Abstract
Objectives
Femoral shaft fracture treatment often results in mal-alignment and the high dosage of radiation exposure. The objective of this study is to develop a Parallel Manipulator Robot (PMR) on traction table to overcome these difficulties so as achieve better alignment for the fractured femur and reduce radiation to both patients and physicians.
Methods
The distal platform of PMR is attached to the central pole on standard traction table by the boot adaptor. A leg model with soft tissue made by Pacific Research Laboratory, Inc. is flexed at the knee with patella on the top. A 2/3 circular ring, with 1/3 open circle down, fixed to the fractured distal femur with one trans-wire and one self-tapping screw, acting as adaptable stirrup fixing scheme. To secure proximal femur, an adapter is assembled on the traction table and fixed on the proximal femur. The distal femur is fixed to the 2/3 circular ring platform of PMR. Surgical planning is performed by first acquiring the bi-planar images from the C-Arm X-ray machine. After simulated fracture on 3-D femoral model is made, proximal and distal segments of the model will be superimposed with background bi-planar images. Finally the pre-fractured length and mechanical axis of 3-D femoral model will be restored. Afterwards, a table of schedule for length adjustments of six struts of PMR is generated. This length adjustment schedule is used to drive the PMR for fractured femur alignment and reduction. When reduction completed, a special designed device is used to fix the reduced femur. Then the PMR is removed from the traction table and the patient can be removed from the traction table.
Results
Eight femoral sawbones model were artificially broken into eight different fracture patterns. All the fracture patterns have characteristics of distal segments overlapping with proximal segments but in the different locations. The operations of reduction were all following the initial tractions. The results showed that the mean errors were 1.31+-0.45mm for axial discrepancies, 2.43+-0.49mm for lateral translations, 2.26+-0.23mm for angulations
Conclusion
Femoral Shaft Fracture Reduction with PMR on traction table has been built with femoral soft tissue model. The experiments had been made on artificially broken femoral sawbone models. The experiments had been proven that such approach is accurate enough for femoral shaft reduction. Further experiments are necessary in order for it to be used clinically.
