Anterior Knee Pain By Dr. Brian Sabb


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Award Winning Anterior Knee Pain Educational Exhibit at The American Roentgen Ray Society (ARRS)Annual Meeting

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  • Decrease the lateralization of the patella
  • Anterior Knee Pain By Dr. Brian Sabb

    1. 1. Anterior Knee Pain: A Diagnostic Conundrum Brian Sabb, DO J. David Blaha, MD Department of Orthopaedic Surgery
    2. 2. Disclosure of Commercial Interest <ul><li>Neither I nor my immediate family members have a financial relationship with a commercial organization that may have a direct or indirect interest in the content. </li></ul>
    3. 3. Objectives <ul><li>Improve the participant’s understanding of the radiologic diagnosis of anterior knee pain </li></ul><ul><li>The participant will know specific imaging findings of anterior knee pathology </li></ul><ul><li>Understand the biomechanics and pathophysiology of the patellofemoral joint and how they should be applied to the imaging evaluation </li></ul>
    4. 4. Anterior Knee Pain Anatomical Categorization <ul><li>Prepatellar Soft Tissues </li></ul><ul><li>Quadriceps Fat Pad </li></ul><ul><li>Infrapatellar Fat Pad of Hoffa </li></ul><ul><li>Extensor Mechanism </li></ul><ul><li>Patellofemoral Joint </li></ul><ul><li>Patella </li></ul>
    5. 5. Prepatellar Bursitis <ul><li>Inflammation of the prepatellar bursa </li></ul><ul><li>In more severe cases one will see formation of a discrete fluid collection </li></ul><ul><li>Can become infected, i.e. septic bursitis </li></ul><ul><li>In chronic cases, may contain multiple calcified bodies </li></ul><ul><li>US may show hyperemia; suggesting inflammation, infection, or acute trauma </li></ul>
    6. 6. Prepatellar Bursitis PD PD FAT SAT
    7. 7. Prepatellar Bursitis PD PD FAT SAT T2 FAT SAT
    8. 8. Quadriceps Fat Pad Edema <ul><li>Shown in a recent study to clinically mimic meniscal tear in 55% of patients and to present with anterior knee pain in 28% of patients </li></ul><ul><li>Present in about 4-12 % of knee MRIs </li></ul><ul><li>Edema may be present with or without mass effect </li></ul>Shabshin, Skeletal Radiology. 2006 May; 35(5): 269-74 Roth, AJR. 2004 Jun;182(6):1383-7
    9. 9. Quadriceps Fat Pad Edema PD PD FAT SAT T2 FAT SAT
    10. 10. Infrapatellar Fat Pad of Hoffa <ul><li>Hoffa’s disease </li></ul><ul><li>Localized nodular synovitis </li></ul><ul><li>Pigmented villonodular synovitis (PVNS) </li></ul><ul><li>Intraarticular chondroma </li></ul><ul><li>Infrapatellar plica syndrome </li></ul>
    11. 11. Hoffa’s Disease <ul><li>A syndrome of fat pad impingement </li></ul><ul><li>Acute or repetitive trauma causes inflammatory changes in the infrapatellar fat </li></ul><ul><li>The resulting pain, swelling, and fat hypertrophy limits range of motion </li></ul><ul><li>Over time, fibrotic tissue is formed </li></ul>
    12. 12. Hoffa’s Disease PD PD FAT SAT
    13. 13. Localized Nodular Synovitis <ul><li>Benign proliferative disease </li></ul><ul><li>Most commonly affects the tendon sheaths of the hands, e.g. giant cell tumor of tendon sheath </li></ul><ul><li>MRI demonstrates a well defined mass in Hoffa’s fat pad </li></ul><ul><li>Typically low SI on T1 and variable SI on T2 </li></ul>
    14. 14. Localized Nodular Synovitis PD PD FAT SAT T2 FAT SAT
    15. 15. Pigmented Villonodular Synovitis (PVNS) <ul><li>Benign proliferative disorder of the synovium </li></ul><ul><li>Usually involves large joints </li></ul><ul><li>80% of cases affect the knee </li></ul><ul><li>Synovial deposition of hemosiderin results in irregular synovial masses that show a significant amount of hypointensity on all sequences </li></ul>
    16. 16. Pigmented Villonodular Synovitis (PVNS) PD PD FAT SAT T2 FAT SAT
    17. 17. Intraarticular Chondroma <ul><li>Although a rare lesion; they overwhelmingly occur around the knee, typically the infrapatellar fat pad </li></ul><ul><li>May calcify and even ossify </li></ul><ul><li>May erode the lower pole of the patella </li></ul><ul><li>May displace the patellar tendon </li></ul>
    18. 18. Intraarticular Chondroma PD PD FAT SAT T2 FAT SAT
    19. 19. Infrapatellar Plica Injury <ul><li>A thin fold of synovial tissue, extending from the inferior pole of the patella through Hoffa’s fat to the intercondylar notch anterior to the anterior cruciate ligament </li></ul><ul><li>High signal along the course of the plica indicates injury to the plica </li></ul><ul><li>Thickening of the plica even in the absence of edema or fluid suggests a chronic injury </li></ul>Cothran, AJR 2003; 180(5): 1443-1447
    20. 20. Infrapatellar Plica Injury PD PD FAT SAT T2 FAT SAT
    21. 21. Extensor Mechanism Pathology <ul><li>Traumatic </li></ul><ul><ul><li>Tendinosis </li></ul></ul><ul><ul><li>Patellar tendon tear </li></ul></ul><ul><ul><li>Quadriceps tendon tear </li></ul></ul><ul><li>Intrinsic patellar tendon lesions, e.g. gout </li></ul><ul><li>Patellar enthesopathy </li></ul><ul><li>Osteochondroses, e.g. Osgood-Schlatter Disease </li></ul>
    22. 22. Patellar Tendinosis <ul><li>Pain in the infrapatellar region </li></ul><ul><li>Commonly seen in athletes </li></ul><ul><li>MRI demonstrates thickening of the patellar tendon with intermediate T1 or PD signal and increased signal on T2 especially with fat suppression </li></ul><ul><li>Ultrasound demonstrates thickening, hypoechogenicity, and increased color flow </li></ul>
    23. 23. Patellar Tendinosis PD PD FAT SAT T2 FAT SAT
    24. 24. Patellar Tendon Tear <ul><li>MRI </li></ul><ul><ul><li>Fluid signal is seen at site of tear; decreased T1 and increased T2 signal </li></ul></ul><ul><ul><li>A tendon gap is seen along with diastasis of tendon fibers in full thickness tear </li></ul></ul><ul><li>US </li></ul><ul><ul><li>Hypoechoic foci </li></ul></ul><ul><ul><li>Posterior shadowing is seen at ends of the retracted tendon in full thickness tear </li></ul></ul><ul><ul><li>Patella alta </li></ul></ul>
    25. 25. Complete Patellar Tendon Tear PD FAT SAT Longitudinal Ultrasound
    26. 26. Quadriceps Tendon Tear <ul><li>MRI </li></ul><ul><ul><li>Partial thickness tear reveals small pockets of fluid indicating tear often superimposed on the more diffuse increased T2 signal of tendinosis </li></ul></ul><ul><li>Ultrasound </li></ul><ul><ul><li>Partial thickness tears demonstrate hypoechogenicity and swelling </li></ul></ul><ul><li>By both modalities, tendon retraction and discontinuity of fibers indicates full thickness tear </li></ul>
    27. 27. Quadriceps Tendon Tear Full thickness tear by MR with diastasis of fibers filled by high T2 fluid and and by longitudinal US with hypoechoic fluid PD FAT SAT
    28. 28. PD FAT SAT Complete Quadriceps Tendon Tear PD Note: patella baja
    29. 29. Intrinsic Patellar Tendon Lesion: Gout <ul><li>MRI reveals low T1 and mildly high T2 signal. There is an infiltrating mass present </li></ul><ul><li>Ultrasound reveals hyperechogenicity, acoustic shadowing, and calcifications. Employing color flow imaging is important since peripheral hyperemia is expected </li></ul>
    30. 30. Gout of The Patellar Tendon PD PD FAT SAT T2 FAT SAT T2 FAT SAT T2 FAT SAT
    31. 31. Gout of The Patellar Tendon by US Intratendinous Crystals Peripheral hyperemia Shadowing
    32. 32. Enthesopathy of The Patella <ul><li>May be related to a degenerative process </li></ul><ul><li>One must also consider inflammatory arthropathies </li></ul><ul><ul><li>Psoriasis </li></ul></ul><ul><ul><li>Ankylosing spondylitis </li></ul></ul><ul><ul><li>Reactive arthritis </li></ul></ul>
    33. 33. Psoriasis PD PD FAT SAT PD FAT SAT
    34. 34. Ankylosing Spondylitis
    35. 35. Ankylosing Spondylitis PD PD FAT SAT T2 FAT SAT T1 Extensive bone marrow edema and associated enthesitis
    36. 36. Reactive Arthritis
    37. 37. Osgood Schlatter Disease <ul><li>An osteochondrosis of the tibial tubercle manifesting as anterior knee pain in adolescents </li></ul><ul><li>The fragmentation can persist into adulthood and cause continued or recurrent symptoms </li></ul>
    38. 38. Sequela of Osgood Schlatter PD PD FAT SAT T2 FAT SAT T1 Note the irregularity and edema causing recurrent and chronic pain
    39. 39. Patellar Malalignment <ul><li>Transient Patellar Dislocation </li></ul><ul><li>Excessive Lateral Pressure Syndrome (ELPS) </li></ul><ul><li>Patellar Tendon Lateral Femoral Condyle Friction Syndrome </li></ul>
    40. 40. Transient Patellar Dislocation <ul><li>The medial patellar facet impacts against the lateral femoral condyle, producing bone bruises or microfractures. The pattern is nearly pathognomonic </li></ul><ul><li>Injury to the medial patellar retinaculum is very common </li></ul><ul><li>Predisposing factors include dysplastic trochlea, patella alta, lateralized tibial tubercle, and tight lateral retinaculum </li></ul><ul><li>Treatment for recurrent dislocation often includes lateral retinacular release to decrease lateralization force on the patella </li></ul>
    41. 41. Transient Patellar Dislocation Lateral femoral condyle T2 FAT SAT Medial patella
    42. 42. Excessive Lateral Pressure Syndrome (ELPS) <ul><li>Classically categorized as tilt without subluxation. Look for narrowing at the lateral aspect of the patellofemoral joint, especially in young patients with anterior knee pain </li></ul><ul><li>However, only rarely see advanced tilt without subluxation </li></ul><ul><li>Surgical treatment includes lateral retinacular release to decrease the translational force on the patella </li></ul><ul><li>Attempt to make the diagnosis before advanced osteoarthritis (OA) ensues </li></ul>
    43. 43. January 2001 at 27 years old August 2005 at 31 years old Excessive Lateral Pressure Syndrome T2 FAT SAT T2 FAT SAT The OA renders treatment/surgery less effective Suggest the diagnosis based on the tilt; prior to OA Images courtesy of Mark Schweitzer, MD
    44. 44. Patellar Tendon-Lateral Femoral Condyle Friction Syndrome <ul><li>Presents as anterior knee pain exacerbated by hyperextension </li></ul><ul><li>MRI reveals edema in the superolateral aspect of Hoffa’s fat pad between the patellar tendon and the lateral femoral condyle </li></ul><ul><li>Likely related to, or a form of patellar malalignment </li></ul><ul><li>Associated with patella alta </li></ul>Chung, Skeletal Radiology 2001 Nov; 39: 694-697
    45. 45. Patellar Tendon Lateral Femoral Condyle Friction Syndrome PD FAT SAT Cor FAT SAT T2 FAT SAT The alta allows for the contact between the tendon and the femoral condyle
    46. 46. Patellar Abnormalities <ul><li>Bipartite patella </li></ul><ul><li>Multipartite patella </li></ul><ul><li>Patellar fracture </li></ul>
    47. 47. Bipartite Patella <ul><li>Painful bipartite patella is a cause of anterior knee pain </li></ul><ul><li>Any bipartite or multipartite bone can develop a pseudarthrosis </li></ul><ul><li>The pseudarthrosis is manifested on MRI as bone marrow edema and as fluid between the osseous fragments </li></ul><ul><li>Initial treatment includes physical therapy, rest, and pain control </li></ul><ul><li>When initial therapy fails, surgery is often performed </li></ul><ul><li>Surgical options include: </li></ul><ul><ul><li>Resection of the painful fragment </li></ul></ul><ul><ul><li>Lateral retinacular release </li></ul></ul><ul><ul><li>Detachment of the insertion site of the vastus lateralis </li></ul></ul>
    48. 48. Bipartite Patella PD FAT SAT T2 FAT SAT Cor T2 FAT SAT Note the accessory ossicle is typically superolateral Bone marrow edema and cystic changes correlate with pain Cor T1
    49. 49. Multipartite Patella T2 FAT SAT Cor T2 FAT SAT Cor T2 FAT SAT T1 Note the typical superolateral fragments
    50. 50. Patellar Fracture <ul><li>Susceptible to fracture because of its superficial location and lack of protection </li></ul><ul><li>Two-thirds are horizontal fractures </li></ul><ul><li>Next most frequent are comminuted and vertical fractures </li></ul><ul><li>Look for sharp fracture lines, joint effusion, and location of fracture lines away from the typical superolateral location of an accessory ossicle </li></ul>
    51. 51. Patellar Fracture
    52. 52. Patellar Fracture Axial CT showing a lipohemarthrosis
    53. 53. Corresponding Author: Brian Sabb [email_address]