Design and simulation verification of clamping instrument with active variable stiffness for pelvic fracture reduction

BACKGROUND

During the robot-assisted pelvic fracture reduction process, the clamping instrument are subjected to the large reduction force from the robot, resulting in inevitable great stress concentration and deformation of the bone pins, affecting the fracture reduction accuracy.

METHOD

A compact and easily-to-adjust clamping instrument with active variable stiffness is designed. The relationship between the component's elongation and the clamping instrument's deformation and stiffness is derived and calculated. Furthermore, the finite element model of the fixed and the variable stiffness clamping instruments connecting with the injured pelvic musculoskeletal tissue is developed, respectively.

RESULTS

Applying the same reduction force, the deformation of the clamping instrument with variable stiffness is reduced, especially in the elongated state. Moreover, the new clamping instrument meets the strength requirements and makes a better stress distribution.

CONCLUSION

The clamping instrument can achieve stiffness adjustment during the reduction process and will be used for improving the surgery accuracy.

Parallel manipulator robot assisted femoral fracture reduction on traction table

The principle of femoral shaft fracture reduction is to restore its pre-fractured limb length and mechanical axis. The current documented treatment method with traction table reduction does not conform to the quantitative alignment and reduction. There is also a great amount of X-Ray radiation exposure to both surgeon and patient during the procedure. For this reason, we introduced an innovated Parallel Manipulator Robot (PMR) application: A Femoral Shaft Fracture Reduction with Parallel Manipulator Robot on Traction Table. With this application, the quantitative control on fracture reduction and alignment can be achieved and the radiation exposure to both surgeons and patients can be greatly reduced.