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When Heel Pain Results From Other Soft Tissue Pathology

One of the most common patient complaints in podiatry offices, heel pain may result in significant discomfort and, at times, lead to disability. While plantar fasciitis is typically the cause, one cannot overlook other soft tissue, osseous and systemic disorders that can cause heel pain. With this in mind, this author reviews other potential etiologies of heel pain and key diagnostic findings that may assist physicians in reaching an accurate diagnosis. 

Plantar fasciitis is by far the most common cause of heel pain presenting in the outpatient setting with millions suffering from this condition each year. This condition accounts for 10 percent of running-related injuries and 11 to 15 percent of all foot symptoms requiring professional medical care.1 Given the extensive prevalence of this condition, it is not uncommon for physicians to overlook other potential causes of heel pain. 

Plantar fasciitis involves inflammation and microtearing of the plantar fascia along its course, which can create a chronic local inflammatory cycle. Plantar fasciitis is most commonly painful to palpation in the medial heel region at the level of the plantar fascia attachment to the medial calcaneal tubercle. The patient’s history will typically reveal the classic symptom of pain with the first few steps in the morning or after a prolonged period of rest. The vast majority of these cases resolve with conservative treatment modalities of stretching, anti-inflammatory medication, shoe gear modifications, orthotics or a combination of these. 

If the patient’s pain is not localized to the attachment of the plantar fascia or if it does not resolve with conservative treatment, this should lead the practitioner to consider other possible causes of the patient’s pain. It is not uncommon for podiatrists to be guilty of representative bias in which the practitioner looks for the classic presentation of a disease, plantar fasciitis in this case, and misses the variant or atypical pattern of a different but similar disease.2 Young podiatrists are typically more prone to representative bias and this can lead to frustration for both the clinician and the patient.2 Even worse, it can lead to improper conservative or surgical decision making, which may subsequently lead patients down the route of seeking a second opinion due to continued pain. It is critical for foot and ankle specialists to consider the wide range of possible differential diagnoses before coming to a conclusion on the etiology of the pain. 

A short list of these alternative etiologies includes: 

• lumbosacral radiculopathy; 

• plantar fascia rupture; 

• tarsal tunnel syndrome; 

• Baxter’s nerve entrapment; and 

• fat pad atrophy. 

Accordingly, let us take a closer look at these potential etiologies and review different clinical exam and diagnostic fifindings that are common with each. There are also certain clues within the patient history that can lead us to an accurate diagnosis. 

Key Considerations With Lumbosacral Radiculopathy 

Among the causes of heel pain, nerve entrapment is frequently underreported. Researchers have noted an association between radiculopathy and plantar heel pain secondary to nerve entrapment, specifically at the L5 to S1 level.3 Upton and McComas initially described double crush syndrome in patients with carpal tunnel syndrome and lesions of the ulnar nerve around the elbow in association with more proximal cervical root lesions.3 The same double crush phenomenon can occur between the lumbosacral area of the spine and the tarsal tunnel, manifesting itself as plantar heel pain. 

Providers can begin to uncover a radiculopathy that may be contributing to heel pain by conducting a thorough history and physical exam. This should include questioning the patient on any history of back pain or injury as well as thorough neurosensory testing. Often times, these patients can not completely pinpoint their area of pain and it may seem more diffuse than the classic presentation of plantar fasciitis. If there is suspicion for some sort of radiculopathy, one would be well served to refer the patient for electromyography (EMG) and nerve conduction velocity tests that can lead to a more definitive diagnosis. 

Once one establishes a diagnosis of a lumbosacral radiculopathy, treatment typically depends on the severity of the case. Conservative care options consist of physical therapy, shoe gear modification and medication (such as gabapentin) to treat neuropathic pain. If these options fail, the next step would be to refer these patients to an orthopedic spine specialist. Achieving the proper diagnosis in these patients, rather than assuming they may have chronic and refractory plantar fasciitis, can help them receive prompt and appropriate treatment in an effort to reduce their pain. 

Plantar Fascia Rupture: What You Should Know 

While acute tears of the plantar fascia are relatively uncommon, they can occur, especially in patients with chronic plantar fasciitis. Tears can also occur more spontaneously in athletes or more active patients although this is less common in our experience. In the setting of chronic plantar fasciitis, patients who receive multiple corticosteroid injections are at greater risk of an acute tear due to weakening and atrophy of the plantar fascia ligament.4 In this instance, taking a thorough history is important as patients can typically recall sudden onset pain following athletic activity or a fall. Often times, in cases of an acute rupture, the patient will present with an antalgic gait and complain of severe pain that is worse with weightbearing and does not resolve with continued activity. 

Diagnosis of an acute rupture of the plantar fascia is typically clinical in nature. However, imaging modalities such as ultrasound and magnetic resonance imaging (MRI) are useful tools when attempting to rule out other pathology and help the practitioner come to a more definitive conclusion. On ultrasound, one will observe a complete or partial interruption of the plantar fascia with hypoechoic tissue at the site of rupture. An MRI will show complete or partial interruption of the plantar fascia, an intermediate T1 and high T2 signal at the site of rupture, and edema within the adjacent soft tissues. Magnetic resonance imaging is also useful in assessing the other surrounding ligaments and tendons, and can evaluate for the presence of potential reactive bone changes within the calcaneus. 

The vast majority of patients with an acute rupture of the plantar fascia respond well to conservative treatment in our experience. A period of rest combined with immobilization over a period of three to four weeks and non-steroidal anti-inflammatory medication is often indicated. Following this period of rest, patients typically have great improvement in their pain level, particularly those who suffered with chronic plantar fasciitis prior to rupture. Operative treatment is rarely necessary unless patients do not respond to conservative treatment. In this case, the foot and ankle surgeon may elect to operatively release the remainder of the plantar fascia in the setting of a partial rupture. 

When One Suspects Tarsal Tunnel Syndrome 

Tarsal tunnel syndrome is a rare entrapment neuropathy that involves compression of the posterior tibial nerve or one of its distal branches as it courses beneath the flexor retinaculum (laciniate ligament) along the medial heel.5 Pain, burning, numbness and tingling in the heel that may radiate to the plantar aspect of the foot and into the toes may be present in patients with tarsal tunnel syndrome. However, this condition is often underdiagnosed, especially in patients with diabetes who may already have symptoms of peripheral neuropathy or lumbar radiculopathy. 

It is important to consider conditions that may compress or irritate the tibial nerve at the tarsal tunnel. Potential causes may include previous trauma to the area; pes planus that may stretch the contents of the tarsal tunnel; morbid obesity; space-occupying lesions (ganglion cysts, varicose veins, tumors, etc.); tendonitis in an active person from repetitive stress after running or walking; or increased edema after excessive standing. In a patient with chronic tarsal tunnel syndrome, there may be weakness of the intrinsic flexors and toe abductors of the foot. In the more advanced cases, one may note muscle atrophy. 

Once again, a comprehensive clinical examination is key to differentiating tarsal tunnel syndrome from other soft tissue causes of heel pain. Symptoms will generally be unilateral. Besides palpating for a space-occupying lesion and percussing the nerve and its branches around the tarsal tunnel in search of a positive Tinel’s sign, the practitioner should also dorsiflex and evert the foot for five to 10 seconds, hoping to be able to reproduce the paresthesia the patient may be experiencing. Be sure to have the patient stand and ambulate during the encounter to observe for any excessive pronation, supination or hindfoot malalignment that may give you clues as to the root of the cause. 

Magnetic resonance imaging is an adjunctive imaging modality that can inspect for any soft tissue abnormality in or around the tarsal tunnel. However, to confirm a tibial nerve lesion, make sure to refer the patient to a neurologist for sensitive sensory and motor nerve conduction velocities (NCVs) as well as electromyography if initial conservative treatment fails. The practitioner would look for increased distal latency in the nerve conduction velocity as well as fibrillation potentials that indicate axonal injury to the muscles innervated by the tibial nerve distal to the tarsal tunnel. 

Initial treatment for the patient may involve the use of oral non-steroidal anti-inflammatory drugs (NSAIDS) for initial reduction of inflammation along with several weeks of rest, ice and elevation of the involved foot. The practitioner could attempt to address the mechanism of injury by utilizing custom orthotics to correct foot posture and provide better support of the foot with ambulation. If the patient wears boots to ambulate or while he or she is at work, padding of the area could prove beneficial to reduce pressure and irritation to the nerve. If the patient does not improve with this measure, the next step would be to immobilize the foot for four to six weeks with the use of a CAM boot or splint along with corticosteroid injections and possible referral to physical therapy. Depending on the success of the conservative treatment and the severity of the results from the diagnostic studies, the practitioner should consider a local nerve block before considering surgical treatment. If the pain ameliorates or completely subsides with the injection, then one might find success with subsequent decompression of the tibial nerve at the tarsal tunnel and its branches. Finally, if there is a space-occupying lesion present within the tarsal tunnel or adjacent area, it would be prudent to remove the lesion to reduce the pressure around the nerve. 

When A Patient Suffers From Baxter’s Nerve Entrapment 

Baxter’s nerve entrapment is a condition podiatrists typically consider after the patient has not benefitted much from aggressive conservative treatment. It involves compression or entrapment of the first branch of the lateral plantar nerve. This condition tends to be underdiagnosed and is often mistaken for plantar fasciitis due to the patient typically presenting with pain on the plantar medial aspect of the heel. On the contrary, Baxter’s nerve travels between the abductor hallucis muscle and the medial calcaneal tuberosity, running medial to lateral on the heel to finally innervate the abductor digiti minimi muscle.6,7 Some predisposing factors include obesity, overpronation, hypertrophy of the abductor hallucis muscle at its origin or increased inflammation secondary to chronic plantar fasciitis. 

Both tarsal tunnel syndrome and Baxter’s neuritis share many symptoms I previously mentioned such as a deep ache and paresthesia, but without the sensory deficits. Accordingly, it is important to rule out plantar fasciitis, tarsal tunnel entrapment and other calcaneal pathology. 

One should palpate the proximal and distal plantar fascia, and the origin of the abductor hallucis muscle where the nerve travels beneath it. Palpate and percuss the tibial and medial calcaneal nerves, and perform the side to side heel squeeze test to see if this elicits symptoms. During manual muscle testing, include the abductor digiti minimi in your assessment and look for the patient’s ability to abfiduct the fifth digit. If you note weakness or inability to perform this movement, then consider referring the patient for medical imaging and further testing. 

Radiographs for this condition will not help much in the diagnosis. The use of EMG/NCV studies may help but MRI is the most accurate confirmatory imaging study. During mild stages of Baxter’s neuritis, look for inflammation around the proximal aspect of the plantar fascia that may be causing pain from compression of the nerve. In advanced cases in which there is moderate to severe motor weakness of the abductor digiti minimi muscle, be on the lookout on MRI for decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images with fatty infiltration of the abductor digiti minimi, indicating decreased muscle volume and atrophy. 

In most cases, conservative care is the mainstay treatment for Baxter’s neuritis. The approach is similar to what one may attempt for treating plantar fasciitis. The initial goals are to decrease the pain with analgesic medication, reduce the inflammation around the area with oral NSAIDs or a corticosteroid injection, emphasize equinus stretching via bracing and remove any aggravating factor that may be causing nerve irritation with padding or foot orthotics. If conservative treatment fails and one notices atrophy of the abductor digiti minimi muscle, then complete surgical neurolysis of Baxter’s nerve is indicated. 

Pertinent Pointers About Fat Pad Atrophy And Heel Pain 

This type of heel pain is more common in the obese or elderly populations above 65 years of age. These patients will present with deterioration or reduction of the integrity of the adipose tissue, which provides cushioning and shock absorption to the heel.8 When describing the pain, patients relate a deep ache and tenderness at the center of the plantar heel that is more often bilateral.8 The pain tends to be more diffuse along the plantar heel in comparison to plantar fasciitis or nerve entrapments where the location of the pain can be more precise. These patients will complain of worsening symptoms after prolonged periods of standing and walking, and will relate having night pain with rest. 

During the comprehensive clinical examination, identify if there is thinning of the fat pad not only of the heel but also at the forefoot underneath the metatarsals, where one can easily palpate bony prominences. Also, work your way around the heel, avoiding the point of maximum tenderness to try and rule out other possible soft tissue causes of heel pain like plantar fasciitis or nerve entrapment. Then try to reproduce the symptoms with direct palpation to the central aspect of the heel. 

With experience, every practitioner will develop his or her own algorithm for treating conditions but fat pad atrophy is one that may be more straightforward than others. Initially ask the patient about the possibility of modifying daily activity to decrease periods of standing or ambulating. Also emphasize proper shoe gear with the possible use of accommodative orthotics with plenty of shock-absorbing material in order to decrease pressure to the affected area. Another alternative to supportive orthotics is the use of heel cups if there is no other underlying biomechanical factor such as a cavus foot. 

In Conclusion 

Heel pain is one of the most common problems we see as podiatrists. However, it is important to realize there are several different causes. It is paramount for the physician to avoid representative bias and perform a proper workup of each patient rather than jumping to the most common diagnosis of plantar fasciitis. Most importantly, taking a detailed patient history can lead the physician down the proper route toward an accurate conclusion. 

Additionally, utilizing a solid physical exam as well as diagnostic imaging and testing when indicated can help clear up the clinical picture, especially for those patients who do not exhibit the classic presentation, or signs and symptoms of plantar fasciitis. Finally, appropriate and timely treatment is critical in order to have good outcomes and get patients back on their feet. Most of the other causes of heel pain we have outlined in this article do not require surgical intervention and do respond to aggressive conservative treatment modalities.  

Dr. DeHeer is the Residency Director of the Ascension St. Vincent Hospital Podiatry Program in Indianapolis. He is a Fellow of the American College of Foot and Ankle Surgeons, a Fellow of the American Society of Podiatric Surgeons, and a Fellow of the American College of Foot and Ankle Pediatrics. Dr. DeHeer is also a Fellow of the Royal College of Physicians and Surgeons of Glasgow, and a Diplomate of the American Board of Podiatric Surgery. 

Dr. Nichols is a third-year podiatric surgery resident at Ascension St. Vincent Hospital in Indianapolis. 

Dr. Amaro is a second-year podiatric surgery resident at Ascension St. Vincent Hospital in Indianapolis. 

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By Patrick DeHeer, DPM, FACFAS, Josh Nichols, DPM and Jorge Amaro, DPM
References

1. Buchanan BK, Kushner D. Plantar Fasciitis. StatPearls [Internet]. Available at: https:// www.ncbi.nlm.nih.gov/books/NBK431073/ . Updated June 7, 2020. Accessed September 29, 2020. 

2. Shapiro J. Practice perfect. Vocabulary for educators. Present Podiatry News. Available at: https://podiatry.com/news/488/Practice- Perfect-721-Vocabulary-for-Educators . Published August 25, 2020. Accessed September 29, 2020. 

3. Upton AR, McComas AJ. The double crush in nerve entrapment syndromes. Lancet. 1973;302(2):359-362. 

4. Tatli YZ, Kapasi S. The real risks of steroid injection for plantar fasciitis, with a review of conservative therapies. Curr Rev Musculoskelet Med. 2009;2(1):3-9. 

5. Doneddu PE, Coraci D, Loreti C, Piccinini G, Padua L. Tarsal tunnel syndrome: still more opinions than evidence. Status of the art. Neurol Sci. 2017;38(10):1735-1739. 

6. Sarrafian SK. Nerves. In: Sarrafian SK (ed). Anatomy of the Foot and Ankle. 2nd ed. Philadelphia: Lippincott, Williams and Wilkins; 1993: 381. 

7. Beltran LS, Bencardino J, Ghazikhanian V, Beltran J. Entrapment neuropathies III: Lower limb. Sem Musculoskel Radiol. 2010;14(05):501-511. 

8. Yi TI, Lee GE, Seo IS, Yoon TH, Kim BR. Clinical characteristics of the causes of plantar heel pain. Ann Rehabil Med. 2011;35(4):507-513. 

Additional Reference 

f9. Toye LR. Baxter’s nerve (first branch of the lateral plantar nerve) impingement. Radsource. Available at: https://radsource.us/baxters-nerve . Published August 2012. Accessed October 14, 2020. 

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