X Ray and MRI of Knee Joint

X ray and MRI of Knee Joint

1. KNEE X RAY & MRI

2. TABLE OF CONTENTS Radiological Approach To Patient With Knee Condition Indications of Knee X Ray Various X ray Projections of Knee Normal Knee X ray Various Pathologies of Knee on X Ray MRI Knee Normal MRI knee Various Pathologies of Knee on MRI

3. Approach to Patient With Knee Pain

4. Approach to Patient With Knee Pain

5. Indications of Knee Joint X Ray Trauma Bony tenderness at the head of the fibula Isolated patella tenderness Patient unable to flex the knee to 90 degrees Patient is unable to bear weight Suspected osteoarthritis Detecting joint effusions Infection

6. To establish the presence of a fracture - imaged in at least two directions A standard examination includes an anterior-posterior image and a lateral image Additional directions may be added when indicated

7. AP VIEW In both supine and standing positions In supine position, the X-rays pass through the knee from anterior to posterior

8. STANDING AP VIEW An alternative to the supine position is the standing AP image. The knee is fully extended and imaged in the craniocaudal direction under a 10° angle.  Rosenberg method- knees should be flexed at 45° Standing images have the advantage over supine images that by the additional load on the knee joint M ore reliably detect reduced joint space caused by meniscus and cartilage disorders 

9. LATERAL VIEW Lateral images are made in the supine position with the knee flexed to 30°. The X-rays pass through the knee joint from medial to lateral 

10. In a trauma setting, an image using a horizontal x-ray beam may be preferred over the standard lateral image in order to establish Lipohemarthrosis The knee is fully extended and the X-rays pass through the knee from lateral to medial

11. AXIAL IMAGE The axial image is also termed the sunrise image and provides information on the patellofemoral joint.   Additionally, patellar pathology (fracture & subluxation/luxation in particular) can be identified. The patient is in the supine position and flexes the knee to 40-45° using knee support

12. TUNNEL VIEW I n a tunnel view, the intercondylar fossa is projected free.  It is used primarily to identify a free body or osteochondral defect . The patient is in the supine position and flexes the knee to 40-45° using knee support X-rays pass through the knee from anterior to posterior at a 90° angle to the lower leg.

13. NORMAL AP/PA VIEW The knee joint is formed by the femorotibial joint (femur - tibia articulation) and the patellofemoral joint (patella - femur articulation). The femorotibial joint is subdivided into the medial compartment and the lateral compartment.  T hey share a common articular capsule.   The femoral condyles and tibial plateau are visible on an AP/PA image. The lucent spaces at the level of the medial & lateral compartments of the femorotibial joint are the same in a normal knee. This space is indicative for the joint space.   An asymmetric joint space may suggest meniscus disorders and/or cartilage loss and/or ligament laxity.  The medial & lateral tibial plateau are separated by a minor elevation; the tibial intercondylar eminence.

14. MEASUREMNTS IN AP/PA VIEW Tibiofemoral alignment: on an AP/PA image, draw a vertical line along the lateral femoral condyle.  Be alert for a lateral tibial plateau fracture if the line is more than 5 mm lateral of the lateral tibial plateau

15. LATERAL IMAGE The lateral image produces a better image of the patellofemoral joint than the AP image. In addition to bone, we can also assess soft tissue. The knee has three fat pads Infrapatellar fat pad, also termed Hoffa's fat pad. 2.Posterior suprapatellar fat pad (= prefemoral fat). 3.Anterior suprapatellar fat pad. The posterior and anterior suprapatellar fat pads are separated by the suprapatellar recess. The suprapatellar recess is also termed the suprapatellar bursa and is connected to the femorotibial joint. In joint effusion, the recess may be distended. A normal knee has little fluid in the suprapatellar recess ( anterioposterior thickness <5 mm).

16. Importantly, it is more difficult to assess joint effusion as knee flexion increases. U nder flexion > 30°, the patella moves downward and the suprapatellar recess and surrounding soft tissues may be compressed/deformed. Consequently, small amounts of fluid stay unnoticed in the suprapatellar recess.

17. Measurements in Lateral Knee X Ray Patellar measurements in lateral image: The length of the tibial tubercle - patellar lower pole is about the same as the length of the patella, with a variation of 20%. The Insall-Salvati ratio is a commonly used measurement; it is the ratio between the length of the patellar tendon length and that of the patella Ideally, the measurement is performed with the knee flexed at 30°. In a normal knee, the ratio is between 0.8 - 1.2 (mean value = 1). If the ratio is < 0.8, the patella lies low (= patella baja ); I f the ratio is > 1.2, the patella lies high (= patella alta ). In the more recently developed modified Insall-Salvati ratio , the same measurement is performed, but the patellar tendon is measured up to the lower pole of the articulating portion of the patella. The patellar length includes the articulating portion of the patella. The mean normal value ratio is 1.25 and a ratio > 2.0 is considered diagnostic for patella alta.

18. In a tunnel view, the intercondylar fossa (= separation between the femoral condyles) is projected free. In a normal knee, there are no osteochondral defects or intra-articular bodies. The medial joint compartment has a slightly smaller joint space on the tunnel view than the lateral joint compartment. This is a normal finding. Explanatory note: the cartilage is slightly thinner on the contact point of the medial femoral condyle and the medial tibial plateau when the knee is flexed at 40-45° (= physiologic)

19. An axial (sunrise) image provides information on the patella and the patellofemoral joint.  During flexion/extension, the patella slides in the trochlea (notch) and is located in the middle of the trochlea. The patellofemoral joint has a medial facet and a lateral facet (with the crista in between), where the lateral facet is longer than the medial facet. Rule of thumb: the longest facet is the lateral side.   The contours are smooth everywhere and the joint space is symmetric at the medial and lateral sides.

20. A fabella is a common sesamoid bone in the lateral head of the gastrocnemius muscle.  It is located posteriorly from the femorotibial joint and is not to be confused with a fracture. On an AP image, a fabella projects over the lateral femoral condyle

21. The patella may arise from various ossification centers. Sometimes these centers are not fused, which is termed a bipartite patella. Rarer is the tripartite patella (3 ossification centers). The unfused center is located for the most part at the superolateral side. The ossification center must always have a rounded and sclerotic border, otherwise a patella fracture may be present.

22. In children (particularly age 10 - 15 years), a cortical irregularity/ lucency at the posteromedial side of the distal femur may be confused with an aggressive ossal lesion. This is the origin of the medial head of the gastrocnemius muscle (& insertion site of the adductor magnus muscle). The theory is that the irregularity is caused by traction of the above muscles. It is also termed a cortical desmoid.  A cortical desmoid may be associated with pain symptoms.  When in doubt about the presence of a cortical desmoid or possibly an ossal lesion, a radiologist should be consulted.

23. Non-dislocated fractures (dislocation = displacement) may be very subtle. A fracture is frequently associated with joint effusion.  The suprapatellar recess will fill with fluid/blood and the suprapatellar fat pads will expand 

24. In a trauma setting, a supine lateral image is recommended as this visualizes the fat-blood level; a lipohemarthrosis . Lipohemarthrosis is strongly associated with intra-articular fracture. It may occur also in a marked bony contusion or ligamentary lesion. In lipohemarthrosis , fat and blood are released into the joint from the bone marrow, creating a fat-blood level.

25. A tibial plateau fracture is a common knee fracture. Subtle fractures may be missed in a knee X-ray. When in doubt, a CT scan should be made (e.g. for lipohemarthrosis without obvious fracture on knee X-ray). The Schatzker classification is commonly used by surgeons/orthopedists and classifies tibial plateau fractures into 6 subtypes : Type I: wedge-shaped fracture of lateral tibial plateau, with < 4 mm depression* or dislocation Type II: split + compression fracture of lateral tibial plateau with > 4 mm depression (= type I with depression) Type III: pure depression fracture of lateral tibial plateau Type IV: medial tibial plateau fracture with split or compression component (poorest prognosis!) Type V:  Fracture of medial & lateral tibial plateau Type VI: transversal fracture through the metadiaphysis (involvement of medial/lateral tibial plateau is variable) * depression is measured as the vertical distance between the lowest point of the intact medial tibial plateau and the lowest point of the lateral tibial plateau fragment.

26. When a patellar fracture is suspected, an axial (sunrise) image should always be made. A vertical patellar fracture can be missed on the AP/PA image and the lateral image (fig. 24). Be aware of bipartite patella as a normal variation. A fracture has an irregular cortex interruption (vs. smooth sclerotic contours in a bipartite patella) and will not be present on old images.

27. The anterior cruciate ligament inserts on the medial tubercle (medial tibial spine) of the intercondylar eminence.  Following excessive stress, an avulsion fracture may develop on the anterior cruciate ligament. An intercondylar eminence fracture may occur in the elderly, particularly in the presence of osteoporosis.  Concomitant meniscus and ligamentary damage may be present. However, this occurs more frequently in adults after high-energy trauma.

28. A segond fracture is an avulsion fracture on the outer side of the lateral tibial plateau and may develop following internal rotation in combination with varus stress. M ay also involve the iliotibial ligament and a portion of the lateral collateral ligament.  A Segond fracture is can also be highly associated with rupture of the anterior cruciate ligament.

29. Repetitive microtrauma and traction of the patellar tendon at the level of the tibial tubercle may lead to Osgood-Schlatter disease. It is considered a chronic avulsion fracture of the proximal tibia and develops predominantly at age 10 - 14 years (boys > girls). The classical radiologic picture of Osgood-Schlatter disease is fragmentation of the tibial tubercle and local soft tissue swelling. There may also be obliteration of the caudal portion of Hoffa's fat pad (secondary to infrapatellar bursitis).

30. The patellofemoral joint is stabilized by the extensor muscles, the bone (trochlea) and ligaments (medial patellofemoral retinaculum/ligament). The patella may luxate towards lateral, frequently the result of a twisted leg; knee in flexion + internal rotation of the femur + fixated foot with a valgus component

31. Osteochondritis Dissecans Osteochondritis dissecans (OCD) is an osteochondral disorder that is observed in children/teenagers with joint pain, swelling and/or locked joints.  The exact etiology has not been elucidated.  It is likely a multifactorial process consisting of genetic factors, growth abnormalities and chronic subchondral stress.  At adult age (= mature skeleton) the term osteochondral lesion is used rather than OCD.   The disorder encompasses a spectrum starting at subchondral bone edema to subchondral fracture/fragmentation and eventually detachment of the osteochondral fragment

32. OSTEOARTHRITIS Radiological characteristics of osteoarthritis: Narrowing of the joint space secondary to meniscus pathology and to a lesser degree loss of cartilage  Subchondral sclerosis (increased bone production secondary to increased pressure with cartilage loss) Osteophyte formation (bone exostoses attempting to increase the joint surface) Subchondral cysts (secondary to microfractures of the subchondral bone and pressure of the synovial fluid) Synovitis

33. Patellofemoral osteoarthritis can be assessed on a lateral image and an axial image.  J oint space narrowing as a sign of osteoarthritis can frequently not be assessed adequately on Lateral X ray An axial image, however, will allow more accurate assessment of the joint space narrowing

34. MRI OF KNEE JOINT

35. B A SI C SEQUENCES I N M S K M RI

36. Proton-density-weighted sequences : they produce images with the highest signal-to-noise ratio and, therefore, provide better resolution than T2-weighted FSE images. USEFUL FOR MENISCI, CARTILAGE T1-weighted images: produce high a signal-to-noise ratio, useful in showing musculoskeletal anatomy. WORKHOUSE FOR ANATOMY. Fat appear bright signal/white. T2-weighted sequences : have the poorest signal-to-noise ratio, and therefore the poorest resolution, but they are used primarily for their fluid sensitivity and their ability to detect pathology that has a high fluid content (e.g., tendon or ligament tears, tumors). SIGNIFICANCE OF THE DIFFERENT SEQUENCES OF MRI

37. T1 W E I G HT E D I M A G I NG

38. GADOLINIUM ENHANCED T1 IMAGING

39. T2 WEIGHTED IMAGING

40. PROTON-DENSITY SE AND PROTON-DENSITY FSE

41. . L ike T2-weighted sequences with fat suppression, is excellent for detecting fluid and edema when administered with a long TE STIR can be used as an alternative to T2-weighted imaging. Change the appearance of white to black; highlighting liquids. On fluid-sensitive-images such as STIR, fluid appears bright and makes the edema and fluid associated with certain types of pathology more conspicuous than they are on non–fluid-sensitive sequences. Such pathology includes osteomyelitis, fasciitis, abscesses, metastases, primary bone tumors, fractures, tenosynovitis, tendon tears, and bone contusions. STIR(SHORT TAU INVERSION RECOVERY)

42. STIR

43. Fat remain bright and hence difficult to differentiate it from liquid. Hence fat suppression is required and can be performed using STIR CAN REDUCE METAL ARTEFACT SPIN ECHO

44. T1-weighted image T2-weighted image Intermediate-weighted or proton-density–weighted image Fluid-sensitive sequence, such as STIR or fat-suppressed T2-weighted image Gradient-echo image Postgadolinium T1-weighted image SEQUENCE OF MRI USED MOSTLY FOR MUSCULOSKELETAL SYSTEM

45. Suppression of signal from fat. Images appear darker than conventional T2 help accentuate the increase in T2-weighted signal (relative to the adjacent tissues) In evaluation of bone marrow edema and edema secondary to other pathologic processes. FAT-SUPPRESSED T2-WEIGHTED IMAGES OR STIR IMAGES

46. Trauma( hemarthrosis, meniscal tears, ACL tear, PCL tear, MCL and LCL tear, quadeiceps and patellar tendon rupture, etc) Degenerative conditions Infection I n f l a m m a t o r y Tumors M i s ce ll a n e o u s INDICATIONS OF MRI IN KNEE CONDITIONS

47. SAGITTAL C O R O N A L AXIAL SEQUENCE OF EVALUATION

48. SAGITTAL VIEW

49. V a st u s m edial i s Medial gastrocnemius Sartorius

50. Vastus medialis Medial femoral condyle Medial meniscus Tibia Medial g a stro cne m i u s Gracilis tendon Sartorius muscle

51. V a st u s m edial i s Medial femoral condyle Medial meniscus Tibia Semitendinosus tendon Medial g a stro cne m i u s muscle Medial gastrocnemius tendon Gracilis tendon

52. Posterior horn of medial meniscus Joint capsule Anterior horn of medial meniscus Semimembranosus tendon S e m iten d i no s u s tendon S e m imem b ra no s u s muscle

53. Shaft of the tibia Shaft of the femur

54. Infrapatellar fat pad P a tel l a Oblique popliteal ligament Posterior cruciate ligament P opl i t e u s m uscle

55. Posterior cruciate ligament P opl i t e a l a rtery Anterior cruciate ligament Patellard tendon Quadriceps tendon

56. T ibial ne r v e P opl i t e a l v ein Anterior cruciate ligament P opl i t e a l artery P opl i t e u s m uscle

57. Posterior horn of lateral meniscus

58. Quadriceps tendon Patella Patellar tendon T ibia Fe m u r

59. P opl i t e u s m uscle Posterior horn of lateral m eniscus P opl i t e u s t e ndon Head of fibula Anterior horn of lateral meniscus Lateral femoral condyle

60. Biceps femoris muscle Lateral head of gastrocnemius muscle Common peroneal nerve

61. Tendon of the lateral head of gastrocnemius Co m m on perone a l nerve La t e ral m eniscus Vastus lateralis muscle

62. Superior tibiofibular joint Tibialis anterior muscle

63. CORONAL VIEW

64. Biceps femoris tendon Biceps femoris P opl i t e a l a rtery Lateral head of gastrocnemius muscle Head of fibula S e m imem b ra no s u s muscle Gra ci l is tendon Semimembranosus tendon Medial head of g a stro cne m i u s muscle S e m iten d i no s u s tendon

65. Lateral superior geniculate artery S a rto r i u s muscle Medial inferior geniculate artery P opl i t e a l a rtery P opl i t e u s m uscle Biceps femoris tendon

66. Lateral femoral condyle Great saphe nou s vein P opl i t e u s m uscle

67. Lateral gastrocnemius tendon Medial g a stro cne m i u s tendon Medial femoral cond y le S a rto r i u s tendon Gra ci l is tendon Posterior cruciate ligament Lateral tibial plateau S e m imem b ra no s u s tendon Medial tibial plateau Great saphe nou s vein

68. La t e ral m eniscus Head of the fibula

69. Anterior cruciate ligament Lateral collateral ligament Medial collateral ligament

70. M e d ial f e m or a l condyle Lateral femoral condyle Popliteus tendon

71. Lateral inte rm usc u lar septum Anterior cruciate ligament Lateral meniscus Lateral intercondylar tubercle Medial intercondylar tubercle P o st e r i o r cruciate ligament

72. Vastus medialis muscle Anterior cruciate ligament

73. Iliotibial band

74. Iliotibial band

75. Anterior horn of m edial m eniscus

76. Infrapatellar fat pad Vastus lateralis tendon

77. Lateral retinaculum

78. Patella Lateral retinaculum Infrapatellar fat pad Patellar tendon Medial retinaculum Quadriceps tendon

79. A X I A L VI E WS

80. Tibial tuberosity Saphenous nerve Great saphenous vein Medial gastrocnemius Lateral gastrocnemius So l e u s T ibia Tibialis anterior Fib u la

81. Patellar tendon

82. Lateral tibial condyle Iliotibial tract Medial tibial condyle Sartorius tendon Gracilis tendon Semitendinosus tendon Semimembranosus tendon

83. Medial femoral condyle Lateral femoral condyle Infrapatellar fat pad Patellar tendon Popliteus tendon

84. Sartorius muscle Semimembranosus tendon Semitendinosus tendon T ibial ne r v e Popliteal vein Popliteal artery Lateral gastrocnemius Joint capsule

85. Superior medial geniculate artery Superior lateral geniculate artery Patella Synovial fluid

86. Popliteal artery and vein Semimembranosus muscle Biceps femoris Femur Vastus medialis Sartorius muscle Semitendinosus tendon Quadriceps tendon Suprapatellar bursa

87. MRI FINDINGS IN COMMON KNEECONDITIONS

88. MRI is commonly used to discern the etiology of an acute hemarthrosis, especially when the knee is too tender or the patient is too anxious for a thorough physical examination. MRI is especially helpful when conventional radiographs are negative. Typically, acute hemarthrosis appears as fluid within the joint with high signal intensity on T2-weighted images and intermediate signal intensity on T1-weighted images H E M A R THO R IS

89. BONE MARROW CONTUSIONS

90. M AR R O W ED E M A

91. Meniscal tears are graded according to how they appear on MRI and are best seen on T1-weighted, gradient-echo, and proton-density images. Menisci show low intensity on all sequences. uses MRI findings to categorize tears as follows Horizontal Vertical radial Vertical longitudinal with/without flap displacement Complex MENISCAL TEARS

92. HORIZONTAL TEAR OF POST. HORN OF MED. MENISCUS

93. GRADING OF MENISCAL TEARS

94. MENISCAL TEAR WITH CYST

95. VERTICAL RADIAL TEAR

96. VERTICAL RADIAL TEAR

97. VERTICAL LONGITUDINAL TEAR

98. DOUBLE PCL SIGN

99. AC L TE A RS

100. CHRONIC ACL TEAR

101. PCL TEARS

102. PARTIAL PCL TEAR

103. MCL TEAR

104. MCL TEAR

105. PATELLAR TENDON RUPTURE

106. PATELLA ALTA

107. PATELLA BAJA

108. CHONDROMALACIAE PATALLAE

109. QUADRICEPS TENDON RUPTURE

110. LOOSE BODIES

111. THANK YOU