title: Incidence of knee dislocation and concomitant vascular injury requiring surgery: a nationwide study.
abstract: BACKGROUND
  Acute knee (tibiofemoral joint) dislocation is a serious knee injury, although population-based numbers and incidence rates of knee dislocation with or without concomitant vascular injury are unknown.
  
  
  METHODS
  The study covered the whole adult population of 4 million persons (aged ≥ 18 years) in Finland during the 11-year period from January 1, 1998, to December 31, 2011. Data on hospitalization caused by acute knee dislocations and concomitant vascular injuries requiring operative treatment were obtained from the nationwide National Hospital Discharge Registry.
  
  
  RESULTS
  During the 14-year study period, a total of 837 patients with knee dislocation diagnosis were hospitalized in Finland. The highest incidence rates in men were in persons aged 18 years to 29 years (incidence, 29 per 1 million person-years in 2011), and the incidence decreased by age, while in women, this incidence was rather similar in all age groups. The most common injury mechanism of knee dislocation was low-energy fall at the same level (46%). The median length of hospital stay was 2 days (range, 1-109 days). In 107 cases (13%), knee dislocation required immediate open (69 cases) or closed (38 cases) reduction in the operating room. Popliteal artery injury requiring acute surgical intervention was found in 13 patients (1.6%), and amputation at the level above the tibiofemoral joint was performed for one patient (0.1%).
  
  
  CONCLUSIONS
  This is the first study describing the population-based incidence of acute knee dislocation. Men aged 18 years to 29 years had the highest incidence rates. Half of the injuries were low-energy trauma. Popliteal artery injury requiring surgical intervention was a rare concomitant injury, but when present, the injury required immediate surgical repair to avoid dramatic consequences.
  
  
  METHODS
  Nationwide epidemiologic study, level I.
authors.affiliation: From the Division of Orthopaedics and Traumatology (P.J.S., P.K., V.M.M.), Department of Trauma, Musculoskeletal Surgery and Rehabilitation, Tampere University Hospital; Injury & Osteoporosis Research Center (P.K., S.T.N.), UKK Institute for Health Promotion Research; and Medical School (P.K., V.M.M.), University of Tampere, Tampere, Finland; and Department of Clinical Science, Intervention and Technology (C.R., L.F.T., V.M.M.), and Division of Orthopedics and Biotechnology (C.R., L.F.T., V.M.M.), Karolinska Institutet; and Department of Orthopedics (C.R., L.F.T., V.M.M.), Karolinska University Hospital, Huddinge, Sweden.
authors.forename: Petri J
authors.initials: PJ
authors.lastname: Sillanpää
authors.forename: Pekka
authors.initials: P
authors.lastname: Kannus
authors.forename: Seppo T
authors.initials: ST
authors.lastname: Niemi
authors.forename: Christer
authors.initials: C
authors.lastname: Rolf
authors.forename: Li
authors.initials: L
authors.lastname: Felländer-Tsai
authors.forename: Ville M
authors.initials: VM
authors.lastname: Mattila
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005387:Finland / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D031221:Knee Dislocation / Q000150:complications / Q000453:epidemiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011150:Popliteal Artery / Q000293:injuries / Q000601:surgery; D012737:Sex Factors; D057772:Vascular System Injuries / Q000453:epidemiology* / Q000209:etiology / Q000601:surgery; D055815:Young Adult