An adjustable support assembly for an orthopedic brace has a support bar, a housing and a locking mechanism. The housing includes a travel track which receives the support bar. The locking mechanism includes a lock stop and a lock peg array having at least one column and a plurality of rows. The lock stop is perpendicularly positioned between two lock pegs in adjacent rows to prevent displacement of the support bar in the travel track when the length locking mechanism is in the closed position and the lock stop is parallely positioned to enable displacement of the support bar in the travel track when the length locking mechanism is in the open position.