Onychocryptosis, commonly known as an ingrown toenail, is one of the most frequent complaints seen in podiatric and general practice. It occurs when the edge of the nail plate penetrates the surrounding soft tissue, triggering inflammation, pain, infection, and often the formation of hypergranulation tissue. While mild cases respond to conservative measures such as proper nail trimming, warm soaks, and cotton wisp insertion, recurrent or severe cases typically require surgical intervention. Among the surgical options available, chemical matricectomy using phenol has become the most widely practiced technique worldwide due to its high success rate, relative simplicity, and low complication profile.
Understanding the Problem
The nail plate grows from the germinal matrix, a specialized area of tissue beneath the proximal nail fold. When a portion of the nail border digs into the lateral nail fold—often due to improper cutting, tight footwear, trauma, or an inherently curved nail plate—the body responds with an inflammatory reaction. If left untreated, this can progress to chronic infection, abscess formation, and the growth of exuberant granulation tissue that further traps the nail edge, creating a self-perpetuating cycle. Surgical treatment aims to permanently eliminate the offending portion of the nail so it can no longer intrude into the soft tissue.
The Rationale for Chemical Matricectomy
Historically, ingrown toenails were treated with wedge resection procedures, such as the Winograd or Zadik operations, which involve surgically excising a portion of the nail plate along with the corresponding germinal matrix tissue using a scalpel. While effective, these procedures require more extensive dissection, meticulous hemostasis, and often produce more postoperative pain and longer healing times. Phenolization emerged as an alternative that achieves matrix destruction chemically rather than mechanically, avoiding the need to cut and remove matrix tissue directly.
Phenol (carbolic acid) is a caustic, protein-denaturing agent that, when applied directly to matrix tissue, causes controlled chemical cauterization. This destroys the germinal cells responsible for producing the offending portion of the nail, preventing that segment from regrowing. Because the destruction is chemical rather than purely mechanical, the technique can be performed with a smaller incision, less bleeding, and reduced technical difficulty compared to traditional excisional matricectomy.
The Surgical Procedure
The procedure is typically performed under local anesthesia using a digital block, most commonly with plain lidocaine (epinephrine is generally avoided in digital blocks, though modern evidence increasingly supports its cautious use). Once adequate anesthesia is achieved, a pneumatic or rubber tourniquet is often applied at the base of the toe to create a bloodless field, which is essential because phenol’s efficacy can be diminished in the presence of blood.
The offending lateral or medial border of the nail plate—or in severe bilateral cases, the entire nail—is then avulsed, meaning it is separated and removed from the nail bed and matrix using a nail elevator and English anvil nail splitters. This exposes the germinal matrix at the base of the nail fold.
A cotton-tipped applicator or small pledget soaked in 88% phenol solution is then applied directly to the exposed matrix tissue, typically for one to three applications lasting approximately thirty seconds to one minute each, with cleaning between applications using isopropyl alcohol or saline to remove the coagulated, whitened tissue produced by the phenol. The alcohol also helps neutralize residual phenol, reducing the risk of excessive tissue damage to surrounding structures. The tourniquet is then released, hemostasis is confirmed, and the toe is dressed with an antiseptic, non-adherent dressing.
Postoperative Care and Recovery
Patients are generally advised to keep the foot elevated and dry for the first twenty-four to forty-eight hours, after which daily dressing changes with antiseptic soaks are recommended until the wound has fully granulated and epithelialized, a process that typically takes three to six weeks. Unlike excisional techniques that involve sutured wounds, phenol matricectomy leaves an open wound that heals by secondary intention. Patients often experience a moderate, malodorous discharge during the healing phase, which is a normal consequence of the chemical cauterization and tissue sloughing rather than necessarily a sign of infection, though this can occasionally be alarming if patients are not properly counseled beforehand.
Efficacy and Complications
Numerous clinical studies and systematic reviews have demonstrated that phenol matricectomy achieves recurrence rates generally in the range of 1 to 8 percent, which compares favorably to, or exceeds, the outcomes of traditional excisional surgery. The technique is particularly valued for its reproducibility even among less experienced surgeons, since the depth and extent of matrix destruction is somewhat self-limiting due to the chemical properties of phenol, unlike a scalpel, which requires precise anatomical knowledge to avoid leaving residual matrix tissue.
Complications, while relatively uncommon, can include prolonged drainage, delayed wound healing, postoperative infection, and rarely, thermal or chemical injury to adjacent tissue if phenol is not carefully controlled. This is called a phenol burn. Some patients also report temporary hypopigmentation of the treated nail fold skin, particularly in individuals with darker skin tones, due to phenol’s cytotoxic effect on melanocytes. Diabetic patients and those with peripheral vascular disease require careful case selection, as impaired healing capacity may increase the risk of complications in this population.
Advantages Over Alternative Techniques
Beyond its strong success rates, phenolization offers several practical advantages. It requires minimal surgical instrumentation, avoids the need for suturing, and generally results in less intraoperative bleeding than excisional approaches. The procedure can typically be completed in fifteen to twenty minutes in an outpatient or office setting, making it highly accessible and cost-effective. Patient satisfaction tends to be high, given the relatively quick return to normal activity and footwear compared to more invasive surgical alternatives.
Phenol matricectomy has become the gold standard for definitive surgical management of recurrent or severe ingrown toenails. By chemically ablating the germinal matrix responsible for producing the offending nail border, the technique offers a minimally invasive, technically reproducible, and highly effective solution with low recurrence rates. While it requires patient tolerance of a longer secondary-intention healing process and careful postoperative wound care, its overall safety profile and consistent outcomes have cemented its place as a preferred approach in modern podiatric and dermatologic surgical practice.