title: Enduring efficacy of Botulinum toxin type A injection for refractory anterior knee pain.
abstract: OBJECTIVE
  To examine long-term outcomes of Botulinum toxin type A (BoNT-A) injection to vastus lateralis (VL) for refractory anterior knee pain (AKP).
  
  
  METHODS
  Two cohorts (private clinic referrals and previous research participants) injected with BoNT-A for AKP by one neurologist were surveyed retrospectively. Primary outcomes were self-reported benefit, duration of symptom relief, and knee surgery post-injection. Secondary outcomes were changes in utilization of medication/physiotherapy treatment, AKP symptoms and activity limitation.
  
  
  RESULTS
  Overall, average symptom duration was 76 months (SD 98). Responses were available from 46 of 53 private patients. Thirty-eight reported benefit from injection, which was ongoing in 29. Average benefit was 25 months (SD 21). Nine individuals reported symptom recurrence after an average of 14 months (SD 21). Ten had knee surgery post-injection; six of whom had not benefitted from BoNT-A injection. Nineteen of 23 previous research participants were contactable. Initially, all responded favorably to injection. Symptomatic benefit, with an average duration of 44 months (SD 20), persisted in 15. Two subjects proceeded to surgical intervention.
  
  
  CONCLUSIONS
  A single BoNT-A treatment to VL led initially to improved function and relief of knee-related symptoms in 57 of 65 individuals. Improvements were sustained at follow-up, with an average benefit of 34 months (SD 25) post-injection, in 44 of 57 cases.
authors.affiliation: Enrolled in MBBS degree at the Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia, Perth, Western Australia.
authors.forename: Benjamin I
authors.initials: BI
authors.lastname: Silbert
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Singer
authors.forename: Peter L
authors.initials: PL
authors.lastname: Silbert
authors.forename: James T
authors.initials: JT
authors.lastname: Gibbons
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Singer
mesh_terms: D000293:Adolescent; D000328:Adult; D018771:Arthralgia / Q000188:drug therapy*; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D010147:Pain Measurement; D010148:Intractable Pain / Q000188:drug therapy; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A