Acute Patellar Dislocation (First-Time Dislocator)

  • Jacqueline Munch BradyEmail author


Patellar dislocation most commonly occurs in the adolescent female population. Trochlear dysplasia is the most predictive risk factor for recurrence after first-time dislocation. Other factors include patellar height, young age and/or open physes, patella alta, high TT-TG distance, rotational malalignment, and patient factors such as ligamentous laxity and jumping/landing mechanics. The medial patellofemoral ligament complex is injured in the vast majority of patients after patellar instability, and chondral/osteochondral injuries are also common. The standard of care for first-time dislocators has historically been non-operative, unless a loose osteochondral body is discovered on imaging. The recent literature has identified young patients with trochlear dysplasia as a high-risk group for recurrence, however, prompting increased attention to treatment options. MPFL repair is thought to be acceptable only when the injury to the ligament is discrete, and controversy exists regarding its efficacy. MPFL reconstruction has become the standard of care intervention for first-time dislocations when surgery is indicated.


Patellofemoral Instability Knee 


  1. 1.
    Lewallen LW, McIntosh AL, Dahm DL. Predictors of recurrent instability after acute patellofemoral dislocation in pediatric and adolescent patients. Am J Sports Med. 2013;41(3):575–81. Scholar
  2. 2.
    Fithian DC, Paxton EW, Stone ML, et al. Epidemiology and natural history of acute patellar dislocation. Am J Sport Med. 2004;32:1114–21.CrossRefGoogle Scholar
  3. 3.
    Atkin DM, Fithian DC, Marangi KS, Stone ML, Dobson BE, Mendelsohn C. Characteristics of patients with primary acute lateral patellar dislocation and their recovery within the first 6 months of injury. Am J Sports Med. 2000;28(4):472–9. Scholar
  4. 4.
    Elias DA, White LM. Acute lateral patellar dislocation at MR imaging: injury patterns of medial patellar soft-tissue restraints and osteochondral injuries of the inferomedial patella. Radiology. 2002;225(3):736–43.CrossRefGoogle Scholar
  5. 5.
    Lewallen L, Mcintosh A, Dahm D. First-time patellofemoral dislocation: risk factors for recurrent instability. J Knee Surg. 2015;28(4):303–9. Scholar
  6. 6.
    Nomura E, Inoue M. Second-look arthroscopy of cartilage changes of the patellofemoral joint, especially the patella, following acute and recurrent patellar dislocation. Osteoarthr Cartil. 2005;13(11):1029–36. Scholar
  7. 7.
    Askenberger M, Janarv P-M, Finnbogason T, Arendt EA. Morphology and anatomic patellar instability risk factors in first-time traumatic lateral patellar dislocations: a prospective magnetic resonance imaging study in skeletally immature children. Am J Sports Med. 2016;45:50–8. Scholar
  8. 8.
    Li W, Wang Q, Wang F, Zhang Y, Ma L, Dong J. Femoral trochlear dysplasia after patellar dislocation in rabbits. Knee. 2013;20(6):485–9. Scholar
  9. 9.
    Desio SM, Burks RT, Bachus KN. Soft tissue restraints to lateral patellar translation in the human knee. Am J Sport Med. 1998;26(1):59–65.CrossRefGoogle Scholar
  10. 10.
    Arendt EA. MPFL reconstruction for PF instability: the soft (tissue) approach. Orthop Traumatol Surg Res. 2009;95(8):97–100.CrossRefGoogle Scholar
  11. 11.
    Amis AA, Firer P, Mountney J, Senavongse W, Thomas NP. Anatomy and biomechanics of the medial patellofemoral ligament. Knee. 2003;10:215–20. Scholar
  12. 12.
    Cattalini M, Khubchandani R, Cimas R. When flexibility is not necessarily a virtue: a review of hypermobility syndromes and chronic or recurrent musculoskeletal pain in children. Pediatr Rheumatol Online J. 2015;13(1):40.CrossRefGoogle Scholar
  13. 13.
    Mitchell J, Magnussen RA, Collins CL, et al. Epidemiology of overuse injuries among high school athletes in the United States. Am J Sports Med. 2015;43(7):1676–82. Scholar
  14. 14.
    Rood A, Boons H, Ploegmakers J, van der Stappen W, Koeter S. Tape versus cast for non-operative treatment of primary patellar dislocation: a randomized controlled trial. Arch Orthop Trauma Surg. 2012;132(8):1199–203.CrossRefGoogle Scholar
  15. 15.
    Liu JN, Steinhaus ME, Kalbian IL, Post WR, Green DW, Strickland SM, Shubin Stein BE. Patellar instability management: a survey of the International Patellofemoral Study Group. Am J Sports Med. 2018;46(13):3299–306. Epub 2017 Oct 6.CrossRefGoogle Scholar
  16. 16.
    Kepler CK, Bogner EA, Hammoud S, Malcolmson G, Potter HG, Green DW. Zone of injury of the medial patellofemoral ligament after acute patellar dislocation in children and adolescents. Am J Sports Med. 2011;39(7):1444–9. Scholar
  17. 17.
    Askenberger M, Arendt EA, Ekstro MW, Voss U, Finnbogason T, Janarv P-M. Medial patellofemoral ligament injuries in children with first-time lateral patellar dislocations: a magnetic resonance imaging and arthroscopic study. Am J Sports Med. 2016;44(1):152–8. Scholar
  18. 18.
    Camanho GL, Viegas ADC, Bitar AC, Demange MK, Hernandez AJ. Conservative versus surgical treatment for repair of the medial patellofemoral ligament in acute dislocations of the Patella. Arthroscopy. 2009;25(6):620–5. Scholar
  19. 19.
    Christiansen SE, Jakobsen BW, Lund B, Lind M. Isolated repair of the medial patellofemoral ligament in primary dislocation of the Patella: a prospective randomized study. Arthroscopy. 2008;24(8):881–7. Scholar
  20. 20.
    Palmu S, Kallio PE, Donell ST, et al. Treatment with and without initial stabilizing surgery for primary traumatic patellar dislocation. A prospective randomized study. J Bone Joint Surg Am. 2008;24(12):620–5. Scholar
  21. 21.
    Arendt EA, Moeller A, Agel J. Clinical outcomes of medial patellofemoral ligament repair in recurrent (chronic) lateral patella dislocations. Knee Surg Sports Tramatol Arthrosc. 2011;19:1909–14.CrossRefGoogle Scholar

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Department of Orthopaedics and RehabilitationOregon Health and Science UniversityPortlandUSA

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