Bioabsorbable interference bone fixation screw

Claim 2

An interference bone fixation screw as recited in claim 1 wherein said lobe openings (36) have outer ends (42) disposed a first radial distance from said longitudinal axis and inner ends (46) disposed a second radial distance from said longitudinal axis less than said first radial distance, said lobe openings (36) tapering inwardly from said outer ends to said inner ends to define planar force receiving walls (40) between said outer ends and said inner ends for receiving concentric rotational forces from the driver applied perpendicular to said walls (40).

Claim 3

An interference bone fixation screw as recited in claim 2 wherein said drive recess means (30) includes a cylindrical cavity (34) disposed concentrically in said proximal end (14) of said body (12) and said inner ends of said lobe openings (36) communicate with said cylindrical cavity (34).

Claim 4

An interference bone fixation screw as recited in claim 3 wherein said cylindrical cavity (34) is defined by a plurality of inner arcuate walls (38) positioned, respectively, between said inner ends of said lobe openings (36).

Claim 5

An interference bone fixation screw as recited in claim 4 wherein said outer ends of said lobe openings are defined by outer arcuate walls (42) joining said force receiving walls (40).

Claim 6

An interference bone fixation screw as recited in claim 5 wherein said outer arcuate walls (42) define arcs of a circle, said inner arcuate walls (38) define arcs of a circle and said arcs defined by said inner arcuate walls are longer than said arcs defined by said outer arcuate walls.

Claim 7

An interference bone fixation screw as recited in claim 6 wherein said thread means (18) defines a major diameter and said body (12) defines a minor diameter extending longitudinally from said proximal end toward said distal end.

Claim 8

An interference bone fixation screw as recited in claim 7 wherein the diameter of said circle defined by said outer arcuate walls (42) is about 78 % said minor diameter.

Claim 9

An interference bone fixation screw as recited in claim 7 or 8 wherein the diameter of said circle defined by said inner arcuate walls (38) is about 47% said minor diameter.

Claim 10

An interference bone fixation screw as recited in any one of claims 6-9 wherein said arcs defined by said outer arcuate walls (42) subtend about 50°.

Claim 11

An interference bond fixation screw as recited in any one of claims 3-10 further including a longitudinal guide bore (50) disposed concentrically in said body (12) to extend longitudinally from said cavity (34) to said distal end (16).

Claim 12

An interference bone fixation screw as recited in claim 11 further including an end wall (32) disposed in said body perpendicular to said longitudinal axis, said drive recess means (30) extending longitudinally in said body (12) from said proximal end (14) to said end wall (32).

Claim 13

An interference bone fixation screw as recited in any preceding claim wherein said thread means (18) includes a helical screw thread (20).

Claim 14

An interference bone fixation screw as recited in claim 13 wherein said helical screw thread (20) defines a major diameter and said body (12) defines a minor diameter along said helical screw thread.

Claim 15

An interference bone fixation screw as recited in claim 14 wherein said minor diameter is 55% to 75% said major diameter.

Claim 16

An interference bone fixation screw as recited in claim 13, 14 or 15 wherein said helical screw thread (20) is of uniform pitch.

Claim 17

An interference bone fixation screw as recited in claim 13, 14, 15 or 16 wherein said thread means (18) further includes a spiral screw thread (24) extending longitudinally from said helical screw thread (20) to said distal end (16).

Claim 18

An interference bone fixation screw as recited in claim 17 wherein said spiral screw thread (24) has a pitch and said spiral screw thread pitch is greater than said helical screw thread pitch.

Claim 19

An interference bone fixation screw as recited in any preceding claim wherein said body is cylindrical.

Claim 20

An interference bone fixation screw as recited in any preceding claim wherein said thread means is disposed on said body from said proximal end to said distal end.

Claim 21

An interference bone fixation screw as recited in any preceding claim wherein said interference bone fixation screw is made entirely of Poly (L-Lactide).

Claim 22

An interference bone fixation screw as recited in any preceding claim wherein there are three of said lobe openings (36).

Claim 23

An interference bone fixation screw as recited in any preceding claim wherein the cross-section of said drive recess means (30) is constant through a substantial portion of the longitudinal length of said drive recess means.

Claim 24

An interference bone fixation screw as recited in any preceding claim wherein the longitudinal length of said drive recess means (30) is 48% to 95% the length of said body (12) from said proximal end (14) to said distal end (16).

Claim 25

An interference bone fixation screw (10) in combination with a driver (60) for rotating the screw comprising a cylindrical body (12) having a proximal end (14), a distal end (16) and a longitudinal axis; thread means (18) disposed on said body (12) for engaging bone; drive recess means (30) in said proximal end (14) of said body for matingly receiving said driver (60); said interference bone fixation screw (10) being fabricated entirely of bioabsorbable material; and a driver (60) including shaft means (62) for being received in said drive recess means (30); characterised in that said drive recess means includes a cylindrical cavity (34) disposed concentrically in said body (12) and a plurality of lobe openings (36) disposed around said cavity (34) in communication therewith, each of said lobe openings (36) being defined by force receiving walls (40) extending radially outwardly from said cavity (34), said force receiving walls (40) extending longitudinally within said body (12) along a substantial portion of its length; and in that said driver includes a plurality of lobe means (72) having force transmitting walls (74) extending radially outwardly from said shaft means (62) for applying forces to said force receiving walls (40) when said driver (60) is rotated.

Claim 26

An interference bone fixation screw and driver as recited in claim 25 including an end wall (32) disposed in said body (12) perpendicular to said longitudinal axis, said drive recess means (30) extending longitudinally from said proximal end (14) to said end wall (32).

Claim 27

An interference bone fixation screw and driver as recited in claim 26 wherein said shaft means (62) includes an end surface (70) disposed perpendicular to the longitudinal axis of said shaft means for engaging said end wall (32).