The 35-year-old, who will undergo an examination of the problem on Tuesday, was unable to complete his 11th over for Hampshire against Nottinghamshire on Day 2 at Southampton and was forced to leave the field.
Steyn has had a horrible run of injuries over the last two years, hampering his bid to become South Africa's record test wicket-taker, though he did equal the record in Sri Lanka last month where he picked up only two wickets in the two-match series.
Both Steyn and Shaun Pollock have each taken 421 test wickets.
A serious shoulder injury in Australia in November 2016 kept him out for most of last year before a heel problem sustained in his comeback Test against India in February sidelined him once more.
First Published: August 21, 2018, 3:03 PM IST