Updated: Apr 13, 2021
What is Patello-Femoral Joint Pain Syndrome?
Patellofemoral joint pain (PFJP) is a very common condition causing pain in the front of the knee.
PFJP can be caused by excessive loading to the knee or rapid changes to physical activity.
PFJP can also be caused by poor biomechanics (poor movement). When moving the knee, the kneecap (patella) tracks up and down in a natural groove at the bottom of the thigh bone (femur). When we have poor knee biomechanics it is thought the knee cap moves to the outside of the groove which can cause pain.
Poor knee biomechanics can be caused by:
1) Weakness around the hip muscles.
2) Weakness in the quadriceps muscles (in the front of the thigh).
3) Foot rolling inwards (pronation) as you put weight on your leg.
The kneecap (patella) is triangle shaped and has a layer of cartilage behind it that cushions it against other surfaces. The joint on the back of the patella is shaped similarly to the keel of a boat and this joint sits in a groove at the bottom of your thigh bone (femur). It is mainly held in place by ligaments which are thick, fibrous structures (like a flattened rope) that connect bone to bone.
The muscles at the front of the thigh (quadriceps) come down and merge with the patella ligament and continue to attach on to the top, front bony bit of your shin bone (tibia).
There are also smaller ligaments that come from the sides of the patella and attach onto the bottom of your femur and the top of your tibia.
There are fat pads under your patella which allow easier gliding of the bones in your knee joint. If the front fat pad becomes inflamed it can cause knee pain that can masquerade as PFJPS, but this is called Hoffa’s Disease or Fat Pad Syndrome.
Your quadriceps, your iliotibial band (ITB) and the above ligaments can be affected in PFJP.
Causes and Risk Factors
Sports that put a repetitive strain on your knee joint, especially those with a lot of running or jumping, can cause irritation under the patella.
Sudden changes in physical activity where load is increased through the knee joint,. This can also affect people that kneel or squat or use stairs a lot in their job such as plumbers, carpet fitters, nursery workers and primary school teachers.
PFJP can occur in anyone from adolescence and older. Recent studies show it is most common in women aged 50-59 years old but still a high proportion of men also get it (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4458915/). It is also thought to be the most common single diagnosis among runners (https://www.aafp.org/afp/2007/0115/p194.html).
Sometimes it is difficult to identify the cause of PFJP and this is known as an idiopathic or unknown cause.
Other known causes:
Hyperextending through knee joint
Weakened gluteal muscles
Tightness in the iliotibial band, hamstrings (muscles at the back of thigh) or calf muscles
Genu valgum or genu varus (‘knock knees’ or ‘bow legged’)
Pes cavus or pes planus (very high foot arches or ‘flat feet’, respectively).
Most people with PFJP complain of pain under, behind or around the kneecap. Usually the pain comes on gradually but can sometimes be caused by trauma and may affect both knees. Common symptoms are:
Stiffness after prolonged sitting
Pain when running, jumping, squatting or going up/down stairs, prolonged weight bearing through the knee joint or walking on uneven ground
A feeling of instability in the knee
A mild ache that can get stronger and occasionally sharp with aggravating activities.
Generally you would not get swelling, locking or actual giving way of the knee in PFJPS. These signs could indicate a different knee condition.
Assessment/tests/imaging (what to expect)
Your doctor or physiotherapist will have to consider many factors when providing a diagnosis. To do this they will ask questions surrounding your occupation, daily activities and hobbies to determine any patterns or recent changes that could be affecting your knees.
They will ask you for a full past medical history to determine if there could be any other cause of your symptoms so it is important to tell your doctor or physiotherapist if you have any other medical conditions.
During the physical examination your doctor or physiotherapist will conduct a variety of tests to pinpoint the diagnosis. For example your physiotherapist may ask you to squat or stand on one leg to see if this aggravates your knee, they will look at the position of your patella, look for swelling, levels of hypermobility and foot positioning. They will also test the muscle strength in your hips, knees and lower legs, as well as looking at how the joint moves and test for any ligament or cartilage involvement.
Your doctor or physiotherapist may request further imaging to rule out any other cause of your symptoms these may include:
X-rays: these provide clear images of bone in the knee and can help diagnose if there is any osteoarthritis. If your knee pain was caused by a traumatic event and X-ray can also help rule out any bony injury.
Magnetic Resonance Imaging (MRI): an MRI scan provides images of the body soft tissue including muscles and tendons. An MRI can be ordered to determine the extent of inflammation within the tendons or other soft tissues and rule out any other injury.
Surgery is rarely needed for PFJP and is only considered once all other approaches have failed and there is no change, or worsening, of the knee pain.
If the pain is caused by repetitive movements then your therapist may advise rest during periods of aggravation and then pacing your activities so you do not irritate the joint.
Aim for 15-20 minutes of heat (hot water bottle/heat pack/heat bag) or ice (packet of frozen peas wrapped in tea towel) with a 15 minute gap then apply again up to 3 times. Ice is better for the initial stage of pain and can help numb nerve endings or reduce swelling. Heat can soften tight muscles and be beneficial before and after stretching. They can also act as a temporary pain relief. Follow this link to see a hot/cold pack we would recommend: https://amzn.to/3sCtma0
Over the counter pain medications can be effective at managing the pain in your knee but you should always seek advice of your doctor or pharmacist first.
Specific exercises strengthening the quadriceps (front thigh muscles) are probably the most important for PFJPS. Your therapist may also help identify weakness around your hip muscles or look at the biomechanics of your whole leg and work towards optimising your movement patterns so they become less irritating to your knee joint. Watch the video below to see some exercises that can help with PFJPS!
Acupuncture/dry needling and massage
Massage can help if the cause of your PFJPS is due to tight muscles surrounding your knee. However, this should always be accompanied by stretches for you to do at home, to prolong the effects of the massage and maximise the benefits. Acupuncture/dry needling can be helpful if there is persistent tightness in any of the surrounding muscle groups. Watch the video below to see what acupuncture can be performed for PFJPS!
Taping can help improve the biomechanics of the knee cap. Tape is applied to the front of the knee to provide support to the knee cap when moving the knee. The tape can be applied yourself or by your physiotherapist. Follow this video to learn how to apply it yourself! (to purchase the tape used in this video follow this link: https://amzn.to/3dgD7nA )
Recovery time can vary depending on management and the severity of the cause of pain. Generally 3-6 months will be sufficient for straightforward PFJPS. However, the time of recovery may increase if there are other long term medical conditions, if you are a smoker or if you do not do the recommended amount of exercise guided by your therapist. Please discuss any concerns you have over your rehabilitation with your therapist.