In the practice of diagnostic medicine, it is often necessary or desirable to perform a biopsy, or to sample selected tissue from a living patient for medical evaluation. Cytological and histological studies of the biopsy sample can then be performed as an aid to the diagnosis and treatment of disease. Biopsies can be useful in diagnosing and treating various forms of cancer, as well as other diseases in which a localized area of affected tissue can be identified.
Biopsies are routinely performed on tissue using a needle set, which typically includes an inner needle/stylet with a pointed tip and an aperture/notch defined near its distal end. The stylet is slidably disposed within an outer cannula so that the notch can be alternately exposed or covered. Typically, a hub is connected to the proximal end of each needle. Such needle sets are used with or incorporated in various forms of biopsy devices, such as the single action and double action biopsy devices.
Currently, there are several soft tissue biopsy devices which are classified as Spring Loaded Core biopsy devices. These all share the characteristics of employing springs to create force and movement in needle cannulas axially to selectively remove a sample of the tissue. These devices are required to have the springs loaded, or armed, manually to compress and lock the springs in a compressed state to prepare for actuating the device. As the device is actuated the cannula moves rapidly forward to cut through tissue adjacent to the needle and contain it within the cannula until it is retrieved by the clinician.
Many of the current devices available are deficient in that they are difficult for users to arm and actuate the device and otherwise use the device due to ergonomic factors. For example it is highly desired for the user (usually a physician) to arm the device using a single hand since the other hand is frequently needed to hold other devices. Many current devices cannot be armed easily with a single hand. In addition, many users with smaller than average hands may not be able to arm devices designed for larger hands and also may not be able to arm the device with one hand. Many of the devices are designed so that a single finger is used to arm the device which can be difficult and to do because of the force required. Since the action of arming the device is the same action required to withdraw the outer cannula to access the excised tissue sample, the “arming motion” is done three times per sample (twice to arm the device and once to access the excised tissue sample). When the arming motion cannot be done with a single hand or without difficulty, it presents a significant challenge to the user during the medical procedure. Other devices require compression of elements with the fingers in an extended state which makes it difficult because it is not possible to generate as much force in an extended state as it is with the hand un-extended (e.g. with the hand held in a “C” shape). Some devices have arming features which spring forward and may hit and pinch parts of the hand or patient. In addition, it may be advantageous to arm the device using other surfaces besides the hand and use the muscles of the arm instead to more easily compress the springs.
Another issue is the inability to actuate (i.e., fire) the device easily in-use. Some devices have buttons that cannot be reached easily or require a motion that may disturb the placement of the device which may decrease accuracy of the tissue targeting. The actuation button can be difficult to depress due to the location of the button and/or the force required. In addition it is often desired to have the ability to acquire the tissue in two distinct steps for safety and efficacy reasons. In this case two or more buttons may be needed. Current devices have buttons that may be mistaken from each other due to similar shape and/or position. Current actuation buttons may be unintentionally depressed during handling because they are protruding and can be depressed with pressure coming from unintended contact with a hand surface and/or can be depressed easily with low force. A misfire can be unsafe or compromise the acquisition of tissue.
Current spring loaded core biopsy devices have spring loaded members which propel the needle element forward. The members are stopped when they impact a flat, rigid surface in the device casing by design. This controls the stroke and final position of the needle elements. Although this is effective in positioning and stopping the needle at the desired location, it results in the energy from the needle impact being converted to sound energy which is propagated to the casing of the device. This sound can be relatively loud and often startling to the patient. Most devices make a loud snap noise when actuated which can be startling to the patient who may already be in a distressed state due to the procedure. If the patient is startled not only is there the anxiety involved, but if the patient moves as a result of being startled, the safety and accuracy of the procedure may be affected.
Current devices may be configured so that the tissue aperture is oriented in a position that is not optimized for how the device is usually held. Many users will hold the device so that their hands are in a neutral position. In this position the thumb is on the side of the device in position to depress the button to actuate the device. When held in this position, the aperture opening is preferred to be facing up by many physicians; many devices have the aperture open to the horizontal plane while held in this position.
Needle axial concentricity to hand piece is yet another issue. Current devices have a needle which is asymmetric to the hand piece axis. This forces the operator to make an unnatural eccentric rotation of the wrist during positioning and acquisition of tissue to maintain the intended, centered position of the needle.
Arming feature design is still another issue. Current devices have arming features that protrude laterally external to the device. These features interfere with the patient's body during procedures causing discomfort and a limited range of motion.
Further, some current devices do not have a needle gauge size color indication for the operator to easily select or confirm proper needle size for the procedure.