A 59-year-old female patient complains of burning pain in the plantar surface of her left foot for approximately 12 months. She reports that such discomfort is more intense when she first steps out of bed in the morning and improves with further activity. It also worsens at the end of the day. During physical examination, the referred pain is reproduced on passive dorsiflexion of the patient's toes and palpation of the plantar surface of her foot.

Picture 1: Lateral radiograph of the patient's left foot

Question:
Based on the clinical history and radiograph provided herein, which is the most likely diagnosis?