Quadriceps Tendon Anatomy

Background

Definition: Rupture of the tendon attaching the quadriceps muscles to the patella

Anatomy

  • The quadriceps muscle is divided into four muscle bellies: vastus medialis, vastus intermedius, vastus lateralis and rectus femoris
  • These join together into a single confluence which inserts onto the patella, known as the quadriceps tendon

Epidemiology (Uptodate, Wheeless)

  • Location
    • Tears usually occur just above the insertion on the patella
    • Tears occur twice as often in nondominant leg
  • Less common injury than patellar tendon tear
  • M:F ratio of 8:1
  • Risk factors include: advanced age, anabolic steroid use, renal failure, diabetes, rheumatoid arthritis, hyperparathyroidism, connective tissue disorders, steroid use, intraarticular injections

Presentation (Wheeless)

  • Mechanism
    • Eccentric loading of the leg while slightly bent, such as a change of direction while running or landing from a jump
    • May also occur with a direct blow, particularly in younger patients
    • Patients often report a “pop” or tearing sensation
  • Patients may complain knee pain, swelling, and difficulty walking

  • Quadriceps Tendon Rupture Physical Exam (eorif.com)

    Physical Exam

    • Tenderness superior to patella at site of rupture
    • Palpable defect superior to the patella
    • Swelling of the knee
    • Inability to extend the knee against resistance or inability to straight leg raise
      • This may be preserved in partial tears

Patella Baja Lateral XRay (orthobullets.com)

Imaging

  • Plain X-rays
    • Necessary Views: AP and lateral
      • Patella baja
        • Patella located lower in relation to knee than normal
        • Will see in complete tear as patellar tendon displaces patella distally
      • May reveal associated patellar fracture
  • Ultrasound can effectively be used to identify quadriceps tendon tears (Pasta)
    • Accuracy is operator dependent
    • Diagnosed by visualization of ruptured tendon and hematoma

Quadriceps Tendon Rupture Ultrasound (theultrasoundsite.co.uk)

  • MRI
    • Gold standard to determine whether a tear is partial or complete
    • Can determine presence of injury if physical exam, ultrasound, and X-ray inconclusive
    • Rarely, if ever, necessary in the ED

Quadriceps Tendon Rupture MRI (Case courtesy of Dr Chris O’Donnell, Radiopaedia.org. From the case rID: 43540)

ED Management

  • Provide analgesia
  • Place knee immobilizer and provide crutches
    • Knee immobilization crucial for partial tears
    • If patient allowed to bear weight on flexed leg, partial tear may progress to complete tear and become operative
  • Patients with isolated quadriceps rupture may be discharged from the ED with supportive care measures (rest, ice, elevation, analgesia)
    • Emergency orthopedics consultation typically not necessary
    • Close follow up with orthopedics (within 1 week) is appropriate as operative management indicated for all complete tears

Prognosis (Wheeless)

  • Non-operative management
    • Preferred for partial tears so long as the knee extensor mechanism is preserved
    • Generally 4-6 weeks of immobilization is recommended with gradual advancement of activities.
  • Operative management
    • Preferred for complete tears, and for partial tears where the extensor mechanism is not preserved
    • Outcomes are much improved if surgery is performed within 1 week
    • Surgery performed greater than 2 weeks after injury may result in significant contracture and shortening of the quadriceps tendon, making surgery more difficult and outcomes more poor
  • Patients will likely suffer decreased range of motion, decreased extensor strength, and have increased risk of repeat injury
    • It is uncommon that patients will be able to return to their former level of activity
  • Failed repair, missed concomitant injuries, and infection are the most common complications of surgical repair

Take Home Points

  • Missed quadriceps tendon tears can result in significant morbidity. Knee pain with limited ability to extend at the knee or straight leg raise should increase suspicion for this injury
  • Quadriceps tendon rupture may result from direct trauma or from axial loading of slightly flexed leg while running or jumping
  • For suspected quadriceps tendon rupture, knee X-rays should be obtained to evaluate for patellar fracture. Non-emergent MRI may be needed to differentiate between complete and partial tendon tears
  • Patients may be discharged from the ED but will need close follow-up with an orthopedic surgeon to allow for timely surgical repair

Read More:

Orthobullets: Quadriceps Tendon Rupture

Wheeless’ Textbook of Orthopaedics: Rupture of the Quadriceps

References

Bianchi S et al. Ultrasound appearance of tendon tears. Part 2: lower extremity and myotendinous tears. Skeletal Radiol. 2006 Feb;35(2):63-77. PMD: 16382328

McKean J. Quadriceps Tendon Injuries. Link

Pasta G. Sonography of the quadriceps muscle: Examination technique, normal anatomy, and traumatic lesions. J Ultrasound. 2010 Jun; 13(2): 76–84. PMD: 23396806

Perfitt JS et al. Acute quadriceps tendon rupture: a pragmatic approach to diagnostic imaging. Eur J Orthop Surg Traumatol. 2014 Oct;24(7):1237-41. PMD: 23996080

Wheeless CR. Wheeless’ Textbook of Orthopaedics: Rupture of the Quadriceps.  Link