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Anatomic patellar instability risk factors in primary lateral patellar dislocations do not predict injury patterns: an MRI-based study

  • Knee
  • Published:
Knee Surgery, Sports Traumatology, Arthroscopy Aims and scope

Abstract

Purpose

The primary goal was to describe the injury patterns in a population of primary (first time) lateral patellar dislocators (LPD) to lend clarity to commonly held notions about injury patterns in this population.

Methods

A prospective study identifying patients presenting with LPD between 2008 and 2012. Inclusion criteria were a history and physical exam consistent with primary LPD, and an MRI consistent with the diagnosis without other significant ligamentous injury. On MRI, location of cartilage, medial patellofemoral ligament (MPFL) injury, and bone bruising were noted. Severity was categorized as partial or complete for MPFL and cartilage lesions. Anatomic patellar instability risk factors (patella alta, trochlear dysplasia, increased TT-TG, and lateral patella tilt) were recorded and compared to the injury patterns.

Results

This study involved 157 patients; 107 patients were skeletally mature. Of the 157 patients, 26 had surgery for this injury due to clinician-perceived need for cartilage debridement. MPFL injury severity was complete rupture (N = 69, 44%), partial (N = 67, 43%), and none (N = 19, 13%). MPFL injury location was isolated femoral (N = 16, 10%), isolated patella (N = 26, 17%), isolated mid-substance (0%), multiple locations (N = 95, 61%), and none (N = 20, 13%). Chondral injury location was patella (N = 67, 43%), lateral femoral condyle (N = 11, 7%), multiple locations (N = 53, 34%), and none (N = 26, 17%). A majority (61%) of patellar chondral lesions were at its inferomedial aspect; all medial patellar retinacular partial injuries involved the inferomedial aspect of the patella, consistent with the insertion of the medial patellotibial ligament (MPTL). Skeletally immature patients had a greater risk of isolated patellar MPFL and chondral injury. No clear relationship was found between/across the location and/or severity of bone bruising, MPFL, or chondral injury.

Clinical relevance

Underlying anatomic patellar instability risk factors defined by MRI, do not predict injury patterns. MPFL and chondral injury, as well as bone bruising, are common following LPD. The medial patellotibial ligament is torn in patellar-based medial retinacular injuries, based on MRI injury location. Skeletal immaturity plays a role in the location of the injury pattern with isolated patellar-based MPFL/chondral injury being more common in the skeletally immature patient. Sex does not appear to be a factor in injury patterns after primary LPD. Knowledge of these injury trends will help focus the clinician in injury evaluation when managing primary patellar dislocations.

Level of evidence

Case series, Level IV.

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References

  1. Arai Y, Nakagawa S, Higuchi T, Inoue A, Honjo K, Inoue H, Ikoma K, Ueshima K, Ikeda T, Fujiwara H, Kubo T (2015) Comparative analysis of medial patellofemoral ligament length change pattern in patients with patellar dislocation using open-MRI. Knee Surg Sports Traumatol Arthrosc. doi:10.1007/s00167-015-3689-2

    PubMed Central  Google Scholar 

  2. Arendt EA, England K, Agel J, Tompkins MA (2016) An analysis of knee anatomic imaging factors associated with primary lateral patellar dislocations. Knee Surg Sports Traumatol Arthrosc. doi:10.1007/s00167-016-4117-y

    Google Scholar 

  3. Askenberger M, Arendt EA, Ekstrom W, Voss U, Finnbogason T, Janarv P-M (2016) Medial patellofemoral ligament injuries in children with first-time lateral patellar dislocations: a magnetic resonance imaging and arthroscopic study. Am J Sports Med 44(1):152–158

    Article  PubMed  Google Scholar 

  4. Askenberger M, Janarv P-M, Finnbogason T, Arendt EA (2017) Morphology and anatomic patellar instability risk factors in first-time traumatic lateral patellar dislocations. Am J Sports Med 45(1):50–58

    Article  PubMed  Google Scholar 

  5. Atkin DM, Fithian DC, Marangi KS, Stone ML, Dobson BE, Mendelsohn C (2000) Characteristics of patients with primary acute lateral patellar dislocation and their recovery within the first 6 months of injury. Am J Sports Med 28(4):472–479

    Article  CAS  PubMed  Google Scholar 

  6. Balcarek P, Ammon J, Frosch S, Walde TA, Schuttrumpf JP, Ferlemann KG, Lill H, Sturmer KM, Frosch K-H (2010) Magnetic resonance imaging characteristics of the medial patellofemoral ligament lesion in acute lateral patellar dislocations considering trochlear dysplasia, patella alta, and tibial tuberosity-trochlear groove distance. Arthroscopy 26(7):926–935

    Article  PubMed  Google Scholar 

  7. Balcarek P, Terwey A, Jung K, Walde TA, Frosch S, Schuttrumpf JP, Wachowski MM, Dathe H, Sturmer KM (2013) Influence of tibial slope asymmetry on femoral rotation in patients with lateral patellar instability. Knee Surg Sports Traumatol Arthrosc 21(9):2155–2163

    Article  PubMed  Google Scholar 

  8. Balcarek P, Walde TA, Frosch S, Schuttrumpf JP, Wachowski MM, Sturmer KM, Frosch K-H (2011) Patellar dislocations in children, adolescents and adults: a comparative MRI study of medial patellofemoral ligament injury patterns and trochlear groove anatomy. Eur J Radiol 79(3):415–420

    Article  PubMed  Google Scholar 

  9. Boden BP, Pearsall AW, Garrett WE Jr, Feagin JA Jr (1997) Patellofemoral instability: evaluation and management. J Am Acad Orthop Surg 5(1):47–57

    Article  CAS  PubMed  Google Scholar 

  10. Camanho GL, Viegas AdC, Bitar AC, Demange MK, Hernandez AJ (2009) Conservative versus surgical treatment for repair of the medial patellofemoral ligament in acute dislocations of the patella. Arthroscopy 25(6):620–625

    Article  PubMed  Google Scholar 

  11. Christiansen SE, Jakobsen BW, Lund B, Lind M (2008) Isolated repair of the medial patellofemoral ligament in primary dislocation of the patella: a prospective randomized study. Arthroscopy 24(8):881–887

    Article  PubMed  Google Scholar 

  12. Conchie H, Clark D, Metcalfe A, Eldridge J, Whitehouse M (2016) Adolescent knee pain and patellar dislocations are associated with patellofemoral osteoarthritis in adulthood: a case control study. Knee 23(4):708–711

    Article  PubMed  Google Scholar 

  13. Dejour H, Walch G, Nove-Josserand L, Guier C (1994) Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc 2(1):19–26

    Article  CAS  PubMed  Google Scholar 

  14. Diederichs G, Issever AS, Scheffler S (2010) MR imaging of patellar instability: injury patterns and assessment of risk factors. Radiographics 30(4):961–981

    Article  PubMed  Google Scholar 

  15. Dietrich TJ, Fucentese SF, Pfirrmann CWA (2016) Imaging of individual anatomical risk factors for patellar instability. Semin Musculoskelet Radiol 20(1):65–73

    Article  PubMed  Google Scholar 

  16. Elias DA, White LM, Fithian DC (2002) Acute lateral patellar dislocation at MR imaging: injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella. Radiology 225(3):736–743

    Article  PubMed  Google Scholar 

  17. Felus J, Kowalczyk B (2012) Age-related differences in medial patellofemoral ligament injury patterns in traumatic patellar dislocation: case series of 50 surgically treated children and adolescents. Am J Sports Med 40(10):2357–2364

    Article  PubMed  Google Scholar 

  18. 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(5):1114–1121

    Article  PubMed  Google Scholar 

  19. Fox AJS, Wanivenhaus F, Rodeo SA (2012) The basic science of the patella: structure, composition, and function. J Knee Surg 25(2):127–141

    Article  PubMed  Google Scholar 

  20. Guerrero P, Li X, Patel K, Brown M, Busconi B (2009) Medial patellofemoral ligament injury patterns and associated pathology in lateral patella dislocation: an MRI study. Sports Med Arthrosc Rehabil Ther Technol 1(1):17

    PubMed  PubMed Central  Google Scholar 

  21. Kaleka CC, Aihara LJ, Rodrigues A, de Medeiros SF, de Oliveira VM, de Paula Leite Cury R (2017) Cadaveric study of the secondary medial patellar restraints: patellotibial and patellomeniscal ligaments. Knee Surg Sports Traumatol Arthrosc 25(1):144–151

    Article  PubMed  Google Scholar 

  22. Kang HJ, Wang F, Chen BC, Zhang YZ, Ma L (2013) Non-surgical treatment for acute patellar dislocation with special emphasis on the MPFL injury patterns. Knee Surg Sports Traumatol Arthrosc 21(2):325–331

    Article  PubMed  Google Scholar 

  23. Kepler CK, Bogner EA, Hammoud S, Malcolmson G, Potter HG, Green DW (2011) Zone of injury of the medial patellofemoral ligament after acute patellar dislocation in children and adolescents. Am J Sports Med 39(7):1444–1449

    Article  PubMed  Google Scholar 

  24. Koh JL, Stewart C (2014) Patellar instability. Clin Sports Med 33(3):461–476

    Article  PubMed  Google Scholar 

  25. Mundy A, Ravindra A, Yang J, Adler BH, Klingele KE (2016) Standardization of patellofemoral morphology in the pediatric knee. Pediatr Radiol 46(2):255–262

    Article  PubMed  Google Scholar 

  26. Panagiotopoulos E, Strzelczyk P, Herrmann M, Scuderi G (2006) Cadaveric study on static medial patellar stabilizers: the dynamizing role of the vastus medialis obliquus on medial patellofemoral ligament. Knee Surg Sports Traumatol Arthrosc 14(1):7–12

    Article  PubMed  Google Scholar 

  27. Petri M, von Falck C, Broese M, Liodakis E, Balcarek P, Niemeyer P, Hofmeister M, Krettek C, Voigt C, Haasper C, Zeichen J, Frosch KH, Lill H, Jagodzinski M (2013) Influence of rupture patterns of the medial patellofemoral ligament (MPFL) on the outcome after operative treatment of traumatic patellar dislocation. Knee Surg Sports Traumatol Arthrosc 21(3):683–689

    Article  CAS  PubMed  Google Scholar 

  28. Pfirrmann CW, Zanetti M, Romero J, Hodler J (2000) Femoral trochlear dysplasia: MR findings. Radiology 216(3):858–864

    Article  CAS  PubMed  Google Scholar 

  29. Putney SA, Smith CS, Neal KM (2012) The location of medial patellofemoral ligament injury in adolescents and children. J Pediatr Orthop 32(3):241–244

    Article  PubMed  Google Scholar 

  30. Quinlan JF, Farrelly C, Kelly G, Eustace S (2010) Co-existent medial collateral ligament injury seen following transient patellar dislocation: observations at magnetic resonance imaging. Br J Sports Med 44(6):411–414

    Article  CAS  PubMed  Google Scholar 

  31. Saggin PRF, Saggin JI, Dejour D (2012) Imaging in patellofemoral instability: an abnormality-based approach. Sports Med Arthrosc 20(3):145–151

    Article  PubMed  Google Scholar 

  32. Seeley M, Bowman KF, Walsh C, Sabb BJ, Vanderhave KL (2012) Magnetic resonance imaging of acute patellar dislocation in children: Patterns of injury and risk factors for recurrence. J Pediatr Orthop 32(2):145–155

    Article  PubMed  Google Scholar 

  33. Siebold R, Karidakis G, Fernandez F (2014) Clinical outcome after medial patellofemoral ligament reconstruction and autologous chondrocyte implantation following recurrent patella dislocation. Knee Surg Sports Traumatol Arthrosc 22(10):2477–2483

    Article  PubMed  Google Scholar 

  34. Sillanpaa PJ, Maenpaa HM (2012) First-time patellar dislocation: surgery or conservative treatment? Sports Med Arthrosc 20(3):128–135

    Article  PubMed  Google Scholar 

  35. Sillanpaa PJ, Peltola E, Mattila VM, Kiuru M, Visuri T, Pihlajamaki H (2009) Femoral avulsion of the medial patellofemoral ligament after primary traumatic patellar dislocation predicts subsequent instability in men: a mean 7-year nonoperative follow-up study. Am J Sports Med 37(8):1513–1521

    Article  PubMed  Google Scholar 

  36. Sillanpaa PJ, Salonen E, Pihlajamaki H, Maenpaa HM (2014) Medial patellofemoral ligament avulsion injury at the patella: classification and clinical outcome. Knee Surg Sports Traumatol Arthrosc 22(10):2414–2418

    Article  PubMed  Google Scholar 

  37. Stanitski CL, Paletta GA Jr (1998) Articular cartilage injury with acute patellar dislocation in adolescents. Arthroscopic and radiographic correlation. Am J Sports Med 26(1):52–55

    Article  CAS  PubMed  Google Scholar 

  38. Thawait SK, Soldatos T, Thawait GK, Cosgarea AJ, Carrino JA, Chhabra A (2012) High resolution magnetic resonance imaging of the patellar retinaculum: normal anatomy, common injury patterns, and pathologies. Skeletal Radiol 41(2):137–148

    Article  PubMed  Google Scholar 

  39. Tsai C-H, Hsu C-J, Hung C-H, Hsu H-C (2012) Primary traumatic patellar dislocation. J Orthop Surg Res 7:21

    Article  PubMed  PubMed Central  Google Scholar 

  40. Weber-Spickschen TS, Spang J, Kohn L, Imhoff AB, Schottle PB (2011) The relationship between trochlear dysplasia and medial patellofemoral ligament rupture location after patellar dislocation: an MRI evaluation. Knee 18(3):185–188

    Article  CAS  PubMed  Google Scholar 

  41. Zaidi A, Babyn P, Astori I, White L, Doria A, Cole W (2006) MRI of traumatic patellar dislocation in children. Pediatr Radiol 36(11):1163–1170

    Article  PubMed  Google Scholar 

  42. Zhang G-y, Zheng L, Feng Y, Shi H, Liu W, Ji B-j, Sun B-s, Ding H-y (2015) Injury patterns of medial patellofemoral ligament and correlation analysis with articular cartilage lesions of the lateral femoral condyle after acute lateral patellar dislocation in adults: an MRI evaluation. Injury 46(12):2413–2421

    Article  PubMed  Google Scholar 

  43. Zhang G-Y, Zheng L, Shi H, Ji B-J, Feng Y, Ding H-Y (2017) Injury patterns of medial patellofemoral ligament after acute lateral patellar dislocation in children: correlation analysis with anatomical variants and articular cartilage lesion of the patella. Eur Radiol 27(3):1322–1330

    Article  PubMed  Google Scholar 

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Authors and Affiliations

  1. Department of Orthopaedic Surgery, University of Minnesota, 2450 Riverside Avenue South Suite R200, Minneapolis, MN, 55454, USA

    Marc A. Tompkins, Julie Agel & Elizabeth A. Arendt

  2. TRIA Orthopaedic Center, 8100 Northland Drive, Bloomington, MN, 55431, USA

    Marc A. Tompkins & Elizabeth A. Arendt

  3. Center for Diagnostic Imaging, 5775 Wayzata Boulevard, Suite 190, St. Louis Park, MN, 55416, USA

    Sara R. Rohr

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  1. Marc A. Tompkins
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Correspondence to Elizabeth A. Arendt.

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There was no funding for this study.

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Institutional Review Board (IRB) approval was obtained from the IRB (study number 1005E82296) prior to initiation of this study.

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Informed consent was not obtained for this study. This research involved the study of existing data.

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Tompkins, M.A., Rohr, S.R., Agel, J. et al. Anatomic patellar instability risk factors in primary lateral patellar dislocations do not predict injury patterns: an MRI-based study. Knee Surg Sports Traumatol Arthrosc 26, 677–684 (2018). https://doi.org/10.1007/s00167-017-4464-3

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