BONE FIXING DEVICE

Abstract: A bone fixing device includes a central adjustment link (14); two pin clamp units (12, 16); connection means (50) for attaching clamp units (12, 16) to the central adjustment link (14). Apertures (30) are provided in the two clamp units (12, 16) for removably receiving bone pins to be joined to a patient's bone. The central adjustment link (14) includes an elongated passage (52, 94) provided in an outer housing (32, 92); connection means (50) provided at the outer housing (32, 92) for swivelable connection to a clamp unit (12, 16); a transverse opening (57, 102) in the outer housing (32, 92); an internally threaded adjustment ring nut (36, 104) rotatably mounted in the transverse opening (57, 102); an externally threaded rod (34) threadingly engaging with the ring nut (36, 104); connection means (50) for swivelable connection to a pin clamp unit (12, 16); and a locking pin (58) to engage with the threaded rod (34) inserted into the elongated passage (52, 94) for locking it in position to prevent longitudinal displacement.

Description: TITLE OF INVENTION Bone fixing device. FIELD OF INVENTION The present invention relates to a bone fixing devices. BACKGROUND TO INVENTION Bone fixing devices are used for various orthopaedic purposes, and many different types of such devices are known. The known devices generally are provided with length adjustment means for adjustment of the distance between bone pins carried by clamping units. Such adjustment often is difficult, cumbersome and at times inaccurate. It is an object of the invention to provide a bone fixing device having an adjustment arrangement, which is relatively easy to operate and is accurate. SUMMARY OF INVENTION According to the invention, there is provided a bone fixing device, which includes a central adjustment link; two pin clamp units; connection means for swivelably attaching the two pin clamp units at opposite ends of the central adjustment link; the central adjustment link having adjustment means adapted to allow progressive adjustment for relatively spacing the two pin clamp units; and apertures in the two clamp units for removably receiving bone pins to be joined to a patient's bone, the device being characterized thereby that the central adjustment link includes an outer housing; an elongated passage C ■ ONFIRMATION COPY provided in the outer housing and being open at one end; connection means provided at the outer housing opposite to the open end of the elongated passage for swivelable connection to a clamp unit; a transverse opening in the outer housing extending from its outer surface into the elongated passage; an internally threaded adjustment ring nut rotatably mounted in the transverse opening and having a threaded internal passage; an externally threaded rod received in the elongated passage and threadingly engaging with the ring nut projecting with its one end out of the elongated passage; connection means provided at an end of the threaded rod projecting out of the elongated passage for swivelable connection to a pin clamp unit; at least one locking passage in the outer housing extending transversely from its outer surface into the elongated passage; and a locking pin located movably in the locking passage to engage with the threaded rod inserted into the elongated passage for locking it in position to prevent longitudinal displacement once adjustment by rotation of the nut has been completed. Calibrations may be provided circumferentially on the nut. The threaded rod may have an elongated groove. A guide member may extend through the outer housing into the elongated groove for preventing rotation of the threaded rod relative to the outer housing. Locating means may be provided for keeping the nut in a locked position to prevent rotation thereof. The locating means may include a spring loaded pin mounted in a transverse passage in the outer housing, and a number of circumferentially arranged holes in the nut, the pin being adapted to engage into the holes for preventing rotation of the nut. The connection means may include a ball-and-socket connection. The threaded rod may have a ball for a ball-and-socket connection. The outer housing may have a ball for a ball-and-socket connection. The connection means may be adapted to allow a swivelability through at least 30°. At least one of the clamp units may be constituted by two halve parts and clamping means for clamping the two halve parts to its connection ball, the halve parts having locating recesses for clampingly receiving bone pins for location between the two halve parts. The two halve parts may be semi-circularly shaped in end view. Each halve part may have a semi-circular recess for fitting over a ball of its connection means. At least one of the clamp units may be constituted by a solid cylindrical body, the clamping means may be provided for clamping the cylindrical body to a ball of its connection means, bone pin holes may be provided in the cylindrical body for receiving bone pins, and locking means may be provided for locking the bone pins when located in the bone pin holes as required. BRIEF DESCRIPTION OF DRAWINGS The invention will now be described by way of example with reference to the accompanying schematic drawings. In the drawings there is shown in: Figure 1 a side view of a first embodiment of a bone fixing device with an adjustment arrangement in accordance with the invention; Figure 2 a view of a first embodiment of a split clamp unit for bone pins generally indicated by arrow II in Figure 1 ; Figure 3 an end view of the clamp unit seen along arrow III in Figure 2; Figure 4 a view of the clamp unit seen along arrow IV in Figure 2; Figure 5 a view of the inner rod of the central link of the bone fixing device of Figure 1 ; Figure 6 a sectional end view of the rod seen along arrows VI-VI in Figure 5; Figure 7 a view of the rod seen along arrow VII in Figure 5; Figure 8 an exploded side view of the bone fixing device of Figure 1 but having a solid clamp unit at one end and a split clamp unit (as illustrated in Figures 1 to 3) at the opposite end; Figure 9 on an enlarged scale, a partial sectional view of a housing of a central link of a further adjustment arrangement of a bone fixing device in accordance with the invention; Figure 10 an end view seen along arrow X in Figure 9; Figure 1 1 a detail of the pin and spring assembly of the adjustment arrangement illustrated in Figures 9 and 10; Figure 12 an exploded detail of the various components of the pin and spring assembly shown in Figure 1 1 ; Figure 13 a view of a variation of the bone fixing device of Figure 1 with an end clamp unit at one end; Figure 14 a view of the end clamp unit indicated by reference numeral XIV in Figure 13; Figure 15 a view seen along arrow XV in Figure 14; and Figure 16 a view seen along arrow XVI in Figure 15. DETAILED DESCRIPTION OF DRAWINGS In Figure 1 of the drawings a first embodiment of an orthopaedic or bone fixing device 10 according to the invention is shown. The device 10 includes a first split clamp unit 12, a central link 14 including an elongation adjustment arrangement and a second split pin clamp unit 16. The clamp units 12 and 16 are identical and in the description hereafter reference to the one must be understood also to be reference to the other. Referring also to Figures 2 to 4, the first split clamp unit 12 includes a first semi-cylindrical part 18 and a second semi-cylindrical part 20, which is complementary to the first part 18. The parts 18, 20 together form a solid cylindrical body when clamped together. The parts 18 and 20 have passages 22, 24, which are adapted to receive bolts 22.1, 24.1 (shown in Figure 8) for clamping the parts 18, 20 together. The passages 22 have recesses 26 for receiving the bolt heads of the bolts 22.1 , 24.1. When placed together the parts 18 and 20 define a spherical socket 28 at one end for receiving the ball of the central link 14 as will be described below with reference to Figure 8. A number of holes 30 are provided, these being adapted to receive conventional bone pins or screws for connection to a bone of a patient. These holes 30 are formed spaced apart at intermittent intervals by the two parts 18 and 20 when being placed together. Once the two parts 18 and 20 are fastened together by way of bolts 22.1 , 24.1 , the bone pins or screws and central link 14 are firmly locked in position so as to be immovable. The second clamp unit 16 is similar to the first clamp unit 12 and the description of the first pin clamp unit 12 is applicable hereto. Referring now to Figures 1 , 5, 6 and 7, it is shown that the central link 14 includes an outer housing 32, an inner rod 34 and an internally threaded adjustment nut 36. The inner rod 34 has an external screw thread, which co-operates with the internally threaded nut 36. The nut 36, which is externally knurled, includes circumferentially distributed gripping formations or tommy bar holes 38 for receiving an appropriate tool for assisting to rotate the nut 36 as required for adjustment purposes. The inner rod 34 may be calibrated so that the position of the nut 36 can be accurately determined. As shown in Figure 7 the inner rod 34 has an elongated body 40 with a groove 42 extending longitudinally in the body 40. One side of the body 40 ends in a flat base 44. At the other side first a neck 46 and then a spherical head or ball 48 are formed. The spherically shaped head or ball 48 is received in the socket 28 of the clamp unit 16 to form a ball-and- socket joint for allowing swivelling of the central link 14 in the clamp unit 12 to take place prior to the clamp unit 12 being tightened. The outer housing 32 includes an elongated hole or hollow 52, which is adapted to contain the inner rod 34. As shown in Figure 8 on one side the outer housing 32 ends in a spherical head or ball 54, which is shaped similarly to the spherical head or ball 48 of the inner rod 34 and is received in the socket 28 of the pin clamp unit 12. The other side of the outer housing 32 is shaped as a collar 56 which contains the nut 36 and the inner rod 34. The collar 56 has a transverse passage 57 rotatably receiving the nut 36. The nut 36 is held in place by the inner rod 34 and the collar 56 of the outer housing 32. By turning the nut 36 the inner rod 34 is moved into or out of the outer housing 32. Thereby the overall length of the central link 14 is varied. Once the desired length of the link 14 is obtained, the nut 36 is securely locked in position by tightening means in the form of a pin 58 passing through an internally threaded recessed hole 60 in the collar 56 as shown in Figure 8. A threaded bolt 62 passes through a hole 64 in the collar 56 to be screwed into a wedge 66 which slides in the groove 42 to prevent rotation of the inner rod 34. In use, bone screws or pins are passed through the holes 30 as required and are fixed to bones of a human or animal body to be held together. The screws or pins passing through the clamp units 12 and 16 are applied as deemed necessary to a bone of a patient. Thereafter the nut 36 is operated to pull the clamp unit 12 and the clamp unit 16 relatively together or to separate these until the correct position is reached. Furthermore, for stretching or contraction over a period of time, the nut 36 is turned at specified time intervals as required to effect the necessary longitudinal adjustment of the bone fixing device. The bone fixing device 10 shown in Figure 8 is the same as illustrated in Figure 1 except that in Figure 8 a solid clamp unit 68 is provided at one end and a split clamp unit 12 at the opposite end. The clamp unit 68 has a cylindrical body 70 in which holes 72 for bone pins or screws are provided. Bone pins, when placed in the holes 72, are clamped in position by turning locking screws 72.1 into threaded holes 72.2. The holes 72 can be used as guide holes as in a drill jig for drilling into a patient's bones prior to insertion of the bone pins or screws. Thereby an exact angular and spaced position is obtained in a patient's bone(s) for receiving the bone pins. The body 70 carries a semi-cylindrical protrusion 74 at one end with a semi-spherical recess 76 cooperating with a semi-spherical recess 78 in a loose complementary clamp part 80 to be clamped together by way of two threaded bolts 82 passing through the holes 84 into the holes 86 in the part 74 to be turned onto the internally threaded cap nut 88 to form a spherical recess for receiving the head or ball 48. Referring to Figure 9, a variation of the adjustment arrangement of Figure 1 is shown. The adjustment arrangement 90 includes a housing 92, which replaces the housing 32. The housing 92 has an elongated hole or hollow 94 provided therein, which hollow 94 is open at one end 96. At its opposite end the housing 92 has a ball 98 adapted to be joined to an associated clamp unit 12, 16 or 68 as described above. The housing 92 has a widened or thickened part or collar 100 near the open end 96 in which a transverse aperture 102 is provided in which an internally threaded adjustment ring nut 104 is rotatably fitted. The collar 100 has a passage 106 for receiving a locking arrangement 107 for cooperating with the nut 104. The locking arrangement 107 includes a hollow cylindrical body 108 provided with an external thread 110 along part of its length. Once the locking arrangement 107 is received in the passage 106 the non-threaded part of the body 108 protrudes out of the collar 100. The body 108 has a passage 112 in which a pin 114 is slidably mounted. The pin 114 has a head 116 and, opposite thereto, is screw connected to a control knob 118. The nut 104 has circumferentialy uniformly distributed recesses 120 adapted to receive the head 116 of the pin 114. A spring 122 acts between the body 108 and the head 116 of the pin 114 to bias the head 116 against the nut 104, preferably into the recess 120. In use an inner rod 34 having a threaded end (as shown in Figures 1 and 5) is inserted through the opening 96 into the hollow 94. The threaded end engages with the internal thread of the nut 104. By rotating the nut 104 the rod 34 is moved to or from as indicted by arrow 124. This movement is an adjustment movement and causes lengthening or shortening of the overall bone fixing device 10 as described above. When a suitable adjustment position is reached the pin 114, which has been withdrawn against the action of the spring 122, is released so that the head 116 engages into a relevant recess 120 on the circumference of the nut 104. To adjust the nut 104 again, and thereby shortening or lengthening the bone fixing device 10, the pin 114 is withdrawn against the action of the spring 122 and the nut 104 is rotated as required. A sleeve 126 is provided to rest on the control knob 118 and embracing the body 108 to prevent dirt or other contamination to enter into the space between the control knob 118 and the body 108. Figure 13 shows a variation of the bone fixing device 10 illustrated in Figure 1 , the variation being in the provision of an end clamp unit 128 at one end. This clamp unit 128, of which the individual components are illustrated in Figures 14 to 16, includes a body 130 constituted by two complementary halves 132, 134 which respectively have two holes 136 and a threaded hole 138. Two threaded bolts 140 are screwed through the holes 136 and turned into the holes 138 to clamp the halves 132, 134 together about the head 54 of the link 14. The clamp unit 128 further has a collar 142 onto which an outer disc 144 can be clamped by way of bolts 146. The collar 142 and the disc 144 have complementary semi-circular recesses to define holes 148 for receiving bone pins or screws to be joined to bones of a patient as required. The various components of the bone fixing devices as described with reference to the drawings, except the pins and bolts, are made of light weight high strength aluminium material, suitably anodized if required. List of References 10 bone fixing device 12 split clamp unit 14 central link 16 split clamp unit 18 first semi-cylindrical part 20 second semi-cylindrical part 22 passage 22.1 bolt 24 passage 24.1 bolt 26 recess 28 spherical socket 30 hole 32 outer housing 34 inner rod 36 internally threaded ring nut 38 hole 40 body 42 groove 44 flat base 46 neck 48 ball 50 ball-and-socket joint 52 elongated hole or hollow 54 ball 56 collar 57 transverse passage 58 pin 60 internally threaded recessed hole 62 threaded bolt 64 hole wedge solid clamp unit cylindrical body hole semi-cylindrical protrusion semi-spherical recess semi-spherical recess clamp part threaded bolt hole hole internally threaded cap nut adjustment arrangement housing hole or hollow end of hollow ball collar transverse aperture internally threaded ring nut passage locking arrangement cylindrical body external thread passage pin head control knob recess spring direction of movement sleeve 128 clamp unit 130 body 132 halve of body 134 halve of body 136 hole 138 threaded hole 140 threaded bolt 142 collar 144 outer disc 146 bolt 148 hole

Claims: PATENT CLAIMS 1. A bone fixing device, which includes a central adjustment link (14); two pin clamp units (12, 16); connection means (50) for swivelably attaching the two pin clamp units (12, 16) at opposite ends of the central adjustment link (14); the central adjustment link (14) having adjustment means adapted to allow progressive adjustment for relatively spacing the two pin clamp units (12, 16); and apertures (30) in the two clamp units (12, 16) for removably receiving bone pins to be joined to a patient's bone, characterized thereby that the central adjustment link (14) includes an outer housing (32, 92); an elongated passage (52, 94) provided in the outer housing (32, 92) and being open at one end (44, 96); connection means (50) provided at the outer housing (32, 92) opposite to the open end (44, 96) of the elongated passage (52, 99) for swivelable connection to a clamp unit (12, 16); a transverse opening (57, 102) in the outer housing (32, 92) extending from its outer surface into the elongated passage (52, 94); an internally threaded adjustment ring nut (36, 104) rotatably mounted in the transverse opening (57, 102) and having a threaded internal passage; an externally threaded rod (34) received in the elongated passage (52, 94) and threadingly engaging with the ring nut (36, 104) projecting with its one end out of the elongated passage (52, 94); connection means (50) provided at an end of the threaded rod (34) projecting out of the elongated passage (52, 94) for swivelable connection to a pin clamp unit (12, 16); at least one locking passage (60) in the outer housing (32, 92) extending transversely from its outer surface into the elongated passage (52, 94); and a locking pin (58) located movably in the locking passage (60) to engage with the threaded rod (34) inserted into the elongated passage (52, 94) for locking it in position to prevent longitudinal displacement once adjustment by rotation of the nut (36, 104) has been completed. 2. A device as claimed in claim 1 , characterized thereby that calibrations are provided circumferentially on the nut (36, 104). 3. A device as claimed in claim 1 or claim 2, characterized thereby that the threaded rod (34) has an elongated groove (42). 4. A device as claimed in claim 3, characterized thereby that a guide member (62, 66) extends through the outer housing (32, 92) into the elongated groove (42) for preventing rotation of the threaded rod (34) relative to the outer housing (32, 92). 5. A device as claimed in any one of the preceding claims, characterized thereby that locating means (107) is provided for keeping the nut (104) in a locked position to prevent rotation thereof. 6. A device as claimed in claim 5, characterized thereby that the locating means (107) includes a spring loaded pin (114) mounted in a transverse passage (106) in the outer housing (92), and a number of circumferentially arranged holes (120) in the nut (104), the pin (114) being adapted to engage into the holes (120) for preventing rotation of the nut (104). 7. A device as claimed in any one of the preceding claims, characterized thereby that the connection means (50) includes a ball-and-socket connection. 8. A device as claimed in claim 7, characterized thereby that the threaded rod (34) has a ball (48) for a ball-and-socket connection. . A device as claimed in claim 7, characterized thereby that the outer housing (32, 92) has a ball (54, 98) for a ball-and-socket connection. 10. A device as claimed in any one of claims 7 to 9, characterized thereby that the connection means (50) is adapted to allow a swivelability through at least 30°. 1 1. A device as claimed in any one of the preceding claims, characterized thereby that at least one of the clamp units (12, 16) is constituted by two halve parts (18, 20) and clamping means (82, 22.1 , 24.1 ) for clamping the two halve parts (18, 20) to its connection ball (54), the halve parts (18, 20) having locating recesses (30) for clampingly receiving bone pins for location between the two halve parts (18, 20). 12. A device as claimed in claim 1 1 , characterized thereby that the two halve parts (18, 20) are semi-circularly shaped in end view. 13. A device as claimed in claim 1 1 or claim 12, characterized thereby that each halve part (18, 20) has a semi-circular recess for fitting over a ball (48, 50) of its connection means (50). 14. A device as claimed in any one of the preceding claims, characterized thereby that at least one of the clamp units (68) is constituted by a solid cylindrical body (70), that clamping means (80, 86, 82) is provided for clamping the cylindrical body (70) to a ball (48) of its connection means, that bone pin holes (72) are provided in the cylindrical body (70) for receiving bone pins, and that locking means (72.1 , 72.2) are provided for locking the bone pins when located in the bone pin holes (72) as required.

Inventors: ROETHIG HERMANN FLORIAN, ROETHIG, HERMANN, FLORIAN
Applicants: ROETHIG HERMANN FLORIAN, ROETHIG THOMAS MAX, ROETHIG, HERMANN, FLORIAN, ROETHIG, THOMAS, MAX
Application year: 1999
Main classification: A61B17
IPC codes: A61B17