Lower limb arthroplasty of the hip and knee are common orthopaedic surgical interventions. These interventions have predominantly been used in the treatment of symptomatic osteoarthritis that has been non-responsive to less invasive therapies. Replacement of the arthritic articular surfaces allows for improved functional and pain outcomes when successful [1].

Globally, population weights and average body mass index (BMI) are rising [2,3]. Evidence suggests that over half of patients undergoing total knee arthroplasty (TKA) are obese [4]. Obesity is a significant risk factor for degenerative joint disease and as a result, a large proportion of patients referred for operative intervention will be overweight [5]. This will likely lead to an increasing requirement for arthroplasty surgery into the future [6]. Debates around preoperative and postoperative weight changes associated with osteoarthritis and arthroplasty are common.

Obesity is a risk factor for post-operative complications in surgery including higher rates of wound infections and wound complications [7]. Outcomes following arthroplasty in obese patients have also shown to be worse [8,9]. These risks can sometimes lead to surgeon reluctance in providing surgical interventions. As a result, significant research has also been carried out investigating pre-operative weight loss techniques up to, and including bariatric surgery [10]. An opportunity for post-operative weight loss following hip or knee arthroplasty could mitigate these operative risks and favour intervention for secondary weight loss benefits amongst other benefits, including reduced pain.

When symptomatic, osteoarthritis of the hip and knee can lead to significant pain and reduced exercise and mobility as a result. A potential cycle of reduced function, reduced mobility and the potential for weight gain ensues. Patients may gain weight when symptomatic due to functional limitations secondary to pain. In theory, reducing pain by surgical means could lead to increased mobility which could lead to weight loss. While weight loss in overweight patients is one of the primary treatments for osteoarthritis, patients often suggest that this is difficult due to significant pain and limited function [11]. Patients often hypothesize that reducing pain and increasing mobility will result in post-operative weight loss. As a result, conflicting patient and surgeon theories can arise.

There has been significant disparity in reported weight changes following hip and knee arthroplasty. While some studies have shown postoperative weight loss and weight gain, many studies have shown that arthroplasty results in maintenance of pre-operative weight [12]. Clarity regarding this is important when considering the long term implications and benefits following a significant surgical intervention. Weight loss following hip or knee arthroplasty could potentially provide significant health improvements and reduce healthcare spending on obesity related comorbidities if successful.

A previous systematic review performed by Inacio et al., in 2013 showed that there insufficient evidence to categorically say whether total hip arthroplasty (THA) or TKA resulted in significant changes [13]. Multiple large studies have been performed in the meantime with the aim of further answering this question. The aim of this study to systematically review the available literature to assess for weight changes following knee and hip arthroplasty given this new evidence. We hypothesize that arthroplasty will not result in any significant weight loss post-operatively based on previous data from Inacio et al., 2013 [13]. To our knowledge, we will be the first study to attempt to address this question since Inacio et al., in 2013 [13].