Compound fractures often become infected because of the exposure to deep seated systems in the body, like the tibia-fibula (lower leg), or femur (upper leg), it sounds-like, in this case. He has to pay especial-attention to the wound, as the effects of the opportunistic infection can become serious very quickly. I assume they have him on IV antibiotics, for a broad-spectrum antibiotic as a preventative measure.
Young people heal more-quickly than mature-aged adults. His family should ask plenty of questions about the process for repairing the damage, and any sequential issues which develop. There usually is a panel of MD's who consider the serious cases for the path of treatment of the patient, and that helps to prevent something being overlooked by a MD w/a lot of patients. Don't be afraid to ask for a consultation from another practitioner if you don't see progress in the healing as-expected. The HIPPA regulations the hospitals have to follow make them very responsive if you know the proper path to take in making a request for additional input. Requesting a meeting for the patient and his family with a hospital administrator will light a fire under someone's butt if you don't think the patient's best interests are being addressed. Keep in-mind that things like staph infections are very common in hospitals, and the staff takes the preventative measures very seriously to combat those issues.