What are the symptoms of a quadriceps rupture?

Symptoms of Quadriceps Rupture

The classic triad of symptoms for quadriceps tendon rupture consists of acute pain, impaired knee extension, and a palpable suprapatellar gap. 1

Key Clinical Presentation

• Patients typically experience sudden, acute pain in the anterior thigh or knee region at the time of injury 1
• Inability to actively extend the knee or maintain an extended knee position against gravity is a hallmark finding 1, 2
• A palpable gap or defect above the patella (suprapatellar region) can be felt on examination 1, 3
• Patients are often unable to perform a straight leg raise test due to disruption of the extensor mechanism 4
• Many patients report a sensation of the knee "giving way" followed by collapse or inability to bear weight 2
• Swelling and ecchymosis in the anterior knee region typically develop shortly after injury 3

Mechanism of Injury

• Quadriceps ruptures commonly occur during activities that involve sudden eccentric contraction of the quadriceps, such as:
  • Descending stairs (common mechanism as seen in multiple case reports) 2
  • Fall with the knee in a flexed position 4
  • Sudden twisting movements of the leg 4

Risk Factors and Associated Conditions

• More common in individuals over 40 years of age 1
• Bilateral spontaneous ruptures may be associated with underlying medical conditions such as:
  • Gout 1
  • Diabetes 1
  • Steroid use (systemic or local injections) 1
• Can occur in healthy, active individuals, though this is less common 2

Diagnostic Pitfalls

• Quadriceps ruptures are frequently misdiagnosed initially, especially in cases of bilateral ruptures 3
• The diagnosis may be missed when there are concurrent injuries (such as fractures) that distract from the knee examination 4
• In the setting of a leg fracture with immobilization, the inability to extend the knee may be attributed to pain rather than tendon rupture 4
• Delayed diagnosis can lead to poorer outcomes, as early surgical repair (ideally within 48-72 hours) is generally recommended for complete ruptures 5

Imaging Findings

• MRI is the most accurate imaging modality for confirming the diagnosis, with superior sensitivity and specificity 6
• Ultrasound can be considered as an alternative but has limitations in accuracy, particularly for partial tears 6
• Plain radiographs should be obtained initially to rule out associated fractures or other bony abnormalities 6

Clinical Examination Tips

• Always test active knee extension and straight leg raise in patients with knee pain, even when other injuries are present 4
• Palpate carefully above the patella to identify any defect in the quadriceps tendon 1
• Compare with the contralateral knee to identify asymmetry 3
• Maintain a high index of suspicion in older patients or those with risk factors 1