Patent Description:
<FIG> is an illustration of the axial section of the human spine with certain structures and regions to be referenced throughout the present disclosure. With reference to the compass rose of <FIG>, it is noted that the anatomical directions will also be referenced in accordance with standard medical convention; i.e., medial (M) to the center of the body, lateral (L) to the sides of the body, anterior (A) to the front of the body, and posterior (P) to the rear of the body. The spine includes a series of vertebrae (V) separated by intervertebral discs (IVD). <FIG> shows a singular intervertebral disc (IVD) positioned superior a singular vertebra (V) such that the intervertebral disc (IVD) is viewable in plane. A vertebral space (VS) may be considered a volume of the anatomy including the vertebra (V) and adjacent the vertebra (V). Further surrounding the vertebra (V) is various musculature and vasculature. Anterior the anterior aspect of the vertebra (V) and the intervertebral disc (IVD) is the inferior vena cava (IVC) vein and aorta (AO) artery, which serve as the primary cardiovascular vessels of the body. The identified musculature includes the psoas major (PM) generally lateral to the vertebra (V) and the intervertebral disc (IVD), and the erector spinae (ES) generally posterior to the same. Fascia (FAS) and fatty tissue overlay the musculature, and overlying skin (OS) overlays the fascia (FAS).

The vertebra (V) includes the spinous process (SP) and transverse processes (TP) with laminae (LAM) generally extending therebetween. A pedicle (PED) extends between facets (superior articular facet (SAF) identified) and the body of the vertebra (V). The structures collectively form a portion of the vertebra (V) surrounding the spinal cord (SC) extending in the cranial-to-caudal direction. The intervertebral disc (IVD) includes the annulus fibrosis (AF), an outer fibrous ring forming a fibrocartilaginous joint with the vertebra (V) to allow for slight movement while acting as a ligament for holding the vertebrae together. The annulus fibrosis (AF) may define the intervertebral disc space (IVDS), within which the nucleus pulposus (NP) is disposed. The nucleus pulposus (NP) is gel-like in structure and configured to distribute pressure in all directions within the intervertebral disc (IVD) under compressive loads.

As mentioned, of particular interest is the preparation of the intervertebral disc space (IVDS) with a minimally invasive approach. As is common to MIS, and is illustrated in <FIG>, positioned consecutively are a K-wire (not shown), a plurality of dilators <NUM>, and a retractor <NUM> to provide a working channel <NUM> to a surgical site <NUM> at the region of interest. While some visualization may be realized through the working channel <NUM> provided through the retractor <NUM>, it is readily appreciated that meaningful visualization within the intervertebral disc space (IVDS) or vertebral space (VS) may be unachievable, in particular, the lateral aspects and the posterior aspect, for example. Further, even with placement of a visualization device that may be capable of accessing the aforementioned areas (such as an endoscope, for example), blood and bone debris may obstruct the field of view, particularly after resection of the tissue with the use of a surgical instrument <NUM>, such as shown in <FIG>.

Referring now to <FIG>, a surgical system <NUM> in accordance with a first variation of the present disclosure is shown. The surgical system <NUM> may include a retractor <NUM> having a proximal end <NUM>, a distal end <NUM>, an inner surface <NUM>, an outer surface <NUM>, and a central axis <NUM> extending between the distal end <NUM> and the proximal end <NUM>, in which the distal end <NUM> is configured to be positioned within the patient to provide a working channel <NUM> to the surgical site <NUM> and the proximal end <NUM> defines an opening <NUM> open to ambient. In some variations, such as when the operation being performed is a transforaminal lumbar interbody fusion (TLIF), the distal end <NUM> of the retractor <NUM> may be positioned adjacent to the intervertebral disc space (IVDS) after the removal of the facet joint to provide access to the intervertebral disc for resection of desired tissue. Additionally, in some endoscopic procedures, such as those pertaining to the spine, the surgical site <NUM> cannot be subjected to substantial barometric pressure. In some instances, the surgical site <NUM> may not be pressurized due to physiological constraints within the region, while in other instances it may be impractical. Therefore, in certain variations, the opening <NUM> of the retractor <NUM> is open to ambient to prevent exposing the surgical site <NUM> to greater than atmospheric pressures by allowing excess matter (air, for example) in the retractor <NUM> to escape through the opening <NUM> as opposed to building up pressure within the surgical site <NUM>.

The surgical system <NUM> may also include an inflow source <NUM> in fluid communication with the retractor <NUM> for providing a fluid to the surgical site <NUM> to form a volume of fluid <NUM> disposed in the surgical site <NUM> and the retractor <NUM>, as well as an outflow source <NUM> in fluid communication with the retractor <NUM> for removing a volume of fluid from the surgical site. An exemplary inflow source is disclosed in <CIT>. The inflow source <NUM> and/or the outflow source <NUM> may include, for example, a vacuum source, or a positive pressure pump, such as a peristaltic pump. The inflow source <NUM> and the outflow source <NUM> may be in fluid communication with the retractor by tubing coupled to the retractor <NUM>, for example. In certain configurations, the fluid is a suitable fluid such as water, saline, and the like, preferably a liquid. Among other advantages, the volume of fluid <NUM> may improve visualization of the surgical site <NUM> from an endoscope <NUM> or improve cooling of a surgical instrument <NUM> and the nearby tissue, illustrated in <FIG>.

With continued reference to <FIG>, the surgical system <NUM> may further include a sensor <NUM> coupled to the retractor <NUM> for providing a sensor input signal <NUM> based on a level of fluid disposed in the retractor <NUM>. The level of fluid may pertain to a height or a volume of the fluid extending up the retractor <NUM> from the distal end <NUM>. The surgical system <NUM> may also further include a controller <NUM> in communication with at least one of the sensor <NUM>, the inflow source <NUM>, or the outflow source <NUM> to control a flow rate of fluid being provided to the surgical site <NUM> by the inflow source <NUM>, an outflow rate of fluid being removed from the surgical site <NUM> by the outflow source <NUM>, or a combination thereof based on the sensor input signal <NUM>, such that a threshold level of fluid <NUM> is maintained in the retractor <NUM> and at the surgical site <NUM>. The threshold level of fluid <NUM> pertains to a desired range of fluid to be maintained in the retractor <NUM> and includes at least one of a minimum threshold <NUM>' or a maximum threshold <NUM>". The minimum threshold <NUM>' may be defined such that it ensures a desired minimum level of fluid is at the surgical site <NUM> and within the retractor <NUM> during operation of the surgical system <NUM>. For example, the minimum threshold <NUM>' may be defined such that the fluid level is maintained at or above the distal end <NUM> of the retractor <NUM>, for example, one-third, one-half, or three-quarters upwardly along the central axis <NUM> of the retractor <NUM>. In another example, minimum threshold <NUM>' may be an approximate minimum steady state volume of fluid to be maintained within the retractor <NUM>, for example, <NUM>, <NUM>, <NUM>, <NUM>, etc. The maximum threshold <NUM>" may be defined, for example, such that it ensures fluid does not overflow from the retractor <NUM> during operation of the surgical system <NUM>.

Still referring to <FIG>, the controller <NUM> may be configured to receive a user input signal corresponding to the threshold level of fluid <NUM> disposed in the retractor <NUM> for controlling the outflow source <NUM> and/or the inflow source <NUM> based on the user input signal. For example, the user input signal may pertain to the desired level of fluid to be maintained at the surgical site <NUM> and within the retractor <NUM> during operation of the surgical system <NUM>. The user input signal may be provided by a user input device (not shown), such as a button, GUI, knob, slider, etc. that provides the operator with an interface capable of providing the user input signal to the controller <NUM> in order to modulate operational parameters of the surgical system <NUM>, such as the threshold level of fluid <NUM>.

In an example of the operational behavior of the surgical system <NUM>, a user input signal pertaining to an increase in the threshold level of fluid <NUM> received by the controller <NUM> may result in the controller <NUM> controlling the outflow source <NUM> to temporarily decrease the outflow rate, while also controlling the inflow source <NUM> to maintain the inflow flow rate. Alternatively, for example, the controller <NUM> may control the inflow source <NUM> to temporarily increase the inflow flow rate while controlling the outflow source <NUM> to maintain the outflow rate in order to maintain the volume of fluid <NUM> within the increased threshold level of fluid <NUM>.

Conversely, a user input signal pertaining to a decrease in the threshold level of fluid <NUM> provided to the controller <NUM> may result in the controller <NUM> controlling the outflow source <NUM> to temporarily increase the outflow rate while controlling the inflow source <NUM> to maintain the inflow flow rate. Alternatively, for example, the controller <NUM> may control the inflow source <NUM> to temporarily decrease the inflow flow rate while controlling the outflow source <NUM> to maintain the outflow rate in order to maintain the volume of fluid <NUM> within the decreased threshold level of fluid <NUM>.

Additionally or alternatively, the controller <NUM> may also be configured to receive a user input signal pertaining to a turnover rate of fluid disposed in the retractor <NUM>. Based on the user input signal pertaining to the turnover rate, the controller <NUM> is capable of controlling at least one of the outflow source <NUM> or the inflow source <NUM>. The turnover rate of the fluid disposed in the retractor <NUM> may pertain to a synchronized inflow rate of fluid to the surgical site <NUM> coordinated with the outflow rate from the surgical site <NUM> to ensure a continuous supply of fresh fluid to the surgical site <NUM> to clear any debris and facilitate clear visualization. For example, with the coordinated inflow rate and outflow rate of fluid being provided, a swirling motion of the fluid in the surgical site <NUM> may result that moves debris away from surgical site <NUM>.

The turnover rate may be adjusted up or down by the user based on situational needs. For example, a user input signal pertaining to an increase in the turnover rate may result in the controller <NUM> controlling the outflow source <NUM> and the inflow source <NUM> to increase the outflow rate and the inflow rate, respectively. The increase in the turnover rate may be advantageous for situations where the debris being generated at the surgical site <NUM> is not evacuated from the surgical site <NUM> as quickly as desired.

Conversely, a user input signal pertaining to a decrease in the turnover rate may result in the controller <NUM> controlling the outflow source <NUM> and the inflow source <NUM> to decrease the outflow rate and the inflow rate, respectively. The decrease in the turnover rate may be advantageous for situations where little debris is being generated at the surgical site <NUM>, and the swirling motion of the fluid unnecessarily obstructs visualization.

Referring to <FIG>, in a second variation, the surgical system <NUM> may include, amongst other components, an outflow source <NUM> in fluid communication with the retractor <NUM> for removing a volume of fluid and having an outflow sensor <NUM> for providing an outflow input signal <NUM>. In certain configurations, the outflow source <NUM> may be a vacuum system <NUM>. The vacuum system <NUM>, for example, may be a surgical waste management system sold under the tradename NEPTUNE manufactured by Stryker Corporation (Kalamazoo, Mich. ) and disclosed in commonly owned <CIT>; <CIT>; <CIT>; <CIT>; <CIT>, among others. The outflow sensor <NUM> may be a pressure sensor, flowrate sensor, or a combination thereof and may be used to generate the outflow input signal <NUM> pertaining to operational characteristics of the outflow source <NUM>. For example, the operational characteristics of the outflow source <NUM> may include a pressure differential being generated by outflow source <NUM> or a mass/volumetric flowrate of matter being removed from the surgical site <NUM> by the outflow source <NUM>.

The surgical system <NUM> of the aforementioned second variation may further include a fluid level sensor <NUM> (similar to the aforementioned sensor of the first variation), a first controller <NUM>, and a second controller <NUM> in communication with the first controller <NUM> and the outflow source <NUM>, such that the first controller <NUM> controls the inflow source <NUM> based on the received outflow input signal <NUM> and the fluid level sensor input signal <NUM>. In certain variations, the first controller <NUM> is in communication with at least one of the inflow source <NUM>, or the outflow source <NUM> to control a flow rate of fluid being provided by the inflow source <NUM>, an outflow rate of fluid being removed by the outflow source <NUM>, or a combination thereof based on the fluid level sensor input signal <NUM> and the outflow input signal <NUM>. For example, the outflow input signal <NUM> may be provided to the controller(s) to provide feedback regarding the operational characteristics of the outflow source <NUM> in order to compensate for the operation of the outflow source <NUM> in order to maintain the threshold level of fluid <NUM> in the retractor <NUM>.

Advantageously, the aforementioned feedback allows the controller(s) to anticipate changes in the level of fluid <NUM> due to the operation of the outflow source <NUM> faster than could be detected by the fluid level sensor <NUM>. More specifically, changes in the operational characteristics of the outflow source <NUM> precede any resulting change in the level of fluid <NUM> in the retractor <NUM>. Thus, the fluid level sensor <NUM> may experience a delay in conveying a change in the level of fluid in the retractor <NUM> in response to a change in an operational characteristic of the outflow source <NUM>. Therefore, the provided feedback of the operational characteristics of the outflow source <NUM> facilitates a smoother response to transient operation of the surgical system <NUM>.

In a third variation, illustrated in <FIG>, the surgical system <NUM> may include, amongst other components, an inflow source <NUM> having an inflow sensor <NUM> for providing an inflow input signal <NUM>, and an outflow source <NUM> (similar to aforementioned outflow source in previous variations) for removing a volume of fluid from the surgical site <NUM>. The inflow sensor <NUM> may include a pressure sensor, flowrate sensor, or a combination thereof and may be used to generate the inflow input signal <NUM> pertaining to operational characteristics of the inflow source <NUM>. For example, the operational characteristics of the inflow source <NUM> may include a pressure differential being generated by the inflow source <NUM> or a mass/volumetric flowrate of fluid being provided to the surgical site <NUM> by the inflow source <NUM>.

The surgical system <NUM> of the aforementioned third variation may also include the fluid level sensor <NUM> (similar to aforementioned fluid level sensor in previous variations) coupled to the retractor <NUM> for providing a fluid level sensor input signal <NUM> responsive to the level of fluid <NUM> in the retractor <NUM>, a first controller <NUM>, and a second controller <NUM> in communication with the first controller <NUM> and the inflow source <NUM>, such that the first controller <NUM> controls the outflow source <NUM> based on the inflow input signal <NUM> and the fluid level sensor input signal <NUM>. In certain variations, the first controller <NUM> is in communication with at least one of the inflow source <NUM>, or the outflow source <NUM> to control a flow rate of fluid being provided by the inflow source <NUM>, an outflow rate of fluid being removed by the outflow source <NUM>, or a combination thereof based on the fluid level sensor input signal <NUM> and the inflow input signal <NUM>. For example, the inflow input signal <NUM> may be provided to the controller(s) to provide feedback regarding the operational characteristics of the inflow source <NUM> in order to compensate for the operation of the inflow source <NUM> in order to maintain the threshold level of fluid <NUM> in the retractor <NUM>.

Advantageously, the aforementioned feedback allows the controller(s) to anticipate changes in the level of fluid <NUM> due to the operation of the inflow source <NUM> faster than could be detected by the fluid level sensor <NUM>. More specifically, changes in the operational characteristics of the inflow source <NUM> precede any resulting change in the level of fluid <NUM> in the retractor <NUM>. Thus, the fluid level sensor <NUM> may experience a delay in conveying a change in the level of fluid in the retractor <NUM> in response to a change in an operational characteristic of the inflow source <NUM>. Therefore, the provided feedback of the operational characteristics of the inflow source <NUM> facilitates a smoother response to transient operation of the surgical system <NUM>.

In a fourth variation, illustrated in <FIG>, the surgical system <NUM> may include, amongst other components, an inflow source <NUM> having an inflow sensor <NUM> for providing an inflow input signal <NUM>, and a first outflow source <NUM> (similar to aforementioned outflow source in previous variations) in fluid communication with the retractor <NUM> for removing a volume of fluid from the surgical site <NUM> and having an outflow sensor <NUM> for providing an outflow input signal <NUM>. The surgical system <NUM> may also include a second outflow source <NUM> that may be in fluid communication with an outflow outlet <NUM> of a surgical instrument <NUM> having a cutting member <NUM> for removing a volume of fluid from the surgical site <NUM>. In certain variations, the second outflow source <NUM> may be, for example, a centralized wall suction system, which in some configurations may not be controllable by the surgical system <NUM>. The surgical system <NUM> may further include a second controller <NUM> in communication with the first controller <NUM> and the first outflow source <NUM> such that the first controller <NUM> controls the inflow source <NUM> to control a flow rate of fluid being provided by the inflow source <NUM> and the second controller <NUM> controls the first outflow source <NUM> to control an outflow rate of fluid being removed by the first outflow source <NUM> based on at least one of the sensor input signal <NUM>, the inflow input signal <NUM>, or the outflow input signal <NUM> such that a threshold level of fluid <NUM> is maintained in the retractor <NUM> to compensate for sensed changes due to operation of the second outflow source <NUM>.

In an illustrative scenario, with the inflow source <NUM> and first outflow source <NUM> being controlled by the controller <NUM> to maintain a threshold amount of fluid <NUM> in the retractor <NUM> and the surgical site <NUM>, the user may insert the surgical instrument <NUM> in fluid communication with the second outflow source <NUM>, for example, a shaver coupled to a vacuum. Because the second outflow source <NUM> may be electronically independent of the first outflow source <NUM>, the controller <NUM> may not anticipate the suction associated with the shaver being introduced into the volume of the fluid <NUM>. The insertion of the shaver and operation of the vacuum may initially decrease rapidly the level of fluid <NUM> disposed in the retractor <NUM>. It is important that the volume of the fluid <NUM> not be entirely aspirated such that no fluid remains. Therefore, the controller <NUM> is configured to compensate for this in a rapid and responsive manner. The controller <NUM> may do so by increasing the inflow rate of the inflow source <NUM>, decreasing the outflow rate of the first outflow source <NUM>, or a combination thereof. The new parameter(s) may be maintained while the shaver remains operational within the anatomy. Similarly, once the shaver is removed from the retractor <NUM>, the new parameter(s), if left unchanged, may result in an undesired amount of fluid rapidly accumulating within the retractor <NUM> or overflowing from the retractor <NUM>. The controller <NUM> is configured to rapidly and responsively compensate for this by decreasing the inflow rate of the inflow source <NUM>, increasing the outflow rate of the first outflow source <NUM>, or a combination thereof. The aforementioned functionality advantageously provides for ensuring the minimum threshold of fluid <NUM>' is maintained in the retractor <NUM>, and the maximum threshold of fluid <NUM>" is not exceed without requiring specific user intervention or input. In other words, the surgeon need not stop the procedure to adjust the parameter(s) of the surgical system <NUM> prior to insertion or removal of the shaver. Furthermore, the functionality may be particularly well suited with off-the-shelf or standalone surgical instruments that are configured to be operated independently (i.e., not electronically integrated into the surgical system <NUM>).

While in some variations, multiple controllers are used to operate various components of the surgical system <NUM>, it is contemplated that a single controller, for example having a plurality of sub-controllers, could be used to provide a similar capability.

Referring now to <FIG>, in one variation, the aforementioned sensor <NUM> may include an electrical fluid sensing member <NUM> disposed about the inner surface <NUM> or outer surface <NUM> of the retractor <NUM> and provides the sensor input signal <NUM> to the aforementioned controller(s). The electrical fluid sensing member <NUM> may be configured to sense impedance or resistance, such as the impedance or resistance of liquid in the retractor <NUM>. In an example not according to the claims, shown in <FIG>, the retractor <NUM> may further include a measurement vessel <NUM> in communication with the retractor <NUM> and the sensor <NUM> includes a pressure sensor <NUM> that is configured to measure pressure within the measurement vessel <NUM> and provides the sensor input signal <NUM> to the aforementioned controller(s). In certain variations, the sensor input signal <NUM> may pertain to the height or volume of the fluid extending up the retractor <NUM> ascertained by the sensor <NUM>. The aforementioned controller(s) may compare the threshold level of fluid <NUM> and the sensor input signal <NUM>, and based on the comparison of the threshold level of fluid <NUM> and the sensor input signal <NUM>, the controller(s) may control at least one of the outflow source <NUM> or the inflow source <NUM> to maintain the volume of fluid <NUM> within the threshold level of fluid <NUM>.

Referring now to <FIG>, a variation of the retractor <NUM> is shown. The retractor <NUM> may include at least one of an inflow port <NUM> or an outflow port <NUM>. The inflow port <NUM> is adapted to receive an inflow tube <NUM> in fluid communication with an inflow source <NUM> to define an inflow path <NUM>, and the outflow port <NUM> is adapted to be coupled to an outflow tube <NUM> in fluid communication with an outflow source <NUM> to define an outflow path <NUM>. <FIG> shows the inflow port <NUM> and the outflow port <NUM> coupled to the retractor <NUM>, and more particularly near the distal end <NUM> of the retractor <NUM>. For illustrative purposes, the inflow port <NUM> and outflow port <NUM> are positioned on opposite sides of the retractor <NUM>, but other locations and arrangements are within the scope of the present disclosure. The inflow port <NUM> and outflow port <NUM> are adapted to be removably coupled to the inflow tube <NUM> and outflow tube <NUM>, respectively, with a Luer fitting, or other suitable connection providing fluid communication between the inflow source <NUM> and outflow source <NUM>, respectively.

<FIG> shows the retractor <NUM> defining an inflow-outflow channel <NUM> at least partially separate from the working channel <NUM>. The inflow-outflow channel <NUM> of the illustrated variation is defined between the inner surface <NUM> and the outer surface <NUM> of the retractor <NUM>. In other words, the inflow-outflow channel <NUM> may be an annular space extending between the inner surface <NUM>, the outer surface <NUM>, and the distal and proximal ends <NUM>, <NUM> of the retractor <NUM>. The inflow-outflow channel <NUM> at the proximal end <NUM> is adapted to be placed in fluid communication with at least one of the inflow port <NUM> or the outflow port <NUM>. The inflow-outflow channel <NUM> at the distal end <NUM> may be open such that the fluid flows out the distal end <NUM>. In the variation illustrated in <FIG>, the inflow-outflow channel at the distal end <NUM> is closed, and the inner surface <NUM> includes fenestrations <NUM> providing fluid communication between the inflow-outflow channel <NUM> and the working channel <NUM>. The fenestrations <NUM> may be, for example, apertures circumferentially arranged about at least a portion of the inner surface <NUM>, and in particular, a lower portion of the inner surface as shown in <FIG> shows the inflow-outflow channel <NUM> in fluid communication with each of the inflow tube <NUM> and the outflow tube <NUM>. In one variant, the annular space defining the inflow-outflow channel may include partitions (not shown) extending a length of the retractor <NUM> such that the partitions provide fluid separation between the inflow fluid being received from the inflow tube <NUM>, and the fluid to be removed by the outflow tube <NUM>.

It is contemplated that other manners for providing fluid communication between the inflow-outflow channel <NUM> and the retractor <NUM> are contemplated. The retractor <NUM> may also include a coupling member <NUM> configured to be coupled to the retractor <NUM>, as shown in <FIG>. The coupling member <NUM> may be a plug <NUM> sized to be snugly inserted within the working channel <NUM> of the retractor <NUM> and secured by interference fit. An access opening <NUM> may be defined through the coupling member <NUM> with the access opening <NUM> suitably sized to receive one or more surgical instruments, for example, the cutting instrument <NUM> or the endoscope <NUM>. The retractor <NUM> may also further include an inflow tube <NUM> and an outflow tube <NUM> each coupled to the coupling member <NUM>. Each of the inflow and outflow tubes <NUM>, <NUM> extend distally from the coupling member <NUM>. A distal end <NUM> of the inflow tube <NUM> is spaced at a desired distance from the coupling member <NUM>, for example near the distal end <NUM> of the retractor <NUM>. Likewise, a distal end <NUM> of the outflow tube <NUM> is spaced at a desired distance from the coupling member <NUM>, for example near the distal end <NUM> of the retractor <NUM>. <FIG> shows the distal end <NUM> of the inflow tube <NUM> positioned distal to the distal end <NUM> of the outflow tube <NUM>. The arrangement may facilitate the outflow tube <NUM> siphoning the debris-filled fluid from the retractor <NUM> with the inflow tube <NUM> providing the fresh fluid closer to the surgical site <NUM>. The arrangement may also provide the aforementioned swirling effect to move debris away from the field of view of the endoscope <NUM>. In the illustrated embodiment, the inflow and outflow tubes <NUM>,<NUM> are positioned in a side-by-side configuration, and further positioned near the inner surface <NUM> of the retractor <NUM>. With the inflow and outflow tubes <NUM>,<NUM> positioned near the inner surface <NUM>, substantially an entirety of the working channel <NUM> remains unobstructed for the passage of, among other items, the surgical instrument <NUM> and/or the endoscope <NUM> through the access opening <NUM>.

Referring now to <FIG>, in another variation, the aforementioned retractor <NUM> may further include a tilt sensor <NUM> in communication with any of the aforementioned controller(s) and configured to generate a signal pertaining to an orientation of the retractor <NUM>. Based on the sensed orientation of the retractor <NUM>, the aforementioned controller(s) may control at least one of the outflow source <NUM> or the inflow source <NUM>. For example, if the sensed orientation is beyond a defined deviation from upright, the controller(s) may automatically prevent operation of the surgical system <NUM>. For example, the tilt sensor <NUM> may include an accelerometer, a gyroscope, or another sensor for determining orientation. Likewise, the surgical system <NUM> may include additional or separate accelerometer(s) or gyroscope(s) configured to detect sudden movement of the retractor <NUM> of the surgical system <NUM>, which is desired to remain relatively stable during the surgical operation. If a sudden movement is detected beyond a predetermined threshold, the controller(s) may terminate operation of the surgical system <NUM>. Still further, the surgical system <NUM> may include a device sensor (not shown) configured to prevent inadvertent operation of the surgical system <NUM> unless the device sensor is coupled to the retractor <NUM>. In one example, the device sensor may be a clip with a readable tag (e.g., radio frequency identification (RFID) tag) that, once coupled to the retractor <NUM> and detected by a complementary reader, permits operation of the surgical system <NUM> in the manners described throughout the present disclosure. Conversely, if the readable tag is not detected by the complementary reader, operation of the surgical system <NUM> is prevented.

The surgical system <NUM> may include a retention member <NUM> adapted to maintain the position of the retractor <NUM> relative to the patient or other desired structure within the surgical site. <FIG> shows the retention member <NUM> including a flange rigidly coupled to the retractor <NUM>. The retention member <NUM> may be operably coupled to a robot, for example the MAKO® Robotic-Arm Assisted Technology (MAKO Surgical Corp. Lauderdale, Flor. ) utilizing a surgical navigation system (not shown) to precisely maintain the pose (i.e., position and orientation) of the retractor <NUM>, particularly in response to any movement of the patient.

In another variation, a deflectable valve (not shown) may be coupled to the retractor <NUM> and disposed within the opening <NUM>. In one example, the deflectable valve is a duckbill valve. In one example, the deflectable valve is a diaphragm formed from material (e.g., an elastomer) adapted to be impaled by the surgical instrument(s) <NUM>. A partial seal between the valve and the instrument(s) may be provided such that the level of fluid maintained in the retractor <NUM> remains at or near atmospheric pressure, yet egress of the fluid from the working channel <NUM> through the opening <NUM> is prevented. It is further contemplated that an illumination source (not shown) may be coupled to the retractor <NUM> and configured to provide illumination through the working channel <NUM>.

The present disclosure also pertains to various methods of performing a surgical procedure at a surgical site <NUM> of a spine of a patient. In one variation shown in <FIG>, the method includes the steps of: positioning a retractor <NUM> in a patient's back such that the distal end <NUM> of the retractor <NUM> is located adjacent to a surgical site <NUM> at the patient's spine, providing a fluid from an inflow source <NUM> to the surgical site <NUM> to form a volume of fluid <NUM> disposed in the surgical site <NUM> and the retractor <NUM>, sensing a level of a fluid disposed in the retractor <NUM> using a sensor <NUM>, and controlling the inflow source <NUM>, an outflow source <NUM>, or a combination thereof based on the sensed level of fluid in the retractor <NUM> such that fluid is maintained in the retractor <NUM>. For example, the volume of the fluid <NUM> maintained in the retractor <NUM> may be a threshold level of fluid <NUM>. Among other advantages, maintaining fluid in the retractor <NUM> may assist a surgeon with visualization of the surgical site <NUM> from an endoscope <NUM> or improve cooling of a surgical instrument <NUM> (not shown in <FIG>) and the nearby tissue.

In certain variations of the various methods of the present disclosure, the method further includes a step of receiving user input to a controller <NUM> pertaining to the threshold level of fluid <NUM> to be maintained in the retractor <NUM> and controlling the outflow source <NUM> and the inflow source <NUM> based on the user input signal. The user input signal may be provided by a user input device (not shown), such as a button, GUI, knob, slider, etc. that provides the operator with an interface capable of providing the user input signal to the controller <NUM> in order to modulate operational parameters of the surgical system <NUM>, such as the threshold level of fluid <NUM>. For example, the user input signal may pertain to the desired level of fluid to be maintained at the surgical site <NUM> and within the retractor <NUM> during operation of the surgical system <NUM>. Furthermore, in certain additional variations of the method of the present disclosure, the method further includes a step of receiving user input to the controller <NUM> pertaining to a turnover rate of fluid and controlling the outflow source <NUM> and the inflow source <NUM> based on the user input signal. The turnover rate of the fluid disposed in the retractor <NUM> may pertain to a synchronized inflow rate of fluid to the surgical site <NUM> coordinated with the outflow rate of fluid from the surgical site <NUM> to ensure a continuous supply of fresh fluid to the surgical site <NUM> to clear any debris and facilitate clear visualization, the rate of which may be adjusted up or down by the user based on situational needs.

With reference to <FIG>, in a further variation of the methods of the present disclosure, the aforementioned step of positioning the retractor <NUM> may further include the steps of: positioning consecutively a K-wire (not shown), a plurality of dilators <NUM> sequentially increasing in diameter, and a retractor <NUM> having a distal end <NUM> and a proximal end <NUM> such that the plurality of dilators <NUM> and the distal end <NUM> of the retractor <NUM> are at a location adjacent to the surgical site <NUM> at the patient's spine, and removing the plurality of dilators <NUM> and the K-wire such that the retractor <NUM> remains to provide a working channel <NUM> to the location adj acent to the surgical site <NUM> at the patient's spine.

In some endoscopic procedures, such as those pertaining to the spine, the surgical site <NUM> cannot be subjected to substantial barometric pressure. In some instances, the surgical site <NUM> may not be pressurized due to physiological constraints within the region, while in other instances it may be impractical. Therefore, in another variation, the step of providing a fluid to the surgical site <NUM> via the inflow source <NUM> further includes providing the fluid to the surgical site <NUM> without exposing the surgical site <NUM> to a pressure greater than atmospheric pressure (e.g. <NUM> atm).

Referring to <FIG>, <FIG>, and <FIG>, a distal end of the endoscope <NUM> may be inserted through the retractor <NUM> and submerged within the volume of fluid <NUM>. One exemplary endoscope <NUM> suitable for the present application includes the <NUM> HD <NUM>-Chip Camera manufactured by Stryker Corporation (Kalamazoo, Mich. It is contemplated that a camera (or an illumination source) may be coupled near a distal end of a nosetube of the surgical instrument <NUM> (or at or near a distal end of the outer tube of the shaver). It is further contemplated that the lens or imaging sensor may be a component of a steerable assembly, i.e., configured to articulate within the anatomy of the patient in response to an input from the user. One exemplary steerable camera suitable for the present application is disclosed in commonly owned International Publication No. <CIT>. Alternatively, a microscope may be used in lieu of the endoscope <NUM>.

The endoscope <NUM> of <FIG>, <FIG> and <FIG> includes a shaft defined between the distal end and a proximal end opposite the distal end. At or near the distal end of the endoscope <NUM> is the lens or image sensor in communication with the camera at or near a handpiece of the endoscope <NUM>. The proximal end of the shaft may be coupled to the handpiece adapted to be grasped and manipulated by a physician. The distal end of the shaft, and more particularly the lens or the image sensor, is submerged within the volume of fluid <NUM>. In certain configurations, the surgical instrument <NUM> may be operated to rotate the cutting member <NUM> within the field of view of the endoscope <NUM> during at least a portion of the surgical procedure. With the inflow or outflow being removed from the volume of fluid <NUM>, the fluid turnover minimizes obstruction of the field of view of the endoscope <NUM>, further realizing the benefits of performing the tissue resection within the volume of fluid <NUM>. For example, with the inflow or outflow being provided or removed, a swirling effect may result that moves debris away from the lens or the image sensor at the distal end of the endoscope <NUM>.

In some variations, the method may further include the step of submerging a cutting member <NUM> of a surgical instrument <NUM> within the volume of fluid <NUM> and operating the surgical instrument <NUM> submerged within the volume of fluid <NUM> to resect tissue. As used herein, submerged means to be positioned within the volume of fluid <NUM> and/or positioned beneath the surface of the fluid. The surgical instrument <NUM> is operated to rotate the cutting member <NUM> within the volume of fluid <NUM> to resect tissue within the intervertebral disc space (IVDS). For surgical instruments <NUM> with the cutting member <NUM> including a bur head, the method may include submerging the entirety of the bur head. The benefits of performing the tissue resection within the volume of fluid <NUM> are readily realized with the nearly an entirety of the cutting member <NUM> and the surrounding tissue being in direct contact with the fluid, thereby maximizing heat transfer to the fluid. Potential elevation of the temperature of the cutting member <NUM> and the surrounding tissue is limited, which may improve cutting efficiency of the cutting member <NUM> and/or lessen the likelihood of surrounding tissue damage.

Another exemplary surgical instrument <NUM> of particular interest is a shaver. The shaver includes outer tube and a tubular drive shaft rotatably disposed within the outer tube with the cutting member <NUM> defined between windows within each of the outer tube and the tubular drive shaft. An outflow outlet <NUM> (see <FIG> and <FIG>) of the surgical instrument <NUM> may be in communication with the windows defining the cutting member <NUM>. The windows are adapted to be submerged within the volume of fluid <NUM> with the surgical instrument <NUM> rotating the tubular drive shaft to resect the tissue. With the outflow outlet <NUM> submerged within the volume of fluid <NUM>, the benefits of powerful suction afforded by shavers are fully realized. An exemplary shaver includes the ESSx® microdebrider system (Stryker Corporation (Kalamazoo, Mich. ) and/or shavers disclosed in commonly owned <CIT>; <CIT>; <CIT>; <CIT>. Other suitable surgical instruments <NUM> may include a router, an electrode for radiofrequency (RF) ablation, a saw or a blade configured to be received by a saw driver, a scalpel, an ultrasonic tip configured to be received by a sonopet, a curette, a rasp, a trocar sleeve, biopsy forceps, ligation devices, tissue staplers, tissue scissors, the S2 πDrive®, Sumex®, Maestro®, Saber, and Aril drill systems, manufactured by Stryker Corporation (Kalamazoo, Mich. ), and/or any other endoscopic cutting device configured to be received by an endo-handpiece.

As described throughout the present disclosure, the surgical system <NUM> includes the surgical instrument <NUM> with the cutting member <NUM> adapted to be submerged within the volume of fluid <NUM> to resect tissue, for example within the intervertebral disc space (IVDS) and/or the vertebral space (VS). The aforementioned bur and shaver systems may be straight or angled. One exemplary surgical instrument <NUM> is disclosed in commonly owned International Publication No. <CIT>. It is further contemplated that the surgical system <NUM> of the present disclosure may be navigation-assisted. For example, one or more navigation markers (not shown) may be coupled to the patient in a suitable location with the navigation markers detectable by an optical camera in the surgical suite, as described in commonly owned <CIT> entirety. The navigation markers may facilitate the determination of an intraoperative position of the cutting member <NUM> of the surgical instrument <NUM> within the intervertebral disc space (IVDS). Additionally or alternatively, each of the surgical instrument <NUM> and the endoscope <NUM> may include components and features of the computer-implemented navigation systems disclosed in commonly owned <CIT> and <CIT> and <CIT>. In addition, the retractor <NUM> may include one or more navigation markers.

The utilization of the surgical instrument <NUM>, the endoscope <NUM>, and the outflow source <NUM> provided by the surgical system <NUM> may lessen or eliminate the need to remove the surgical instrument <NUM> from the intervertebral disc space (IVDS) once positioned therein, a significant improvement over existing methodologies using manual rongeuers discussed previously. Among other benefits, the risk of neural damage to the ascending and/or descending nerve roots is lessened. Further, the improved visualization of the endoscope <NUM> during use of the surgical instrument <NUM> provides for more thorough, targeted removal of the nucleus pulposus (NP) and more thorough, targeted preparation of the endplates in advance of placement of the interbody spacer. Satisfactory preparation of the intervertebral disc space (IVDS) can be confirmed visually without needing to rely on rudimentary methodologies associated with manual instruments without visualization.

The present disclosure described the surgical system <NUM> in the context of certain steps of the transformainal lumbar interbody fusion (TLIF) and laminectomy surgical procedures. However, other spine procedures well suited to be performed within the volume of fluid <NUM> include, but are not limited to, lateral lumbar interbody fusion (XLIF), posterior lumbar interbody fusion (PLIF), foraminotomy, facetectomy, etc. Moreover, the aforementioned systems and methods of performing surgery within the volume of fluid <NUM> may be well suited for other procedures involving other orifices, cavities within the human body, and/or through openings resected through skin and/or bone of the patient during the surgical procedure. Examples include the volume of fluid being provided to the ear cavity, nasal cavity, mouth cavity, or eye cavity. Further examples include the volume of fluid being provided to a craniotomy during neurosurgery, a joint cavity during orthopedic surgery, or a soft tissue void space during cardiothoracic surgery.

Claim 1:
A surgical system (<NUM>) for performing a surgical procedure at a surgical site (<NUM>) of a spine of a patient, the surgical system (<NUM>) comprising:
a retractor (<NUM>) having a proximal end (<NUM>), a distal end (<NUM>), an inner surface (<NUM>), an outer surface (<NUM>), and a central axis (<NUM>) extending between the distal end (<NUM>) and the proximal end (<NUM>), in which the distal end (<NUM>) is configured to be positioned within the patient to provide a working channel (<NUM>) to the surgical site (<NUM>) and the proximal end (<NUM>) defines an opening (<NUM>) open to ambient;
an inflow source (<NUM>) coupled to the retractor (<NUM>) for providing a fluid (<NUM>) to the surgical site (<NUM>) to form a volume of fluid (<NUM>) disposed in the surgical site (<NUM>) and the retractor (<NUM>);
an outflow source (<NUM>) for removing a volume of fluid (<NUM>) having an outflow sensor (<NUM>) for providing an outflow input signal (<NUM>);
a fluid level sensor (<NUM>) comprising an electrical fluid sensing member (<NUM>) disposed about the inner surface (<NUM>) of the retractor (<NUM>), wherein the fluid level sensor (<NUM>) is configured to provide a fluid level sensor input signal (<NUM>) based on a level of fluid (<NUM>) disposed in the retractor (<NUM>); and
a first controller (<NUM>) in communication with at least one chosen from the inflow source (<NUM>) and the outflow source (<NUM>), and configured to control a flow rate of fluid (<NUM>) being provided by the inflow source (<NUM>), an outflow rate of fluid (<NUM>) being removed by the outflow source (<NUM>), or a combination thereof based on the fluid level sensor input signal (<NUM>) and the outflow input signal (<NUM>).