IMPROVED SPINAL RETRACTOR

Abstract: An improved spinal retractor frame (10) is disclosed. The retractor frame (10) includes detachable blades (100) which are self-engaging, automatically aligning, and rapidly attachable. The blades (100) are mounted on hinged portions (26, 27) which are pivotally attached to the arms (14, 16) of the retractor frame (10).

Description: BACKGROUND The performance of surgery requires that a retractor hold out of the way all tissues down to the actual surgical site. When performing a posterior approach to the thoracic or lumbar spine, it is necessary to retract very large and strong paraspinal musculature masses. Because of the differences in the size of patients and the relative mass of the muscles along various portions of the spine, it would be necessary to have a series of retractors with permanently attached blades or a series of blades that could be attached or removed as needed from a basic blade-holding retractor frame. However, to keep the retractor blades from ejecting from the wound under the pressures generated by the muscle retraction, it is necessary to have the blades both diverge from the center line distally, and further to have large sharp teeth at a right angle to the longitudinal access of the blades so as to lock the blade tips beneath the muscle masses. If the blades are divergent distally and in addition are splayed, then even with the retractor fully closed, the blades, if pre-attached to the retractor, would not be insertable into the wound as the outside of the tips of the blades would be further apart than the wound is wide. Therefore, retractors having pre-fixed blades must compromise the blade contour to fit in the wound by having less divergent and less angulated blades. Such a configuration significantly diminishing the ability to function as a deep wound retractor. Thus, spinal retractors with attachable blades have been devised. At present, there are essentially two types of large spinal retractors with attachable and removable blades. Such retractors and blades are shown in Figures 10 and 11. The first type (shown in Figure 11) consists of a blade with a rectangular shaped opening at the top into which the retractor arms can be slid to hold the blade. While this does allow the blade to be inserted into the wound first and the retractor arms then attached, there can be great difficulty in attaching the blades to the retractor arms as both blades must be engaged simultaneously which requires that the blades and the arms of the retractor be opened to exactly the same width. Further, the blades must be parallel to each other and to the retractor and at the same time must protrude from the wound to exactly the same height. Further, the blades must be absolutely perpendicular to the spine, and not be rotated. Achieving all of these conditions at the same time can be quite difficult and time consuming. There is also a retractor set which uses a rectangular open box-like attachment method, where the blades are strips of metal of similar widths and different lengths such that a series of strips are attached to each arm until a whole blade is essentially constructed, contoured to the particular patient. However, since the blades are attached to the retractor prior to insertion, the blades cannot be optically divergent thereby defeating at least one of the two major advantages sought to be obtained from the use of the attachable blades. The second type of large spinal retractor currently in use (Figure 10) utilizes a set of attachment posts protruding from the retractor arms which then engage a series of corresponding holes on the top surface of the blades. However, when these blades are placed within the wound first and then an attempt is made to attach the retractor, there is considerable difficultly in aligning the blades and achieving the necessary three dimensional parallelism so as to attach the blades to the retractor. Furthermore, the exposed pegs and locking mechanism pose a threat to the surgeon as it is possible to rupture a glove on the exposed mechanism. SUMMARY OF THE INVENTION The present invention is a spinal retractor consisting of a large gear operated frame and a series of detachable, modular, and complimentary blades especially designed to facilitate attachment of the blades to the retractor without compromise to the angulation of the blades and consistent with optimal function. the retractor frame has a solid spine which is ratcheted, and one fixed arm and one movable arm attached perpendicularly to the spine. The movable arm is moved by a gear driven mechanism, and secured with a spring loaded lock which engages the ratchet of the spine. The retractor is opened and closed with a handle that is removable so that it will protrude during the surgery. Both arms are hinged proximate the junction to the frame to allow the retractor frame and its arms to contour to the shape of the patient, assuring a low profile when in use. The blades are widely divergent deeply and have teeth splaying outward beyond the divergence of the blades, substantially at right angle to the vertical plane of the blades themselves. The arms have a depression or cutout portion along one side of substantially their entire length. The blades have a substantially U-shaped configuration along their upper portion for engaging the corresponding depression or cutout on the arms. The separation of the arms results in the automatic, three dimensional alignment of the blades so as to firmly engage the blades on the arms. OBJECTS OF THE INVENTION It is a purpose of the present invention to provide for a spinal retractor and blade set that is easier and faster to use. It is another purpose of the present invention to provide an improved spinal retractor and blade set that is more efficient, both in executing its purpose and in its method of attachment of the blades to the retractor. It is another purpose of the present invention to provide for an improved spinal retractor and blade set that is modular in design so as to allow pairs of blades to be assembled in various combinations to enhance the overall variability. It is still another purpose of the present invention to provide for an improved spinal retractor and blade set that is stronger than any presently existent spinal retractor. It is yet another purpose of the present invention to provide for an improved spinal retractor and blade set that is of a low profile and without surface projections so as to minimize interference with, and risk to, the surgeon. It is another purpose of the present invention to provide from an improved spinal retractor and blade set in which the blades divergence beyond previously existing retractors. It is another purpose of the present invention to provide for an improve spinal retractor and blade set that is capable to opening a wound more widely than any previously existent spinal retractor. These and other objects of the present invention will be apparent from a review of the following specification and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWING Fig. 1 is a perspective view of the retractor. Figs. 2a, 2b and 2c are perspective views of various blade configurations used with the retractor of Figure 1. Fig. 3 is a perspective view of the retractor and blades in relation to the spine demonstrating the use of the hand crank to open the retractor. Fig.4 is an cross sectional view of the lumbar spine demonstrating the cross sectional relationship between the retractor blades and the retractor arms. Fig 5 is a top view of the retractor and blades situated in the thoracic spine. Fig 6 is a partial sectional view of the retractor ratchet mechanism and lock mechanism. Fig. 7 is a partial sectional view of the "fixed" arm. Fig. 8 is a partial sectional view of the ratchet and lock mechanism. Fig. 9 is a side sectional view of the hand crank and its relationship to the gear. Fig. 10 is a perspective view of one version of the prior art. Fig. 11 is a perspective view of a second version of the prior art. DETAILED DESCRIPTION OF THE DRAWINGS Referring to figure 1 the retractor frame 10 is shown in perspective view. The retractor frame 10 comprises a spine 12 having a rectangular cross section. A first fixed arm 14 is affixed to the upper portion of the spine 12 and a second movably arm 16 is movably attached to the spine 12. The two arms 14 and 16 have a substantially rectangular cross section and parallel to one another and in the same plane. The spine 12 has a ratchet 18 along its inside surface, which engages a complementary ratchet mechanism on the movable arm 16. The ratchet mechanism 20 (shown in figures 6, 8 and 9) on the movable arm is lockable by lock 22 against movement. The two arms 14 and 16 consists of a first rigid portion and a second hinged portion 26 and 27. The hinged portion 26 and 27 are connected to the first rigid portion 24 and 25 by hinges 28 and 29. The hinged portions 26 and 27 have an elongated cutout or groove portion 36 and 38 along opposing sides of the hinged portions of the arms. The cutout or depressions extends substantially along the entire length of the edge of the hinged portion 26 and 27 of arms 14 and 16. A hand crank 32 engages the drive gear opening 34 in the ratchet mechanism 20 for turning the gear mechanism to cause the movable arm 16 to move up and down the spine 12. Referring to Figures 6, 8 and 9, the ratchet mechanism 20 is shown in detail. The ratchet mechanism 20 consists of drive gear 40 having a drive gear opening 34 for engagement with the crank 32. The drive gear 40 is complementary to the ratchet 18 along the spine 12. The lock 22 is pivotable about pivot pin 42 and biased in a position wherein the lock engages the ratchet 18 by spring 43 enclosed within recess 45 in the rigid portion 25 of arm 16. A thumb depressing portion 44 is at one end of the lock and the other end of the lock 22 consists of a ratchet engaging tip 46 complementing the ratchet 18 of the spine 12, and biased at an angle so that the lock prevents closing of the arms when engaged, but not the opening of the arms. Referring to Figure 7, the detail of the hinge 28 is shown. The hinge in both the fixed arm 14 and the movable arm 16 consists of a central pin 48 passing through larger aligned openings 58. The pin 48 may be held in place by screw threads or other conventional means. Referring to Figure 2(a) -2(c) alternative forms of blades are shown for use with the retractor. The blades 100 ar used in pairs. One blade is used in association with the fixed arm 14 of the retractor frame 10 and the second blade is used in association with the movable arm 16 of the retractor 10. The blade 100 has a substantially central planar portion 102, substantially perpendicular teeth 104 on the lower end and a U-shaped engaging portion 106 at its upper end. The depth of the U shaped engaging portion 105 of the blade 1-00 is approximately 3/4 inches, slightly smaller than the width of the cutout 36 and 38 of the retractor arms 14 and 16. In the preferred embodiment the cutout has a depth of approximately 1/2 inch. The teeth 104 are substantially perpendicular to the planar surface 102 and are approximately 1/2 inch long. The blades are also made of heavy stainless steel, so as to resist bending by the muscles. The blades themselves are approximately 1/4 inch thick and are approximately 4 inches wide. The spine 12 is approximately one foot long and the maximum extension of the opening between the arms in use is approximately 6 inches. The length of the arms are approximately 6 inches long. The recess or cutout portion 36 and 38 permits the arms 14 and 16 when the blades 100 are attached to the arms 36 and 38. Otherwise, the upper leg 108 of the blades 100 would extend beyond the top surface of the arms 36 and 38. The width of the planar portion at the lower end may vary depending on the particular application of which the blades are being used, such as is shown in Figures 2b and 2c. Referring to figures 3-5 the apparatus is shown in use on the patient. In Figure 3 the retractor is shown in the spine, with the hand crank 32 about to be engaged. The teeth of the blades are illustrated as holding the muscles out of the way. In Figure 4 the blades are shown inside sectional view, showing in detail the engagement of the arms with the blades. In Figure 5, a top view of the retractor frame and blades during an operation. METHOD OF USE Blades of the appropriate depth as determined by the size of the patient are inserted on either side of the spine against and beneath the spinal musculature. The blades are inserted in pairs on opposite sides of the wound. The retractor frame is then placed between the blades in a close position. The retractor is opened and when any part of the retractor arm rides over the inner portion of the U-shaped blade engagement area, the retractor arm will then de-rotate, align, and engage the blades as the retractor is opened. To remove the retractor, the crank is again inserted. The lock mechanis is released and the retractor allowed to close until the blades are disengaged. The retractor may then be removed, followed by the blades. In the preferred embodiment, the retractor is made of heavy metal, such as stainless steel giving the retractor substantial weight to resist the torques that are applied by the muscle of the body. While the present invention has been described in reference to the preferred embodiment of the invention, it is recognized that other embodiments of the present invention may be made without departing from the present inventive concept.

Claims: What is claimed is: 1. A surgical retractor comprising: a spine member, said spine member having a pair of arms substantially perpendicular to the spine and parallel to one another, said arms being hingedly attached to said spine. 2. The retractor of claim 1 in which said arms have means for removably holding a blade comprising a cutout along at least one edge of at least one of said arms. 3. The apparatus of claim 1 in which at least one of said arms is fixed in relationship to said spine and at least one other of said arms is movable in relationship to said spine. 4. The apparatus of claim 3 in which said movable arm is movable by a gear mechanism. 5. The apparatus of claim 2 in which said arms have a substantially rectangular cross section and said cutout is along the side of each arm away from the other arm. 6. The apparatus of claim 2 in which said cutout extends substantially the length of aid arm. 7. The apparatus of claim 1 including at least one pair of blades, said blades slidably engaging said arms. 8. The apparatus of claim 7 in which said blades comprise a substantially planar member, said planar member having teeth at one end and a U shaped engaging member at the other end for engaging said arm. 9. The apparatus of claim 8 in which the opening of said U shape engaging member faces said arm and said U shape member extends substantially along the entire length of said blade. 10. The apparatus of claim 8 in which said U shape has a width slightly larger than the width o the portion of the arm in contact with the blade. 11. The apparatus of claim 8 in which the legs of said U shape member are perpendicular to said planar member. 12. The apparatus of claim 11 in which said blade is maintained on side arms in a perpendicular orientation in relationship to the arm. 13. Blades for use with a retractor comprising a substantially planar member, said planar member having teeth at one end and a U-shaped engaging member at the other end for engaging the arms of a retractor. 14. The apparatus of claim 13 in which said U shaped engaging member has a width slightly larger than the width of the arms of a retractor. 15. The apparatus of claim 12 in which the legs of said U shape member are perpendicular to said planar member. 16. The apparatus of claim 13 in which said U shape engaging member maintains said blade in a perpendicular orientation in relationship to the arms of the retractor.

Inventors: MICHELSON GARY KARLIN, MICHELSON, GARY, KARLIN
Applicants: MICHELSON GARY K, MICHELSON, GARY, KARLIN
Application year: 1989
Main classification: A61B17
IPC codes: A61B17