I don’t have any experience in the area of joint replacement. The possible effect of P trait is interesting, but I have no hypothesis on the possible mechanisms involved.
Having worked over twenty years in a cardiac ICU, I did have the impression that risk factors for coronary artery disease (CAD) were A trait and A− trait. The type having the lowest predisposition to CAD was the NP type (indeed an NP type with CAD was a rare bird). However, N and NP types were common among our patients having mitral and aortic valve replacement, especially those with rheumatic valve disease.
Regarding the ABO types, we have commented previously that in contradistinction to NPA types, ABO type is determined by a single gene, presumably distinct from the NPA loci. If one speculates that the ABO gene is in the “third tier” of personality determination (after female-female gender and the NPA traits), perhaps with a strong effect on temperament, then that would be an extraordinary hypothesis. But, as the saying goes, “extraordinary hypotheses require extraordinary evidence”.