A 38-year-old woman from Bangalore presents to the emergency department with acute onset weakness of the right foot (inability to dorsiflex the ankle or evert the foot) and foot drop. She reports tripping over a low step 2 days ago and falling directly on the lateral aspect of her right knee. On examination, there is tenderness over the fibular head region. Sensation is preserved over the medial sole of the foot but diminished over the lateral leg and dorsum of the foot. Ankle plantarflexion and toe flexion are intact. What is the most likely diagnosis?