Jason J. Lewis, HMS III
Gillian Lieberman, MD
BIDMC Radiology Core Clerkship
December 2009
Agenda
Presentation of our patient
Normal anatomy of the knee
Common sports related knee injuries
Menu of radiologic tests
Imaging algorithm for post-traumatic
knee pain
Our Patient: History and Physical
Exam
25-year-old female with no significant past medical or
past surgical history presents with left lateral knee pain
s/p soccer injury
Patient’s foot was caught in the turf, felt her left knee
shift
Heard a “pop” and needed to be helped off of the field
In ED, notable tenderness laterally and with varus
stress – originally diagnosed with knee sprain
In Ortho consultation two days later – walking with
limp, knee showed moderate effusion, motion of knee
was limited by pain, tenderness medially to palpation
along the joint line, grade 1-2 opening with valgus
stress, positive Lachman maneuver, no significant
opening with varus stress or with posterior lateral
rotation
Agenda
Presentation of our patient
Normal anatomy of the knee
Common sports related knee injuries
Menu of radiologic tests
Imaging algorithm for post-traumatic
knee pain
Knee Anatomy
The cruciate ligaments
(ACL and PCL) act as
major restraints to
lateral rotation as well
as antero-posterior
motion. They are
secondary restraints to
varus and valgus stress
The collateral ligaments
(MCL and LCL) support
the knee medially and
laterally and act as
secondary restraints to
lateral and antero-
posterior movement
http://www.conformis.com/Patients/About-Knee-Replacement-
surgery/Anatomy-of-a-KneeStork, A, et al. (2000)
Knee Anatomy Continued
Menisci are important for
knee function and
contribute to distributing
compressive and
torsional forces (1)
Vertically oriented forces
are converted into hoop
stress in the menisci
thereby decreasing axial
load on articular cartilage
(2)
Shock absorbers,
lubrication, provide
secondary stabilization
(2)
Thornton, DD and Rubin, DA (2000)
(1) Carrino, JA and Schweitzer, ME (2002)
(2) Thornton, DD and Rubin, DA (2000)
Agenda
Presentation of our patient
Normal anatomy of the knee
Common sports related knee injuries
Menu of radiologic tests
Imaging algorithm for post-traumatic
knee pain
Sports-Related Knee Injuries
In a 10-year-study following 6434 patients
with sports injuries related to the knee joint:
y ACL lesion (20.3%)
y Medial meniscus lesion (10.8%)
y Lateral meniscus lesion (3.7%)
y MCL lesion (7.9%)
y LCL lesion (1.1%)
y PCL lesion (0.65%)
Leading activities leading to injury were
soccer (35%) and skiing (26%)
Majewksi, M, et al. (2006)
Agenda
Presentation of our patient
Normal anatomy of the knee
Common sports related knee injuries
Menu of radiologic tests
Imaging algorithm for post-traumatic
knee pain
Menu of Radiologic Tests for Post-Trauma
Knee Pain
Plain radiograph
MRI
Arthrography
CT
Bone scan
Sonography
Single photon emission computed
tomography (SPECT)
CT angiography
Resnick, CS, et al. (2008) and Department of Health Western Australia (2007)
Plain Radiograph
Initial study of choice for evaluation of
post-traumatic knee pain and instability
Rule out any fracture
Can detect subtle fractures or avulsions
caused by detachment of the ligaments
Dislocation
Department of Health Western Australia (2007)
MRI
Study of choice for post-traumatic knee pain and instability
Can detect:
y Meniscal tears
y Ligament tears
y Bone contusions
y Osteochondral defects
y Also can detect less common pathologies
Advantages:
y Non-invasive
y No ionizing radiation exposure
y Superior soft tissue imaging
y Intra- and extra-articular processes imaged
y Multiplanar
y Cost-effective in reducing number of arhroscopies
Limitations:
y Decreased diagnostic ability with multiple knee injuries
y High cost and availability
Department of Health Western Australia (2007)
Arthrography
50%-75% accuracy in diagnosing
ligamentous and/or meniscal injuries
Has been replaced by MRI
Limitations:
y Only surface evaluation of menisci
Disadvantages:
y Invasive
y Injection of intra-articular contrast
y Ionizing radiation exposure
y Complications post-procedure
Department of Health Western Australia (2007)
CT
Comparable to MRI for tibial plateau fractures
Ruling out fracture in a significantly injured
patient
Useful for looking for retro-patellar problems
and loose bodies
Multi-slice has been shown to have high
accuracy in diagnosing ACL and related
meniscal lesions and articularpathology
Limited evaluation of soft tissue: difficult to
assess edema and strain on cartilage, menisci
and muscles
Department of Health Western Australia (2007)
Radionuclide Bone Scan
Can detect radiographically occult
injuries
Useful in chronic knee pathology
Focal increased uptake at sites of bone
repair: fractures, avulsions, torn menisci
or infarcations
Limitations:
y Non-specific
y Inferior anatomic definition
Department of Health Western Australia (2007)
Sonography
Has been reported to be 91% sensitive
and 100% specific for diagnosing an
acute ACL tear within 10 weeks of an
acute hemarthrosis when there is no
prior trauma or bone abnormalities
Highly operator dependent and most
U.S. institutions don’t have experience
with MSK ultrasound
Resnick, CS, et al. (2008)
SPECT
Proposed for diagnosing meniscal
injuries
A specific crescentic uptake pattern on
transaxial view has sensitivity of 77%
and specificity of 74% of identifying
meniscal tear
Resnick, CS, et al. (2008)
CT Angiography
Used mainly for blunt and penetrating
trauma to the knee
Can accurately assess injuries to the
extremity arteries
Resnick, CS, et al. (2008)
ACR Appropriateness Criteria for Acute
Knee Trauma: First Radiologic Study
Resnick, CS, et al. (2008)
Agenda
Presentation of our patient
Normal anatomy of the knee
Common sports related knee injuries
Menu of radiologic tests
Imaging algorithm for post-traumatic
knee pain
Imaging Algorithm
www.imagingpathways.health.wa.gov.au
Our Patient: Application of
Algorithm
Now that we’ve discussed the menu of
radiologic tests and an algorithm for
imaging lets return to our patient
Our patient had knee tenderness to
palpation laterally and with movement,
and was unable to bear weight
immediately after the injury
Following the Ottawa criteria, a plain
radiograph was indicated
Our Patient: Plain Radiograph of
the Knee
Plain radiograph of left knee (AP view)
taken in the ED
Findings:
-no fracture
-no dislocation
-no degenerative changes
-no joint effusion
-no foreign body
Impression:
-normal radiograph
PACS, BIDMC
Plain radiograph of left knee (oblique
view)
Findings:
-no fracture
-no dislocation
-no degenerative changes
-no joint effusion
-no foreign body
Impression:
-normal radiograph
PACS, BIDMC
Our Patient: Plain Radiograph of
Knee (oblique view)
Plain radiograph of left knee (lateral
view)
Findings:
-no fracture
-no dislocation
-no degenerative changes
-no joint effusion
-no foreign body
Impression:
-normal radiograph
PACS, BIDMC
Our Patient: Plain Radiograph of
Knee (lateral view)
Our Patient: Application of
Imaging Algorithm Continued
The plain films were normal; however,
on physical exam, our patient was found
to have signs of soft tissue damage:
y Positive Lachman test – indicative of an ACL
tear
y Grade 1-2 opening with valgus stress –
indicative of an MCL tear
Given the exam findings, an MRI is
indicated
Our Patient: ACL tear on T2 fat-saturated
MRI
PACS, BIDMC PACS, BIDMC
T2 FS MRI sagittal view of left knee:
-Full-thickness ACL tear in mid-portion with increased fluid signal
Companion Patient #1: Normal
ACL on T2 FS MRI
T2 FS MRI sagittal view of left knee:
-no increased fluid signal
-no evidence of tear
-normal ACL
PACS, BIDMCPACS, BIDMC
T2 FS MRI sagittal view of left knee:
-increased fluid signal indicative of
edema
-full thickness tear of ACL
Our patient Companion Patient #1
Our Patient: ACL tear on Proton
Density MRI
PD MRI sagittal view of left knee:
-Wavy, discontinuous appearance of ACL fibers on PD
-Border of ACL not parallel to Blumenstaat’s line
PACS, BIDMC PACS, BIDMC
Companion Patient # 1: Normal
ACL on PD MRI
PACS, BIDMC PACS, BIDMC
Our patient Companion Patient #1
PD MRI sagittal view of left knee:
-wavy, discontinuous fibers
-ACL not parallel to
Blumenstaat’s line
Our Patient: MCL tear on MRI
T2 fat saturated coronal image of
left knee:
-increased T2 signal in the MCL
and surrounding fascia indicating
edema
-thickening of MCL
-indicative of grade II MCL sprain/
tear
-bone marrow edema evident on
lateral femoral condyle
PACS, BIDMC
Grades of MCL sprain/tear on
MRI
Grade I:
y Edema and possibly hemorrhage, which
extends into the subcutaneous fat. The
ligament is continuous, thin and dark.
Grade II:
y Morphologic disruption or internal high signal
of fluid in the MCL bursa
Grade III:
y Complete disruption of the ligament
Stork, A, et al. (2000)
Our Patient: Lateral Meniscal
Tear on
MRI
PACS, BIDMC PACS, BIDMC
PD MRI sagittal view of left lateral knee (two contiguous images):
-Complex tear of the posterior horn of the lateral meniscus (grade 3)
Diagnosis of Meniscal
Tear by
MRI
The diagnosis of meniscal tear by MRI
requires that either of two criteria be met:
y Presence of increased intrameniscal signal on a
short TE image that definitively contacts an articular
surface
y Abnormal meniscal morphology in the absence of
prior meniscal surgery. The meniscus should have:
normal height, width and contour
Tears can be more confidently diagnosed
when seen on two or more contiguous images
or when seen on both the coronal and sagittal
planes
Thornton, DD and Rubin, DA (2000)
Grades of Meniscal
Signal on
MRI
Grade I:
y Irregular intrameniscal increased signal that does not
extend to the articular surface, and is believed to reflect
early degenerative findings or normal variation
Grade II:
y Signal is linear and may connect to capsular margin, and
is believed to reflect more severe degenerative findings
Grade IIc:
y Linear signal that extends to articular surface on a single
section
y Approximately 50% are tears
Grade III:
y Linear or complex signal that extends to the articular
surface on more than one section
Carrino, JA and Schweitzer, ME (2002)
Our Patient: Bone Marrow Edema
on MRI
PACS, BIDMC PACS, BIDMC
T2 FS MRI sagittal view of lateral left knee:
-Lateral femoral bone marrow edema
-BME of posterior margin of tibial plateau
-Indicative of kissing contusion
T2 FS MRI sagittal view of medial left knee:
-Posterior medial tibial plateau BME
Kissing Contusions
Common secondary finding in acute ACL
injury
Most common is BME in lateral femoral
condyle and posterolateral tibia
Caused by tibia rotation internally relative to
the femure leading to the lateral femoral
condyle being compressed against the
posterior lateral tibial plateau
ACL tear has also been associated with BME
in the posterior lip of the medial tibial plateau
Stork, A, et al. (2000)
Our Patient: Possible Tear of
Medial Meniscus on MRI
T2 FS MRI coronal view of left knee:
-abnormal signal in the medial
portion of the medial meniscus,
but does not appear to reach
articular surface
-indicates possible tear of medial
meniscus
PACS, BIDMC
Our Patient: Normal PCL on
MRI
PACS, BIDMC PACS, BIDMC
T2 FS MRI (left image) and PD MRI (right image) sagittal view of left knee:
-normal appearing, intact PCL
-well defined borders, homogenous signal intensity, boomerang appearance
that is convex posteriorly
Our Patient: Summary of
Radiologic Findings
ACL tear with kissing contusions
Grade II MCL sprain
Lateral meniscal tear
Suspected medial meniscal tear
Intact PCL
O’Donoghue’s
Unhappy Triad
Original inclusion criteria (1):
y Rupture of the medial collateral ligament
y Damage to the medial meniscus
y Rupture of the anterior cruciate ligament
New findings:
y 80% of ACL/MCL injuries are associated with lateral meniscus
tear (1)
y Medial meniscus tears were only found in 25% of these cases
and only in conjunction with torn lateral meniscus (1)
y A second study also found that lateral meniscus tears far out
numbered medial meniscus tears in patients with ACL/MCL
injuries (2)
y Both studies concluded that the classic O’Donoghue triad is
unusual clinically and is better described as ACL, MCL and
lateral meniscus
(1) Barber, FA (1992)
(2) Shelbourne, KD and Nitz, PA (1991)
Companion Patient #2: Segond
Fracture on Plain Film
Plain film (AP view) of left
knee:
-acute fracture arising
from lateral aspect of
left proximal tibia
-likely Segond fracture
PACS, BIDMC
Segond
Fracture
The Segond fracture results from
excessive internal rotation combined
with flexion of the knee
It is an avulsion fracture of the insertion
site of the meniscotibial portion of the
lateral capsular ligament
Associated with ACL tears in 75%-100%
of patients
Valkering, KP and Breederveld, RS (2008)
Companion patient #2: ACL Tear
on MRI
T2 fat-saturated sagittal view of left
knee:
-tear of the ACL with increased
fluid signal
PACS, BIDMC
Companion Patient #2: Partial
PCL Tear on MRI
T2 fat-saturated sagittal view of left
knee:
-abnormal high signal near distal
tibial attachment representing
partial tear of PCL
PACS, BIDMC
Companion Patient #3: LCL tear
on MRI
Stork, A et al. (2000)
T2 FS coronal image of
knee:
-tear of lateral collateral
ligament at the femoral
attachment with increased
signal
Our Patient: Follow-up
The MCL was allowed to heal on its own for 6
weeks in a hinge brace until full extension and
125 degrees of knee flexion were achieved
The ACL was reconstructed with autologous
hamstring graft with the semitendinosus and
gracilis tendons harvested
The lateral meniscus tear was not deemed
appropriate for healing and patient underwent
arthroscopic partial lateral meniscectomy
Post-surgical physical therapy to regain
strength and motion
Summary
Sports-related knee trauma can include any of the
ligaments or menisci
Plain film is the initial study of choice for acute knee
trauma, but one should follow the Ottawa Criteria
MRI is the study of choice
The classic O’Donoghue’s unhappy triad consists of
ACL, MCL and medial meniscus injuries
The common clinical “terrible triad” is actually ACL,
MCL and lateral meniscus injury
ACL tear is associated with:
y Kissing contusions (seen in index patient)
y Segond fracture (seen in companion patient #2)
References
Barber, FA. (1992). What is the Terrible Triad? Arthroscopy: The Journal of Arthroscopic and
Related Surgery 8(1), 19-22.
Carrino, JA and Schweitzer, ME. (2002). Imaging of sports-related knee injuries. Radiologic
Clinics of North America 40, 181-202.
Conformis (2009). Anatomy of a knee. Obtained from the world wide web:
http://www.conformis.com/Patients/About-Knee-Replacement-Surgery/Anatomy-of-a-Knee on
12/8/2009
Department of Health Western Australia (2007). Diagnostic Imaging Pathways: Post-traumatic
knee pain or instability. Obtained from the world wide web:
http://www.imagingpathways.health.wa.gov.au/includes/DIPMenu/knee_p/Summary.html on
12/8/2009
Majewski, M, Susanne, H, and Klaus, S. (2006). Epidemiogy of athletic knee injuries: A 10-year
study. Knee 13(3), 184-188.
Resnick, CS et al. (2008). ACR Appropriateness Criteria: Acute Trauma to Knee. Obtained from
the world wide web:
http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx on
12/8/2009
Shelborune KD and Nitz PA. (1991). The O’Donoghue triad revisited. Combined knee injuries
involving anterior curciate and medial collateral ligament tears. The American Journal of Sports
Medicine 19(5), 474-477.
Stork, A, Feller, JF, Sanders, TG, Tirman, PFJ, and Genant, HK. (2000). Magnetic Resonance
Imaging of the Knee Ligaments. Seminars in Roentgenology XXXV(3), 256-276.
Thornton, DD and Rubin, DA. (2000). Magnetic Resonance Imaging of the Knee Mensici.
Seminars in Rentgenology XXXV(3), 217-230.
Valkering, KP and Bredderveld, RS. (2009). Segond Fracture. Journal of the American College
of Surgeons 208(4), 646.
Acknowledgements
Dr. Gillian Lieberman
Dr. Rich Rana
Dr. Sachin Pandey
Maria Levantakis
Slide Number 1
Agenda
Our Patient: History and Physical Exam
Agenda
Knee Anatomy
Knee Anatomy Continued
Agenda
Sports-Related Knee Injuries
Agenda
Menu of Radiologic Tests for Post-Trauma Knee Pain
Plain Radiograph
MRI
Arthrography
CT
Radionuclide Bone Scan
Sonography
SPECT
CT Angiography
ACR Appropriateness Criteria for Acute Knee Trauma: First Radiologic Study
Agenda
Imaging Algorithm
Our Patient: Application of Algorithm
Our Patient: Plain Radiograph of the Knee
Our Patient: Plain Radiograph of Knee (oblique view)
Our Patient: Plain Radiograph of Knee (lateral view)
Our Patient: Application of Imaging Algorithm Continued
Our Patient: ACL tear on T2 fat-saturated MRI
Companion Patient #1: Normal ACL on T2 FS MRI
Our Patient: ACL tear on Proton Density MRI
Companion Patient # 1: Normal ACL on PD MRI
Our Patient: MCL tear on MRI
Grades of MCL sprain/tear on MRI
Our Patient: Lateral Meniscal Tear on MRI
Diagnosis of Meniscal Tear by MRI
Grades of Meniscal Signal on MRI
Our Patient: Bone Marrow Edema on MRI
Kissing Contusions
Our Patient: Possible Tear of Medial Meniscus on MRI
Our Patient: Normal PCL on MRI
Our Patient: Summary of Radiologic Findings
O’Donoghue’s Unhappy Triad
Companion Patient #2: Segond Fracture on Plain Film
Segond Fracture
Companion patient #2: ACL Tear on MRI
Companion Patient #2: Partial PCL Tear on MRI
Companion Patient #3: LCL tear on MRI
Our Patient: Follow-up
Summary
References
Acknowledgements