Pellegrini–Stieda syndrome

Overview

Pellegrini–Stieda syndrome is a condition characterized by the calcification or ossification of the medial collateral ligament (MCL) of the knee, particularly at its femoral attachment. This abnormal calcification is usually the result of previous trauma or injury to the MCL and may be asymptomatic or associated with chronic medial knee pain and stiffness. The syndrome is named after the radiologists Augusto Pellegrini and Alfred Stieda, who independently described the radiographic findings of MCL calcification in the early 20th century. Although often detected incidentally on X-rays, the syndrome may occasionally cause significant clinical symptoms, especially in active individuals or those with unresolved ligamentous injuries.

Causes

The primary cause of Pellegrini–Stieda syndrome is trauma to the medial collateral ligament, typically from sports injuries, direct blows to the lateral side of the knee, or valgus stress that stretches or tears the ligament. The injury leads to inflammation and possible microhemorrhage at the ligament’s femoral origin, which over time may undergo dystrophic calcification or ossification. Other contributing factors include:

• Chronic mechanical stress: Repetitive strain or overuse of the knee joint

• Incomplete healing: Poor recovery from prior MCL sprains or tears

• Post-surgical changes: Calcification may occur as a sequela to knee surgeries involving the medial compartment

• Idiopathic origins: In rare cases, calcification occurs without an identifiable injury or trauma

Symptoms

While many individuals with Pellegrini–Stieda syndrome are asymptomatic and diagnosed incidentally during imaging for unrelated issues, others may experience noticeable symptoms. These may include:

• Medial knee pain: Often chronic and dull, located near the femoral origin of the MCL

• Swelling or tenderness: Particularly along the inner aspect of the knee

• Limited range of motion: Stiffness, especially during extension or after periods of inactivity

• Mechanical symptoms: A catching or grinding sensation due to the calcified tissue

• Increased pain during activity: Especially in sports involving pivoting, running, or lateral movements

In some cases, the pain may mimic other intra-articular knee pathologies, requiring a careful clinical evaluation to differentiate.

Diagnosis

Diagnosis of Pellegrini–Stieda syndrome is based on clinical examination and confirmatory imaging studies. The process typically involves:

• Patient history: Inquiry about past knee injuries, surgeries, or persistent medial knee discomfort

• Physical examination: Palpation for tenderness over the MCL, assessment of knee stability, and range of motion

• X-ray imaging: The key diagnostic tool, which shows linear or oval calcification near the femoral origin of the MCL

• MRI (Magnetic Resonance Imaging): Helpful in evaluating the integrity of the MCL, identifying concurrent injuries (e.g., meniscus tears), and ruling out other causes of knee pain

• Ultrasound: May be used for dynamic evaluation and to assess soft tissue involvement

The radiographic appearance of Pellegrini–Stieda calcification is typically seen as a crescent- or spindle-shaped opacity adjacent to the medial femoral condyle.

Treatment

Treatment of Pellegrini–Stieda syndrome depends on the severity of symptoms. Many cases require no intervention if asymptomatic. For symptomatic patients, treatment options include:

Conservative Management:

• Rest and activity modification: To avoid activities that exacerbate symptoms

• Nonsteroidal anti-inflammatory drugs (NSAIDs): For pain relief and reduction of inflammation

• Physical therapy: To improve knee strength, flexibility, and support MCL healing

• Bracing: A knee brace may provide additional support and help offload stress on the medial structures

• Corticosteroid injections: May be considered in some cases to reduce inflammation and pain

Surgical Management:

• Excision of calcified tissue: Surgical removal of the ossified area may be necessary in cases of persistent pain or mechanical interference

• MCL reconstruction or repair: In cases of concurrent ligament instability or structural damage

Surgery is usually reserved for individuals who fail conservative management or have significant functional impairment.

Prognosis

The prognosis for Pellegrini–Stieda syndrome is generally good, particularly for individuals with mild or no symptoms. Most patients respond well to conservative treatment and can return to normal activities with appropriate care. For those requiring surgery, outcomes are typically favorable, especially when performed by experienced orthopedic surgeons. However, if left untreated in symptomatic cases, the condition can lead to chronic knee discomfort and limited joint function. Early diagnosis, individualized treatment, and adherence to physical therapy are key to achieving optimal recovery and preventing complications.