The health specialist assigns and ICD-9 CM code E000.0 - E999.1 for classification of external causes of injury and poisoning. Since the patient suffered a fractured tibia while on a ski trip, it doesn't mean that he was injured while skiing. The health specialist will need to find the main cause of his fractured tibia, and in that, will be given ICD-9 code E000.0 - E999.1.