Knee osteoarthritis is one of the most common reasons people walk into our sports chiropractic office in Murray, and it is also one of the most misunderstood. Most patients arrive believing their knee is simply “worn out” and that nothing can be done but wait for a replacement. The reality is more hopeful and more interesting. To make good decisions about your knee, it helps to understand what the joint is made of and what is actually happening inside it when osteoarthritis develops. That is the goal of this first article in our four-part series.
A Quick Tour of the Knee Joint - Involved Anatomy
The knee is where three bones meet: the femur (thigh bone), the tibia (shin bone), and the patella (kneecap). Where these bones meet, their ends are capped with articular cartilage, a smooth, slippery, rubbery tissue that is only a few millimeters thick. Healthy cartilage is remarkably low-friction, allowing the bones to glide across one another thousands of times a day without any pain or grinding.
Between the femur and tibia sit two C-shaped shock absorbers called the menisci. They spread load across the joint, add stability, and protect the cartilage underneath. Surrounding the whole joint is a capsule lined with synovium, a thin membrane that produces synovial fluid to lubricate and nourish the cartilage. Ligaments such as the ACL, PCL, LCL, and MCL hold the bones in alignment, while the muscles that cross the knee, especially the quadriceps and hamstrings, control movement and absorb force. Just beneath the cartilage lies the subchondral bone, which plays a bigger role in osteoarthritis than most people realize.
So, What is Osteoarthritis, Really?
For decades, osteoarthritis was described as “wear and tear” of the knee joint, as if the joint were a tire slowly balding. Current research paints a very different picture. OA is now understood as an active disease of the entire joint, not just passive erosion of cartilage. Cartilage, subchondral bone, the synovium, ligaments, and even the surrounding muscles are all involved in the process. 1
In a healthy joint, cartilage is constantly maintained by cells called chondrocytes, which balance the breakdown and rebuilding of the cartilage matrix. In osteoarthritis, that balance tips toward breakdown. Chondrocytes shift into a more inflammatory, catabolic state, releasing enzymes that degrade the cartilage faster than it can be repaired. Low-grade inflammation in the joint lining adds to the problem, and the subchondral bone begins to remodel and stiffen, sometimes forming the bony spurs (osteophytes) seen on X-rays. 1 2
Why the Joint can Hurt, and Why it Sometimes Doesn’t.
Here is a detail that surprises many patients: cartilage itself has no nerve endings and no blood supply. That means early cartilage changes can be completely painless. Pain in osteoarthritis usually arises from other structures, such as the richly innervated subchondral bone, the inflamed synovium, the stretched joint capsule, and the irritated surrounding tissues. 2, 3 This is one reason the amount of change on an X-ray often does not match the amount of pain a person feels. Some people with dramatic imaging have little pain, while others with mild imaging changes experience considerable pain.
What Drives the Knee Osteoarthritic Process Forward?
Osteoarthritis is best understood as an imbalance between the load placed on a joint and that joint’s ability to handle it. Mechanical stress is a key driver: repetitive overload, previous injury, joint malalignment, or weak supporting muscles can all push the joint past what it can comfortably tolerate, triggering the cellular and inflammatory changes described above. 1 Once the cycle starts, pain leads to less movement, less movement leads to weaker muscles and stiffer tissue, and a more poorly supported joint is loaded even less evenly, which can accelerate the degenerative process.
That cycle is exactly why the modern, evidence-based approach to knee OA emphasizes restoring the joint’s capacity through movement, strengthening, and load management rather than simply resting and waiting. International treatment guidelines now list exercise and appropriate physical care as core, first-line strategies for knee osteoarthritis. 4
Key Takeaways Before we Progress to Part 2
Knee osteoarthritis is a whole-joint condition driven by a mismatch between load and capacity, not an inevitable, untreatable breakdown. Because the joint is a living, adaptable system, the way you load it, strengthen it, and care for it genuinely matters. In Part 2, we’ll look at the specific factors that raise your risk, what you can do to help prevent osteoarthritis or slow its progression, the role nutrition plays, and the warning signs that mean it’s time to have your knee evaluated.
✓ The knee is a load-bearing joint where the femur, tibia, and patella glide on a thin layer of articular cartilage cushioned by menisci.
✓ Osteoarthritis (OA) is not simply “wear and tear”; it is an active, whole-joint disease involving cartilage, bone, and the joint lining. 1
✓ Cartilage has no blood supply or nerves, so early OA is often silent until changes reach the bone and surrounding tissues. 2
✓ Understanding the mechanism helps explain why movement, load management, and targeted therapy, not just rest, are central to care. 4
Not sure whether your knee pain is early osteoarthritis or something else? A focused evaluation is the best place to start. Our sports chiropractic team assesses how your knee moves and loads, then builds a plan around your goals, no guesswork, no assuming surgery is inevitable.
Frequently Asked Questions
Is knee osteoarthritis just wear and tear?
No. While mechanical load matters, osteoarthritis is an active disease of the whole joint involving cartilage cells, low-grade inflammation, and changes in the underlying bone, not simply passive erosion. This is why targeted movement and therapy can meaningfully influence how the joint feels and functions. 1
Why does my knee X-ray look bad but not hurt much (or vice versa)?
Cartilage has no nerves, so cartilage loss alone is painless. Pain comes from the bone beneath the cartilage, the joint lining, and surrounding soft tissues, which is why imaging severity and pain levels often don’t match. 2 3
Is there anything that can be done for knee osteoarthritis besides surgery?
Yes. For most people, surgery is not the first step. Evidence-based guidelines recommend exercise, load management, and conservative care such as joint manipulation, dry needling, and shockwave therapy as first-line treatment, and many patients manage their knees well for years without an operation. 4
What structures make up the knee joint?
The knee is formed by the femur, tibia, and patella, capped with articular cartilage and cushioned by two menisci. A synovial lining lubricates the joint, ligaments provide stability, and the quadriceps and hamstrings control and absorb load.
REFERNECES
1. Tong L, et al. Current understanding of osteoarthritis pathogenesis and relevant new approaches. Bone Research. 2022;10:60. https://www.nature.com/articles/s41413-022-00226-9
2. Du X, et al. Research Progress on the Pathogenesis of Knee Osteoarthritis. Orthopaedic Surgery. 2023. https://onlinelibrary.wiley.com/doi/10.1111/os.13809
3. Yao Q, et al. Osteoarthritis: pathogenic signaling pathways and therapeutic targets. Signal Transduction and Targeted Therapy. 2023;8:56. https://www.nature.com/articles/s41392-023-01330-w
4. Bannuru RR, et al. OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis and Cartilage. 2019;27(11):1578-1589. https://pubmed.ncbi.nlm.nih.gov/31278997/