The A-Host and B-Host differentiation: In the Cierny/Mader classification system for adult osteomyelitis, the host status was added to the anatomic type of infection to articulate the biology of the disease to its treatment (see illustration) This likens our conceptualization of infection to that of the oncologist treating musculoskeletal tumors: treatment and therapeutic outcomes are scaled to grade (biologic activity): A-hosts /low grade tumors need conservative margins and have high success rates; B-hosts /high grade cancers call for radical/wide margins and have lower success rates despite more aggressive treatment. The difference between the two disease states (tumor vs infection) is that the genetic makeup of the tumor cell, itself, determines tumor grade (low vs high) whereas, in chronic osteomyelitis, it is the capacity of the host immune and defense systems (grade of response) that determines outcomes. Yes, there are deadly, resistant and docile bacteria but, even here, treatment and outcomes will, again, be determined more or less determined by the capacity of the host (A vs B).
The biologic grade of the disease can be used to: 1) guide patient selection(table 1; page 4); 2) scrutinize treatment options (article); 3) bring objectivity to with holding treatment either because the patient can function safely with their disease or because treatment, if undertaken, will cause more danger/stress to the patient than no treatment, at all. In the staging system, this later scenario defines the C-Host. A healthy or compromised patient can opt out of treatment to be classified a C-host but revert to an A-host or a B-host status when and if they later become a surgical candidate.
The Clinical Staging system is about the disease, not the healthcare provider, the type of implant, the pathogen or the antibiotic. Yes, there are bad implants, toxic drugs /bugs and inexperienced surgeons ………..but, these, too, are circumstances for which the Staging System was designed to differentiate rather than categorize. In this context, providers, pathogens and post-surgical risks are numerators, not denominators.
Comment: if you now look at our recent outcomes, the discrepancies between A- and B-hosts are shrinking with each year that passes. Why? Because we no longer offer these two cohorts the same treatment —- instead, each treatment is individualized —- options are matched to the physiologic capacity of the host.
I agree there are degrees of compromise just as there are differences in the sweetness of grapes. But, over the years, I have stopped trying to sort “bad” factors from the “not so bad”. To me, anything less than normal is a compromise worthy of an effort to counter or negate its affect(s) on wound healing ———– I know that a reversed compromise will improve outcomes (somewhere, sometime). GC 11/19/09