Heterotopic Ossification in Vertebral Interlaminar/Interspinous Instrumentation: Report of a Case

Table 1

McAfee’s classification of heterotopic ossification (HO).

McAfee’s classification
(0) No HO
(I) Islands of bone not within the margins of the disc and not interfering with motion
(II) Bone within the margins of the disc but not blocking motion
(III) Bone within the margins of the disc and interfering with motion of the prosthesis
(IV) Bony ankylosis

^*Adapted from McAfee et al. [39].