology.

2. Methods

We conducted a search for ‘ultrasound guided regional anaesthesia/nerve block in foot and ankle surgery’ through databases: AMED (Ovid), BNI (Ovid) CINAHL (EBSCO), pubmed, google scholar, Embase (Ovid) and Medline (Ovid) for publications between 2007 and 2020 in English language only. We ran further searches to include key words ‘technique’, ‘efficacy’, ‘safety’, ‘complications’ and ‘cost’. The papers and studies were analysed from this search and the relevant evidence (only considering level I and level II evidence for analysis) was categorised to form this review. Case reports, small case series and articles not directly related to ultrasound guided regional anaesthesia (UGRA) in foot and ankle surgery, were excluded.

This manuscript outlines the current opinion for UGRA in foot and ankle surgery based on these publications. In particular, their specific conclusions on risks, benefits, patient outcomes, cost implications of various techniques, different areas used for the nerve block and type of anaesthetic agents used are discussed in detail. Every attempt has been made to provide answers to the most common issues faced by the orthopaedic surgeons and anaesthetists in their day-to-day practice.

3. Discussion

3.1. Techniques

A number of studies comparing different techniques to provide adequate UGRA and analgesia for foot and ankle surgery have been compared and analysed.

3.2. Injection/infiltration technique

The speed of onset, duration and success of a nerve block can be influenced by many factors including site of infiltration relative to the nerve; the plane relative to the nerve or the probe and the depth of penetration/distance to the nerve. In this section we focus on the studies comparing different infiltration techniques.

Tammam et al. compared different ultrasound techniques when infiltrating the sciatic nerve at the infra-gluteal region in 120 patients undergoing foot surgery.¹⁵ By comparing short or long axis views of the nerve with in-plane or out-of-plane needle insertion, they were able to form four groups for direct comparison. The authors concluded that the patients who received blocks using long axis view with in-plane insertion of the needle had the highest levels of comfort as well as the shortest performance time.

Madsen et al. similarly found a significant positive association between longitudinal neural exposure to local anaesthetic and nerve block duration in a similar study in which they evaluated.

Common peroneal nerve block in 180 healthy volunteers.¹⁶

Brull et al. concluded that circumferential injection of the local anaesthetic around the sciatic nerve at the popliteal fossa could improve the rate of sensory block without an increase in the procedure time for the block or block-related complications compared to a single-location injection technique.¹⁷ Morau et al. also found that circumferential distribution of LA for popliteal sciatic nerve block was associated with a fast surgical block.¹⁸

Choquet et al. compared circumferential extra-neural spread to sub-paraneural (also including unintentional intra-epineural spread) in 90 patients having a tibial nerve block.¹⁹ They concluded that the unintentional intra-epineural had the fastest time of onset followed by the sub-perineural injection which had the longest duration.

Fig. 1a, Fig. 1b, Fig. 2a, Fig. 2b demonstrate ultrasound guided infiltration of the femoral nerve and the popliteal nerve respectively.

Fig. 1a.

Femoral nerve block (anatomy).

Fig. 1b.

Shows anaesthetic needle and infiltration of local anaesthetic.

Fig. 2a.

Anatomy of the popliteal nerve.

Fig. 2b.

Local anaesthetic infiltration of the popliteal nerve.

3.3. Guidance techniques

A number of methods have been described to locate the nerve for anaesthetic infiltration. The studies that met our selection criteria and have compared these different methods i.e. ultrasound guided, anatomical landmark guidance or nerve stimulation are discussed below.

The largest of these studies was undertaken by Chin et al. who compared outcomes in 655 patients receiving ankle nerve blocks through anatomical landmark guidance or ultrasound guidance over a period of six years.²⁰ Their results demonstrated that the ultrasound-guided technique had far better clinical efficacy as compared to the anatomical technique, especially when the practitioner was not very experienced.

Bendtsen et al. also demonstrated the superiority of UGRA compared to the nerve stimulation guidance in a study of 100 patients who underwent elective operative interventions.²¹ The ultrasound guidance used for sciatic catheter placement improved the success rate of sensory block, reduced the number of needle passes, increased patient satisfaction during catheter placement and reduced morphine consumption.

A direct comparison between ultrasound-guided and nerve stimulation blocks was undertaken by Ponde et al. The authors analysed the results of 60 sciatic and femoral nerve blocks performed for paediatric patients with arthrogryposis multiplex congenita and the ultrasound guidance was shown to significantly increase the success rate of the blocks.²²

3.4. Areas and location

Common nerve blocks performed in order to achieve the anaesthesia of the foot and ankle for operative interventions include blocks of the saphenous nerve, sciatic (popliteal) nerve, tibial nerve and common peroneal nerve.

In 2010, Protic et al. conducted a small randomised control trial involving 40 patients who suffered bi-malleolar fractures and underwent operative fixation under either ultrasound guided femoro-popliteal block (US-FPB) or spinal anaesthesia (SA).²³ The group of patients from the US-FPB group achieved significantly longer postoperative analgesia while the SA group had a faster onset of anaesthesia.

Perlas et al. randomised 89 patients to receive either a single injection of LA at the site of bifurcation of the sciatic nerve through a common para-neural sheath or through two separate circumferential injections of the tibial and common peroneal nerves distal to the bifurcation.²⁴ The injection at the site of the bifurcation resulted in a 30% quicker onset time of both sensory and motor block and required only a single needle pass thus respecting the integrity of the epineurium and intra-neural structures. This study is supported by the study by Morau et al. which concluded that blocking the nerve at its separation into two components was associated with a faster block time.¹⁸

Prasad et al. studied 50 elective foot or ankle surgery patients who were randomly allocated to receive the ultrasound-guided sciatic nerve blocks either 5 cm proximal or 3 cm distal to the bifurcation at the popliteal fossa.²⁵ While the patients in the both groups developed a complete blockade in both the tibial and common peroneal nerve distributions, the onset time was reduced by 30% in those patients who received the distal placed blocks compared to the more proximal placement.

Buys et al. reported findings similar to that of Perlas et al. and Prasad et al. The authors also compared the time of onset of anaesthesia between ultrasound-guided blocks performed separately at the tibial and common peroneal nerves (infiltrating at the popliteal fossa) against the pre-bifurcation sciatic block. They also found that the patients in the tibial-peroneal group (blocks performed separately) had significantly faster onset of anaesthesia (19.2 compared to 26.1 min).²⁶

Borglum et al. compared the use of single penetration dual-injection (SPEDI) block for the sciatic and saphenous nerve in the proximal thigh (at the level of the lesser trochanter) to the single injection infiltration of the popliteal-sciatic and saphenous nerves separately.²⁷ Although the results for efficacy of the both techniques were equal, SPEDI was faster, required one skin penetration and obviated the need of repositioning of the leg during the procedure. The authors, therefore, recommended the SPEDI block for trauma patients.

3.5. Agents

There are numerous variables not only in the agent used but also in their concentration and volume. Although, this allows for greater choice for the operator, it also increases the variability in current practice.

In a randomised controlled trial, Techasuk et al. concluded that the mean effective volume of combined lidocaine 1%, bupivacaine 0.25% with epinephrine 5 mg/ml for use in ultrasound-guided sub-paraneural popliteal sciatic nerve block is 13.3 ml (95% confidence interval, 10.2–16.4 ml).²⁸

Fredrickson et al. compared the analgesic effects of low-volume ultrasound-guided ankle block with conventional volume (surface landmark) technique.²⁹

In 72 patients, who underwent elective foot or ankle surgery under GA, they found that the low-volume ultrasound-guided ankle block had a high success rate. The reduced local anaesthetic volume, however, marginally compromised the postoperative analgesia during the first 24 h.

Cappelleri et al. investigated the effect of LA dilution on the onset time and duration of double-injection sciatic nerve block.³⁰ The authors failed to find evidence supporting the belief that varying volume and concentration (whilst maintaining a fixed total dose) of mepivacaine had any effect on the onset time or duration of the anaesthesia.

In 1978, La Grange et al. reported the use of ultrasound as an adjunct to performing peripheral nerve blockade and since then multiple studies have reviewed the efficacy of ultrasound guided regional anaesthesia in relation to different nerve blocks.

In 2008, Perlas et al. compared the efficacy of ultrasound guided sciatic nerve block performed at the popliteal fossa with a single injection peripheral nerve stimulator guided block with either a tibial or peroneal endpoint.³¹ This randomised control trial concluded that the anaesthesia utilising the ultrasound guidance had a higher block success rate (p = 0.005) and a significantly lower motor-sensory score at each assessment time. Bendtsen et al. also compared ultrasound guided catheter placement to nerve stimulated catheter placement.²¹ 100 patients were randomised into two groups. The ultrasound guidance group had a higher success rate of continuous sciatic nerve sensory blockade (94% compared to 79% p = 0.03), lower morphine consumption and fewer needle passes suggesting higher efficacy with ultrasound guidance.

A retrospective cohort study of 655 patients by Chin et al. compared an ultrasound guided ankle block (527 patients) to an anatomic landmark guided (ALG) technique (128 patients).³² The authors concluded successful anaesthesia was more likely with the ultrasound-guided technique (p = 0.001), those with ALG were twice as likely to receive unplanned general anaesthetic (p = 0.001) and anaesthetic supplementation (p = 0.04). The ultrasound group also perceived less post-operative pain (33% compared to 43%, p = 0.049). However, 56 patients were excluded from the study as technique could not be determined.

Abrahams et al. conducted a meta-analysis to find out if there was any advantage of using ultrasound over other methods of nerve localisation. The eight studies that focused on the lower extremity were too heterogeneous to allow a valid review. The sciatic nerve blocks were assessed by four prospective randomised studies 1,6,7,8. Three out of these four studies demonstrated a quicker onset complete sensory block at the sciatic nerve with ultrasound guidance 6,7,8 over other techniques.³²

4. Conclusion

Overall, there is some evidence suggesting that ultrasound guided technique improves block success rates, has a faster block progression, without an increase in procedure time. However, it was noted that supporting studies were performed using different types of block utilising differing types of anaesthetic agents. The operator bias, therefore, cannot be ruled out in these studies.

Declaration of competing interest

None.