MyPACS.net: Radiology Teaching Files > Case 5549939

never visited POSTERIOR CRUCIATE LIGAMENT (PCL) TEAR
Contributed by: Radiology Residency Program Faculty & Staff.
Patient: 22 year old male
History: 22 year old male with pain, injured right knee in baseball game on 7/23/2006. Swollen, struggling with flexion.
Images:[small]larger

Fig. 1: Sagittal Proton Density

Fig. 2: Sagittal Proton Density with Fat Saturation
Findings: Fig. 1 and 2: Sagittal Proton Density without and with fat saturation images show the posterior cruciate ligament to be thickened with abnormal intrasubstance signal, and disruption of the fibers along its middle third.Mild edema is noted along the interstitial fibers of the anterior cruciate ligament, compatible with grade I sprain. A joint effusion is present. There is edema in the popliteal soft tissue.
Diagnosis:

Complete Tear Posterior Cruciate Ligament

Grade I Sprain Anterior Cruciate Ligament

Discussion:

Posterior Cruciate Ligament (PCL) Tear

- disruption of the PCL usually after forced posterior displacement of the tibia

- discontinuous and/or thickened PCL fibers of increased signal intensity on all pulse sequences
- PCL is twice as strong as ACL
- accounts for only 5-20% of all knee ligament injuries

Etiology:
- most commonly occurs by direct trauma impacting the anterior knee in a posterior direction (dashboard injury with the knee in flexion)
- also occurs in hyperextension, dislocation and rotational injuries

Radiographic Findings:

- Avulsion fractures of the posterior tibia

- Subtle anterior impaction fractures
- Reverse Segond Fracture rare

MR Findings:
T1WI
- Complete rupture - increased signal intensity and discontinuous fibers
- Partial tear - variable thickening, increased signal intensity and continuous fibers partially intact
- If there is an associated avulsion fracture of posterior mid tibia --> Hypointense fracture line surrounded by less hypointense edema

T2WI
- Interstitial tear: diffuse thickening, increased signal intensity
- Complete rupture: Increased signal intensity, and discontinuous fibers
- Partial tear: variable thickening, increased signal intensity, continuous fibers partially intact
- Coronal Images - thickening and increased intensity within the medial intercondylar notch
- Increased signal intensity anterior tibia and anterior femur "kissing fractures" = hyperextention injury

Differential Diagnosis
Mucoid Degeneration
Osteochondral injuries, i.e. "kissing fractures" of hyperextension in absence of PCL tear
PCL Graft Surgery
Posterolateral Corner (PLC) Injury

References:

Stoller, David W. ...[et al.] Diagnostic Imaging: Orthopaedics. Amirsys, 2004.

Submitted by:

Aakash D. Singh, M.D. PGY-V Radiology Resident
Mark R. DeGalan, M.D., Ph.D. - Radiologist
Mercy Medical Center

Comments:
No comments posted.
Additional Details:

Case Number: 5549939Last Updated: 08-10-2006
Anatomy: Skeletal System   Pathology: Trauma
Modality: MRExam Date: 07-27-2006Access Level: Readable by all users
Keywords: pcl tear, posterior cruciate ligament tearACR: 4526.4857

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