- Patellofemoral pain is a common knee condition that affects all ages and lifestyles. It is more prevalent in females, especially those who have weaker quadriceps strength, and participate in a single sport.
- Patellofemoral pain is aggravated by activities that load the knee, such as squatting, prolonged sitting, climbing stairs, jumping and running.
- Progressive exercise therapy with emphasis on both the knee and hip, patellar taping and shoe inserts are effective in improving patellofemoral pain.
Pain in the front of my knee. What can it be?
Patellofemoral pain syndrome (PFPS), also known as “runner’s knee”, is a common knee condition where pain develops slowly at the front of the knee around the kneecap. While PFPS is more common in people who engage in running or jumping sports, it is estimated that PFPS affects up to one in four individuals in the general population.
When does it occur?
PFPS can affect people of all ages, from active young children to more sedentary seniors. PFPS is most prevalent in individuals aged between 12 and 19 years, although it is dependent on the activity level and environmental context.
PFPS usually develops over an extended period of time and is often described as a nagging ache or an occasional sharp pain. The pain tends to be worsened by activities that increase the load on it, such as:
- Prolonged sitting;
- Ascending and descending stairs;
- Jumping; and
- Running, especially with incline.
A study by Collins et al investigated the presence of symptoms in people with PFPS. They found that 93.7% of individuals with PFPS had difficulty squatting, 91.2% had difficulty climbing up and down stairs, and 90.8% had difficulty running. More than half also reported pain during prolonged sitting, with only approximately 20% being able to sit without any pain.
The pain experienced from PFPS is often chronic. There is a significantly high recurrence rate of PFPS, with 70% to 90% experiencing recurrent symptoms. A study found that after four years following diagnosis, 94% continue to experience some degree of pain, and only less than half (46%) had a decrease in pain felt.
Who is more likely to experience pain in the front of the knee?
The cause of PFPS is not completely understood to this date. It is believed that multiple factors contribute to the development of PFPS, rather than a sole cause. The following are some factors that increase one’s risk of developing PFPS:
- Female sex
- Specialising in a single sport
- Quadriceps weakness
PFPS tends to occur more commonly in females than males. 55% of patients with PFPS are female. At the US Naval Academy, PFPS was reported in 15% of female naval cadets compared to 12% of male cadets. Female naval cadets were also 2.33 more likely to develop PFPS when compared with their male counterparts. The prevalence of PFPS in high school female runners is also higher at 21% compared to males (16%). This suggests that physically active women were more likely to develop PFPS compared to physically active men.
Participation in a single sport also increased the risk of developing PFPS. A study that looked into the relationship between sports specialisation and PFPS risk in young female athletes found that there was a higher incidence of PFPS in those who specialised in one sport compared to those who played multiple sports.
Muscle strength is also indicative of the risk of PFPS. Weakness in the quadriceps, the muscles that straighten the knee, is predictive of the development of PFPS. Additionally, beyond the knee, greater muscle weakness in the hip is observed in those with PFPS compared to those without PFPS. Decreased flexibility of the quadriceps, hamstrings and gastrocnemius muscles are also more common in individuals with PFPS.
The development of PFPS is not influenced by height, body weight, leg length or foot posture.
What can help reduce the pain in the front of the knee?
PFPS is not a self-limiting condition, meaning that it will not resolve on its own without treatment. As a result, people with PFPS may experience substantial changes in quality of life, personal identity loss, confusion and fear related to the pain, and uncertainty about the future. Treatment that gradually increases the amount and variety of exercises and activities is essential to improving PFPS.
Exercise therapy is essential in PFPS treatment. Progressive exercise therapy that includes a combination of exercises that target both the knees and hips is preferred over knee-targeted exercises only. Targeting both the hips and knees can help individuals suffering from PFPS to reduce pain and improve outcomes and functional performance in the short, medium and long term. Examples of exercises that work the hips and knees include:
Hip-targeted exercises should focus on strengthening the glutes and hamstrings. Knee-targeted exercises should include both weight-bearing (eg. squats) and non-weight bearing (eg. resisted knee extensions) exercises to strengthen the muscles around the knees. In the early stages of PFPS treatment, more emphasis may be put on the hip-targeted exercises should pain around the knee be severe.
Beyond exercise, other Physiotherapy interventions such as patella mobilisations, patellar taping and stretching may be combined with exercises to produce better outcomes.
Patellar taping combined with exercise therapy is beneficial to relieve immediate pain and improve outcomes of exercise therapy in the short term. However, it was reported that taping may not be effective in the long term (after four weeks) or when performing more intensive exercises. Additionally, taping to improve muscle function is not recommended.
In individuals with PFPS and foot overpronation, shoe inserts may be used together with exercises to reduce pain in the short term (for up to six weeks). There is currently insufficient evidence on the benefits of using custom foot orthoses over off-the-shelf foot orthoses, and therefore both may be used.
What does not help with PFPS?
Passive treatments such as dry needling, isolated manual therapy, neuromuscular electrical stimulation, ultrasound and therapeutic laser are not recommended. Dry needling was reported to not be effective in reducing pain or improving function immediately or after three days post-treatment. The evidence also does not support the use of biophysical agents, which includes ultrasound, cryotherapy, phonophoresis, iontophoresis, electrical stimulation, and therapeutic laser, for the treatment of patients with PFPS as they may not improve outcomes.
Electromyography (EMG)-based biofeedback should not be used on quadriceps activity in addition to knee-targeted exercise therapy when treating PFPS. While it was originally proposed that EMG-based biofeedback can encourage reduced lateral patellofemoral tracking in individuals with PFPS, the evidence suggests that there is no added benefit over just performing knee-targeted exercises.
Patellofemoral knee orthoses such as braces, sleeves or straps are also not recommended for individuals with PFPS, as there is no meaningful impact on pain in the short term.
How long does PFPS take to get better?
PFPS recovery usually takes 12 weeks or more. For those with greater pain levels or had PFPS for more than two months, a longer recovery time is to be expected.
However, a full recovery is possible with progressive loading of the muscles around the hip and knee. With consistent exercise and loading, the gradual resumption of higher-impact sporting activities is possible. Additionally, staying in shape and maintaining a healthy weight can improve long-term recovery.
Willy RW, Hoglund LT, Barton CJ, Bolgla LA, Scalzitti DA, Logerstedt DS, Lynch AD, Snyder-Mackler L, McDonough CM. Patellofemoral Pain. J Orthop Sports Phys Ther. 2019 Sep;49(9):CPG1-CPG95. doi: 10.2519/jospt.2019.0302. PMID: 31475628.
DISCLAIMER: These advice and exercises should not replace the need for a consultation with a Physiotherapist especially if your condition doesn’t improve. Therapeutic exercise should be carefully selected to suit your condition.