4 months post acl reconstruction, started slow running, now have tibial plateau pain?

Go slow: Lots of possible causes of tibial plateau including painful hardware, stress fx, inflammation, meniscus tear, arthritis.....I would suggest going slow.

1st, establish Dx: Pain near the joint line has many potential causes. Discuss with your surgeon whether this is medial or lateral and whether you had meniscal or articular cartilage damage. The problem may be as simple as overtraining, but you need a diagnosis before you can direct treatment to resolve your problem.