Patella position in the trochlea groove: comparison between supine and standing radiographs

Transcription

1 Patella position in the trochlea groove: comparison between supine and standing radiographs Award: Winner Poster No.: P-0098 Congress: ESSR 2014 Type: Authors: Keywords: DOI: Scientific Poster N. Skou, N. Egund; Aarhus C/DK Extremities, Conventional radiography, Technical aspects, Arthritides /essr2014/P-0098 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 11

2 Purpose Patellofemoral (PF) pain syndrome is thought to be associated with mechanical factors. Neither computed tomography (CT) nor magnetic resonance imaging (MRI) has contributed significantly to determine the causal pathway or treatment (1,2). Based on clinical examination and imaging in the supine position, patellar maltracking with lateral displacement is still believed a leading cause of PF pain (3-7). Axial radiographs of the PF joint in the supine position have demonstrated lateral PF osteoarthritis (OA) more commonly than medial PF OA (8). However, medial PF OA appears to be as prevalent as lateral OA by standing axial radiographs of the PF joint and in large studies using MRI (9,10). The purpose of this study was to compare patellar position in the trochlea groove and to assess the detection of medial and lateral PF joint space narrowing on axial radiographs in both supine and standing position. Methods and Materials The study sample comprised 36 females and 23 males with a mean/median age of 56/57 years (18-87 years). Six patients obtained examination of one knee only, resulting in a total of 112 knees. Standing weightbearing axial radiographs of the PF joint in 30 knee flexion with weightbearing on one leg were obtained using a support device that kept the lower leg in 15 inclination (11) (Fig. 1). Axial views of the PF joint in the supine position were obtained according to Laurin et al. (12) in 30 knee flexion (Fig. 2). The following workstation measurements on supine and standing axial PF radiographs were made: differences in patellar tilt, medial/lateral patellar displacement and differences in medial and lateral joint space width (Fig. 3). The grade of medial/lateral PF OA according to Ahlbäck (13) was also assessed. Inter- and intra-reader agreement analyses were performed. Images for this section: Page 2 of 11

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4 Fig. 1: Patient position for the axial standing radiographic view of the right patellofemoral (PF) joint. The inclination of the lower leg at 15 is secured by a device supporting the knee and lower leg. In this position most tibial plateaus and patellar articular surfaces are in alignment with horizontal (11) and vertical beam directions (thick white arrow), respectively and the CR detector plate (C) is placed corresponding to the central beam. Note that weightbearing is primarily on the right leg using the left leg for slight support only. The weightbearing axis from the hip is dorsal to the ankle (thin white arrow). Fig. 2: The axial radiographic view of the PF joint in the supine position according to Laurin et al. The angle between the central beam (white line) and the ventral aspect of the lower leg should optimally be less than 15 and the film cassette or CR detector plate (C) perpendicular to the central beam. Page 4 of 11

5 Fig. 3: Axial radiographic views of the right and left normal PF joint obtained in supine (A and B) and standing position (C and D) in a 45-year-old male. The recorded measures are the differences between angles or distances from supine to standing radiographs. Patellar tilt is the angle between the baseline (arrow) joining the ventral aspects of the femoral condyles and a line (arrowhead) between the medial and lateral part of the patella (A and C). The medial and lateral landmarks defining the patellar line (arrowhead) are bone structures recognizable on both radiographs of the same knee e.g. osteophytes. Measurement of patella displacement (B and D). A line perpendicular to the baseline (arrow) originating from recognizable points on the medial femoral condyle is constructed and the distance to the medial aspect of the patella is measured. Measurements of medial and lateral joint space width (JSW) are indicated by the lines in the joint space (A and C). Page 5 of 11

6 Results Medial PF OA increased or appeared in 16 joints from supine to standing (Table 1) (Figs. 4, 5). The grades of lateral PF OA were almost unchanged from the supine to the standing position (Table 2). From supine to standing position the patellar tilt decreased, the patella moved medially and the medial joint space width decreased (Table 2) (Fig. 3). The differences were significant (p < ) for all 3 measured parameters. Less than 15% did not change position or moved in the opposite direction (Table 2). The width of lateral PF joint space was almost unchanged (p = 0.3 and p = 0.1, right and left side, respectively). Also in joints with lateral PF OA, the patella was displaced medially from the supine to the standing position (Fig. 6). Intra- and interreader agreement: Altman Bland test showed a bias # 0.14 for all pairs of measurements. The 95% limits of agreement were # -1.6/1.8 mm for measurements of difference of joint space width and displacement and # -2.2/2.10 for the difference in patellar tilt. Images for this section: Table 1: The number of knees with medial and lateral PF joint space (JS) narrowings according to Ahlbäck (13) on supine and standing axial radiographs. Grade 1 = JS narrowing, grade 2 = obliteration of the JS and grade 3 = bone attrition < 5 millimeters. Page 6 of 11

7 Fig. 4: Supine (A) and standing (B) axial radiographs of the PF joint in a 41-year-old female. The joint spaces are normal in the supine position (A). In the standing position there is a medial tilt and displacement of the patella and obliteration of the medial PF joint space. Fig. 5: Supine (A) and standing (B) axial radiographs of the PF joint in a 62-year-old female. (A) shows widening of the medial joint space in the supine position. In the standing position there is a medial tilt, displacement of the patella and a reduced medial PF joint space, Ahlbäck grade 1 (B). Table 2: The difference in the measurements on supine and standing radiographs. The figures represent the calculated reduction of medial joint space width, medial patellar Page 7 of 11

8 displacement and reduction of the patellar tilt angle. Eleven/twelve percent of the knees showed opposing direction of change in position with negative differences. Fig. 3: Axial radiographic views of the right and left normal PF joint obtained in supine (A and B) and standing position (C and D) in a 45-year-old male. The recorded measures are the differences between angles or distances from supine to standing radiographs. Patellar tilt is the angle between the baseline (arrow) joining the ventral aspects of the femoral condyles and a line (arrowhead) between the medial and lateral part of the patella (A and C). The medial and lateral landmarks defining the patellar line (arrowhead) are bone structures recognizable on both radiographs of the same knee e.g. osteophytes. Measurement of patella displacement (B and D). A line perpendicular to the baseline (arrow) originating from recognizable points on the medial femoral condyle is constructed and the distance to the medial aspect of the patella is measured. Measurements of medial and lateral joint space width (JSW) are indicated by the lines in the joint space (A and C). Page 8 of 11

9 Fig. 6: Supine (A) and standing (B) axial radiographs of the PF joint in a 69-year-old female. The lateral joint space is almost obliterated (Ahlbäck grade 2) and without change between supine (A) and standing (B). There is a medial tilt and displacement of the patella from the supine (A) to the standing (B) radiograph. Page 9 of 11

10 Conclusion Medial PF joint space narrowing/oa cannot be visualized by axial PF radiographs obtained in supine position. Medial PF joint space narrowing can commonly be visualized by axial PF radiographs obtained in the weightbearing position. Medial patellar tilt and displacement relative to the femoral trochlea on axial PF radiographs may be an obligatory biomechanical effect of weightbearing. The present technique for standing axial radiographs rarely allows weightbearing with both the hip and the ankle aligned vertically. The standing weightbearing position may be of crucial importance for the patellar position in the trochlear groove and for the visualization of medial PF OA. References 1. Insall J. Foreword in: In: Scuderi G, editor. The Patella+ Berlin Heidelberg New York: Springer; Powers CM, Bolgla LA, Callaghan MJ, Collins N, Sheehan FT. Patellofemoral pain: proximal, distal, and local factors, 2nd International Research Retreat. J Orthop Sports Phys Ther 2012;42(6):A Murray TF, Dupont JY, Fulkerson JP. Axial and lateral radiographs in evaluating patellofemoral malalignment. Am J Sports Med 1999;27(5): Schutzer SF, Ramsby GR, Fulkerson JP. Computed tomographic classification of patellofemoral pain patients. Orthop Clin North Am 1986;17(2): Arendt EA, Dejour D. Patella instability: building bridges across the ocean a historic review. Knee Surg Sports Traumatol Arthrosc 2013;21(2): Fulkerson JP, Shea KP. Disorders of patellofemoral alignment. J Bone Joint Surg Am 1990;72(9): Grelsamer RP, Weinstein CH, Gould J, Dubey A. Patellar tilt: the physical examination correlates with MR imaging. Knee 2008;15(1): Iwano T, Kurosawa H, Tokuyama H, Hoshikawa Y. Roentgenographic and clinical findings of patellofemoral osteoarthrosis. With special reference to its relationship to femorotibial osteoarthrosis and etiologic factors. Clin Orthop Relat Res 1990;(252)(252): Gross KD, Niu J, Stefanik JJ, Guermazi A, Roemer FW, Sharma L, et al. Breaking the Law of Valgus: the surprising and unexplained Page 10 of 11

11 prevalence of medial patellofemoral cartilage damage. Ann Rheum Dis 2012;71(11): Rytter S, Egund N, Jensen LK, Bonde JP. Occupational kneeling and radiographic tibiofemoral and patellofemoral osteoarthritis. J Occup Med Toxicol 2009;4: Egund N, Ryd L. Patellar and Quadriceps Mechanism. In: Davies AM, Cassar-Pullicino VN, editors. Imaging of the Knee: Techniques and Applications: Springer-Verlag Berlin Heidelberg; p Laurin CA, Dussault R, Levesque HP. The tangential x-ray investigation of the patellofemoral joint: x-ray technique, diagnostic criteria and their interpretation. Clin Orthop Relat Res 1979;(144)(144): Ahlback S. Osteoarthrosis of the knee. A radiographic investigation. Acta Radiol Diagn (Stockh) 1968:Suppl 277:7-72. Personal Information Skou, Nikolaj; Egund, Niels Department of Radiology Aarhus University Hospital Denmark Correspondence: nikolaj.skou@auh.rm.dk Page 11 of 11