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Stress View Knee

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Other Names

  • Valgus stress view
  • Varus stress view
  • Posterior stress view
  • PCL stress view
  • MCL stress view

Introduction

Stress View Kneeling
  • Can be used for many reasons during workup and recovery for potential ligamentous injury or osteoarthritis
  • Most common include varus stress, valgus stress and posterior stress views
  • Manual stress usually provided by healthcare professional
    • Many times the ordering physician
  • May need patient directed stresses or props to complete

Standard Views

Stress Views Lateral
  • The standard views of the knee most often include anteroposterior, or AP, which can be weight-bearing or non weight-bearing
  • Lateral view
  • Merchant or sunrise

Pathology

Medial knee injury

  • MCL Injury: Most commonly injured area of knee is the medial collateral ligament
      • Proximal and deep portion of superficial MCL or the meniscofemoral and meniscotibial vision of the deep MCL
      • Capsular arm of the posterior oblique ligament
    • Stress radiographs can judge degree of instability with the measurement of medial compartment gapping
    • Valgus stress views are normally compared to unaffected knee
      • Has been shown to have minimal side to side difference in healthy patients [1]
    • Value for involvement of superficial medial collateral ligament was 3.2 mm or greater at 20 degrees flexion
    • Value for involvement of most or all medial knee structures was found to be 9.8 mm when stress done at 20 degrees flexion [2]

Lateral knee injury

  • LCL Injury: Used in similar nature for lateral knee injuries for varus stress radiographs
      • More variability among lateral gapping compared to medial side [3]
      • Main lateral stabilizers to the posterolateral knee are the fibular collateral ligament, the popliteus tendon and the popliteofibular ligament
    • Complete fibular collateral ligament tear demonstrated 2.7 to 3.9 mm
    • Increase in 4.0 mm or greater felt to indicate injury to three main static stabilizers

Posterior stress injury

  • PCL Injury: Posterior cruciate ligament injuries occur mostly in athletic population
      • PCL has two bundles, the anterolateral an posteromedial bundle
      • Lies between the anterior meniscofemoral ligament (ligament of Humphrey) and posterior meniscofemoral ligament (ligament of Wrisberg)
  • Grading of PCL injuries can be very difficult on physical examination and stress views can be used
    • Shown to be superior to clinical or arthrometer evaluation [4]
    • For kneeling stress views, patient kneels on a jig or radiopaque pad with knee at 90 degrees flexion
      • Pad or bench supports lower leg up to tibial tubercle and the patella and femoral condyles are unsupported
      • Important to ask patient to place their weight down and relax while radiographs are being done
    • To perform measurements, first a line was traced across the tibial plateau, then two perpendicular lines were traced passing through the midpoint between the most posterior edges of the medial and lateral condyles and the tibial plateau, respectively, parallel to the posterior tibial cortex.
    • Then, the degree of posterior tibial displacement (PTD) is measured as the distance in mm between the two lines
    • Diagnostic algorithm has been validated where:
      • 0–7 mm of side-to-side difference in posterior displacement constitutes a partial PCL tear
      • 8–11 mm constitutes an isolated complete constitutes a combined PCL and posterolateral corner or posteromedial corner knee injury [5]
    • Lateral stress views can be used and compared to unaffected side with knee flexed at 70 degrees
      • More similar to varus and valgus views with manual stress being applied
    • Asymmetric posterior tibial displacement >12 mm on stress views suggests a combined PCL and PLC injury

Osteoarthritis

  • See: Osteoarthritis of the Knee
  • Valgus stress can be used for workup of varus osteoarthritis in attempts to quantify cartilage thickness
    • Shown to predict cartilage thickness, but not damage [6]
  • Used in pre-operative planning of soft tissue balancing during TKA and evaluation of medial knee stability during the postoperative period
  • Varus stress radiographs used for planning of unicompartmental knee arthroplasty or measuring knee stabilizers after total knee arthroplasty

See Also


References

  1. Jacobsen K. Stress radiographical measurements of post-traumatic knee instability. Acta Orthop Scand. 1977;48:301-310.
  2. Coobs BR, Wijdicks CA, Armitage BM, Spiridonov SI, Westerhaus BD, Johansen S, Engebretsen L, LaPrade RF. An in vitro analysis of an anatomical medial knee reconstruction. Am J Sports Med. 2010;38:339-47
  3. Coobs BR, LaPrade RF, Griffith CJ, Nelson BJ. Biomechanical analysis of an isolated fibular (lateral) collateral ligament reconstruction using an autogenous semitendinosus graft. Am J Sports Med. 2007;35:1521-7.
  4. Schulz MS, Russe K, Lampakis G, Strobel MJ. Reliability of stress radiography for evaluation of posterior knee laxity. Am J Sports Med 2005;4:502–6
  5. Jackman T, LaPrade RF, Pontinen T, Lender PA. Intraobserver and interobserver reliability of the kneeling technique of stress radiography for the evaluation of posterior knee laxity. Am J Sports Med. 2008; 36(8):1571–6
  6. Waldstein, Wenzel et al. Valgus Stress Radiographs Predict Lateral-Compartment Cartilage Thickness but Not Cartilage Degeneration in Varus Osteoarthritis. The Journal of Arthroplasty, Volume 32, Issue 3, 788 - 792.
Created by:
John Kiel on 30 December 2019 14:27:41
Last edited:
14 February 2020 14:53:03
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