Surgical stapler with corrugated thermoplastic leaf spring

1. A surgical stapler comprising:

a housing having side walls an end wall, a front wall, and a upper side that define a channel;

a trigger;

a thermoplastic leaf spring having a proximal end and a distal end, the leaf spring comprising a non-corrugated portion and a corrugated portion, wherein the proximal end is located closer to a staple release area than the distal end;

wherein the leaf spring is attached to the trigger at the proximal end;

wherein the leaf spring extends from the trigger, through the channel toward the upper side; and

wherein at least one of

(i) a corrugation amplitude in the corrugated portion is dissipating amplitude or accumulating amplitude, from the proximal end to the distal end;

(ii) the thermoplastic leaf spring exhibits maximum Von Mises stress of no more than 51 MPa for a load of 85% of a stapler load; and

(iii) the corrugated portion has a corrugation amplitude h of 1.0 to 10 mm, an amplification constant k of 0.2 to 2.0, a corrugation angle φ of 75 to 15 degrees, and a number of corrugations of 2 to 24.

2. The surgical stapler of claim 1 , wherein the corrugated portion has a thickness that is different than the non-corrugated portion.

3. The surgical stapler of claim 1 , wherein a thickness ratio between the proximal end and the distal end is 20:19 to 2:1.

4. The surgical stapler of claim 1 , wherein the thermoplastic material is polybutylene terephthalate; acrylonitrile-butadiene-styrene; polycarbonate; acrylic-styrene-acrylonitrile; acrylonitrile-(ethylene-polypropylene diamine modified)-styrene; phenylene ether resins; polyamides; phenylene sulfide resins; polyvinyl chloride; high impact polystyrene; thermoplastic polyolefins; or a combination comprising at least one of the foregoing.

5. The surgical stapler of claim 1 , wherein the thermoplastic leaf spring has Poisson Ratio of 0.3 to 0.5.

6. The surgical stapler of claim 1 , wherein Young's modulus of the thermoplastic leaf spring is 0.1 to 70 GPa.

7. The surgical stapler of claim 1 , wherein a thickness at the proximal end and the distal end of the thermoplastic leaf spring is 0.5 and 10 mm.

8. The surgical stapler of claim 1 , wherein the thermoplastic leaf spring has a span (L) of 50 to 150 mm and a width (W) of 2 to 20 mm.

9. The surgical stapler of claim 1 , wherein the corrugated portion has a length (l) of 2 to 50 mm.

10. The surgical stapler of claim 1 , wherein the corrugation amplitude is dissipating amplitude or accumulating amplitude, from the proximal end to the distal end.

11. The surgical stapler of claim 1 , wherein the thermoplastic leaf spring exhibits maximum Von Mises stress of no more than 51 MPa for a load of 85% of a stapler load.

12. The surgical stapler of claim 11 , wherein the surgical stapler has fixed thickness form proximal end to distal end of 1.5 to 2.5 and exhibits maximum Von Mises stress of no more than 42 MPa for a load of less than or equal to 60%.

13. The surgical stapler of claim 1 , wherein the thermoplastic leaf spring has a 10% decrease in thickness from the proximal end to the distal end.

14. The surgical stapler of claim 1 , wherein the corrugation amplitude h is 1.0 to 10 mm, an amplification constant k is 0.2 to 2.0, a corrugation angle φ is 75 to 15 degrees, and a number of corrugations is 2 to 24.

15. The surgical stapler of claim 1 , wherein the thermoplastic leaf spring is configured to undergo 40 to 60 compression-release cycles without increase in maximum Von Mises stress for a load of 85% of a stapler load.

16. The surgical stapler of claim 1 , wherein the thermoplastic leaf spring is configured to undergo no less than 38 compression-release cycles without increase in maximum Von Mises stress for a load of 85% of a stapler load.

17. A surgical stapler comprising:

a housing having side walls an end wall, a front wall, and a upper side that define a channel;

a trigger;

a thermoplastic leaf spring having a proximal end and a distal end, the leaf spring comprising a non-corrugated portion and a corrugated portion, wherein the proximal end is located closer to a staple release area than the distal end;

wherein the leaf spring is attached to the trigger at the proximal end;

wherein the leaf spring extends from the trigger, through the channel toward the upper side;

wherein the corrugated portion begins at a distance (X 0 ) of 50% to 95% from the distal end based on a span (L) of the surgical stapler.

18. Method for using a surgical stapler, comprising:

creating relative motion between a housing and a trigger of a surgical stapler by placing a load on the surgical stapler;

contacting a surface of the trigger with a cartridge comprising staple pins;

releasing a staple pin from the cartridge and folding ends of the staple pin;

releasing the load; and

biasing the housing and trigger apart with a thermoplastic leaf spring having a proximal end and a distal end, the leaf spring comprising a non-corrugated portion and a corrugated portion, wherein the leaf spring is attached to the trigger at the proximal end, and wherein the leaf spring extends from the trigger, through a channel in the housing, and

wherein at least one of

(i) a corrugation amplitude in the corrugated portion is dissipating amplitude or accumulating amplitude, from the proximal end to the distal end;

(ii) the thermoplastic leaf spring exhibits maximum Von Mises stress of no more than 51 MPa for a load of 85% of a stapler load; and

(iii) the corrugated portion has a corrugation amplitude h of 1.0 to 10 mm, an amplification constant k of 0.2 to 2.0, a corrugation angle φ of 75 to 15 degrees, and a number of corrugations of 2 to 24.