Patellofemoral pain syndrome is a syndrome characterized by pain or discomfort seemingly
originating from the contact of the posterior surface of the patella with the femur.
It is a frequently encountered diagnosis in sports medicine clinics.
Causes The cause of pain and dysfunction often results
from either abnormal forces or prolonged repetitive compressive or shearing forces on the PF joint.
The result is thinning and softening of the articular cartilage under the patella and/or
on the medial or lateral femoral condyles, synovial irritation and inflammation and subchondral
bony changes in the distal femur or patella known as "bone bruises".
Secondary causes of PF Syndrome are fractures, internal knee derangement, Osteoarthritis
of the knee and bony tumors in or around the knee.
Diagnosis The diagnosis of patellofemoral pain syndrome
is made by ruling out patellar tendinitis, prepatellar bursitis, plica syndrome, Sinding–Larsen–Johansson
syndrome, and Osgood–Schlatter disease.
Treatment As patellofemoral pain syndrome is the most
common cause of anterior knee pain in the outpatient, a variety of treatments for patellofemoral
pain syndrome are implemented.
However, there is little supporting evidence.
Most patients with patellofemoral pain syndrome respond well to conservative therapy.
Exercises A 2011 systematic review stated that evidence
supports the use of quadriceps exercise for managing patellofemoral pain syndrome and
that quadriceps strengthening is considered to be the "gold" standard treatment for patellofemoral
pain syndrome.
Various exercises have been studied and recommended.
Quadriceps strengthening is commonly suggested because the quadriceps muscles help to stabilize
the patella.
Quadriceps weakness and quadriceps muscle imbalance may contribute to abnormal patellar
tracking.
If the strength of the vastus medialis muscle is inadequate, the usually larger and stronger
vastus lateralis muscle will pull sideways on the kneecap.
Strengthening the vastus medialis to prevent or counter the lateral force of the vastus
lateralis is one way of relieving PFPS.
Moderate evidence supports the addition of hip abductor and external rotator strengthening,
as well as exercises targeting hip flexion and hip extension.
When executing these exercises, proper form is very important in order to ensure that
the musculature is activated in such a way that will not lead to further injury.
Inflexibility has often been cited as a source of patellofemoral pain syndrome.
Stretching of the hip, hamstring, calf, and iliotibial band may help restore proper biomechanics.
Furthermore, the use of a foam roller may help to add flexibility and relieve pain from
sore or stiff muscles in the leg.
A 2013 study showed that high-dose, high-repetition medical exercise therapy was associated with
a decrease in pain and an increase in functional outcome measures.
Medical imaging Magnetic resonance imaging rarely can give
useful information for managing patellofemoral pain syndrome and treatment should focus on
exercise.
In the uncommon cases where a patient has mechanical symptoms like a locked knee, knee
effusion, or failure to improve following physical therapy, then an MRI may give more
insight into planning treatment.
Rest Patellofemoral pain syndrome may also result
from overuse or overload of the PF joint.
For this reason, knee activity should be reduced until the pain is resolved.
Those with pain originating from sitting too long should straighten the leg or walk periodically.
Those who engage in high impact activity such as running should consider a nonimpact activity
such as swimming or aerobics on an elliptical machine.
Ice and medication To reduce inflammation, ice can be applied
to the PF joint after an activity.
The ice should be kept in place for 10 to 15 minutes.
Additionally anti-inflammatory drugs such as NSAIDs can also be taken immediately after
an activity or judicious use during daily activities and for those people whose symptoms
aren't controlled with ice.
Orthosis and taping In addition to physical therapy, external
devices such as patellofemoral knee orthosis and tape could be used to stabilize the knee.
Current medical evidence is not sufficient to describe the extent to which athletic taping
has effects in treating patellofemoral pain.
These orthoses will not correct the underlying source but may prevent further injury.
For this reason, they should be used in conjunction with and not in lieu of physical therapy.
The technique of McConnell taping involves pulling the patella medially with tape.
The underlying goal of taping is multifaceted and intended to correct the position of the
patella, increase vastus medialis oblique activation, and stretch the tight lateral
structures of the patella leading to pain reduction and facilitating strengthening exercises
of the quadriceps.
Studies have shown that patella taping may reduce pain and potentially increase the activity
of the VMO, however the underlying mechanisms of taping are not clearly understood.
Findings from some studies suggest that there is limited benefit with patella taping or
bracing when compared to quadriceps exercises alone.
Arch support Low arches can cause overpronation or the
feet to roll inward too much increasing the Q angle and genu valgum.
Poor lower extremity biomechanics may cause stress on the knees and ultimately patellofemoral
pain syndrome.
Stability or motion control shoes are designed for people with pronation issues.
Arch supports and custom orthotics may also help to improve lower extremity biomechanics.
Epidemiology Specific populations at high risk of primary
Patellofemoral Syndrome include runners, bicyclists, basketball players, young athletes and females.
Typically patients will complain of anterior knee pain or giving away of the knee which
is exacerbated by sports, walking, stair climbing, or sitting for a long time, often called the
"Theater Sign" or "Movie-Goers Sign."
The pain from prolonged sitting is thought to occur because of the constant pull of the
quadriceps muscle on the knee cap while sitting, which causes its impaction against the hard
and unyielding surfaces of the bones of knee joint.
Descending stairs may be worse than ascending.
Unless there is an underlying pathology in the knee, swelling is usually mild to nil.
Palpation, as well, is usually unremarkable.
See also Knee
Knee pain Chondromalacia patellae
Plica syndrome Iliotibial band syndrome
References
External links Patient handout for patellofemoral pain syndrome
by the American Academy of Family Physicians Runner's Knee Prescribe Treatments for patellofemoral
syndrome on PrescribeExercise.com Patellofemoral Pain Syndrome by the Institute
for Physical and Sports Therapy Patellofemoral Pain on patient.co.uk
Patellofemoral Syndrome at eMedicine Patellofemoral Joint Syndromes Treatment & Management
at eMedicine