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Patellar Injury and Dislocation Follow-up

  • Author: Gerard A Malanga, MD; Chief Editor: Craig C Young, MD  more...
Updated: Sep 11, 2014

Return to Play

Patients with patellar injury and dislocation may return to play after (1) all symptoms and episodes or exacerbations have resolved and (2) full ROM and preinjury strength have been achieved in the affected limb. The timeline for return to play varies from patient to patient. In a 2000 study, Atkin et al found that at 6 months, 58% of their study population still reported deficits in function.[54]

Some variability exists in the time required to return to play, and it depends on multiple factors, including the underlying anatomy and physiology, whether conservative or surgical treatment was used, and the type of surgical treatment performed. In a review article in 2003, Hinton et al suggested that following surgical correction of a patellar injury or dislocation, return to sports can be anticipated to occur 4-6 months after the procedure.[55]



To prevent patellofemoral knee problems, patients must not exceed the optimal patellofemoral joint-loading capacities. In addition, enhancing quadriceps strength prevents most symptoms and pathologies. Athletes involved in soccer and weight lifting should be especially careful. Studies on prophylactic bracing for patellofemoral dysfunction have thus far been inconclusive. The variability in results from bracing is likely due to the different subtleties of patellofemoral biomechanics in each individual. Each brace fits and affects different muscle groups to different degrees in different individuals.



The prognosis for patellofemoral dysfunction and dislocation has been studied and reports of outcomes vary. Overall, conservative treatment for acute patellar dislocations yields a 30-50% chance of continuing to have long-term symptoms of instability or pain.

  • Cash et al reported on a 30-year noninvasive rehabilitation treatment course for patients with and without congenital anomalies of the extensor mechanism who had an acute patellar dislocation.[56] Of the 54 patients with congenital anomalies, 28 (52%) reported good or excellent results. Of the 20 patients without congential anomalies, 15 (75%) reported good or excellent results.[56]
  • Buchner et al evaluated a total of 126 patients who had a primary traumatic patella dislocation and were treated either conservatively, with arthroscopic exploration, or with immediate surgical repair of the parapatellar ligaments.[33] After a mean follow-up of 8.1 years, the study reported long-term functional results as excellent or good in 85% of patients. However, the investigators also noted a recurrence rate of 26% in the total study population.[33]
  • Atkin et al investigated 74 young athletes who received standardized rehabilitation after acute patellar dislocation during sporting events.[54] After full passive ROM and quadriceps strength were at least 80% compared with the uninvolved knee, these patients returned to sports activity. Up to 6 months after the initial insult, participation in strenuous activity, especially kneeling and squatting, was significantly reduced. At 6 months, 58% continued to note a reduced ability to fully participate.[54]


See Prevention.

Contributor Information and Disclosures

Gerard A Malanga, MD Founder and Partner, New Jersey Sports Medicine, LLC and New Jersey Regenerative Institute; Director of Research, Atlantic Health; Clinical Professor, Department of Physical Medicine and Rehabilitation, University of Medicine and Dentistry of New Jersey-New Jersey Medical School; Fellow, American College of Sports Medicine

Gerard A Malanga, MD is a member of the following medical societies: Alpha Omega Alpha, American Institute of Ultrasound in Medicine, North American Spine Society, International Spine Intervention Society, American Academy of Physical Medicine and Rehabilitation, American College of Sports Medicine

Disclosure: Received honoraria from Cephalon for speaking and teaching; Received honoraria from Endo for speaking and teaching; Received honoraria from Genzyme for speaking and teaching; Received honoraria from Prostakan for speaking and teaching; Received consulting fee from Pfizer for speaking and teaching.


Wah Sang Lee, DO, MS Staff Physician, Department of Physical Medicine and Rehabilitation, New Jersey Medical School/Kessler Institute of Rehabilitation

Wah Sang Lee, DO, MS is a member of the following medical societies: American Osteopathic Association

Disclosure: Nothing to disclose.

Thomas Agesen, MD Assistant Clinical Professor, Department of Physical Medicine and Rehabilitation, University of Medicine and Dentistry of New Jersey, New Jersey Medical School; Consulting Staff, Mountainside Hospital, Summit Overlook Hospital

Thomas Agesen, MD is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American College of Sports Medicine, Physiatric Association of Spine, Sports and Occupational Rehabilitation

Disclosure: Nothing to disclose.

Brian F White, DO Attending Physiatrist, Department of Surgery, Division of Interventional Pain, Bassett Healthcare, Cooperstown, NY

Brian F White, DO is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Osteopathic Association, North American Spine Society, American Society of Interventional Pain Physicians, International Spine Intervention Society

Disclosure: Nothing to disclose.

Daniel Tsukanov, DO Sports Medicine Fellow, Department of Physical Medicine and Rehabilitation, Montefiore Medical Center

Daniel Tsukanov, DO is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American College of Sports Medicine, American Osteopathic Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Russell D White, MD Clinical Professor of Medicine, Clinical Professor of Orthopedic Surgery, Department of Community and Family Medicine, University of Missouri-Kansas City School of Medicine, Truman Medical Center-Lakewood

Russell D White, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Family Physicians, American Association of Clinical Endocrinologists, American College of Sports Medicine, American Diabetes Association, American Medical Society for Sports Medicine

Disclosure: Nothing to disclose.

Chief Editor

Craig C Young, MD Professor, Departments of Orthopedic Surgery and Community and Family Medicine, Medical Director of Sports Medicine, Medical College of Wisconsin

Craig C Young, MD is a member of the following medical societies: American Academy of Family Physicians, American College of Sports Medicine, American Medical Society for Sports Medicine, Phi Beta Kappa

Disclosure: Nothing to disclose.

Additional Contributors

Andrew L Sherman, MD, MS Associate Professor of Clinical Rehabilitation Medicine, Vice Chairman, Chief of Spine and Musculoskeletal Services, Program Director, SCI Fellowship and PMR Residency Programs, Department of Rehabilitation Medicine, University of Miami, Leonard A Miller School of Medicine

Andrew L Sherman, MD, MS is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine, American Medical Association, Association of Academic Physiatrists

Disclosure: Nothing to disclose.

  1. Raty HP, Kujala UM, Videman T, et al. Lifetime musculoskeletal symptoms and injuries among former elite male athletes. Int J Sports Med. 1997 Nov. 18(8):625-32. [Medline].

  2. Thijs Y, De Clercq D, Roosen P, Witvrouw E. Gait-related intrinsic risk factors for patellofemoral pain in novice recreational runners. Br J Sports Med. 2008 Jun. 42(6):466-71. [Medline].

  3. Hahn T, Foldspang A. Prevalent knee pain and sport. Scand J Soc Med. 1998 Mar. 26(1):44-52. [Medline].

  4. Aoyagi K, Ross PD, et al. Prevalence of joint pain is higher among women in rural Japan than urban Japanese-American women in Hawaii. Ann Rheum Dis. 1999 May. 58(5):315-9. [Medline]. [Full Text].

  5. Zhang Y, Xu L, Nevitt MC, et al. Comparison of the prevalence of knee osteoarthritis between the elderly Chinese population in Beijing and whites in the United States: The Beijing Osteoarthritis Study. Arthritis Rheum. 2001 Sep. 44(9):2065-71. [Medline]. [Full Text].

  6. Nietosvaara Y, Aalto K, Kallio PE. Acute patellar dislocation in children: incidence and associated osteochondral fractures. J Pediatr Orthop. 1994 Jul-Aug. 14(4):513-5. [Medline].

  7. Andrikoula S, Tokis A, Vasiliadis HS, Georgoulis A. The extensor mechanism of the knee joint: an anatomical study. Knee Surg Sports Traumatol Arthrosc. 2006 Mar. 14(3):214-20. [Medline].

  8. 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 Jul. 39(7):1444-9. [Medline].

  9. Escala JS, Mellado JM, Olona M, et al. Objective patellar instability: MR-based quantitative assessment of potentially associated anatomical features. Knee Surg Sports Traumatol Arthrosc. 2006 Mar. 14(3):264-72. [Medline].

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

  11. Post WR, Teitge R, Amis A. Patellofemoral malalignment: looking beyond the viewbox. Clin Sports Med. 2002 Jul. 21(3):521-46, x. [Medline].

  12. Bongers EM, van Kampen A, van Bokhoven H, Knoers NV. Human syndromes with congenital patellar anomalies and the underlying gene defects. Clin Genet. 2005 Oct. 68(4):302-19. [Medline].

  13. Amin S, Goggins J, Niu J, et al. Occupation-related squatting, kneeling, and heavy lifting and the knee joint: a magnetic resonance imaging-based study in men. J Rheumatol. 2008 Aug. 35(8):1645-9. [Medline].

  14. Grelsamer RP, Dubey A, Weinstein CH. Men and women have similar Q angles: a clinical and trigonometric evaluation. J Bone Joint Surg Br. 2005 Nov. 87(11):1498-501. [Medline].

  15. Verma A, Su A, Golin AM, O'Marrah B, Amorosa JK. A screening method for knee trauma. Acad Radiol. 2001 May. 8(5):392-7. [Medline].

  16. Stanciu C, Labelle HB, Morin B, Fassier F, Marton D. The value of computed tomography for the diagnosis of recurrent patellar subluxation in adolescents. Can J Surg. 1994 Aug. 37(4):319-23. [Medline].

  17. Shea KP, Fulkerson JP. Preoperative computed tomography scanning and arthroscopy in predicting outcome after lateral retinacular release. Arthroscopy. 1992. 8(3):327-34. [Medline].

  18. McNally EG, Ostlere SJ, Pal C, et al. Assessment of patellar maltracking using combined static and dynamic MRI. Eur Radiol. 2000. 10(7):1051-5. [Medline].

  19. Guerrero P, Li X, Patel K, Brown M, Busconi B. Medial patellofemoral ligament injury patterns and associated pathology in lateral patella dislocation: an MRI study. Sports Med Arthrosc Rehabil Ther Technol. 2009 Jul 30. 1(1):17. [Medline]. [Full Text].

  20. Brossmann J, Muhle C, Büll CC, et al. Evaluation of patellar tracking in patients with suspected patellar malalignment: cine MR imaging vs arthroscopy. AJR Am J Roentgenol. 1994 Feb. 162(2):361-7. [Medline]. [Full Text].

  21. Watanabe A, Obata T, Ikehira H, et al. Degeneration of patellar cartilage in patients with recurrent patellar dislocation following conservative treatment: evaluation with delayed gadolinium-enhanced magnetic resonance imaging of cartilage. Osteoarthritis Cartilage. 2009 Dec. 17(12):1546-53. [Medline].

  22. Felus J, Kowalczyk B, Lejman T. Sonographic evaluation of the injuries after traumatic patellar dislocation in adolescents. J Pediatr Orthop. 2008 Jun. 28(4):397-402. [Medline].

  23. Maenpaa H, Lehto MU. Patellar dislocation. The long-term results of nonoperative management in 100 patients. Am J Sports Med. 1997 Mar-Apr. 25(2):213-7. [Medline].

  24. Colvin AC, West RV. Patellar instability. J Bone Joint Surg Am. 2008 Dec. 90(12):2751-62. [Medline].

  25. Neptune RR, Wright IC, van den Bogert AJ. The influence of orthotic devices and vastus medialis strength and timing on patellofemoral loads during running. Clin Biomech (Bristol, Avon). 2000 Oct. 15(8):611-8. [Medline].

  26. Shellock FG, Mink JH, Deutsch AL, Molnar T. Effect of a newly designed patellar realignment brace on patellofemoral relationships. Med Sci Sports Exerc. 1995 Apr. 27(4):469-72. [Medline].

  27. Gilleard W, McConnell J, Parsons D. The effect of patellar taping on the onset of vastus medialis obliquus and vastus lateralis muscle activity in persons with patellofemoral pain. Phys Ther. 1998 Jan. 78(1):25-32. [Medline]. [Full Text].

  28. Arendse RE, Noakes TD, Azevedo LB, Romanov N, Schwellnus MP, Fletcher G. Reduced eccentric loading of the knee with the pose running method. Med Sci Sports Exerc. 2004 Feb. 36(2):272-7. [Medline].

  29. Bonacci J, Vicenzino B, Spratford W, Collins P. Take your shoes off to reduce patellofemoral joint stress during running. Br J Sports Med. 2014 Mar. 48(6):425-8. [Medline].

  30. Tam N, Astephen Wilson JL, Noakes TD, Tucker R. Barefoot running: an evaluation of current hypothesis, future research and clinical applications. Br J Sports Med. 2014 Mar. 48(5):349-55. [Medline].

  31. Mohr KJ, Kvitne RS, Pink MM, Fideler B, Perry J. Electromyography of the quadriceps in patellofemoral pain with patellar subluxation. Clin Orthop Relat Res. 2003 Oct. 415:261-71. [Medline].

  32. Earl JE, Schmitz RJ, Arnold BL. Activation of the VMO and VL during dynamic mini-squat exercises with and without isometric hip adduction. J Electromyogr Kinesiol. 2001 Dec. 11(6):381-6. [Medline].

  33. Buchner M, Baudendistel B, Sabo D, Schmitt H. Acute traumatic primary patellar dislocation: long-term results comparing conservative and surgical treatment. Clin J Sport Med. 2005 Mar. 15(2):62-6. [Medline].

  34. Camanho GL, Viegas Ade C, 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 Jun. 25(6):620-5. [Medline].

  35. Cootjans K, Dujardin J, Vandenneucker H, Bellemans J. A surgical algorithm for the treatment of recurrent patellar dislocation. Results at 5 year follow-up. Acta Orthop Belg. 2013 Jun. 79(3):318-25. [Medline].

  36. Arendt EA, Fithian DC, Cohen E. Current concepts of lateral patella dislocation. Clin Sports Med. 2002 Jul. 21(3):499-519. [Medline].

  37. Sillanpaa P, Mattila VM, Visuri T, Maenpaa H, Pihlajamaki H. Ligament reconstruction versus distal realignment for patellar dislocation. Clin Orthop Relat Res. 2008 Jun. 466(6):1475-84. [Medline]. [Full Text].

  38. Panagopoulos A, van Niekerk L, Triantafillopoulos IK. MPFL reconstruction for recurrent patella dislocation: a new surgical technique and review of the literature. Int J Sports Med. 2008 May. 29(5):359-65. [Medline].

  39. Zhao J, Huangfu X, He Y. The role of medial retinaculum plication versus medial patellofemoral ligament reconstruction in combined procedures for recurrent patellar instability in adults. Am J Sports Med. 2012 Jun. 40(6):1355-64. [Medline].

  40. Xie G, Zhao J, Huangfu X, He Y. Medial patellofemoral ligament reconstruction using semitendinosus tendons: polyester suture augmentation versus nonaugmentation. Am J Sports Med. 2012 Jun. 40(6):1365-74. [Medline].

  41. Krause F, Kolling C, Brantschen R, Sieber HP. [Medium-term results after m. vastus medialis obliquus-plasty for lateral patellar dislocation] [German]. Orthopade. 2006 Jan. 35(1):94-101. [Medline].

  42. Zhao J, Huangfu X, He Y, Liu W. Recurrent patellar dislocation in adolescents: medial retinaculum plication versus vastus medialis plasty. Am J Sports Med. 2012 Jan. 40(1):123-32. [Medline].

  43. Ma LF, Wang F, Chen BC, Wang CH, Zhou JW, Wang HY. Medial retinaculum plasty versus medial patellofemoral ligament reconstruction for recurrent patellar instability in adults: a randomized controlled trial. Arthroscopy. 2013 May. 29(5):891-7. [Medline].

  44. Christoforakis J, Bull AM, Strachan RK, et al. Effects of lateral retinacular release on the lateral stability of the patella. Knee Surg Sports Traumatol Arthrosc. 2006 Mar. 14(3):273-7. [Medline].

  45. Haspl M, Cicak N, Klobucar H, Pecina M. Fully arthroscopic stabilization of the patella. Arthroscopy. 2002 Jan. 18(1):E2. [Medline].

  46. Nam EK, Karzel RP. Mini-open medial reefing and arthroscopic lateral release for the treatment of recurrent patellar dislocation: a medium-term follow-up. Am J Sports Med. 2005 Feb. 33(2):220-30. [Medline].

  47. Maenpää H, Lehto MU. Surgery in acute patellar dislocation--evaluation of the effect of injury mechanism and family occurrence on the outcome of treatment. Br J Sports Med. 1995 Dec. 29(4):239-41. [Medline]. [Full Text].

  48. Cossey AJ, Paterson R. A new technique for reconstructing the medial patellofemoral ligament. Knee. 2005 Apr. 12(2):93-8. [Medline].

  49. Mikashima Y, Kimura M, Kobayashi Y, Asagumo H, Tomatsu T. Medial patellofemoral ligament reconstruction for recurrent patellar instability. Acta Orthop Belg. 2004 Dec. 70(6):545-50. [Medline].

  50. Nelitz M, Dreyhaupt J, Lippacher S. Combined trochleoplasty and medial patellofemoral ligament reconstruction for recurrent patellar dislocations in severe trochlear dysplasia: a minimum 2-year follow-up study. Am J Sports Med. 2013 May. 41(5):1005-12. [Medline].

  51. Ntagiopoulos PG, Byn P, Dejour D. Midterm results of comprehensive surgical reconstruction including sulcus-deepening trochleoplasty in recurrent patellar dislocations with high-grade trochlear dysplasia. Am J Sports Med. 2013 May. 41(5):998-1004. [Medline].

  52. Wu LS. Evaluation and manipulative therapy of patellar malalignment: a clinical review and preliminary report. J Manipulative Physiol Ther. 1991 Sep. 14(7):428-35. [Medline].

  53. Brosseau L, Casimiro L, Robinson V, et al. Therapeutic ultrasound for treating patellofemoral pain syndrome. Cochrane Database Syst Rev. 2001. CD003375. [Medline]. [Full Text].

  54. Atkin DM, Fithian DC, Marangi KS, et al. Characteristics of patients with primary acute lateral patellar dislocation and their recovery within the first 6 months of injury. Am J Sports Med. 2000 Jul-Aug. 28(4):472-9. [Medline].

  55. Hinton RY, Sharma KM. Acute and recurrent patellar instability in the young athlete. Orthop Clin North Am. 2003 Jul. 34(3):385-96. [Medline].

  56. Cash JD, Hughston JC. Treatment of acute patellar dislocation. Am J Sports Med. 1988 May-Jun. 16(3):244-9. [Medline].

  57. Altman AR, Davis IS. Barefoot running: biomechanics and implications for running injuries. Curr Sports Med Rep. 2012 Sep-Oct. 11(5):244-50. [Medline].

  58. Andrish J. The management of recurrent patellar dislocation. Orthop Clin North Am. 2008 Jul. 39(3):313-27, vi. [Medline].

  59. Beaconsfield T, Pintore E, Maffulli N, Petri GJ. Radiological measurements in patellofemoral disorders. A review. Clin Orthop Relat Res. 1994 Nov. 308:18-28. [Medline].

  60. Beasley LS, Vidal AF. Traumatic patellar dislocation in children and adolescents: treatment update and literature review. Curr Opin Pediatr. 2004 Feb. 16(1):29-36. [Medline].

  61. BenGal S, Lowe J, Mann G, Finsterbush A, Matan Y. The role of the knee brace in the prevention of anterior knee pain syndrome. Am J Sports Med. 1997 Jan-Feb. 25(1):118-22. [Medline].

  62. Bensahel H, Souchet P, Pennecot GF, Mazda K. The unstable patella in children. J Pediatr Orthop B. 2000 Oct. 9(4):265-70. [Medline].

  63. Boden BP, Pearsall AW, Garrett WE Jr, Feagin JA Jr. Patellofemoral Instability: Evaluation and Management. J Am Acad Orthop Surg. 1997 Jan. 5(1):47-57. [Medline].

  64. Brody LT, Thein JM. Nonoperative treatment for patellofemoral pain. J Orthop Sports Phys Ther. 1998 Nov. 28(5):336-44. [Medline].

  65. Bui KL, Ilaslan H, Parker RD, Sundaram M. Knee dislocations: a magnetic resonance imaging study correlated with clinical and operative findings. Skeletal Radiol. 2008 Jul. 37(7):653-61. [Medline].

  66. Burgess KE, Pearson SJ, Onambele GL. Patellar tendon properties with fluctuating menstrual cycle hormones. J Strength Cond Res. 2009 Nov 13. epub ahead of print. [Medline].

  67. Chapman MW, ed. Chapman's Orthopaedic Surgery. 3rd ed. Baltimore, Md: Lippincott Williams & Wilkins; 1993. Vol 2:

  68. 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 Aug. 24(8):881-7. [Medline].

  69. Connolly JF. Fractures and Dislocations: Closed Management. Philadelphia, Pa: WB Saunders Co; 1995.

  70. Csintalan RP, Latt LD, Fornalski S, Raiszadeh K, Inacio MC, Fithian DC. Medial patellofemoral ligament (MPFL) reconstruction for the treatment of patellofemoral instability. J Knee Surg. 2014 Apr. 27(2):139-46. [Medline].

  71. Eckstein F, Adam C, Sittek H, et al. Non-invasive determination of cartilage thickness throughout joint surfaces using magnetic resonance imaging. J Biomech. 1997 Mar. 30(3):285-9. [Medline].

  72. Eckstein F, Schnier M, Haubner M, et al. Accuracy of cartilage volume and thickness measurements with magnetic resonance imaging. Clin Orthop Relat Res. 1998 Jul. 352:137-48. [Medline].

  73. Elias DA, White LM. Imaging of patellofemoral disorders. Clin Radiol. 2004 Jul. 59(7):543-57. [Medline].

  74. Fithian DC, Paxton EW, Cohen AB. Indications in the treatment of patellar instability. J Knee Surg. 2004 Jan. 17(1):47-56. [Medline].

  75. Fulkerson JP. Alternatives to patellofemoral arthroplasty. Clin Orthop Relat Res. 2005 Jul. 436:76-80. [Medline].

  76. Gagliardi JA, Chung EM, Chandnani VP, et al. Detection and staging of chondromalacia patellae: relative efficacies of conventional MR imaging, MR arthrography, and CT arthrography. AJR Am J Roentgenol. 1994 Sep. 163(3):629-36. [Medline]. [Full Text].

  77. Grelsamer RP, Klein JR. The biomechanics of the patellofemoral joint. J Orthop Sports Phys Ther. 1998 Nov. 28(5):286-98. [Medline].

  78. Grood ES, Suntay WJ, Noyes FR, Butler DL. Biomechanics of the knee-extension exercise. Effect of cutting the anterior cruciate ligament. J Bone Joint Surg Am. 1984 Jun. 66(5):725-34. [Medline].

  79. Handelberg F, Shahabpour M, Casteleyn PP. Chondral lesions of the patella evaluated with computed tomography, magnetic resonance imaging, and arthroscopy. Arthroscopy. 1990. 6(1):24-9. [Medline].

  80. Handelberg F, Shahabpour M, Van Betten F, et al. CT arthrography and MRI of the patella. Acta Orthop Belg. 1989. 55(3):331-8. [Medline].

  81. Hawkins RJ, Bell RH, Anisette G. Acute patellar dislocations. The natural history. Am J Sports Med. 1986 Mar-Apr. 14(2):117-20. [Medline].

  82. Holmes SW Jr, Clancy WG Jr. Clinical classification of patellofemoral pain and dysfunction. J Orthop Sports Phys Ther. 1998 Nov. 28(5):299-306. [Medline].

  83. Ireland ML, Chang JL. Acute fracture bipartite patella: case report and literature review. Med Sci Sports Exerc. 1995 Mar. 27(3):299-302. [Medline].

  84. Kapur S, Wissman RD, Robertson M, et al. Acute knee dislocation: review of an elusive entity. Curr Probl Diagn Radiol. 2009 Nov-Dec. 38(6):237-50. [Medline].

  85. King JB, Perry DJ, Mourad K, Kumar SJ. Lesions of the patellar ligament. J Bone Joint Surg Br. 1990 Jan. 72(1):46-8. [Medline]. [Full Text].

  86. Kujala UM, Osterman K, Kormano M, et al. Patellofemoral relationships in recurrent patellar dislocation. J Bone Joint Surg Br. 1989 Nov. 71(5):788-92. [Medline]. [Full Text].

  87. Leblanc JM. Patellar complications in total knee arthroplasty. A literature review. Orthop Rev. 1989 Mar. 18(3):296-304. [Medline].

  88. Levine J. Chondromalacia patellae. Physician Sportsmed. 1979. 7:41-9.

  89. Lindberg U, Lysholm J, Gillquist J. The correlation between arthroscopic findings and the patellofemoral pain syndrome. Arthroscopy. 1986. 2(2):103-7. [Medline].

  90. Maenpaa H, Lehto MU. Patellar dislocation has predisposing factors. A roentgenographic study on lateral and tangential views in patients and healthy controls. Knee Surg Sports Traumatol Arthrosc. 1996. 4(4):212-6. [Medline].

  91. Mangine RE, Eifert-Mangine M, Burch D, Becker BL, Farag L. Postoperative management of the patellofemoral patient. J Orthop Sports Phys Ther. 1998 Nov. 28(5):323-35. [Medline].

  92. Miller MD, Hinkin DT, Wisnowski JW. The efficacy of orthotics for anterior knee pain in military trainees. A preliminary report. Am J Knee Surg. 1997 Winter. 10(1):10-3. [Medline].

  93. Miller PR, Klein RM, Teitge RA. Medial dislocation of the patella. Skeletal Radiol. 1991. 20(6):429-31. [Medline].

  94. Moore KL. Clinically Oriented Anatomy. 3rd ed. Baltimore, Md: Lippincott Williams & Wilkins; 1992.

  95. Mow VC, Ateshian GA, Ratcliffe A. Anatomic form and biomechanical properties of articular cartilage of the knee joint. J Biomech Eng. 1991. 113(2):198-207.

  96. Nietosvaara Y, Paukku R, Palmu S, Donell ST. Acute patellar dislocation in children and adolescents. Surgical technique. J Bone Joint Surg Am. 2009 Mar 1. 91 Suppl 2 Pt 1:139-45. [Medline].

  97. Nissen CW, Cullen MC, Hewett TE, Noyes FR. Physical and arthroscopic examination techniques of the patellofemoral joint. J Orthop Sports Phys Ther. 1998 Nov. 28(5):277-85. [Medline].

  98. Nomura E, Inoue M, Kurimura M. Chondral and osteochondral injuries associated with acute patellar dislocation. Arthroscopy. 2003 Sep. 19(7):717-21. [Medline].

  99. Powers CM. Rehabilitation of patellofemoral joint disorders: a critical review. J Orthop Sports Phys Ther. 1998 Nov. 28(5):345-54. [Medline].

  100. Powers CM, Shellock FG, Beering TV, et al. Effect of bracing on patellar kinematics in patients with patellofemoral joint pain. Med Sci Sports Exerc. 1999 Dec. 31(12):1714-20. [Medline].

  101. Rauschning W, Nordesjo LO, Nordgren B. Isokinetic knee extension strength and pain before and after correction of recurrent patellar dislocation. Arch Orthop Trauma Surg. 1983. 102(2):102-6. [Medline].

  102. Sanders TG, Morrison WB, Singleton BA, Miller MD, Cornum KG. Medial patellofemoral ligament injury following acute transient dislocation of the patella: MR findings with surgical correlation in 14 patients. J Comput Assist Tomogr. 2001 Nov-Dec. 25(6):957-62. [Medline].

  103. Schonholtz GJ, Zahn MG, Magee CM. Lateral retinacular release of the patella. Arthroscopy. 1987. 3(4):269-72. [Medline].

  104. Shellock FG. Effect of a patella-stabilizing brace on lateral subluxation of the patella: assessment using kinematic MRI. Am J Knee Surg. 2000 Summer. 13(3):137-42. [Medline].

  105. Shellock FG. Patellofemoral joint abnormalities in athletes: evaluation by kinematic magnetic resonance imaging. Top Magn Reson Imaging. 1991 Sep. 3(4):71-95. [Medline].

  106. Sillanpaa PJ, Peltola E, Mattila VM, et al. 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. 2009 Aug. 37(8):1513-21. [Medline].

  107. Sobhy MH, Mahran MA, Kamel EM. Midterm results of combined patellofemoral and patellotibial ligaments reconstruction in recurrent patellar dislocation. Eur J Orthop Surg Traumatol. 2013 May. 23(4):465-70. [Medline].

  108. Tecklenburg K, Dejour D, Hoser C, Fink C. Bony and cartilaginous anatomy of the patellofemoral joint. Knee Surg Sports Traumatol Arthrosc. 2006 Mar. 14(3):235-40. [Medline].

  109. Wessel LM, Scholz S, Rusch M. Characteristic pattern and management of intra-articular knee lesions in different pediatric age groups. J Pediatr Orthop. 2001 Jan-Feb. 21(1):14-9. [Medline].

  110. White BJ, Sherman OH. Patellofemoral instability. Bull NYU Hosp Jt Dis. 2009. 67(1):22-9. [Medline].

  111. Williams DS 3rd, Green DH, Wurzinger B. Changes in lower extremity movement and power absorption during forefoot striking and barefoot running. Int J Sports Phys Ther. 2012 Oct. 7(5):525-32. [Medline]. [Full Text].

Apprehension sign. The knee is placed at 30° flexion, and lateral pressure is applied. Medial instability results in apprehension by the patient.
Anatomic morphology of patellar insertion into the intercondylar notch.
Muscles influencing patellar biomechanics.
The Q angle can be measured while the patient is standing or while the knee is at 20° of flexion (ie, at neutral), with maximum internal or external rotation of the tibia.
Ligament constraints of the patella.
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