A comparison of electrosurgery and sharp debridement in the treatment of chronic neurovascular, neurofibrous and hard corns. A pragmatic randomised controlled trial
Article Outline
- Abstract
- 1. Introduction
- 2. Method
- 3. Results
- 4. Discussion
- 5. Conclusions
- Conflict of interest statement
- Acknowledgments
- References
- Copyright
Abstract
A randomised controlled trial was undertaken to compare treatment outcomes for neurovascular, neurofibrous and hard corns. Patients with suitable lesions were referred from community clinics within Manchester PCT. Fifty-nine subjects were enrolled into the study and randomised to one of two treatment groups; group (a) those treated with electrosurgery and (b) a control group treated with standard sharp debridement. The principle outcome measure was the Visual Analogue Scale (VAS) pain score (0, no pain; 10, worst pain experienced) and lesions were categorised as demonstrating no change, partial or complete resolution. Data were analysed using ‘Intention to Treat’ methodology, i.e. analysis of data from subjects randomised to each group (electrosurgery group n
=34; control group n=25). The results show a statistically significant reduction in pain in group (a) as reported at the 6 month review (p=0.0001) with a complete and partial resolution rate of 26% and 50%, respectively compared with group (b) whose pain level reduction was not significant and which showed resolution rates of 4% and 28% only.
Keywords: Podiatry, Chiropody, Corns, Neurovascular corns, Electrosurgery, Sharp debridement, Visual Analogue Scale, Intention to Treat analysis
1. Introduction
Hard corns (heloma durum), defined as localised areas of thickened epithelial stratum corneum containing a nucleus of keratin, frequently develop at sites of increased or abnormal forces (notably intermittent compressive stresses and friction) acting on the skin. Long-standing corns can be complicated with the invasion of nerve fibres and blood vessels (neurovascular corns) and can become dense and fibrous (neurofibrous corns) causing considerable pain which has a significant effect on the activities of daily living of the patient. In practice it may be difficult to distinguish between different categories or types of lesion but because of the pain involved, they are difficult and unrewarding to treat and often require a high frequency of treatment [1]. The problems caused by such lesions have been experienced by a proportion of the podiatric patient population in Manchester. It was found by the research team that, in the majority of the subjects referred to the study by podiatrists, the treatment most frequently received by patients with these lesions was scalpel debridement, augmented in a proportion of cases with an orthosis. However, it was reported that treatment was frequently unsatisfactory as removal of sufficient tissue was impossible because of the pain involved [2]. The lesions were also found to be generally unresponsive to treatment with orthoses. It is likely that there are a variety of reasons for this; for example, inappropriate footwear or the orthosis may have been unsuitable, poorly prescribed, fabricated or fitted, i.e. not modifying the excessive stresses on the tissues occurring at the site of the lesions; such stresses being the most likely primary aetiological factor in their development, prolongation and deterioration.
Prior to undertaking the study, patients were being referred for electrosurgery. The lesions treated were generally of long-standing, many of very long duration, which had been resistant to conservative treatments and which required frequent visits to the clinic. The electrosurgery was generally well received but without formal evidence reports of improved treatment successes and the associated enhanced patient well-being would remain anecdotal. It was decided therefore to undertake a research study to evaluate the technique in which a null hypothesis could be tested in order to demonstrate effectiveness and improved patient outcomes.
Electrosurgery in a variety of forms (desiccation, fulguration, coagulation) has been used in a range of medical (dermatology, plastic surgery, gynaecology, proctology, urology) and other specialisms for many years. The ‘Hyfrecator’ is widely used in this context in the treatment of cutaneous conditions and allows precise destruction of superficial and deep tissues [3]. The technique has been adopted for the treatment of painful plantar corns and verrucae [4], [5], [6], [7], [8], but it appears that its use has been somewhat limited and, although there are some reports of successful outcomes there remains a lack of evidence in the literature for its efficacy. In addition, there are concerns that the procedure may in itself cause problems although there seems to be little evidence to support this notion.
The process of electrosurgery, i.e. electrodesiccation, provides a means by which pathological tissue can be removed by the application of a dense electrical current via a small handheld electrode which is applied to the lesion. The heat generated by the passage of a current desiccates the tissue, which adopts a blanched appearance thus allowing its separation and removal [4], [5]. Normally the lesion can be lifted away with little requirement for ‘excision’ or ‘debridement’ and frequently this can be achieved with little or no resulting haemorrhage. Clearly, when using electrosurgical techniques, it is important to minimise trauma and damage to tissues surrounding and deep to the lesion. If necessary, should any bleeding occur, ‘fulguration’ (where a suitable electrode is held a short distance away from the tissue to produce sparking between the electrode and the surface) can be used as a haemostat. The effect on tissue is more superficial with fulguration than is the case with desiccation where the electrode is in contact with the tissue.
The electrical circuit from the Hyfrecator via the hand-piece probe to the lesion is completed by means of a dispersive plate placed under the fleshy part of the patient's leg. The plate, being relatively large in comparison to the electrode, ensures that no heat is generated at this part of the circuit. For safety reasons it is always advisable to use the dispersive plate as electrical current will always find the path of least resistance to ground to complete the circuit. This could be via the patient's hand or bony prominence if it were touching a metal component of the couch or treatment trolley or unit, resulting in discomfort or even a burn depending on the power setting used which should always be the minimum necessary for the procedure [4].
Electrosurgery is always carried out under local anaesthesia of the operative site [4], [6], [7], plantar areas normally requiring a tibial nerve block as a minimum. Depending on the location of the corn, other nerve blocks or additional local infiltration are required in order to obtain full anaesthesia of the area around the lesion.
2. Method
The North West Region R&D Support Unit based at Salford University provided help with the study methods, sample sizes, a power calculation based upon preliminary work and the randomisation procedure. Ethical approval was obtained prior to commencement of the study.
Suitable subjects with intractable helomatous lesions were recruited from patients attending for routine podiatry treatment at clinics and health centres across the city of Manchester and referred to the two centres at which the study was to take place. It was made clear to potential subjects by the referring podiatrist that referrals were for participation in a research study and not for electrosurgery treatment per se.
The study details were explained fully to each patient before referral and again before consent was obtained. In particular it was explained that the type of treatment to be received as part of the study (active intervention with electrosurgery or standard treatment) would depend upon the randomising process and this would not be known until after consent had been given and the process initiated. All subjects were therefore given sufficient time to make an informed decision as to whether or not they wished to participate in the research. Those who consented to take part in the study were included and, after consent had been obtained, the study administrative officer was telephoned with a request to consult the randomisation protocol and to open the next sealed envelope in sequence in order to ascertain the group – (a) electrosurgery or (b) control in which the subject would be included. Clearly with this type of study it is impossible to blind either subject or clinician to the type of intervention. Notwithstanding the information given at the time of referral, some patients refused to be enrolled for randomisation because they wanted to be guaranteed electrosurgery. Generally this was because their lesions were so painful and disruptive to daily activities that any chance of improved treatment was immediately attractive and requested; appropriate treatment was undertaken.
The Visual Analogue Pain Scale (VAS) was used as the main primary outcome measure. The scale consists of a 10cm line on which ‘0’ indicates no pain and ‘10’ indicates maximum pain severity. The patient is instructed to indicate and mark the line at a point between the two extremes, which would indicate and represent the highest level of pain experienced from the lesion. The scale is a commonly used method for the evaluation of the experience of pain, it is easy to use, results are reproducible, it can be used in a variety of settings, is sensitive to treatment effects and data derived from it can be analysed with standard statistical techniques [11]. Sample sizes of 21 per group were required in order to be sure of detecting a statistically significant difference of 3 points (30mm) on the VAS scale. A baseline score was recorded prior to treatment, subjects were followed-up at intervals with the score at the 6 month review used for analysis. This post-intervention review period was deemed appropriate – firstly it is an accepted trial review interval and further, it was a convenient interval for patients some of whom were likely to be drawn from the large transient population of Manchester which naturally forms a proportion of patients seen in the podiatry department. Presenting lesions were defined (as either hard, neurovascular or neurofibrous corns) by the participating podiatrist, categorical allocation being dependent upon the appearance of the lesion and findings during treatment. The size of lesions was not recorded.
In the planning stages of the study, advice from a statistician suggested that pain data derived from the VAS scale can be skewed and that non-parametric tests should be used for analysis. However, it is reported that parametric ‘t’ tests for two groups of subjects (and ANOVA tests for three and more groups) even without data transformations to bring the distributions closer to the normal distribution are good tests to find differences in VAS measurements among groups [10], [11]. With the sample sizes being relatively small, no assumption of normal distributions could be made; a Mann–Whitney test was therefore used for analysis and reporting of data with a significance level previously set at 0.05. Data were analysed utilising the ‘Intention to Treat’ (ITT) principle [12], [13]. At final review lesions were categorised in terms of outcome as being totally resolved – i.e. absence of lesion; partial resolution – defined as presence of lesion with improved symptoms or unresolved – those lesions that displayed unchanged symptoms. Patients were allowed unrestricted access to their podiatry clinics based on their clinical need for dressings (the first post-operative dressing was undertaken by the research team) and treatment during the follow-up period. The objective of the study therefore was to compare electrosurgery with a standard form of treatment with the null hypothesis to be tested being that there would be no difference in treatment outcomes.
Fig. 1, Fig. 2, Fig. 3, Fig. 4 show the ‘Conmed®’ equipment used in the study and the techniques employed.
Fig. 1.
The Hyfrecator: Conmed® Hyfrecator 2000 (Conmed Corp. 310 Broad St, Utica, NY 13501).
Fig. 2.
Application of electric current via probe on skin surface.
Fig. 3.
Removal of lesion following separation of tissue.
Fig. 4.
Appearance of operative site following removal of lesion.
2.1. Inclusion criteria
Diagnosis of chronic, long-standing painful hard, neurovascular or neurofibrous corns requiring frequent treatment (once per month or more).
Registered with the podiatry department for a minimum of 12 months prior to inclusion in the study.
Able to comply with the study, treatment and follow-up instructions.
Informed consent.
2.2. Exclusion criteria
Conditions that may lead to impaired tissue healing.
Metal implants or prosthetic joints between the emitting electrode and the dispersive circuit plate (electrosurgery group).
Cardiac pacemaker (electrosurgery group).
Contraindications to local anaesthetics (electrosurgery group).
Lack of informed consent.
Non-compliance with study protocol.
Under 18 years of age.
Those with learning difficulties, severely/mentally ill patients and any other vulnerable groups.
Pregnant women.
3. Results
Fifty-nine patients were recruited for the study and, although 5 subjects were lost to final follow-up, all randomised subjects were included in the ‘Intention to Treat’ statistical analysis. They comprised 34 subjects in the electrosurgery group and 25 in the control group. The characteristics of the study samples are shown in Table 1. Although some patients were treated for multiple lesions, data from one lesion only per subject was included in the analysis. Data presented in Table 2 show a significant difference in the pre- and post-intervention VAS scores in the electrosurgery group (p=0.0001) whilst the change in pain perception in the control group was not significant (p=0.12). A comparison of the incidence of lesion resolution in the two groups is given in Table 3 whilst Table 4 shows further analysis of outcomes based on lesion type. Table 5 presents a summary of results for each location at which corns were treated in subjects comprising the electrosurgery group.
Table 1. Characteristics of study sample.
| Study sample characteristics | |
|---|---|
| Subjects (lost to follow-up) | 59 (5) |
| Age [mean (SD)] years | 50 (13.5) |
| Males | 35 |
| Subject ethnicity (%) | |
| Caucasian | 68 |
| Afro-Caribbean | 17 |
| South Asian | 15 |
| Lesion type [electrosurgery (control)] | |
| Hard corn | 11 (15) |
| Neuro fibrous corn | 12 (5) |
| Neurovascular corn | 8 (3) |
| Lesion site [electrosurgery (control)] | |
| Calcaneus | 5 (1) |
| Plantar metatarsal head area | 25 (19) |
| Digital | 1 (3) |
| Lesion duration (mean SD) months | |
| Electrosurgery | 103.1 (92.5) |
| Control | 85.7(102.8) |
Table 2. Analysis of visual analogue scores for study groups.
| Visual Analogue Scale Scores, group comparison | |||
|---|---|---|---|
| VAS 1 | VAS 2 | p value | |
| Group | |||
| Electrosurgery | 74.9 (19.2) | 37.3 (31.1) | 0.0001 |
| Control | 60.4 (23.8) | 46.0 (28.1) | 0.12 (ns) |
Table 3. Lesion resolution frequency.
| Group comparison, lesion resolution | ||||
|---|---|---|---|---|
| Partially resolved | Totally resolved | Unresolved | Lost | |
| Group | ||||
| Electrosurgery | 17 (50) | 9 (26) | 5 (15) | 3 (9) |
| Control | 7 (28) | 1 (4) | 15 (60) | 2 (8) |
Table 4. Group comparison: outcome based on lesion type.
| Group comparison, resolution by lesion type | ||||||
|---|---|---|---|---|---|---|
| Electrosurgery group | Control group | |||||
| HDa | HNFb | HNVc | HDa | HNFb | HNVc | |
| Lesion | ||||||
| Outcome | ||||||
| Partially resolved | 7 | 5 | 5 | 4 | 3 | 0 |
| Totally resolved | 2 | 4 | 3 | 1 | 0 | 0 |
| Unresolved | 2 | 3 | 0 | 10 | 2 | 3 |
aHD, hard corn. |
bHNF, neurofibrous corn. |
cHNV, neurovascular corn. |
Table 5. Electrosurgery group: treatment outcomes by lesion site.
| Electrosurgery group, resolution by lesion site | ||||||||
|---|---|---|---|---|---|---|---|---|
| Site | ||||||||
| Calc | PD1 | PMA1 | PMA2 | PMA3 | PMA4 | PMA5 | Total number | |
| Resolution | ||||||||
| Partial | 1 (20) | 1 (100) | 0 | 2 (50) | 4 (40) | 4 (80) | 5 (100) | 17 |
| Total | 3 (60) | 0 | 0 | 1 (25) | 4 (40) | 1 (20) | 0 | 9 |
| Unresolved | 1 (20) | 0 | 1 (100) | 1 (25) | 2 (20) | 0 | 0 | 5 |
4. Discussion
In research trials, randomisation of subjects to intervention and control groups is undertaken in order to minimise bias in treatment effects. In situations where there are protocol violations, e.g. where some subjects have not adhered to the allocated management strategy and those subjects are excluded from the analysis (i.e. analysis by treatment administered – also known as explanatory or per protocol analysis) such analysis can be flawed and may influence the unbiased comparison which was afforded by the randomisation process. Methods by which missing data can be handled usually depend upon assumptions of outcomes though these are likely to lead to spurious results. It is suggested that ‘Intention to Treat’ (ITT) analysis avoids the problems created by omitting dropouts and other non-concordant subjects which may, if not included in the analysis, negate randomisation and lead to an overestimation in clinical effectiveness. This however is a complex and controversial field and the appropriate analysis to be employed for a particular study is likely to depend on the precise research question to be investigated and the type of study and data to be analysed [12], [13], [14], [15], [16], [17]. Interested readers should consult appropriate texts for a full discussion on the subject.
In this study, subjects in the electrosurgery group (a) which were lost to follow-up and therefore unable to furnish data for analysis were assumed to have had no change to the baseline VAS score whilst those in the control group (b) were assumed to have the best possible outcome of 0 pain at final review. Treating data in this way reduces the difference in treatment effects between the groups and provides the most rigorous of possible outcomes from the study for statistical analysis and therefore produces a conservative estimate of the treatment effect [12]. The use of both ITT and per protocol statistical analysis gave similar results in that electrosurgery group had significantly lower pain levels from the lesions treated (or, where the lesion was fully resolved, the lesion site) post-operatively than did the control group subjects given standard scalpel debridement. The reduction in pain demonstrated using the visual analogue scale and shown statistically (Table 2) is likely to be the result of the more effective removal of helomatous tissue and associated neurological components than is possible with normal sharp debridement. In practice, after administration of the local anaesthetic and prior to application of the electrosurgical probe, the lesion is debrided to remove as much of the pathological tissue as possible to facilitate application of electrical current and allow finer judgement of the extent of desiccation produced in order to limit potential damage to healthy tissue beneath and adjacent to the lesion. Clearly, such debridement with the benefit of local analgesia will be considerably more effective than standard debridement without anaesthetic but nonetheless electrosurgery enables still further tissue removal.
The primary study outcome measure together with the incidence of total and partial resolution of lesions in the electrosurgery group (shown in Table 3), suggest that electrosurgery can be effective in the treatment of chronic helomatous lesions. These findings are similar to the results of other studies [5], [6] in that the rate of improvement, i.e. the proportion of subjects in the electrosurgery group showing partial and total resolution, was high at 76% (50% and 26%, respectively) whereas in the control group only 32% of subjects demonstrated similar levels of resolution. The anomalous finding that one lesion (4%) in the control group given standard treatment demonstrated complete resolution could be due to a variety of factors ranging from treatment being provided by a different practitioner using different techniques and, for example, changes in lifestyle and working patterns of the individual. These were not investigated.
The classification of each lesion was determined at the time of treatment and the frequency and level of resolution by lesion type is given in Table 4. The best outcomes in the study would appear to have been achieved (in the electrosurgery group) with neurovascular corns with 3 from 8 (38%) being totally resolved with the remaining 5 (62%) partially resolved with no lesions unresolved. For hard corns comparable data are 18% and 64% with 2 (18%) lesions unresolved and for fibrous lesions 33%, 42% and 3 (25%), respectively. For the electrosurgery group, Table 5 shows the distribution and frequency of the three levels of resolution at each of the locations where lesions were found. It can be seen that lesions occurred most frequently under the third metatarsal head area where total and partial resolution rates were both 40% but 20% remained unresolved. At the 4th metatarsal head area, heel and 2nd metatarsal complete and partial resolution rates together were 100%, 80% and 75%, respectively. All five lesions at the 5th metatarsal area and the one lesion occurring under the hallux showed partial resolution. However, the small size of the study renders such analysis of little value in forming conclusions from these data.
It should be borne in mind that there can be risks in the use of electrosurgery and the cause of the lesion should be determined. The technique may not be appropriate and if an underlying bony or soft tissue abnormality is suspected, this should be addressed by referral to the patient's GP for suitable investigations and onward referral or further assessment by a podiatric or orthopaedic surgeon. There is the possibility of inadvertent tissue damage and the resultant ulceration from the procedure always requires appropriate follow-up and treatment. The potential for scar formation exists, but as in a case referred to this study, tissue damage had already occurred with scarring from previous surgical attempts to remove a corn. There have been no reports of a patient's condition worsening after electrosurgical treatment in the small number of cases where there was no improvement in the condition. Patients should be made aware that a degree of post-operative discomfort is normal for a period of time as healing progresses.
A further consideration in the use of electrosurgery is that the heating of tissues to high temperatures can cause smoke/steam to be released and these could contain viral particles or other pathogenic substances. To reduce the tendency for vapour formation the electrodessication probe and tissues undergoing treatment should be well moistened with saline to improve electrical conductivity. Alternatively, it could be suggested that the high temperatures generated form a sterile field, though in the treatment of verrucae in particular it could be advisable to use a form of vapour extraction to reduce any inherent risks.
It has been found in electrosurgery practice that at the dermo-epidermal junction there was often a deep invagination into the dermis beneath the location of the nucleus of the lesion and this required additional application current from the electrode in order for it to be fully removed. The use of a pointed probe just touching the tissue caused it to adhere to the probe allowing the material to be pulled away leaving the deeper cavity in the dermis. A haemorrhage often resulted (this could have been from prominent vascular elements which had extended into the lesion) which was then fulgurated if necessary, however the formation of the blood clot could have assisted in the healing process. Whether this deeper area, with its increased surface area of stratum germinativum could be the cause of a hyperkeratotic lesion at the location when subjected to compressive and/or other stresses or is an effect of a lesion's presence is open to speculation.
The requirement for local anaesthetic and the development of a knowledge and skills base in order to use electrosurgery should be no barrier to using the technique in cases where it is deemed appropriate for recalcitrant lesions [4].
It was found that some patients referred to the study refused consent to participate because of the (50%) possibility of continuing with standard treatment. Such patients were treated with electrosurgery immediately. All subjects included in the control group were given the opportunity to have electrosurgery treatment on completion of the study.
5. Conclusions
As the group sample sizes in this study were small, the results should be interpreted in that context and larger clinical trials would be useful in verifying these results. However, the outcomes of the study are broadly in line with those of previous research and suggest that the use of electrosurgical techniques can provide an improved treatment modality for long-standing and painful hard, fibrous and neurovascular corns which have not responded to other forms of treatment. The efficacy of electrosurgery relies on its ability to facilitate the removal a greater depth and volume of helomatous tissue without pain. Although beyond the scope of this study, it is likely that correctly prescribed, fabricated and fitted orthoses which modify foot function and/or plantar force distribution would augment this form of treatment and improve longer-term outcomes. Further research and investigation is necessary in order to better understand the effects, benefits and risks of electrosurgery and indeed the qualities and effectiveness of function and force modifying orthoses.
Conflict of interest statement
It has been determined that in undertaking this study there have been no conflicts of interest for any author, contributor or participant.
Acknowledgments
The authors would like to thank the following people for their assistance and participation.
Ramzana Anwar, Rachel Hills, Steve Sanderson and Steve Boag for their help in study design, recruitment and treatment of subjects and patients and data collection. Steve Barrow, Statistician, North West Region R&D Support Unit, University of Salford, for statistical advice and the randomisation method.
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PII: S0958-2592(10)00004-0
doi:10.1016/j.foot.2010.03.003
© 2010 Elsevier Ltd. All rights reserved.
