And...WHAT DO WE KNOW ABOUT THE EXCESSIVE LATERAL PRESSURE SYNDROME?

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1 And...WHAT DO WE KNOW ABOUT THE EXCESSIVE LATERAL PRESSURE SYNDROME? Poster No.: C-1107 Congress: ECR 2011 Type: Scientific Exhibit Authors: E. Yllera Contreras, C. Jimenez Zapater, J. Arnaiz García, A. Salvador, T. Piedra Velasco, A. García Bolado, A Canga Villegas, R. GARCIA BARREDO ; Santander/ES, 2 SANTANDER/ES Keywords: Trauma, Inflammation, Athletic injuries, Diagnostic procedure, MR, Musculoskeletal system DOI: /ecr2011/C-1107 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 22

2 Purpose The aim of this work is to review the "excessive lateral pressure syndrome" and analyze the knee anatomy and other patient's characteristics of a serie of patients presenting with focal inflamation in superior lateral Hoffa's pad, in order to identify key anatomical characteristics that can help us to understand the pathomechanics of this entity, and support the final diagnosis. Methods and Materials We present a retrospective review of sixty-three patients. (November,2007August,2010). All of this patients presented a focal increase of signal intensity in T2 weighted images at the superior lateral Hoffa fat pad (Figure 1) on page 4. All of them consulted for knee pain, more probable patellofemoral pain. They were firstly evaluated by an orthopaedic physician. All patients referred knee pain. MR study was required, because the knee examination tests were not conclusive. MR examination was performed in order to clarify their symptoms. We used either a 1.5 T MR (General Electric), or a 3T MR (Philips). We used the standard knee protocol: Saggital T1-weighted images,axial and coronal T2-weighted fat-suppressed images, and saggital fat-suppressed proton density images. There was not intravenous contrast administration in none of them. We analyzed the global knee anatomy, analyzing other different causes of patellofemoral pain. We analized the age, sex, extension of hoffa pad inflammation, and different knee anatomy indexes. In order to assess patellofemoral alignment, we analyzed the index of Insall and Salvati, the congruence angle, the sulcus angle, the Page 2 of 22

3 Index of Insall and Salvati:(Figure 2) on page 4. This index can best be determined in lateral radiograph, with the knee flexed 30º. We analyzed it in the saggital fatsuprressed proton density images. It studies the relationship between the length of patellar tendon and the diagonal length of patella. It must be the same size. Variations more than 20% are considered abnormal.ratio values greater that 1.2 are considered as patella alta(figure 2B) on page. Sulcus angle: (Figure 3) on page 5. It is measured at the most superior slice where the femoral cartilage could be clearly defined on the anterior surface of the femur. o Pathological sulcus angle is considered > 145 Congruence angle: (Figure 4) on page 6. It is also called Merchant angle. The angle of congruence is an index of subluxation but does not assess tilt; congruence angle defines relationship of apex of patella to bisected femoral trochlea. - technique for measurement:the sulcus angle establishes a zero reference line. A second line is projected from the apex of sulcus angle to lowest point of the articular ridge of the patella. If congruence angle it is lateral to congruence line, then angle is positive. If congruence angle it is medial to congruence line, then angle is negative. Normal angle is defined as o < Patellar tilt angle: (Figure 5) on page 9Patellar tilt is present if a line drawn along the o lateral patellar facet and a line drawn along the posterior femoral condyles is less than 7. Tibial tuberosity-trochlear groove distance (TTTG): TTTG is measured between the most anterior point of the tibial tuberosity (Figure 6) on page 8 and the deepest bony point of the trochlear groove, perpendicular to the tangent to the bony borders of the posterior condyles (Figure 7) on page 9. Normal value is considered 13mm (7-17 mm.normal range) Patella morphology evaluation (dysplasia patellae): The subchondral wiberg angle splits the morphology of the patella into three types. Wiberg's classification: Wiberg I: equal size of medial and lateral patellae faces (Figure 8) on page 10. Wiberg II: medial patellae face slighty less than the lateral, and it is Page 3 of 22

4 also plane or slighty convex from the other face. Wiberg III: medial patellae face much smaller than the lateral (Figure 9) on page 11. Hoffa's fat pad inflammation area: 2 We measure the maximum area (mm )in the axial plane with the largest signal T2 hiperintensity (Figure10) on page 12. Images for this section: Fig. 1: Axial T2-weighted fat-sat image, shows a supero-external high signal area, consistent with an excessive lateral pressure syndrome. Page 4 of 22

5 Fig. 2: Insall-Salvatti Index (ISI). A ratio between the length of the patellar tendon (TL) and the maximum vertical length of the patella (PL). Page 5 of 22

6 Fig. 3: Sulcus angle. Page 6 of 22

7 Fig. 4: Congruence angle. Page 7 of 22

8 Fig. 5: Patelar tilt angle. Page 8 of 22

9 Fig. 6: Tibial tuberosity-trochlear groove distance (TTTG). Page 9 of 22

10 Fig. 7: Tibial tuberosity-trochlear groove distance (TTTG). Page 10 of 22

11 Fig. 8: Patella morphology evaluation (dysplasia patellae). Page 11 of 22

12 Fig. 9: Patella morphology evaluation (dysplasia patellae). Page 12 of 22

13 Fig. 10: Hoffa's fat pad inflammation area. Page 13 of 22

14 Results Demographics parameters: Medium age was 38.5(±14.2) years. 7 patients were younger than 30-year-old, and only one was over 60year-old. Bilateral: 12% Anatomy indexes: Medium Istall and Salvatti ratio of1.42±0.17.(pathological>1.2). o o) Medium Congruence angle: 8.4±22.(Pathological > o o Medium Sulcus angle:138.7±9.4. (Pathological > 145 ) 2 Medium Hoffa pad inflamation area: 85.1±60mm. o o Medium Trochlear tilt angle:10.6±7.5.(pathological <7 ) Medium Tibial tuberosity-trochlear groove distance (TTTG): 7.5±5mm. Normal value is considered 13mm (7-17 mm.normal range) Other associated findings: Dysplasia patellae: Wiberg type 3 patella was found in 38%.(frequence in asyntomatic population 19%) Other associated pathology: Torn ligaments 6.3%; meniscus pathology 38%; trabecular microfractures 6.3%. Page 14 of 22

15 Chondromalacia was found in 66% of patients; in whom 25%presented with chondromalacia III and 15% patients with chondromalacia IV. Images for this section: Fig. 1: Axial T2-weighted image. It shows a hyperintense area at the supero-external angle. Page 15 of 22

16 Fig. 2: Axial T2 weighted fat-saturation image. Extensive high signal area at the superoexternal angle of the knee. These findings are compatible with an excesive lateral pressure syndrome. Page 16 of 22

17 Fig. 3: Axial T2-weighted fat-sat image. Excessive lateral pressure syndrome (high signal intensity in the supero-external aspect of the Hoffa fat) Page 17 of 22

18 Page 18 of 22

19 Fig. 4: Sagittal, T1-weighted image showing a patella alta. Fig. 5: Axial T2-weighted fat-sat image, shows a supero-external high signal area, consistent with an excessive lateral pressure syndrome. Page 19 of 22

20 Conclusion Despite the apparent lack of recognition of the imaging findings in literature of the excessive lateral pressure syndrome, it appears to be a clinically well-recognized syndrome. MR imaging allows identification of changes that may be related to the excessive lateral pressure syndrome (also known as patellar tendon-lateral femoral condyle friction syndrome) and that should be distinguished from other causes of anterior or lateral knee pain. MR imaging findings consists on T2 hyperintensity on the superior-lateral hoffa fat pad. Patellar tendon signal hyperintensisty and patellar chondromalacia can also be found. This syndrome is due to Hoffa fat impingement because of lateral femoral condyle friction resulting in inflamatory changes of the interposed fat. All these patients refer an importan pain and difficulty to walk. This process is amenable to conservative therapy, which consists of taping the superior pole of the patella. Though the kinematic studies proved inconclusive, both the associated imaging findings in our serie and the established method of treatment point to abnormalities in patellar tracking or alignment as a possible cause. We have found a clear relation to an Istall and Salvatti ratio greater than 1.2 (patella alta) (1.42±0.17), condition that allows an excessive lateral motion of the patella. A clearly o pathological congruence angle (8.4±22 ) it is also found in our serie. This finding indicates patellar overpressure over lateral condyle. No pathological patellar tilt angle or sulcus angle is found. On the other hand the TTTG distance is in the lower limit of normality, finding that can suggest an alignment disorder that can create excessive tension or force that can lead to overpressure over lateral condyle. In addition a higer share of patients with patellar dysplasia(weiberg 3) is found. The imaging findings suggests an imbalance in the stabilizing structures of the patellofemoral joint, which may support the hypothesis that this entity is caused by Page 20 of 22

21 abnormalities in patellofemoral tracking. A combination of patella alta, Patellar dysplasia, pathological congruence angle and TTTG support the diagnosis. In conclusion, we can emphasize the importance of MR imaging in the evaluation of patients with femoropatellar arthalgia. This entity is a relatively common pathology that affects young adults, bilaterally in 12% of cases, and that is associated to a lateral deviated congruence angle, patella alta, patellar dysplasia and a short TTTG. We must know all these changes in order to differenciate this entity from other causes of patellofemoral pain and Hoffa fat pad inflammation, in order to assess accurately the knee joint. References Patellar tendon-lateral femoral condyle frictionsyndrome: MR imaging in 41patients. Skeletal Radiol (2001). Christie B. Chung, Abdalla Skaff, Bernard Rojer, Juliana Campos, Xavier Stump and Donald Resnik. Detection and staging of chondromalacia patellae: Relative eficacies of conventional MR Imaging, MR Arthrography, and CT Arthrography. AJR 1994; 163: Joseph A. Gagliardi, Ellen M. Chung, Vijay P. Chandnani, Kimberly L. Kesling, Kevin P. Christensen, Robert N. Null, Martin G. radvany, Mark. F. Hansen. Patella malalignment syndrome: rationale to reduce excessive lateral pressure. J Orthop Sports Phys Ther. 1986; 8 (6): Kramer PG. Excessive lateral pressure as a cause of patello-femoral pain syndrome. J R Nav Med Serv Summer; 71 (2): Osborne AH, FarquharsonRoberts MA. Primary recurrent medial subdislocation of both patellae. Long-term review of an exceptional case of miserably malalignment syndrome. An Sist Sanit Navar Sept-Dec; 30 (3): Spanish. García-Mata S, HidalgoOvejero A. Imaging of patellofemoral disorders. Clin Radiol Jul; 59 (7): Review. Elias DA, White LM. nd Principles and practice, vol 2, 2 ed. Samdes, De Lee JC, Drez D In: Orthopaedic sports medicine. Development and clinical application of kinematic MRI of the patellofemoral joint using an extremity MR system. Med Sci Sports Exerc Jun; 31 (6): Shellock FG, Stone KR, Crues JV. MRI Web Clinic - September 2008, Patellar Fat Pad Abnormalities by Gary A. Howell, M.D. Page 21 of 22

22 10. Patellofemoral evaluation with radiographs and computed tomography scans in 60 knees of asymptomatic subjects. Arthroscopy Feb; 23 (2) : Alemparte J, Ekdahl M, Burnier L, Hernández R, Cardemil, Cielo R, Danilla S. 11. Correlating Anatomy and Congruence of the Patellofemoral Joint With Cartilage Lesions. ORTHOPEDICS January 2009;32(1):20. Bin Yang, PhD; Hongbo Tan, PhD; Lui Yang, MD; Gang Dai, PhD; Botao Guo, PhD. Personal Information Page 22 of 22