title: Incidence and long-term follow-up of isolated posterior cruciate ligament tears.
abstract: OBJECTIVE
  Isolated posterior cruciate ligament (PCL) tears are an uncommon injury. The goals of this study are to (1) determine the population-based incidence of isolated PCL tears, (2) compare the occurrence of secondary meniscal tears or arthritis in patients with PCL deficiency to patients without PCL tears, and (3) evaluate factors associated with long-term sequelae among patients with PCL deficiency.
  
  
  METHODS
  This retrospective study included a population-based incidence cohort of 48 patients with new-onset, isolated PCL tears between 1990 and 2010, as well as an age and sex-matched cohort of individuals without PCL tears. A chart review was performed to collect information related to the initial injury, treatment, and outcomes. Subjects were retrospectively followed to determine the development of subsequent meniscal tears, arthritis, or total knee arthroplasty (TKA).
  
  
  RESULTS
  The age- and sex-adjusted annual incidence of isolated, complete PCL tears was 1.8 (95 % CI 1.3, 2.3) per 100,000. During a mean 12.2-year follow-up, patients with isolated PCL tears had a significantly higher likelihood (HR 6.2, 95 % CI 1.8, 21.2) of symptomatic arthritis compared to individuals without PCL tears. The likelihood of subsequent meniscal tears (HR 2.1, 95 % CI 0.4, 10.7) and TKA (HR 3.2, 95 % CI 0.5, 19.6) was more frequent among patients with PCL tears compared to subjects without PCL tears. Older age at injury was significantly associated with future arthritis (P = 0.003) and TKA (P = 0.02).
  
  
  CONCLUSIONS
  Isolated PCL tears remain a rare injury with an estimated annual incidence of 2 per 100,000 persons. Patients with isolated PCL tears have a significantly higher risk of symptomatic arthritis than patients without PCL tears. Older age at injury is associated with a higher risk of arthritis and the need for TKA. The results of this study can be used to educate patients about the natural history of isolated PCL tears and provide a baseline of expectations for the future development of arthritis and subsequent meniscal injury following isolated PCL injury.
  
  
  METHODS
  Retrospective comparative study, Level III.
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA. sanders.thomas@mayo.edu.
authors.forename: Thomas L
authors.identifier: http://orcid.org/0000-0001-7741-9692
authors.initials: TL
authors.lastname: Sanders
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Ayoosh
authors.initials: A
authors.lastname: Pareek
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Barrett
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.|Health Sciences Research, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Hilal Maradit
authors.initials: HM
authors.lastname: Kremers
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Bryan
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Stuart
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Levy
authors.affiliation: Departments of Orthopedic Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Krych
mesh_terms: D000293:Adolescent; D000328:Adult; D019645:Arthroplasty, Replacement, Knee; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007718:Knee Injuries / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016119:Posterior Cruciate Ligament / Q000293:injuries* / Q000601:surgery; D011379:Prognosis; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: Arthritis; Incidence; Meniscal tear; PCL; Posterior cruciate ligament; Total knee arthroplasty