Patellofemoral pain

What it is

How consensus statements and reviews define it

The 2016 consensus statement names “patellofemoral pain” as the preferred term¹. It lists patellofemoral pain syndrome, chondromalacia patella, anterior knee pain and runner’s knee as other names for it¹. Its core definition is pain around or behind the patella (kneecap)¹. The pain worsens with one or more activities that load a bent knee under body weight, such as squatting, stairs, running or jumping¹.

A 2015 Cochrane review calls it a common knee problem, mainly in adolescents and young adults⁴. It says the pain comes mostly when the muscles that straighten the knee are loaded, as on stairs or in squats⁴.

An earlier Cochrane review, from 2012, links the pain to changes in the patellofemoral joint, the joint between the kneecap and the thigh bone⁵. It says the pain usually comes on gradually, without signs of other knee diseases or of an injury⁵. The 2016 consensus statement says there is no definitive clinical test for it¹.

The joint and tissues involved

At the patellofemoral joint, the kneecap slides up and down in a groove on the lower end of the femur (thigh bone)⁶.

Engraving of the back surface of the right kneecap, the side that faces the thigh bone. It is labelled with a larger outer facet that meets the lateral condyle of the femur and a smaller inner facet for the medial condyle, with the patellar ligament attached at the lower tip. — The kneecap from behindHenry Vandyke Carter, in Henry Gray, Anatomy of the Human Body (1918), Fig. 256. Public domain, via Wikimedia Commons. (source, Public domain)

Patellofemoral force is the force pressing the kneecap against the thigh bone. A meta-analysis found it higher in activities with more knee bend, such as squatting, than in those with less, such as walking⁷. The same review pooled studies’ estimates of peak force in everyday activities, in multiples of body weight⁷:

Activity	Healthy people	People with patellofemoral pain
Walking	0.9⁷	0.8⁷
Stair ascent	3.2⁷	2.5⁷
Stair descent	2.8⁷	2.6⁷
Running	5.2⁷	4.1⁷

It found no clear differences in everyday activities between healthy people and those with this pain or osteoarthritis (wearing away of joint cartilage)⁷. Among 25,124 knee arthroscopies (keyhole operations inside a joint), articular cartilage damage was most often behind the kneecap (36%)⁸.

Who it affects

How common it is

A 2018 international consensus statement says it affects a large share of people, from adolescents to older adults⁹. Incidence counts new cases over a set time, and person-years multiply people by the years each was followed.

Group studied	What was found
General population and adolescents, in a meta-analysis of 23 studies	Yearly prevalence reported as 22.7% and 28.9%²
Adolescents, in a meta-analysis	Prevalence at one point in time of 7.2%, and 22.7% in female-only groups of adolescent athletes²
1,525 US Naval Academy participants, followed up to 2.5 years	22 new cases per 1,000 person-years¹⁰; women were 2.23 times as likely as men to develop it¹⁰
Military recruits and amateur runners, in an epidemiology review	9.7 to 571.4 per 1,000 person-years in recruits, and 1,080.5 in amateur runners²
Ultra-marathon runners, in a review of running injuries (8 studies, 3,500 runners in all)	Prevalence of 7.4% to 15.6%, one of the two most common running injuries¹¹

Factors studied

Reviews of studies that follow people forward in time have tested which traits come before the pain¹²:

Body size and age: a meta-analysis of 18 such studies found strong to moderate evidence that age, height and weight were not risk factors¹².
Hip strength: a meta-analysis of 18 studies with 4,818 people found moderate evidence against weak hips being a risk factor¹². In adolescents, it found moderate evidence that greater hip abduction strength (moving the thigh out to the side) was one¹².
Thigh strength: a meta-analysis found moderate evidence linking quadriceps weakness with later pain in military groups¹². The quadriceps are the four muscles on the front of the thigh that straighten the knee.
Landing: a meta-analysis found peak inward knee angle on landing did not predict the pain, while lower knee-straightening strength did¹³.
Sport: in the 2016 consensus statement, specialising in one sport went with about 1.5 times the risk of new pain, against playing several¹.

One meta-analysis found lower hip strength in adults with the pain in cross-sectional studies, which measure people at one time¹⁴. Forward-looking studies found no link, which suggests the weakness may follow the pain rather than cause it¹⁴.

What studies found

How it changes over time

A 2016 study noted it was long seen as self-limiting, settling on its own¹⁵. It added that recent studies find many still report knee pain long term¹⁵.

310 people from two trials: 55% had an unfavourable recovery at 3 months and 40% at 12 months³. The authors said this held whatever the intervention³. Pain lasting over 2 months at the start went with an unfavourable recovery at 12 months, and was the most consistent predictor³.
People from two trials, 5 to 8 years on: 34 of 60 who replied (57%) reported an unfavourable recovery¹⁵.
General practice, 172 people aged 12 to 35 with non-injury knee symptoms: in those with this condition, 40% still had symptoms after 6 years¹⁶.
2,200 Danish adolescents aged 15 to 19: this pain was set against other knee pain¹⁷. Knee pain 2 years on was 1.26 times as likely after it¹⁷. They were also more likely to cut back or stop sport¹⁷.

A 2010 review found little high-quality evidence on whether front-of-knee pain in younger adults leads to later kneecap osteoarthritis¹⁸. It found one case-control study linking such pain with later kneecap osteoarthritis, at 4.4 times the odds¹⁸. Six small uncontrolled studies gave rough yearly risks of 0% to 3.4%¹⁸. In the 5-to-8-year follow-up, 48 of the 50 people X-rayed showed no signs of osteoarthritis¹⁵.

What reviews and panels concluded

A 2018 consensus statement, voted on by 41 experts, supported exercise, combined approaches and foot orthoses (shoe inserts) for pain or function⁹. It did not support mobilisations (moving a joint by hand) alone or electrophysical agents (devices that apply heat, sound, light or electricity to the body)⁹. It was unsure about taping, bracing and gait retraining (changing how a person walks or runs)⁹. It was also unsure about acupuncture (needles into set points on the skin) and dry needling (needles into tight spots in muscle)⁹. The same went for blood flow restriction training (exercise with a limb cuff that partly limits blood flow)⁹.

A 2022 meta-analysis of 65 randomised trials found six approaches with positive effects at 3 months¹⁹. None had been adequately tested beyond that point¹⁹. Within 3 months, four beat sham or placebo (dummy versions) or wait-and-see: knee-focused exercise, combined approaches, foot orthoses and lower-quadrant manual therapy (hands-on methods)¹⁹. Hip-and-knee exercise, and knee exercise plus a dextrose (a simple sugar) injection near the nerves, did better than knee exercise alone¹⁹.

A 2024 guide combined 65 high-quality trials with interviews of people with the pain and of clinical experts²⁰. It concluded that exercise and education should come first, with others fitted to the person²⁰.

Exercise and education

2015 Cochrane review: in two pooled studies (166 people), exercise gave about 88 more recoveries per 1,000 at 12 months than control’s 250⁴. The confidence interval (a range showing how precise the result is) ran from 2 fewer to 210 more⁴. It could not tell which form of exercise is best⁴.
Hip and knee strengthening: in a meta-analysis of 14 trials (673 people), this cut pain more than knee strengthening alone²¹. Yet strength did not change significantly in any programme²¹.
131 people, one trial: supervised exercise gave less pain at 3 and 12 months than rest and avoiding painful activity²². Function was better at 3 months but not at 12²². Recovery at 12 months was 62.1% against 50.8%, not a statistically significant difference²².
121 adolescents, one trial: some had education plus 3 months of supervised exercise at school, others education alone²³. The exercise group had higher odds of recovery at 12 months (odds ratio 1.73)²³.

A 2020 review of nine trials found low-credibility evidence that health education material alone did worse than exercise²⁴. Education from a health professional gave outcomes similar to exercise plus education, on low to very low-credibility evidence²⁴.

Foot orthoses, taping and add-ons

A 2011 Cochrane review of two trials (210 people) found foot orthoses had no clear edge over plain insoles²⁵. It said orthoses may ease knee pain in the short term, though the gain may be marginal²⁵. Wearers more often reported mild problems such as rubbing and blisters²⁵. In one trial of 179 people aged 18 to 40, off-the-shelf orthoses gave more short-term gain than flat inserts, notably at 6 weeks²⁶. All four groups in it made clinically meaningful gains over 52 weeks²⁶.

A 2012 Cochrane review of five small trials found no significant difference in pain between kneecap taping and no taping⁵. It judged the evidence low quality and too thin for conclusions⁵.

A 2024 review of 45 trials looked at add-ons to exercise²⁷. Adding taping, whole-body vibration or a knee brace gave no different pain or function than exercise alone²⁷. Adding electrical stimulation (small currents that make a muscle contract) or diathermy (heating deep tissue with electromagnetic energy) brought short-term pain gains²⁷. Both findings rest on very low-certainty evidence²⁷.

Surgery

In a randomised trial of 56 people with long-standing pain, arthroscopy was added to 8 weeks of home exercise²⁸. At 9 months it gave no better knee questionnaire score than exercise alone, and both groups improved markedly²⁸. At 5 years, outcomes were equally good in both groups, and some people in each still had symptoms²⁹. Direct health costs were an estimated 901 euros per person higher with arthroscopy²⁸.

Connections

The pain centres on the patella and where it meets the knee^1,6. The kneecap sits inside the tendon of the quadriceps⁶.

The gluteus medius is the main hip abductor³⁰, and the gluteus maximus extends the hip³¹. In a review of five studies, females with the pain had weaker hip abduction, external rotation and extension on the painful side than healthy controls³². A 2026 review of adult endurance runners looked across this pain, iliotibial band syndrome and patellar tendinopathy together³³. Across them, the leading risk factors were previous injury, more training load and structural malalignment (bones or joints sitting out of their usual line)³³.

In a study of 20 females with the pain and 20 without, the pain group’s knee moved further inward during the single-leg squat³⁴. Among 35 activities tested in 20 healthy people, the single-leg decline squat had the highest kneecap loading score, combining peak and total load³⁵.

For the drop landing, one review noted that a single study found the knee’s inward turning force at first contact predictive¹³. In 44 people with the pain and tight quadriceps, static and dynamic quadriceps stretch did not differ significantly in pain or function³⁶. In a study of 30 people with the pain and 30 without, the pain group had less flexible calves, which relates to the calf stretch³⁷.