Runner's Knee: Your Questions Answered

Patellofemoral pain explained

Runner's knee, known clinically as patellofemoral pain, is pain felt around or behind the kneecap (patella), where it glides over the thigh bone (femur). It is one of the most common causes of knee pain. An estimated 1 in 5 people in the general population experience it in a given year, rising to nearly 3 in 10 among adolescents [1]. Below are the questions people most often ask about it. Numbers in square brackets refer to the reference list at the end.

1. What causes pain at the front of my knee when I run?

Patellofemoral pain develops when the joint between the kneecap and thigh bone is under more load than it can currently tolerate. Symptoms are typically aggravated by activities that load the knee in a bent position, such as running, squatting, using stairs, jumping and prolonged sitting [2].

In runners, the most common trigger is a rapid change in training: increasing distance, pace, frequency or hill work faster than the knee can adapt [2, 4].

Importantly, pain does not necessarily indicate structural damage. In most cases it reflects a joint that has become sensitive to load, rather than one that is injured [2].

A physiotherapist can assess your knee, identify which activities and training changes are overloading it, and explain what is happening so you can stay active with confidence.

2. Should I stop running completely?

In most cases, no. Complete rest is rarely necessary; the aim is to modify training load rather than stop altogether [4].

A randomised controlled trial of 69 runners with patellofemoral pain found that structured guidance on managing symptoms and adjusting training load was highly effective, and should be a central part of treatment [4]. Your physiotherapist can tailor these changes to you, for example by adjusting weekly distance or frequency, temporarily limiting hills and downhill running, and planning a gradual return to your usual training.

Your physiotherapist can also help you set safe limits for running with some discomfort, and adjust your plan as your symptoms change.

3. How long does runner's knee take to get better?

Recovery times vary, and there is no fixed timeframe. Most people improve with a structured exercise programme and appropriate changes to activity, guided by a physiotherapist [2, 3].

However, it is not always a short-lived problem. One follow-up study found that 57% of participants reported an unfavorable recovery 5 to 8 years after diagnosis. Having symptoms for longer than 12 months before treatment was one of the strongest predictors of a poor long-term outcome [5].

Early assessment by a physiotherapist is therefore preferable to waiting for symptoms to resolve on their own.

4. What are the best exercises for runner's knee?

Exercise therapy is the best-supported treatment for patellofemoral pain [2, 3]. The strongest evidence favors combining hip-focused and knee-focused strengthening, rather than either one alone [3].

Every runner is different, so there is no single programme that suits everyone. Your physiotherapist will assess the strength and control of your hip and knee, along with the activities that aggravate your pain, and will provide you with a tailored set of exercises. These are started at a level the knee can tolerate and progressed gradually as it improves [2, 3].

5. Why does my knee hurt on stairs, when squatting or after sitting for a long time?

These activities increase the force through the joint behind the kneecap while the knee is bent, loading the sensitive area [2]. Pain after sitting for long periods with the knees bent, sometimes called the "cinema sign", is a characteristic feature of the condition [2].

Practical tips: change position or straighten the leg regularly when sitting, and take stairs one step at a time during flare-ups. Your physiotherapist can advise on managing these everyday activities while your knee recovers.

6. Will a knee brace, taping or insoles help?

These can help in the short term, but they are most effective when used alongside an exercise programme rather than in place of one [2, 3]:

• Foot orthoses (insoles): useful to reduce pain in the short term [2, 3].
• Patellar taping: may reduce pain in the short term when combined with exercise [2].
• Knee braces and sleeves: there is limited evidence of benefit, so they are not routinely recommended [2].

7. Is runner's knee arthritis? Will it lead to arthritis?

Patellofemoral pain is not the same as osteoarthritis. In one follow-up study 5 to 8 years after diagnosis, 48 of the 50 participants who had X-rays (98%) had no signs of radiographic knee osteoarthritis [5].

Some research has suggested a possible link between kneecap pain earlier in life and osteoarthritis behind the kneecap later on, but high-quality evidence for this is lacking [6]. Staying active and maintaining leg strength remains the best long-term strategy for knee health [2, 3].

8. Is my kneecap out of line? Do I need to strengthen my "VMO"?

This is a common misconception. Patellofemoral pain does not usually mean the kneecap is "out of place" or needs to be realigned [2].

Many people are advised to target the vastus medialis oblique (VMO), one part of the quadriceps. Current evidence supports general strengthening of the hip and quadriceps muscles, rather than attempting to isolate a single muscle [2, 3]. Your physiotherapist can identify which areas need the most attention in your case and build these into your programme.

9. What role does biomechanics play, and can a biomechanical assessment help?

Biomechanics is the study of how the body moves and how forces pass through the joints. The way you run influences how much load goes through the joint behind the kneecap, so it can be an important piece of the puzzle in runner's knee.

Research shows that runners with patellofemoral pain, particularly women, often move differently from runners without pain. Common differences include the thigh moving further inwards, the thigh rotating inwards, and the opposite side of the pelvis dropping as the foot lands [7]. Whether these patterns cause the pain or develop because of it is not yet fully clear [7, 9].

Small changes to running technique can reduce the load on the knee. For example, increasing step rate (cadence) by around 10% has been shown to reduce peak force through the joint behind the kneecap by about 14% [8]. Running retraining has also been linked with improvements in pain and function, and with less inward movement at the hip [7].

How a biomechanical assessment can help

A biomechanical assessment by your physiotherapist looks at how you run, alongside your strength, flexibility, movement control and training history. It can help to:

• identify movement patterns or strength deficits that may be increasing the load on your knee
• decide whether changes to running technique, such as adjusting cadence, are likely to help you
• tailor your exercise programme to your specific needs
• provide a baseline to measure progress and guide a safe return to running

Technique changes work best as part of a wider plan. In one trial, gait retraining successfully changed how runners moved, but did not improve symptoms beyond guidance on managing training load [4]. A biomechanical assessment is therefore most valuable when your physiotherapist combines its findings with load management and strengthening, rather than focusing on technique alone.

When to see a physiotherapist

Consider booking an assessment if your knee pain:

• has persisted for more than a few weeks
• is limiting your running, work or sleep
• keeps recurring

Seek prompt medical attention if the knee is hot, red or significantly swollen, if it locks or gives way, or if pain began after a fall or twisting injury.

References

1. Smith BE, Selfe J, Thacker D, Hendrick P, Bateman M, Moffatt F, Rathleff MS, Smith TO, Logan P. Incidence and prevalence of patellofemoral pain: a systematic review and meta-analysis. PLoS ONE. 2018;13(1):e0190892. doi:10.1371/journal.pone.0190892
2. Willy RW, Hoglund LT, Barton CJ, Bolgla LA, Scalzitti DA, Logerstedt DS, Lynch AD, Snyder-Mackler L, McDonough CM. Patellofemoral pain: clinical practice guidelines linked to the International Classification of Functioning, Disability and Health from the Academy of Orthopaedic Physical Therapy of the American Physical Therapy Association. J Orthop Sports Phys Ther. 2019;49(9):CPG1–CPG95. doi:10.2519/jospt.2019.0302
3. Collins NJ, Barton CJ, van Middelkoop M, Callaghan MJ, Rathleff MS, Vicenzino BT, Davis IS, Powers CM, Macri EM, Hart HF, de Oliveira Silva D, Crossley KM. 2018 Consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain: recommendations from the 5th International Patellofemoral Pain Research Retreat, Gold Coast, Australia, 2017. Br J Sports Med. 2018;52(18):1170–1178. doi:10.1136/bjsports-2018-099397
4. Esculier J-F, Bouyer LJ, Dubois B, Fremont P, Moore L, McFadyen B, Roy J-S. Is combining gait retraining or an exercise programme with education better than education alone in treating runners with patellofemoral pain? A randomised clinical trial. Br J Sports Med. 2018;52(10):659–666. doi:10.1136/bjsports-2016-096988
5. Lankhorst NE, van Middelkoop M, Crossley KM, Bierma-Zeinstra SMA, Oei EHG, Vicenzino B, Collins NJ. Factors that predict a poor outcome 5–8 years after the diagnosis of patellofemoral pain: a multicentre observational analysis. Br J Sports Med. 2016;50(14):881–886. doi:10.1136/bjsports-2015-094664
6. Thomas MJ, Wood L, Selfe J, Peat G. Anterior knee pain in younger adults as a precursor to subsequent patellofemoral osteoarthritis: a systematic review. BMC Musculoskelet Disord. 2010;11:201. doi:10.1186/1471-2474-11-201
7. Neal BS, Barton CJ, Gallie R, O'Halloran P, Morrissey D. Runners with patellofemoral pain have altered biomechanics which targeted interventions can modify: a systematic review and meta-analysis. Gait Posture. 2016;45:69–82. doi:10.1016/j.gaitpost.2015.11.018
8. Lenhart RL, Thelen DG, Wille CM, Chumanov ES, Heiderscheit BC. Increasing running step rate reduces patellofemoral joint forces. Med Sci Sports Exerc. 2014;46(3):557–564. doi:10.1249/MSS.0b013e3182a78c3a
9. Neal BS, Lack SD, Lankhorst NE, Raye A, Morrissey D, van Middelkoop M. Risk factors for patellofemoral pain: a systematic review and meta-analysis. Br J Sports Med. 2019;53(5):270–281. doi:10.1136/bjsports-2017-098890

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