Subungual exostosis (SE) is a benign bony growth that forms beneath the toenail, typically affecting the distal phalanx of the toes. This condition is relatively rare but can cause significant discomfort, deformity, and even functional limitations if left untreated. In this article, we will explore the causes, diagnosis, treatment, and potential complications of subungual exostosis, providing a comprehensive understanding of this condition in simple, accessible language for a general audience.
How Common It Is and Who Gets It? (Epidemiology)
Subungual exostosis is a rare condition, often affecting the big toe. It is typically seen in individuals who have experienced trauma to the toe or those with a family history of bone growths under the toenail. The condition is more common in adults, though it can occur in younger individuals as well.
Why It Happens – Causes (Etiology and Pathophysiology)
The exact cause of subungual exostosis remains unclear, but trauma, infection, or chronic irritation are believed to contribute to its development. In some cases, a hereditary component is suspected, though not all cases are linked to family history. The lesion forms as a result of abnormal bone growth beneath the toenail.
How the Body Part Normally Works? (Relevant Anatomy)
The subtalar joint, located between the talus and calcaneus bones, is essential for walking on uneven surfaces. Subungual exostosis occurs beneath the toenail, most commonly affecting the big toe. The bony growth arises from the tip of the distal phalanx, which is the bone at the end of the toe.
What You Might Feel – Symptoms (Clinical Presentation)
The most common symptoms of subungual exostosis include:
- Pain: Pressure from the growth beneath the nail can cause discomfort, especially when walking or putting weight on the toe.
- Swelling: A noticeable lump under the nail, which may deform the nail and push it upward.
- Nail Deformities: As the growth enlarges, it can lead to nail detachment and changes in the nail’s shape.
- Discoloration: The nail may become discolored, often appearing white or yellowish due to pressure from the exostosis.
How Doctors Find the Problem? (Diagnosis and Imaging)
Diagnosing subungual exostosis can be challenging, as its symptoms may resemble other toe and nail conditions, such as fungal infections or warts. A thorough medical history, including any previous trauma to the toe, is essential. Radiographs (X-rays) are the primary diagnostic tool, providing clear images of the bony growth. In some cases, MRIs may be used for a more detailed view of soft tissues and bone structure.
Classification
Subungual exostosis is typically classified as a benign bony lesion, often localized to the big toe. The severity of symptoms can range from mild discomfort to significant deformity and pain. The lesion is classified by its size and the degree of impact it has on the nail and surrounding tissues.
Other Problems That Can Feel Similar (Differential Diagnosis)
Conditions that may present with similar symptoms include warts, fungal infections, or other benign tumors such as osteochondromas. Accurate diagnosis is essential to differentiate subungual exostosis from these conditions, ensuring proper treatment.
Treatment Options
Non-Surgical Care:
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- Non-surgical treatments like pain management with NSAIDs or cushioning devices may provide temporary relief, but they do not address the underlying bony growth.
Surgical Care:
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- The primary treatment for subungual exostosis is surgical excision. The goal is to remove the bony growth while preserving the nail bed and minimizing damage to surrounding tissues. Several techniques are available, with the most successful being marginal excision, which involves removing the growth down to normal bone tissue.
Recovery and What to Expect After Treatment
After surgery, patients typically need to wear a protective cast or shoe for several weeks. The recovery process involves limited weight-bearing for 6–8 weeks, followed by gradual reintroduction to normal activities. Physical therapy may be recommended to improve mobility and prevent complications like abnormal nail growth. Regular follow-up visits are essential to ensure proper healing.
Possible Risks or Side Effects (Complications)
- Onychodystrophy: Abnormal nail growth can occur if the nail bed is not properly preserved.
- Recurrence: The growth may regrow if the excision was not thorough.
- Infection: While rare, infections can occur and are treatable with antibiotics.
- Delayed Diagnosis: Misdiagnosis can lead to worsening symptoms and more complicated treatment.
Long-Term Outlook (Prognosis)
The prognosis for patients undergoing subungual exostectomy is generally excellent. Most patients experience significant pain relief and a return to normal activities after surgery. The recurrence rate is low, especially when the excision is performed thoroughly.
Out-of-Pocket Costs
Medicare
CPT Code 28108 – Subungual Exostectomy (Excision of Bone Spur Beneath the Toenail): $99.08
Medicare Part B typically covers 80% of the approved cost for this procedure once your annual deductible has been met, leaving you responsible for the remaining 20%. Supplemental Insurance plans such as Medigap, AARP, or Blue Cross Blue Shield generally cover that remaining 20%, reducing or eliminating out-of-pocket expenses for Medicare-approved surgeries. These plans work alongside Medicare to fill the coverage gap and lower the patient’s financial responsibility.
If you have Secondary Insurance, such as TRICARE, an Employer-Based Plan, or Veterans Health Administration coverage, it acts as a secondary payer. These plans generally cover any remaining coinsurance or small deductibles, which typically range from $100 to $300, depending on your plan and provider network.
Workers’ Compensation
If your subungual exostectomy is required due to a work-related injury, Workers’ Compensation will cover all related medical expenses, including surgery, rehabilitation, and follow-up care. You will not have any out-of-pocket expenses, as the employer’s insurance carrier pays directly for all approved treatments.
No-Fault Insurance
If your subungual exostectomy is due to an automobile accident, No-Fault Insurance will typically cover the full cost of the procedure and recovery. The only potential out-of-pocket cost may be a small deductible or co-payment depending on your insurance policy.
Example
James Turner needed a subungual exostectomy (CPT 28108) to remove a painful bone spur beneath his toenail. His estimated Medicare out-of-pocket cost was $99.08. Since James had supplemental insurance through AARP Medigap, his remaining balance was fully covered, leaving him with no out-of-pocket expenses for the surgery.
Frequently Asked Questions (FAQ)
Q. What is Subungual Exostosis?
A. Subungual exostosis is a benign bony growth that forms under the toenail, often causing pain, swelling, deformity, and in some cases, nail detachment.
Q. What causes Subungual Exostosis?
A. The exact cause is unclear, but trauma, chronic irritation, or infection are common factors. There may also be a hereditary component in some cases.
Q. How is Subungual Exostosis diagnosed?
A. Diagnosis involves a physical examination and imaging tests, such as X-rays, to confirm the presence of the bony growth and differentiate it from other conditions like warts or infections.
Q. What is the treatment for Subungual Exostosis?
A. The primary treatment is surgical excision of the bony growth, with care taken to preserve the nail bed and minimize complications like deformities or recurrence.
Q. What is the recovery process after Subungual Exostectomy?
A. After surgery, patients may need to wear a protective dressing or shoe for several weeks. Follow-up care is essential to monitor healing and prevent complications like abnormal nail growth.
Q. What are the potential complications of Subungual Exostectomy?
A. Complications may include infection, abnormal nail growth (onychodystrophy), and recurrence of the exostosis if the excision was incomplete.
Q. Can Subungual Exostosis be prevented?
A. Preventing Subungual Exostosis involves avoiding trauma or excessive irritation to the toenail, as well as proper foot care and wearing appropriate footwear.
Q. What is the prognosis after Subungual Exostectomy?
A. The prognosis is generally excellent, with most patients experiencing pain relief and improved foot function, and a low risk of recurrence if the excision is performed properly.
Q. What is Subungual Exostosis?
A. Subungual exostosis is a benign bony growth that forms under the toenail, often causing pain, swelling, deformity, and in some cases, nail detachment.
Q. What causes Subungual Exostosis?
A. The exact cause is unclear, but trauma, chronic irritation, or infection are common factors. There may also be a hereditary component in some cases.
Q. How is Subungual Exostosis diagnosed?
A. Diagnosis involves a physical examination and imaging tests, such as X-rays, to confirm the presence of the bony growth and differentiate it from other conditions like warts or infections.
Q. What is the treatment for Subungual Exostosis?
A. The primary treatment is surgical excision of the bony growth, with care taken to preserve the nail bed and minimize complications like deformities or recurrence.
Q. What is the recovery process after Subungual Exostectomy?
A. After surgery, patients may need to wear a protective dressing or shoe for several weeks. Follow-up care is essential to monitor healing and prevent complications like abnormal nail growth.
Q. What are the potential complications of Subungual Exostectomy?
A. Complications may include infection, abnormal nail growth (onychodystrophy), and recurrence of the exostosis if the excision was incomplete.
Q. Can Subungual Exostosis be prevented?
A. Preventing Subungual Exostosis involves avoiding trauma or excessive irritation to the toenail, as well as proper foot care and wearing appropriate footwear.
Q. What is the prognosis after Subungual Exostectomy?
A. The prognosis is generally excellent, with most patients experiencing pain relief and improved foot function, and a low risk of recurrence if the excision is performed properly.
Summary and Takeaway
Subungual exostosis is a benign yet potentially troublesome condition that can significantly affect the comfort and appearance of the toenail. While it is relatively rare, early diagnosis and surgical excision can effectively address the condition, providing pain relief and restoring normal foot function. With proper care and thorough excision, the prognosis is excellent, and recurrence is unlikely. If you suspect you have subungual exostosis, consult with a healthcare provider for diagnosis and treatment options to prevent complications and improve long-term outcomes.
Clinical Insight & Recent Findings
A recent study reported a rare case of early postoperative recurrence of subungual exostosis in a 13-year-old patient. Just four weeks after surgical removal of the bony growth, the lesion reappeared and grew rapidly—reaching several times its original size within three months. The researchers documented, for the first time, the detailed radiographic progression of this recurrence.
They emphasized that incomplete excision and younger patient age may increase recurrence risk, highlighting the importance of thorough curettage during surgery and close postoperative monitoring to ensure complete recovery. (“Study on rapid postoperative recurrence of subungual exostosis – see PubMed.“)
Who Performs This Treatment? (Specialists and Team Involved)
Orthopedic surgeons specializing in foot and ankle surgery typically perform subungual exostectomy. In some cases, a multidisciplinary team, including physical therapists and pain management specialists, may be involved in the preoperative and postoperative care.
When to See a Specialist?
If you have persistent pain, swelling, or deformity of the toenail, it is important to consult a specialist. Early diagnosis and treatment can prevent complications and improve the outcome.
When to Go to the Emergency Room?
Seek emergency care if you experience significant pain, infection, or an inability to move the toe following trauma. This could indicate a serious injury or complication.
What Recovery Really Looks Like?
Recovery after subungual exostectomy typically takes several weeks. The foot will be immobilized, and weight-bearing will be restricted. Full recovery may take up to 6 months, depending on the extent of the excision and the patient’s adherence to follow-up care.
What Happens If You Ignore It?
Ignoring subungual exostosis can lead to worsening pain, nail deformity, and potential complications like recurrence of the growth. Early intervention can prevent these issues.
How to Prevent It?
Preventing trauma and irritation to the toenail, as well as wearing proper footwear, can help reduce the risk of developing subungual exostosis. Regular foot care is also recommended.
Nutrition and Bone or Joint Health
A diet rich in calcium and vitamin D supports bone health and may help with recovery after surgery. Maintaining a healthy weight also reduces stress on the feet and lower extremities.
Activity and Lifestyle Modifications
After surgery, low-impact activities such as swimming or cycling may be recommended until the foot has healed fully. Avoiding excessive pressure on the toes during the recovery period will help ensure optimal healing.
Dr. Mo Athar
