Runner’s knee encompasses several conditions causing knee pain, including patellofemoral pain syndrome and chondromalacia patella. There are different causes and treatments which will be discussed.
For traumatic injuries causing fractures, dislocations, or tearing of the ligaments and cartilage, we refer you to our article on adult knee pain. This paper will focus specifically on runner’s knee and its associated conditions, like iliotibial band syndrome.
What structures are important in a runner's knee?
The above image shows the structures of the knee; it is the right knee, and the vantage point is from the outside of the knee. In this image, you can see the knee structures necessary for understanding runner’s knee, including:
- Femur or thigh bone
- Patella or kneecap
- Tibia or shin bone
- Fibula, also known as the outer calf bone
- The quadriceps tendon where the four muscles of the thigh (quadriceps) attach to the kneecap
- The patellar tendon is actually a ligament since it connects two bones (patella and tibia)
- Articular cartilage at the end of the tibia bone
What is a runner's knee?
In the literature, the terms runner's knee, patellofemoral pain syndrome, and chondromalacia patella are used interchangeably. Even though they are slightly different, they all involve pain in the knee area.
Patellofemoral pain syndrome (PFPS) is pain at the patella or femur; it worsens with prolonged activity or inactivity (with the knee bent).
Chondromalacia patella is knee pain resulting from erosion (wearing down) of the articular cartilage, seen on the underside of the patella in the diagram above. The articular cartilage is made of hyaline, while the meniscus cartilage is made from fibrocartilage, a distinct type of thick cartilage that functions as a shock absorber in the knee.
What are the symptoms of a runner's knee?
Note that the pain of a runner's knee can occur quickly or develop slowly over time; it is usually a dull ache at the anterior (front) knee area. The pain worsens when there is increased mechanical stress on the knee joint. Occasionally, the symptoms appear after prolonged sitting with the knee bent.
What causes a runner's knee?
Runner's knee can not only be caused by running but also by jumping, climbing stairs, and squatting. All these activities cause microtrauma (trauma at the tissue level).
Other causes of runner’s knee include:
- Thigh muscles that are too tight or loose
- Cartilage degeneration from physician injections
- Flat feet (pes planus)
- Poor or improper footwear
- Running on hard surfaces
- Patellar tracking disorder, in which the patella does not move properly when the knee is flexed (bent) and extended (straightened)
What is iliotibial band syndrome?
A discussion of runner’s knee would not be complete without a discussion of iliotibial band syndrome since it's common in runners. The iliotibial band is a thick band of elastic connective tissue, called fascia, that runs (no pun intended) from the hip to just below the knee (see diagram below).
Its cause is believed to be related to the friction between the iliotibial band and the outside of the distal femur (see the inflamed area in the diagram).
What is the diagnostic workup for runner’s knee?
The history of running and other athletic activities is essential.
Physical exam checks for areas of knee tenderness or swelling. When chondromalacia patella is present, movement can produce grinding or crepitus, a cracking noise produced with knee flexion and extension due to air entering the injured knee's soft tissues.
Laboratory tests should be done to rule out certain conditions, including infection, rheumatoid arthritis, and gout.
Imaging studies such as plain x-rays should be done to evaluate for bony abnormalities, including fractures, osteoarthritis, spurs, or osteoporosis (bone thinning).
Computed tomography (CT) and magnetic resonance imaging (MRI) scans evaluate soft tissue structures not seen on x-rays, including the muscles, tendons, and ligaments; in addition, they provide a more detailed view of the bones. Currently, MRI is the gold standard for knee evaluations.
What are the treatments for runner’s knee?
Treatments are like those for other musculoskeletal disorders, including medications, physical therapy, ice, heat, braces, or cortisone injection. In addition, there are specific treatments that are designed to treat runner’s knee:
Stretching of the knees and hips is very important before and after running. Unfortunately, many runners do not stretch, and those that only stretch the knee area do not realize how the muscles attaching to the hip can lead to knee pain, including the iliotibial band.
Quality running shoes can alleviate the symptoms of a runner's knee, especially in people with flat feet (pes planus). Unfortunately, some runners do not regularly replace their sneakers, leading to knee issues. Wearing old or worn sneakers is one of the major causes of iliotibial band syndrome. Different brands of sneakers are designed for various foot sizes and shapes; thus, we recommend that all runners have a proper foot and sneaker evaluation.
Patellar taping can help runners with patellar tracking issues. For these people, medical tape is used to stabilize the patella.
Foot orthotics (sneaker inserts), either over-the-counter or custom-made, can effectively treat a runner's knee. Sometimes, over-the-counter orthotics provide the needed relief, while firm custom orthotics lead to knee pain and vice versa. In addition, every person is different and will respond differently to over-the-counter vs. custom orthotics.
The term runner's knee, patellofemoral pain syndrome, and chondromalacia patella are used interchangeably, even though there are some slight differences.
As the name implies, runner's knee is associated with running but can also be caused by other activities.
Iliotibial band syndrome occurs on the outside of the knee and is often associated with runner's knee.
There are many specific treatments for runner's knee, including stretching the knees and hips, obtaining quality running shoes, patellar medical taping, and orthotics (sneaker inserts).
National Library of Medicine. Chondromalacia Patella.
Annals of Translational Medicine. Evidence Based Treatment Options for Common Knee Injuries in Runners.
National Library of Medicine. THE MANAGEMENT OF ILIOTIBIAL BAND SYNDROME WITH A MULTIFACETED APPROACH: A DOUBLE CASE REPORT.
Journal of Orthopaedic & Sports Physical Therapy. Patellofemoral Pain.