Injectable Polyurethane for Vertebroplasty and Kyphoplasty

Compression fractures can be caused by various conditions, including osteoporosis and tumors. Vertebroplasty and Kyphoplasty are minimally invasive surgical procedures that attempt to relieve the pain, loss of height, and hunched or stooped posture induced by vertebral compression fractures.  Both procedures use bone cement to stabilize the bone affected by the fracture.  Currently, PMMA is used in both Vertebroplasty and Kyphoplasty.  Although approved by the FDA, it is not ideal for these procedures.  The exothermic polymerization of PMMA can cause thermal necrosis of neural tissue. PMMA also has a significantly higher elastic modulus than that of trabecular bone, which may lead to fractures in adjacent vertebrae. PU was examined as a potential material for use in Vertebroplasty and Kyphoplasty. PU consists of a hard segment and a soft segment.  MDI was chosen as the hard segment due to its ability to provide higher siffness, mechanical strength, and modulus to the polymer. The soft segment, PTMO, is ideal because itprovides flexibility and softness.  It is our aim to create an injectable PU cement with an elastic modulus closer to that of trabecular bone, and thereby provide an alternative to PMMA for Vertebroplasty and Kyphoplasty procedures.