He was needed because Kevin Lowe wobbled off with knee trouble.
Zimmer has been hobbled for almost two years by knee trouble.
Zendon Hamilton, who was slowed early in the year with knee trouble, is regaining his form.
Quite often, with knee trouble, trigger points elsewhere are responsible but attributed to the knee itself.
He became that, but he played his last four seasons with knee trouble and quit just before the 1954 season.
In 1988 he was hit by severe knee trouble and had to end his professional career.
Healthy again after last season's knee troubles, Drexler is one of the game's most multidimensional talents.
I've had a bit of knee trouble recently but some acupuncture seems to have sorted that out.
Why are women so prone to knee trouble?
It's knee trouble, we're told, that is going to end the 27-year-old's career sooner rather than later.