title: Medial patellofemoral ligament: anatomy, injury and treatment in the adolescent knee.
abstract: OBJECTIVE
  Traumatic and nontraumatic patellofemoral instability (PFI) in children and adolescents is a complex problem. It is determined by a large number of mechanical and pathomorphologic conditions, mainly seen in nontraumatic dislocations.
  
  
  RESULTS
  Although conservative treatment with a short immobilization, followed by early passive motion and isometric quadriceps strengthening, can be considered in real traumatic dislocations without any cartilaginous injury, a surgical intervention should be considered in atraumatic cases. As 90% of PFI are nontraumatic and correlated with skeletal deformities, the redislocation rate is reported to be up to 80% after initial conservative treatment. To optimize the results, the causing disorder for PFI has to be considered imperatively. In addition to bony disorder, further risk factors have to be taken into consideration for determining the optimal time for surgery. As biomechanical and clinical studies have shown the importance of the medial patellofemoral complex, especially the medial patellofemoral ligament (MPFL), against patellar lateralization, the reconstruction or minimally invasive double-bundle reconstruction of the MPFL is the main surgical technique to treat PFI in children, as it can be used even in open epiphysial cartilage. Further surgical interventions correcting bone deformities, such as trochleoplasty or tibial tubercle osteotomies addressing lower limb deformities, should be performed after closure of the epiphysial cartilage.
  
  
  CONCLUSIONS
  It is the goal of this overview to explain the pathoanatomy of PFI, the demanding clinical and radiological examinations and treatment options.
authors.affiliation: aDepartment of Trauma Surgery, Trauma Center Murnau, Murnau, Germany bTampere University Hospital, Tampere, Finland cMedical Director of Orthopedics and Sports Medicine, Isar Medical Centre, Munich, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hensler
authors.forename: Petri J
authors.initials: PJ
authors.lastname: Sillanpaa
authors.forename: Philip B
authors.initials: PB
authors.lastname: Schoettle
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000209:etiology / Q000473:pathology / Q000601:surgery*; D007718:Knee Injuries / Q000175:diagnosis / Q000473:pathology / Q000601:surgery*; D008023:Ligaments, Articular / Q000293:injuries / Q000473:pathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D031222:Patellar Dislocation / Q000175:diagnosis / Q000209:etiology / Q000473:pathology / Q000601:surgery; D057071:Patellofemoral Joint / Q000293:injuries / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D012307:Risk Factors