Hughston's Plica Test: Understanding, Procedure, and Clinical Significance

What is Hughston's Plica Test?

Hughston's Plica Test is a specific orthopedic assessment used by healthcare professionals to evaluate for the presence of symptomatic medial patellar plica syndrome, a condition characterized by irritation or inflammation of a remnant synovial fold within the knee joint.

Understanding Plica Syndrome

The knee joint, a complex articulation of bone, cartilage, ligaments, and muscle, also contains various synovial folds or "plicas" – remnants of embryonic development. While several plicas exist, the medial patellar plica is the most commonly implicated in symptomatic conditions. Normally, these folds are soft, pliable, and asymptomatic.

Plica Syndrome occurs when a plica becomes irritated, inflamed, or thickened. This can be due to:

• Acute Trauma: A direct blow to the knee.
• Repetitive Stress: Overuse activities involving knee flexion and extension, such as running, cycling, or squatting.
• Anatomical Variation: A particularly large or rigid plica that impinges between the patella and the medial femoral condyle.

When symptomatic, a plica can cause a range of issues including anterior knee pain (often on the medial side), clicking, popping, snapping sensations, and sometimes a feeling of catching or pseudo-locking.

Purpose of Hughston's Plica Test

Hughston's Plica Test is a clinical provocation test designed to reproduce the symptoms associated with an irritated medial patellar plica. Its primary purpose is to help clinicians differentiate plica syndrome from other conditions that cause similar anterior knee pain, such as patellofemoral pain syndrome, meniscal tears, or chondromalacia patellae. By specifically stressing the medial plica, the test aims to elicit a characteristic pain response or mechanical sensation.

How Hughston's Plica Test is Performed

The test is typically performed by a trained clinician (e.g., physician, physical therapist, athletic trainer). Here's a step-by-step breakdown:

1. Patient Positioning: The patient lies supine (on their back) on an examination table. The affected knee is flexed to approximately 90 degrees, allowing for full range of motion during the test.
2. Examiner's Hand Placement:
   • The examiner grasps the patient's ankle or lower leg with one hand to control the knee's flexion and extension.
   • With the other hand, the examiner applies a medial glide (pushing the kneecap towards the inside of the thigh) to the patella.
   • Simultaneously, the examiner internally rotates the tibia (twisting the lower leg inward). This combination of actions aims to tension and bring the medial patellar plica into contact with the medial femoral condyle.
3. Execution of the Test: While maintaining the medial glide of the patella and internal rotation of the tibia, the examiner slowly and passively extends the patient's knee from 90 degrees of flexion to full extension. The focus is particularly on the range of motion between approximately 30 and 60 degrees of knee flexion, as this is where the plica is most likely to impinge.

Interpreting the Results

The interpretation of Hughston's Plica Test focuses on the patient's response during the maneuver:

• Positive Test: A positive test is indicated by the reproduction of the patient's familiar anterior knee pain, particularly on the medial side, during the extension phase. Often, a palpable or audible clicking, snapping, or popping sensation may also be noted by the examiner or felt by the patient as the plica passes over the medial femoral condyle. The pain or sensation typically occurs between 30 and 60 degrees of knee flexion.
• Negative Test: If the patient experiences no pain, clicking, or other symptoms during the maneuver, the test is considered negative for symptomatic plica syndrome.

It's crucial to note that a positive test indicates the presence of symptomatic plica, but it does not rule out other co-existing knee pathologies.

Clinical Significance and Limitations

Hughston's Plica Test is a valuable tool in the differential diagnosis of anterior knee pain, but it should never be used in isolation.

Clinical Significance:

• Supports Diagnosis: A positive Hughston's test, when combined with a thorough patient history (e.g., pain with repetitive knee flexion/extension, clicking/snapping sensations) and other clinical findings, strengthens the suspicion of medial patellar plica syndrome.
• Guides Treatment: If plica syndrome is suspected, conservative management (rest, anti-inflammatory medication, physical therapy focusing on quadriceps strengthening, stretching, and activity modification) is often the first line of treatment. In refractory cases, surgical intervention (arthroscopic plica excision) may be considered.

Limitations:

• Sensitivity and Specificity: Like many orthopedic special tests, Hughston's test has varying reported sensitivity and specificity. This means it can sometimes yield false positives (a positive test when no plica pathology exists) or false negatives (a negative test despite a symptomatic plica).
• Subjectivity: The interpretation relies on the patient's subjective report of pain and the examiner's ability to feel subtle mechanical phenomena.
• Differential Diagnosis: Many conditions can mimic plica syndrome symptoms. Therefore, a comprehensive examination including other orthopedic tests (e.g., patellar apprehension test, meniscus tests), palpation, range of motion assessment, and sometimes imaging (MRI, though plicas are often normal findings on MRI) is essential for an accurate diagnosis.

When to Seek Professional Guidance

If you are experiencing persistent anterior knee pain, especially with clicking, snapping, or catching sensations, it is imperative to consult a healthcare professional. An accurate diagnosis is crucial for effective management. A physical therapist, sports medicine physician, or orthopedic surgeon can perform Hughston's Plica Test and other necessary assessments to determine the underlying cause of your knee pain and recommend the most appropriate course of action. Self-diagnosis and treatment are not recommended for complex joint issues.