Patellar tendon rupture

Background

• Occurs via forceful contraction of quadriceps muscle or falling on flexed knee
• Typically occur 2cm from insertion on patella

Patellar vs Quadriceps tendon rupture

Finding	Patellar tendon rupture	Quadriceps tendon rupture
Location	Distal to patella	Proximal to patella
Typical group	Patients <40yr with history of tendinitis or steroid injections	Patients >40yr
X-ray	Patella alta (high-riding patella)	Patella baja/infera (low-riding patella)

Clinical Features

• Sudden "pop" or tearing
• Diffuse swelling
• Defect may be palpable above or below the patella
• Partial tears lead to difficulty extending the knee
• Complete tears lead to absent straight leg raise while supine or extension of the knee again

Differential Diagnosis

Knee diagnoses

Acute knee injury

• Knee dislocation
• Knee fractures
  • Patella fracture
  • Segond fracture
  • Tibial plateau fracture
• Meniscus and ligament knee injuries
• Patella dislocation
• Patellar tendonitis
• Patellar tendon rupture
• Quadriceps tendon rupture

Nontraumatic/Subacute

• Arthritis
• Gout and Pseudogout
• Osgood-Schlatter disease
• Patellofemoral syndrome (Runner's Knee)
• Patellar tendonitis (Jumper's knee)
• Pes anserine bursitis
• Popliteal cyst (Bakers cyst)
• Prepatellar bursitis (nonseptic)
• Septic bursitis
• Septic joint
• DVT

Evaluation

• Ultrasound
  • Separation of the tendon can be visualized
• X-ray
  • Patella alta (or high-riding patella) is consistent with patella tendon rupture
  • Patella baja/infera (or low-riding patella) is consistent with quadriceps tendon rupture

Management

• Ortho consult in the ED
• Knee immobilizer, can be weight bearing
• Operative repair advised within 7 days

References

• Uptodate
• Wheeless' Textbook of Orthopaedics