INTERMITTENT SOFT-TISSUE PAIN
A 50-year-old woman complains of unilateral, tearing, soft-tissue pain, usually in the posterior heel/Achilles area, with stretching. The problem has occurred on both sides but widely spaced in time. There is no pain on palpation and no redness, swelling, or weakness. Function is normal; no triggering event is apparent. The pain will last for weeks to months, then disappear completely.
Months later, the pain returns but only on one side at a time. Recently, the tearing pain occurred just below the knee—and only with pressure on the knee, e.g., with kneeling, but not with movement. This resolved spontaneously within a few weeks only to move to the dorsum and Achilles of one foot, again with stretching only. Blood chemistries, a complete blood count, and thyroid-stimulating hormone are normal. The patient has a history of depression and Hashimoto’s thyroiditis. She is currently taking venlafaxine (Effexor XR), bupropion (Wellbutrin XR), and thyroxine (Levoxyl). Your thoughts?
—Holly A. Johnson, MD, Charlottesville, Va.
I think the ankle and knee processes are unrelated and mechanical in nature rather than reflective of an underlying systemic disease. The knee pain with kneeling could be related to a prepatellar bursitis, an infrapatellar tendinitis, or, less likely, to a popliteal cyst that hurts when compressed. My first thought for the ankle pain is Achilles tendinitis, although the lack of tenderness and swelling is not consistent with this. Pain in the Achilles tendon area can also be due to repetitive strain (such as that which occurs in recreational athletes), improper footwear, or prolonged standing on concrete floors.
A tendon xanthoma (from hypercholesterolemia) is possible if your patient has familial hypercholesterolemia, although most xanthomas are palpable on exam or lead to thickening of the Achilles tendon. Subtle structural problems, such as limb-length discrepancy, can also result in posterior ankle pain.
I would start my evaluation with plain films to rule out any sinister pathology and prescribe physical therapy and a trial of nonsteroidal anti-inflammatory drugs. If there is no improvement, refer her to a rheumatologist or orthopedist for a more detailed musculoskeletal evaluation.
—Susan Kashaf, MD, MPH (113-22)