Absorbable bone fixation device

Claim 2

A process of forming a high molecular weight polylactide polymer capable of being used as a resorbable bone fixation device comprising: polymerizing L(-)lactide monomer in an inert atmosphere in the presence of a catalyst, said catalyst being present in a monomer to catalyst ratio of from 1000 to 300,000, the polymerization being conducted at a temperature of from 105°C to 170°C, the temperature and monomer to catalyst ratio being selected to fall within the curve A of Figure 1 to form a polymer having an unreacted monomer content of less than 2% and an inherent viscosity in chloroform of between 4.5 and 10.

Claim 3

The process of Claim 1 in which the temperature of polymerization and the monomer to catalyst ratio are selected to fall within curve B of Fig. 1.

Claim 4

3 .. A process of forming a high molecular weight polylactide polymer capable of being used as a resorbable bone fixation device comprising: polymerizing L(-)lactide monomer in an inert atmosphere in the presence of a catalyst. said catalyst being present in a monomer to catalyst ratio of from 1000 to 300,000, the polymerization being conducted at a temperature of from 105°C to 170°C, the temperature and monomer to catalyst ratio being selected so that the inherent viscosity of the polymer in chloroform is between 4.5 and 10 and satisfies the equation, inherent viscosity = (4.45 + 9.18L - .207T - 1.51L 2 + .032LT) and the unreacted monomer content of the polymer is less than 2% based on the total weight of reaction product and satisfies the equation, unreacted monomer = (28.89 - 15.33L + 6.29L 2 + .0026T 2 -.213LT) wherein L is the log to the base 10 of the monomer to catalyst ratio and T is the temperature in degrees Celsius.

Claim 5

3 .. A process of forming a high molecular weight polylactide polymer capable of being used as a resorbable bone fixation device comprising: polymerizing L(-)lactide monomer in an inert atmosphere in the presence of a catalyst. said catalyst being present in a monomer to catalyst ratio of from 1000 to 300,000, the polymerization being conducted at a temperature of from 105°C to 170°C, the temperature and monomer to catalyst ratio being selected so that the inherent viscosity of the polymer in chloroform is between 4.5 and 10 and satisfies the equation, inherent viscosity = (4.45 + 9.18L - .207T - 1.51L 2 + .032LT) and the unreacted monomer content of the polymer is less than 2% based on the total weight of reaction product and satisfies the equation, unreacted monomer = (28.89 - 15.33L + 6.29L 2 + .0026T 2 -.213LT) wherein L is the log to the base 10 of the monomer to catalyst ratio and T is the temperature in degrees Celsius.

Claim 6

The process of Claim 1 or Claim 3 in which the monomer to catalyst ratio is between 1,100 and 45,000 and the temperature of polymerization is between 105°C and 155°C.

Claim 7

5 . The process of Claim 4 in which the monomer to catalyst ratio is between 1,300 and 20,000 and the temperature of polymerization is-between 110°C and 130°C.

Claim 8

The process of any one of Claims 1 to 5, wherein the catalyst is stanous octoate.

Claim 9

A resorbable bone fixation device capable of maintaining a tensile strength of at least 100 kilograms per square centimeter for 8 weeks after implantation in an animal body made from a poly L(-)lactide polymer having an inherent viscosity in chloroform of from 4.5 to 10 and containing less than 2% of unreacted lactide monomer.

Claim 10

A resorbable bone fixation device capable of maintaining a tensile strength of at least 100 kilograms per square centimeter for 8 weeks after implantation in an animal body made from a poly L(-)lactide polymer having an inherent viscosity in chloroform of from 4.5 to 10 and containing less than 2% of unreacted lactide monomer.

Claim 11

The bone fixation device of Claim 7 in. which the inherent viscosity of the polymer is from 7.0 to 10.0 and which has a tensile strength prior to implantation of at least 500 kilograms per square centimeter.

Claim 12

The bone fixation device of Claim 7 or Claim 8 in which the polymer contains less than 1% unreacted lactide monomer.