1. Selection of intramedullary pin: The intramedullary pin with appropriate thickness and length must be selected to give full play to the fixation function. The length of intramedullary nail can be shortened by 4 ~ 6 cm according to the length measured by healthy bone, and the width can be about 65438±0mm smaller than the diameter of the narrowest part of medullary cavity (2mm smaller than femur) shown by X-ray. The more correct way is to fix the intramedullary nail with known width on the same plane of the injured bone or the healthy side bone, and take photos together for comparative measurement. However, these methods are only rough estimates, and it is still advisable to prepare more intramedullary needle supply tables 1 for selection during operation. Intramedullary needle can be directly inserted into the narrow part of medullary cavity during operation, but it is inevitable to insert it forcibly when encountering resistance, so as not to cause bone splitting or difficulty in pulling out. Generally, intramedullary nails with the same diameter or slightly wider should be selected to achieve the maximum elastic fixation of cross section.

Table 1 specifications of commonly used intramedullary nails Bone length (mm) Width (mm) Thickness (mm) Femur 280 ~ 400 7 ~ 12 1.2 Tibia 200 ~ 300 7 ~ 9 1.2 Humerus 200 ~ 250 6. 80 ~ 230 2 ~ 40.8 Radius 654384 0.8 2. The operator should fully estimate the possible difficulties and complications during the operation and prepare the instruments for treatment (such as hacksaw, multiple reamers with different thicknesses, steel wires, etc.). ).