title: No clinically meaningful weight changes in a young cohort following total joint arthroplasty at 3-year follow-up.
abstract: BACKGROUND
  Total joint arthroplasty (TJA) is one of the most successful operations. There is little in the literature regarding weight change following TJA, particularly in a young cohort.
  
  
  METHODS
  Retrospective analysis of 181 primary total hip arthroplasty (THA) and 185 primary total knee arthroplasty (TKA) patients was conducted. We reviewed preoperative and post-operative weights and post-operative body mass index at 3 and 6 months, 1 year, 2 and 3 years. We evaluated expected versus actual weight gain, and performed subgroup analyses of obese versus non-obese patients and active duty versus civilian patients. We used a minimal clinically meaningful weight change from baseline of ≥5%.
  
  
  RESULTS
  One hundred and fifty-one (41.3%) patients were active duty military service members with the mean age of 53 ± 11.1 years. In TKA patients, statistically significant differences were found in mean weights at 3 months (-1.8%, P ≤ 0.0001) and 2 years (+1.9%, P = 0.0006). In THA patients, statistically significant weight gains were found at 6 months (+1.1%, P = 0.006). For obese TKA patients, significant weight changes were observed at 3 months (-2.5%, P ≤ 0.0001), and none in the obese THA group. There were no statistical or clinically meaningful weight changes in the non-obese TKA or THA groups. There was a clinically meaningful weight gain in active duty TKA patients at 3 years (5.18%, P = 0.17).
  
  
  CONCLUSIONS
  Despite a theoretical ability to lose weight following TJA, patients maintain their preoperative weight following TJA. We found a clinically meaningful weight gain at 3 years post-operatively only in active duty TKA patients. Overall, however, we found no clinically significant weight changes following TJA at 3-year follow-up.
authors.affiliation: Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, Maryland, USA.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Formby
authors.affiliation: Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, Maryland, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Purcell
authors.affiliation: Department of Surgery, Uniformed Services University of Health Sciences, Bethesda, Maryland, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Baird
authors.affiliation: Department of Surgery, Uniformed Services University of Health Sciences, Bethesda, Maryland, USA.|Department of Regenerative Medicine, Naval Medical Research Center, Silver Spring, Maryland, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Wagner
authors.affiliation: Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, Maryland, USA.
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Goodlett
authors.affiliation: Department of Orthopaedics, Walter Reed National Military Medical Center, Bethesda, Maryland, USA.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Mack
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D012189:Retrospective Studies; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology*
keywords: 
  BMI
  ; total joint arthroplasty; weight change