Tepid growth among the nation’s 350 largest law firms in 2012 showed that the highly leveraged, bottom-heavy ways of doing business have become unsustainable.

Overall, the nation’s largest 350 law firms grew by just 1.1 percent last year. Partner ranks expanded by 1.5 percent, while associate numbers edged up by just 1.0 percent. The number of other lawyers, including staff and counsel positions, dropped by 0.2 percent in 2012.