Performing surgical procedures on the hand with WALANT has become increasingly popular, as it allows for safe surgery without the need for a tourniquet and sedation of the patient through the combination of lidocaine and epinephrine [32], and this review aimed to determine whether the WALANT technique would be an advantageous alternative for surgical procedures on thumb injuries, compared to conventional anaesthesia, in terms of pain parameters and patient function.

In general, WALANT showed pain levels similar to those of LA, while GA showed greater pain. In terms of function and satisfaction, the differences were not statistically significant, but patient anxiety was lower with WALANT.

Of the three articles that analysed pain, there was no uniformity in the results, which may be a consequence of the type of injury and surgical protocol, while one of the studies analysed De Quervain's syndrome, the others dealt with rhizarthrosis, and surgery for osteoarthritis of the CMT is a more complex procedure, which can involve deep tissue dissection, bone removal and the placement or not of a component and consequently be more painful regardless of anaesthesia [33]. Despite these figures, some studies report that WALANT is an advantage because it allows the patient to actively move and perform the thumb dyad during a MCT suspensionoplasty, allowing adequate tension to be confirmed [34]. With regard to pain at the time of injection being more painful than the tourniquet, this may be due to the insertion of the needle, which causes sudden, sharp pain, regardless of the solution injected [29].

As with pain, the functional results of this review do not provide sufficient data to demonstrate the advantage of WALANT, some variables (joint ranges and muscle strength) are directly related to the clinical severity of the patient, the selection of the surgical technique and the different rehabilitation protocols [35]. On the other hand, the scales and tests used to assess function are different in the studies included. With regard to the Quick-DASH questionnaire, Dacombe et al. [36]. showed that DASH has an excellent reliability profile, but it addresses the upper limb as a functional unit, which makes it debatable whether it is the most suitable for thumb injuries or more specific hand injuries. Even so, it has been found that in the first phase WALANT provides an ideal opportunity for Total Active Motion in the intraoperative period [31]. With the patient awake, it is possible to assess the movement of the thumb at the time of surgery and provide the appropriate tension under the active movement of the thumb via WALANT [37]. According to the literature, WALANT in other hand injuries allows surgeons to initiate early mobilisation and the possibility of a hand therapist taking part in the surgery to teach range-of-motion exercises and discuss rehabilitation plans [32], making it a benefit for the patient's function. Just as Lalonde [38] considers it important for the patient to first practice the permitted movements in a completely pain-free environment during surgery and under the direction of a therapist, Moriya et al. [39] also states that it is better to recover as much active range of motion as possible through early active movement than to wait for an improvement with tenolysis. These arguments are in line with the results obtained in this research, in which WALANT leads to a reduction in adhesions in the flexor tendons and consequently fewer occurrences of tenolysis [30, 31].

In terms of anxiety, the results obtained with WALANT coincide with studies that have analysed other hand injuries using this technique, such as the study by Davison et al. [40] in which anxiety was also lower. These data correlate with several factors, one of which is the lack of need for preoperative tests, another is the lack of need for intraoperative monitoring and also the patient's perception of side effects; with WALANT, patients simply leave the surgery and go home [41]. On the other hand, the study by Abd Hamid et al. [42] reported no statistically significant difference between the WALANT and GA groups, in which anxiety was assessed with the Amsterdam Preoperative Anxiety and Information Scale (APAIS). The differences in results may be related to the use of different scales to assess the same variable.

In terms of satisfaction, the results of this review do not differ between WALANT and the other anaesthetics, unlike the study by Seretis et al. [43] in which they obtained a very high satisfaction rate, especially in the WALANT group, as well as the study by Ayhan et al. [44] in which 77.5% of the patients admitted that surgery with WALANT was easier than they had expected. This disagreement in results may be related to the age of the patients, as in the articles on thumb osteoarthritis with WALANT the sample had a higher average age. The literature mentions that the older population is more likely to suffer from post-traumatic stress and anxiety, which can be exacerbated in hospital environments, while anxiety can increase the perception of pain and decrease patient satisfaction [45].

With regard to operating theatre times, while on the one hand the WALANT group reported slightly longer operative times compared to LA due to preoperative preparation, on the other hand they reported that patient time in the operating theatre was shorter and that patients were discharged more quickly compared to GA [28]. The disparity in the values found is due to the waiting time of between 26 and 30 min for the administration of the WALANT injection, as opposed to the 7 min traditionally taught. The vasoconstrictor effect of epinephrine has to act against the vasodilator effect of lidocaine and the release of histamine from the trauma of the needle and the fluid injected for haemostasis during surgery [46]. Regarding patient discharge, this is quicker with WALANT because there are no effects of deep sedation as with GA (nausea, vomiting and dizziness) and hospitalisation is considerably reduced [35].

In the studies that were included, the complications of WALANT or other anaesthetics, as well as the different concentrations of epinephrine that were administered, were not taken into account, which is one of the limitations of this review. Another limitation was the choice of study design (only RCTs), although useful in terms of conceptualisation, study design can cause variability in results. Of the studies that used WALANT in their approach [15], described surgical techniques and procedures, eight did not use comparison scales and eight were case studies, as this is an emerging technique, there seems to be a lack of evidence on the subject or the studies have not yet been completed. It is essential to carry out more in-depth research, with more reliability and evidence, as well as the need to use appropriate function scales. The articles included came from different countries, with different age groups and pathologies, as well as surgical approaches, so the lack of specific target populations and poorly defined comparators (heterogeneity of results) also meant that a meta-analysis was not possible.

Each stage of this systematic review followed a protocol, giving this study a greater degree of confidence. The question was defined in terms of population, interventions, comparators, results and study design (PICOS), which meets a topical issue, becoming the strengths of this study.

In the future, it would be worth considering carrying out studies that address a functional assessment before and after surgery, relating WALANT to the rehabilitation protocol and even determining the benefits of including a therapist specialised in hand rehabilitation in the team. The implementation of this technique by the hand surgery team is considered important for successful recovery, due to the interaction between hand surgeons, therapists and patients. This could be one of the most significant changes in an operating theatre, as those who have had the opportunity to be involved in this intraoperative communication highlight this relationship as a next step in the development of hand surgery.