The Saracens skipper is expected to be sidelined for three weeks by the quadriceps injury, meaning he will miss their first two matches of the new Premiership season.
Borthwick will sit out the opener against London Irish, which takes place at Twickenham as part of the traditional London double header on 4 September, and the visit of Sale the following weekend.
That spell in the treatment room will not help Borthwick fight his way back into the England set-up for the autumn internationals.
The 30-year-old lock forward was surprisingly omitted when England manager Martin Johnson named his 32-man elite performance squad last month. That was despite captaining the team for the first 20 Tests of Johnson’s tenure.
Injury ruled him out of the summer tour Down Under, where Lewis Moody impressed as skipper, while locks Tom Palmer, Dave Attwood and Courtney Lawes also advanced their claims.