u/orvinho

Hi everyone,

For about two years now, I’ve been dealing with intermittent pain, sensations of instability, and chronic clicking in my left knee. While it has never completely stopped me from walking, it’s still quite a nuisance in my daily life because I’m very active and workout a lot.

This issue didn't start after a recent trauma or ACL surgery, but I did have some impact injuries on this knee in the past (skateboarding, falls with swelling/edema). My knee occasionally becomes painful during flexion, specifically on the inner side, just above the VMO insertion.

The feeling of instability is there almost every day. As soon as I put a bit of flexion on it, the knee clicks—sometimes loudly, sometimes not—and I can actually feel it shifting. After a period of immobility, I feel a tightness when I start walking again, which disappears after a few steps once my knee clicks and seems to "reset" properly. This unstable feeling subsides during my leg days, likely because they help fire up my quadriceps, and the improvement usually lasts for a day or two after the workout.

Activities that trigger the instability:

• The rowing machine: really worsens that uncomfortable feeling of instability.
• Going up/down stairs and step-ups (Poliquin, Peterson...): very difficult without a thorough warm-up.
• Leg extensions with zero weight (bodyweight only): I get instability and a loud click/clunk at terminal extension. It's a very unpleasant movement, and my knee just feels weak. Curiously, if I use the leg extension machine at the gym, I can load it heavy and get great quad/VMO activation and contraction with no clicking at all.
• Running: causes absolutely no issues (I assume because there's very little knee flexion involved).

While doing some research, I came across Quad AMI (Arthrogenic Muscle Inhibition). I’ve noticed a real struggle to voluntarily contract my left quad, especially the VMO. My right quad is more muscular, which could just be because I'm right-handed, but what really concerns me is the difference in muscle recruitment. When I voluntarily flex my right quad, my VMO gets rock hard, whereas the left one stays relatively soft/mushy.

I brought this up with a physical therapist and a sports medicine doctor, but they didn’t seem too concerned, probably because I’m still fully functional. However, I’m worried that if this is indeed AMI and I keep working out through it, I might cause irreversible damage due to the lack of proper patellar tracking from the VMO.

What do you guys think? Does this sound like AMI to you, or could it be something else (patellofemoral pain syndrome, meniscus tear...)?

I'm pretty stressed about this, so thanks a lot in advance for your insights!