A 32-year-old male construction worker sustains a crush injury to his right leg when a steel beam falls on him at the site. On arrival at the emergency department, there is a 4 cm laceration over the anterior tibia with visible bone protruding through the skin. The wound is heavily contaminated with soil and debris. Neurovascular examination reveals intact dorsalis pedis and posterior tibial pulses, and sensation is preserved. There is no evidence of compartment syndrome. What is the Gustilo classification of this fracture?