Ulcers in patients with leprosy can remain for several years after the initial infection is resolved and can result in large economic and social losses. Such losses were observed in this study, which was primarily composed of former patients that have lived with their ulcers for many years. The most important causal factor for neuropathic foot ulcers is the presence of a dynamic or static deformity leading to local areas of peak pressure on insensitive skin, which has been well illustrated by pressure studies . This repetitive overload on specific areas of the sole could partially explain why plantar ulcers are deeper and smaller than leg and ankle ulcers. Almost half of the evaluated subjects in this study did not use any kind of adapted footwear, suggesting some negligence by the patients in the prevention of disabilities and self-care procedures. The free distribution of special footwear doesn't ensure its adequate utilization. Health care workers need to be constantly pushed to establish a patient continuum education process about self-care routines and to improve the techniques currently employed to encourage the use of preventive tools. Low adherence to such programs and self-care procedures is a concern of countries that still bear a significant leprosy burden.
In the present study, patient ulcers were predominantly chronic wounds, which could have interfered with LLLT success. Fibroblasts in chronic wounds have impaired responsiveness to growth hormone, which may be due to an increased number of senescent cells . It was observed in neuropathic diabetic foot ulcers that wound duration negatively affected the chance of healing after 12 weeks of proper wound care . A high prevalence of vasomotor reflex impairment attributed to autonomic nerve lesions has been observed in newly diagnosed patients with leprosy . Lepromatous patients exhibit a tendency to develop chronic leg ulcers, which are partially caused by a single vascular disturbance during M. leprae infection and/or by peripheral neuropathy . These alterations may explain the notable occurrence of chronic leg and ankle ulcers in this sample, especially in subjects who were hypertensive or over 40 years old. One study of 124 patients with leg wounds of different etiologies identified that 54% of them were hypertensive . It is necessary to give special attention to the control of high blood pressure, as this comorbidity was common in our study and has the potential to negatively affect the wound healing process in patients with leprosy. The follow-up period of 12 weeks is longer than some previous studies [8, 17–19], but was chosen because it is enough time for the wound healing process to complete [20–22].
Rest is a common recommendation as a strategy of self-care, but it was not adopted by the majority of patients. Such behavior combined with the non-use of adapted footwear (though use was advised by the health care staff) could have interfered with the results, as the plantar ulcers remained under mechanic stress during daily living activities and walking. The fact that researchers were not blind in the study and therefore knew which group subjects were receiving laser therapy or routine treatment could have led to a possible bias, but the photographic register of all treated ulcers allows confirmation of collected and analyzed data.
There was no formally sample size calculation, but we included all subjects attended at dressing service of UREMC that met the inclusion criteria. The small sample size of this clinical trial limits the application of the data in other settings or studies, and does not provide robust evidence of no effect of laser in these wounds. More studies with larger sample sizes are necessary and should include different research institutes and universities, as well as additional control over self-care and prevention of disabilities procedures.
Even though the supporting evidence is weak, LLLT has been used by health care professionals in many countries around the world for the treatment of venous, pressure and diabetic chronic wounds . Our results disagree with those obtained by one previous study , where a wound cure rate of 66% was reached. However, that study was greatly limited as the authors included only four patients (12 ulcers) and had no control group. Many in vitro, in vivo and human studies report positive effects of LLLT [24–33], though there are other works that did not reach the same conclusion [34–41]. One systematic review of papers published after 1999  concluded that there is no sufficient scientific evidence to support the use of LLLT for wound healing. The author declares that new controlled studies are necessary to determine its real efficacy and to delimitate more adequate procedures for each group of patients.
Although their focus was on a different primary disease, our results are in accordance with a systematic review by Flemming and Cullum published by Cochrane Library . They found no evidence that treatment with LLLT could provide any benefit for venous leg ulcer healing. However, in one meta-analysis , the authors concluded that LLLT is an effective tool to promote wound healing. These conflicting results may be partially attributed to disparities in study design, including different laser types, variance of treatment parameters and selected samples. The evaluated papers reported no side effects related to exposure to LLLT.
Management of chronic ulcers in patients with leprosy includes different types of dressings, orthopedic and plastic surgeries, plaster casts, special footwear, splints, crutches, wheelchair use and absolute rest. Despite this, clinical experience shows that patient compliance to the therapeutic procedures is a key consideration in treatment choice and that without patient collaboration the result of the treatment can be frustrating. Low patient adherence to rehabilitation and prevention of disabilities programs (e.g. usage of appropriate footwear) indicate that more research and educational measures are necessary to improve the adoption of such strategies. More research is also needed to develop more efficient therapeutic tools.