Ingrown toenail, also known as onychocryptosis or unguius incarnatus, is the most common nail problem encountered in both general practice and dermatology.
An ingrown toenail occurs when the nail plate grows into the periungual skin and causes inflammation and infection. It causes considerable pain, discomfort, and disability if left untreated. An ingrown toenail may present at any age, but it affects most commonly teenagers and young adults. The hallux nails are the most frequent location.
Management options range from conservative treatments to extensive surgical approaches, depending on the severity and the stage of the condition.
Improper nail trimming appears to be the most common etiology of ingrown toenails as it may lead to a nail spike that traumatizes adjacent soft tissue. Other predisposing factors for ingrown toenails include tight-fitting shoes, bad foot hygiene, hyperhidrosis, trauma, and the use of some medications, especially epidermal growth factor receptor inhibitors (gefitinib, cetuximab).
The possible involvement of intrinsic risk factors in the pathogenesis of ingrown toenails, such as abnormal nail shape and anatomical abnormalities, has been widely debated. Some studies have found that pincer-nail deformity, wide nail plates, congenital malalignment of the toenails, and thickening of the nail plate represent possible risk factors for ingrown toenails.
Other studies proved that bone abnormalities that increase the internal pressure, in the ankle, foot, or toe, might play a role in the development of ingrown toenails. However, more recent reports suggest no difference in anatomical abnormalities between patients with ingrown toenails and controls.
There have been few investigations of the epidemiology of ingrown toenails. Previous reports have noted that the prevalence was as high as 2.5 to 5% . It seems that the incidence and prevalence of ingrown toenails are increasing these last years, probably due to increased health knowledge and may also be related to lifestyle changes such as important physical activities. Incidence peaks in adolescents and young adults with a clear male predominance (male/female ratio is approximatively 2 to 1). Ingrown toenail affects almost exclusively the hallux toenails. It can occur in one or both nail edges. Involvement of the lateral toe edge occurs twice as much as the medial side.
Many theories have been proposed to explain the onset of ingrown toenails. One assumption is that it is related to the excess of skin surrounding the nail, which is the real culprit. It is explained by wide lateral tissue tending to bulge up around the nail leading to pressure and necrosis. However, the most accepted theory is that ingrown toenail occurs when the nail plate edge grows into the overlapping lateral nail fold, causing painful inflammation and leading to the formation of granulation tissue. Reactive ground forces due to obesity and/or constricting footwear aid this penetration.
An ingrown toenail is a straightforward diagnosis. Almost all the patients present with toe pain. This pain may be responsible for different levels of discomfort and disability, ranging from a simple difficulty with walking, to a complete inability to ambulate. Physical examination findings may vary depending on the stage of the disease.
The initial presentation, corresponding to stage 1, is characterized by signs of inflammation in the affected toe: pain, swelling, and erythema. The initial stage is followed by an acute infection with seropurulent drainage and ulceration of the nail fold, causing more edema and tenderness (stage 2). Chronic infection leads then to the formation of a hypertrophic granulation tissue, which increases the compression and thus adds to the swelling and discharge (stage 3).
The diagnosis of an ingrown toenail is classically based on clinical features and does not require any laboratory or radiographic tests.
If physical examination reveals a subungual nodule, an X-ray examination may be needed to rule out subungual exostosis. In such cases, it revels a subungual bony proliferation.
Treatment methods for ingrown toenails range from medical measures to surgical interventions. Indications for the treatment depend mainly on the stage of the condition, prior modalities of treatment in case of recurrence, and other factors including allergies to local anesthetics, pregnancy, and bleeding disorders. Conservative measures are generally recommended in cases of mild to moderate lesions (stages 1 and 2), whereas severe lesions causing disability require surgical methods (stage 3).
General measures for ingrown toenails include proper footwear as well as correct nail trimming; this includes avoiding of curved cutting off the lateral margins of the nail plate. General measures should also include management of the underlying factors (hyperhidrosis, onychomycosis). Soaking the affected toe in warm soapy water for several minutes, followed by the application of a topical antibiotic ointment may give relief. Application of topical steroids to the hypertrophic granulation tissue may decrease inflammation.
Surgical procedures for ingrown toenails are performed under local anesthesia (LA). There are various techniques for LA, including digital block, metatarsal block, or transthecal anesthesia… Any local anesthetic can be used (lidocaine, ropivacaine, mepivacaine, or prilocaine) in 1 to 2% concentrations. Indications for LA depends mainly on the type of surgery and the physician’s preference.
Surgical options for ingrown toenails are:
Thus, surgical treatment options for ingrown toenails are numerous, and there is no consensus on the technique of choice. The ideal procedure should lead to the best functional and aesthetic outcome, as well as a low rate of recurrence. Many studies have proven that simple nail avulsions lead to high recurrence rates, while phenol matricectomy has shown greater success.
Differential diagnosis includes mainly subungual exostosis and tumors of the nail bed (benign and malignant). If suspected, an X-ray examination which reveals the subungual bony proliferation can confirm the diagnosis of subungual exostosis. Malignant tumors to consider are subungual melanoma and subungual squamous cell carcinoma, which can be locally aggressive.
Recurrences can occur following all the procedures mentioned above. They result from incomplete matricectomy and regrowth of a spicule from the lateral horn. Simple nail avulsion has the highest recurrence rate (70%). Chemical matricectomy and laser matricectomy showed lower recurrence rates than mechanical matricectomy.
Secondary infection of the nail fold, paronychia, and scarring of the nail fold are essential to consider and treat.
Ingrown toenails are usually encountered and managed by a wide variety of healthcare professionals, including general practitioners, dermatologists, general and orthopedic surgeons, and podiatrists. Specialty nursing involvement will generally be with changing dressings and monitoring healing progress, ensuring the patient is using any accompanying medications appropriately (e.g., topcial antibiotics). The specialty-trained foot and nail nurse should report all progress or setbacks to any clinicians involved. The foot and nail nurse should also assist the clinician with patient and family education in training the patient and family in regards to appropriate nail trimming techniques. An interprofessional team approach approach is thus, essential to render the best patient care and achieve optimal outcomes. [Level 5]
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