Retractable needle medical device for injecting fluid from a pre-filled cartridge

A medical device, comprising:

• a hollow housing having an open rearward end for receiving a cartridge containing fluid, wherein the housing is slidably displaceable within a barrel;
• a needle having a sharpened tip in fluid communication with the cartridge;
• a first lock configured to retain the housing such that the needle is in a projecting position in which the sharpened tip of the needle is exposed for use, wherein the first lock is configured to release the housing due to radial deformation of an actuator substantially without the housing rotating relative to the barrel;
• a second lock configured to releasably retain the needle in a first retracted position in which the sharpened tip of the needle is shielded against inadvertent contact;
• a third lock configured to permanently retain the needle in a second retracted position in which the sharpened tip of the needle is shielded against inadvertent contact, wherein the lock permanently impedes axial displacement of the needle;
• and
• a biasing element biasing the needle rearwardly.

A method for injecting medical fluid, the method comprising:

• providing a medical device that includes a displaceable housing and a barrel, wherein the housing is connected to a needle that defines a sharpened tip;
• piercing a patient with the needle in an extended position;
• injecting fluid from a first cartridge into the patient;
• retracting the needle into the barrel by displacing the housing relative to the barrel while substantially preventing rotation of the housing relative to the barrel, wherein the sharpened tip is shielded against inadvertent contact when the tip is within the barrel;
• releasably locking the needle in a retracted position within the barrel;
• replacing the first cartridge with a second cartridge containing fluid;
• re-extending the needle to the extended position by displacing the housing relative to the barrel while substantially preventing rotation of the housing relative to the barrel such that the needle moves from the extended position to the retracted position and back to the extended position again substantially without rotation of the housing relative to the barrel;
• injecting fluid from the second cartridge into the patient;
• and
• retracting the needle into the barrel a subsequent time by displacing the housing while substantially preventing rotation of the housing relative to the barrel.

A medical device comprising:

• a hollow barrel;
• an inner housing slidably displaceable within the barrel, and having an opening for receiving a cartridge;
• a needle connected to the housing and having a sharpened tip configured to fluidly communicate with the cartridge;
• a plunger operable to expel fluid from the cartridge;
• a first lock configured to retain the housing such that the needle is in a projecting position in which the sharpened tip of the needle is exposed for use, wherein the first lock is configured to release the housing due to radial deformation of an actuator substantially without the housing rotating relative to the barrel;
• a second lock configured to releasably retain the needle in a retracted position in which the sharpened tip of the needle is shielded against inadvertent contact;
• a guide configured to substantially prevent rotation of the housing relative to the barrel as the housing moves from the first lock to the second lock and configured to substantially prevent rotation of the housing relative to the barrel as the housing moves from the second lock to the first lock;
• and
• a biasing element biasing the needle rearwardly.