BMI and THA- Association with Patient Satisfaction and Pain and Function
Moderate strength evidence supports that obese patients with symptomatic osteoarthritis of the hip, when compared to non-obese patients, may achieve lower absolute outcome scores but a similar level of patient satisfaction and relative improvement in pain and function after total hip arthroplasty.


There are four moderate quality studies that support the existence of lower clinical scores in obese patients with mild variation in the cutoff points that define obesity (Yeung et al; BMI>30, Stevens et al; BMI>30, Davis et al; BMI >35, Judge et al; BMI >30).  These results are supported by two low quality studies (McCalden et al; BMI>30, Jackson et al; BMI>30).  Similar improvements in clinical scores between obese and non-obese patients are supported by one moderate quality study (Judge et al) and two low quality studies (Bennett et al; BMI>40, McCalden et al). 

Similarities between obese and non-obese patient satisfaction with total hip replacement are supported by one moderate quality study (Yeung et al) and one low quality study (Villalobos et al; BMI>28). 

One moderate quality study identifies a higher incidence of post-operative dislocation and superficial wound infection in obese patients (Davis et al; BMI>35).  A low quality study reported a higher operative blood loss in obese patients (Bowditch et al; BMI>30). 

Most of the included studies used a BMI level >30 to define obesity and for use as a comparison with lower ranges.  This relatively low cutoff may mask some more dramatic differences in complications and outcomes at the higher levels, such as 40-50 and >50.  In addition, BMI may not be a specific enough index to define the proportionality and distribution of adipose tissue at surgical sites.