Patent ID: 12256916

DETAILED DESCRIPTION

FIG.1depicts a retractor system100that includes, generally, a retractor device102, a guide element104, and a driver106. The retractor device102includes a handle108coupled to an elongate element110to which two blades118,120are secured. In some embodiments, the handle108is a removable handle that is selectively coupled to or removed from the elongate element110. The blades118,120may be secured directly to the elongate element110or secured with one or more armatures114,116. As shown inFIG.1, in one embodiment, the armatures114,116extend from a side of the elongate element110, such that a surgical opening created by the blades118,120may be accessible by the surgeon performing the operation without obstruction by the elongate element110. One or both of the armatures114,116may be movably secured to the elongate element110. In this particular embodiment, the driver106is used to actuate a moving mechanism, in this case, to rotate a gear that engages with a rack along the elongate element110. Actuation of the moving mechanism can operate to separate the armatures114,116, and thus separate the blades118,120. This mechanism is more dearly depicted inFIG.3B. Other moving mechanisms may be used to move the blades118,120relative to the elongated elements. For example, lead screw/nut mechanisms and linear rail/slide mechanisms may be used. Certain of these systems may require additional locking elements, as described below. One of the retractor blades118,120(in one embodiment, the posterior blade120) defines an opening for receipt of the elongate guide element104, the use of which is described below. Additionally, one or both of blades118,120may be configured to removably receive one or more shims.

The guide element104and a guide element insertion device202are depicted inFIG.2. In the depicted embodiment, the guide element104is an elongate dissector having a generally D-shaped profile, although the present disclosure contemplates other elongated dissector profile shapes, including elliptical, trapezoidal, oblong, triangular, and the like. The blunt tip204and profile shape of the guide element104simplifies the insertion process and also assists in splitting the psoas along the plane of the muscle fibers. A probe206may be placed in a channel206aor opening extending lengthwise along the guide element104. After insertion, once a desired position is confirmed, a K-wire can be placed via the same or a second channel to dock the guide element104to the disc space. In an alternative embodiment, the K-wire may be already inserted into the guide element104, prior to the guide element104being inserted. An opening, bore, or channel210in the guide element104sized to receive the K-wire, and discrete from the probe channel, is depicted inFIG.2. This opening210may be a fully closed channel, a partially closed channel, or some combination thereof Depending on the embodiment, the K-wire channel210may be located in or on the guide element104(as shown), in armature114or armature116, or in an anterior retractor blade118or a posterior retractor blade120.

The guide element104may include a number of notches214that provide an engagement surface for an insertion device202. In the depicted embodiment, forceps including radio-lucent arms212are used for insertion. Other types of insertion devices may be used, or the guide element104may also be positioned by hand, if desired. The radio-lucent forceps arms212typically will not show during fluoroscopy, but radio-opaque markers208may be included on the arms202to assist in positioning. Radio-opaque markers208placed at other locations indicating the positions/locations of certain elements may be utilized. Additionally, the guide element104may also be radio-lucent. Radio-opaque markers also may be positioned proximate the center and anterior border of an implant to be inserted during the surgical procedure.

FIGS.3A-3Bdepict various views of a dissector-type guide element104used in conjunction with a retractor device102. As initially described above, the driver is used to actuate a moving mechanism, in this case, to rotate a gear302that engages with a rack304along the elongate element110. A locking element302aa may prevent further movement of the gear when engaged, by for example, engaging the rack304. The guide element104is received within an opening306defined by at least one of the retractor blades118,120. In the depicted embodiment, the opening306is located in the posterior blade120. Alternatively or additionally, an opening306may be located in the anterior blade118or in either or both of the armatures114,116. Once the guide element104is inserted into the skin surface and muscle tissue to a desired depth, the retractor device102is moved M along an axis A so as to receive the guide element104in the opening306. As most readily seen inFIG.3B, the flat portion of the generally D-shaped guide element104is facing anteriorly (i.e., towards the blades118,120), such that the retractor device102is slid over the guide element104with the face surfaces of the opposing retractor blades118,120facing each other. Since the guide element104is located in the opening306defined in the exterior surface of the posterior blade120, all or substantially all of both blades118,120are located on the same side of the guide element104, unlike dilator/retractor systems that locate the blades118,120on both sides of (or around) dilators.FIG.3Adepicts a distal end310of the posterior retractor blade120, along with the guide element104located along a rear surface of the blade120. In general, the distal ends310of the retractor blades118,120should not be inserted lower than the tip204of the guide element104but the blades118,120may be inserted further, if desired.

FIG.3Balso depicts the retractor lock302a,which is used to fix the position of the posterior blade armature116along the elongate element110and to prevent inadvertent movement of the armature116, and therefore the blade120, along the elongate element110. In thin ease, the retractor lock302amay be disengaged prior to rotating the gear302with the driver106, as described above in the context ofFIG.1. The retractor lock302athen may be reengaged to prevent further movement of the armature116. The retractor lock302amay engage with the elongate element110, either at the rack304itself or at a separate point located on the elongate element110. Each armature114,116includes an articulating arm connection308, such as that described below. Once the retractor blades118,120are inserted into the psoas muscle, an articulating arm (not shown) may be connected to either the anterior blade armature114or the posterior blade armature116. An opposite end of the articulating arm is connected to a fixed point (typically on the operating table), to hold the retractor device102in position during operation of the opening mechanism. When the articulating arm is connected to the anterior blade armature114, actuation of the opening mechanism will move the posterior blade120along the elongate element110, towards the handle108. When the articulating arm is connected to the posterior blade armature116, actuation of the opening mechanism will move the anterior blade118in a direction away from the posterior blade120. Note that in this second configuration, since the posterior blade armature116is connected to the elongate element110, each of the anterior blade118, its armature114, the elongate element110, and the handle108move relative to the fixed posterior blade120as the opening mechanism is operated. Depending on the location of the guide element104and desired position of the surgical corridor, an operator may make the articulating arm connection308as desired. It should be noted that by fixing the position of the posterior blade120with the articulating arm, the possibility of compressing nerves and/or restricting the blood flow due to pressure on the transverse process is reduced or eliminated. The two-blade, flat-blade design assists in splitting the psoas muscle along the plane of the muscle fibers, thereby reducing trauma.

It should also be noted that either or both of the blades118,120may be configured with any number of openings, channels, or other structures that allow for receipt of an electrode probe, such that the location of nerves may be determined during insertion of the retractor device102, during opening of the blades118,120, or after opening of the blades118,120. Use of such probes for identifying nerve proximity and direction is well-known within the field of spinal surgery, and will not be further described herein. Additionally, the same or other channels may be used to hold a light source used to illuminate the surgical corridor.

FIG.4depicts a partial side view of the retractor system100. In some embodiments, the retractor blades118,120of the device may be fitted with one or more shims that serve particular purposes during surgery. Widening shims may be used to help ensure muscle tissue does not encroach on the surgical corridor. Lengthening shims may be used to effectively lengthen the depth of penetration of the blades118,120. Intradiscal shims May be used to penetrate the disc space of the spine so as to access the disc and hold one of the blades118,120of the retractor device102in place, relative to the spine. As depicted inFIG.4, the anterior blade118and the posterior blade120may be separated slightly so as to allow access to the space between with a shim inserter402, which is used to guide a shim404down to the appropriate location along the blade.FIGS.5A and5Bdepict a wrap-around shim502and an internally-confined shim504, respectively. Either shim122type may be used in conjunction with the retractor device102, on either or both of the anterior blade118and the posterior blade120. Once the shim(s) are installed, it may be desirable to remove either or both of the K-wire and the guide element104prior to opening the retractor blades118,120to the desired maximum position. Either shim502,504may include a ratchet506that engages with a rack508located on the blade120, such that the shim502,504may be inserted to a desired depth and held in place. Both of the shims502,504depicted inFIGS.5A and5Bare intradiscal shims that include a tip510that may be inserted into the disc space, to help fix the location of the blade120internal to the body. The rack508may extend along a portion of an inner channel512of the blade118,120, or may extend the entire length of the inner channel512.

FIGS.6A-6Bdepict the embodiment of the retractor device102shown in an open position, creating a surgical corridor within the muscle tissue. Of course, a functional surgical corridor need not require the blades118,120to be opened to a maximum distance. If desired or required, a frame612may be placed between the blades118,120to provide support to the distal ends310of the blades118,120. This may be useful, for example, should the surrounding tissue force an inward deflection of the blade ends310and thus cause a narrowing of the surgical corridor. The frame612may be held in place via the inner channels512located in either or both of the blades118,120, and may be inserted with an insertion element610(e.g., a pair of forceps).FIGS.6A and6Balso depict a lengthening shim614located on the anterior blade118.

Movement of the blade relative to the elongate element110is described with reference toFIG.6A. The elongate element110defines an operational axis O. Each front face of the anterior blade118and the posterior blade120define a plane. For clarity, only anterior plane P is depicted inFIG.6A. Each of the blades118,120also includes a reference point606located thereon. The reference point606may be located on the face surface602or rear surface604of the blade, or may be a defined point thereon, for example, a center of gravity, a blade tip, a radio-opaque reference point, etc. Additionally, the reference point606need not be a distinct physical point. Instead, that term is used herein to further define movement of the blades118,120. Regardless, a predetermined reference point606is identified on the rear surface604of the posterior blade120inFIG.6A. For the purposes of this example, the articulating arm described above is connected to the anterior blade armature114. Therefore, as the moving mechanism (the gear302) is operated, the posterior blade120moves toward the handle108. In that regard, the reference point606moves along an axis of movement M that is generally parallel to the operational axis O and generally orthogonal to the anterior blade plane P. This configuration of axes and planes, as well as the substantially flat configuration of the blades118,120, helps ensure muscular separation along the muscle fiber plane, thereby limiting muscular trauma. Of course, if the articulating arm is connected to the posterior blade armature116, similar movement of the anterior blade118occurs. A reference point located on the anterior blade118moves along an axis generally parallel to the operational axis O, as well as generally orthogonal to the posterior blade plane. Also, if the articulating arm is connected to the posterior blade armature116, the intradiscal shim504depicted may be inserted into the intradiscal space to help further limit movement of the posterior blade120. In general, the tip510of the intradiscal shim504is not extended beyond the blade tip310during movement of the blade118,120on which the intradiscal shim504is installed.

FIG.7depicts a method700of using a retractor system in a surgical procedure. Although the method is described in the context of lateral-approach spinal surgery, it should be noted that the systems and methods described herein may be used in virtually any surgery where limited muscular and/or nerve trauma is desired. In surgeries where limited, controlled separation of muscle fibers is desirable, the retractor system described herein may be particularly advantageous. Further, while shown inFIG.7as a series of Operations, method700can combine operations or eliminate operations altogether. For example, operations related to nerve monitoring and probes may be omitted in the event the surgeon does not elect to use nerve monitoring. Initially, a guide element is inserted (operation702) into the area of interest (in this case, the psoas muscle) and directed toward the target tissue, organ, or skeletal structure (in this case a vertebrae or disc space). An electrode probe may be located in the guide element prior to insertion and introduced at the same time as the guide element. The probe may then be energized and the feedback monitored (operation704) to check for nerve response (e.g., in the lumbar plexus). In certain surgeries, the guide element is positioned so as to be centered near the anterior one-third of the intravertebral disc. The guide element may be repositioned (operation706) as required or desired, generally until a suitable location is found. Electrode monitoring (operation704) may be repeated to confirm the location is safe for the surgery to continue. In a particular embodiment, the guide element is repositioned (operation706) posteriorly in small increments until the desired location is found and nerve monitoring indicates the location is safe for surgery to continue. In a particular embodiment, the guide element is positioned as far posterior as possible, so that subsequent retractor blade movement will be a movement of only the anterior blade away from the posterior blade.

Once the proper position is confirmed, the guide element may be swept (operation708) side-to-side so as to create a plane in the psoas muscle and make an initial opening into which a retractor device will be inserted. Thereafter, a K-wire may be inserted (operation710) via the guide element toward the target region, and secured relative to the disc space. Prior to insertion of the retractor device, the monitoring probe may be removed (operation712) from the guide element and inserted into one of the retractor blades. This would allow for monitoring of nerve response during insertion of the retractor, which may be desirable in certain situations. Alternatively, a second monitoring probe may be used with the retractor. Due to the unique configuration of the retractor system, the retractor blades are inserted on the same side of the guide element, into the opening formed by the earlier sweeping movement thereof. As described above, this helps separate the psoas muscle along the Muscle fibers. Additionally, by inserting both blades on the same side of the guide element, the guide element can be positioned on the posterior side of the desired surgical site, with the posterior blade also being positioned on the posterior side of the desired surgical site.

As the retractor device is inserted (operation714) into the initial surgical opening, the guide element is inserted into the opening defined by the retractor blade, typically the posterior retractor blade. After inserting the retractor blade a certain distance into the muscle, the probe may be energized and the feedback monitored to confirm location and/or proximity of the blades relative to nearby nerves (operation716). This blade position monitoring operation716need not be performed however. Regardless, once the retractor blades reach their desired depth of penetration, an articulating arm may be connected (operation718) to either of the posterior blade armature and the anterior blade armature. As described above, connection to either of the armatures will dictate which of the armatures moves and, accordingly, the direction of separation of the retractor blades, (i.e., anteriorly or posteriorly). Once secured to the armature, a number of different actions may be taken in virtually any order to complete the surgical procedure. For example, the blades may be spread slightly and a shim may be inserted (operation720). A shim may accomplish any of the purposes described above, and in one embodiment is used to farther anchor the distal end of one of the blades to help secure it place relative to a desired surgical site. Thereafter or alternatively, the blades may be spread further and a frame may be inserted (operation722) to provide rigidity to the distal ends of the retractor blades. Again, this blade separation may occur from just a single blade moving while the other blade remains generally in place. At any point, desired surgical procedures may be performed (operation724), such as a partial or full discectomy, and insertion of an implant per the surgeon's discretion. Of course, surgical procedures may be performed at any time after insertion of the blades, and the shims and/or the frame may be inserted at any time during the procedure, as required. For example, if a surgical procedure is initiated without insertion of a frame, but during the procedure, the surgical corridor begins to contract, the surgeon may then insert the shim and/or the frame. Additionally, the locking mechanism may be locked and unlocked as required during the procedure.

Materials utilized in the manufacture of the retractor system may be those typically used in surgical equipment. Stainless steel, titanium, and other robust metals that may be sterilized may be used. In applications where fluoroscopy is desirable or required during the procedure (e.g., in the spinal surgery procedures described herein), radio-lucent materials may be particularly desirable. In those applications, aluminum, anodized aluminum, and rigid polymers may be utilized. Carbon fiber-reinforced polymers may be particular useful, as they are lightweight, extremely strong, and may be sterilized. Of course, retractor systems utilizing a combination of materials may be used. For example, radio-lucent materials may be used for the blades and less expensive radio-opaque material may be utilized for the elongate element and armatures. Additionally, radio-lucent materials may be impregnated in discrete locations with radio-opaque materials such that position of certain parts of the system may be visible during procedures, without impeding overall visibility.

While there have been described herein what are to be considered exemplary and preferred embodiments of the present technology, other modifications of the technology will become apparent to those skilled in the art from the teachings herein. The particular methods of manufacture and geometries disclosed herein are exemplary in nature and are not to be considered limiting. It is therefore desired to be secured in the appended claims all such modifications as fall within the spirit and scope of the technology. Accordingly, what is desired to be secured by Letters Patent is the technology as defined and differentiated in the following claims, and all equivalents.