COMPARISON OF MRI WITH
ARTHROSCOPY IN KNEE INJURIES
ABSTRACT ID NO: 68
…
 Introduction
 Aims and objectives
 Materials & Methods
 Results
 Discussion
 Conclusion
INTRODUCTION
 Knee joint is the largest and complex joint of the body and also most
frequently injured joint due to the lack of bony support. The stability of the
joint is highly dependent on its supporting ligamentous structures, therefore
injuries of ligaments and menisci are extremely common .
 Multiple modalities are currently used to evaluate pathologic conditions of knee
including conventional radiography, fluoroscopy, sonography, nuclear medicine
and magnetic resonance imaging (MRI). The use of conventional radiography
and CT limited to fractures and bone contusions.
 MRI has revolutionized our ability to understand the soft tissue anatomy and
pathology of musculoskeletal system. The role of MRI in imaging of knee has
steadily increased over years.
 Magnetic resonance imaging with its excellent soft tissue contrast,
multiplanar imaging capabilities, non invasive nature and lack of ionizing
radiation has overcome the limitation of other imaging modalities.
Hence it has become the best modality for pre operative planning of knee injuries.
AIMS AND OBJECTIVES

To assess the accuracy of MRI in patients with acute
knee pain
 To categorize the internal derangements in knee joint
by MRI before arthroscopy.
 Comparison of MRI with arthroscopy findings
MATERIALS & METHODS
 A prospective study involving 50 patients with
suspected internal derangement of knee referred to the
Department of Radiology. MRI knee joint was
performed on 1.5T for all these patients after clinical
examination. MRI positive patients were sent for
arthroscopy.
 Standard protocols: MR sequences included
sagittal
T1, T2 and PDFS images, coronal STIR images, axial
T2 and PDFS images.
RESULTS
TYPES OF INJURY AMONG THE AGE
GROUPS
DISTRIBUTION OF LESIONS IN STUDY GROUP
LESIONS GROUP
MRI
ARTHROSCOPY
ACL
34
35
PCL
5
5
MM
29
29
LM
21
18
Internal derangement observation based on MRI FINDINGS
MRI
No of cases
(total = 50)
Percentage
ACL TEAR
34
68
PCL TEAR
5
10
MEDIAL
MENISCAL TEAR
29
58
LATERAL
MENISCAL TEAR
21
42
Internal derangement observation based on Arthroscopy
ARTHROSCOPY
No of cases
(total = 50)
Percentage
ACL TEAR
35
70
PCL TEAR
5
10
MEDIAL
MENISCAL TEAR
29
58
LATERAL
MENISCAL TEAR
18
36
MRI AND ARTHROSCOPY CORRELATION IN DIAGNOSING ACL TEAR
MRI FINDINGS
ACL TEAR
TOTAL
ARTHROSCOPY
PRESENT
ABSENT
PRESENT
33
1
34
ABSENT
2
14
16
TOTAL
35
15
50
MRI showed 34 positive for ACL tears & Arthroscopy detected 35 patients . 1 patient had a false
positive MRI. But 2 patients out of 16 normal ACL reported by MRI had arthroscopic evidence of
ACL tears. Arthroscopy revealed normal ACL structure in one patient in which MRI had shown signs
of tear
MRI AND ARTHROSCOPY CORRELATION IN DIAGNOSING PCL
TEAR
MRI FINDINGS
PCL TEAR
ARTHROSCOPY
TOTAL
PRESENT
ABSENT
PRESENT
4
1
5
ABSENT
1
44
45
TOTAL
5
45
50
MRI AND ARTHROSCOPY CORRELATION IN DIAGNOSING MM TEAR
MRI FINDINGS:MEDIAL
ARTHROSCOPY
TOTAL
MENISCAL TEAR
PRESENT
ABSENT
PRESENT
22
2
24
ABSENT
3
23
26
TOTAL
25
25
50
MRI AND ARTHROSCOPY CORRELATION IN DIAGNOSING LM TEAR
MRI FINDINGS
LATERAL MENISCAL TEAR
ARTHROSCOPY
TOTAL
PRESENT
ABSENT
PRESENT
13
3
16
ABSENT
2
32
34
TOTAL
15
35
50
ADDITIONAL MRI FINDINGS
MRI FINDINGS
NO OF PATIENTS
MCL TEAR
14
LCL TEAR
10
JOINT EFFUSION
38
OSSEOUS AND
34
OSTEOCHONDRAL
LESIONS
Composite injuries
COMPOSIT
E INJURY
MRI
ARTHROSC
OPY
ACL + MM
10
12
ACL + LM
7
6
ACL +PCL
2
2
MM +LM
6
3
PCL +MM
-
1
PCL + LM
1
1
ACL +MM+
LM
5
4
ACL +PCL+
MM
1
-
OVERALL SENSITIVITY PROFILE OF MRI
PARAMETERS
ACL
PCL
MM
LM
Sensitivity
94.29 %
80.00 %
93.10 %
94.44 %
Specificity
93.33 %
97.78 %
90.48 %
87.50 %
Accuracy
94%
96%
92%
90%
DISCUSSION
Though injury to a knee joint can involve any intraarticular
and extraarticular structures,in our study group we gave
importance to cruciate ligaments and menisci lesions. They
were compared with arthroscopy and their diagnostic
efficiency were assessed. Other lesions were recorded and
their incidences were assessed
In this study;
 Right knee joint injuries were more common.
 Male preponderance with 78%.
 Most common in young age group, especially between 21
to 30 years who forms 46% of total cases and age group
between 31 to 40 years had 30% of total cases.
 Pain was the most common presenting symptom, occurring in 84% of
cases. Rest was found only in 20% of cases. These were primarily
used to select patients for further evaluation like MRI and
arthroscopy
 MRI revealed ACL tears in 68%, PCL tears in 10%, medial meniscus
tears in 58% and lateral meniscus tears in 42% of cases. In
comparison, arthroscopy revealed ACL tears in 70%, PCL tears in
10%, medial meniscus tears in 58% and lateral meniscus tears in 36%
of cases.
 Additionally, MCL tears in 28%, LCL tears in 20% and
osseous/chondral lesions in 68% of cases were also reported.
 Out of 31 patients who had bony bruises, 28 had ACL tears resulting
in good specificity (81%) and sensitivity (82%) for bony bruises to
predict ACL tear.
 PCL involvement is less common than ACL injuries.
 The menisci consists of fibrocartilage and has low signal
intensity on all image planes. The sensitivity and specificity in
detecting meniscal tears exceeds 90% if MRI is used
 Our study also noted lateral menisci involvement in 3 cases
where arthroscopy failed to detect these.
 Though we observed MRI and arthroscopy are equally good in
identifying medial menisci lesion, with respect to lateral menisci
involvement, MRI detected more lesions.
 Bony lesions were common in our observation consisting of
64% of cases. They most often present with associated
ligaments or menisci injuries
 When we analyzed the various combinations of composite
injuries, ACL and MM involvement was very common.
Combination of ACL and lateral meniscus lesions was next
common .ACL with both menisci tears present in 15% of total
composite injuries.
 Accuracy of MRI was studied extensively. Many studies
revealed the overall accuracy well above 90%. It has low
accuracy for PCL tears, while it has high accuracy for ACL
tears.
 MRI had very high sensitivity for lateral meniscus and very low
sensitivity for PCL tears.
 MRI had very high specificity for PCL tears but low specificity
for LM tears.
 This study assessed the sensitivity, specificity, negative predictive value
and positive predictive value for MRI, for various structural lesions in
internal derangement of knee joint, which is compared to arthroscopy.
MRI findings showed

Sensitivity 94.29 %, specificity 93.33 %, positive predictive value
97.06 % and negative predictive value 87.50 % for ACL tears .

Sensitivity 80.00 %, specificity 97.78 %, positive predictive value
80.00 % and negative predictive value 97.78 % for PCL tears.

Sensitivity 93.10 %, specificity 90.48 %, positive predictive value
93.10 % and negative predictive value 90.48 % for medial meniscal tears

Sensitivity 94.44 %, specificity 87.50 %, , positive predictive value
80.95 % and negative predictive value 96.55 %. for lateral meniscus tears.
 At the end, it appeared that MRI had directed us towards excess
arthroscopies in few cases and some missed lesions were found later by
arthroscopy.
 Thereby, in general, MRI findings of our study population were hand in
hand with arthroscopic findings, suggesting us to avoid unnecessary
arthroscopies which were invasive.
CONCLUSION
 Males and 21-30 age group were most commonly affected.
 ACL involvement was the most common presentation(68%).
 PCL involvement had lower sensitivity by MRI(80%).
 Most common composite injury pattern was the combination of ACL tears
and MM tears.
 MRI provides an ideal option of non invasive study of knee joint as
arthroscopy is invasive and has limitations in diagnosing few specific lesions
HENCE ......
 MRI was easy to use and efficient in patients with acute knee injuries.
 Overall accuracy of MRI is more than 90% for internal derangement
 MRI defined the anatomy of knee joint without need for intravenous
contrast agents or joint manipulation.
 MRI added more information than arthroscopy in the setting of
composite injuries of the knee.
ACL INJURIES
ACL Avulsion tear, fracture of tibial plateau with
hemarthrosis
PCL INJURIES
PCL Avulsion Tear with Posterior Tibial Subluxation
&Suprapatellar Bursal collection
MENISCAL INJURIES
MENISCAL EXTRUSION
DOUBLE PCL SIGN
COLLATERAL INJURIES
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