Final answer:
The next best step in management is orthopedic consultation.
Step-by-step explanation:
The next best step in the management of this patient with severe, acute left knee pain and inability to bear weight is d) Orthopedic consultation.
Based on the clinical presentation, including the mechanism of injury and inability to actively extend the knee, it is important to evaluate for possible ligamentous or meniscal injuries. An orthopedic consultation can provide a comprehensive evaluation and determine the need for imaging studies such as MRI to assess the extent of the injury and guide further management.
Additional interventions such as angiogram (a), closed reduction (b), or computed tomography scan (c) are not typically the next best step in this scenario.