title: The Influence of Muscle Weakness on the Association Between Obesity and Inpatient Recovery From Total Hip Arthroplasty.
abstract: There is ongoing discussion about whether preoperative obesity is negatively associated with inpatient outcomes of total hip arthroplasty (THA). The aim was to investigate the interaction between obesity and muscle strength and the association with postoperative inpatient recovery after THA.
  
  
  
  Preoperative obesity (body mass index [BMI] >30 kg/m2) and muscle weakness (hand grip strength <20 kg for woman and <30 kg for men) were measured about 6 weeks before THA. Patients with a BMI <18.5 kg/m2were excluded. Outcomes were delayed inpatient recovery of activities (>2 days to reach independence of walking) and prolonged length of hospital stay (LOS, >4 days and/or discharge to extended rehabilitation). Univariate and multivariable regression analyses with the independent variables muscle weakness and obesity, and the interaction between obesity and muscle weakness, were performed and corrected for possible confounders.
  
  
  
  Two hundred and ninety-seven patients were included, 54 (18%) of whom were obese and 21 (7%) who also had muscle weakness. Obesity was not significantly associated with prolonged LOS (odds ratio [OR] 1.36, 95% confidence interval [CI] 0.75-2.47) or prolonged recovery of activities (OR 1.77, 95% CI 0.98-3.22), but the combination of obesity and weakness was significantly associated with prolonged LOS (OR 3.59, 95% CI 1.09-11.89) and prolonged recovery of activities (OR 6.21, 95% CI 1.64-23.65).
  
  
  
  Obesity is associated with inpatient recovery after THA only in patients with muscle weakness. The results of this study suggest that we should measure muscle strength in addition to BMI (or body composition) to identify patients at risk of prolonged LOS.
authors.affiliation: Department of Physical Therapy, Gelderse Vallei Hospital, Ede, The Netherlands; Department of Epidemiology, Faculty of Health, Medicine and Life Sciences, School for Public Health and Primary Care (CAPHRI), Maastricht University, Maastricht, The Netherlands.
authors.forename: Ellen
authors.initials: E
authors.lastname: Oosting
authors.affiliation: Radboud University Medical Center, Radboud Institute for Health Sciences, IQ healthcare, Nijmegen, The Netherlands.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Hoogeboom
authors.affiliation: Department of Physical Therapy, Gelderse Vallei Hospital, Ede, The Netherlands.
authors.forename: Jaap J
authors.initials: JJ
authors.lastname: Dronkers
authors.affiliation: Gelderse Vallei Hospital, Research Unit, Ede, The Netherlands.
authors.forename: Marlieke
authors.initials: M
authors.lastname: Visser
authors.affiliation: Radboud University Medical Center, Radboud Institute for Health Sciences, IQ healthcare, Nijmegen, The Netherlands.
authors.forename: Reinier P
authors.initials: RP
authors.lastname: Akkermans
authors.affiliation: Department of Epidemiology, Faculty of Health, Medicine and Life Sciences, School for Public Health and Primary Care (CAPHRI), Maastricht University, Maastricht, The Netherlands; Top Sector Life Sciences & Health, The Hague, The Netherlands.
authors.forename: Nico L U
authors.initials: NLU
authors.lastname: van Meeteren
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000706:statistics & numerical data*; D015992:Body Mass Index; D005260:Female; D018737:Hand Strength; D006801:Humans; D007297:Inpatients; D007902:Length of Stay / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018908:Muscle Weakness / Q000150:complications*; D009765:Obesity / Q000150:complications*; D016017:Odds Ratio; D010351:Patient Discharge; D020127:Recovery of Function; D016138:Walking
keywords: body mass index; hip arthroplasty; length of stay; muscle strength; risk assessment