An automatic injection device for precise cement delivery during osteoporotic bone augmentation

Augmentation of osteoporotic bone with polymethylmethacrylate (PMMA) bone cement has been shown to be effective in reducing the risk of bone fracture. Injection of the highly viscous bone cement, however, is challenging mainly due to high injection forces required to maintain the nominal injection rates. Also, effective placement of the cement requires precise planning and execution. We are developing a surgical workstation for planning and executing proximal femur augmentation. As a crucial part of the framework, we have designed and fabricated a prototype automatic injection device that provides the substantial forces while maintaining the planned injection rates. Design parameters were determined based on the criteria available in the literature and our preliminary tests. Intended features for the device included high injection force capability, precisely controllable injection and ease of use. A number of calibration experiments were performed to ensure that the device meets the intended criteria. The device can be quickly set up before the surgical operation and can operate in manual or automatic placement configurations. The automatic injection device can also be used for a range of other orthopaedic applications involving direct augmentation of the bones or screws fixated in the bones.