Korean J Radiol.  2016 Apr;17(2):239-244. 10.3348/kjr.2016.17.2.239.

Interposition of the Posterior Cruciate Ligament into the Medial Compartment of the Knee Joint on Coronal Magnetic Resonance Imaging

• Kim HS
• Yoon YC
• Park KJ
• Wang JH
• Choe BK

• KMID: 2360209
• DOI: http://doi.org/10.3348/kjr.2016.17.2.239

Abstract

OBJECTIVE
The purpose of our study was to evaluate the overall prevalence and clinical significance of interposition of the posterior cruciate ligament (PCL) into the medial compartment of the knee joint in coronal magnetic resonance imaging (MRI).
MATERIALS AND METHODS
We retrospectively reviewed 317 consecutive patients referred for knee MRI at our institution between October 2009 and December 2009. Interposition of the PCL into the medial compartment of the knee joint on proton coronal MRI was evaluated dichotomously (i.e., present or absent). We analyzed the interposition according to its prevalence as well as its relationship with right-left sidedness, gender, age, and disease categories (osteoarthritis, anterior cruciate ligament tear, and medial meniscus tear).
RESULTS
Prevalence of interposition of PCL into the medial compartment of the knee joint was 47.0% (149/317). There was no right (50.0%, 83/166) to left (43.7%, 66/151) or male (50.3%, 87/173) to female (43.1%, 62/144) differences in the prevalence. There was no significant association between the prevalence and age, or the disease categories.
CONCLUSION
Interposition of the PCL into the medial compartment of the knee joint is observed in almost half of patients on proton coronal MRI of the knee. Its presence is not associated with any particular factors including knee pathology and may be regarded as a normal MR finding.

Keyword

Knee; Posterior cruciate ligament; Anatomic variation; Magnetic resonance imaging

MeSH Terms

Adolescent
Adult
Aged
Child
Female
Humans
Image Processing, Computer-Assisted
Knee Joint/*radiography
*Magnetic Resonance Imaging
Male
Menisci, Tibial/radiography
Middle Aged
Osteoarthritis/diagnosis/epidemiology/radiography
Posterior Cruciate Ligament/*radiography
Prevalence
Retrospective Studies
Young Adult

Figure

• 

  Fig. 1 47-year-old woman with low grade chondral lesion at retro-patellar cartilage. Proton density weighted (repetition time, 2200 msec; echo time, 30 msec) coronal MR image of left knee. Medial margin of PCL is located lateral to line between inferomedial corner of medial femoral condyle and medial tibial spine (arrow). This case was classified as negative for interposition of PCL into medial compartment of knee joint. PCL = posterior cruciate ligament

• 

  Fig. 2 44-year-old woman with partial tear of anterior cruciate ligament. Proton density weighted (repetition time, 2200 msec; echo time, 30 msec) coronal MR image (A) of left knee shows focal outward bulging contour at medial margin of PCL, confined to medial side of line between inferomedial corner of medial femoral condyle and medial tibial spine (arrow). This case was classified as positive for interposition of PCL into medial compartment of knee joint. Arthroscopic image of medial compartment obtained with knee flexion position (B) shows same focal outward bulging contour of PCL (asterisk) between medial femoral condyle (MFC) and medial tibial plateau (MTP). PCL = posterior cruciate ligament

• 

  Fig. 3 49-year-old man with transverse tear of medial meniscus. Proton density weighted (repetition time, 2200 msec; echo time, 30 msec) coronal MR image (A) of left knee shows focal outward bulging contour at medial margin of PCL, confined to medial side of line between inferomedial corner of medial femoral condyle and medial tibial spine (arrow). This case was classified as positive for interposition of PCL into medial compartment of knee joint. Fat suppressed proton density weighted (repetition time, 2530 msec; echo time, 30 msec) axial MR image (B) shows full thickness transverse tear of medial meniscus posterior horn. Arthroscopic image of medial compartment obtained with knee flexion position (C) shows focal outward bulging contour of PCL (asterisk) between medial femoral condyle (MFC) and medial tibial plateau (MTP) and transverse tear of medial meniscus posterior horn (MMPH) (arrow). PCL = posterior cruciate ligament

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