The Navigation System Of Intramedullary Needle Restoration Based On Three Dimensional Image

Fractures is a relatively common clinical disease seriously affecting human beings' life and health.There are many causes of fractures,such as trauma?traffic accident and so on.With the increase of the types of outdoor sports,sports-related injuries have increased.At the same time,the occurrence of traffic accidents has also increased the number of patients with fractures.More and more people use intramedullary nail fixation to treat fractures.The traditional intramedullary needle fixation method is to insert an intramedullary needle into the patient's broken bone with the guidance of an X-ray film,and then use a guide rod,a sight,and other fixation instruments at the outer end of the intramedullary needle.At last,a bone drill is used to insert the nail into the hole of the intramedullary needle from the installed drilling drill.Doctors and patients are exposed to X-ray radiation.The fixed instruments like guide rod may cause deformation during the connection process,making it difficult for doctors to aim at the exact position.During the operation,doctors also cannot observe the position of the surgical instrument into the broken bone,making it impossible to guide the surgery properly.In order to solve the above problems,the navigation system of intramedullary needle restoration based on three dimensional image was designed.In this system,registration between image space and patient space is the basis of surgical navigation.When setting the registration between the image and the patient,it didn't use the Iterative Closest Point algorithm.Because using the ICP algorithm in registration may cause the local optimal problem.So the wide registration algorithm and the detailed registration algorithm were used.The wide registration algorithm uses a principal component analysis and the detailed registration algorithm is an improved algorithm based on ICP algorithm.It not only improves the accuracy of registration but also solve the local optimal problem.Space three-dimensional positioning equipment were used to track the position information of the positioning ball which was fixed on the surgical instrument and send the information to the image workstation in real-time.The surgical instruments were displayed proportionally in the image workstation.Thus,no matter in the actual space or in the image workstation,if the intramedullary needle moves in one space,it will make the same changes in the other space through the registration.Doctors can observe the position of the intramedullary needle in the image workstation to find the position of the intramedullary needle hole,and then then put the nail into the hole of the intramedullary needle.In the experiment,using a probe plays a role of the bone drill.Distance and angle determination methods were used to accurately find the position of the intramedullary needle hole.Distance determination means that the distance between the probe tip and the central axis of the intramedullary needle hole is smaller than a certain threshold.The angle determination means that the angle between the straight line of the probe and the central axis of the intramedullary needle hole is smaller than a certain threshold.The steel nails were inserted into the exact position of the intramedullary needle hole when both the distance and angle satisfied the conditions.In this paper,the simulation experiments were conducted to verify whether the system meets the clinical requirements for the restoration of the intramedullary needle.The verification result shows that the system meet the requirements of the basic intramedullary needle reconstructive surgery.