Patellofemoral syndrome (PFS) refers to pain in the knee resulting from physical and/or biomechanical changes to the knee joint at the point where the patella and femur meet. It is associated with stiffness after prolonged sitting, and tenderness when the patella is compressed on the femoral condyles, or with lateral movement. The condition is also known as

• retropatellar syndrome,

• anterior knee pain,

• runner's knee,

• patellar tendonitis or

• jumper's knee.

Causes of PFS may result from abnormal stress on the joint from age associated degenerative changes, injury, and overuse and overload such as repetitive weight-bearing impact. Additional contributing causes may include

• irritation in the soft tissues around the front of the knee;

• repetitive, excessive abnormal forces on the knee such as tibial torsion;

• imbalance;

• exertion such as using stairs;

• abnormal patellar alignment;

• tight heal cords (Achilles tendons); and

• flat feet or muscle weakness.

Furthermore, chronic injury that causes poor biomechanics or improper biomechanics during exercise, biomedical conditions such as pedal hyperpronation or supination, and a large Q angle (quadriceps) greater than 15° may also cause PFS.

A wide pelvis, having a knock-kneed (Genu Valgum) or bow-legged (Genu Varum) stance, obesity, and family history may also contribute to the development of PFS. Individuals who previously had a dislocation, a fracture, or other trauma to the patella may be more likely to succumb to patellofemoral syndrome. The condition is more common in females.

Signs and symptoms include a dull aching pain, and swelling and tenderness under or in the front of the knee that worsens with physical activity. Such activities may include squatting, lunging, kneeling, using stairs, getting out of a chair, and sitting for a prolonged time. There may be a cracking, grating or grinding sensation with knee extension. Pressing the patella against the femur while in knee extension may be painful. Pain may radiate toward the back of the knee. There may be a history of recurrent clicking. PFS may also mimic arthritis of the patella.

Diagnostic testing includes taking a medical history and performing a physical examination. The examination may include assessment of the patella and quadriceps, knee strength, and mobility and alignment of the lower leg. Assessment is also completed for

• knee stability and range of motion of the knees and hips;

• signs of tenderness under the patella;

• attachment of thigh muscles to the patella;

• strength, flexibility, firmness, tone and circumference of the quadriceps and hamstring muscles; and

• tightness of the heel cord and flexibility of the feet.

To rule out damage to the structure of the knee and the tissues that connect to it, X-rays, magnetic resonance imaging (MRI) studies, computed tomography (CT) scans and blood tests may be indicated. X-rays are usually normal, although a special X-ray view of the patella may show arthritic changes.

Management of PFS may depend upon the particular cause of the knee pain, and is usually successful with non-surgical interventions and reconditioning, especially with early treatment. The individual must refrain from any knee pain- causing activities until the pain completely subsides.

Initial treatment may begin using the "RICE" formula. This includes rest to avert putting weight on the painful knee, applying ice or cold packs for short periods several times a day, compression using an elastic bandage such as a knee sleeve or a special brace for knee support, and elevation of the leg to keep the knee raised above the level of the heart. Medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin may be taken to relieve pain. Orthotic inserts may be prescribed to aid in eliminating the pain.

Once pain and swelling subsides, physical therapy may follow. Reconditioning cross-training exercises to regain full range of motion, strength, power, flexibility, endurance, speed, agility and coordination may be helpful. The emphasis of reconditioning is on quadriceps strengthening, hamstrings and calf stretching, hip strengthening, and stretching of the illiotibial band.

Although patellofemoral syndrome usually improves with therapy and pain medications, surgery may be necessary in some cases if the alignment of the patella cannot be corrected with therapy. Depending on the nature of the misalignment, the surgery may be arthroscopic to remove fragments of damaged patellar cartilage, or open for realignment of the patella and reduction of abnormal pressure on cartilage and supporting structures around the front of the knee. Surgery is successful about 90% of the time.

The primary complication is failure of treatment to relieve pain. When surgery is necessary, surgical complications may include infection, failure to relieve pain, and worsening pain. Damage to the knee structures may range from a slight abnormality of the surface of the cartilage to a surface completely worn down to the bone. Misalignment of the patella in conjunction with vigorous activities can lead to chondromalacia patella (see Diagnostic Code: 5099-5014).

• The rating schedule for musculoskeletal was updated on February 7, 2021. Protection still does apply and should be considered with existing evaluations (38 CFR 3.951(a)).

• To properly rate disability, accurate measurement of range of motion is required and must be reported in degrees. The use of a goniometer in the measurement of ranges of leg flexion is indispensable. 38 CFR §4.46 [Accurate measurement]

• A minimum compensable evaluation may be assigned under 38 CFR 4.59 based on subjective painful motion, and does not require objective evidence of painful motion.

     See VAOPGCPREC 9-2004, VAOGCPREC 09-98

• You must ensure that all knee examinations record range of motion findings in both flexion and extension, in accordance with the Disability Examination Worksheets.

• Although it is permissible to assign multiple evaluations under multiple diagnostic codes for a single knee, you must always abide by the amputation rule (38 CFR § 4.68).

• As always, when evaluating knee function, the provisions of 38 CFR § 4.40, 4.45, and 4.59 must be considered.

• Where knee motion is actually impeded by pain, fatigability, weakness, etc., the evaluation assigned based on limitation of motion must consider the level at which motion is limited. For example, if, on examination, a Veteran has full range of knee motion, but on repetitive motion, the knee is actually limited to 10 degrees extension and 45 degrees flexion due to fatigue, a 10% evaluation would be warranted under diagnostic code 5260 and a separate 10% evaluation would be warranted under diagnostic code 5261.

• None.