US5431652A — Bone-treating devices and their manufacturing met…

Claim 1

Independent Claim 81 words

Bone-treating devices made of biodegradable polymers having a high-density and a high-orientation along the major axis, which have a density of 1,260 g/cm 3 or more (when measured by the sink and float method) and which possess the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2) (1) B/A≧0.85 (2) wherein A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 2

Dependent Claim 81 words

Bone-treating devices made of biodegradable polymers having a high-density and a high-orientation along the major axis, which have a density of 1,260 g/cm 3 or more (when measured by the sink and float method) and which possess the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2) (1) B/A≧0.85 (2) wherein A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 3

Dependent Claim 18 words

Bone-treating devices as defined in claim 1, which have a density between 1.265 and 1,285 g/cm 3 .

Claim 4

Dependent Claim 53 words

Bone-treating devices as define in claim 1, which have the bending strength and the bending strength-retaining characteristic expressed by the following equations: A≧B≧25 (kgf/mm.sup.2) (1') B/A≧0.90 (2') wherein A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 5

Dependent Claim 30 words

The devices as defined in claim 1, in which lactic acid polymers with a viscosity-average molecular weight of 50,000 or more as a raw material are used as biodegradable polymers.

Claim 6

Dependent Claim 18 words

The devices as defined in claims 4, in which L-lactic acid polymers are used as lactic acid polymers.

Claim 7

Dependent Claim 21 words

The devices as defined in claim 4, in which lactic acid polymers have a viscosity-average molecular weight of 250,000 to 500,000.

Claim 8

Independent Claim 120 words

The method for manufacturing bone-treating devices comprising hydrostatically extruding biodegradable polymers by applying pressure to a pressure medium so as to indirectly extrude the biodegradable polymer at a temperature between the glass transition point and the melting point thereof to produce high-density products in which the molecules of the polymer are oriented along the major axis and which have a density of 1,260 g/cm 3 or more when measured by the sink and float method, and the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2) (1) B/A≧0.85 (2) where A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 9

Independent Claim 120 words

The method for manufacturing bone-treating devices comprising hydrostatically extruding biodegradable polymers by applying pressure to a pressure medium so as to indirectly extrude the biodegradable polymer at a temperature between the glass transition point and the melting point thereof to produce high-density products in which the molecules of the polymer are oriented along the major axis and which have a density of 1,260 g/cm 3 or more when measured by the sink and float method, and the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2) (1) B/A≧0.85 (2) where A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 10

Dependent Claim 20 words

The method as defined in claim 7, wherein the polymer is extruded at an extrusion rate of 4:1 to 15:1.

Claim 11

Dependent Claim 26 words

The method as defined in claim 8, wherein the polymer is extruded at least 2 times to yield a total extrusion ratio of 4:1 to 15:1.

Claim 12

Dependent Claim 17 words

The method as defined in claim 7, in which lactic acid polymers are used as biodegradable polymers.

Claim 13

Independent Claim 18 words

The method as defined in claims 10, in which L-lactic acid polymers are used as lactic acid polymers.

Claim 14

Dependent Claim 26 words

The method as defined in claim 10, in which the temperature and ratio of extrusion for poly-L-lactic acid are 140°±10° C. and 5:1 to 10:1, respectively.

Claim 15

Dependent Claim 55 words

The method as defined in claim 7 wherein the devices have the bending strength and the bending strength-retaining characteristic expressed by the following equations: A≧B≧25 (kgf/mm.sup.2) (1') B/A≧0.90 (2') wherein A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in the phosphate buffer at 37° C.

Claim 16

Dependent Claim 27 words

The method as defined in claim 7, wherein the polymer is extruded at a temperature between the glass transition point and the melting point of the polymer.

Claim 17

Dependent Claim 24 words

The method as defined in claim 14, wherein the polymer is extruded at a temperature slightly lower than the melting point of the polymer.

Claim 18

Independent Claim 137 words

A method for manufacturing bone-treating devices comprising differential pressure extrusion of biodegradable polymers by hydrostatically applying first pressure (P 1 ) in a direction of extrusion and second counter pressure (P 2 ), in which P 1 is larger than P 2 , at a temperature between the glass transition point and the melting point thereof to produce high-density products in which the molecules of the polymer are oriented along the major axis and which have a density of 1,260 g/cm 3 or more when measured by the sink and float method, and the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2) (1) B/A≧0.85 (2) where A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 19

Independent Claim 137 words

A method for manufacturing bone-treating devices comprising differential pressure extrusion of biodegradable polymers by hydrostatically applying first pressure (P 1 ) in a direction of extrusion and second counter pressure (P 2 ), in which P 1 is larger than P 2 , at a temperature between the glass transition point and the melting point thereof to produce high-density products in which the molecules of the polymer are oriented along the major axis and which have a density of 1,260 g/cm 3 or more when measured by the sink and float method, and the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2) (1) B/A≧0.85 (2) where A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 20

Independent Claim 126 words

A method for manufacturing bone-treating devices comprising extruding biodegradable polymers by applying hydrostatical pressure (P) and drawing pressure (F), in which P and F are applied in a direction of extrusion at a temperature between the glass transition point and the melting point thereof to produce high-density products in which the molecules of the polymer are oriented along the major axis and which have a density of 1,260 g/cm 3 or more when measured by the sink and float method, and the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2 ( 1) B/A≧0.85 (2) where A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Claim 21

Independent Claim 126 words

A method for manufacturing bone-treating devices comprising extruding biodegradable polymers by applying hydrostatical pressure (P) and drawing pressure (F), in which P and F are applied in a direction of extrusion at a temperature between the glass transition point and the melting point thereof to produce high-density products in which the molecules of the polymer are oriented along the major axis and which have a density of 1,260 g/cm 3 or more when measured by the sink and float method, and the bending strength and the bending strength-retaining characteristic defined by the following equations: A≧B≧23 (kgf/mm.sup.2 ( 1) B/A≧0.85 (2) where A is the initial bending strength and B is the bending strength after 90-days immersion of the devices in a phosphate buffer at 37° C.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-07-10	1999-01-09	1999-07-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-07-10	2003-01-09	2003-07-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-07-10	2007-01-09	2007-07-11	$7700.00	Window Closed / Lapsed

Bone-treating devices and their manufacturing method

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