title: Pigmented villonodular synovitis: a crowdsourcing study of two hundred and seventy two patients.
abstract: We aimed to ascertain the feasibility of crowdsourcing via Facebook for medical research purposes; by investigating surgical, oncological and functional outcome and quality-of-life (QOL) in patients with pigmented villonodular synovitis (PVNS) enrolled in a Facebook community (1112 members).
  
  
  
  Patients completed online open surveys on demographics, surgery and clinical outcomes (group 1); and patient-reported outcome measures (PROMs) including knee-injury osteoarthritis outcome score (KOOS), hip-disability osteoarthritis outcome score (HOOS), Toronto extremity salvage score (TESS) and SF-36 (group 2). Mean follow-up was 70 months (12-374). Consistency checks were performed with Cohen's kappa statistic for intra-rater agreement.
  
  
  
  The first survey was completed by 272 patients (group 1) and 72 patients completed the second (group 2). In group 1, recurrence-rate was 58 % (69/118) after arthroscopic, 36 % (35/97) after open and 50 % (5/10) after combined synovectomy (p = 0.003). In group 2, recurrence-rate was 67 % (26/39) after arthroscopic and 51 % (17/33) after open synovectomy (p = 0.19). Recurrence-risk was increased for diffuse disease (OR = 16; 95%CI = 3.2-85; p < 0.001). Mean function and QOL did not differ after arthroscopic or open synovectomy: KOOS 49 vs. 58 (p = 0.24), HOOS 62 vs. 53 (p = 0.56), TESS 78 vs. 82 (p = 0.86), SF-36 61 vs. 66 (p = 0.41). Cohen's kappa statistic for intra-rater agreement was good to outstanding (κ = 0.68-0.95; p < 0.001).
  
  
  
  Local recurrence-risk was higher for diffuse-type disease and arthroscopic synovectomy. Functional outcome and QOL were comparable for both types of surgery. Gathering data via crowdsourcing seems a promising and innovative way of evaluating rare diseases including PVNS.
authors.affiliation: Orthopaedic Surgery, Leiden University Medical Centre, Postzone J11-R70, PO Box 9600, 2300 RC, Leiden, The Netherlands. lvanderheijden@lumc.nl.
authors.forename: Lizz
authors.initials: L
authors.lastname: van der Heijden
authors.affiliation: Leiden University Medical Centre, Postzone J11-R70, PO Box 9600, 2300 RC, Leiden, The Netherlands.
authors.forename: Sheila R
authors.initials: SR
authors.lastname: Piner
authors.affiliation: Orthopaedic Surgery, Leiden University Medical Centre, Postzone J11-R70, PO Box 9600, 2300 RC, Leiden, The Netherlands.
authors.forename: Michiel Adrianus Josephus
authors.initials: MA
authors.lastname: van de Sande
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001182:Arthroscopy; D002648:Child; D063045:Crowdsourcing; D005240:Feasibility Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000601:surgery*; D010003:Osteoarthritis / Q000601:surgery; D011788:Quality of Life; D020127:Recovery of Function; D061108:Social Media; D000074402:Synovectomy / Q000379:methods; D013586:Synovitis, Pigmented Villonodular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D055815:Young Adult
keywords: Crowdsourcing; Diffuse-type giant cell tumor; Facebook; Functional outcome; PVNS; Pigmented villonodular synovitis; Quality of life