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How A Preoperative Knee MRI Help Diagnose Patellofemoral Joint Syndrome?

Patellofemoral Syndrome or Runner’s Knee is the most common cause of knee pain and is caused by overuse or trauma to the patella or kneecap.

According to the American Academy of Family Physicians, 11% of all musculoskeletal complaints are linked to anterior knee pain. PFPS (Patellofemoral pain syndrome) constitutes 16-25% of all injuries in runners.

Facts on Patellofemoral Syndrome:

  • The most obvious symptom is a dull, aching pain in the kneecap or front of the knee.
  • PFPS occurs when the nerves in the kneecap sense pain.
  • PFPS diagnosed based on a physical exam and medical history.
  • Surgery is a last resort and happens in cases where non-invasive treatments have failed.

What is PFPS or Patellofemoral Syndrome?

PFPS or Patellofemoral Syndrome is an injury that patients describe as pain in the front of the knee or around the kneecap and is also known as runner’s knee or jumper’s knee. Imbalances in the patellar tracking during the extension and flexion of the knee joint causes the condition.

The patellofemoral joint comprises of the patella and femoral trochlea, where the patella acts as a lever and increases the movement of the joint, the quadriceps and patellar tendons. When excess pressure or overloading occurs on the joint, pain behind or around the patella is experienced.


The main symptom associated with PFPS is a dull, aching pain in front of the knee, that worsens with walking or climbing stairs. Some patients can feel other symptoms such as stiffness or pain due to prolonged sitting (called ‘theater sign’) or sharp pain in the anterior knee.

Patients might complain of the knee giving way, but this is not a symptom of Patellofemoral Syndrome. But it is essential to determine if patellar subluxation has occurred, as patellar instability can be associated with PFPS.

Since PFPS or Patellofemoral Syndrome occurs due to overuse or intensity of training, other possible contributors can include inappropriate or overworn footwear, and excessive lower extremity resistance training such as squats and lunges.


There is no particular cause or specific reason for patellofemoral pain syndrome or PFPS. However, it is often associated with:

  • Repetitive Stress on Joint: Repetitive stress applied on the knee joint leads to the development of patella. Sports such as running or jumping can add excess pressure on the joints.
  • Muscle Imbalance: PFPS can occur when the muscles around the hip and the knee are not in proper alignment with the kneecap. As a result, excess pressure on the patella joint can cause pain.
  • Prior Injury: A history of injuries that includes dislocations, trauma, or surgeries, can cause damage to the articular cartilage or alter the patellofemoral joint, which can result in anterior knee pain.
  • Surgery: Knee surgery or any repair to the anterior cruciate ligament can increase the risk of patellofemoral pain.
  • Change in Training Regime: Changes in extremity resistance training or conditional exercises such as squats or lunges can increase the chance of a patellofemoral injury.
  • Overworn Footwear: Excessively overworn footwear or footwear that is not the right size can affect the nerves and put pressure on the kneecap.

Risk Factors

Several risk factors can create a predisposition for the development of PFPS. Age, Sex, and individual sports are the main contributing risk factors for patellofemoral pain.

PFPS Risk Factors:

  • Age: PFPS occurs mainly in adolescents and young adults. Knee pain in the older population is primarily due to arthritis.
  • Sex: Women are twice as likely to develop patellofemoral pain than men. Because women’s wider pelvis increases the angle at which the bones meet at the knee joint.
  • Specific Sports: Running, jumping, lunging increases the stress on the kneecap, especially when there is a sudden increase in training levels.
  • Muscle Dysfunction: Weakness in quadriceps or irregular firing patterns in the joint can increase the risk of PFPS.
  • Lower Extremity Misalignments: Abnormalities such as pes planus, or subtalar pronation has been linked as a risk of PFPS.
  • Patellar Hypermobility: Loose joints or double-jointed people have a range of motion beyond normal. But this can cause more injuries such as patellar hypermobility.
  • Flat Feet: People with flat feet are at a higher risk of developing PFPS as added stress impacts their knee joints.

Diagnosing Patellofemoral Pain Syndrome

Doctors usually diagnose PFPS by conducting a physical exam and checking medical history.

To assess the exact location of the pain, the doctor will ask you to squat, jump, or bend to test your knee and core body strength. To rule out any other physical problems, the doctor may also check:

  • Postural alignment of the kneecap with the lower leg
  • Stability of the knee, hip rotation and range of motion in the knee and hip
  • Attachment of the thigh muscles to the kneecap
  • Strength, firmness, the flexibility of bones, quadriceps, and hamstrings
  • The tightness of the heel and latitude of the feet
  • Walking or gait of the patient to see if excess pressure impacts the knee

The doctor may also recommend a Knee MRI to help diagnose the exact location of the injury.

What is a Knee MRI?

Since the discovery of the Magnetic Resonance Imaging Machine or MRI, it has become the standard scanning procedure for evaluating injuries to the knee non-invasively. Due to its perfect soft-tissue contrast, high spatial resolution, and multiple images, MRI provides a detailed depiction of the anatomy and can change the initial diagnosis and subsequent treatment plans for over 50% of knee trauma cases.

How to Prepare for a Knee MRI?

Like all MRI Scans, a Knee MRI is a non-invasive outpatient procedure that does not require any preparation unless it is a particular case.

When you visit the hospital or radiology center to schedule a knee MRI, the attendee will ask you a series of questions that pertain to the scan.

You should let them know if you have any:

  • Health problems like kidney or liver diseases,
  • Recently had surgery,
  • Are allergic to iodine or any other substance,
  • Are pregnant or suspect pregnancy

Also, no metals are allowed in the MRI room due to the magnetic field of the MRI machine that attracts metal. It is best to inform the technician or doctors if you have:

  • Artificial Heart Valves
  • Cochlear Implants
  • Implanted Nerve Stimulator
  • Insulin Pump
  • Pacemaker or Implantable Cardioverter-defibrillator (ICD)
  • Metallic pins or screws
  • Metal joints or limbs
  • Metallic fillings or dental implants
  • Drug pumps
  • Metal fragments such as bullets or shrapnel
  • Worked in a metal factory and were exposed to metallic dust
  • Body piercings
  • Tattoos

If you are Claustrophobic or suffer from anxiety, then inform the radiologist or technician, and you might require taking a sedative before the test.

You can also avail Open MRI systems or Positional MRIs that are built especially for Claustrophobic and anxious patients.

Open MRI Scans Better for Diagnosing PFPS?

A conventional knee MRI is usually performed in a standard supine position where no weight-bearing pressure is put on the joint. But, to understand the natural motion of the joint, weight-bearing conditions need to be created.

It is quite challenging in standard MRI machines that are closed-tunnel. But with recent evolutionary changes, the Open MRI systems have been built to overcome these limits.

In Open MRI systems, the magnets are placed in such a way to allow imaging in weight-bearing positions like upright or sitting or bending.

Such postural changes allow flexion and extension of the patella and femoral trochlea that can bring clarity to the location and depth of injury.

Treating Patellofemoral Pain Syndrome:

If a patient is diagnosed with PFPS or Patellofemoral pain syndrome, then the treatment process should focus more on comprehensive rehabilitation, and proper communication must be maintained with the patient to comply with the process.

Physical Therapy

A well-structured rehabilitation program is a primary method of treating PFPS. The program can differ from patient-to-patient and can focus more on correcting the stress on the patella or improving quadriceps or increasing quadriceps flexibility.

A detailed assessment of the patellar imbalances must be conducted to recommend specific exercises that patients can practice at home.

Rest Period

Reducing the load on the patellofemoral joint and its surrounding soft tissues is one of the main steps in pain reduction. If resistance training or conditional exercises such as squats or lunges are causing the injury, then alternative activities can be tried.

Bicycling, swimming, or using an elliptical trainer can be opted for other than running or training. Ice or other cold application methods can also be used to reduce pain.

Addressing Underlying Cause

Patients with PFPS need to have their medical history carefully monitored and changes recorded. Changes such as an increase in miles run, or the addition of resistance training exercises that affect the patellofemoral joints, such be monitored as these are the main risks of PFPS.

Other Treatment Methods

Analgesics: Nonsteroidal anti-inflammatory drugs can be prescribed to reduce the pain, but this is only at the initial stage.

Bracing: A variety of braces, straps, sleeves can be prescribed to provide symptomatic relief of PFPS.

Patella Taping: Patella taping improves the alignment of the kneecap with the leg and increases the quadriceps function and can be used as an initial treatment process for PFPS patients.

But, these treatment methods need to be followed with physical therapy parallelly as individually, these treatment methods have no research to prove that they work alone.

Surgical Consultation

After a patient completes 6-12 months of a thorough rehabilitation program but is still in pain, then a surgery consultation can be recommended. Surgical options include articular cartilage procedures, proximal or distal realignment, and lateral retinaculum. In the case of surgery, most doctors recommend a visit to a specialist and a knee MRI just to make sure that the pain is not due to other underlying issues.

Preventing Patellofemoral Syndrome

Patellofemoral Syndrome is painful and debilitating - and not all cases can be prevented.

But, specific steps can be taken to reduce the risk of further injury to the knee. That includes:

  • Correct Muscle Balance: Muscle imbalance can be reduced if proper muscle balance is maintained. Strengthening knee muscles and increasing knee alignment can contribute to maintaining muscle balance.
  • Correcting Flat Feet: Wearing supportive footwear or shoe inserts can help treat flat feet and reduce stress on the knee joint.
  • Maintaining a Healthy Weight: Increase in weight can add more stress to the joints, and increase the risk of PFPS. Eating healthy and exercising can help in maintaining a proper weight balance, keep the excess weight off the kneecaps.
  • Pre-Workout Warm-ups: It is essential to warm-up before a workout. Stretches, light exercises are crucial just before a workout - they help increase flexibility and reduce the risk of injury.
  • Gradual Change in Training Regiment: Sudden changes in the duration or intensity of workouts can cause knee pain. It is imperative to make incremental changes in training regimes so that the body can adjust to the excess pressure.
  • Avoid Knee Stress: Choosing low knee impact activities like cycling or swimming, wearing supportive footwear, and using knee braces while working out can help reduce the pressure on the kneecaps and legs.


Typically, a patient suffering from patellofemoral pain syndrome can use home treatment options like exercises, stretches, and ice packs to reduce the pain. But older patients or people who have pain in both kneecaps may need to get a knee MRI to check just what is wrong.

Recovery will also depend on the severity of the injury, and the recovery process followed. If proper care is not taken, then a PFPS injury can become a dislocation of the kneecap - which is more challenging to overcome.