Hypothesis 2:

Forced extraction with calf chains and a calf pull during difficult parturition is a common cause of injury to the forelimbs of calves.  Typically the chains are wrapped around the fetlock joint and pressure is applied to the metacarpus to extract the calf from the birth canal.  A fracture of the metacarpus is a common sequelae of difficult deliveries.  The fracture expected is described in hypothesis 1.  A sequestrum could possibly have formed and is also discussed in hypothesis 1.  This explains the draining tract and the exudate.
The hyperextension of the left toes could be due to a congenital deformity.  The hyperextension deformity is a result of lack of adequate flexor tone.  Due to the permanent contracture of the extensor tendons, they have become thick and fibrous.  This explains the inability of the calf to straighten its joint and the presence of the fibrous bands of tissue.  If a congenital deformity is present, the thick bandage that was used to wrap the leg was contraindicated.