Islands of bone within the soft tissues over the hip | |
Bone spurs from the pelvis or proximal end of the femur, leaving at least one centimeter between opposing bone surfaces. | |
Bone spurs from the pelvis or proximal end of the femur, reducing | |
the space between opposing bone surfaces to less than one centimeter. | |
Apparent bone ankylosis of the hip |
Absence of HO or islands measuring <1 cm in length | |
Islands >1 cm or spurs leaving at least 1 cm between femur and pelvis | |
Spurs leaving <1 cm between opposing surfaces or bony ankylosis |
Heterotopic ossifications strictly below tip of greater trochanter | |
Heterotopic ossifications below and above tip of greater trochanter | |
Heterotopic ossifications strictly above tip of greater trochanter | |
Single or multiple heterotopic ossifications < 10 mm in maximal extent without contact with pelvis or femur | |
Heterotopic ossifications > 10 mm without contact with pelvis but with possible contact with femur; no bridging from femur to proximal part of greater trochanter, with no evidence of ankylosis | |
Ankylosis by means of firm bridging from femur to pelvis |