They're replacements. It's what happens when you survive an offensive grenade detonation rather close to your face:
Dang this is close to what I pictured for Jade as I played her the third time!
She was blasted out of her Mech and survived, but lost her left eye, left arm at the elbow, left leg just above the knee. She was fitted with Myomer replacements because she saved the life 3 Leaders of the Inner Sphere, and Phalean Ward. She fought a rouge Crusader Clan Warrior from Smoke Jaguar, intent on disrupting talks to allow the Wolves in Exile to have a planet in the Lyran Alliance. Her last act in the fight was to run her mechh into the Timber Wolf, she was in a refit Wolfhound!
She was called the Iron B**** Wolf by those she crossed and survived, to fight her again! She died in a mech under fire by a full Heavy Lance! Two head shots to the mech, AC/20 and a Medium Pulse Laser. Fusion engine went critical and nothing was found of her!