Device and method for cementing a hip prosthesis in a femoral canal

Claim 3

A device as in claim 1 wherein said cementing means comprises: (a) means for applying said cement to said prepared femoral canal under pressure, and (b) means for maintaining said pressure until said cement hardens about said prosthesis stem.

Claim 4

A device as in claim 1 wherein said mounting means comprises: (a) a base guide adapted to be rigidly attached to the proximal end of said femur as a guide for removing the neck of said femur to expose the femoral calcar and canal, and (b) a lid clamp for rigidly securing the femoral stem to said base guide.

Claim 5

A device as in claim 3 wherein said base guide comprises: (a) a generally U-shaped attachment with the open end of said U being wider than the closed end, (b) a wing extending upwardly and outwardly from the outer end of each arm of said U, and (c) at least one pair of orifices on said U-shaped attachment in spaced relationship for allowing a pin to be inserted through the cortex of said femur when said pin is inserted from one orifice to the other, thereby rigidly fastening said attachment to said femur.

Claim 6

A device as in claim 4 wherein said closed end of said U-shaped attachment is adapted to be held snugly against or near the lesser trochanter of said femur.

Claim 7

A device as in claim 5 wherein said closed end of said U-shaped attachment is notched for the lesser trochanter to allow a snug fit.

Claim 8

A device as in claim 6 further including means on said base guide for rigidly securing said lid clamp to said base guide.

Claim 9

A device as in claim 3 wherein said means for applying said cement to said femoral canal comprises: (a) a separator-sealer device having first and second orifices therein for operable contact with said femoral canal and mounted about the neck and collar junction of said prosthesis for providing a seal around the collar of said prosthesis and over the calcar of said femur, (b) a ceiling mounted above said separator-sealer and rigidly attached to said base guide, said ceiling having first and second orifices super-imposed over the abutting corresponding ones of said first and second orifices of said separator-sealer, said first orifice providing a means for inserting cement under pressure into said femoral canal, around said prosthesis collar and over said femoral calcar and said second orifice providing an air vent to allow air displaced by said cement to leave said canal, (c) said lid clamp enclosing said femoral prosthesis head, and (d) means on said ceiling for enabling said lid clamp to be rigidly attached thereto whereby said femoral stem prosthesis is held rigidly in place while said cement is applied to and hardens in said femoral canal, around said prosthesis collar and over said femoral calcar.

Claim 10

A device as in claim 8 wherein said separator-sealer is smaller than and fits within said base guide.

Claim 11

A device as in claim 9 wherein said separator-sealer comprises: (a) a plastic body having a concave inferior surface whereby it rests on said femur only on the outer edges of said plastic whereby said cement can cover the femoral calcar and surround the collar of said femoral stem prosthesis, and (b) an absorbable component applied to said inferior surface to prevent said separator-sealer from being cemented to said femur.

Claim 12

A device as in claim 10 wherein said plastic is semi-rigid when cured or hardened, has a low melting point, and does not cure or harden rapidly.

Claim 13

A device as in claim 9 wherein said base guide includes a groove around the upper edge of the U-shaped portion thereof.

Claim 14

A device as in claim 12 wherein: (a) said ceiling is larger than said U-shaped portion of said base guide, and (b) a flange extends downwardly about the periphery of the underside of said ceiling, said flange being superimposed over the coextensive with said groove in said base guide whereby said groove and flange form a seal to prevent said cement from escaping.

Claim 15

A device as in claim 13 wherein said cement is methyl methacrylate.

Claim 16

A device as in claim 14 wherein said separator-sealer, said ceiling and said lid clamp are formed from opposed complimentary sections thereby allowing them to be placed around said stem prosthesis from each side thereof.

Claim 17

A device as in claim 8 further including: (a) an ajustment unit for varying the position of said prosthetic stem in said canal, said adjustment unit comprising: (i) a pliable material cylindrical in shape, (ii) an orifice eccentrically located along a longitudinal axis of said material thus creating a thick side and a thin side, and (iii) a slit extending through and along said thin side whereby said material may be positioned about the neck of said prosthesis and rotated to a desired location thereby forcing said prosthesis to a fixed position when said lid clamp is attached thereto.

Claim 18

A device as in claim 16 wherein said adjustment unit is formed in two complimentary sections for ease of mounting about the neck of said prosthesis.

Claim 21

A method as in claim 18 wherein the step of attaching said prosthesis to said femur in a rigid relationship further comprises the steps of: (a) fastening a base guide to the proximal end of said femur in a fixed relationship, (b) resecting the neck of said femur along a line defined by said base guide to expose the femoral calcar and canal, (c) cleaning said femoral canal, (d) inserting said prosthesis stem in said canal in a desired position, and (e) rigidly securing said prosthesis to said base guide.

Claim 22

A method as in claim 19 further comprising the steps of: (a) X-raying said inserted prosthesis to determine the correct position thereof, (b) repeating steps (d) and (e) until the X-ray reveals said prosthesis to be in the correct position in said canal, and (c) applying cement to said femoral canal under pressure.

Claim 23

A method as in claim 20 wherein the step of rigidly securing said prosthesis to said base guide comprises the steps of: (a) enclosing said prosthesis head with a lid clamp, and (b) rigidly attaching said lid clamp to said base guide to hold said prosthesis in a rigid position.

Claim 24

A method as in claim 21 further including the steps of: (a) forming an adjustment unit from a cylindrical shaped, pliable material, (b) locating an orifice eccentrically along a longitudinal axis of said cylindrical shaped material thereby creating a thin side and a thick side, and (c) forming a slit extending through and along the length of the thin side of said material whereby said material may be positioned as desired about the neck of said prosthesis and between the neck and lid clamp whereby the prosthesis is positioned as desired in said canal.

Claim 25

A method as in claim 22 wherein the step of applying said cement to said femoral canal under pressure further comprises the steps of: (a) mounting a separator-sealer about the prosthesis neck and collar junction, said sealer having first and second orifices in operative contact with said femoral canal, (b) mounting a ceiling above said separator-sealer, said ceiling having first and second orifices super-imposed over and abutting corresponding ones of said first and second orifices of said separator-sealer, and a third orifice through which the neck of said prosthesis passes, (c) rigidly securing said ceiling to said base guide, (d) rigidly securing said lid clamp to said ceiling whereby said prosthesis is fixedly located with respect to said femoral canal, (e) applying cement to said first orifice of said ceiling under pressure whereby said cement enters said femoral canal about said prosthesis stem, around said prosthesis collar, and over said femoral calcar, said cement being applied under pressure until the cement begins to flow from said second orifice, and (f) closing said second orifice and maintaining said pressure until said cement hardens in said femoral canal about said prosthesis stem.

Claim 26

A method as in claim 23 further comprising the steps of: (a) forming said separator-sealer of plastic, (b) adding an absorbable component on the underside thereof, and (c) shaping said plastic with a concave underside whereby it rests on said femur only on the outer edges of said plastic whereby said cement can cover the femoral calcar and surround the collar of said femoral stem prosthesis.

Claim 27

A method as in claim 24 further comprising the step of utilizing methyl methacrylate as said cement.

Claim 28

A method as in claim 25 further comprising the step of forming said separator-sealer, said ceiling and said lid clamp with opposed complimentary sections which may be placed about said stem prosthesis from opposite sides thereof.

Claim 29

A method as in claim 24 further including the step of sealing any space between said base guide and said femur with a malleable material to prevent said cement from adhering to said base guide and the outside of said femur.

Claim 32

A device as in claim 28 wherein said mounting means comprises: (a) a lid clamp guide attached to said collarless femoral stem hip prosthesis while said prosthesis is correctly positioned in said femoral canal, (b) a base guide rigidly attached to said lid clamp guide whereby said base guide may be correctly positioned, and (c) means for fixedly attaching said base guide in its correct position to the proximal end of said femur whereby said lid clamp guide may be removed and the remaining head and neck of said femur is resected using said base guide as a reference.

Claim 33

A device as in claim 29 wherein said lid clamp guide comprises: (a) a ceiling portion for correctly positioning said base guide, (b) a clamp integrally formed with said ceiling portion for snugly fitting about the head and a portion of the neck of said prosthesis, and (c) opposed complimentary sections forming said ceiling portions and clamp thereby allowing said lid clamp guide to be placed around said stem prosthesis head and neck from opposite sides.

Claim 34

A device as in claim 30 wherein said means for fixedly attaching said base guide to said proximal end of said femur in its correct position comprises: (a) a base guide having a U-shaped frame, (b) at least one orifice in each leg of said U-shaped frame, (c) a pin threaded on each end and inserted from one orifice in one of said legs and adapted to pass through said femur and the other orifice in said other leg, and (d) nuts tightened on said threads on each end of said pin whereby said base guide is adapted to be attached to said femur in a rigid relationship.

Claim 35

A device as in claim 31 further including: (a) a plurality of orifices in each of said legs of said U-shaped frame, and (b) a like plurality of threaded pins whereby each pin may pass from one orifice in one leg through said femur and a corresponding orifice in said other leg to hold said base guide in said rigid relationship to said femur.

Claim 38

A method as in claim 33 further including the steps of: (a) providing an orifice in said ceiling-lid clamp, and (b) introducing said cement into said femoral canal and under said ceiling-lid clamp through said orifice under pressure.