# Quantitative Evaluation of the Clinical Evolution of Traumatic Onycholysis after Laser Treatment
## 2 Materials and Methods  
The study was approved for work with human samples by the Bioethical Commission of the University of Extremadura (ref 35/2012). Eight patients were recruited from the University Podiatry Clinic, and all of them signed a consent form. Patients had none showed clinical signs on their skin or had been diagnosed with a systemic or dermatological disease affecting the nails. The study was performed on 10 nails that after a clinical evaluation were diagnosed with onycholysis on the first toe associated with an anatomical alteration, and fungal infection was ruled out by culture. Clinical signs did not lead to suspicion of the presence of subungual exostosis as the etiology of the onycholysis, and therefore no radiological tests were performed. Nail samples were cultured on a plate with Sabouraud agar and chloramphenicol culture medium, which is selective for the isolation of dermatophyte fungi and yeasts and kept at 30 \({}^{\circ}\)C for three or four weeks. The culture was repeated three times before starting the treatment, to secure the result.  
All participants were treated with PinPointe FootLaser(tm) (Spain), an Nd:YAG 1064 nm laser with the following technical specifications: energy per pulse (max) 200 \(\upmu\)j, pulse width (max) 100 \(\upmu\)s and repetition rate (max) 30 Hz. Applying the manufacturer's protocol, participants received three sessions of treatment at monthly intervals. Each session comprised one longitudinal and one transversal pass over the nail and peripungal tissue, after debriding the injured part. During each pulse, 10 micro pulses were applied in 0.5 s, with a 0.05 s interval between micro pulses. This procedure cools the blood capillaries, reducing patient discomfort and minimizing damage to healthy tissue. The application of 10 micro pulses applies 20 J/cm2.  
To evaluate the efficacy of laser application in treating all nail pathologies and to unify the results, we applied the nail growth theory [20]. In normal conditions, the nail plate can grow from the matrix or nail bed, and its progress is from proximal to distal. Assuming that the cause of the nail disorder ceases, the nail will begin healthy regeneration, and the damaged part will move to distal. Therefore, we evaluated the percentage of the longitudinal axis in which the nail disorder appeared, because according to the nail growth theory, if the cause of the disorder were eliminated, this percentage would decrease (Figure 1). The measurement was performed before treatment and six months post treatment.  
The longitudinal axis was measured with the following guidelines. Firstly, the middle point of the nail width at the level of the onychocorneal band and hyponychium was calculated. These two points were combined to define the longitudinal axis of the nail. The total length and the affected part of the longitudinal axis were measured, and the affected percentage of the axis was obtained using the following formula: \"affected % axis = mmaffected \(\times\) 100/mm total axis\" (Figure 1). All clinical follow-up was carried out by the same researcher ([PERSON])  
The results were statistically analyzed with SPSS 15.0, applying [PERSON]'s \(t\)-test for related samples, with a statistical significance of 5% (\(p\) < 0.05).