Alonzo Mourning has decided to retire rather than mount another NBA comeback at age 38. The seven-time All-Star center said Thursday he won't return from a devastating leg injury in 2007. He's not under contract but had been working out at the Miami Heat's complex and still had a spot in the team's locker room. Mourning hasn't played since tearing the patella tendon and quadriceps muscle in his right leg on Dec.