Yeah such a shame. The boundary edge was to blame as it was sand not grass and he tries to slide but his foot got caught in the sand and he went right over it. Horrible to watch live.
Seen an interview with him a few years ago and he admitted he knew his career was effectively over after that but he put his body through absolutely everything for 18 months to try to get fit for The 2005 Ashes. And he did and bowled brilliantly in that series until Edgbaston and he knew then it was over after that injury