The number of cusps involved by HO The number of AVs
Total classified AVs with HO (n=20) 1 cusp only 9
  ≥2 cusps 11
Classified tricuspid AVs with HO (n=14) 1 cusp only 6
  2 cusps 6
  All 3 cusps 2
Classified bicuspid AVs with HO (n=6) 1 cusp only 3
  All 2 cusps 3
AV: aortic valve; HO: heterotopic ossification
Table 3: The number of cusps involved by heterotopic ossification in each case on 20 classified aortic valves.