Sprained Ligaments of the Knee

Transcription

1 July 2001 Sprained Ligaments of the Knee Vinh Chung, Harvard Medical School Year III

2 Agenda Introduction Diagnostic Procedures MRI Images Our Patient Summary 2

3 Introduction The knee is the most commonly injured joint Most common orthopedic problem in the ED with 1.3m ED cases per year Over 50,000 knee injuries require operations in the U.S. each year Knees are the most common joints examined by MRI Injuries continue to increase due to sports activities Roberts, DM. Emergency department evaluation and treatment of knee and leg injuries. Emerg Med Clin North Am Feb; 18(1): 67-84, v-vi. Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed., 1998 Mosby-Year Book, Inc. 3 Tandeter, Howard. Acute Knee Injuries: Use of Decision Rules for Selective Radiograph Ordering. American Family Physican. December, Vol. 60: 9.

4 Ligament Anatomy Netter, Frank. Atlas of Human Anatomy. Second Edition. Novartis: New Jersey P

5 Anterior Cruciate Ligament vs. Posterior Cruciate Ligament Ligament Size Location Function ACL Smaller Anterior tibia to lateral condyle Prevent hyperextension and posterior displacement of femur PCL Larger Posterior tibia to medial condyle Prevent hyperflexion and anterior displacement of femur 5

6 Ligament Injuries Ligament Force Cause Frequency Anterior Cruciate Lateral w/ Knee Extended Sports 60% Posterior Cruciate Frontal w/ Knee Flexed MVA 3-10% Lateral Collateral Medial Medial Collateral Lateral Rare Common Southmayd, William. Sports Health: The Complete Book of Athletic Injuries. Quick Fox: New York P Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed., Mosby-Year Book, Inc. 6

7 Meniscus Anatomy 52% of injuries occur with ACL tears Failure to repair damage may speed up articular degeneration Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed., Mosby-Year Book, Inc. Netter, Frank. Atlas of Human Anatomy. Second Edition. Novartis: New Jersey P

8 1959 Description Anterior Cruciate Ligament Medial Collateral Ligament Medial Meniscus O Donoghue Triad Arthroscopy & MRI Anterior Cruciate Ligament Medial Collateral Ligament Lateral Meniscus Southmayd, William. Sports Health: The Complete Book of Athletic Injuries. Quick Fox: New York P. 248 Adalberth, T. Magnetic Resonance Imaging, scintigraphy, and arthroscopic evaluation of traumatic hemarthrosis of the knee. Am J Sports Med Mar-Apr; 25(2):

9 Treatment RICE: Rest, Ice, Compression, Elevation Surgery Severity Treatment Duration Grade I RICE 5 14 days Grade II RICE days Grade III RICE / Surgery Months 9

10 Diagnostic Algorithm History / Physical Exam Suspect Arterial Damage Arteriogram No Diagnosis Plain Films Fracture No Fracture CT Grade III MRI / Arthroscopy Diagnosis Grade I or II RICE Treatment Pain Ultrasound Diagnosis / Treatment 10

11 History and Physical Exam Cheap Advantages Non-invasive Can identify most knee joint lesions 90% sensitive in detecting ACL injuries Disadvantages 58% accuracy compared with arthroscopy Very difficult to diagnose: chondral fractures, loose bodies, and fibrotic fat pads 38-95% accurate in diagnosing ACL injuries Strobel, Michael. Diagnostic Evaluation of the Knee. Springer-Verlag Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed., Mosby-Year Book, Inc. Tandeter, Howard. Acute Knee Injuries: Use of Decision Rules for Selective Radiograph Ordering. American Family Physican. December, Vol. 60: 9. 11

12 Plain Films Cheap Advantages Non-invasive Rules out fractures and foreign bodies Disadvantages Overly used: 85% of knee injuries seen in ED get radiographs, but only 6-12% yield fractures Cannot image meniscus or ligament Roberts, DM. Emergency department evaluation and treatment of knee and leg injuries. Emerg Med Clin North Am Feb; 18(1): 67-84, v-vi. Tandeter, Howard. Acute Knee Injuries: Use of Decision Rules for Selective Radiograph Ordering. American Family Physican. December, Vol. 60: 9. 12

13 Plain Film ACL Avulsion Bony ligament avulsion apparent at tibial intercondyle eminence Strobel, Michael. Diagnostic Evaluation of the Knee. Springer-Verlag

14 CT Athrogram Advantages Excellent for fractures Good for ligament and meniscal tears Used if MRI contraindication Intact ACL Torn ACL Disadvantages Not as good as MRI May be painful Strobel, Michael. Diagnostic Evaluation of the Knee. Springer-Verlag

15 Arthroscopy Therapeutically, the most commonly performed orthopedic surgical procedure Diagnostically, the gold standard for intra-articular pathology of the knee, but has been replaced by MRI Advantages 84-97% accuracy in diagnosing knee pathology Excellent for treatment Simultaneous therapy through ligament debridement or reconstruction Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed., Mosby-Year Book, Inc. Disadvantages Invasive Cannot see posterior meniscal tear Difficult to see PCL 15

16 Advantages No radiation Non-invasive Highly sensitive and specific for diagnosing ligament and meniscal lesions Aid for pre-operative planning Can preclude unnecessary arthroscopy MRI Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed., Mosby-Year Book, Inc. Gray, Scott. Imaging of the Knee. Current Status. Orthopedic Clinics of North America. October Volume 28: 4. Disadvantages Expensive, $600-$1,200 16

17 Vinh Chung MRI Knee Coil Knee coils eliminate image distortions Patient is supine, hip fully extended, and knee slightly flexed Complete exam takes 20 minutes 17 Strobel, Michael. Diagnostic Evaluation of the Knee. Springer-Verlag

18 Normal ACL and PCL ACL PCL Visualized as linear low signal ligament strand (blue arrows) Less homogeneous than PCL Parallels roof of intercondylar notch (yellow arrows) Uniformly low in signal intensity Curves superiorly and anteriorly from the tibia to femur Gray, Scott. Imaging of the Knee. Current Status. Orthopedic Clinics of North America. October Volume 28: 4. Diagnostic Evaluation of the Knee. Springer-Verlag

19 Complete ACL Tear Poorly defined, mixed signal intensity at location where ACL should be. This is due to blood and edema High intensity (F) is joint effusion Gray, Scott. Imaging of the Knee. Current Status. Orthopedic Clinics of North America. October Volume 28: 4. 19

20 Acute PCL Tear High signal intensity wavy fibrids where PCL should be located. This represents hemorrhage and edema Gray, Scott. Imaging of the Knee. Current Status. Orthopedic Clinics of North America. October Volume 28: 4. 20

21 Normal Menisci Proton density-weighted sagittal images of two C-shaped menisci with the curves extending peripherally Lateral meniscus peripherally Lateral meniscus slightly more centrally resembles a bow-tie Lateral meniscus centrally through the two horns shows two triangles Medial meniscus centrally through horns demonstrates two triangles Thornton, Dean and David A. Rubin. Magnetic Resonance Imaging of the Knee Menisci. Seminars in Roentgenology. Volume: 21 35:3. July 2000.

22 Meniscal Tear High signal intensity in posterior horn of medial meniscus extending to the surface indicates clinically significant tear Gray, Scott. Imaging of the Knee. Current Status. Orthopedic Clinics of North America. October Volume 28: 4. 22

23 Our Patient HPI: PE: Plain Films: 46 year-old white male with a basketball injury of left knee Suggests meniscus tear Negative for fractures and bony avulsions An MRI is indicated 23

24 Diagnostic Algorithm History / Physical Exam Suspect Arterial Damage Arteriogram Fracture CT No Diagnosis Plain Films No Fracture Grade III MRI Diagnosis Grade I or II RICE Treatment Ultrasound Pain Diagnosis / Treatment 24

25 Our Patient: Normal Menisci Menisci are normal in signal intensity and morphology in both lateral and medial compartment. Cartilage is preserved 25

26 Our Patient: Bone Contusions In the lateral compartment, bony contusions involving lateral femoral condyle and proximal tibia 26

27 Our Patient: ACL Tear Increased signal intensity, wavy fibrids where ACL should be. All of these signs suggest complete ACL tear. 27

28 Our Patient: Normal PCL PCL is intact and normal in signal intensity. 28

29 Our Patient: Medial Collateral Ligament: Grade II Sprain There is increased signal intensity surrounding the medial collateral ligament. MCL is partially torn. 29

30 Summary of MRI Findings Ruled Out: on our patient Mensical tear Ruled In: Complete ACL tear Bone contusions Medial collateral ligament, grade II sprain 30

31 Diagnostic Procedure Comparison HPI / PE Plain Film CT US ART MRI Accuracy: Risks: Costs: 31

32 Summary Knee injuries, especially ligament tears, are very common History and physical examination are valuable, but sometimes insufficient to diagnose ligament tears MRI is the superior diagnostic tool for ligament injuries of the knees 32

33 References Adalberth, T. Magnetic Resonance Imaging, scintigraphy, and arthroscopic evaluation of traumatic hemarthrosis of the knee. Am J Sports Med Mar-Apr; 25(2): Gray, Scott. Imaging of the Knee. Current Status. Orthopedic Clinics of North America. October Volume 28: 4. Netter, Frank. Atlas of Human Anatomy. Second Edition. Novartis: New Jersey Roberts, DM. Emergency department evaluation and treatment of knee and leg injuries. Emerg Med Clin North Am Feb; 18(1): 67-84, v-vi. Rosen, Peter. Emergency Medicine: Concepts and Clinical Practice, 4th ed., 1998 Mosby-Year Book, Inc. Strobel, Michael. Diagnostic Evaluation of the Knee. Springer-Verlag Tandeter, Howard. Acute Knee Injuries: Use of Decision Rules for Selective Radiograph Ordering. American Family Physican. December, Vol. 60: 9. Thornton, Dean and David A. Rubin. Magnetic Resonance Imaging of the Knee Menisci. Seminars in Roentgenology. Volume: 35:3. July

34 Acknowledgements Larry Barbaras Cara Lyn D amour Daniel Lim Daniel Saurborn Leisle Chung 34