In considering the residuals of injury, it is essential to trace the medical-industrial history of the disabled person from the original injury, considering the nature of the injury and the attendant circumstances, and the requirements for, and the effect of, treatment over past periods, and the course of the recovery to date. The duration of the initial, and any subsequent, period of total incapacity, especially periods reflecting delayed union, inflammation, swelling, drainage, or operative intervention, should be given close attention. This consideration, or the absence of clear cut evidence of injury, may result in classifying the disability as not of traumatic origin, either reflecting congenital or developmental etiology, or the effects of healed disease.