The Knee PDF Diagnostic Radiography Methods 1

THE KNEE MRSC1150 DIAGNOSTIC RADIOGRAPHY METHODS 1 ANATOMY:  Medial and lateral femoral condyles (medial larger than lateral)  Tibial plateaus  Intercondylar eminences or spines  Medial and lateral tibial condyles  Femur  Patella  Tibia  Fibula  Femur ...

THE KNEE MRSC1150 DIAGNOSTIC RADIOGRAPHY METHODS 1 ANATOMY:  Medial and lateral femoral condyles (medial larger than lateral)  Tibial plateaus  Intercondylar eminences or spines  Medial and lateral tibial condyles  Femur  Patella  Tibia  Fibula  Femur  Tibia  Fibula  Patella  Tibial Tuberosity  Medial + Lateral Femoral Condyles THE JOINTS:  Patellofemoral joint  Proximal Tibiofibular joint  Medial and Lateral Femorotibial joints  LIGAMENTS:  Lateral and Medial Collateral Ligaments (LCL and MCL)  Strengthen the medial and lateral aspects of the joint  Anterior Cruciate Ligament (ACL)  Located in the centre of the knee  Controls rotation and forward movement of the tibia  Posterior Cruciate Ligament (PCL)  Located in the centre of the knee https://www.spectrumhealthlakeland.org/lakeland-  Controls backward movement of neurosurgery/neurosurgery-health-library/Content/85/P07388/ the tibia  3 YEAR OLD KNEE OSSIFICATION CENTRES: Patella starts to be seen on an x-ray between 2-6 years old Growth plates usually fuse around puberty INDICATIONS:  Trauma  Cuts  Acute Sporting Injury  Bruising  Pain  Clicking  Lumps  Loss of function  Foreign Body  Deformity  Swelling  Reduced Range of Movement (ROM)  Infections  Mobile Patella  Previous Surgery PREPARATION:  Correct Patient Identification  Pregnancy Check (if applicable)  Explanation of Procedure  Remove necessary clothing, gown with opening to the back  Patient to lay on the x-ray table  Lead apron  AP KNEE: Xray: AP Knee kVp: 60-70kVp mAs: 7-10mAs FFD: 100-110cm CR: 24x30 plate DR: Imaging Receptor Cassette: Long axis of image receptor parallel with long axis of affected leg Centre: Centre approx. apex of patella Collimation: Four sides to the outer margins of the knee. Include to skin edge. Pt supine with both legs extended Image receptor is behind the affected knee Patient Position: Femoral condyles equidistant to imaging receptor Leg is slightly rotated inward (internally rotate) to place knee in a true AP position. Bontrager’s Handbook of Radiographic Positioning and Techniques EVALUATION CRITERIA AP KNEE:  Regional anatomy included – distal femur and proximal tibia and fibula, including soft tissue  Femorotibial joint space open  Femoral and tibial condyles should appear symmetrical  Patella superimposed on midline of femur  Medial half of fibula head superimposed on tibia  Density and contrast optimal to visualise bone & soft tissue https://radiopaedia.org/cases/normal-knee-x-rays AP WEIGHT-BEARING KNEE:  Often done bilaterally. Position as per AP Knee view  Patient needs to stand straight, knees fully extended and body weight equally distributed on the feet  Centre between both knees  Weight-Bearing may reveal narrowing of joint spaces that often appears normal on non-weight-bearing view  Used for osteoarthritis, orthopaedics, pre/post op, varus/valgus deformity AP INTERCONDYLAR KNEE: Xray: Intercondylar Knee kVp: 60-70kVp mAs: 7-10mAs FFD: 100-110cm CR: 24x30 plate DR: Imaging Receptor Cassette: Long axis of cassette perpendicular with long axis of affected leg CR will be perpendicular to the long axis of the tibia, parallel to tibial plateau Centre: CR will enter knee 1cm distal to apex of patella Collimation: Sufficient to include the bounds of the knee joint so soft tissue edge. Landscape rectangular shape Pt supine- Flex affected knee by 40-60 degrees depending on patient presentation Ensure no rotation of the leg internally /externally Patient Position: Get the imaging plate as close to the posterior side of the knee as possible- place sponges/other support needed Intercondylar Fossa- PA Axial EVALUATION CRITERIA INTERCONDYLAR KNEE:  Regional anatomy included – distal femur and proximal tibia and fibula, including soft tissue  Intercondylar fossa open (not superimposed by apex of patella)  Femorotibial joint space open  Intercondylar eminence separated and in the center of the intercondylar fossa  No rotation- Femoral and tibial condyles appear symmetrical  Density and contrast optimal to visualise bone & soft tissue http://www.wikiradiography.net/page/Supine _Intercondylar_Knee_Radiography PA WEIGHT-BEARING KNEE ROSENBERG VIEW:  Rosenberg view is usually done bilaterally  Pt is erect facing upright bucky  Knees bent 45deg, resting knees against upright bucky  CR- Angle the x-ray tube 10deg caudad- centre at the level of knee joint  The maximum stresses in the knee joint occur between 30o - 60o of flexion.  The Rosenberg view is more sensitive for joint space narrowing (cartilage loss) than the weightbearing AP views and is useful for the assessment of knees with early degenerative change. Merrill’s Atlas of Radiographic Positioning and Radiologic Procedures  LATERAL KNEE: Xray: Lateral Knee kVp: 60-70kVp mAs: 7-10mAs FFD: 100-110cm CR: 24x30 plate DR: Imaging Receptor Cassette: Long axis of image receptor parallel with long axis of affected leg Centre: Medial aspect of knee joint Collimation: Four sides to the outer margins of the knee Pt to roll onto affected side, to superimpose the femoral epicondyles Flex knee 20-30deg Patient Position: Place a sponge under the ankle so the long axis of the tif/fib is parallel to image receptor Other leg can be either behind or in front of affected leg Angle central ray 4-7deg cephalad, depending on patient presentation Merrill’s Atlas of Radiographic Positioning and Radiologic Procedures EVALUATION CRITERIA LATERAL KNEE:  Regional anatomy included – distal femur and proximal tibia and fibula, including soft tissue  Femoropatellar joint space open  Femoral condyles should appear superimposed  Patella in profile  Fibular head only slightly superimposed over tibia  Density and contrast optimal to visualise bone & soft tissue https://radiopaedia.org/cases/normal-lateral-knee-radiograph HORIZONTAL BEAM LATERAL KNEE:  Used for acute knee injuries  Detects lipohaemarthrosis = intra-articular fracture with escape of fat and blood from the bone marrow into the joint  Demonstrates a fluid level in the suprapatellar pouch  Approx. 5 degrees caudal angulation https://radiopaedia.org/articles/knee-horizontal-beam-lateral-view-1 Horizontal Beam Lateral Patella movement  Angle of tube depends on the flexion of the knee AXIAL PATELLA / SKYLINE VIEW: Xray: Skyline Knee kVp: 60-70kVp mAs: 7-10mAs FFD: 100-110cm CR: 24x30 plate DR: Imaging Receptor Cassette: Long axis of image receptor perpendicular with long axis of affected leg Centre: Centre to apex of patella Collimation: Four sides to the outer margins of the patella and joint space Pt supine with affected leg extended Bend affected knee 45deg (depending on patient presentation) Patient Position: Image receptor resting on mid-thigh and tilted so perpendicular to central ray Pt can hold the image receptor in position for a supine position Angle central ray so it's parallel to the patella and travelling through the joint space AXIAL PATELLA / SKYLINE VIEW: EVALUATION CRITERIA SKYLINE KNEE:  Regional anatomy included – distal femur and patella, including soft tissue  Base and apex of patella superimposed  Femoropatellar joint space open  Patella in profile  Femoral condyles appear symmetrical  Density and contrast optimal to visualise bone & soft tissue KNEE PATHOLOGY Fracture Peri-prosthesis fracture Dislocation  OSTEOARTHRITIS:  Common protocol includes weight-bearing views  Caused by repetitive & mechanical stresses over many decades. Often in people over 50  Presentation includes pain, stiffness and locking joints  OSTEOARTHRITIS:  Obvious visual deformity may include uneven gait and varus or valgus deformity  Radiographic Appearance:  Decreased joint space  Joint margin osteophytes bone spur)  Subchondral (bone below cartilage in a joint) bone sclerosis (pathological hardening)  “LOOSE” BODIES:  Presentation includes pain, catching & joint locking  Caused by trauma or degenerative disease  Usually well demonstrated on intercondylar projection https://radiopaedia.org/articles/intra-articular-loose-bodies-2 VARUS DEFORMITY:  “Bow legged”  Angular deformity of lower legs outwards  Medial joint destruction  Assessed with long leg radiographs https://radiopaedia.org/cases/osteoarthritis-of-the-knee VALGUS DEFORMITY:  “Knock knee”  Angular deformity of the lower legs inwards  Lateral joint destruction  Assessed with long leg radiographs TOTAL KNEE REPLACEMENT (TKR):  Replace articular surfaces of femur, tibia and patella  Complications – instability, bone fracture, infection, loosening of prosthesis Key imaging principle: Always include all of hardware- including cement Long Stem TKR Periprosthetic Fracture FABELLA:  Accessory ossicle in the gastrocnemius muscle  Occurs in 10-30% of the population https://radiopaedia.org/articles/fabella DISLOCATION:  Patellofemoral dislocation = patella becomes dislocated from the groove in the femur  Patellofemoral Subluxation = due to ruptured ligament and the knee will temporarily dislocate and then relocate  Femorotibial (rare) = femur and tibia dislocate  Dislocations can have associated fractures https://radiopaedia.org/articles/knee-dislocation Patella Fracture  Caused by direct force to patella or sudden forceful contraction of the quadriceps tendon  Point tenderness, swelling, large joint effusion  Transverse (most common), communited, pathological fracture Patella Fracture Post ORIF- Tension band wire BIPARTITE & TRIPARTITE PATELLA:  Commonly mistaken for a fracture  Bipartite = 2 part patella  Tripartite = 3 part patella  Congenital condition where there is a fusion failure of the accessory ossification centre https://radiopaedia.org/articles/bipartite-patella  OSGOOD SCHLATTER DISEASE:  Occurs in active children aged 9–16 coinciding with periods of growth.  Boys > Girls  Caused by stress on the tendon  The patella tendon that connects the tibial tuberosity to the patella pulls on the growth plate OSGOOD SCHLATTER DISEASE: MRI KNEE:  MRI is the modality of choice to evaluate soft tissue injury surrounding the knee  Visualises the menisci, the cruciate and collateral ligaments, ACL and PCL REFERENCES:  Bontrager, K. L. (2005) Textbook of Radiographic Positioning and Related Anatomy. (6th edn.) St Louis: Mosby.  Eisenberg, R. L. (2003) Comprehensive Radiographic Pathology (3rd edn.) St Louis: Mosby.  McQuillen-Martensen, K. (1996) Radiographic Critique. Philadelphia : W.B. Saunders.  Weir, J. & Abrahams, S. P. (2003) Imaging Atlas of Human Anatomy (3rd ed). London: Mosby.  http://www.wikiradiography.net  https://radiopaedia.org  https://www.radiologymasterclass.co.uk/