Manual bone cement mixing method
OwnerWilliam M. Murrayinventor
Life of this patent
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Abstract
A method for mixing bone cement by mixing PMMA powder and MMA liquid in a vacuum chamber using a rotary mixer having a pair of spaced mixing arms. The rotary mixer is manually rotated by a gear drive. The arms of the rotary mixer follow continuous paths, each path having a plurality of loops at the wall of the chamber and curved portions extending across the chamber between loops. The arms move through the cement, break bubbles and thoroughly mix the PMMA and MMA. Gas from broken bubbles is vacuum drawn from the mixer by a vacuum source. The vacuum source is deactivated when a vacuum tube is detached from the mixer.
Claims18
The method of mixing bone cement comprising the steps of:
- a) placing dry bone cement powder and bone cement liquid in mixing chamber having a sidewall and a bottom;
- b) positioning a first mixer arm in the chamber with the arm extending from the bottom of the chamber up through the top of the bone cement powder and bone cement liquid in the chamber;
- c) moving the mixer arm repetitively along a first continuous path in the chamber, the path including a plurality of loops located adjacent the chamber sidewall and portions extending across the chamber and joining adjacent loops to mix the powder and liquid together and form a body of viscous bone cement in the chamber, sweeping the arm sufficiently close past the sidewall at each loop to mix cement and liquid adhered to the arm and to the sidewall with the body of cement, and passing the arm sufficiently close to gas bubbles in the bone cement adjacent the path to break the gas bubbles;
- and
- d) vacuum flowing the released gas from broken bubbles up and out of the body of bone cement.
The method of mixing bone cement using a bone cement mixing system wherein the system includes a bone cement mixing device having a housing, a mixing chamber with a bottom and a sidewall within the housing, a vacuum tube attachment fitting on the housing and a mixer having a mixing arm extending into the mixing chamber, a vacuum source located away from the mixing device, the vacuum source having a pump with a pump inlet, and a vacuum tube having a first end connected to the attachment fitting and a second end connected to the pump inlet, said method comprising the steps of:
- a) placing dry bone cement powder and bone cement liquid in the mixing chamber;
- b) positioning the arm in the chamber, with the arm extending from the bottom of the chamber up through the top of the bone cement powder and liquid in the mixing chamber;
- c) closing the chamber;
- d) actuating the vacuum source to reduce the pressure in the mixing chamber;
- e) moving the mixer arm repetitively along a continuous path in the chamber, to mix the powder and liquid and form a bone cement body and to break gas bubbles in the bone cement body;
- f) flowing the released gas from broken bubbles out of the cement body and away from the mixing chamber through the vacuum tube and pump;
- g) removing the vacuum tube from the attachment fitting after mixing is completed;
- and
- h) sensing removal of the vacuum tube from the fitting and then immediately shutting down the vacuum pump.
Dependencies are inferred from the claim text.