Charles Ellicott Commentary Deuteronomy 28:35

"Jehovah will smite thee in the knees, and in the legs, with a sore boil, whereof thou canst not be healed, from the sole of thy foot unto the crown of thy head." — Deuteronomy 28:35 (ASV)

A sore botch. — A boil, as in Deuteronomy 28:27.

In the knees. — Compare Ezekiel 7:17; Ezekiel 21:7, All knees shall be weak as water.