use of constained TKR implants in BMI above 40

After seeing a small series of delayed mcl injuries in high flexion, high BMI TKRs and similar issues in published in arthroplasy journal ie; 12 percent in high bmi series in my thoughts and solutions changed

 In heavy individuals  I would use stems and  varus/valgus constraint  devise to

1.To decrease stress at the implant cement and bone interphase

2.To avoid stress on the MCL whose delayed ruptures are reported in high BMI  individual

3.To  ?? reduce anterior subluxation of the tibia in flexion past 70 degrees when the calf and thigh meet and creating an anterior vector ( do we need a anterior and posterior stabilised implant here (food for thougth)

I

used the  Exprt revision  knee implant(DJO) with   vit E poly insert as this is the only constrained system where Vit E poly is available where in one can hopefully reduce wear

 They have a simplified 2 tray revision system which   reduces the complexity of revision surgery Iin OR to reduce errors if  the defects are not huge.