Laminectomy forceps with improved lever mechanism

Laminectomy forceps comprising:

• a cutting unit comprising a fixed beak and a sliding tray slidingly mounted on the fixed beak;
• said fixed beak comprising a stop portion intended to act as stop surface for a cutting portion of the sliding tray;
• an actuation lever to actuate the sliding tray;
• a lever mechanism connected to the actuation lever and to the sliding tray to multiply the force impressed on the actuation lever and transmit the multiplied force to the sliding tray;
• a handle opposite to the actuation lever and joined to an external frame joined to the fixed beak;
• wherein the force multiplicator lever mechanism comprises:
• a first lever shaped as a straight bar and comprising a first end that is hinged to the actuation lever by means of a first pin and a second end that is hinged to the a second lever by means of a second pin;
• a second lever shaped as a straight bar revolvingly mounted around a fulcrum;
• the second lever being connected to the first lever by means of the second pin and to a third lever by means of a third pin;
• a third lever shaped as a straight bar and comprising a first end that is hinged to the second lever by means of the third pin and a second end,
• wherein
• the fulcrum of the second lever is fixed to the external frame, the fulcrum is disposed between a first end of the second lever and a second end of the second lever in such manner to define:
• a first arm between the fulcrum and the first end of the second lever connected to the first level;
• and
• a second arm between the fulcrum and the second end of the second lever that is hinged to the third lever;
• the second end of the third lever is connected by means of a fourth pin to a stem intended to push the sliding tray;
• the first lever and the second lever form a first angle (α) that is obtuse when the actuation lever is in opening position and becomes acute by actuating the actuation lever;
• the second lever and the third lever form a second angle (β) that is acute when the actuation lever is in opening position and becomes obtuse by actuating the actuation lever;
• the obtuse angles are in the range of 95° to 110° and
• the acute angles are in the range of 50° to 70°.