for patellofemoral pain (knee cap pain)
Patellofemoral pain (PFP) is a condition where pain is felt on the front of the knee, either around or behind the patella. The patellofemoral joint is part of the knee joint, where the kneecap (patella) sits within its groove (trochlea) on the front of the thigh bone (femur). A smooth layer of joint cartilage covers the trochlea and the back of the patella to help the joint surfaces glide without friction. There are ligaments that help hold the patella centred on the trochlea, and also several muscles attaching to the patella that move it along the trochlea groove. The patellofemoral joint functions as a pulley system to help the quadriceps muscles straighten the knee most efficiently.
Tell me more about patellofemoral pain
PFP is a condition where pain is felt on the front of the knee, either around or behind the patella. It is commonly felt with activities such as squatting, running, jumping and going up or down stairs; often limits a person’s ability to participate in their chosen activity or work; forms 25–40 per cent of all knee presentations to a sports injury clinic, and can affect people of any age, though studies have shown up to one-third of adolescents report PFP.
What causes patellofemoral pain?
Patellofemoral pain occurs due to a variety of reasons. In some cases, there is no particular trigger or injury, though in others, pain may arise after a change in knee loading (eg, suddenly increasing sporting activity, running more on hills or after a growth spurt). In other people, their PFP arises after a separate injury or surgery (eg, following an ACL reconstruction).
Though each person with PFP may have different contributing factors to their condition, there is strong evidence for the most-common reasons. These include:
- Weakness of the front of thigh (quadriceps) muscles: this can cause the patella to not glide centrally within its groove, leading to areas of increased pressure or friction in the patellofemoral joint.
- Weakness in the hip/buttock (gluteal) muscles: this can contribute to poor alignment of the leg and knee, or excessive tightness of other thigh muscles- both of which place extra stress on the patellofemoral joint.
- Variations in bony anatomy: for example, this could be a kneecap that sits high or wide (laterally) in its groove; a trochlea groove that is relatively shallow; or variations of the shape of the hip and thigh bone that cause the knee to turn inwards with walking. In some people, additional factors may include foot posture (eg, flat feet), weak calf muscles, a stiff ankle, hip or knee joint, or tightness of the muscles and other tissue on the outside of the thigh.
Though not classically PFP, there are two other conditions affecting the patellofemoral joint that can cause pain in the same area and lead to similar functional limitations:
- Patellofemoral osteoarthritis: OA can affect the patellofemoral joint, and is as common as tibiofemoral (the bigger part of the knee joint) OA, though they often occur together. The symptoms are similar in nature to PFP.
- Patellar instability: some people have had dislocations of their patella, leading to pain and ongoing instability. There are some similarities between the management of people with patellar instability and those with PFP, though, depending on the degree of instability, the opinion of an orthopaedic surgeon may need to be sought.
How do I know if I have patellofemoral pain?
PFP generally causes a fairly typical pattern of symptoms, though there is no single test used to diagnose PFP. As such, the Patellofemoral Consensus Statement says that the definition of patellofemoral pain is: pain around or behind the patella, or pain that is made worse by at least one activity involving a bent knee and body weight on the leg (eg, jumping, hopping, running, going up or down stairs, or squatting).
Though not required for a diagnosis, people with PFP also commonly experience: grinding sensations from the patellofemoral joint with knee bending, tenderness when the back of the kneecap is touched during an examination of your knee, mild knee swelling, front-of-knee pain while sitting, getting out of a chair, or on straightening your knee after prolonged sitting.
Scans (including X-rays and MRI) are not required to diagnose PFP and your physiotherapist or sports doctor can diagnose PFP with an assessment in the clinic.
How can physiotherapy help with patellofemoral pain?
One of the most important parts of managing PFP is to first have an accurate diagnosis of your knee symptoms. Your physiotherapist can ensure your symptoms are coming from your patellofemoral joint and not due to a different condition (knee osteoarthritis, a cartilage injury or a tendon condition). Following diagnosis, 2015’s evidence-based ‘Best Practice Guide to Conservative Management of Patellofemoral Pain’ states that the key components of PFP treatment include:
This allows each person to understand their condition and their individual contributing factors in order to have realistic expectations of rehabilitation, to manage their activity appropriately, and to actively participate in their treatment.
Individually tailored treatment
This is a physiotherapy program that targets the individual person’s PFP and each of their contributing factors. There is strong evidence to support tailored physiotherapy (including exercise, education, taping and moulded shoe inserts), compared to placebo (flat shoe inserts) in the short (six weeks) and long-term (one year).
There is very strong evidence to support thigh muscle (quadriceps) strengthening exercise and growing evidence to support buttock muscle (gluteal) strength exercise. Results include large reductions in PFP and improved knee function. Good technique with exercise is important, hence mirrors and supervision can help with exercise in the short term. It is very important that a person do their home exercises regularly as prescribed in order to get the best effect. Neuromuscular control (coordination and leg positioning) exercises, especially combining hip and knee alignment, help to learn correct movement patterns. There is evidence to show benefit of trunk/abdominal and calf muscle strengthening exercise in people who have shown weakness in these areas on assessment. There is also a role for stretching, especially of hamstrings and calf muscles if these are found to be tight on assessment.
Patella taping and bracing has been shown to help provide immediate pain relief in many individuals, hence your physiotherpist can show you how to do this yourself.
Shoe inserts (foot orthoses)
These have been shown to help with short-term pain relief in patients with certain foot types. Your physiotherapist can discuss whether orthotics are suitable for you and either provide them or refer you to a podiatrist.
Massage and dry needling can be considered in people with excessive muscle tightness (eg, of the outer thigh muscles) to improve kneecap positioning and gliding.
The expert physiotherapists contributing to the Best Practice Guide discussed the potential role for retraining an individual person’s walking and running technique if required, though evidence for this is currently lacking.
How effective is physiotherapy for treating patellofemoral pain?
There is a large and growing amount of research evidence to support the use of physiotherapy in the treatment of PFP. Although this evidence can’t provide a one-size-fits-all recipe for the treatment of PFP, as each person is unique, there are definitely components of PFP management that apply to most cases and are supported by high-quality research.
The International Patellofemoral research group made six consensus statements based on the current scientific evidence and their expert opinions. These are:
- Exercise therapy has been shown to reduce patellofemoral pain in the short (less than six months), medium (6–12months) and long-term (greater than 12 months). It has also been shown to improve knee function in the medium and long-term.
- A combination of hip and knee exercise has demonstrated better effectiveness than knee exercise alone. This combination has been shown to improve function and reduce pain in the short, medium and long-term.
- Physiotherapy consisting of a combination of methods is recommended to reduce PFP in the short and medium term.
- Short-term pain relief has been demonstrated with the use of shoe inserts.
- There is no evidence to support the use of patellofemoral or knee mobilisation (hands-on movement of the kneecap) or lower back mobilisation, and, as such, these are not recommended for the treatment of PFP.
- Electrotherapy (ultrasound and other electrical machines) are not recommended as part of the management of PFP.
The research also states that PFP treatment is most effective if a person takes an active role in managing their PFP, rather than relying on a healthcare professional to just apply passive treatment to them. If a person completes their home exercise program regularly, as prescribed, and is sensible about building up their activity gradually, this is also effective. Additionally, as PFP normally has several contributing factors, a combined physiotherapy approach best allows each of these contributors to be addressed. This may also include patellofemoral taping, bracing or running retraining.
What can I do at home?
Once you have been diagnosed with PFP there are a few important things to consider in terms of home management.
It’s important to have a good understanding of your PFP in order to appropriately manage your symptoms and activity levels. It is always better to progress daily activity and sport gradually, as sudden increases can lead to flare-ups of pain. Following pain flare-ups, people tend to completely rest and, once settled, they rapidly increase their activity again. This ‘rollercoaster-ing’ cycle of pain and activity is important to break in order to make real progress with your PFP.
In the short term, you may need to reduce certain activities that are aggravating your PFP in order to allow it to settle. This may include reducing running and jumping exercise or taking the lift instead of the stairs.
It is important that any home exercises prescribed by your physiotherapist are done regularly (as prescribed). Research has found a link between the number of rehabilitation exercise sessions done per week at home with a reduction in symptoms.
People who have a foot contribution to their PFP (flat feet) may have shoe inserts prescribed by their physiotherapist or podiatrist. In this case, it’s important to wear the shoe inserts and well-fitting shoes while you’re being active (eg, these people sometimes notice a flare-up of their PFP if they wear thongs all summer).
If your physiotherapist has taught you to tape your patellofemoral joint, you can do this yourself for pain relief (while playing sport or with daily activity).
As there is evidence demonstrating that PFP can go on for many months or even years in some cases, it’s important to maintain a good level of strength in your quadriceps and gluteal muscles to keep your patellofemoral joint functioning as well as possible and reduce the chance of your PFP recurring. As such, once you have finished treatment with your physiotherapist, make sure you have a plan for ongoing maintenance. This may include gym or home exercises to prevent losing the strength and control that you’ve worked hard to build.
How long until I feel better?
As our understanding has grown, it has become clear that PFP is not necessarily something that will disappear on its own, and some people can have episodes on and off for many years. As such, in order to have the best chance of recovering from your PFP and reducing the likelihood of it recurring, it is important to understand your condition, your individual contributing factors and what you can do.
For many people, a program of ongoing and progressive exercise (as prescribed by your physiotherapist) is necessary to build and maintain muscle strength, and good movement coordination. Additionally, there is evidence suggesting that people with PFP may have an increased risk of going on to develop patellofemoral osteoarthritis (OA). Therefore, seeing an experienced physiotherapist for a management program will help you keep your patellofemoral joints functioning as well as possible, and keep you as active as you’d like to be now and into the future.