A 58-year-old woman with osteoporosis is admitted 3 days after a fall with a displaced fracture of the right proximal humerus. Intraoperative fixation with open reduction and internal fixation (ORIF) was performed. On postoperative day 2, she develops severe pain in the hand, swelling of the fingers, skin mottling, and a skin temperature drop of 3–4°C compared to the left hand. Radial and ulnar pulses are palpable. What is the most likely diagnosis?