Needle holders are surgical instruments used primarily to grasp and guide suturing needles during procedures like wound closure and tissue repair. Their key function is to hold the needle firmly and provide a secure grip, which allows surgeons to maneuver the needle through tissue with precision and stability. They also aid in hemostasis by helping to place sutures for controlling bleeding, and are essential for delicate operations like microsurgery and vascular surgeries.  

Suturing:

The main purpose is to hold the needle securely for precise and accurate stitching of wounds or surgical incisions.

Tissue approximation:

They help in bringing tissue edges together, which is crucial for proper healing.

Hemostasis:

They assist in placing sutures to control bleeding during surgery.

Knot tying:

In some cases, they can also be used for instrumental knotting of the suture.