title: Preoperative flexion does not influence postoperative flexion after rotating-platform total knee arthroplasty.
abstract: OBJECTIVE
  Preoperative range of motion (ROM) has been regarded as one of the most important factors in predicting postoperative ROM following total knee arthroplasty (TKA). Mobile-bearing TKA designs have been suggested to possibly improve the knee kinematics compared to fixed-bearing designs. The purpose of this study was to examine the difference in postoperative flexion as a function of preoperative flexion in a consecutive series of TKAs done using a posterior-stabilized rotating-platform prosthesis.
  
  
  METHODS
  ROM was assessed in 153 consecutive TKAs done using a rotating-platform posterior cruciate-substituting design. Patients were divided into two groups based on their preoperative ROM (Group 1 < 95°, Group 2 > 95°). The Knee Society Score (KSS) and ROM were assessed preoperatively, 3 months and 12 months postoperatively.
  
  
  RESULTS
  There was no difference in flexion 12 months after surgery between groups (mean 120° and 123°, respectively. n.s.). After 3 month follow-up, no increase in ROM was experienced by either group. Patients in Group 1 experienced significantly greater increases in both ROM (p < 0.001) and KSS (p < 0.05). There was no difference in the KSS at 12 months after surgery between groups.
  
  
  CONCLUSIONS
  In this series of patients undergoing TKA with a rotating-platform prosthesis, the preoperative ROM was not predictive of the postoperative ROM. Patients with stiff knees preoperatively may benefit from a mobile-bearing design prosthesis.
authors: Department of Orthopedic Surgery, UT Southwestern Medical Center, 1801 Inwood Rd, Dallas, TX, 75235, USA, rdrussell25@gmail.com.
authors: Robert D
authors: RD
authors: Russell
authors: Michael H
authors: MH
authors: Huo
authors: Leslie
authors: L
authors: de Jong
authors: Richard E
authors: RE
authors: Jones
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology*; D016896:Treatment Outcome