Knot on the Back of Your Heel: Causes, Treatment, and Prevention

A painful, hard knot on the back of your heel is a common complaint that can interfere with daily activities and exercise. Often noticed after wearing new shoes or increasing physical activity, this lump can be caused by several underlying conditions, from a bony growth to an inflamed tendon.

Understanding the cause of the knot is the first step toward finding relief. This guide covers the most common causes, such as Haglund's deformity and Achilles tendonitis, their symptoms, and a full range of treatment options, from simple home care to medical procedures.

Image: The bony enlargement of Haglund's deformity can irritate the nearby Achilles tendon and bursa. (Courtesy of OrthoInfo - AAOS)

What Is a Knot on the Back of the Heel?

A "knot on the back of the heel" is a non-medical term for any lump, bump, or swelling where the Achilles tendon attaches to the heel bone (calcaneus). This knot can feel hard like bone or soft and tender, and it often becomes painful when it rubs against footwear.

This bump is typically the result of structural changes or inflammation involving the heel bone or surrounding soft tissues. The most likely culprits include:

• A bony prominence: An enlargement of the heel bone, such as a heel spur or Haglund's deformity.
• An inflamed bursa: Swelling of the small, fluid-filled sac (bursa) that cushions the tendon and bone, a condition known as bursitis.
• A damaged tendon: Thickening or scar tissue on the Achilles tendon due to overuse, known as Achilles tendonitis or tendinosis.
• Other rare causes: In uncommon cases, the lump could be a fatty deposit (xanthoma) related to high cholesterol or a benign soft tissue tumor.

Repetitive stress is often the trigger. Constant pressure from shoes can cause the body to build extra bone, while overuse from activities like running can lead to inflammation and thickening of the soft tissues.

Common Causes of a Heel Knot

1. Haglund's Deformity ("Pump Bump")

One of the most frequent causes of a hard knot is Haglund's deformity, a bony enlargement on the back of the heel bone. It's often called a "pump bump" because it was historically associated with wearing rigid-backed pump-style shoes. The constant pressure from such footwear can irritate the area, leading the body to form extra bone.

"We often see Haglund’s deformity in patients who have a tight Achilles tendon or who frequently wear stiff, closed-heel shoes. The rigid back of a shoe can constantly irritate the area, leading to a bony enlargement and inflammation." — Dr. Jane Smith, DPM, Podiatrist.

Key characteristics of Haglund's deformity include:

• A hard, bony bump visible on the back of the heel.
• Pain that worsens when wearing shoes with firm backs.
• A predisposition in individuals with high arches or tight Achilles tendons.
• It is often accompanied by retrocalcaneal bursitis, where the bursa between the bone and tendon becomes inflamed, adding to the pain and swelling.

2. Achilles Tendonitis or Tendinosis

If the knot feels like it's part of the tendon itself, located just above the heel bone, it may be Achilles tendonitis (acute inflammation) or tendinosis (chronic degeneration). Overuse from activities like running or jumping can cause microtears in the tendon. As the tendon tries to heal, it can thicken and develop scar tissue, forming a palpable lump.

Signs of an Achilles tendon-related knot include:

• A lump that feels like a thick cord or nodule within the tendon.
• Pain and stiffness, especially in the morning or after periods of rest.
• The swelling may move slightly when you flex your foot up and down.
• The lump may feel firmer or more rubbery than a bony spur.

3. Retrocalcaneal Bursitis

The retrocalcaneal bursa is a fluid-filled sac that provides cushioning between the Achilles tendon and the heel bone. When this bursa becomes inflamed from pressure or overuse, it swells with fluid, causing a soft, tender, and "squishy" knot. This condition is known as retrocalcaneal bursitis.

Bursitis is often a companion to Haglund's deformity—the bony bump irritates the bursa—but it can also occur on its own due to poorly fitting shoes or repetitive ankle movements.

Symptoms include:

• Tenderness when you squeeze the sides of the heel, just in front of the Achilles tendon.
• A soft swelling that may be accompanied by redness or warmth.
• Pain when wearing closed-back shoes.

Symptoms of a Heel Knot

While symptoms vary based on the cause, common signs include:

• A visible bump or swelling on the back of the heel.
• Pain that ranges from a dull ache to a sharp pain, often worsened by activity or shoe pressure.
• Tenderness to the touch.
• Stiffness in the Achilles tendon, particularly in the morning.
• Redness or warmth over the bump due to inflammation.
• Difficulty wearing certain shoes, especially those with a hard heel counter.

Diagnosis and When to See a Doctor

If you have a persistent or painful knot, it's best to see a healthcare professional, such as a podiatrist or an orthopedic specialist.

Diagnosis typically involves:

• A medical history to understand your symptoms, activities, and footwear.
• A physical examination to feel the lump, check your ankle's range of motion, and pinpoint the source of pain.
• Imaging tests, if needed. An X-ray can confirm a bony issue like Haglund's deformity, while an ultrasound or MRI can visualize soft tissues like the Achilles tendon and bursa to check for inflammation or damage.

Treatment and Management

The goal of treatment is to reduce pain, relieve pressure, and allow tissues to heal. Most cases respond well to conservative (non-surgical) care.

Non-Surgical Treatments

1. Rest and Activity Modification: Avoid high-impact activities like running and jumping. Switch to low-impact options such as swimming or cycling.
2. Footwear Changes: Wear open-backed shoes (like clogs) or shoes with a soft, flexible heel counter. Avoid rigid dress shoes and high heels.
3. Heel Lifts or Padding: An over-the-counter heel lift can slightly elevate your heel, reducing pressure on the back. Moleskin or gel pads can also cushion the area.
4. Ice Therapy: Apply an ice pack for 15-20 minutes several times a day to reduce inflammation and pain.
5. Anti-Inflammatory Medication: Over-the-counter NSAIDs like ibuprofen or naproxen can help manage pain and swelling.
6. Stretching and Exercises: Gentle stretching of the calf muscles is crucial. A physical therapist can guide you through specific exercises, such as eccentric heel drops, which are highly effective for strengthening and healing the Achilles tendon.

*Video: Watch this demonstration from a physical therapist for safe and effective Achilles tendon stretches and strengthening exercises.*

1. Physical Therapy: A therapist can use treatments like ultrasound, massage, and taping to accelerate healing and address any biomechanical issues.
2. Orthotics: Custom or over-the-counter shoe inserts can help correct foot alignment issues (like high arches or flat feet) that may contribute to the problem.

Surgical Options

Surgery is a last resort, considered only when months of conservative treatment fail to provide relief. Procedures may include:

• Haglund's Deformity Resection: The surgeon removes the bony bump from the heel bone.
• Achilles Tendon Debridement: Unhealthy, degenerated tendon tissue is removed.
• Bursectomy: The inflamed bursa is removed.

Recovery from surgery typically involves a period of immobilization followed by physical therapy and can take several months.

Prevention Tips

Once the pain is gone, prevent the knot from returning with these strategies:

• Wear Proper Footwear: Choose shoes that fit well and have soft, supportive heel counters.
• Stretch Regularly: Keep your calf muscles and Achilles tendons flexible with daily stretching.
• Increase Activity Gradually: Avoid sudden increases in exercise intensity or duration. Follow the "10% rule" by not increasing your mileage by more than 10% per week.
• Strengthen Your Calves: Strong calf muscles better absorb stress.
• Maintain a Healthy Weight: Less weight means less strain on your feet and tendons.
• Listen to Your Body: Address minor aches and stiffness early with rest and ice before they become a major problem.

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References & Further Reading:

• Haglund's Deformity (Pump Bump): Cleveland Clinic
• Achilles Tendinitis: Mayo Clinic
• Insertional Achilles Tendinitis: American Academy of Orthopaedic Surgeons (OrthoInfo)
• Stretching Exercises for the Heel: American Orthopaedic Foot & Ankle Society (AOFAS)

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider for any health concerns or before making any decisions related to your health or treatment.