Knee Pain: Symptoms, Causes, and Treatments

Problems in the Knee

The knee doesn’t have much protection from trauma or stress (pressure or force). In addition to wear and tear on the knee, sports injuries are the source of many knee problems.


Knee symptoms come in many varieties. Pain can be dull, sharp, constant or off-and-on. Pain can also be mild to agonizing. The range of motion in the knee can be too much or too little. You may hear grinding or popping, the muscles may feel weak or the knee can lock. Some knee problems only need rest and ice, others need physical therapy (knee rehab exercises) or even surgery.

  • Swelling: One of the most common symptoms is local swelling. There are two types of swelling. One is caused by the knee producing too much synovial fluid and the other is caused by bleeding into the joint (hemarthrosis). Swelling within the first hour of an injury is usually from bleeding. Swelling from 2-24 hours is more likely to be from the joint producing large amounts of synovial fluid trying to lubricate an abnormality inside the knee.  The best home treatment for swelling is R.I.C.E. therapy. Chronic swelling can distend the knee, prohibit full range of motion and the muscles can atrophy from non-use. Also, if the cause of the swelling is blood, the blood can be destructive to the joint.
  • Locking. Locking is when something keeps the knee from fully straightening out. This is usually a loose body in the knee. The loose body can be as small as a grain of sand or as big as a quarter. The best treatment is removal of the loose body by arthroscopy. Another type of locking is when the knee hurts so bad that you just won’t use it. The best treatment here is rest and maybe some ice; swelling is not usually present.
  • Giving Way. If your kneecap slips out of is groove for an instant, it causes your thigh muscles to loose control causing the feeling of instability—that is, you don’t feel  your knee is stable and won’t support your weight—so try to grab hold of something for support. Giving way can also be caused by weak leg muscles or an old ligament injury.
  • Snaps, Crackles and Pops. Noises coming from  your knee without pain are likely nothing to worry about. Sometimes the noise is caused by loose bodies that just float around and are not causing pain or injury to the knee. However, If you have pain, swelling or loss of knee function, you should see an orthopedist. The most common cause—chondromalacia patella—is caused by an injury. Another common cause is a dislocating kneecap—that is, a kneecap that keeps slipping out of its groove. Pops without trauma (injury) are not worrisome, pops with trauma can mean ligament tears. Crackling, grinding or grating (crepitus) means there is a roughness to the bone surfaces and likely from degenerative disease or wear-and-tear arthritis (osteoarthritis).
  • Pain and Tenderness. Where and how bad the pain is will help find the underlying cause. It also helps to know what caused it and what makes it hurt. Pain that gets worse with activity is often tendinitis or stress fractures. Pain and tenderness accompanied by swelling can be more serious such as a tear or sprain. Some pain can be caused by muscles spasms associated with trauma.

Lateral view of knee tendons, ligaments and bones.

Pathological Conditions and Syndromes in the Knee

  • Osteochondritis Dissecans
  • Osteoarthritis (Degenerative Arthritis) – Caused by aging and wear and tear of cartilage, symptoms may include knee pain, stiffness, and swelling.
  • Infectious Arthritis
  • Chondromalacia Patellae – Pain from irritation of the cartilage on the underside of the kneecap; a common cause of knee pain in young people.
  • Gout – A form of arthritis caused by buildup of uric acid crystals in a joint. Sometimes the knees may be affected causing severe pain and swelling.
  • Plica Syndrome
  • Rheumatoid Arthritis – An autoimmune condition that can cause arthritis in any joint, including the knees. If untreated, rheumatoid arthritis can cause permanent joint damage.
  • chondromalacia
  • osteoarthritis

Traumatic Knee Injuries

Repetitive Knee Injuries

  • Patellofemoral Syndrome (Runner’s Knee)
  • Tendonitis
  • Bursitis (Housemaid’s Knee)
  • Illiotibial Band Syndrome
  • Osgood-Schlatter Disease

Types of Knee Surgery

Knee replacement surgery

Physical Therapy

Physical therapy is often a helpful way to review some knee problems, in place of surgery. Your doctor will give the best protocol for your specific situation. After you have found relief perhaps a career in Physical Therapy would be a good thing for you to help others in their pain.


  1. Andrea Myers says

    It really helped me when you said that pain that gets worse with activity is often tendinitis or stress fractures. My brother usually participates in running events, and he informed me yesterday that he’s experiencing knee pain after he runs. I’ll advise him that he should consider visiting an orthopedist for consultation.

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