A 24-year-old man comes to the office due to severe pain in the posterior aspect of the right foot that interferes with walking. For the last several months, the patient has also experienced a dull backache and morning stiffness that is relieved by over-the-counter ibuprofen. Family history is insignificant, and he does not use tobacco, alcohol, or illicit drugs. Which of the following is the most probable location of the pathologic process responsible for this patient's foot pain?

Question

A 24-year-old man comes to the office due to severe pain in the posterior aspect of the right foot that interferes with walking.  For the last several months, the patient has also experienced a dull backache and morning stiffness that is relieved by over-the-counter ibuprofen.  Family history is insignificant, and he does not use tobacco, alcohol, or illicit drugs.  Which of the following is the most probable location of the pathologic process responsible for this patient's foot pain?

Quizplus · Accepted Answer

11ec160b_3b61_d001_9249_375be03f4751_MD0001_00 This patient has inflammatory back pain (ie, onset at age <40, chronic/insidious pain and stiffness that are better with activity and worse with rest), which is likely due to ankylosing spondylitis (AS). In AS, the inflammatory process is thought to originate in the gut due to an altered intestinal biome and defects in the mucosal barrier; the resulting inflammatory response leads to upregulation of cytokines (primarily tumor necrosis factor-alpha and IL-17), with activation of innate immunity and migration of immune cells to the skeleton. The resulting skeletal manifestations are most prominent in areas of mechanical stress, primarily at the insertions of tendons, ligaments, and joint capsules (collectively, entheses) on bone. Enthesitis is a relatively specific finding in AS and other forms of spondyloarthritis and is characterized by local pain, tenderness, and possible swelling. Common clinical syndromes include Achilles tendinitis, plantar fasciitis, and dactylitis ("sausage digits"). Achilles tendinitis affects the site of insertion of the Achilles tendon on the calcaneus and typically presents with severe pain at the posterior aspect of the heel. (Choices A and D) Peripheral arthritis is common in AS. In these cases, the inflammatory process largely affects the articular cartilage and subchondral bone; synovial involvement is typically minor. However, the pain is typically felt within the ankle (eg, tibiotalar and subtalar arthritis) rather than at the posterior aspect of the foot. (Choice B) Injury to the cortical bone of the calcaneus can occur acutely due to a high-velocity fall or crush injury or chronically due to a stress fracture in athletes who run on hard surfaces. This patient's inflammatory back pain makes enthesitis a more likely cause of his heel pain. (Choice C) Retrocalcaneal bursitis causes pain and swelling at the posterior heel near the insertion of the Achilles tendon. It is usually caused by overuse and often occurs in association with Achilles tendinopathy. However, it is significantly less common than enthesitis as a cause of posterior heel pain in AS. Educational objective: Enthesitis (inflammation at the bony insertions of tendons, ligaments, and joint capsules) is a prominent manifestation of spondyloarthritis (eg, ankylosing spondylitis). Common clinical syndromes include Achilles tendinitis, plantar fasciitis, and dactylitis. Achilles tendinitis affects the site of insertion of the Achilles tendon on the calcaneus and presents with severe pain at the posterior aspect of the foot. __________ References: Review: enthesitis: new insights into pathogenesis, diagnostic modalities, and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/26473401)

A 24-Year-Old Man Comes to the Office Due to Severe