I have a rod in my femur, so I have a screw right below my hip and one above my knee. Sometimes I find it difficult to sit lotus. It can distract me from practice.
Since your issue is related to mechanical (rod) element, best is avoid that posture.
You can try Vajrasana if that does not hurt or you can sit in any other comfortable posture that your body allows. There is no rule that you have to sit in any specific posture for any yoga activity.
You might find it delightful to know that one can accomplish all levels of meditation even in a chair! Good luck with your practice.
Thank you both so much.