title: Decreased flexion contracture after total knee arthroplasty using Botulinum toxin A: a randomized controlled trial.
abstract: OBJECTIVE
  Flexion contracture after total knee arthroplasty (TKA) can cause significant dissatisfaction. Botulinum toxin A has shown improved extension in patients with spastic flexion contractures after TKA. The purpose of this study was to evaluate whether Botulinum toxin A improves knee extension for any patient with flexion contractures following TKA.
  
  
  METHODS
  A prospective, double-blinded, randomized controlled trial was conducted. Fourteen patients (15 knees), with a flexion contracture (≥10°) one month postoperatively, were randomized to receive either Botulinum toxin A or saline placebo to the affected hamstrings. The subject, surgeon, and administering physiatrist were blinded to the treatment group throughout the study. Subject range of motion (ROM) was evaluated at 1, 6, and 12 months following injection. Differences were tested using mixed-effects regression to control for multiple measurements.
  
  
  RESULTS
  The initial post-operative flexion contracture averaged 19° ± 6° in the Botulinum toxin A group and 13° ± 3° in the saline group. Injections were performed 53 and 57 days after TKA in the Botulinum toxin A and saline groups, respectively. Post-injection extension improved to an average of 8, 5, and 1 degrees for BTX and 4, 2, and 1 degrees for SAL, at 1, 6, and 12 months, respectively, compared to pre-injection extension (p < 0.0001). Improvement in knee extension at 1 year improved 18° ± 7.5° for Botulinum toxin A and 12° ± 2° for saline (p = 0.04). No complications resulted from either injection.
  
  
  CONCLUSIONS
  Patients who received Botulinum toxin A or placebo were able to achieve near full extension one year after surgery. There was a statistically significant improvement in the amount of extension achieved at 1 year with Botulinum toxin A, but this may be of little clinical significance. Since achieving full extension is important for patient function and satisfaction, novel techniques to address this issue deserve special attention.
  
  
  METHODS
  I.
authors: Rothman Institute, 1118 West Baltimore Pike Health Center 4, 3rd Floor Media, Philadelphia, PA, 19063, USA. esmithdoc@yahoo.com.
authors: Eric B
authors: EB
authors: Smith
authors: Sidney Kimmel Medical School at Thomas Jefferson University, Philadelphia, PA, USA.
authors: Karim A
authors: KA
authors: Shafi
authors: Rothman Institute, 1118 West Baltimore Pike Health Center 4, 3rd Floor Media, Philadelphia, PA, 19063, USA.
authors: Ari C
authors: AC
authors: Greis
authors: Rothman Institute, 1118 West Baltimore Pike Health Center 4, 3rd Floor Media, Philadelphia, PA, 19063, USA.
authors: Mitchell G
authors: MG
authors: Maltenfort
authors: Rothman Institute, 1118 West Baltimore Pike Health Center 4, 3rd Floor Media, Philadelphia, PA, 19063, USA.
authors: Antonia F
authors: AF
authors: Chen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D003286:Contracture / Q000188:drug therapy* / Q000209:etiology; D004311:Double-Blind Method; D005260:Female; D000070633:Hamstring Muscles; D006801:Humans; D007273:Injections, Intramuscular; D007719:Knee Joint / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D011446:Prospective Studies; D016059:Range of Motion, Articular
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A
keywords: Arthrofibrosis; Botulinum toxin A; Extension; Flexion contracture; Stiffness; Total knee arthroplasty