Medical titanium alloy bone nail plays a key supporting and fixing role in orthopedic surgery, and its thread design is exquisite and directly related to the success of the operation and the patient's rehabilitation effect. There are many scientific considerations behind it.
From the perspective of fixation stability, the pitch design of the thread is very critical. Different bone parts are subjected to different forces. For example, the long bone shaft needs to withstand large tensile and torsional forces. The bone screw thread usually adopts a dense pitch, which can be deeply embedded in the bone like a tightly meshed gear, providing strong grip to prevent the bone screw from loosening and shifting; in areas rich in cancellous bone, such as vertebral bodies, excessive pitch is prone to bone damage. Appropriate sparse pitch can reduce damage to the trabecular structure while ensuring fixation.
The thread depth should not be ignored either. Too shallow threads are difficult to provide sufficient friction and cannot be fixed firmly; too deep threads may weaken the strength of the bone screw itself and easily cause local stress concentration in the bone. For load-bearing bones, such as the femur, moderately deep threads need to be designed to counteract the pressure brought by the body weight, ensure that the fracture ends are closely connected, and promote healing.
The shape of the thread is also particular. The common triangular thread, with its sharp tooth edge, can effectively cut into the bone and enhance the anchoring effect; while the rectangular thread, although with a large contact area, has unique advantages in the repair of periarticular fractures with extremely high stability requirements and complex forces, and can evenly disperse the load and reduce the risk of fatigue fracture of the bone screw.
The self-tapping design is a highlight of modern bone screw threads. For some complex fracture sites that are difficult to pre-drill, the self-tapping thread can cut the bone by itself during implantation and screw in smoothly, reducing surgical steps and trauma, shortening the operation time, and striving for a better prognosis for patients.
In addition, in order to adapt to the individual differences of different patients, the thread design also considers the combination of universality and personalization. The standardized basic thread parameters can meet most routine cases, while reserving a certain amount of adjustment space. Doctors can flexibly choose or fine-tune according to the patient's bone density, age, fracture type, etc. to achieve precision medicine.
In short, the thread design of the medical titanium alloy bone nail, through the fine carving of pitch, depth, shape, self-tapping and other aspects, takes into account the mechanical principles, human bone characteristics and clinical needs, and provides a solid guarantee for bone repair.
