Repair macbook hard disk

A late 2007 Macbook refuses to boot.

Holding down Command-S brings up single user mode.

Running fsck -fy doesn't fix it, but yields the error "The volume Macintosh HD could not be repaired".

Running fsck -d to get debug info gives more detail:

• root device is /dev/rdisk0s2
• journal replayed successfully or journal was empty
• Index key doesn't match first node key
• Invalid index key (4, 35529)
• rebuilding catalog b-tree
• hfs_UNswap_BTNode: invalid node height (1)
• volume type is pure HFS+

On a parallel track, trying to create a bootable USB stick to use linux tools to troubleshoot the corrupt root filesystem.