Vertebral locking and retrieving device

Abstract: A vertebral locking and retrieving system comprises at least one lock pin (10), a coupling component (20), a remedial component, and a plurality of locking components (50-56). The lock pin is composed of a threaded end portion (11) and a receiving mount (12), which form therebetween a specified angle. The coupling component is connected at one end thereof to the receiving mount of the lock pin. The remedial component is secured at one end thereof to the deformed vertebra or to the upper vertebra or the lower vertebra immediately adjacent to the deformed vertebra and is connected at another end thereof to another end of the coupling component. The locking components are provided to fixedly fasten the lock pin and the remedial component with the coupling component.

Description: The invention relates to a vertebral locking and retrieving device. EP-A-0 392 927 discloses a vertebral locking device comprising a locking pin with a threaded portion at one end for being secured to a vertebra. The threaded portion is inserted in the vertebra after the vertebra has been moved to its normal position in order to fix it in this position. The threaded portion defines a longitudinal axis and has a receiving mount at an end thereof. The receiving mount is formed at a specific angle in order to adapt the device to the specific curvature of the spine. A coupling means, comprising a rod, for interconnecting said locking pin with a remedial component of the same type is inserted in a through hole of the receiving mount and secured thereof by means of additional screws. In practice, the position of the respective vertebra has to be corrected before applying the vertebral locking device thereto. US-A-4 611 580 discloses another vertebral locking device comprising straight locking pins which are secured to the respective vertebra by a threaded portion. A threaded rod serves as a coupling means for interconnecting two locking pins. The threaded rod extends through a hole in each of the locking pins and is fixed thereto by two nuts sandwiching the receiving mount with the hole therebetween. This vertebral locking device is implanted after the position of the vertebras has been corrected. It is the object of the invention to provide a vertebral locking and retrieving device which may be applied to different specific curvatures of various vertebra and having means for using the device to help the surgeon correcting the position of the vertebra to its normal position by keeping the problems during and after the surgical operation low. According to the invention, this object is attained with a vertebral locking and retrieving device having the features cited in claim 1. Advantageously, the vertebral locking and retrieving device according to the invention enables a surgeon to restore a vertebra to its desired position of curvature relative to other normal, healthy vertebras as a result of the tightening of the nuts. This is possible because the locking pin comprises said angle permitting the locking pin to negotiate and co-operate with the vertebra. Hence, the whole system may be adapted to the respective curvature of the spinal column and the tightening operation of the nuts restores the slipped vertebra. By screwing the nuts, the slipped vertebra may be retrieved to its normal position. The present invention serves to simplify the surgical operation in such ways that it does not require of a surgeon to make a large incision, thereby minimising the risk of excessive bleeding by the patient receiving treatment; the patient's ability to move about is not seriously comprimised by the surgical operation; and the patient's nervous system is less vulnerable to the pressure exerted thereon by the implanted system. Advantageous features and embodiments of the invention are cited in the dependent claims. The receiving mount of the lock pin in the preferred embodiments of the present invention take the form of a fork, preferably a horseshoe-type structure, or a ring-type structure. Additional threaded holes, preferably two threaded holes, may be provided on both arms of the receiving fork so as to reinforce the connection between the lock pin and the coupling component by tightening screws into the threaded holes and against the coupling component. The remedial component of the present invention may be a conventional screw, a laminar hook, or a lock pin with a specified angle. A plurality of remedial components may be used in combination with one coupling component of the present invention depending on the position and the symptom of the deformed vertebra and the surgical requirements. In the preferred arrangement, the coupling components used in the present invention may include a single threaded rod or a plurality of threaded rods joined as an one-piece component by blocks having threaded bores into which the rods are received. The foregoing features, objectives and advantages of the present invention will be better understood by studying the following detailed description of the preferred embodiments, in conjunction with the drawings provided herein. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an exploded perspective view illustrating a vertebral locking and retrieving system constructed according to one of the preferred embodiments of the present invention. Fig. 1(a) shows an element of the vertebral locking and retrieving system of Fig. 1 in a different perspective view. Figs. 2(a)-2(c) show a series of correction procedures of a deformed vertebra by means of the vertebral locking and retrieving system shown in Fig. 1. Fig. 3 shows an exploded perspective view of a vertebral locking and retrieving system constructed according to another preferred embodiment of the present invention. Figs. 4(a)-4(c) show a series of correcting procedures of a deformed vertebra by means of a third preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, the vertebral locking and retrieving system of the present invention can be made of orthopedic materials, such as the iron-based stainless steel 316LVM, the titanium-based material Ti-6-4, and an alloy of chromium, molybdenum and cobalt. The number of lock pins used is of course dependent on the surgical requirements. The lock pin of the present invention is characterized in that its receiving mount and its threaded end portion form a specified angle, such as 175° , 170° , or 165° , with a respective deflection plane angle being 5° , 10° , 15° , so as to meet the angular requirements of various vertebrae. Furthermore, with the employment of different combination of lock pins having the above-mentioned deflection plane angles of 5° , 10° , 15° , a slipped vertebrae can be properly retrieved to have an appropriate angle consistent with normal human anatomy, such as 0° , 5° , 10° , 15° , 20° (5° +15° ), 25° (10° +15° ), and 30° (15° +15° ). This is something beyond the reach of the prior art systems. In addition, working with the prior art system, a surgeon would have to depend entirely on his or her own judgement and clinical experiences to determine the locking angle of the deformed vertebra. On the other hand, the present invention permits a surgeon to study in advance, before operating on the patient, the X-ray negatives with regard to the locking angles of the patient's vertebrae so as to select the most suitable lock pin to use. Referring to Fig. 1, the vertebral locking and retrieving system embodied in the present invention is shown comprising mainly a lock pin 10, a threaded rod 20, a block 30, a remedial screw 40, and a plurality of nuts 50, 51, 52, 53, and 54. The lock pin 10 is composed of a threaded end portion 11, a receiving horseshoe-type fork 12 having a recess 14 on each lateral side thereof, and screw holes 13. The threaded end portion 11 of the lock pin is used to lock the normal vertebra immediately adjacent to the deformed vertebra under treatment. The block 30 is provided with a through hole 32, a plurality of small threaded holes 33, and a large threaded bore 31 (see Figure 1(a)) used to engage with the threaded rod 20. The remedial screw 40 comprises a screw end 41 intended to be secured to the deformed vertebra, a threaded end 42 to be placed through the through hole 32 of the block 30, and a stopping protrusion 43, located between the screw end 41 and the threaded end 42, intended for use in stopping the block 30. The remedial screw 40 and the block 30 are components serving to correct and restore the deformed vertebra as will be discussed more fully below. The nuts 50 and 51 are used to fixedly attach lock pin 10 to threaded rod 20, wherein the nuts 50, 51 are mounted on the screw rod 20 and threaded into recesses 14 of fork 12 seperately when screw rod 20 extends through the slot defined by the horseshoe shape of fork 12. The nut 52 is driven against the block 30 to maintain the position of the block 30 on the threaded rod 20. The block 30 and the remedial screw 40 are fastened securely by means of nuts 53 and 54. If necessary, additional reinforcing screws (not shown) may be provided to secure the engagement between the lock pin 10 and threaded rod 20 by tightening the reinforcing screws into screw holes 13 of lock pin 10 and against the threaded rod 20. Now referring to Fig. 2(a), the fourth segment of the lumbar vertebrae is shown slipping from a normal, desired position prior to tightening of nuts 50 and 51 into the recesses 14 of locking pin 10. However, the slipped segment of the lumbar vertebrae is restored to its desired position of curvature relative to other normal and healthy segments of the lumbar vertebrae as a result of the tightening action of nuts 50 and 51, as shown in Fig. 2(b). This is possible because the lock pin 10 is designed with a specified curvature (as discussed above) permitting the lock pin to negotiate and cooperate with a given segment of the lumbar vertebrae. Now, as shown in Fig. 2(c), the nut 52 has been tightened against block 30 so as to restore a normal clearance between the slipped vertebra and the rest of the normal and healthy segments of the lumbar vertebrae. As nuts 53 and 54 are screwed respectively into their appropriate positions (i.e. from the Fig. 2(b) position to the Fig. 2(c) position), the slipped vertebra of the lumbar vertebrae is retrieved to its normal position. Another preferred embodiment of the present invention is illustrated in Fig. 3 wherein like numerals are used to designate elements corresponding to the above described embodiment. The lock pin 10, which is composed of a threaded end 11, a receiving fork 12, and screw holes 13, is again used to secure the vertebrae immediately adjacent to the deformed vertebra. A connecting block 30 is provided with an 8-shaped through hole 32 and threaded bores 31 and 31'. Threaded rods 20 are threadably received within respective threaded bores 31 and 31' of block 30. The remedial screw 40 is intended to remedy the deformed vertebra and is similar in structure to the one shown in Fig. 1. In this embodiment, however, two lock pins 10 and two threaded rods 2 are fastened together to form a unitary body by means of nuts 50, 51, 52 and 53. The two threaded rods 20 and the connecting block 30 are fixedly secured together by threading nuts 54 and 55 against the block 30. In the meantime, the nuts 56 are used to couple the block 30 with the remedial screw 40 with the 8-shaped through hole 32 permitting a slight adjustment of remedial screw 40 relative to the axis defined by threaded rods 20. The connecting block 30 and/or the threaded rods 20 can be constructed with a specific angle for enabling the system to cooperate with the curvature of the deformed vertebra. Now referring to Figs. 4(a), 4(b) and 4(c), a third embodiment of the present invention is shown comprising two lock pins, one threaded rod as the coupling component and two sets of nuts. These components have not been labeled in Figures 4(a)-4(c), however, it should be clear that the structure is directly analogous to the connection of locking pins 10 to their respective threaded rods 20, 30 and 31 in the prior embodiments described. One of the lock pins is used to serve as a remedial component and is secured to the upper or the lower vertebra immediately adjacent to the deformed vertebra. In Fig. 4(a), the deformed vertebra is shown along with the present locking and retrieving embodiment implanted but which has not been securely fastened. In Fig. 4(b), the lock pins are secured to appropriate positions on the threaded rod as a result of tightening actions of two sets of nuts. Therefore, a lock pin with a specified angle is able to work to lock and retrieve the deformed vertebra. Upon completion of such treatment, all vertebrae in question have been restored to their respective normal positions, as show in Fig. 4(c). Based on the above discussion, it can readily be seen that the vertebral locking and retrieving system of the present invention is characterized in that it comprises lock pins, threaded rods, and nuts, all of which can be selectively employed in accordance with the position of the deformed vertebra, the symptoms of the deformed vertebra and the surgical requirements. For example, if the deformed vertebra happens to be the fourth vertebra of the lumbar vertebrae, the vertebral locking and retrieving system of the present invention shown in Fig. 1 functions effectively. In such a case, one threaded rod with the connecting block serves as the coupling component while a threaded screw is used as the remedial component. In addition, a plurality of nuts are used to work as locking components (see FIG. 1 and its corresponding text). In treating some slipped lumbar vertebrae, two threaded studs united by one connecting block are used as the coupling component for two lock pins and one threaded screw as in the Fig. 3 embodiment. In the case of vertebral fracture or camel back, one threaded rod may be used to serve as the coupling component to interconnect two lock pins, one of which is used to work as a remedial component (see Figs. 4(a), 4(b) and 4(c), and the corresponding text). In order to achieve a better surgical treatment, the present invention can also be employed in conjunction with numerous bone reinforcing devices known in the prior art, such as a cross bridging system. From the above description, it can readily be seen that the present invention is characterized in that it comprises at least one lock pin which is designed with a specified angle enabling the lock pin to cooperate with the specific curvature of the deformed vertebra under treatment, and that its various components can be used in different combinations on the basis of the surgical requirements and the symptom of the deformed vertebra under treatment. Furthermore, the present invention serves to simplify the surgical operation in such ways that it does not require of a surgeon to make a large incision, thereby minimizing the risk of an excessive bleeding by the patient receiving treatment; the patient's ability to move about is not seriously compromised by the surgical operation; and the patient's nervous system is less vulnerable to the pressure exerted thereon by the implanted system. The embodiments of the present invention described above are to be considered in all respects as merely illustrations of principles of the present invention. Accordingly, the present invention is to be limited only by the scope of the following claims.

Claims: A vertebral locking and retrieving device for use in retrieving a deformed vertebra and maintaining the deformed vertebra in a normal, healthy position comprising: at least one locking pin (10) having a threaded portion (11) at one end thereof adapted to be secured to a normal, healthy vertebra and an integrally formed receiving mount (12) at the other end thereof, said threaded portion (11) defining a longitudinal axis, said receiving mount (12) being formed at a specific angle to said axis; said angle excluding 0° and 180° degrees respectively a remedial component (40) adapted to be secured at one end (41) thereof to one of a deformed vertebra located immediately adjacent to said normal, healthy vertebra or to a vertebra immediately adjacent to the deformed vertebra but different from said normal, healthy vertebra to which said at least one locking pin (10) is secured; coupling means, comprising a rod (20, 30), for interconnecting said at least one locking pin (10) and said remedial component (40), said rod (20) having first and second threaded ends; and fastening means (50, 51) for fixedly securing said at least one locking pin (10) and said remedial component (40) to said coupling means (20, 30), said fastening means (50, 51) comprising a pair of nuts (50, 51) which are threadably attached to said rod (20) on opposite sides of said receiving mount (12), the nuts being adapted to properly retrieve a vertebrae as a result of the tightening action of the nuts (50, 51). A vertebral locking and retrieving device as claimed in claim 1, characterised in that said receiving mount (12) of said at least one locking pin (10) is horseshoe-shaped thereby defining a slot through which said rod (10) extends. A vertical locking and retrieving device as claimed in claims 1 or 2, characterised in that said receiving mount (12) is formed with recesses (14) about opposite lateral sides of said slot, said pair of nuts (50, 51) being tightened into said recesses (14). A vertebral locking and retrieving device as claimed in one of the claims 1 to 3, characterised in that said one end (41) of said remedial component (40) is threaded and the other end (42) of said remedial component (40) is connected to said coupling means. A vertebral locking and retrieving device as claimed in one of the claims 1 to 4, characterised in that said coupling means (20, 30) includes a block (30), said first and second threaded ends of said rod (20) being fixedly secured, by said fastening means (50, 51), to said receiving mount (12) of said at least one locking pin (10) and said block (30) respectively, the other end (42) of said remedial component (40) being fixedly secured to said block. A vertebral locking and retrieving device as claimed in claim 5, characterised in that said remedial component (40) includes a stop member (43) formed intermediate the ends (41, 42) thereof, said block (30) includes a hole (32) through which the other end (42) of said remedial component (40) projects such that said block (30) engages said stop member (43) when said remedial component (40) is fixedly secured to said block (30). A vertebral locking and retrieving device as claimed in claim 6, characterised in that the other end (42) of said remedial component (40) is threaded and said fastening means comprises at least one nut (53, 54, 56) which is threadably received on said other end (42) of said remedial component (40) such that said block (30) is sandwiched between said at least one nut (53, 54, 56) and said stop member (43). A vertebral locking and retrieving device as claimed in one of the claims 1 to 3, characterised in that said remedial component comprises a second locking pin.

Inventors: LIN CHIH-I, LIN, CHIH-I
Applicants: LIN CHIH I, LIN, CHIH-I
Application year: 1992
Main classification: A61B17
IPC codes: A61B17, A61F2