Meaning of the Sanskrit Word: janubhyam

  janubhyam—with its two knees    SB 8.11.15
  janubhyam—by the strength of Their knees    SB 10.8.21
  janubhyam—on the ankles    SB 2.5.40, SB 2.5.41, SB 2.5.40-41

Can't find any compound Sanskrit words containing janubhyam.