Brad, a 35-year old male accountant, presents to the primary care office with a chief complaint of “sudden left ankle pain while playing basketball” the day before. While jumping up to catch a rebound, he says he felt as if he was kicked behind the ankle. He heard a “pop” of his left ankle and was unable to continue due to the pain. Since the onset of pain, Brad has had difficulty with weightbearing and climbing stairs.

In regard to his past medical history, Brad has had hypertension for three years. His medications include hydrochlorothiazide 10 mg three times a day and a once-a-day multivitamin. He is married, has three children and does not smoke or drink. Brad is happy at his job but states it is very stressful. Brad has played basketball on weekends for the past five years to alleviate the stress. He notes that he was more physically active in his 20s when he lifted weights two to three times a week and ran 10 to 12 miles a week.

What The Physical Exam Reveals
The physical examination shows a well-developed, well-nourished man in apparent distress. His vital signs include a sitting blood pressure of 132/84, a heart rate of 82 beats per minute with regular rate and rhythm, and respiration of 18 breaths per minute. He weighs 222 lbs. with clothes and is 6’1” without shoes.

During the physical exam, we note tenderness of the posterior aspect of the left ankle with an associated palpable depression. There is weakness of plantarflexion of the left foot and a positive Thompson test. Lower extremity sensory testing is equal bilaterally to light touch with sharp and dull sensation. Deep tendon reflexes are +2/4.

Based upon the patient history and physical examination, which of the following is the most likely diagnosis?

A. Plantar fasciitis
B. Morton’s neuroma
C. Hallux valgus
D. Achilles tendon rupture

Key Insights Into The Differential Diagnosis
A. Plantar fasciitis is not the correct answer. Plantar fasciitis is an inflammation with an origin at the longitudinal ligament, the principal ligament that forms the arch of the foot. Plantar fasciitis is the most common cause of heel pain.¹ Plantar fasciitis accounts for an estimated 11 to 15 percent of all foot symptoms.

Risk factors include obesity, prolonged standing, pes planus, reduced dorsiflexion and heel spurs. When patients have plantar fasciitis, they commonly complain of pain on the bottom of their heel.

In regard to plantar fasciitis, the physical examination will reveal a gradual onset of pain in the inferior heel that becomes worse with the first steps in the morning or after a period of inactivity. This pain subsides with activity but becomes worse toward the end of the day. You may find localized tenderness at the anteromedial aspect of the inferior heel.

Radiographs of the ankle may exclude stress fracture of the calcaneous and a heel spur. A bone scan is useful in distinguishing plantar fasciitis from calcaneal stress fracture.

Treatment goals include reducing inflammation in the longitudinal arch and improving mechanics of the heel and ankle. Physical therapy includes ice, heat, massage and strengthening and stretching exercises of the calf and foot muscles.
Additional treatment may include combining reduced weightbearing with padded arch supports, non-steroidal antiinflammatory drugs (NSAIDs) and/or local steroid injection. One may consider surgical options for patients who have persistently severe symptoms despite conservative treatment.

B. Morton’s neuroma is not the correct answer. Morton’s neuroma is a chronic inflammation/irritation of the digital nerve between the metatarsophalangeal (MPJ) heads, most commonly between the third and fourth toes. A patient may commonly complain of numbness in the toes or sharp pain between the toes. The cause of the interdigital neuroma is unknown. However, it does occur more frequently in women and high fashion footwear is a risk factor.

Pathologic changes involve degeneration of nerve fibers which is consistent with nerve entrapment. Patients may complain of localized pain in the metatarsal head of the third and fourth toes. They may indicate increased pain when walking, and that the pain is relieved by rest and removing the shoe. Loss of sensation along inner aspects of the adjacent two toes is an indication of an advanced case of an interdigital neuroma.

While radiographs are not helpful in the diagnosis of an interdigital neuroma, they may reveal pathology of the MTP joint. Clinicians may use ultrasound to evaluate the presence of nerve enlargement.

Treatment goals include reducing pressure over the nerve and eliminating the associated inflammation. Conservative treatment may include a wider, soft-soled shoe to accommodate the foot, avoiding mediolateral compression and lowering the heel.

Bear in mind that NSAIDs are ineffective for this condition due to poor penetration into the affected tissues. One may consider a local steroid injection for cases that persist after four to six weeks of treatment. However, be aware that steroid injection can lead to local fat atrophy, which may cause diminished padding under the metatarsal heads, local skin thinning and discoloration. If conservative treatment fails, surgical excision of the nerve is indicated.

C. Hallux valgus is not the correct answer. Hallux valgus is a bony prominence and abnormal angle of the great toe. Intrinsic causes of hallux valgus deformity include pes planus and metatarsus primus, rheumatoid arthritis (RA), chronic tightness of the Achilles tendon, connective tissue disease and cerebral palsy. The most common cause is poorly fitted shoes. The patient may complain, “I cannot get a pair of shoes to fit comfortably now” and “My big toe aches all the time.”

Asymmetric pressure over the articular cartilage leads to cartilage loss, angulation of the joint and gradual subluxation of the extensor tendons. The asymmetrical wear and tear on the joint caused by narrow, toe-box shoes leads to the typical valgus deformity.

When it comes to these patients, the physical examination typically reveals a tender and enlarged first MTP joint. This tenderness occurs along the medial joint line or over the entire joint if an acute arthritic flare is present. Joint enlargement is due to subluxation, osteophyte formation and swelling. Passive range of motion can lead to crepitation, pain and decreased range of motion of the first MTP.

Radiographs will reveal asymmetric narrowing of articular cartilage, bony osteophyte formation, subchondral bony sclerosis and subchondral cyst formation. Treatment goals include reducing inflammation, preventing arthritis deterioration and retarding valgus deformity.

Wide toe-box shoes, toe spacers and adhesive pads are the treatments of choice. Non-steroidal antiinflammatory drugs may be helpful. A local intraarticular steroid injection may be helpful in persistent cases. Consider a referral to an orthopedist if symptoms persist or if the deformity is great.

D. Achilles tendon rupture is the correct answer. Achilles tendon ruptures occur most often as an acceleration injury such as pushing off or jumping. A patient will typically complain of feeling like he or she was “kicked” or “shot” behind the ankle. The majority of patients who sustain the injury are men — between the ages of 30 to 50 — who participate in sports activities. The male to female ratio is 20 to 1.²

Fluoroquinolone antibiotics and direct steroid injections have been linked to an increased risk of Achilles tendon rupture. The mechanical cause of the injury is active, forceful plantarflexion associated with athletic movements.
Physical examination findings include a palpable depression over the area of the tendon rupture, weakness of plantarflexion and a positive Thompson test (squeezing the calf of the affected side without eliciting passive plantarflexion).

A lateral radiograph of the ankle may reveal a Kager’s triangle. The triangle is located in the retromalleolar region. It is defined anteriorly by the posterior aspect of the tibia and posteriorly by the Achilles tendon, with the base being the proximal aspect of the calcaneus. The space contained within this triangle is filled with fatty tissue and produces a well defined area. This space will become serrated and indistinct when the Achilles tendon is ruptured.

Ultrasound will help define the site of the tear. Magnetic resonance imaging (MRI) can confirm the diagnosis. There is no consensus for treating Achilles tendon ruptures in the literature. However, treatment options may include bracing, cast immobilization or surgical management.

Editor’s note: For a related article, see “What You Should Know About Hallux Limitus” in the May/June 2007 issue.
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