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PCL Injury

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Topic updated on 07/15/15 7:23pm
Introduction
  • Injuries may be isolated or combined and often go undiagnosed in the acutely injured knee
  • Epidemiology
    • incidence
      • 5-20% of all knee ligamentous injuries
  • Pathophysiology
    • mechanism
      • direct blow to proximal tibia with a flexed knee (dashboard injury)
      • noncontact hyperflexion with a plantar-flexed foot
      • hyperextension injury
    • pathoanatomy
      • PCL is the primary restraint to posterior tibial translation
      • functions to prevent hyperflexion/sliding
      • isolated injuries cause the greatest instability at 90° of flexion
  • Associated conditions
    • combined PCL and posterolateral corner (PLC) injuries
    • multiligamentous knee injuries
    • knee dislocation 
  • Prognosis
    • chronic PCL deficiency
      • PCL deficiency leads to increased contact pressures in the patellofemoral and medial compartments of the knee due to varus alignment 
      • controversial whether late patellar and MFC chondrosis will develop
Anatomy
  • PCL anatomy  
    • origin
      • posterior tibial sulcus below the articular surface  
    • insertion
      • anterolateral medial femoral condyle  
      • broad, crescent-shaped footprint
    • dimensions
      • 38 mm in length x 13 mm in diameter
      • PCL is 30% larger than the ACL
    •  PCL has two bundles  
      • anterolateral bundle
        • tight in flexion
        • strongest and most important for posterior stability at 90° of flexion
        • mnemonic "PAL" - PCL has  an AnteroLateral bundle
      • posteromedial bundle
        • tight in extension
        • reciprocal function to the anterolateral bundle 
    • lies between the meniscofemoral ligaments  
      • ligament of Humphrey (anterior) and ligament of Wrisberg (posterior)
        • originate from the posterior horn of the lateral meniscus and insert into PCL substance
  • Blood supply
    • supplied by branches of the middle geniculate artery and fat pad
  • Biomechanics
    • strength is 2500 to 3000 N (posterior)
    • minimizes posterior tibial displacement (95%)
Classification
  • Classification based on posterior subluxation of tibia relative to femoral condyles (with knee in 90° of flexion)
    • Grade I (partial)
      • 1-5 mm posterior tibial translation
      • tibia remains anterior to the femoral condyles
    • Grade II (complete isolated)
      • 6-10 mm posterior tibial translation
      • complete injury in which the anterior tibia is flush with the femoral condyles
    • Grade III (combined PCL and capsuloligamentous)
      • >10 mm posterior tibial translation
      • tibia is posterior to the femoral condyles and often indicates an associated ACL and/or PLC injury
Presentation
  • History
    • differentiate between high- and low-energy trauma
      • dashboard injury
      • hyperflexion athletic injury with a plantar-flexed foot
    • ascertain a history of dislocation or neurologic injury
  • Symptoms
    • posterior knee pain
    • instability
      • often subtle or asymptomatic in isolated PCL injuries
  • Physical exam
    • varus/valgus stress
      • laxity at indicates MCL/LCL and PCL injury
      • laxity at 30° alone indicates MCL/LCL injury
    • posterior sag sign
      • patient lies supine with hips and knees flexed to 90°, examiner supports ankles and observes for a posterior shift of the tibia as compared to the uninvolved knee 
      • the medial tibial plateau of a normal knee at rest is 10 mm anterior to the medial femoral condyle
        • an absent or posteriorly-directed tibial step-off indicates a positive sign
    • posterior drawer test (at 90° flexion) post
      • with the knee at 90° of flexion, a posteriorly-directed force is applied to the proximal tibia and posterior tibial translation is quantified 
        • isolated PCL injuries translate >10-12 mm in neutral rotation and 6-8 mm in internal rotation
        • combined ligamentous injuries translate >15 mm in neutral rotation and >10 mm in internal rotation
      • most accurate maneuver for diagnosing PCL injury
    • quadriceps active test post
      • attempt to extend a knee flexed at 90° to elicit quadriceps contraction
      • positive if anterior reduction of the tibia occurs relative to the femur
    • dial test  
      • > 10° ER asymmetry at 30° & 90° consistent with PLC and PCL injury
      • > 10° ER asymmetry at 30° only consistent with isolated PLC injury
    • KT-1000 and KT-2000 knee ligament arthrometers
      • used for standardized laxity measurement although less accurate than for ACL
Imaging
  • Radiographs
    • recommended views
      • AP and supine lateral
        • may see avulsion fractures with acute injuries
        • assess for posterior tibiofemoral subluxation
        • medial and patellofemoral compartment arthrosis may be present with chronic injuries
      • lateral stress view  
        • apply stress to anterior tibia with the knee flexed to 70°
        • asymmetric posterior tibial displacement indicates PCL injury
        • contralateral knee differences >12 mm on stress views suggest a combined PCL and PLC injury
        • becoming the gold standard in diagnosing and quantifying PCL injuries
      • kneeling stress radiographs of knee
  • MRI  
    • confirmatory study for the diagnosis of PCL injury
Treatment
  • Nonoperative
    • protected weight bearing & rehab
      • indications
        • isolated Grade I (partial) and II (complete isolated) injuries
      • modalities
        • quadriceps rehabilitation with a focus on knee extensor strengthening  
      • outcomes
        • return to sports in 2-4 weeks
    • relative immobilization in extension for 4 weeks
      • indications
        • isolated Grade III injuries
        • surgery may be indicated with bony avulsions or a young athlete
      • modalities
        • extension bracing with limited daily ROM exercises
        • immobilization is followed by quadriceps strengthening
  • Operative
    • PCL repair of bony avulsion fractures or reconstruction
      • indications
        • combined ligamentous injuries 
          • PCL + ACL or PLC injuries
          • PCL + Grade III MCL or LCL injuries
        • isolated Grade II or III injuries with bony avulsion
        • isolated chronic PCL injuries with a functionally unstable knee
      • techniques
        • primary repair of bony avulsion fractures with ORIF
        • reconstruction options include
          • tibial inlay vs. transtibial methods
          • single-bundle vs. double-bundle
          • autograft vs. allograft
        • allograft is typically utilized with multiple graft choices available
          • options include - Achilles, bone-patellar tendon-bone, hamstring, and anterior tibialis
      • outcomes
        • good results achieved with primary repair of bony avulsions
        • primary repair of midsubstance ruptures are typically not successful
        • results of PCL reconstruction are less successful than with ACL reconstruction and residual posterior laxity often exists
        • successful reconstruction depends on addressing concomitant ligament injuries
        • no outcome studies clearly support one reconstruction technique over the other
    • high tibial osteotomy
      • indications
        • chronic PCL deficiency
      • techniques
        • consider medial opening wedge osteotomy to treat both varus malalignment and PCL deficiency 
        • when performing a high tibial osteotomy in a PCL deficient knee, increasing the tibial slope helps reduce the posterior sag of the tibia 
Surgical Techniques
  • Arthroscopic transtibial technique 
    • approach
      • standard arthroscopic portals with an accessory posteromedial portal
        • posteromedial portal is placed 1 cm proximal to the joint line posterior to the MCL
        • avoid injury to branches of the saphenous nerve during placement
      • posteromedial corner of the knee is best visualized with a 70° arthroscope either through the notch (modified Gillquist view) or using a posteromedial portal
    • technique
      • transtibial drilling anterior to posterior
      • fix graft in flexion 
    • pros & cons
      • risk to popliteal vessels
  • Open (tibial inlay)
    • approach
      • uses a posteromedial incision between medial head of gastrocnemius and semimembranosus 
    • technique
      • used for ORIF of bony avulsion
    • pros & cons
      • biomechanical advantage with a decrease in the "killer turn" with less graft attenuation and failure
      • screw fixation of the graft bone block is within 20 mm of the popliteal artery
  • Single-bundle technique
    • approach
      • arthroscopic or open
    • technique
      • reconstruct the anterolateral bundle
      • tension at 90° of flexion
  • Double-bundle technique
    • approach
      • arthroscopic or open techniques may be utilized
    • technique
      • anterolateral bundle tensioned in 90° of flexion
      • posteromedial bundle tensioned in extension
    • pros & cons
      • biomechanical advantage with knee function in flexion and extension
      • clinical advantage has yet to be determined
      • may be advantageous to perform with combined PCL/PLC injuries for better rotational control as PLC reconstructions typically loosen over time
Rehabilitation
  • Postoperative care 
    • immobilize in extension early and protect against gravity
    • early motion should be in prone position
  • Rehabilitation
    • focus on quadriceps rehabilitation  
    • avoid resisted hamstring strengthening exercises (ex. hamstring curls) in early rehab
      • this is because the hamstrings create a posterior pull on the tibia which increases stress on the graft.
Complications
  • Popliteal artery injury   
    • at risk when drilling the tibial tunnel
    • lies just posterior to PCL insertion on the tibia, separated only by posterior capsule
  • Patellofemoral pain/arthritis
    • due to chronic PCL deficiency

 

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Qbank (8 Questions)

TAG
(OBQ11.204) Which of the following should be avoided in early rehabilitation following posterior cruciate ligament (PCL) reconstruction? Topic Review Topic

1. Quadriceps muscle activation
2. Closed chain active terminal extension exercises
3. Prone passive flexion with active terminal extension
4. Prone hamstring curls
5. Active maximal ankle dosiflexion

PREFERRED RESPONSE ▶
TAG
(OBQ09.35) A 23-year-old collegiate soccer player sustained a right knee injury 6 months ago. He has been treated with rest and rehabilitation but is unable to play at his previous level due to his knee "giving way." Physical exam reveals 10° varus alignment when standing and a varus thrust with walking. Strength is full compared to the other side. Ligamentous exam reveals a stable ACL and MCL, but opens to a varus stress and a 3+ posterior drawer and positive dial test at both 30° and 90° degrees of flexion. What is the best treatment option to allow this patient to return to competitive athletic activity? Topic Review Topic

1. Functional bracing
2. Reconstruction of the PCL
3. Reconstruction of the ACL and PCL
4. High tibial osteotomy to decrease tibial slope and correct varus malalignment; reconstruction of the PCL & PLC
5. High tibial osteotomy to increase tibial slope and correct varus malalignment; reconstruction of the PCL & PLC

PREFERRED RESPONSE ▶
TAG
(OBQ09.82) Which of the following rehabilitation principles is true regarding non-operative treatment of a grade II PCL tear? Topic Review Topic

1. Quadriceps strengthening and prone range of motion should begin as tolerated
2. Hamstring strengthening and supine range of motion should begin as tolerated
3. Resisted quadriceps and hamstring strengthening, no early range of motion
4. No strengthening for 6 weeks
5. No range of motion for 6 weeks

PREFERRED RESPONSE ▶
TAG
(OBQ07.4) At what angle of knee flexion should the graft be tensioned at during posterior cruciate ligament (PCL) reconstruction with a single bundle graft? Topic Review Topic

1. 5 degrees hyperextension
2. 0 degrees flexion
3. 15 degrees flexion
4. 30 degrees flexion
5. 90 degrees flexion

PREFERRED RESPONSE ▶
TAG
(OBQ07.15) Figure A is an arthroscopic image of a left knee as viewed from an anterolateral viewing portal demonstrating the attachment footprint of a damaged structure. Strengthening of what muscle group most effectively counteracts the deficit that results from the damaged structure? Topic Review Topic
FIGURES: A          

1. Hip flexors
2. Hip abductors
3. Gastroc-soleus
4. Quadriceps
5. Hamstrings

PREFERRED RESPONSE ▶
TAG
(OBQ06.55) A football player sustains an isolated posterior cruciate ligament (PCL) tear. Which of the following mechanisms is most likely to have caused this injury? Topic Review Topic

1. Fall on the flexed knee with the foot in plantarflexion
2. Fall on the flexed knee with the foot in dorsiflexion
3. Non-contact twist causing knee external rotation and valgus
4. Non-contact twist causing knee internal rotation and varus
5. Direct contact blow to the posterior knee

PREFERRED RESPONSE ▶
TAG
(OBQ06.99) A 35-year-old construction worker presents with medial-sided knee pain. He has no instability complaints but at age 18, he sustained a Grade 1 PCL injury that was treated non-operatively. A radiograph is shown in Figure A. What surgical treatment is the best option given his age and occupation? Topic Review Topic
FIGURES: A          

1. PCL reconstruction
2. Unicompartmental knee replacement
3. Total knee replacement
4. Lateral closing wedge osteotomy of the proximal tibia
5. Medial opening wedge osteotomy of the proximal tibia

PREFERRED RESPONSE ▶
TAG
(OBQ04.161) A 35-year-old male sustained an isolated PCL injury over 5 years ago which was treated non-operatively. If his follow-up radiographs show degenerative changes related to his PCL-deficiency, the changes are likely to be present in which of the following knee compartments? Topic Review Topic

1. medial and patellofemoral
2. medial only
3. lateral
4. lateral and patellofemoral
5. patellofemoral only

PREFERRED RESPONSE ▶



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