September 04, 2012
2 min read

Patients with high BMI show similar improvements in patient-reported outcomes after TKA

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

Researchers from the United Kingdom have reported similar improvements in patient-reported outcomes after elective total knee arthroplasty regardless of patient body mass index, according to a recent study published in the Journal of Bone & Joint Surgery.

Paul N. Baker, MBBS, MSc, FRCS(Tr&Orth), and colleagues analyzed patient-reported outcome measures of 13,673 primary total knee arthroplasty (TKA) procedures from the National Joint Registry preoperatively and 6 months postoperatively. Patients were divided into three groups based on body mass index (BMI). Obese patients in the group with a BMI between 40 and 60 kg/m² had similar Oxford Knee Score, EuroQol 5D index and EuroQol 5D VAS scores postoperatively compared to patients with a BMI between 15 and 24.9 kg/m², according to the abstract.

“Patients achieve equivalent improvements in knee function and general health irrespective of their preoperative BMI,” Baker told ORTHOPEDICS TODAY. “Obese patients gain as much benefit from knee replacement as patients with a ‘normal’ BMI, even if they do not end up at a similar postoperative level. Accordingly, we feel that the obese should not be excluded from the benefit experienced by their fellow patients with lower BMI from undergoing total knee replacement.”

Although patient-reported outcomes in the group with the highest BMI were similar, the group had significantly higher wound complications than the patients with “normal” BMI, Baker and colleagues noted. The study comes as a response to recent legislation in the United Kingdom that would limit access to total knee arthroplasty (TKA) procedures for patients with a BMI > 35 kg/m², according to Baker.


“The current situation in the UK is that the responsibility for health budgeting has devolved to the primary care physicians and their associated primary health care trusts. From the money allocated to them, they are responsible for purchasing services from hospitals for their patients,” Baker said. “Certain health care trusts have refused to pay for knee arthroplasty procedures in patients above specific BMI thresholds due to a perceived reduction in risk/benefit in this group. Our argument is that these thresholds are completely arbitrary and lack any evidence to support their use.”


Baker P, Petheram T, Jameson S, et al. The association between body mass index and the outcomes of total knee arthroplasty. J Bone Joint Surg Am. 2012; Aug 15;94(16):1501-1508. doi:10.2106/JBJS.K.01180.