Does body mass index affect clinical outcome post-operatively and at five years after primary unilateral total hip replacement performed for osteoarthritis?

Abstract

Studies describing the effect of body mass index (BMI) on the outcome of total hip replacement have been inconclusive and contradictory. We examined the effect of BMI on medium-term outcome in a cohort of 1617 patients who underwent a primary total hip replacement for osteoarthritis. These patients were followed prospectively for five years with the outcomes of dislocation, revision, duration of surgery and deep and superficial infection studied, as well as collecting Harris hip scores (HHS) and Short-Form 36 (SF-36) questionnaires pre-operatively and at review. A multivariate analysis was performed to see whether BMI is an independent predictor of poor outcome. We found that patients with a BMI of ? 35 kg/m(2) have a 4.42 times higher rate of dislocation than those with a BMI < 25 kg/m(2). Increasing BMI is also associated with superficial infection and poorer HHS and SF-36 scores at five years. These trends remain significant even when multivariate analysis adjusts for age, gender, prosthesis, operating consultant, pre-operative HHS and SF-36, and comorbidities including diabetes mellitus, cardiac disease and osteoporosis. Despite the increased risks, the five-year outcome scores indicate that obese patients have much to gain from total hip replacement. Thus total hip replacement should not be withheld from patients solely on the grounds of an elevated BMI. However, longer-term follow-up of this cohort is required to establish whether adverse outcomes become more evident with time.

Surgical Risks and Costs of Care are Greater in Patients Who Are Super Obese and Undergoing THA

“…There is disagreement regarding whether these individuals have greater surgical risks and costs for the episode of care [2,4,6,10] and the magnitude of those risks and costs. Further, there is no established threshold for obesity as defined by BMI in defining increased complications and risks.…”

“…Michalka et al [18] reported on operative time, blood loss, suboptimal implant placement, the surgeons' perception of operative difficulty, and the six-minute walk test. Davis et al [6] studied dislocation, revision, duration of surgery, and deep and superficial infections. Both groups concluded total hip replacement ''should not be withheld'' or that ''obese patients gain similar benefit''.…”

“…Some studies have reported that the risk of postoperative complications after joint arthroplasty in patients who are obese is comparable to the risk in patients who are nonobese as long as their BMI is less than 40 kg/m 2 [1,17]. However, morbid obesity is associated with a higher risk of postoperative complications [6,21,24]. In addition, super obesity (BMI C 50 kg/m 2 ) has been reported to pose an even more substantial risk compared with the risk in patients who are less obese (BMI \ 50 kg/m 2 ) [8,15,23].…”

“…In addition, super obesity (BMI C 50 kg/m 2 ) has been reported to pose an even more substantial risk compared with the risk in patients who are less obese (BMI \ 50 kg/m 2 ) [8,15,23]. However, few peer-reviewed studies have addressed the surgical dilemma regarding whether to perform THA on patients who are morbidly obese or super obese [2,6,16,23].…”

Dual-mobility or Constrained Liners Are More Effective Than Preoperative Bariatric Surgery in Prevention of THA Dislocation

“…When obesity is defined as a body mass index (BMI) greater than 30 kg/m 2 in adults, obesity is recognized as an independent risk factor for postoperative hip dislocation in several studies [2,6,8,15,18,22,28,35]. However, in these patients with obesity, it is not known whether the risk is only in the early postoperative period or if the risk persists several years after surgery.…”