Patellofemoral Pain

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For further information, see CMDT Part 41-06: Musculoskeletal Injuries of the Knee

Key Features

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Essentials of Diagnosis

Pain experienced with bending activities (kneeling, squatting, climbing stairs)
Lateral deviation or tilting of the patella in relation to the femoral groove

General Considerations

Also known as anterior knee pain, chondromalacia, or "runner's knee," describes any pain involving the patellofemoral joint
Pain affects any or all of the anterior knee structures, including the medial and lateral aspects of the patella as well as the quadriceps and patellar tendon insertions
Patellofemoral pain is also associated with muscle strength and flexibility imbalances as well as altered hip and ankle biomechanics
Abnormal patellar tracking during flexion can lead to abnormal articular cartilage wear and pain
When the patient has ligamentous hyperlaxity, the patella can sublux out of the groove, usually laterally
There are two common presentations
- Patients whose ligaments and patella are too loose (hypermobility)
- Patients who have soft tissues that are too tight leading to excessive pressure on the joint

Clinical Findings

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Symptoms and Signs

Pain
- Usually occurs in the anterior knee with bending movements and less commonly in full extension
- May sometimes be referred to the posterior knee or over the medial or lateral inferior patella
Symptoms may begin after a trauma or after repetitive physical activity, such as running and jumping
When maltracking, palpable and sometimes audible crepitus can occur
Intra-articular swelling usually does not occur unless there are articular cartilage defects or unless osteoarthritis develops
On physical examination, it is important to palpate the articular surfaces of the patella
Patellar mobility can be assessed by medially and laterally deviating the patella
- Deviation by one-quarter of the diameter of the kneecap is consider normal
- Deviation by greater than one-half of the diameter suggests excessive mobility

Diagnosis

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Imaging

Radiographs may show lateral deviation or tilting of the patella in relation to the femoral groove
MRI may show thinning of the articular cartilage but is not clinically necessary, except prior to surgery or to exclude other pathology

Diagnostic Studies

Apprehension sign
- Suggests instability of the patellofemoral joint
- Positive when the patient becomes apprehensive when the patella is deviated laterally (Table 41–7)
Patellar grind test
- Performed by grasping the knee superior to the patella and pushing it downward with the patient supine and the knee extended, pushing the patella inferiorly
- The patient is asked to contract the quadriceps muscle to oppose this downward translation, with reproduction of pain or grinding being considered a positive sign for chondromalacia of the patella

Table 41–7.Knee examination.

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Table 41–7. Knee examination.

Maneuver

Description

Inspection

Examine for the alignment of the lower extremities (varus, valgus, knee recurvatum), ankle eversion and foot pronation, gait, SEADS.

Palpation

Include important landmarks: patellofemoral joint, medial and lateral joint lines (especially posterior aspects), pes anserine bursa, distal iliotibial band and Gerdy tubercle (iliotibial band insertion).

Range of motion testing

Check range of motion actively (patient performs) and passively (clinician performs), especially with flexion and extension of the knee normally 0–10 degrees of extension and 120–150 degrees of flexion.

Knee strength testing

Test resisted knee extension and knee flexion strength manually.

Ligament Stress Testing

Lachman test

Performed with the patient lying supine, and the knee flexed to 20–30 degrees. The examiner grasps the distal femur from the lateral side, and the proximal tibia with the other hand on the medial side. With the knee in neutral position, stabilize the femur, and pull the tibia anteriorly using a similar force to lifting a 10- to 15-pound weight. Excessive anterior translation of the tibia compared with the other side indicates injury to the anterior cruciate ligament.

Anterior drawer

Performed with the patient lying supine and the knee flexed to 90 degrees. The clinician stabilizes the patient’s foot by sitting on it and grasps the proximal tibia with both hands around the calf and pulls anteriorly. A positive test finds anterior cruciate ligament laxity compared with the unaffected side.

Pivot shift

Used to determine the amount of rotational laxity of the knee. The patient is examined while lying supine with the knee in full extension. It is then slowly flexed while applying internal rotation and a valgus stress. The clinician feels for a subluxation at 20–40 degrees of knee flexion. The patient must remain very relaxed to have a positive test.

Valgus stress

Performed with the patient supine. The clinician should stand on the outside of the patient’s knee. With one hand, the clinician should hold the ankle while the other hand is supporting the leg at the level of the knee joint. A valgus stress is applied at the ankle to determine pain and laxity of the medial collateral ligament. The test should be performed at both 30 degrees and 0 degrees of knee extension.

Varus stress

The patient is again placed supine. For the right knee, the clinician should be standing on the right side of the patient. The left hand of the examiner should be holding the ankle while the right hand is supporting the lateral thigh. A varus stress is applied at the ankle to determine pain and laxity of the lateral collateral ligament. The test should be performed at both 30 degrees and 0 degrees of knee flexion.

Meniscal Signs

McMurray test

Performed with the patient lying supine. The clinician flexes the knee until the patient reports pain. For this test to be valid, it must be flexed pain-free beyond 90 degrees. The clinician externally rotates the patient’s foot and then extends the knee while palpating the medial knee for “click” in the medial compartment of the knee or pain reproducing pain from a meniscus injury. To test the lateral meniscus, the same maneuver is repeated while rotating the foot internally (53% sensitivity and 59–97% specificity).

Modified McMurray

Performed with the hip flexed to 90 degrees. The knee is then flexed maximally with internal or external rotation of the lower leg. The knee can then be rotated with the lower leg in internal or external rotation to capture the torn meniscus underneath the condyles. A positive test is pain over the joint line while the knee is being flexed and internally or externally rotated.

Thessaly test

Performed with the patient standing on one leg with knee slightly flexed. The patient is asked to twist the knee while standing on one leg. Pain can be elicited during twisting motion.

SEADS, swelling, erythema, atrophy, deformity, and (surgical) scars.

Treatment

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Surgery

Considered a last resort for patellofemoral pain
Procedures performed include lateral release or patellar realignment surgery

Therapeutic Procedures

For symptomatic relief, ice and anti-inflammatory medications can be beneficial
Strengthening exercises should include the quadriceps and hip abductors; posterolateral hip muscle strengthening is better than a quadriceps strengthening program in reducing symptoms of patellofemoral pain
A patellar stabilizer brace or special taping techniques (McConnell taping)
Correcting lower extremity alignment (with appropriate footwear or over-the-counter orthotics) can help improve symptoms
If the patient demonstrates tight peripatellar soft tissues, stretching the hamstrings, iliotibial band, quadriceps, calves and hip flexors may be helpful

Outcome

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When to Refer

Patients with persistent symptoms despite a course of conservative therapy

References

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Bolgla LA et al. National Athletic Trainers' Association Position Statement: management of individuals with patellofemoral pain. J Athl Train. 2018 Sep;53(9):820–36.
[PubMed: 30372640]

Crossley KM et al. Rethinking patellofemoral pain: prevention, management and long-term consequences. Best Pract Res Clin Rheumatol. 2019 Feb;33(1):48–65.
[PubMed: 31431275]

Jin J et al. JAMA patient page. Patellofemoral pain. JAMA. 2018 Jan 23;319(4):418.
[PubMed: 29362797]

Neal BS et al. Risk factors for patellofemoral pain: a systematic review and meta-analysis. Br J Sports Med. 2019 Mar;53(5):270–81.
[PubMed: 30242107]

Purohit N et al. Surgical management of patellofemoral instability. I. Imaging considerations. Skeletal Radiol. 2019 Jun;48(6):859–69.
[PubMed: 30542758]

Saltychev M et al. Effectiveness of conservative treatment for patellofemoral pain syndrome: a systematic review and meta-analysis. J Rehabil Med. 2018 May 8;50(5):393–401.
[PubMed: 29392329]

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Key Features

Essentials of Diagnosis

General Considerations

Clinical Findings

Symptoms and Signs

Diagnosis

Imaging

Diagnostic Studies

Treatment

Surgery

Therapeutic Procedures

Outcome

When to Refer

References

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