Frost Technique H versus Technique V in Anesthetic Block of the First Toe: A Comparative Study.

Blackground This study aims to compare 2 methods of anesthetic block in the rst toe in patients with onychocryptosis. Methods A total of 70 ingrown toenails of the rst toe in 59 patients underwent a digital anesthetic block using the V technique, while 70 ingrown toenails of the rst toe in 57 patients underwent a digital anesthetic block using the H technique. As study variables, the effectiveness of the anesthetic block of the rst toe was evaluated at 10 and 20 minutes after each of the techniques. Results An of was and while technique H observed ecacy at and


Introduction
Onychiptostosis, or ingrown toenails, appear when the lateral edges of the nail penetrate the skin and cause in ammation and pain. If left untreated, they can become infected [1]. The most frequent cause is a bad nail cut, hereditary factors, biomechanical or structural alterations of the foot, hyperhidrosis and the inappropriate use of footwear [2].
In most cases, surgery is the most effective treatment, and there are different techniques [3,4], the phenolalcohol technique being the most speci c and studied [5,6].
These surgeries are performed under local anesthesia. Among the local anesthetic techniques, the trunk techniques are the most frequently used on the rst toe. This is innervated by four nerves that are located on both sides of the proximal phalanx and are distributed longitudinally: two nerves in the dorsal area (super cial peroneal nerve and deep peroneal nerve), and two nerves in the plantar area, which are future.
of the common plantar nerve [7].
The most commonly used trunk technique in the rst toe is the digital ring block or H-technique described by Frost in 1952 that requires two punctures [8] on each side of the proximal phalanx ( Figure 1). In some occasions, there are technical failures, which can cause an insu cient anesthetic effect and the possibility of rescue injections. This situation forces the clinician to multiple punctures controlled postoperative pain in the puncture area and an increase in the doses of injected anesthetic solution.
For this reason, it is necessary to know and manage other alternative techniques of anesthetic block of the rst nger.
One of the alternatives to technique H is technique V, described and published for the rst time in 2017. It is a little-known technique, which requires a greater learning curve, but allows anesthetic blockage of the rst toe with a single puncture. on the back of the rst toe and two lateralizations in the medial and lateral area of the metatarsophalangeal joint [9].

Materials And Methods
An experimental, multicenter, prospective, randomized study was carried out to compare the two anesthetic techniques, where the e cacy of the anesthetic block of the rst toe was evaluated 10 and 20 minutes after performing technique V and technique H. Patients with a history of sensitivity or allergy to local anesthetics in the amide, pregnancy or lactation group, neuropathy, cognitive de cit, and Raynaud's syndrome were excluded from the study. The allocation of patients in each group was done randomly, depending on the number of medical records.
The effect of the anesthetic block was evaluated at 10 and 20 minutes after performing one of the two techniques. The times to control the anesthetic effect were calculated based on the latency time of lidocaine, with 10 minutes to start the rst symptoms and 20 minutes to start the latency for complete anesthesia.
To verify the effect of the anesthetic block, the side of the nger pad was pressed with tweezers and the patient was asked if the nger felt anesthetized, lacked sensitivity, or had a lost pain sensation.
In patients who, 20 minutes after performing one of the techniques, did not have a su cient degree of anesthesia, the technique was reinforced with new punctures, as rescue.
In both techniques, a 5 ml dose of 2% lidocaine without epinephrine was administered with a conventional syringe and a 0.6 x 25 mm needle.
All the data were recorded in a table specially prepared for the present study.

Results
The nal sample of the study consisted of 140 onychocryptosis surgeries of 115 patients (52 men and 88 women) with a mean age of 40.93 years and a range of 12-90 years.
In 72 subjects, the ingrown toenail was found on the right foot, and in 68 subjects, the left foot. In patients with infection, 10 minutes after performing technique V, it was 39% effective, while it was 28% in technique H. The 20 minutes in technique V, the effectiveness was 70%, and technique H was 50%.

Discussion
In a patient requiring surgery to treat the ingrown toenail, an anesthetic blocking technique should be performed correctly so that the patient does not report pain during surgery [8,9,14].
In this study, 115 patients of both sexes had onychocryptosis and required an anesthetic block to partially or completely remove the nail from the rst toe.
Lidocaine is a local anesthetic agent with an amide structure, developed in 1943 by Swiss Nils Lofgren and his colleague Bengt Lundqvist [15]. Currently, it is the most widely used nesting type local anesthetic and is a benchmark for comparative studies with other anesthetics in the same group [10].
Lidocaine is characterized by a rapid onset, around 10 minutes, and a moderate duration of action of 1.5 hours [16,17]. It is metabolized mainly by the CYP3A4 enzyme in the liver into pharmacologically active metabolites [16] and is a suitable drug for in ltration, regional and super cial anesthesia [18].
Latency times vary according to the anesthetic technique to be used, this would be explained by the distance that the anesthetic solution must travel from the deposit site to reach the nerve trunk [18].
In this study, the allocation of one of the two techniques (technique V and technique H) was performed randomly according to the number of medical records.
Regarding the results, we can highlight that, although the two techniques did not prove to be signi cantly different, the V technique was effective in 85.7% of the patients at 20 minutes compared to 72.9% of the H technique in it. period of time This means that the V technique is better by 12.9%.
This study also seems to suggest that in infected onychocryptosis, technique V is 20% more effective than technique H. This could occur due to the location where the anesthetic is deposited in technique V, which, being further from the focus of infection [7], facilitates the action of the anesthetic drug [19].
One of the limitations of this study is the number of subjects. A sample size calculation (95% con dence level) was performed, in which a total of 126 subjects in each group are needed to obtain more conclusive results.

Conclusion
In conclusion, we can a rm that both methods of anesthetic block in the rst toe are safe and that the Vtechnique, with a single puncture, has a slightly higher effectiveness. Frost technique for anesthetic block of the rst toe with two puncture sites. Technique V for the anesthetic block of the rst toe with a single puncture