Effect of Phenol Application Time in the Treatment of Onychocryptosis: A Randomized Double-Blind Clinical Trial

Background: In the treatment of Onychocryptosis, chemical matricectomy with 88% phenol solution is one of the most common surgical procedures due to a recurrence rate of less than 5%, but it may produce a delay in healing time. The objective was to compare the healing time between phenol applications of 30 or 60 s. Methods: A comparative, prospective, parallel, randomized, and blinded clinical trial was registered with the European Clinical Trials Database. Twenty-seven patients (54 feet) with 108 affected nail folds were randomized and treated with chemical matricectomy with phenol. Each hallux was randomly assigned to one of two groups (60 vs. 30 s phenolization). Each patient and one investigator were blinded to the phenol application time in each foot. The outcome measurements were healing time, recurrence, pain, post-surgical bleeding, inflammation, and infection rate. Results: The 30 s application presents a shorter healing time (14.93 ± 2.81 days vs. 22.07 ± 3.16 days; p < 0.001) with a similar recurrence rate (p = 0.99). Post-operatory bleeding, pain, inflammation, and the infection rate did not show significant differences (p > 0.05). Conclusions: The 30 s phenol application time offers a shorter healing time than 60 s without affecting the effectiveness of the procedure, showing the same rate of complications.