Wound Healing and Infection in Nail Matrix Phenolization Wounds

Abstract

After nail matrix ablation using phenolization, a medicated wound dressing (10% povidone iodine), an amorphous hydrogel dressing (Intrasite Gel), and a control dressing (paraffin gauze) were evaluated. Forty-two participants, randomly divided into three dressing groups, were evaluated. Healing time did not differ between the 10% povidone iodine (33 days), amorphous hydrogel (33 days), and the control dressing (34 days). For all groups, the clinical infection rate was lower than in previous studies, and there was no clinical difference between groups (one infection in the povidone iodine and control groups; none in the amorphous hydrogel group). However, in the amorphous hydrogel group, other complications, such as hypergranulation, were more likely. This investigation indicated that medicated or hydrogel dressings did not enhance the rate of healing or decrease infection rates. (J Am Podiatr Med Assoc 91(5): 230-233, 2001)

Phenolization matrix ablation is one of the most commonly practiced and successful nail avulsion techniques used to treat ingrown and symptomatic involuted nails.[1-4] The procedure is simple, has few postoperative symptoms, and has been reported to have a higher success rate than surgical excision.[5, 6] However, while phenolization matrix ablation has notable advantages, concerns have been expressed over the delayed healing time associated with it[3, 7] and the increased rate of clinical infection.[3]

The delay in healing rates after phenolization matrix ablation is thought to be associated with the chemical burn from the phenol. Therefore, while patient outcomes, such as regrowth rates and amount of pain, may be better after phenolization matrix ablation than with surgical excision, healing times have been reported to vary from 26 days[2] up to 49 days,[8] significantly longer than reported with surgical excision.[2, 4, 5]

To minimize possible complications associated with the increased healing time, a variety of wound care agents have been advocated. Medicated dressings, particularly povidone iodine, were highly recommended in the 1980s for the reduction of infection rates.[3, 8] However, recent developments suggest that povidone iodine may, in fact, interfere with tissue proliferation and wound healing.[9-12] Furthermore, there has been a move to adopt recently developed principles in the area of wound management[13] that support the use of moist wound agents to manage postoperative nail avulsion wounds.[2, 14] The amorphous hydrogels are a commonly used moist wound dressing.

This investigation compared the effects of three commonly used wound dressings (povidone iodine, an amorphous hydrogel, and nonmedicated paraffin gauze) on nail ablation wounds after surgery.

Methods

Participants

Forty-two healthy participants who were to undergo a partial nail avulsion of the hallux were recruited from two outpatient clinics in Melbourne, Australia, during a 6-month period. Participants were selected after a thorough screening process in which lower-limb circulation and relevant health and medication issues were assessed (Table 1). Participants gave full informed consent for this study, as endorsed by the La Trobe University Human Ethics Committee, Melbourne, Australia.

Table 1. Exclusion Criteria

Table 1. Exclusion Criteria

The surgical procedure was performed by means of a standard protocol and full aseptic technique, based on that described by Foley and Allen.[2] Prior to surgery, participants were randomly allocated to one of three dressing groups: the povidone-iodine 10% (Betadine, Fauldings, Adelaide, Australia) with paraffin gauze; the amorphous hydrogel (Intrasite Gel, Smith and Nephew, Hull, United Kingdom) with paraffin gauze; and a control dressing of paraffin gauze.

Re-dressing Protocol

All participants returned for regulated, standardized dressing changes. Participants were seen approximately 48 hours after the surgical procedure for an initial dressing change and then every second day for 10 days. After this initial period, re-dressings were conducted every fourth day. During the 4-day dressing regimen, at least two clinicians were available to evaluate the wound for evidence of clinical infection (Table 2) and healing. All dressings were performed by means of a standard aseptic technique that included careful removal of the dressing, irrigation of the site with sterile saline, surgical debridement of the area if required, and re-dressing of the wound. Participants were withdrawn from the study whenever infection or other complications were noted.

Table 2. Operational Definitions

Table 2. Operational Definitions

Criteria for Healing

To limit subjectivity in the assessment of wound healing, criteria for a healed wound were developed (Table 2). When participants presented for re-dressing, two clinicians experienced in wound care assessed the wound independently. For the wound to be considered healed, both clinicians had to independently agree that all of the criteria were met. The healing time was the interval between the application of the first dressing (ie, at the time of surgery) and the day the wound was judged to be completely healed.

Results

The participant profiles for the three dressing groups are presented in Table 3. Six subjects were removed from the study owing to complications: hypergranulation tissue and infection. The four subjects who experienced hypergranulation tissue were from the amorphous hydrogel group. Of the remaining two infection complications, one was from the povidone iodine group and the other from the control group.

Average time to healing is presented in Table 3 by group. An analysis of healing time indicated that for participants who experienced no complications, there was no difference in the time to healing between the 10% povidone iodine (mean healing time, 33.4 days), amorphous hydrogel (33.3 days), and the control dressing (34.2 days; F = .086, P < .918).

Table 3. Summary of Group Characteristics

Table 3. Summary of Group Characteristics

Discussion

Time to healing for the post-phenolization ablation wound in this study compares favorably to previously reported healing times of 49 to 54 days14 and 35 days.[2] The results of this study indicated that there was no difference in time to healing for the post-phenolization nail ablation wounds with the addition of an antimicrobial agent (the povidone iodine) or an amorphous hydrogel in the uncomplicated wounds.

However, before generalizations are made to the wider population, it must be acknowledged that even with the small numbers in each group, the power for this study is 90% (β = .10). With low power, it is common for nonsignificant results to be found. However, this power calculation indicates that there is only a 10% chance of not finding a significant result when one actually exists and is considered to be acceptable.[15-18] Furthermore, the logistics of repeating this study with an increased sample size would not be recommended without appropriate financial resources.

The occurrence of infection in only 2 of 42 participants was a better rate than has been reported in previous literature.[8, 14] This may be because this study used a clinical definition of infection and required frequent changes of dressing. Rinaldi et al[3] identify extremely high wound-site infection rates: up to 87.5%. As a result, both Dagnell[8] and Rinaldi et al strongly recommend the use of prophylactic antimicrobial agents; both studies define the need for these on the basis of wound swabs. In the current study, which uses a clinical definition of infection, only a small infection rate was noted. A positive microbial swab at a post-phenolized wound site might, in fact, be indicative of the flora present at most wound sites. As such, it might not progress to a clinical infection and therefore might not be a good predictor of clinical infection. However, given the decreased infection rates in this study, it is important to note that the results suggest that clinical infection rates did not increase without the use of a prophylactic antimicrobial agent.

When these findings are applied to the clinical situation, it is important to acknowledge the influence of a strictly controlled research protocol and the ways in which that might vary from the clinical experience. The researchers applied all dressings in a strictly controlled antiseptic manner and performed sharp debridement of superfluous tissue whenever it was deemed necessary for any participant. While these protocols were necessary to eliminate factors that might influence the effect of the dressings, they do not represent common clinical practice and may have contributed to the decrease in both the infection and healing rates.

An unexpected and particularly interesting finding from the research was reported in the amorphous hydrogel dressing group. Four of the 16 participants developed acute hypergranulation tissue and had to be withdrawn from the research for ethical reasons once they reached day 55. In fact, when the events that were likely to result in withdrawal from the study (infection and hypergranulation tissue development) were considered, the members of the amorphous hydrogel group were four times more likely (odds ratio is equal to 4.33) to demonstrate complications. Furthermore, it is important to note that all subjects with complications were omitted from the statistical analysis.

Conclusion

Dressing choice for the post-phenolization matrix ablation wound has been driven by the desire to increase the healing rate and reduce potential complications. However, while the literature has reported the use of various medicated dressings and forms of amorphous hydrogels, there has been no conclusive evidence to support the use of either. The medications used in this study had no effect on reducing the healing rate, although frequent surgical debridement and stringently controlled aseptic re-dressings may have helped to improve the time to healing in comparison with previous research.