title: Total weight loss associated with increased physical activity after bariatric surgery may increase the need for total joint arthroplasty.
abstract: BACKGROUND
  Retrospectively, our institution noticed an increased number of patients undergoing total joint arthroplasty (TJA) after bariatric surgery. Considering that bariatric surgery is a proven modality to reduce osteoarthritic pain, we sought to identify a reason some patients may later require TJA. The objective of this study was to investigate the hypothesis that rapid or increased weight loss after bariatric surgery may be a risk factor for TJA.
  
  
  METHODS
  Weight loss parameters were retrospectively assessed in 15 bariatric surgery patients who subsequently received a primary TJA and compared with matched bariatric controls.
  
  
  RESULTS
  Patients who required a TJA lost 27.9% more of their body mass index (BMI) compared with controls (P = .049). Furthermore, patients who underwent TJA 25-48 months postbariatric surgery lost 78.2% more of their BMI compared with controls (P<.001). Total knee arthroplasty patients lost 43.9% more of their BMI compared with controls (P = .02), and the difference in BMI change for total hip arthroplasty patients was not significant versus controls.
  
  
  CONCLUSIONS
  These results contradict the tenant that weight loss is universally protective against arthritis and merit larger prospective investigations.
authors.affiliation: Department of Orthopaedics, Boston, Massachusetts.
authors.forename: David
authors.initials: D
authors.lastname: Trofa
authors.affiliation: Department of Orthopaedics, Boston, Massachusetts. Electronic address: esmith@tuftsmedicalcenter.org.
authors.forename: Eric L
authors.initials: EL
authors.lastname: Smith
authors.affiliation: Department of Orthopaedics, Boston, Massachusetts.
authors.forename: Vivek
authors.initials: V
authors.lastname: Shah
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: Scott
authors.initials: S
authors.lastname: Shikora
mesh_terms: D000328:Adult; D019643:Arthroplasty, Replacement / Q000009:adverse effects*; D050110:Bariatric Surgery; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000150:complications* / Q000453:epidemiology; D010003:Osteoarthritis / Q000209:etiology* / Q000601:surgery; D011184:Postoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D015431:Weight Loss
keywords: Bariatric surgery; Rapid weight loss; Total hip arthroplasty; Total knee arthroplasty