What are the diagnostic criteria for quadriceps (quad) tendon tear?

From the Guidelines

The diagnostic criteria for a quadriceps tendon tear include a combination of clinical examination findings and imaging studies, with ultrasound being highly accurate in diagnosis, having sensitivity and specificity approaching 100%. Patients typically present with acute knee pain, inability to actively extend the knee, a palpable defect above the patella, and a high-riding patella on examination. The patient often reports a history of sudden knee pain during activities involving eccentric quadriceps contraction, such as descending stairs or landing from a jump. Physical examination reveals tenderness at the superior pole of the patella, a palpable gap in the quadriceps tendon, and inability to perform a straight leg raise or maintain an extended knee against gravity. Swelling and ecchymosis may be present. Some key points to consider in the diagnosis of quadriceps tendon tears include:

• Clinical presentation: acute knee pain, inability to extend the knee, palpable defect above the patella
• Imaging studies: ultrasound is highly accurate, with sensitivity and specificity approaching 100% 1
• Risk factors: age over 40, steroid use, diabetes, gout, renal failure, and previous knee injuries
• Importance of early diagnosis: complete tears typically require surgical repair within 2-3 weeks of injury to prevent retraction of the tendon and to achieve optimal functional outcomes. Ultrasound is a cost-effective alternative to MRI, and can accurately diagnose complete tears, making it a valuable tool in the diagnosis of quadriceps tendon tears 1.

From the Research

Diagnostic Criteria for Quad Tendon Tear

The diagnostic criteria for quad tendon tear involve a combination of clinical examination, radiography, and imaging modalities such as ultrasonography and magnetic resonance imaging (MRI).

• Clinical examination may be limited by patient factors such as obesity, renal failure, and steroid use, as well as patient cooperation 2.
• Radiography may be unremarkable, making it insufficient for diagnosis on its own 2, 3.

Imaging Modalities

• Ultrasonography:
  • Highly sensitive (1.0) but less specific (0.67) with a positive predictive value of 0.88 4.
  • Effective in identifying high-grade partial tears or complete ruptures, with a sensitivity and specificity of 100% in one study 5.
  • Can be used for bedside diagnosis in emergency settings 2, 3.
• Magnetic Resonance Imaging (MRI):
  • Displays a sensitivity of 1.0, a specificity of 1.0, and a positive predictive value of 1.0 4.
  • Recommended for use after clinical examination and radiography, either directly or as a supplementary test to ultrasonography to eliminate false positives 4.

Diagnostic Approach

• A proposed approach involves proceeding directly to MRI or initially assessing with ultrasound, followed by supplementary MRI for positive findings 4.
• The choice of imaging modality may depend on availability, patient factors, and clinical suspicion 4, 5, 2, 6, 3.