Shatkriyakala – 6 stages through which doshas travel and create a disease – the changes that occur in doshas that create disease. To create disease, change in doshas + kha vaygunya (weakness in body) must both be present for disease to take place. Ex. Some joint impact, say a fall or injury, then later in winter maybe knee starts to ache. Because the patient hasn’t healed area fully, so as doshas increase, then the vitiated doshas attack that particular point later. Western medicine calls it arthritis. Even knee replacement or surgery touches the organ and therefore will later have problems with the knees. In some cases, orthopedic surgery can be very helpful – breaking off the head of the femur for example. But of course then you have to do things to reinforce. In case of old people, without the surgery they may not be able to walk and therefore couldn’t do those ayurvedic things to improve bone density. So better to do the surgery than not in this case. Looking at the patient, we can understand bones need strength – is it something we can give through nutrition or lifestyle, is it due to aama or an obstruction?, these are issues to understand for treatment. Some mechanical exercises can help to train the bones in a specific manner to help.

So when a particular impact or disease has happened to a specific organ, either internal or external, congenital, etc. if remains untreated, that particular organ remains weak. Then next time anything happens, vitiation occurs, that is the organ that becomes affected. The treatment isn’t finished just because the symptoms are gone. We need to help the organ to regain its strength – that is rasayana treatment. Treatment should always be in such a manner that there shouldn’t be any weakness in body – even srotas should be in order. Srotovaygunya/Kha-vaygunya – weak srotas.

Being weak doesn’t mean disease – only weakness doesn’t create disease, but if doshas are aggravated – say eating a lot of vata aahara and doing a lot of vata vihara activities, will aggravate the weak spot. If doshas are increasing, will show some signs of vata prakop, but that won’t be considered a disease. Some kind of stiffness in body due to vata prakopa, but if agni is strong enough and we’re back on regimen, will come back into balance. Only doshas or only weak spot are not sufficient to generate disease, only the both together are sufficient to create disease.

There are ways that we weaken our srotas – taking naps every day can weaken medavaha srotas. If you eat heavy meals and stay away from exercise and drink alcohol, all that excess kapha will get stuck in the medavaha srotas. So classic siesta lifestyle is guaranteed to weaken the medavaha srotas. The aahara rasa will always be heavy and bulky beginning at gross digestion, and then kapha will be qualitatively and quantitatively increased/vruddhi.

If you have injury or weakness it is possible to heal so that will not cause weakness in future. So with knee injury, oleation with medicated oils, then specific herbs – bala, mahanarayan externally, then eat internally bala, mahanarayana. Ex. Amashaya if sthanavaygunya – must replenish with lots of aap mahabhuta. Remove weakness as a prevention for disease. Weakness can occur when vruddhi is present as well as with a kshaya/depletion. Ex. Rasa dhatu increased- why? Is it because rasa agni is low, work on increasing that agni so that it can maintain proper balance. Sometimes herbs will help to heal individual dhatu agni. (shunthi for overall agni)

Article source: http://trueayurveda.wordpress.com/2014/08/29/shatkriyakala-6-stages-of-disease-formation/