Coaxial incisional full-core biopsy needle
Among other things, there are disclosed embodiments of full-core biopsy needles having an outer needle component and a middle cannula through a lumen in the outer component, through which a mandrel may be placed. The outer component includes an internal boss that reduces its internal diameter, and the cannula includes fingers that extend distally. When the needle is inserted for biopsy, tissue enters the outer component and cannula. Moving the cannula forward causes the fingers to engage a surface of the internal boss, resulting in the fingers curving into the tissue. The fingers pinch the tissue while reducing or eliminating compression of the sample to provide an easier removal of the tissue from adjacent tissue, as well as providing a block or backstop keeping the tissue within the needle. Gaps are provided between the fingers to further reduce damage to the tissue sample.
1. A full-core biopsy needle, comprising:
an outer tubular component having a body portion, a transition portion, and a tip portion, said body portion having a substantially constant inner and outer diameter, said transition portion curving inward from said body portion inner and outer diameter and forming an external rounded surface and an internal boss, said tip portion having a constant inner diameter that is smaller than said body portion inner diameter and an outer surface that tapers so that said tip has a first thickness adjacent to the transition portion and a distal edge, said outer component having a lumen through said body portion, said transition portion and said tip portion; and
a cannula within said lumen of said outer component and having a proximal portion and a distal portion, said proximal portion having substantially constant inner and outer diameters, said distal portion having at least a first and second finger separated by a substantially elliptical gap,
wherein said component and said cannula have a first relative position with said fingers proximal of said boss, and said cannula and said component being adapted to be moved with respect to each other into a second relative position, said second relative position being the limit of possible distal location of said cannula with respect to said component and being a position in which at least said first and second fingers are deflected inward by said boss, wherein in said second relative position at least a portion of said first and second fingers point toward each other but do not close the entirety of said gap.
2. The needle of claim 1 , wherein in said second relative position said fingers do not contact each other.
3. The needle of claim 2 , wherein said cannula has at least four fingers equidistantly spaced around said cannula.
4. The needle of claim 3 , wherein said boss is substantially perpendicular to the longitudinal axis of said outer component, and said boss forces said fingers in a direction substantially perpendicular to the longitudinal axis.
5. The needle of claim 4 , wherein said inner diameter of said outer component is surrounded by a wall, and said wall curves into said boss.
6. The needle of claim 4 , wherein said fingers each have a distal end, and wherein force is applied by said boss on said fingers initially solely at said distal end.
7. The needle of claim 5 , wherein said inward deflection of said fingers does not compress tissue within said fingers around the whole diameter of such tissue.
8. The needle of claim 7 , wherein said fingers each have a distal end edge, and substantially all compression on tissue within said fingers is exerted by said distal end edges.