A study published in The Journal of Bone & Joint Surgery found that employing a cementless rather than a cemented technique to implant the implant improves long-term outcomes for patients with higher BMI who are getting unicompartmental or "partial" knee replacements (UKR). Further, 10-year rates of revision surgery are lower with cementless UKR when compared to cemented UKR.

5,220 patients getting UKR between 2004 and 2018 were included in the study. The same kind of implant was used for every treatment, whether it was cemented or not.

Based on their body weight and height, patients were divided into three BMI categories: 18.5 to 25 kg/m2, 25 to 30 kg/m2, and 30 kg/m2 or higher. Across BMI groups, the results of a ten-year follow-up for cemented and cementless UKR were compared.

The 10-year implant survival rate for cemented and cementless UKR was 90.1% and 92.8%, respectively. The revision rate for individuals who underwent cemented UKR increased with Obesity. Patients with a BMI of 18.5 to 25 had a revision rate per 100 component years of 0.92, compared to 1.15 for patients with a BMI of 25 to 30 and 1.31 for those with a BMI of 30 or above.

The cementless approach had higher implant survival rates in the higher-BMI groups, with rates of 88.5% versus 93.3% in the BMI 25 to 30 groups and 90.7% versus 91.8% in the BMI 30 and higher group. The incidence of surgical and medical complications was comparable across the two methods.

Also, compared to the BMI 18.5 to 25 groups, the revision risk for cementless UKR was generally about 40% lower in the BMI 25 to 30 groups and 25% lower in the BMI 30 and higher group. 

The authors thus conclude that cementless fixation may be more advantageous than cemented fixation in patients with [higher-BMI] conditions, particularly given the increased prevalence of higher BMIs in the general population.

(Source: https://theprint.in/health/bmi-affects-long-term-outcomes-of-partial-knee-arthroplasty-study-2/1429863/)