Don't think I can help you out with what it is....but I think I can help you with what it's not. ACL injuries usually require an abnormal motion of the knee, such as plant foot, rotate hips, and sit. Typically it will swell and not necessarily hurt. This is speaking from experience. So unless you've had a funny fall from skiing, basketball, etc, prior to your run, I don't think you have ACL damage.

However, there are plenty of other things that can go wrong with a knee. If conditions don't improve by the end of the week. Seeing a doc probably isn't a bad idea.

Hey

I would probably go and see a doc or physio to make sure, in the mean time ice and rest are probably a good idea. I may be tension in your quads as one of them attaches on the inside of the knee, maybe tension in the tendon there? Stretching quads (and hamstrings - part of these attach there too) may help but if you do stretch it just do it lightly as if the muscle is strained it may not help. Sorry if this is a bit rambling!!

I had a similar pain in my knee about three months ago when I started some higher mileage training than I was use to (35 miles a week/13-16 miles on my long run). The doctor said that the pain and discomfort was the result of putting too much mileage on my knees to fast.

So I shortened my long runs and scaled back the mileage. Pain went away and three months later the knees can handle the 35 miles a week with no pain.

This might be what you are experiencing, but I would see a doctor and have the knees looked at.

I've had something like that before.... it could be where you patella (kneecap) rubs against your femur (theigh bone) when you bend your knee or apply pressure to the kneecap.... patellofemoral pain feels like what your describing... (although knees are so complicated that the treatment for the same symptom may need to be radically different between people) I had to take a week or two off completely (except swimming) and ice it and stretch my quads, hampstrings, and itb's religiously...

IT Band stretches might releave some of the tension on the inside of your knee. Ask a trainer for the best stretches to target your IT band.

I had exactly the same problem when I trained for a marathon last summer. It appeared to me to be a problem in my knee but after asking around ( I train with a lot of doctors ), I found that the problem was actually starting up in my quad. You may want to consider getting a good massage in the near future and then from that point on make sure you warm up really well ( that includes stretching ). After I did that I began to have fewer and fewer problems. If the pain is in the inside of your right knee, you'll probably find that if you put pressure on the outside of your quad it will be very tendor. That's what I found with my issue and hopefully yours will be the same because it's really not that tough to get over. Good luck with the Marathon training and remember you play it smart.

TriQuest- I was a physician assistant, emergency medicine, in a former life. Let me humbly offer my 2 cents...
1. DO NOT MIX IBUPROFEN AND CELEBREX!!! You risk serious stomach and kidney problems. For my money, ibuprofen, taken with food and in appropriate doses, in someone with no history of asthma, high blood pressure, diabetes or stomach problems, (ulcer, reflux, frequent indigestion etc) is perfectly adequate.
2. Ice is severly under-rated. Ice is great! Use it.
3. It is tough to tell exactly what the problem is without a proper physical exam. Even then, it sometimes requires an MRI... so go see a doc that specializes in sports med, especially running. They aren't hard to find. Having said that, my first thought was maybe a pes anserine bursitis. Treatment is Motrin, ice and so on... BUT GO SEE A DOCTOR. Don't let this turn into something nasty that will take along time to heal.
4. Comon-sense rules apply to injuries like this- if it hurts, don't do it.

Hope that helps... let me know if I can be of any further assistance.

Hi, My two cents for what it is worth. Having torn my ACL in the past, I knew it right away. I was changing directions while playing soccer and have memories of writhing in pain on the ground. It is also accompanied by marked swelling and often instability in the knee joint. Your description of pain with loading the knee while in a flexed(bent) position, sounds like chondromalacia also called patellofemoral syndrome as mention earlier in the thread. Sometimes you may actually feel the grinding when you are loading it. I suffered from this too. I believe that mine was caused by running up too many inclines as well as running on severely crowned roads. It is basically caused by the Femur being driven into the back of the patella when the knee is not in extension. If this is the problem, you can help it by doing leg extensions on a weight machine to strengthen the medial head of your Quadriceps muscle. When you do the extension you only need to do the last 45 degrees and should point your toes out. This will work the VMO (medial portion). You can set this pretty easily on any machine. Each leg should be worked by itself. You can google chondomalacia and/or go to sites like Runners World. I believe they talk about it more. If it seems to be swelling and hurting with weight bearing it may be a meniscal problem. Good Luck