I'd replace the broken parts sewing new ones. This is how I'd proceed: I'd unstich and cut off the velcro keeping the dacron, than I'd sew a new dacron and velcro strip keeping the old broken dacron in the middle.
To prevent future damage I'd put a vinyl cap or better a standoff fitting at the end of the spine. Using the standoff fitting be prepared to cut off some millimeters of the spine due to the size of the fitting.
When sewing be careful to clear the trailing edge where the leech line is.
Don't worry about sewing, do some practice on spare parts, if you don't have experience, and then go with confidence