the present invention is directed to a system for the fixation of fractured or otherwise damaged bones via one or both of a variable angle insertion and a fixed angle insertion of a bone screw through a bone plate hole . specifically , a bone plate according to the present invention is provided with a central through hole configured to receive a first bone screw therethrough at any user selected angle relative to a longitudinal axis of the through hole within a permitted range of angulation . a plurality of second bone screws may also be inserted through outlying portions of the bone plate hole , each defining a separate plate hole axis . the outlying portions of the bone plate hole are formed as substantially circular peripheral holes configured to overlap and be open to the through hole to form a composite hole having any of a plurality of shapes depending on the placement and number of the peripheral holes relative to the through hole , as will be discussed in greater detail with respect to particular embodiments . the peripheral holes may be configured with holes axes selected so that the second bone screws may only be inserted therethrough at predetermined angles relative to a surface of the bone plate . it is noted that although the peripheral holes and through holes are depicted with predetermined angles in the system of the present invention , these bone plate holes may extend through the bone plate at any angle without deviating from the spirit and scope of the present invention and may be selected to conform to the requirement of a particular procedure . fig1 to 8 illustrate a first exemplary embodiment of the invention comprising a bone plate 1 including one through hole 9 and three partially cylindrical peripheral holes 2 arranged peripherally around the through hole 9 in such a way that they overlap with the through hole 9 and are open thereto , as will be described in greater detail below . it is noted that although the through hole 9 is depicted with a triangular cross - sectional shape , any other cross - sectional shape may be employed without deviating from the spirit and scope of the present invention . the bone plate 1 comprises a proximal surface 7 and a bone - oriented distal surface 8 . the through hole 9 has a longitudinal axis 6 connecting the proximal and distal surfaces 7 , 8 , the longitudinal axis 6 extending orthogonally to the proximal surface 7 . the through hole 9 is at least partially bordered by a wall 10 including three convex sections 15 provided with projections such as a thread 5 or thread - like structures for receiving a central bone screw 30 under a variable angle . as will be described in greater detail later , each of the three convex sections 15 of fig1 is curved with a predetermined radius of curvature . in an alternate embodiment ( not shown ), any number and combination of the convex sections 15 may be formed with a first radius of curvature while the remainder of the convex sections 15 may be formed with a second radius of curvature . each of the peripheral holes 2 each has a hole axis 11 extending between the proximal and distal surfaces 7 , 8 and are provided with a thread 4 for receiving peripheral bone screws 20 , as shown in fig6 - 8 . the peripheral holes 2 are arranged peripherally around the through hole 9 at equal angles relative to each other . in the embodiment shown where three peripheral holes 2 are employed , the axes 11 of the peripheral holes 2 , when viewed in a cross - section orthogonal to the longitudinal axis 6 of the through hole 9 , define an equilateral triangle . furthermore , the three peripheral holes 2 overlap the through hole 9 in such a way that the peripheral holes 2 and through hole 9 form a composite hole structure suitable to receive 3 peripheral bone screws 20 , as shown in fig5 to 8 and / or one central bone screw 30 , as shown in fig2 to 4 . as shown in fig5 , the peripheral holes 2 each also comprise a thread 4 , which , in one embodiment of the present invention , may be a multiple thread . when viewed in a cross - section orthogonal to the longitudinal axis 6 of the through hole 9 , each of the convex sections 15 is centrally positioned along a respective corner of an equilateral triangle . each convex section 15 is convexly curved in a direction from the proximal surface 7 to the distal surface 9 so that an apex of each of the convex sections 15 is located radially outside the through hole 9 . a bone screw 30 can be inserted into the through hole 9 under a surgeon selected angle so that a screw axis 33 of the bone screw 30 is offset by an angle α relative to the longitudinal axis 6 of the through hole 9 . the through hole 9 of the present invention may be con figured so that the bone screw 30 insertable therethrough is smaller , larger or the same size as the bone screws 20 insertable through the peripheral holes 2 . the composite hole structure therefore includes three radially symmetrically arranged convex sections 15 centrally located on the sides of an equilateral triangle and three peripheral holes 2 in the corners of the equilateral triangle . the axes 11 of the peripheral holes 2 are arranged at a distance from the longitudinal axis 6 which is dimensioned in such a way that the peripheral holes 2 overlap the through hole 9 and extend over an angle of more than 180 ° between their transitions to the through hole 9 . the wall 10 of the through hole 9 comprises n = 3 wall portions with each wall portion being limited by a transition to the periphery of a first peripheral hole 2 at one of its ends and by a transition to the periphery of a second peripheral hole 2 at its other end . in the present embodiment each convex section 15 does not extend over the whole length of the wall portion limited by the transitions . the thread 5 or thread - like structure extends over the whole length of the three convex sections 15 with a constant depth of thread . the depth of thread of the thread 5 or thread - like structure decreases between each end of the convex section 15 and each of the two transitions to one of the peripheral holes 2 . as illustrated in fig2 to 4 the through hole 9 tapers radially inward toward the distal surface 8 of the bone plate 1 . a central bone screw 30 with a screw axis 33 and a screw head 31 is inserted in the through hole 9 . the screw head 31 is spherically shaped and comprises an external thread 32 so that the central bone screw 30 can be inserted into the through hole at a user - selected angle α between the screw axis 33 and the longitudinal axis 6 of the through hole 9 . instead of a central bone screw 30 comprising a spherically shaped screw head 31 with an external thread 32 a central bone screw comprising a conically shaped screw head with an external thread could be inserted into the through hole 9 . in the latter case the central bone screw would be inserted into the through hole 9 at a fixed angle ( e . g ., with the screw axis and the longitudinal axis 6 of the through hole 9 coinciding ). as shown in fig7 and 8 , the peripheral holes 2 are configured so that each of the hole axes 11 is angled at approximately 20 ° relative to the longitudinal axis 6 of the through hole 9 . in another embodiment of the present invention , the peripheral holes 2 may be angled at any other angle relative to the longitudinal axis 6 and may optionally also each extend along different angles , as those skilled in the art will understand . as illustrated in fig7 each of the peripheral holes 2 tapers radially inward towards the distal surface 8 of the bone plate 1 . a peripheral bone screw 20 with a screw axis 23 and a screw head 21 is inserted into each of the peripheral holes 2 . the screw head 21 is conically shaped and comprises an external thread 22 so each peripheral bone screw 20 can be inserted into one of the peripheral holes 2 at a fixed angle with the screw axis 23 and the hole axis 11 of the peripheral hole 2 coinciding . instead of peripheral bone screws 20 comprising conically shaped screw heads 21 with an external thread 22 , peripheral bone screws comprising spherically shaped screw heads with an external thread may be inserted into the peripheral holes 2 . in the latter case the peripheral bone screws may be inserted at a user selected variable angle between the screw axis 23 and the hole axis 11 of the peripheral hole 2 . in fig9 to 11 another embodiment is illustrated which differs from the embodiment of fig1 to 8 only in that the generally polygonal through hole 9 comprises rounded corners instead of the n = 3 peripheral holes 2 arranged in the corners . similarly to the embodiment of fig1 to 8 , the wall 10 of the through hole 9 comprises n = 3 convex sections 15 which in a cross - section orthogonal to the longitudinal axis 6 are centrally located on the sides of an equilateral triangle . each of the convex sections 15 is convexly curved in a cross - section orthogonal to the longitudinal axis 6 of the through hole 9 with the apex of each convex section 15 located on a middle line orthogonal to one side of the equilateral triangle . due to the convex sections 15 , a bone screw 30 may be inserted into the through hole 9 under a surgeon selected angle relative to the axis 6 . the through hole 9 includes three radially symmetrically arranged convex sections 15 centrally located on the sides of an equilateral triangle and three concavely rounded sections in the corners of the equilateral triangle . the wall 10 of the through hole 9 therefore comprises n = 3 wall portions whereof each wall portion extends along one side of an equilateral triangle and is limited by a transition to a first concavely rounded section at one of its ends and by a transition to a second concavely rounded section at its other end . in the present embodiment each convex section 15 extends over the whole length of the wall portion limited by the transitions . the thread 5 or thread - like structure extends over the whole periphery of the through hole 9 . the depth of thread of the thread 5 or thread - like structure can decrease in the concavely rounded sections . as illustrated in fig1 the through hole 9 tapers towards the distal surface 8 of the bone plate 1 . a central bone screw 30 with a screw axis 33 and a screw head 31 is inserted in the through hole 9 . the screw head 31 is spherically shaped and comprises an external thread 32 so that the central bone screw 30 can be inserted into the through hole at a user - selected variable angle α between the screw axis 33 and the longitudinal axis 6 of the through hole 9 . in fig1 to 14 another embodiment of the bone plate 1 is illustrated which comprises two through holes 9 . similarly to the embodiment of fig9 to 11 , the through hole 9 has cross - sectional area orthogonal to the longitudinal axis 6 with a center 14 located on the longitudinal axis 6 with each of the n = 3 convex sections 15 being limited by two radii intersecting each other in the center 14 and enclosing an angle ω which is smaller than 120 °. the wall 10 of each of the two through holes 9 comprises n = 3 wall portions with each wall portion extending along one side of an equilateral triangle and limited by a transition to a first concavely rounded section at one of its ends and by a transition to a second concavely rounded section at its other end . similarly to the embodiment of fig9 to 11 , each convex section 15 extends over the whole length of the wall portion limited by the transitions . the through holes 9 differ from the through hole 9 of the embodiment of fig9 to 11 only in that the thread 5 or thread - like structure does not extend over the whole periphery of the through hole 9 . the depth of thread of the thread 5 or thread - like structure decreases on each end of the convex section 15 at the transition between the convex section 15 and the concavely rounded section in such a way that a portion of the concavely rounded sections is unthreaded . as illustrated in fig1 the through hole 9 tapers radially inward toward the distal surface 8 of the bone plate 1 . similarly to the embodiment of fig9 to 11 , a central bone screw 30 with a screw axis 33 and a screw head 31 can be inserted in the through hole 9 . by using a central bone screw 30 the screw head 31 of which is spherically shaped with an external thread 32 , the central bone screw 30 may be inserted into the through hole 9 at a user - selected , variable angle α of the screw axis 33 to the longitudinal axis 6 of the through hole 9 . fig1 illustrates a further embodiment of the through hole 9 which differs from the embodiment of fig1 to 14 only in that it comprises n = 4 convex sections 15 . each of the n = 4 convex sections 15 is limited by two radii intersecting each other in the center 14 and enclosing an angle ω which smaller than 90 °. the wall 10 of each of the two through holes 9 comprises n = 4 wall portions with each wall portion extending along one side of a square and limited by a transition to a first concavely rounded section at one of its ends and by a transition to a second concavely rounded section at its other end . similarly to the embodiment of fig9 to 11 , each convex section 15 extends over the whole length of the wall portion limited by the transitions . the thread 5 or thread - like structure does not extend over the whole periphery of the through hole 9 . the depth of thread of the thread 5 or thread - like structure decreases on each end of the convex section 15 at the transition between the convex section 15 and the concavely rounded section in such a way that a portion of the concavely rounded sections is unthreaded . fig1 illustrates again a further embodiment of the through hole 9 which differs from the embodiment of fig1 only in that the wall 10 of the through hole 9 comprises n = 4 straight sections 15 and that the depth of thread of the thread 5 or thread - like structure decreases from a middle line orthogonal to one side of the square towards the transition between the straight section 15 and each of the concavely rounded sections in such a way that the concavely rounded sections are unthreaded . fig1 and 18 illustrate again a further embodiment of the through hole 9 which differs from the embodiment of fig1 only in that the n = 3 peripheral holes 2 are configured to receive conventional cortex screws . each peripheral hole 2 comprises a spherical recess 25 penetrating partially into the bone plate 1 from the proximal surface 7 and axially adjacent to a conically enlarging lower section 26 extending between the spherical recess 25 and the distal surface 8 of the bone plate 1 . due to the spherical recess 25 , a conventional cortex screw with a spherical head may be inserted into each of the peripheral holes 2 at a user - selected angle with respect to the axis 11 of the peripheral hole 2 . the n = 3 straight or convex sections 15 of the wall 10 of the through hole 9 are configured similarly to the embodiment of fig1 . although the invention and its advantages have been described in detail , it should be understood that various changes , substitutions , and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims . moreover , the scope of the present application is not intended to be limited to the particular embodiments of the process , machine , manufacture , composition of matter , means , methods and steps described in the specification . as one of ordinary skill in the art will readily appreciate from the disclosure of the present invention , processes , machines , manufacture , composition of matter , means , methods , or steps , presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention . it will be appreciated by those skilled in the art that various modifications and alterations of the invention can be made without departing from the broad scope of the appended claims . some of these have been discussed above and others will be apparent to those skilled in the art .
a bone plate includes a first through hole extending through the plate along a first longitudinal axis from a proximal surface of the plate to a bone - facing distal surface thereof which , when the plate is placed on a target portion of bone in a desired orientation , faces the bone . an outer wall of the first through hole includes three wall sections provided with projections for receiving a screw head of a bone screw . the three wall sections are straight or convex .