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Posterior Cruciate Ligament (PCL) Tear

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Ovid: 5-Minute Sports Medicine Consult, The


Posterior Cruciate Ligament (PCL) Tear
Priscilla Tu
Basics
Description
Rupture of any or all parts of the posterior cruciate ligament (PCL) of the knee (anterolateral portion and posteromedial portion)
Epidemiology
Incidence
  • All knee injuries in general population 3%
  • Knee injuries in trauma patients 38%
  • Knee injuries in athletes <1%, although may be underreported and/or underdiagnosed
Risk Factors
  • Contact sports, especially American football
  • Other sports, specifically soccer, skiing, and wrestling
Commonly Associated Conditions
  • Anterior cruciate ligament (ACL) tear
  • Lateral or medial collateral ligament tears
  • Meniscal derangement
  • Posterolateral corner injury
  • Tibial plateau fractures
  • Bony avulsions at the insertions of the cruciate ligament
  • Avulsion fracture at the tibial tubercle
  • Fibular head fracture
  • Chondral injury
  • Posterior knee subluxation or dislocation caused by hamstring force in the PCL-deficient knee
Diagnosis
History
  • “Dashboard injury”: Traumatic injury, often seen in motor vehicle accidents, with posteriorly directed force to the anterior proximal tibia in a flexed knee
  • Similar mechanism to preceding in sports, particularly in American football and wrestling, with opponent's hit to lower leg driving tibia backwards and rupturing PCL
  • Often in sports, fall onto flexed knee, particularly with foot plantarflexed
  • Less commonly, cutting, twisting, and hyperextension injury in sports; often accompanied by other ligament injuries
Physical Exam
  • Mild to moderate pain in the knee
  • Rapid onset (within few hours) of swelling and tenderness in knee
  • May have difficulty walking or walk with slight limp
  • May experience feeling of instability in the knee
  • Pain with kneeling, squatting, twisting, or walking up or down stairs and inclines
  • Discomfort felt with flexion
  • Anterior patellar contusions may be seen.
  • Posterior knee or popliteal ecchymosis may be found.
  • Neurovascular examination:
    • Perform neurovascular examination before other provocative tests.
    • Important to determine and document associated nerve damage or vascular injury (particularly popliteal artery injury)
  • Comprehensive knee examination:
    • Rule out dislocation.
    • Rule out other ligament or meniscus injuries.
  • Posterior drawer test:
    • Perform with the patient supine and knee flexed at 90 degrees and hip flexed at 45 degrees
    • Examiner stabilizes foot.
    • A posteriorly directed force is applied to the proximal tibia to elicit abnormal posterior tibial translation.
    • Posterior translation of 0–5 mm (grade 1), 5–10 mm (grade 2), and >10 mm (grade 3)
    • 90% sensitive and 99% specific for diagnosing PCL tears
  • Posterior sag test:
    • Perform with the patient supine and knee flexed at 90 degrees and hip flexed at 45 degrees
    • Examiner stabilizes both heels.
    • Observe the knee from lateral perspective.
    • Normally, the tibial plateau sits ∼1 cm anterior to the femoral condyles.
    • An abnormal contour, or sag, of the tibial plateau in relation to the femoral condyles is consistent with PCL deficiency.
  • Quadriceps active test:
    • Perform with the patient supine and knee flexed at 90 degrees and hip flexed at 45 degrees
    • Examiner stabilizes the foot, and the patient attempts to extend the knee while the examiner applies a counter force against the ankle.
    • Patient also may be asked to activate quadriceps by sliding foot down the table.
    • In a PCL-deficient knee, the posteriorly subluxed tibia will translate anteriorly with quadriceps activated.
  • Dynamic posterior shift test:
    • Patient is supine with knee and hip flexed at 90 degrees.
    • Examiner slowly extends knee.
    • With a PCL tear, there will be “clunk” near full extension when the posteriorly subluxed tibia is reduced.

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Diagnostic Tests & Interpretation
Imaging
  • Radiographic evaluation with anteroposterior (AP), lateral, sunrise, and tunnel views to rule out bony avulsions, other fractures, or patellar subluxations
  • Oblique views are sometimes helpful to rule out tibial plateau fractures.
  • Flexion weight-bearing posteroanterior and patellar radiographs can help to distinguish early degenerative changes from chronic PCL deficiencies.
  • Stress radiographs: 8 mm or more posterior tibial translation is indicative of complete PCL tear.
  • Radionuclide bone scans are able to distinguish early degenerative changes in medial and patellofemoral compartments from chronic PCL deficiencies.
  • MRI:
    • Reported to be up to 100% sensitive and specific in evaluating complete PCL rupture.
    • Only about 67% sensitive in identifying partial PCL tears
    • Proton density sequence is more sensitive than T2-weighted images for identifying isolated PCL tears.
    • Also can evaluate other soft tissue pathology of the affected knee
Differential Diagnosis
  • ACL tear
  • Tibia or fibular fracture
  • Medial or lateral collateral ligament tear
  • Meniscal derangement
  • Posterolateral corner injury
  • Knee dislocation
Treatment
  • Acute treatment:
    • Ice
    • NSAIDs
    • Compression
    • Elevation
  • Immobilization:
    • Partial weight-bearing
    • Possible immobilization in full extension for grade 3 lesions
Additional Treatment
Additional Therapies
Early surgical repair is indicated for patients with associated avulsion fractures or other ligament involvement.
Surgery/Other Procedures
Indications include:
  • Associated bony avulsion fractures
  • Multiple ligament injuries
  • Persistent pain in grade 3 lesions
  • Chronic symptomatic instability with activities of daily living or with sports
  • Acute grade 3 injury in young, active patient
Ongoing Care
  • Grade 1 and 2 lesions:
    • Early range of motion
    • Aggressive quadriceps strengthening
    • Partial weight-bearing
    • Protection of knees against posterior sag
    • PCL brace may be useful but not proven effective.
  • Grade 3 lesions:
    • 2–4 wks of immobilization in full extension to protect posterolateral structures from posterior tibial translation
    • Early range of motion
    • Quadriceps strengthening with quadriceps sets and straight-leg raises
    • Hamstring strengthening
    • Partial weight-bearing
    • Functional PCL brace may be useful during activity but not proven effective.
Follow-Up Recommendations
  • Referral to orthopedic surgery if indicated, as above
  • Early orthopedic referral except in uncomplicated, isolated grade 1 and 2 lesions
  • Early physical therapy referral may be beneficial because loss of proprioception and sprint speed are major problems with return to play.
Complications
  • Nonoperative:
    • Chronic PCL laxity
    • Progressive medial compartment and patellofemoral degeneratative changes
  • Operative:
    • Most common: Residual laxity
    • Iatrogenic neurovascular injury (especially of the popliteal artery)
    • Loss of motion
    • Infection
    • Medial femoral condyle osteonecrosis
    • Anterior knee pain
    • Painful hardware
Additional Reading
Colvin AC, Meislin RJ. Posterior cruciate ligament injuries in the athlete—diagnosis and treatment. Bull NYU Hosp Jt Dis. 2009;67:45–51.
Cosgarea AJ, Jay PR. Posterior cruciate ligament injuries: evaluation and management. J Am Acad Orthop Surg. 2001;9:297–307.
Harner CD, Höher J. Evaluation and treatment of posterior cruciate ligament injuries. Am J Sports Med. 1998;26:471–482.
St Pierre P, Miller MD. Posterior cruciate ligament injuries. Clin Sports Med. 1999;18:199–221, vii.
Codes
ICD9
844.2 Sprain of cruciate ligament of knee
Clinical Pearls
  • In isolated grade 1 and 2 PCL tears, uncomplicated patients may be able to return to play within 2–4 wks depending on the sport.
  • In grade 3 injuries, uncomplicated patients may take up to 3 mos of rehabilitation before return to play.


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