Why Does My Knee Hurt?

Knee pain, unfortunately, is common among people of all ages. Various conditions or injuries can cause the pain, and each is treated differently. Following are some of the reasons why your knee may hurt.

Arthritis – three common types

Osteoarthritis, the most common type of arthritis, is a “wear-and-tear” condition that occurs when the hard, slippery tissue that covers the ends of the bones wears away. In a non-arthritic knee, this tissue – called cartilage – acts as cushioning. Without the cartilage, the bones of the joints rub more closely together, resulting in pain, swelling and stiffness.  While osteoarthritis can occur in young people, it is more common after age 45, and women develop osteoarthritis more often than men. The knee is one of the most affected joints. 

With post-traumatic arthritis, the wear and tear of a joint is accelerated by a physical injury resulting from sports, a car accident, fall or other physical trauma. Symptoms include joint pain, swelling and stiffness.

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Inflammatory arthritis, which is usually caused by a malfunctioning immune system, causes pain and stiffness, particularly in the morning or after periods of inactivity. The morning stiffness typically lasts more than an hour. 


Treating arthritis

One step you can take to ease the symptoms of arthritic knees is to lose weight, because every pound of extra weight you carry puts 3 to 4 pounds of extra weight on your knees.  Even
losing a small amount of weight can significantly decrease pain. 

Pain can also be treated with over-the-counter pain relievers and anti-inflammatory medications – but check with your doctor before taking them for longer than 10 days, because extended use of these medications increases the chance of side effects. 

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If further treatment is needed, you may benefit from various types of injections into the knee. Cortisone may be injected to reduce inflammation or hyaluronic acid may be used to lubricate the joints. Two relatively new treatments are injections of stem cells to attempt to regenerate cartilage and speed healing or platelet rich plasma (PRP), which isolates anti-inflammatory characteristics and growth factors from a patient’s own blood in order to utilize the body’s natural ability to heal.

If the pain in your knees becomes severe enough to affect your quality of life and other remedies do not help, you may consider a partial or total knee replacement – depending upon whether the damage from arthritis has affected only one area of the knee or the whole knee. 


Meniscus Tear

Have you ever heard someone say that he “tore his meniscus” and wondered what that was? Each knee has two C-shaped pieces of cartilage called menisci that provide cushioning between the shinbone and thighbone. A forceful twist or rotation of your knee, or even kneeling or deep squatting, sometimes causes the meniscus to tear. The tear leads to pain, swelling and stiffness, and there may be clicking, catching, popping, locking or an inability to extend the knee fully. 

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Risk for acute meniscus tears is high among athletes, especially those who play contact sports, such as football, or sports involving pivoting, such as tennis or basketball. 

Sometimes rest, ice and anti-inflammatory medication will provide enough relief to allow the injury to heal on its own, but often arthroscopic surgery will be necessary. Through a tiny incision, the surgeon inserts an arthroscope, which has a light and a small camera to transmit an image of the inside of your knee onto a monitor. This allows the surgeon to see the tear and perform surgery through the arthroscope, if necessary. If it isn’t possible to repair the torn meniscus, it may be surgically trimmed in a procedure called a partial meniscectomy. After surgery, you will be given exercises to do that will help you regain strength and stability.

When a tear occurs in people with end-stage arthritis, it is called a degenerative tear – one resulting from years of wear on the knees. Degenerative tears are treated in much the same way as arthritis of the knee.


Focal Cartilage Defect

Injury to knee cartilage can develop gradually over time from stress due to improper mechanics or leg alignment (bowed legs or knock knees), or it may occur suddenly from a traumatic injury such as a blow to the knee in an accident. Focal cartilage defect often affects young people who do not have arthritic changes in their knees.  

Typical symptoms of focal cartilage defect are pain and occasional instability. There may be a “catching” if a piece of cartilage has been dislodged and is trapped inside the knee.

Conservative treatment involves activity modifications and anti-inflammatory medication. However, the defects generally don’t heal well because cartilage does not contain vascular, nervous and lymphatic tissue or an active healing mechanism. 

There are a number of surgical options for treating the damaged cartilage:

Arthroscopic Debridement.  Loose pieces of cartilage are removed to prevent their impingement on the joint.

Microfracture. Holes are drilled into the bone to stimulate the body to regrow or repair the damaged area.

Autologous chondrocyte implantation. A biopsy of the patient’s own healthy cartilage is taken and cloned in a laboratory. During a second procedure, millions of the cloned cells are implanted into the defect.

Cartilage replacement. The entire
defect area, including the underlying bone, is replaced with artificial or donor cartilage, or occasionally cartilage that
is transferred from a non-essential area of the patient’s own knee.

Occasionally the above procedures are combined with an osteotomy, which involves the cutting and repositioning of the bone to correct abnormal alignment
or relieve stress on the damaged area.



A bursa is a fluid-filled sac that cushions points between muscles, tendons and bones.  The inflammation of a bursa, called bursitis, can be very painful. Each knee has 11 bursae, but knee bursitis most often occurs over the kneecap or on the inner side of the knee below the joint. Usual treatment is rest, ice, compression and anti-inflammatory medications. It can take several months for bursitis to improve, but it usually resolves on its own and does not require surgery. Occasionally, an injection of cortisone or other anti-inflammatory agents may be given. 



Knee tendons are thick cords that attach the bone to muscles. Athletes who do a lot of running and jumping often develop inflammation and swelling of these tendons due to overuse. Older athletes whose tendons have lost elasticity are at higher risk of developing tendonitis. The most commonly irritated tendons are the patella (on the front of the knee) and quadriceps tendon (above the kneecap).

If you have tendonitis, the R.I.C.E. method of treatment is recommended: Rest the knee, Ice the knee to reduce pain, inflammation and swelling (wrap ice in a towel and limit to 20 minutes at a time), Compression (lightly wrap the knee during icing) and Elevation of the leg.  Activities should be modified until symptoms disappear. Anti-inflammatory medications can be taken. In rare cases, tendonitis persists or keeps recurring. In that case, a cortisone injection or surgery may be needed.


Knee Sprain or Tendon or Ligament Tear

Sometimes a sudden injury resulting from a twist or fall may stretch or even partially tear one of the many ligaments or tendons in the knee. Such sprains and partial tears usually resolve with rest.  In more severe cases where the knee is unstable, it may be necessary to wear a brace. If ligaments or tendons are completely torn, surgery may be needed to repair or replace them.  


Your Back

Nerves in the lower back that are pinched due to lumbar spine arthritis or herniated discs can cause pain in a knee if the pinched nerve is one that travels to the knee. The discomfort is a radiating pain that originates in the back or upper leg.  It takes a keen doctor to diagnose this unusual type of knee pain, because the results of knee X-rays and MRIs are normal. 


Your Hip

There are many nerves traveling across the hip that continue down and across the knee, so hip pain can also be felt in the knee. Whenever you see a doctor for knee pain, he or she should always examine your hips to make sure that they are not stiff or that movement of your hips does not reproduce pain in your knee.


Stress Fracture and Subchondral Insufficiency Fracture

A stress fracture is caused by repetitive impact and is often seen in people training for long-distance running. Pain is present with walking and running but is usually not present when sitting or lying down. A stress fracture is an incomplete break, so it does not generally require surgery. However, there may be a need for a period of non-weight-bearing with crutches and immobilization with a cast or hard boot.

A subchondral insufficiency fracture is often seen in older patients with weakened bones due to osteoporosis or osteopenia (a precursor to osteoporosis) who also have weakened or thinning cartilage from arthritis. Without support from strong cartilage, the weakened bone is more stressed and can partially collapse.  Treatment often consists of periods of non-weight-bearing with either a walker or wheelchair and can be supplemented by medications that encourage or support bone growth and formation.

Because both stress fractures and subchondral insufficiency fractures are incomplete fractures, they usually do not show up on plain X-rays and can only be diagnosed with an MRI. 

Exciting News in Knee Replacement!

The first robotically-assisted total knee replacement in the region was recently performed at Phelps Memorial Hospital by orthopedic surgeon Jason Hochfelder, MD. Until now, this leading-edge technique for patients with advanced knee arthritis was not available anywhere else in New York State north of Manhattan.

The technique, which uses “bone morphing” technology, generates a 3-D display of the patient’s anatomy in real time, enabling the surgeon to precisely position the implant and optimally align the leg. Better alignment can reduce the need for revision surgery, improve joint function and increase the life of the implant.  

Dr. Hochfelder will be giving a presentation on this and other new technology and advances in knee replacement on Tuesday, April 12 and Tuesday, May 10 at 6:00 pm
in the Phelps Auditorium. To attend, call 914-366-3100.

Orthopedic surgeon Jason Hochfelder, MD, is an expert in hip and knee replacement, hip arthroscopy, cartilage preserving and restoring procedures of the knee and non-operative management of hip and knee disorders. He received his medical degree at New York University School of Medicine, completed a residency in orthopedic surgery at the Hospital for Joint Diseases Orthopaedic Institute and a fellowship in hip and knee surgery at the Insall Scott Key Institute. He sees patients at 24 Saw Mill River Road in Hawthorne (914-631-7777). 


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