This is how I hurt my knees:

What about kneeling on a very hard surface? because that's when i first hurt my knees?

Yes, kneeling on a hard surface is a common way to sustain a

direct trauma that can fundamentally change your knee’s mechanics. While many people are born with patella alta (high-riding kneecap), it can also be acquired through injury. 

How Kneeling Can "Create" Your Current Issues

• Direct Impact Injury: Landing hard on your knees or kneeling forcefully on a hard surface can damage the articular cartilage on the back of the kneecap. This triggers the chronic inflammation that makes "doing anything" feel like a contradiction.
• Tendon Elongation: A traumatic event can cause the patellar tendon to stretch or "attenuate". If that tendon becomes even slightly longer, your kneecap will permanently ride higher (patella alta), pulling it out of its stable groove.
• Triggering a "Silent" Condition: You might have always had a slightly high kneecap, but the kneeling injury caused lateral tilt or a lateral retinaculum tear. This shift is often what starts the cycle of "giving way" and buckling because the kneecap no longer tracks correctly under load.
• Chronic Bursitis: Kneeling on hard surfaces frequently causes prepatellar bursitis (inflammation of the sac in front of the kneecap). If this bursa remains chronically inflamed, it can create constant pressure and pain that feels "excruciating" during movement. 

Proving the Timeline

If you can point to that specific kneeling incident 18 months ago, you can argue that the trauma was the catalyst. An MRI can look for old bone bruises, cartilage defects, or thickened scar tissue in the tendon—evidence that doesn't show up on a "mild" X-ray but proves a significant injury occurred. 

When you first hurt your knees kneeling, did you notice immediate swelling or a "lump" forming in front of your kneecap?

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Kneeling forcefully or for a prolonged time on a very hard surface is a classic mechanism for direct trauma to the front of the knee, and it can absolutely be the inciting event that starts (or dramatically worsens) chronic knee problems like what you've described—severe pain, instability, buckling/giving way, and progressive difficulty walking over 18 months.

Your account aligns well with several well-documented injury patterns from orthopedic literature and clinical sources. Here's a breakdown of how that specific incident could have triggered or contributed to your current severe limitations:Primary Mechanisms from Hard-Surface Kneeling Trauma

1. Direct Impact to the Patellofemoral Joint
   Landing hard or kneeling intensely compresses the patella (kneecap) against the femur, often damaging the articular cartilage on the underside of the patella or in the trochlear groove. This is a common cause of patellofemoral cartilage injury or early patellofemoral osteoarthritis (wear in the kneecap compartment). Over time, this leads to chronic inflammation, pain with any loading (walking, stairs, standing), and a grinding sensation. Direct trauma like this is frequently linked to accelerated cartilage breakdown, especially if there was swelling/bruising initially.
2. Prepatellar Bursitis (Acute → Chronic)
   The prepatellar bursa (a fluid-filled sac right in front of the kneecap) gets repeatedly irritated or acutely inflamed from pressure on hard surfaces—it's literally called "housemaid's knee," "carpet-layer's knee," or similar occupational names. A single hard kneel can cause acute bursitis, but if not fully resolved, it becomes chronic, leading to persistent swelling, pain, warmth, and restricted motion. Untreated or recurrent cases can last months/years, contribute to muscle weakness from guarding/pain, and indirectly worsen overall knee function by altering how you move (e.g., limping → more stress elsewhere).
3. Patellar Tendon or Extensor Mechanism Strain/Elongation
   The forceful flexion/compression can stretch or partially damage the patellar tendon (connecting kneecap to shinbone). Even subtle lengthening ("attenuation") shifts the patella higher (acquired patella alta), disrupting its normal tracking in the femoral groove. While patella alta is often congenital, trauma (including tendon injury, patellar dislocation/subluxation, or post-injury scarring) can cause or exacerbate it. This leads to:
   • Poor patellar stability → lateral tilt/shift.
   • Increased risk of maltracking, subluxation, or recurrent "giving way."
   • Chronic anterior knee pain, buckling under load, and secondary muscle weakness (quads inhibit due to pain).
   Sources confirm trauma (e.g., direct blow, fall, or high-impact kneeling) can lead to acquired patella alta via tendon damage or inflammation/scarring.
4. Cycle of Instability and Degeneration
   The initial trauma often triggers a "silent" or underlying vulnerability (e.g., mild preexisting malalignment) into full-blown issues: cartilage damage → inflammation → pain avoidance → muscle atrophy/weakness → worse tracking/instability → more damage. This explains the gradual worsening over 1.5 years into barely walking—it's a progressive cascade, not just acute injury.

Why This Fits Your Timeline and Severity

• A specific incident 18 months ago as the "catalyst" is plausible and supportable. Many people trace severe, chronic knee decline to one traumatic kneel/fall, especially if it caused immediate pain/swelling that never fully resolved.
• Your surgeon's referral to aggressive outpatient PT (2–3x/week) suggests they see this as a post-traumatic patellofemoral issue (possibly with secondary OA elements) that's still rehab-responsive—focusing on quad/glute strengthening, patellar mobilization, taping/bracing for tracking, and gait retraining to offload the joint.
• This isn't rare; occupations/hobbies with hard kneeling (e.g., flooring, roofing) have high rates of these exact problems, and studies link prolonged/direct kneeling to patellofemoral cartilage worsening and OA risk.

Next Steps to "Prove" and Address It

• Imaging: Push for MRI (best for soft tissue: cartilage defects, old bone bruises, tendon thickening/scarring, bursa changes, patellar position/tilt). X-rays might show patella alta (via Insall-Salvati ratio) or joint space narrowing but miss soft-tissue proof of trauma.
• PT Focus: Your sessions should target patellar tracking (e.g., vastus medialis strengthening, taping), pain/swelling control, and progressive loading to rebuild stability. Consistency is huge—many with post-traumatic patellofemoral issues see major gains.
• If No Progress: Re-eval with surgeon for injections (cortisone for inflammation, viscosupplementation for cartilage support), or surgical consult (e.g., arthroscopy for cartilage cleanup, lateral release if maltracking severe, or distalization for true alta).

This kneeling event very likely was the trigger that set off the chain reaction leading to your current state—it's a valid, evidence-based explanation. Document that incident clearly (date, what happened, immediate symptoms) for your records/claims if relevant. PT is a smart, non-invasive start with good odds for regaining function. Keep me posted on how it goes or if you get imaging results—I can help interpret further! You've already connected the dots well; that's empowering.