Knee Surgery, Sports Traumatology, Arthroscopy

, Volume 25, Issue 8, pp 2405–2413 | Cite as

Effects of upright weight bearing and the knee flexion angle on patellofemoral indices using magnetic resonance imaging in patients with patellofemoral instability

  • Christoph BecherEmail author
  • Benjamin Fleischer
  • Marten Rase
  • Thees Schumacher
  • Max Ettinger
  • Sven Ostermeier
  • Tomas Smith



This study analysed the effects of upright weight bearing and the knee flexion angle on patellofemoral indices, determined using magnetic resonance imaging (MRI), in patients with patellofemoral instability (PI).


Healthy volunteers (control group, n = 9) and PI patients (PI group, n = 16) were scanned in an open-configuration MRI scanner during upright weight bearing and supine non-weight bearing positions at full extension (0° flexion) and at 15°, 30°, and 45° flexion. Patellofemoral indices included the Insall–Salvati Index, Caton–Deschamp Index, and Patellotrochlear Index (PTI) to determine patellar height and the patellar tilt angle (PTA), bisect offset (BO), and the tibial tubercle–trochlear groove (TT–TG) distance to assess patellar rotation and translation with respect to the femur and alignment of the extensor mechanism.


A significant interaction effect of weight bearing by flexion angle was observed for the PTI, PTA, and BO for subjects with PI. At full extension, post hoc pairwise comparisons revealed a significant effect of weight bearing on the indices, with increased patellar height and increased PTA and BO in the PI group. Except for the BO, no such changes were seen in the control group. Independent of weight bearing, flexing the knee caused the PTA, BO, and TT–TG distance to be significantly reduced.


Upright weight bearing and the knee flexion angle affected patellofemoral MRI indices in PI patients, with significantly increased values at full extension. The observations of this study provide a caution to be considered by professionals when treating PI patients. These patients should be evaluated clinically and radiographically at full extension and various flexion angles in context with quadriceps engagement.

Level of evidence

Explorative case–control study, Level III.


Knee Patellar instability MRI Patellofemoral indices Weight bearing 



The authors thank the staff of the “Privatpraxis für Upright-Kernspintomographie , Hannover” for their help and support during the study. The programme “Hochschulinterne Leistungsförderung (HiLF)” of Hannover Medical School supported this study.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Ali SA, Helmer R, Terk MR (2009) Patella alta: lack of correlation between patellotrochlear cartilage congruence and commonly used patellar height ratios. AJR Am J Roentgenol 193:1361–1366CrossRefPubMedGoogle Scholar
  2. 2.
    Balcarek P, Jung K, Ammon J, Walde TA, Frosch S, Schuttrumpf JP, Sturmer KM, Frosch KH (2010) Anatomy of lateral patellar instability: trochlear dysplasia and tibial tubercle–trochlear groove distance is more pronounced in women who dislocate the patella. Am J Sports Med 38:2320–2327CrossRefPubMedGoogle Scholar
  3. 3.
    Balcarek P, Jung K, Frosch KH, Sturmer KM (2011) Value of the tibial tuberosity–trochlear groove distance in patellar instability in the young athlete. Am J Sports Med 39:1756–1761CrossRefPubMedGoogle Scholar
  4. 4.
    Barnett AJ, Prentice M, Mandalia V, Wakeley CJ, Eldridge JD (2009) Patellar height measurement in trochlear dysplasia. Knee Surg Sports Traumatol Arthrosc 17:1412–1415CrossRefPubMedGoogle Scholar
  5. 5.
    Biedert RM, Albrecht S (2006) The patellotrochlear index: a new index for assessing patellar height. Knee Surg Sports Traumatol Arthrosc 14:707–712CrossRefPubMedGoogle Scholar
  6. 6.
    Brossmann J, Muhle C, Schroder C, Melchert UH, Bull CC, Spielmann RP, Heller M (1993) Patellar tracking patterns during active and passive knee extension: evaluation with motion-triggered cine MR imaging. Radiology 187:205–212CrossRefPubMedGoogle Scholar
  7. 7.
    Camathias C, Pagenstert G, Stutz U, Barg A, Muller-Gerbl M, Nowakowski AM (2015) The effect of knee flexion and rotation on the tibial tuberosity–trochlear groove distance. Knee Surg Sports Traumatol Arthrosc. doi: 10.1007/s00167-015-3508-9 Google Scholar
  8. 8.
    Caton J, Deschamps G, Chambat P, Lerat JL, Dejour H (1982) Patella infera. Apropos of 128 cases. Rev Chir Orthop Reparatrice Appar Mot 68:317–325PubMedGoogle Scholar
  9. 9.
    Charles MD, Haloman S, Chen L, Ward SR, Fithian D, Afra R (2013) Magnetic resonance imaging-based topographical differences between control and recurrent patellofemoral instability patients. Am J Sports Med 41:374–384CrossRefPubMedGoogle Scholar
  10. 10.
    Dejour H, Walch G, Nove-Josserand L, Guier C (1994) Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc 2:19–26CrossRefPubMedGoogle Scholar
  11. 11.
    Dietrich TJ, Betz M, Pfirrmann CW, Koch PP, Fucentese SF (2014) End-stage extension of the knee and its influence on tibial tuberosity–trochlear groove distance (TTTG) in asymptomatic volunteers. Knee Surg Sports Traumatol Arthrosc 22:214–218CrossRefPubMedGoogle Scholar
  12. 12.
    Dornacher D, Reichel H, Lippacher S (2014) Measurement of tibial tuberosity–trochlear groove distance: evaluation of inter- and intraobserver correlation dependent on the severity of trochlear dysplasia. Knee Surg Sports Traumatol Arthrosc 22:2382–2387CrossRefPubMedGoogle Scholar
  13. 13.
    Draper CE, Besier TF, Fredericson M, Santos JM, Beaupre GS, Delp SL, Gold GE (2011) Differences in patellofemoral kinematics between weight-bearing and non-weight-bearing conditions in patients with patellofemoral pain. J Orthop Res 29:312–317CrossRefPubMedGoogle Scholar
  14. 14.
    Draper CE, Besier TF, Santos JM, Jennings F, Fredericson M, Gold GE, Beaupre GS, Delp SL (2009) Using real-time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motion. J Orthop Res 27:571–577CrossRefPubMedPubMedCentralGoogle Scholar
  15. 15.
    Fithian DC, Paxton EW, Stone ML, Silva P, Davis DK, Elias DA, White LM (2004) Epidemiology and natural history of acute patellar dislocation. Am J Sports Med 32:1114–1121CrossRefPubMedGoogle Scholar
  16. 16.
    Fulkerson JP, Schutzer SF, Ramsby GR, Bernstein RA (1987) Computerized tomography of the patellofemoral joint before and after lateral release or realignment. Arthroscopy 3:19–24CrossRefPubMedGoogle Scholar
  17. 17.
    Fulkerson JP, Shea KP (1990) Disorders of patellofemoral alignment. J Bone Joint Surg Am 72:1424–1429CrossRefPubMedGoogle Scholar
  18. 18.
    Fuss FK (1992) Principles and mechanisms of automatic rotation during terminal extension in the human knee joint. J Anat 180(Pt 2):297–304PubMedPubMedCentralGoogle Scholar
  19. 19.
    Hill PF, Vedi V, Williams A, Iwaki H, Pinskerova V, Freeman MA (2000) Tibiofemoral movement 2: the loaded and unloaded living knee studied by MRI. J Bone Joint Surg Br 82:1196–1198CrossRefPubMedGoogle Scholar
  20. 20.
    Ho CP, James EW, Surowiec RK, Gatlin CC, Ellman MB, Cram TR, Dornan GJ, LaPrade RF (2015) Systematic technique-dependent differences in CT versus MRI measurement of the tibial tubercle–trochlear groove distance. Am J Sports Med 43:675–682CrossRefPubMedGoogle Scholar
  21. 21.
    Insall J, Salvati E (1971) Patella position in the normal knee joint. Radiology 101:101–104CrossRefPubMedGoogle Scholar
  22. 22.
    Izadpanah K, Weitzel E, Vicari M, Hennig J, Weigel M, Sudkamp NP, Niemeyer P (2014) Influence of knee flexion angle and weight bearing on the tibial tuberosity–trochlear groove (TTTG) distance for evaluation of patellofemoral alignment. Knee Surg Sports Traumatol Arthrosc 22:2655–2661CrossRefPubMedGoogle Scholar
  23. 23.
    Johal P, Williams A, Wragg P, Hunt D, Gedroyc W (2005) Tibio-femoral movement in the living knee. A study of weight bearing and non-weight bearing knee kinematics using ‘interventional’ MRI. J Biomech 38:269–276CrossRefPubMedGoogle Scholar
  24. 24.
    Kim TH, Sobti A, Lee SH, Lee JS, Oh KJ (2014) The effects of weight-bearing conditions on patellofemoral indices in individuals without and with patellofemoral pain syndrome. Skeletal Radiol 43:157–164CrossRefPubMedGoogle Scholar
  25. 25.
    Miller TT, Staron RB, Feldman F (1996) Patellar height on sagittal MR imaging of the knee. AJR Am J Roentgenol 167:339–341CrossRefPubMedGoogle Scholar
  26. 26.
    Pal S, Besier TF, Beaupre GS, Fredericson M, Delp SL, Gold GE (2013) Patellar maltracking is prevalent among patellofemoral pain subjects with patella alta: an upright, weightbearing MRI study. J Orthop Res 31:448–457CrossRefPubMedGoogle Scholar
  27. 27.
    Pal S, Besier TF, Draper CE, Fredericson M, Gold GE, Beaupre GS, Delp SL (2012) Patellar tilt correlates with vastus lateralis: vastus medialis activation ratio in maltracking patellofemoral pain patients. J Orthop Res 30:927–933CrossRefPubMedGoogle Scholar
  28. 28.
    Pal S, Draper CE, Fredericson M, Gold GE, Delp SL, Beaupre GS, Besier TF (2011) Patellar maltracking correlates with vastus medialis activation delay in patellofemoral pain patients. Am J Sports Med 39:590–598CrossRefPubMedGoogle Scholar
  29. 29.
    Piazza SJ, Cavanagh PR (2000) Measurement of the screw-home motion of the knee is sensitive to errors in axis alignment. J Biomech 33:1029–1034CrossRefPubMedGoogle Scholar
  30. 30.
    Regalado G, Lintula H, Eskelinen M, Kokki H, Kroger H, Svedstrom E, Vahlberg T, Vaatainen U (2014) Dynamic KINE-MRI in patellofemoral instability in adolescents. Knee Surg Sports Traumatol Arthrosc 22:2795–2802CrossRefPubMedGoogle Scholar
  31. 31.
    Schoettle PB, Zanetti M, Seifert B, Pfirrmann CW, Fucentese SF, Romero J (2006) The tibial tuberosity–trochlear groove distance; a comparative study between CT and MRI scanning. Knee 13:26–31CrossRefPubMedGoogle Scholar
  32. 32.
    Seil R, Muller B, Georg T, Kohn D, Rupp S (2000) Reliability and interobserver variability in radiological patellar height ratios. Knee Surg Sports Traumatol Arthrosc 8:231–236CrossRefPubMedGoogle Scholar
  33. 33.
    Seitlinger G, Scheurecker G, Hogler R, Labey L, Innocenti B, Hofmann S (2014) The position of the tibia tubercle in 0 degrees–90 degrees flexion: comparing patients with patella dislocation to healthy volunteers. Knee Surg Sports Traumatol Arthrosc 22:2396–2400CrossRefPubMedGoogle Scholar
  34. 34.
    Shabshin N, Schweitzer ME, Morrison WB, Parker L (2004) MRI criteria for patella alta and baja. Skeletal Radiol 33:445–450CrossRefPubMedGoogle Scholar
  35. 35.
    Souza RB, Draper CE, Fredericson M, Powers CM (2010) Femur rotation and patellofemoral joint kinematics: a weight-bearing magnetic resonance imaging analysis. J Orthop Sports Phys Ther 40:277–285CrossRefPubMedGoogle Scholar
  36. 36.
    Steensen RN, Bentley JC, Trinh TQ, Backes JR, Wiltfong RE (2015) The prevalence and combined prevalences of anatomic factors associated with recurrent patellar dislocation: a magnetic resonance imaging study. Am J Sports Med 43:921–927CrossRefPubMedGoogle Scholar
  37. 37.
    Teng HL, Chen YJ, Powers CM (2014) Predictors of patellar alignment during weight bearing: an examination of patellar height and trochlear geometry. Knee 21:142–146CrossRefPubMedGoogle Scholar
  38. 38.
    Tennant S, Williams A, Vedi V, Kinmont C, Gedroyc W, Hunt DM (2001) Patello-femoral tracking in the weight-bearing knee: a study of asymptomatic volunteers utilising dynamic magnetic resonance imaging: a preliminary report. Knee Surg Sports Traumatol Arthrosc 9:155–162CrossRefPubMedGoogle Scholar
  39. 39.
    Ward SR, Terk MR, Powers CM (2007) Patella alta: association with patellofemoral alignment and changes in contact area during weight-bearing. J Bone Joint Surg Am 89:1749–1755PubMedGoogle Scholar

Copyright information

© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2015

Authors and Affiliations

  • Christoph Becher
    • 1
    Email author
  • Benjamin Fleischer
    • 2
  • Marten Rase
    • 1
  • Thees Schumacher
    • 1
  • Max Ettinger
    • 1
  • Sven Ostermeier
    • 3
  • Tomas Smith
    • 1
  1. 1.Department of Orthopedic SurgeryHannover Medical SchoolHannoverGermany
  2. 2.Department of Biomechanics and BiomaterialsHannover Medical SchoolHannoverGermany
  3. 3.Gelenk-KlinikGundelfingen/FreiburgGermany

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