Research looks at the psychological aspects of patellofemoral pain

Patellofemoral pain (PFP), also known as runner’s knee, is pain in the front of the knee around the kneecap (patella) where it meets the thigh bone (femur). The knee pain often increases with activities that include running, squatting, kneeling, or climbing stairs.

The condition affects females twice as often as males, and while the pain can develop at any age, almost 1 in 3 adolescents (12-17 years old) will experience PFP.

Often, the pain can drastically affect a person’s ability to participate in sports and social activities. Therefore, it is important to effectively treat the condition to improve a person’s quality of life.

Causes of PFP

Unfortunately, there is no single known cause behind the condition and the related pain.

Research has suggested several potential underlying causes that include:

• Patella maltracking: Maltracking occurs when the kneecap (patella) does not glide through the center of the knee joint but instead moves toward the outside of the knee during movement.
• Hip strength and valgus alignment: The weaker the hip strength (gluteus medius and minimus muscles), the greater the risk of valgus knee (knocked knee) alignment, which stresses the knee joint.
• Hamstring tightness: Increased muscle tightness of the back of the leg can also stress the kneecap and its supporting structures.
• Knee-spine syndrome: In patients over 70, a reduced curvature of the lower back (lumbar spine) is associated with increased PFP and is termed knee-spine syndrome.  
• Joint overload: Overload of the knee or patellofemoral joint can occur from high-intensity training and leads to overuse of the joint, eventually causing pain.

Because of the variation in possible causes, effective treatment can be difficult. Studies have shown that 51-91% of adolescents experiencing PFP that are treated with physical therapy do not experience significant improvements.

A focus on psychological factors

Similarities in pain coping methods and the overall pain experience have been seen between PFP patients and patients experiencing other types of chronic pain.

Both groups have higher levels of mental distress compared to healthy individuals, with PFP patients reporting both increased pain and reduced function when additional psychological factors are present.

These additional factors include:

• Pain catastrophizing: the degree to which a person attributes a higher level of worry, apprehension, and fear to the pain they feel or anticipate feeling
• Kinesiophobia: fear of movement caused by underlying anxiety about reinjury
• Fear-avoidance: where fear of pain or reinjury leads to avoiding activities

Following an increased awareness of psychological factors in PFP, a recent research study looked at focusing on these 3 factors as part of a treatment plan for PFP in adolescents.

What did the research find?

Participants in the research study (adolescents with PFP between 12 and 17 years old) watched three short educational videos focused on fear avoidance, kinesiophobia, and pain catastrophizing. They also attended a 1-hr exercise-based physiotherapy session twice a week.

On the first day of physiotherapy treatment, participants watched the first video. This video introduced the concepts of fear avoidance, kinesiophobia, and pain catastrophizing.

After the first week of treatment, participants watched the second video. This video discussed pain coping methods and the process of slowly returning to activity.

Participants then watched the last video after two weeks of treatment. This video explained simple cognitive restructuring, and methods that can be used to change harmful thought processes.

In comparison, the control group watched three videos that discussed typical physical therapy information. This included basic leg anatomy and function, and simple knee exercises. They also attended the same physiotherapy sessions.

When the two groups were compared, both groups had improved function and pain after receiving physiotherapy treatment, but those that watched the psychologically-informed education videos had a greater improvement compared to the group that didn’t watch these videos.

These participants showed greater decreased fear avoidance, kinesiophobia, and pain catastrophizing. They also reported a greater decrease in pain associated with their PFP, and improved physical function.

While more research is needed, the results of this study are important and exciting for the field of patellofemoral pain for two reasons. Firstly, they show that understanding the link between pain and the mind is vital for developing effective treatments. Secondly, psychological interventions are most often very time-consuming and require a therapist with specialized training. However, this study showed that patients had positive results even with just three short videos. This indicates that simple, yet efficient treatment options combined with physiotherapy could successfully be developed and used for patients with PFP in the future.

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