Review Question - QID 214384

A 64-year-old woman presents to her primary care provider with left wrist pain. She states that the pain has been present for nearly 1 month, and she does not remember any antecedent trauma except for a possible fall that she had recovered from without any complications. She has a history of type 2 diabetes mellitus that is controlled by diet and metformin. She has no other medical conditions and takes no other medications except for a multivitamin and calcium. On exam, her temperature is 98.2°F (36.8°C), blood pressure is 124/84 mmHg, pulse is 68/min, and respirations are 13/min. Her extremities are warm and well-perfused with intact distal pulses. She has full active range of motion of all joints in her left upper extremity, but she has tenderness to palpation between the first and third extensor compartments at the level of her wrist. Plain radiographs are taken and shown in Figure A. Which of the labeled in Figure A is at risk of avascular necrosis?