title: Relationship between knee anthropometry and surgical time in total knee arthroplasty in severely and morbidly obese patients: a new prognostic index of surgical difficulty.
abstract: BACKGROUND
  Total knee arthroplasty (TKA) in patients with severe and morbid obesity is one of the current challenges in prosthetic knee surgery. The body mass index (BMI) is used to identify patients who may present difficulties during surgery and postoperative complications. We carried out a prospective study with an initial hypothesis that BMI is not associated with tourniquet time in obese patients undergoing TKA and that some anthropometric parameters may be useful in predicting tourniquet time in severely and morbidly obese patients.
  
  
  METHODS
  One hundred consecutive patients diagnosed with knee osteoarthritis with BMI > or =35 kg/m(2) scheduled for TKA were prospectively studied. Suprapatellar, infrapatellar, and supra/infrapatellar anthropometric indexes were calculated before surgery. The tourniquet time was determined.
  
  
  RESULTS
  The mean BMI was 39.81 kg/m(2) (SD +/- 3.75). A total of 58% of patients were classified as class III obesity (BMI 35-39.99) and 42% as class IV (BMI > or = 40) Mean tourniquet time was 41.67 min (SD +/- 9.26). There was no association between the BMI and tourniquet time. The suprapatellar index was negatively associated with tourniquet time (p < 0.038).
  
  
  CONCLUSIONS
  The BMI is not the only parameter that should be considered in order to identify severely and morbidly obese patients who may have more surgical difficulties during TKA. Preoperative determination of the suprapatellar index helped us to classify these patients according to the morphology of the knee and predicted a longer tourniquet time and, therefore, greater surgical difficulty, in patients with a suprapatellar ratio below 1.6 in this study.
authors.affiliation: Knee Section, Orthopaedic Surgery Department, ICEMEQ, Hospital Clínic, University of Barcelona, Villarroel 170, Barcelona, Spain. llozano@clinic.ub.es
authors.forename: L M
authors.initials: LM
authors.lastname: Lozano
authors.forename: M
authors.initials: M
authors.lastname: Núñez
authors.forename: J M
authors.initials: JM
authors.lastname: Segur
authors.forename: F
authors.initials: F
authors.lastname: Maculé
authors.forename: S
authors.initials: S
authors.lastname: Sastre
authors.forename: E
authors.initials: E
authors.lastname: Núñez
authors.forename: S
authors.initials: S
authors.lastname: Suso
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007431:Intraoperative Complications; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications* / Q000473:pathology / Q000601:surgery; D020370:Osteoarthritis, Knee / Q000150:complications / Q000473:pathology / Q000601:surgery*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D014111:Tourniquets