Ingrown Toenail

Vol. 13 •Issue 8 • Page 45
Ingrown Toenail

End the Cryptosis Cycle

Ingrown toenail (cryptosis) is a common condition that many nurse practitioners see routinely. A growing consensus suggests that partial nail resection (PNR) in conjunction with chemical matricectomy is the most effective treatment for cryptosis.1

Selective matrix ablation, or partial matricectomy, artificially narrows the toenail permanently. In most cases, this restructuring provides a definitive solution to the cryptotic toenail.2 Performing a PNR without the matricectomy will not solve the problem. The nail will simply replicate its previous cryptotic condition, and the cycle of pain will begin again.

The goal of treatment is to relieve pain by resolving inflammation and infection and to prevent cryptosis from reoccurring. To achieve this, skillful reduction of the width of the ingrowing toenail is needed. An implied secondary goal is to perform this procedure in a way that will produce a cosmetically pleasing outcome.

This article summarizes my experience treating ingrown toenail in at least 300 patients. The photographs accompanying this article document some of these cases and were taken with each patient’s permission.


The anatomy of the toenail is illustrated in Figure 1.

The nail advances predictably in a longitudinal direction owing to macroscopic ridges that correspond to grooves in the nail bed. The nail adheres to the matrix via the onychodermal band. This bond is best left undisturbed, so avoid removing the entire nail except under extenuating circumstances. If the entire nail is removed, it may not grow back in proper alignment. This conclusion is anecdotal, based on reports from patients and other providers.

The nychials create a protective seal around the matrix. The eponychium forms the proximal skin fold and overlies the nail root. To the lateral and medial margins are the paronychiums. A paronychia is simply an infected paronychium and does not necessarily indicate an ingrown toenail.3

Distally, the hyponychium forms a tight seal beneath the free edge; it also forms the fleshy tip of the dorsal toe. The hyponychium, like the other nychials, serves as a protective seal. If these structures are damaged by overtrimming or overt trauma, the nail bed becomes exposed and at risk for bacterial or fungal infection. Bacterial infection causes paronychia, while onychomycosis is a subungual fungal infection.

Figure 2 shows the foot of a man who self-managed his ingrown toenail by aggressively trimming. The diagnosis in this case was stage 3 onychocryptosis. A bilateral partial nail resection with selective matricectomy of the paronychial nail matrix resolved this problem.


Begin the assessment with a complete health history. Of special concern are disorders that impair the vascular system, such as diabetes.4 If invasive intervention becomes necessary, the existence of vascular problems is an influential factor in treatment. Ask about previous treatment attempts. Patients with cryptosis often have a long history of numerous attempts at treatment with escalating aggressiveness.

Blunt trauma can provoke cryptosis, but poorly fitting shoes are far more likely to be the culprit. Always look at both feet, not just the one the patient complains about. By assessing both feet, you will gather added and sometimes unexpected information. Look at all the toes and assess the general condition of the entire foot. Unusual contour or tone can be a sign of myelodysplasia, hypothyroidism or cerebral palsy.5 Figure 3 shows Beau’s lines, which may indicate severe systemic disease. Notice the lack of symmetry as well as the trauma to the right foot.

Evaluate the severity of ingrowth by the extent of erythema, edema, exudates, hypertrophy and granulation tissue. These are indicators only; patients often complain of toe pain when none of these are present. Close inspection allows you to determine whether the condition is ingrown toenail. Figure 4 shows bilateral stage 3 onychogryposis. (This article presents a new system of diagnosis and staging that I developed.) Although this patient obviously has a pincer nail, the toe itself is free of significant severity indicators.

In addition to my own staging, I classify ingrown toenails as primary or secondary. Primary ingrown toenails have a congenital predisposition to cryptosis, while secondary ingrown toenails are provoked by factors and events such as inappropriate nail trimming, poorly fitting shoes, trauma or arthritis. Careful evaluation reveals a continuum rather than two distinct groups, and this distinction provides a basis to initiate patient education. Understanding the contributing factors will enhance the ability to promote effective lifestyle changes.

Onychogryposis refers to cryptosis provoked by a hypercurved (pincer) nail; onychomycosis is an ingrown toenail resulting from a subungual fungal infection.3 Often used as a generic term to describe all ingrown toenails, onychocryptosis specifically denotes ingrown toenails other than pincer or mycotic cryptosis. A fourth type that may require treating with a PNR is chronic or recurring paronychia. This condition is rare; even acute paronychias of the toe are unusual.

The objective findings (severity indicators) traditionally distinguish the stage of ingrowth.3,5-7 However, severity indicators may or may not be present (Figure 2). Therefore, using objective findings to stage ingrown toenail is unpredictable. The traditional stages of cryptosis are listed in Table 1.1

Patients often present without granulation tissue or lateral nail fold hypertrophy, yet they experience significant pain from advanced cryptosis. Exceptions are so numerous as to become the rule.

Figure 5 graphically depicts this staging dilemma. This 6-month-old boy had granulation tissue on all three paronychiums, yet his condition was adequately managed using conservative treatment.

So why bother staging ingrown toenails? What real value does it serve unless it advances the treatment strategy?

I suggest a new staging system based not on severity indicators but on the only consistent criterion: the treatment plan. The stages of cryptosis should progress from 1 through 4 based on the degree of treatment invasiveness required to resolve the condition. This proposed system is outlined in Table 2.

My system reflects a treatment strategy based on the degree of invasiveness required to solve the problem. So how do you select a treatment? You and the patient reach the decision together after careful assessment and discussion. No precise answer or set of specific points can or should direct the course of treatment. Informed consent combined with the discerning eye of the skillful provider will determine the correct stage of cryptosis — the treatment plan — for any given patient.

Stage 1 Ingrown Toenail

Stage 1 ingrown toenail requires noninvasive care. Patient education alone may be all that is required. The typical patient with stage 1 cryptosis believes that aggressive nail trimming will prevent ingrown toenails. Such a patient may only require a point-by-point education session on self-care techniques. Sounds simple, but it is not. Prepare to overcome lifelong, entrenched beliefs that lead to presentations such as that shown in Figure 6.

Stage 2 Ingrown Toenail

Stage 2 ingrown toenail displays minimal cryptosis and requires limited invasive intervention. Stage 2 cryptosis will not resolve without invasive intervention. However, the degree of cryptosis does not warrant removing any part of the toenail.

The logical option is to perform a nail lift. After performing a digital block (if required), gently lift the ingrown edges out of the crypt. Then, place gauze or cotton under the leading edge of the toenail. This technique suspends the nail, preventing it from falling back into the paronychial trench. This sounds good in theory, but in actual practice few patients present with toenails that are well suited for this procedure. Moreover, the patients who are candidates for stage 2 treatment often cannot tolerate the ongoing discomfort caused by replacing the cotton.

Another problem with this approach is that it exposes the nail bed to potential fungal infection. Additionally, the outcomes for stage 2 repair vary along unpredictable lines. Hence, I consider stage 2 treatment a low-yield procedure and recommend it only for the motivated patient. Carefully screen your patients before selecting this protocol.

Stage 3 Ingrown Toenail

Stage 3 ingrown toenail is characterized by significant ingrowth that requires moderately invasive intervention (Figure 7). The most common ingrown toenail is stage 3 onychocryptosis, but all types of cryptotic toenails progress so slowly that the patient usually defers seeking care. Increasing pain, coupled with ever more frequent trimming, eventually forces the patient to ask for help.

If you and the patient agree that a moderately invasive procedure is desirable, a partial nail resection is the preferred option. The diagnosis for ingrown toenail should specify the severity by stage, then by type (onychocryptosis, onychogryposis or onychomycosis).

Invasive intervention implies some degree of altering the physical. In the case of stage 3, the severity of cryptosis is such that it will not resolve without physical alteration of the toe. Provided that a less invasive procedure will not solve the problem, I recommend the PNR and matricectomy as first-line treatment for ingrown toenail. Alternative options (partial wedge resection, surgical matricectomy or Zadik procedure) are best left to providers specializing in minor surgery.

The odds in favor of successful outcome with PNR are high, with some of the literature citing rates of 90% or higher. My clinical experience suggests even better success rates. The only drawback to PNR is that it alters the natural appearance of the toe. When the results are compared with the preprocedure cryptotic toenail, however, even this alteration is an improvement in most cases. Nevertheless, the patient needs to know about the irreversibility of this procedure. Informed consent — verbal and written, signed and witnessed — is fundamental to this and all invasive procedures.

The outcome of PNR can be so good that distinguishing a toe that has undergone the procedure years earlier is sometimes difficult. Regardless, the patient ought to know that the outcome of invasive procedures is unpredictable. If the patient finds this distressing, suggest the less aggressive nail lift. Informed consent also should include education about the higher risk of treatment failure associated with less aggressive measures, such as stage 2 repair. Failure rates can be as high as 70%.

How do you determine when to postpone and when to proceed? Mild to moderate inflammation may slow the anesthetic effect of lidocaine but is not in itself a reason to postpone the treatment of ingrown toenail. Overt infection, however, presents a more complicated problem. If the toe is infected, proceed with the PNR but postpone the partial matricectomy. Allow the toe to heal before performing the procedure, because matricectomy on an infected toe may cause the nail bed to dehisce all the way to the bone. Pay serious attention to this warning. Knowing that this problem will heal with antibiotics will not calm the patient whose distal phalanx is plainly visible. Although rare, osteomyelitis is a possibility in these circumstances. When in doubt, obtain x-rays.

Since erythema is frequently a presenting factor with stage 3 cryptosis, a 1-week waiting period is useful to reduce inflammation before PNR. Cephalexin (Keflex) 500 mg three times daily is a good choice for its antimicrobial and anti-inflammatory properties. If the toe is grossly inflamed, a digital block will not achieve total anesthesia. Preoperative pain control is always an option but seldom is necessary.

Step 1: Position the Patient

Have the patient assume the recumbent position, with knees flexed sufficiently to allow his or her feet to set flat on the procedure table and with the tips of the toes approximating the edge.

Step 2: Anesthesia

Inject 1 mL to 2 mL of lidocaine 2% at a point directly between the first and second toes. This anesthetizes the medial plantar nerve. The rationale is that few pain receptors exist between the toes; the lateral great toe is already partially numb a few minutes later. This allows for a nearly pain-free digital block (Figure 8).

Perform a standard digital-ring block by injecting approximately 1 mL on each side, top and bottom. Some authors warn that a full-ring block may cause a tourniquet effect and advise restricting the total volume of lidocaine to 2 mL.8 However, my clinical experience favors the full-ring block to achieve pain control, and I typically inject 5 mL or even more. Other published reports state that anesthesia is achieved with 3 mL to 6 mL of 1% plain lidocaine in a digital-ring block fashion.3

Avoid injecting additional lidocaine directly beneath an inflamed cryptotic nail bed. This may expedite total numbness but may also cause permanent partial numbness to that area. Based on historical, anecdotal evidence only, injecting too much local lidocaine may provoke permanent partial numbness.

On the other hand, clinical experience supports published findings that the effects of vasoconstrictors (lidocaine with epinephrine) in digital analgesia may not be problematic.8,9 Prudent use is nevertheless encouraged.

Start the digital block at the proximal lateral great toe. Partial numbness of the lateral great toe occurs rapidly due to the plantar nerve block. Inject the top proximal toe, followed by the medial proximal, and conclude with the bottom proximal toe.

As long as the toe is free of significant inflammation, complete numbness occurs rather quickly. One option is to perform the digital block using less lidocaine and then return to the procedure 10 to 15 minutes later.8 This alternative allows for less local anesthesia, an important consideration for diabetes patients with peripheral vascular disease.

After the digital block is complete, immerse or scrub the foot in diluted povidone iodine (Betadine) solution. Performing this preparation after the digital block provides time for the lidocaine to take effect.8

Step 3: Partial Nail Resection

Using iris scissors (or larger surgical scissors for heftier nails), incise the nail longitudinally from a point starting at the hyponychium. Start the dissection at approximately 20% of the affected portion of nail. Figure 9 shows a case in which the incision removed too much nail for optimal cosmetic outcome. Removing too much nail increases disfigurement, but not removing enough invites treatment failure. Experience and a critical eye will help determine the correct amount.

Avoid using an elevator (such as a hemostat used as a probe) to separate the onychodermal bond; doing so unnecessarily dislodges more of the body toenail from its bed than using scissors alone to dissect the nail. Limiting the trauma of the procedure shortens healing time.

Step 4: Relieve Cryptosis

Gently insert mosquito hemostat forceps under the dissected portion of the soon-to-be-discarded cryptotic toenail. Fully insert the hemostat and secure the nail root before clamping down. Try to remove the nail sliver from the sulcus in one piece.

Always probe the sulcus for debris. Leaving any portion of nail root or extraneous tissue will invite treatment failure. Even loose cuticle previously attached to the nail root will prevent healing.

Step 5: Hemostasis

Successful nail matrix ablation requires hemostasis. The issue of employing vasoconstrictors (lidocaine with epinephrine) again comes into play. For a younger, otherwise healthy patient, use lidocaine 1% with epinephrine.8,9 For older patients and patients with diabetes, choose lidocaine 1% or 2% without epinephrine. Decrease the total volume of lidocaine for these patients.8

To exsanguinate the digits, apply a tourniquet. I recommend the Penrose for this procedure. Hemostasis is only required for the few minutes it takes to perform the actual matricectomy, not the entire procedure. Do not apply the tourniquet until needed.

Step 6: Matricectomy

The purpose of a PNR is to permanently solve ingrown toenail. To accomplish this requires preventing the nail from growing back into the paronychial sulcus. Thus, the last step is nail matrix ablation.

Several mediums and devices are available for matricectomy. Phenol is the most often mentioned in literature, followed by sodium hydroxide. Electrocauterization will ensure matrix ablation but may cause collateral damage, such as that seen in Figure 10. For this and other reasons, phenol is preferred.

Although phenol is a weak acid and it does not cause a full-thickness dermal burn, it can cause severe second-degree burns if not neutralized or diluted. For nail ablation, the recommended dilution of phenol is 80% to 89%.2

Apply phenol by first protecting the surrounding tissue. Spread a thin layer of Vaseline on the nychials to prevent accidental chemical burns. Thoroughly dry the sulcus with a surgical sponge. Dip a miniature cotton swab in a fresh bottle of phenol and insert it into the now exposed sulcus of the affected toe.

The time of exposure to phenol is important. Insufficient exposure allows the matrix to escape complete ablation; too much will cause a halo-shaped burn on the surrounding tissue. On average, allow only 1 minute of exposure to phenol before thoroughly rinsing the sulcus with isopropyl alcohol. Although phenol is an alcohol, isopropyl dilutes its caustic action. After flushing the sulcus with isopropyl, irrigate the entire toe with normal saline.

A thorough review of the literature produces about as many matricectomy protocols as articles surveyed. Some authors prescribe a 1-minute phenol exposure while others recommend three separate 30-second applications. To complicate this issue just a bit, not all tissue ablates at the same rate.2,4

More exposure time is required for the younger patient. An older patient, or one with poor circulation, may not require more than a 30-second exposure to phenol. Plan exposure time before starting.

Figure 11 shows a patient 3 weeks after bilateral PNR with phenol matricectomy. The toe is completely healed, a significant improvement over electrocauterization. (Figure 4 shows the same patient months before his pincer nail became acutely inflamed.)

Sodium hydroxide is gaining wide acceptance among podiatrists for chemical matricectomies. Sodium hydroxide may not cause as much drainage as phenol, and reportedly the healing time is even faster.10 Be aware that if sodium hydroxide is not completely neutralized with acetic acid (vinegar), it will continue to dissolve tissue.

Exposure time with sodium hydroxide is about the same as for phenol. Respect both chemicals for their benefits as well as their potential for untoward adverse outcomes. Proceed with caution by advancing only after educating yourself.

Not all providers encounter a high number of patients with ingrown toenail. Stocking phenol or sodium hydroxide may not be appropriate for such clinic settings. However, most outpatient clinics have a hyfrecator for electrocautery. This device can adequately perform a matricectomy.

The chief drawback to electrocautery matricectomy is the learning curve required to determine how much burn is required. With insufficient cauterization, the patient will likely experience another ingrown toenail; too much and the patient will experience a lingering, unnecessary burn. Figure 10 graphically demonstrates the latter. It shows presentation 14 days after matricectomy by electrocautery. This excessive burn was caused by exposing the sulcus using a hemostat rather than a nonmetallic object. Avoid collateral damage during electrocautery by exposing the matrix using a nonmetallic instrument rather than metal forceps. Adjacent metal objects will augment the cauterizing effect.

Other Options

Other tools and methods for achieving matrix ablation are available, including trichloroacetic acid, nitrous oxide, negative galvanism and silver nitrate sticks. The wedge PNR (a surgical excision of the germinal matrix known as the Zadik operation) is another option, but this procedure is best left to experienced specialists.8

Stage 4 Ingrown Toenail

In the event that a toenail becomes grossly cryptotic, and after careful consideration, patient and provider may decide to totally and permanently remove the affected toenail. Because of the resulting disfigurement, this option is not recommended for anyone new to treating cryptosis.

Most patients who have reached this stage of ingrown toenail are pleased with the result because it ends their torment. Figure 12 shows a toe 6 months after undergoing a complete matricectomy. On initial presentation, the inflamed toe and severely impacted toenail left no reasonable option other than aggressive intervention. Owing to the fleshy hyponychium capturing the advancing, hypertrimmed toenail, a simple bilateral nail resection would not solve this man’s problem. After two rounds of antibiotics and several postponements, I suggested a complete matricectomy (CM). He immediately agreed.

CM is a total matrix ablation. The procedure itself differs little from the PNR except for one all-important point: informed consent. Both procedures are irreversible, but stage 4 matricectomy prevents the entire nail from ever growing back. Stress this point and give the patient ample time to consider all issues.

The initial protocols for CM are the same as for PNR. The differences begin with relieving cryptosis (step 4). Instead of performing a partial resection, the entire nail is removed. Phenol is then applied to the proximal half of the nail bed for 1 to 2 minutes, then thoroughly rinsed with isopropyl alcohol and finally flushed with normal saline.

Since the primary function of the human nail is to protect the underlying digit, deciding whether to perform a CM is the real issue.8 The provider must first weigh other options. Will a less aggressive procedure accomplish the desired results?

Case Example

The patient in Figure 13 is a 44-year-old Hispanic man with diabetes who has experienced ingrown toenails since his early teens. Over the years, he has endured four PNRs — the first three by providers who did not perform matricectomy. Thirty years later, the same toe is again painful, only now the pain extends to the lateral paronychium.

Objective findings included mild edema of the lateral and distal nychials, no exudates, no hypertrophy, no granulating tissue, and no discharge. Pedal pulses were plus 2, he had intact sensation to touch, and his skin was warm and dry. Incidental assessment findings included pincer nail of the first digit of the right foot and the third digit of the left foot. The latter showed mild inflammation of the lateral and distal nychials.

The physical exam revealed only mild cryptosis and a lack of significant severity markers. Additionally, this patient had well-controlled type 2 diabetes. The patient’s lengthy history of treatment failures favored CM. Any attempt to perform another PNR would leave this already tortured toenail too narrow to be viable.

Three factors outweighed the increased risk of the procedure due to diabetes. With special consideration performing the digital block, this patient’s circulation was adequate to cope with a modified period of exsanguination. Secondly, the patient had already endured four attempts to solve the problem. Later in his life, his vascular condition might have precluded invasive treatment.

Because of his lengthy history of treatment failures and his request for a complete and permanent removal of the offending toenail, I performed a stage 4 complete matricectomy. Subsequent follow-ups over the past year have proved this decision correct, and the patient is pleased.

Aftercare and Follow-Up

Immediately following an invasive repair of an ingrown toenail, swaddle the toe with cling wrap dressing. Prescribe antibiotics (usually cephalexin 500 mg by mouth three times a day for 7 days before and after a PNR or CM) plus nonsteroidal anti-inflammatories for pain. Stronger pain medications are not usually required; patients typically report having less pain following a PNR or CM than they had before surgery.

Instruct patients to remove the dressing after 24 hours and to avoid applying bandage strips. Instead, allow the toe to dry out by exposing it to air. Patients should anticipate some serosanguineous drainage. When phenol is used for matricectomy, the sulcus is usually dry and healing is under way within 2 weeks. This is not the case with electrocautery. To manage drainage, apply a 4-inch-by-4-inch bandage over the toe as an absorbent, allowing the wound to breathe.

When to Refer

Specialist referral depends on your own clinical judgment balanced by the severity of the presenting patient. Knowing your limits is fundamental to the healing arts. How will you accept the consequences of intervention, and how likely is it that the patient will?

To press this point, return to Figure 5. This young boy had double bilateral onychogryposis. His father and grandfather had a history of ingrown toenails. Is his condition primary, an inherited condition? One would think so; however, his mother had dressed him in a pair of trendy tennis shoes. I recommended a switch from baby tennis shoes back to baby booties. This simple intervention produced rapid, positive results.

Recently, this child was back in my clinic for a routine childhood illness. The inflammation and granulating tissue had resolved on all but the left lateral great toe. Since I had previously referred this patient to a specialist, what stage of cryptosis was appropriate for the diagnosis?

A quick addition to my staging system solved this quandary: stage 5 for ingrown toenail referrals. Creating your own staging system has its advantages!


1. Zuber TJ. Ingrown toenail removal. American Family Physician. 2002;65(12):2547-2552.

2. Boberg J. Scientific analysis of phenol nail surgery. Journal of the American Podiatric Medical Association. 2002;92(10):575-579.

3. Weaver TD, et al. Ingrowing toenails: management practices and research outcomes. International Journal of Lower Extremity Wounds. 2004;3:22-34.

4. Giacalone VF. Phenol matricectomy in patients with diabetes. Journal of Foot and Ankle Surgery. 1997;36(4):264-267.

5. Manusov EG., et al. Evaluation of pediatric foot problems, part 1. The forefoot and the midfoot. American Family Physician. 1996;54(2):592-606.

6. Ogur R, et al. Managing infected ingrown toenails: longitudinal band method. Canadian Family Physician. 2005;February:207.

7. Zuber TJ, Pfenninger JL. Management of ingrown toenails. American Family Physician. 1995;52:181-190.

8. Tollafield DR, Merriman LM. Clinical Skills in Treating the Foot. London, England: Churchill Livingstone; 1997.

9. Katis P. Epinephrine in digital blocks: refuting dogma. Canadian Journal of Emergency Medicine. 2003;5(4):245-246.

10. Ozdemir E, et al. Chemical matricectomy with 10% sodium hydroxide for treatment of ingrowing toenails. Derm Surg. 2004;30(1):26-31.

Keith Seidel is a master’s-prepared family nurse practitioner who practices at a correctional facility in Ft. Stockton, Texas. He is also a member of the adjunct nursing faculty at Texas Tech University in Lubbock.

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