Ingrown Toenails

Etiology

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.[2][3] Other predisposing factors for ingrown toenails include tight-fitting shoes, bad foot hygiene, hyperhidrosis, trauma, and some medications, especially epidermal growth factor receptor inhibitors (gefitinib, cetuximab).[4] 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 study results 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.[3][5] Other study results proved that bone abnormalities that increase the internal pressure in the ankle, foot, or toe might play a role in developing ingrown toenails.[1][6] However, more recent results suggest no difference in anatomical abnormalities between patients with ingrown toenails and controls.[7]

Epidemiology

There have been few investigations of the epidemiology of ingrown toenails. Previous results from studies have noted that the prevalence was 2.5% to 5%.[6] The incidence and prevalence of ingrown toenails have increased in recent years, probably due to enhanced 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 approximately 2 to 1). Ingrown toenails affect almost exclusively the hallux toenails and can occur in 1 or both nail edges. Involvement of the lateral toe edge occurs twice as much as on the medial side.[6][8]

Pathophysiology

Many theories have been proposed to explain the onset of ingrown toenails. One assumption is that it is related to excess skin surrounding the nail, which is the real culprit; this is explained by wide lateral tissue tending to bulge around the nail, leading to pressure and necrosis.[9] However, the most accepted theory is that an ingrown toenail occurs when the nail plate edge grows into the overlapping lateral nail fold, causing painful inflammation and forming granulation tissue.[8][9] Reactive ground forces due to athletic activity, obesity, and/or constricting footwear aid this penetration.[2]

History and Physical

An ingrown toenail is a straightforward diagnosis. Almost all patients present with toe pain that may cause different levels of discomfort and disability, ranging from simple difficulty with walking to a complete inability to ambulate.[8] 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 to the formation of hypertrophic granulation tissue, which increases the compression and thus adds to the swelling and discharge (stage 3).[10][11]

Evaluation

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 reveals a subungual bony proliferation. 

Treatment / Management

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 treatment modalities in case of recurrence, and other factors, including allergies to local anesthetics, pregnancy, and bleeding disorders. Conservative measures are generally recommended in mild to moderate lesions (stages 1 and 2), whereas severe lesions causing disability require surgical methods (stage 3).[8][9][10][12]

General Measures

General measures for ingrown toenails include proper footwear and correct nail trimming; this includes avoiding 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 or Epsom salt water for several minutes, followed by topical antibiotic ointment, may give relief. The application of topical steroids to hypertrophic granulation tissue may decrease inflammation.[9][13]

Conservative Techniques

• Cotton-wick insertion under the nail's corner: Cotton wisps or pledges are placed under the ingrown lateral groove corner using a nail elevator.[14]

• Dental floss technique: This is an alternative to cotton wisps. A string of dental floss is inserted under the ingrown nail to separate it from the lateral fold.[15]

• The gutter splint or sleeve technique: Gutter strips are prepared by cutting to size vinyl intravenous infusion tube from top to bottom. The lateral edge of the nail plate gets splinted with this sterilized splint plastic tube and then attached with adhesive tape or strips, giving instant pain relief.[16][17]
(B2)

• Taping procedure: One end of the tape is placed against the side of the ingrown toenail, with the rest twisted around the toe. The aim is to pull the side of the nail fold away from the nail to decrease pressure. Taping is the safest and least painful procedure among conservative options.[18]

• Nail wiring: Two holes are made at the distal edge of the nail, and an elastic wire is inserted and bent forward. The wire's elasticity may correct the deformity of the ingrown toenail. 

• Others: These include the slit tape-strap procedure, acrylic nails, and nail braces.[8][9][19]
(B2)

Surgical Techniques

Surgical procedures for ingrown toenails are performed under local anesthesia (LA). Various techniques for LA exist, including digital block, metatarsal block, or transthecal anesthesia. Any local anesthetic (lidocaine, ropivacaine, mepivacaine, or prilocaine) in 0.25% to 2% concentrations can be used. Indications for LA depend mainly on the type of surgery and the physician’s preference.

Surgical options for ingrown toenails are: 

• Spicule excision and partial matricectomy: This consists of excising the affected nail portion with a partial mechanical matricectomy.[20]
(B2)

• Chemical partial matricectomy: Chemical matricectomy is commonly performed using phenol. This procedure demonstrates a higher success rate and is less painful than mechanical matricectomy, and its success depends on good hemostasis. Other chemical agents, such as sodium hydroxide and trichloroacetic acid, can be employed.[21]
(A1)

• Wedge resection of the toenail and nail fold: This approach consists of the excision of the affected portion of the nail plate, partial matricectomy, and wedge dissection of the nail bed and the hypertrophic nail fold. Clinicians should generally avoid this technique. 

• Excision of the affected nail and total matricectomy: This is a more radical solution to ingrown toenails consisting of the affected nail and nail bed excision and a total matricectomy (chemical or mechanical). This procedure is indicated for stage IV ingrown toenails, onychogryphosis, and onychodystrophy.

• Soft-tissue nail fold excision technique: This procedure does not touch the nail; it is theorized that the nail is not the causative factor in developing ingrown toenails. This procedure consists of a wide excision of the soft tissue enveloping elliptically.[22][23]
(B2)

• Other techniques: Newer techniques, including electrocautery, radiofrequency ablation, and carbon dioxide laser ablation, have become the newest form of ingrown toenail management.[3][9][24]

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 study results have proven that simple nail avulsions lead to high recurrence rates, while phenol matricectomy has shown greater success.

Differential Diagnosis

Differential diagnosis includes mainly subungual exostosis and tumors of the nail bed (benign and malignant). If suspected, an x-ray examination that 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.[2][9]

Prognosis

Recurrences can occur following all the abovementioned procedures; 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.[11]                                                                             

Complications

Secondary infection of the nail fold, paronychia, and scarring of the nail fold are essential to consider and treat.