Not necessarily. Researchers recently used a bone substitute called "hydroxyapatite" (HA) to fix wrist fractures in 25 patients. Forty percent of the patients were over age 60, and some had osteoporosis. In addition to HA, patients had their wrists stabilized from the outside with pins.
The results were excellent across the board. In this case, patients' age didn't affect surgery results. Talk with your doctor about your concerns. There may be extra measures you can take to ensure proper healing.