The authors would like to acknowledge all those who donate their bodies for research and keep impacting others after they have gone.

The use of deceased human specimens, for the purposes of developing this method, has been approved by the WellStar Research Institute&#39;s institutional review board and conforms with the ethical guidelines established by the institution&#39;s ethics committee. The specimens used in this method were all formalin-fixed, transected at the T12 vertebral body, and had their abdominal organs and viscera removed.
1. Preparation of the cadaveric specimen and surgical field
<ol>
	<li>Place the previously thawed cadaveric specimen on the surgical table in the supine position and illuminate the field with surgical lights. Cover the specimen with a blanket, sparing the upper and lower abdomen.</li>
</ol>
2. Isolation and identification of key anatomical structures using a ventral approach
<ol>
	<li>Beginning with a ventral approach, use a blade to make a midline incision, cranial to caudal, down to the hypogastric region and directly perpendicular to the anterior-superior iliac spines. Make a transverse cut between the ASIS and proceed to use a surgical blade and scissors to reflect and remove the abdominal musculature and fascia. This will improve visualization and aid in measurement accuracy.</li>
	<li>Identify the transverse processes, lamina, pars interarticularis of lumbar vertebrae L1&#8211;L5, psoas muscles, and the nerve roots of the LP exiting the neuroforamina. Ensure that they are intact and undamaged (Figure 1). If any obvious damage to the hemivertebrae or transverse process is found, do not use the specimen.</li>
	<li>Once all key anatomic structures are identified, carefully turn over the specimen to begin the dorsal approach.</li>
</ol>
3. Further isolation of the transverse processes and obtaining digital photographs for analysis
<ol>
	<li>With the specimen now in the prone position, use a surgical blade, scissors, cobb elevator, and other surgical tools to resect the latissimus dorsi and paraspinal muscles, starting sequentially from the posterior spinous process until reaching the transverse processes.</li>
	<li>Use the cobb elevator and other surgical tools to isolate the TPs from any remaining soft tissue attachments to aid in visualization and accurate measurements.</li>
	<li>With the paraspinal muscles now removed, turn the specimen back to the supine position. Place a surgical ruler parallel to the surgical field and take digital photographs of the intact psoas muscle to demonstrate its relationship to the TP at each vertebral level.</li>
	<li>Once all photographs are taken and deemed of good quality, use a surgical blade to strip the psoas muscle from its medial attachment at each lumbar body and perform a blunt dissection using blunt edged scissors or hemostats to carefully expose the entire lumbar plexus and reflect the psoas muscle laterally.</li>
	<li>With the surgical ruler placed parallel to the surgical field, take additional photographs to capture the relationship of the lumbar plexus to the transverse process at each level.</li>
	<li>Finally, turn the specimen on its side and take additional photographs to demonstrate the relationship of the TP to the LP in the sagittal plane.</li>
</ol>
4. Calibrating and taking measurements using ImageJ software
<ol>
	<li>In the File tab in ImageJ (1.48v, National Institute of Health), select Open and, in the new window that appears, select the photograph to be analyzed.</li>
	<li>With the desired image now open, use the &#34;magnifying glass&#34; tool to zoom in on the surgical ruler in the photograph. Use the line drawing tool to carefully draw a straight line between the margins of a 1-millimeter segment on the ruler.</li>
	<li>Within the Analyze tab in ImageJ, select Set scale&#8230;. In the Set Scale window, set the known distance to 1.00 and the unit of length to mm. Place a check in the box next to Global and click OK. Your measurements will now be calibrated according to the number of pixels per millimeter on the ruler.</li>
</ol>
5. Calculating the &#34;safe zone&#34; for maximal I&#38;D
<ol>
	<li>Using the &#34;line drawing&#34; tool in ImageJ, draw a straight line between the lateral superior tip of each TP to the lateral edge of the psoas at the same level.</li>
	<li>Once the lines are drawn, under the Analyze tab, select measure. A new Results window will open.</li>
	<li>The measurements, in millimeters, will appear in the new window under the Length column in the order taken. Record these numbers.</li>
	<li>Repeat steps 5.1&#8211;5.3 to obtain the following measurements: 
	-Lateral inferior tip of each TP to the lateral edge of the psoas muscle 
	-Lateral superior tip of each TP to the most lateral region of the lumbar plexus at the same level 
	-Lateral inferior tip of each TP to the most lateral region of the lumbar plexus at the same level 
	-Width of the lumbar plexus 
	-Depth of the lumbar plexus from the superior tip of each TP to the lumbar plexus at the same level using the lateral photographs 
	-Depth of the lumbar plexus from the inferior tip of each TP at the same level using the lateral photographs</li>
</ol>
6. Calculating the safe zone for maximal irrigation and debridement using the measurements obtained in Section 5
<ol>
	<li>The safe zone for lateral to medial debridement is defined by the distance from the lateral edge of the lumbar plexus to the lateral edge of the psoas at the same level. To calculate this distance, subtract the distance from the superior and inferior tips of the TP to the lumbar plexus from the distance of the superior and inferior tips of the TP to the lateral edge of the psoas muscle. These values will correspond to the safe zone for lateral to medial debridement, in the coronal plane, at each corresponding level.</li>
	<li>Define the zone of maximal irrigation and debridement in the sagittal plane as the depth of the lumbar plexus, in relation to the TP, at the corresponding level.</li>
</ol>

<ol>
	<li>Bartolo, D. C., Ebbs, S. R., Cooper, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Psoas+abscess+in+Bristol:+a+10-year+review.">Psoas abscess in Bristol: a 10-year review.</a> International Journal of Colorectal Disease. 2, 72-76 (1987).</li><li>Dietrich, A., Vaccarezza, H., Vaccaro, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iliopsoas+abscess:+presentation,+management,+and+outcomes.">Iliopsoas abscess: presentation, management, and outcomes.</a> Surgical Laparoscopy Endoscopy &amp; Percutaneous Techniques. 23, 45-48 (2013).</li><li>Santaella, R. O., Fishman, E. K., Lipsett, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+vs+secondary+iliopsoas+abscess.+Presentation,+microbiology,+and+treatment.">Primary vs secondary iliopsoas abscess. Presentation, microbiology, and treatment.</a> Archives of Surgery. 130, 1309-1313 (1995).</li><li>Yamagami, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Percutaneous+drainage+of+psoas+abscess+under+real-time+computed+tomography+fluoroscopic+guidance.">Percutaneous drainage of psoas abscess under real-time computed tomography fluoroscopic guidance.</a> Skeletal Radiology. 38, 275-280 (2009).</li><li>Tabrizian, P., Nguyen, S. Q., Greenstein, A., Rajhbeharrysingh, U., Divino, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Management+and+treatment+of+iliopsoas+abscess.">Management and treatment of iliopsoas abscess.</a> Archives of Surgery. 144, 946-949 (2009).</li><li>Labrechts, M. J., Wiegers, N. W., Ituarte, F., Shen, F. H., Nourbakhsh, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Safe+zone+for+irrigation+and+debridement+of+psoas+abscess+through+a+dorsal+spinal+approach.">Safe zone for irrigation and debridement of psoas abscess through a dorsal spinal approach.</a> Surgical and Radiologic Anatomy. 40, 1217-1221 (2018).</li><li>Wilkinson, D. J., Piasecki, M., Atherton, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+age-related+loss+of+skeletal+muscle+mass+and+function:+Measurement+and+physiology+of+muscle+fibre+atrophy+and+muscle+fibre+loss+in+humans.">The age-related loss of skeletal muscle mass and function: Measurement and physiology of muscle fibre atrophy and muscle fibre loss in humans.</a> Ageing Research Reviews. 47, 123-132 (2018).</li><li>Aszmann, O. C., Dellon, E. S., Dellon, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomical+course+of+the+lateral+femoral+cutaneous+nerve+and+its+susceptibility+to+compression+and+injury.">Anatomical course of the lateral femoral cutaneous nerve and its susceptibility to compression and injury.</a> Plastic and Reconstructive Surgery. 100, 600-604 (1997).</li><li>Spivak, J. M., Paulino, C. B., Patel, A., Shanti, N., Pathare, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Safe+zone+for+retractor+placement+to+the+lumbar+spine+via+the+transpsoas+approach.">Safe zone for retractor placement to the lumbar spine via the transpsoas approach.</a> Journal of Orthopedic Surgery. 21, 77-81 (2013).</li><li>Reid, J. G., Livingston, L. A., Pearsall, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+geometry+of+the+psoas+muscle+as+determined+by+magnetic+resonance+imaging.">The geometry of the psoas muscle as determined by magnetic resonance imaging.</a> Archives of Physical Medicine and Rehabilitation. 75, 703-708 (1994).</li><li>Hanson, P., Magnusson, S. P., Sorensen, H., Simonsen, E. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differences+in+the+iliolumbar+ligament+and+the+transverse+process+of+the+L5+vertebra+in+young+white+and+black+people.">Differences in the iliolumbar ligament and the transverse process of the L5 vertebra in young white and black people.</a> Acta Anatomica. 163, 218-223 (1998).</li><li>Ilayperuma, I., Nanayakkara, B. G., Hasan, R., Uluwitiya, S. M., Palahepitiya, K. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coracobrachialis+muscle:+morphology,+morphometry+and+gender+differences.">Coracobrachialis muscle: morphology, morphometry and gender differences.</a> Surgical and Radiologic Anatomy. 38, 335-340 (2016).</li></ol>

The authors declare that they have no competing financial interests.

The most critical steps for finding the safe zone for irrigation and debridement of a psoas muscle abscess through a dorsal approach are 1) careful blunt dissection of the lumbar plexus during the ventral and dorsal approach; 2) preservation of the transverse processes during their isolation, as they can be fragile, for better visualization; and 3) calibrating the ImageJ software with the surgical ruler and taking careful measurements to elucidate the relationship between the TP, LP, and psoas muscle.
Surgical instruments used for dissection can be changed according to personal preference; it is crucial however to perform a careful and thorough dissection of the lumbar plexus and to ensure no damage is done to the transverse processes. When taking the photographs, make sure that the ruler is parallel to the field of dissection and that the pictures taken are of high quality. Use of both the cranial and caudal tip of the TP should be included for precise measurements.
A significant limitation of this study is a high probability of psoas muscle atrophy in the cadaveric specimens used. The average age of the specimens used was 80.5 years and cross-sectional area of skeletal muscle has been shown to be negatively correlated with age7. In addition, the cadavers used were formalin-fixed, leading to less tissue pliability as compared to the natural tissue that would be found in a living human being needing an operation. Another limitation is that, because their course can be highly variable after exiting the neuroforamina, the sensory nerves were not included when measuring the lumbar plexus8. Care should still be taken to avoid these nerves when performing I&#38;D of a psoas abscess.
This method focuses on different measurements than previous studies, which may account for the homogenous distance found from the tip of each TP to the lateral edge of the psoas muscle. Previous methods studying psoas anatomy, such as in the studies by Spivak et al., Reid et al., Hanson et al., and Ilayperuma et al., directly measure the width of the psoas muscle9,10,11,12. Compared to the study by Spivak et al., for example, the range of measurements found by measuring from the TP to the psoas using this method was less than the range found when measuring the psoas muscle directly. An increase of 5 mm from L1&#8211;L4 and 8 mm from L1&#8211;L5 was found when measuring from the TP to the psoas; with a direct measurement, Spivak et. al. found an increase from 15.9 mm at L2&#8211;L3 to 23.3 mm at L3&#8211;L4 and 28.7 mm at L4&#8211;L59. Analysis of the data obtained indicates that the psoas muscle is generally medial to the TP and that aiming laterally would not allow access unless you are at the level of L5. Irrigation and debridement less than 1.5 cm past the transverse process in the sagittal plane should allow for avoidance of the lumbar plexus. However, pathologically, a psoas abscess may expand beyond the normal anatomical margins and a more lateral approach may be possible. MRI is recommended to clearly define the depth and medial to lateral extent of the psoas abscess and a future radiological study would be beneficial to further assess the findings of this method.
Using the measurements found in this study as a guide, one can determine the ability to safely perform irrigation and debridement of a psoas abscess, through a dorsal spinal approach, by staying within the confines of the safe zone at each level and reduce the risk lumbar plexus injury.

A psoas abscess (PA) is a rare diagnosis reported in 0.4&#8211;1 per 10,000 admissions to the hospital1,2. A PA can be caused by hematogenous spread, lymphatic spread from a distant infectious site, or by contiguous spread from adjacent organs3. Currently, percutaneous drainage under real-time computed tomography is a safe and first-line treatment for a PA4. Dietrich et al. found that it has a higher success rate compared to open surgery, offering a lower mortality rate and shorter hospital length of stay2. However, Tabrizian et al. found that 44% of the patients treated with percutaneous drainage underwent open surgery to eradicate the infection5.
Given the rate of open surgeries performed for treatment of psoas abscesses, the aim of the method developed in this study is to find a &#34;safe zone&#34; for irrigation and debridement (I&#38;D) of a psoas abscess via a dorsal approach. An initial ventral approach is taken to identify and isolate key anatomical structures, including the transverse processes (TP), psoas muscle, and lumbar plexus (LP). A dorsal approach is then taken to further isolate the TP and LP from the surrounding structures. Throughout the various steps of dissection, photographs are obtained. Once the dissection is complete, the images are uploaded to ImageJ (1.48v, National Institute of Health) and several measurements are taken to identify the relationship between the TP, LP, and psoas muscle. Finally, using the measurements obtained, a &#34;safe zone&#34; for entering the substance of the psoas and minimizing the risk of lumbar plexus injury is calculated. To our knowledge, this is the first work that uses the transverse processes as reference points for the purpose of finding a safe zone for I&#38;D of a psoas abscess.

<table><tbody><tr><td>Blunt ended dissecting scissors</td><td></td><td></td><td>To cover the specimens</td></tr><tr><td>Camera</td><td>Sony a7 III</td><td>ILCE-7</td><td></td></tr><tr><td>Cobb elevator</td><td>Sklar</td><td>40-6950</td><td>For isolation of TP and general dissection</td></tr><tr><td>Dissection table</td><td></td><td></td><td></td></tr><tr><td>Formalin fixed cadavers</td><td>Restore Life USA</td><td>N/A</td><td>Transected at T12 with abdominal organs removed</td></tr><tr><td>Hemostats</td><td></td><td></td><td></td></tr><tr><td>Retractors</td><td></td><td></td><td>For blunt dissection</td></tr><tr><td>Rongeur</td><td>Sklar</td><td>40-4085</td><td></td></tr><tr><td>Scissors</td><td>Sklar</td><td>15-2555</td><td></td></tr><tr><td>Surgical absorbent pads</td><td></td><td></td><td>Placed under the cadaver to absorb fluids</td></tr><tr><td>Surgical blades/scalpels</td><td>Dynarex</td><td>4110</td><td></td></tr><tr><td>Surgical drape/blanket</td><td></td><td></td><td>For blunt dissection</td></tr><tr><td>Surgical gauze sponges</td><td></td><td></td><td></td></tr><tr><td>Surgical lights</td><td></td><td></td><td></td></tr><tr><td>Surgical Ruler</td><td>Aspen Surgical Products</td><td>42182702</td><td></td></tr><tr><td>Tissue forceps</td><td></td><td></td><td></td></tr><tr><td>Tool tray</td><td></td><td></td><td></td></tr></tbody></table>

posterior approach for debridement of the psoas abscess

This method focuses on outlining a safe zone for irrigation and debridement of a psoas abscess through a posterior approach. Initially, an anterior approach to the spine was performed to ensure that the anterior longitudinal ligament and the psoas muscle could be visualized. All the abdominal organs were removed. Subsequently, a posterior approach was performed to remove the paraspinal muscles from L1&#8211;L5. The transverse processes, pars interarticularis and lamina of L1&#8211;L5 were identified. The exiting nerve root was identified between the transverse processes and followed into the substance of the psoas muscle. Using the anterior and posterior approach, the lumbar plexus was isolated from the substance of the psoas muscle. Before and after various steps of dissection, digital photographs were obtained. These images were uploaded into ImageJ and multiple measurements, including the distance between the lateral superior and inferior tip of each TP to the most lateral region of the plexus, the distance between the lateral superior and inferior tip of the TP to the lateral edge of the psoas, and the width of the lumbar plexus were recorded. The safe zone for entering the substance of the psoas muscle was defined between the lateral edge of the psoas muscle and the lateral edge of the lumbar plexus. The relationship of this interval to the tip of the transverse process at each level was measured and reported.

Eleven formalin-fixed cadavers were included, with an average age of 80.5 years6. Two cadavers had damaged lumbar vertebrae on the right side and were removed. Thus, a total of 20 measurements were included, 13 female and 7 male. The medial border of the safe zone, defined by the most lateral aspect of the lumbar plexus, was found to be approximately 1 cm medial to the tip of the TP at L1&#8211;L3, but narrowed down to approximately 6 and 1 mm at L4 and L5, respectively. The medial border of the safe zone was then subtracted by the distances of the cranial and caudal tip of each TP to the lateral edge of the psoas muscle at each level. This calculation gave us the medial to lateral area of safe debridement. The average area of the safe zone for debridement, at all levels of the lumbar spine, was found to be between 4 and 8 mm.
The area for maximum medial to lateral irrigation and debridement in the coronal plane was determined by measuring the distance from the superior and inferior tips of the TP to the lateral edge of the psoas muscle at the corresponding vertebral level. On average, the maximal extent of lateral debridement one can perform is as follows: 5.5 and 5.7 mm medial to the inferior and superior tips of the TP at L1, 4.7 and 5.1 mm medial at L2, 1.8 and 2.5 mm medial at L3, 0 and 0.4 mm medial at L4, and 3.8 and 3.7 mm lateral at L5. In the sagittal plane, the lumbar plexus was approximately 15&#8211;20 mm anterior to the TP. (Table 1).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/60796/60796fig01.jpg" /> 
Figure 1: Cadaveric image of an anterior approach dissection. The TP, LP and psoas are clearly defined and used as the reference points for measurements. TP = transverse process; LP = lumbar plexus; Ps = lateral edge of psoas; L3, L4, L5 = lumbar vertebrae. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/60796/60796fig1alarge.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="2"></td>
			<td colspan="5">Lumbar Vertebra</td>
		</tr>
		<tr>
			<td colspan="2">Measurement</td>
			<td>L1</td>
			<td>L2</td>
			<td>L3</td>
			<td>L4</td>
			<td>L5</td>
		</tr>
		<tr>
			<td colspan="2">Lateral superior tip of TP to lateral edge of psoas</td>
			<td>-5.7 &#177; 1.92</td>
			<td>-5.11 &#177; 1.84</td>
			<td>-2.52 &#177; 2.63</td>
			<td>-0.42 &#177; 2.39</td>
			<td>3.70 &#177; 1.60</td>
		</tr>
		<tr>
			<td colspan="2">Lateral inferior tip of TP to lateral edge of psoas</td>
			<td>-5.49 &#177; 2.02</td>
			<td>-4.70 &#177; 1.71</td>
			<td>-1.84 &#177; 2.56</td>
			<td>-0.03 &#177; 2.31</td>
			<td>3.77 &#177; 1.57</td>
		</tr>
		<tr>
			<td colspan="2">Lateral superior tip of TP to lateral edge of LP</td>
			<td>-9.3 &#177; 1.94</td>
			<td>-11.75 &#177; 1.59</td>
			<td>-10.47 &#177; 2.90</td>
			<td>-6.64 &#177; 2.53</td>
			<td>-1.01 &#177; 2.31</td>
		</tr>
		<tr>
			<td colspan="2">Lateral inperior tip of TP to lateral edge of LP</td>
			<td>-9.2 &#177; 2.06</td>
			<td>-11.71 &#177; 1.54</td>
			<td>-9.8 &#177; 2.47</td>
			<td>6.24 &#177; 2.43</td>
			<td>-0.89 &#177; 2.40</td>
		</tr>
		<tr>
			<td colspan="2">Lateral edge of LP to lateral edge of psoas calculated using the lateral superior tip of the TP</td>
			<td>3.96 &#177; 0.98</td>
			<td>6.64 &#177; 1.17</td>
			<td>7.94 &#177; 2.00</td>
			<td>6.22 &#177;1.28</td>
			<td>4.71 &#177; 1.38</td>
		</tr>
		<tr>
			<td colspan="2">Lateral edge of LP to lateral edge of psoas calculated using the lateral inferior tip of the TP</td>
			<td>4.03 &#177; 1.05</td>
			<td>7.0 &#177; 1.15</td>
			<td>7.96 &#177; 2.00</td>
			<td>6.21 &#177; 1.77</td>
			<td>4.66 &#177; 1.59</td>
		</tr>
		<tr>
			<td colspan="2">Lateral superior tip of the TP to the LP in the saggital plane</td>
			<td>17.89 &#177; 2.72</td>
			<td>19.08 &#177; 1.93</td>
			<td>19.50 &#177; 3.12</td>
			<td>16.26 &#177; 2.69</td>
			<td>14.97 &#177; 1.90</td>
		</tr>
		<tr>
			<td colspan="2">Lateral inferior tip of the TP to the LP in the saggital plane</td>
			<td>17.84 &#177; 3.03</td>
			<td>18.65 &#177; 1.60</td>
			<td>19.19 &#177; 3.06</td>
			<td>16.27 &#177; 2.93</td>
			<td>14.92 &#177; 1.85</td>
		</tr>
	</tbody>
</table>
Table 1: Mean value in millimeters of 20 sets of measurements, 13 female and 7 male. Negative values indicate that the measurement is medial to the tip of the TP. The distance of the lateral edge of the psoas to the most lateral region of the LP defines the safe zone for medial to lateral debridement. The distance from the tip of the TP to the LP in the sagittal plane defines the safe zone for debridement in the sagittal plane.

Watch this Scientific Journal Video about Posterior Approach for Debridement of the Psoas Abscess at JoVE.com

Posterior Approach for Debridement of the Psoas Abscess

This is a cadaveric study investigating the landmarks for the posterior approach for irrigation and debridement of the psoas abscess. The interval between the transverse processes (TP) was used to access the substance of the psoas muscle.

This method focuses on outlining a safe zone for irrigation and debridement of a psoas abscess through a posterior approach. Initially, an anterior ...

posterior-approach-for-debridement-of-the-psoas-abscess

Universidad San Sebastian

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JoVE Journal

Medicine

10.8K Views.  WellStar Atlanta Medical Center. This is a cadaveric study investigating the landmarks for the posterior approach for irrigation and debridement of the psoas abscess. The interval between the transverse processes (TP) was used to access the substance of the psoas muscle.

Video: Posterior Approach for Debridement of the Psoas Abscess

Ovine Lumbar Intervertebral Disc Degeneration Model Utilizing a Lateral Retroperitoneal Drill Bit Injury

Intervertebral disc degeneration is a significant contributor to the development of back pain and the leading cause of disability worldwide. Numerous animal models of intervertebral disc degeneration have been developed. The ideal animal model should closely mimic the human intervertebral disc with regard to morphology, biomechanical properties and the absence of notochordal cells. The sheep lumbar intervertebral disc model fulfils these criteria. We present an ovine model of intervertebral disc degeneration utilizing a drill bit injury through a lateral retroperitoneal approach. The lateral approach significantly reduces the incision and potential morbidity associated with the traditional anterior approach to the ovine spine. Utilization of a drill-bit method of injury affords the ability to produce a consistent and reproducible injury, of precise dimensions, that initiates a consistent degree of intervertebral disc degeneration. The focal nature of the annular and nucleus pulposus defect more closely mimics the clinical condition of focal intervertebral disc herniation. Sheep recover rapidly following this procedure and are typically mobile and eating within the hour. Intervertebral disc degeneration ensues and sheep undergo necropsy and subsequent analysis at periods from eight weeks. We believe that the drill bit injury model of intervertebral disc degeneration offers advantages over more conventional annular injury models.

Intervertebral disc degeneration is a significant contributor to back pain and a leading cause of disability worldwide. Numerous animal models of intervertebral disc degeneration exist. We demonstrate an ovine model of intervertebral disc degeneration, utilizing a drill bit, which achieves a consistent disc injury and reproducible level of disc degeneration.

Intervertebral disc degeneration is a significant contributor to the development of back pain and the leading cause of disability worldwide. Numerous ...

Three-dimensional Navigation-guided, Prone, Single-position, Lateral Lumbar Interbody Fusion Technique

Lateral interbody fusion provides a significant biomechanical advantage over the traditional transforaminal lumbar interbody fusion due to the large implant size and optimal implant position. However, current methods for lateral interbody cage placement require either a two-staged procedure or a single lateral decubitus position that precludes surgeons from having either full access to the posterior spine for direct decompression or comfortable pedicle screw placement.
Herein is one institution's experience with 10 cases of a prone single-position approach for simultaneous access to the anterior and posterior lumbar spine. This allows both lateral lumbar interbody cage placement, direct posterior decompression, and pedicle screw placement, all in one position. Three-dimensional (3D) navigation is utilized for increased precision in both approaching the lateral spine and interbody cage placement. The traditional blind psoas muscle tubular dilation was also modified. Tubular retractors and lateral vertebral body retractor pins were used to minimize the risks to the lumbar plexus.

The single-position, prone, lateral approach allows for both lateral lumbar interbody placement and direct posterior decompression with pedicle screw placement in one position.

Lateral interbody fusion provides a significant biomechanical advantage over the traditional transforaminal lumbar interbody fusion due to the large ...

Neuroscience

Indocyanine Green-Guided Intraoperative Imaging to Facilitate Video-Assisted Retroperitoneal Debridement for Treating Acute Necrotizing Pancreatitis

Video-assisted retroperitoneal debridement (VARD) is a feasible, minimally invasive necrosectomy method for treating severe acute necrotizing pancreatitis, if it does not resolve or is accompanied with infected necrosis in the retroperitoneum. As there are rarely any visually clear separating surface in white light image between necrotic debris and adjacent inflammatory normal tissues due to extensive retroperitoneal adhesions, VARD is accompanied with the risk of vascular injury, external pancreatico-cutaneous or enterocutaneous fistulae. In view of the above disadvantages, we apply real-time intraoperative near-infrared fluorescence imaging with indocyanine green (ICG) during VARD, which enables visualization of the well-perfused adjacent normal tissues. This modified technique (ICG-guided VARD) can provide a clear separating surface during debridement and reduce the risk of vascular or enteric injury. ICG-guided VARD may facilitate surgeons to perform safer debridement in treating severe acute necrotizing pancreatitis.

This protocol presents Indocyanine Green-guided video-assisted retroperitoneal debridement (ICG-guided VARD) for treating severe acute necrotizing pancreatitis.

Video-assisted retroperitoneal debridement (VARD) is a feasible, minimally invasive necrosectomy method for treating severe acute necrotizing ...

The Transition to an Anterior-Based Muscle Sparing Approach Improves Early Postoperative Function but is Associated with a Learning Curve

Surgeons considering transitioning to an anterior-based approach for THA are concerned about the learning curve and the reported marginal clinical benefit. Accordingly, the first cohort of THAs, which were implanted by a single surgeon using the anterior-based muscle-sparing approach (ABMS), was analyzed. The goal of the study was to test 1) whether patient-reported outcomes improved and 2) whether the complication rate decreased with the number of THAs performed. A retrospective cohort study on the first 30 primary THA cases (27 patients) of one surgeon (January 2021-April 2021) using the ABMS approach was conducted. These 30 THAs were compared to 30 primary THA cases (30 patients) done immediately prior to the transition by the same surgeon (September 2020-December 2020) using the posterior approach (PA). The Oxford Hip Score (OHS), Hip Disability and Osteoarthritis Outcome Score (HOOS Junior), and Forgotten Joint Score (FJS) obtained 6 weeks and 6 months after surgery were compared. In addition, three consecutive groups based on equal numbers of THAs were compared for the incidence of complications and surgery time. At 6 weeks after THA, the OHS was 6 points higher after the ABMS approach (p = 0.0408), and the OHS was comparable at 6 months. The HOOS Junior and FJS were similar at 6 weeks and 6 months after surgery.&#160;In the first 10 THAs using the ABMS approach, one patient had a greater trochanter fracture, and one patient had an intraoperative proximal femur fracture. No further immediate interoperative or postoperative complications occurred. Surgery time significantly reduced with the number of THAs performed. Transitioning from the PA to the ABMS approach is associated with a learning curve, which is limited to the first 20 cases. The effect of improved clinical outcomes is apparent within the early postoperative period. After 6 months, THA patients do well regardless of the approach.

The anterior-based muscle-sparing approach for total hip arthroplasty (THA) is associated with a learning curve. However, the improved clinical outcome in the early post-operative phase makes the consideration to transition worthwhile.

Surgeons considering transitioning to an anterior-based approach for THA are concerned about the learning curve and the reported marginal clinical ...

Advancing LRPS: Optimal Techniques for Challenging Liver Resections

Techniques of Laparoscopic Right Posterior Sectionectomy: Glissonian Approach and a Parenchymal Transection Technique

Laparoscopic liver resections (LLR) have been widely accepted as a treatment option for liver tumors. They offer several advantages over open liver resections, including less blood loss, reduced wound pain, and shorter hospital stays with a comparable oncological outcome. However, laparoscopic resection of lesions in the right posterior section of the liver is challenging due to difficulties in bleeding control and visualizing the surgical field. In the past, laparoscopic right posterior sectionectomy (LRPS) was still in the exploration phase, with undefined risks in the Second International Consensus Conference on LLR in 2014. However, recent technological advancements and increased surgical experience have shown that LRPS can be safe and feasible. It has been found to reduce hospital stay and blood loss compared to open surgery. This manuscript aims to provide a detailed description of the steps involved in LRPS. The key factors contributing to our success in this challenging procedure include proper liver retraction and exposure, the use of an intrahepatic Glissonian approach for inflow control, a technique called the 'ultrasonic scalpel mimic Cavitron ultrasonic surgical aspirator (CUSA)' for parenchymal transection, early identification of the right hepatic vein, and meticulous bleeding control using bipolar diathermy.

Here, we present a protocol to perform laparoscopic right posterior sectionectomy, focusing on two key aspects: the intrahepatic Glissonian approach for inflow control and a parenchymal transection technique using an ultrasonic surgical aspirator.

Laparoscopic liver resections (LLR) have been widely accepted as a treatment option for liver tumors. They offer several advantages over open liver ...

Arthroscopic Double Posteromedial Approach for PCL Cyst Excision

Arthroscopic Excision of Posterior Cruciate Ligament Cysts Using a Double Posteromedial Approach

Cruciate ligament cysts of the knee are a rare condition. Posterior cruciate ligament cysts of the knee are less common than anterior cruciate ligament cysts. In patients with asymptomatic isolated cruciate ligament cysts of the knee, conservative treatment is recommended. Symptomatic cruciate ligament cysts of the knee are mostly manifested as knee hyperflexion pain, straightening pain, knee discomfort after standing for a long time or walking for a long time, etc., which seriously affects the quality of life, surgical treatment can be performed. The surgical treatments can be divided into ultrasound-guided cyst puncture and fluid extraction procedure and arthroscopic cystectomy. Cysts are mostly lobulated with a multi-layer cyst wall, cyst fluid extraction does not remove the cyst wall completely but simply extracts cyst fluid, leading to a high recurrence rate. Arthroscopic surgery can completely remove the cyst wall with little trauma, a low recurrence rate, and fast postoperative recovery, so arthroscopic resection is the most common and preferred method of treatment. Since posterior cruciate ligament cysts mostly occur posterior to the ligament, we remove the cyst wall by adding a double posteromedial approach to the knee joint, and the cyst wall is removed under direct vision, which is simple to operate, the cyst wall is completely cleared, the trauma is small, the postoperative recovery is fast, and there is no recurrence. Here, 8 posterior cruciate ligament cysts were removed with complete postoperative symptom relief, no surgical complications, and no recurrence at 1-year follow-up.

Author Spotlight: Double Posteromedial Approach for Treating Posterior Cruciate Ligament Cysts

We present a surgical approach to treat posterior cruciate ligament cysts by an arthroscopic double posteromedial approach.

Cruciate ligament cysts of the knee are a rare condition. Posterior cruciate ligament cysts of the knee are less common than anterior cruciate ligament ...

Laparoscopic Posterior Radical Antegrade Modular Pancreatosplenectomy for Distal Pancreatic Carcinoma

Distal pancreatic carcinoma is a highly malignant tumor with strong invasiveness, often growing to the edge of the pancreas and penetrating the pancreatic capsule to infiltrate surrounding tissues. In conventional distal pancreatosplenectomy (DPS), tumor cells are prone to spread along the direction of blood and lymphatic reflux due to surgical compression. Additionally, inflammation makes it challenging to achieve R0 resection, leading to a lower patient survival rate. To address these limitations, radical antegrade modular pancreatosplenectomy (RAMPS) was developed, emphasizing deeper excision, including the left anterior renal fascia, the left anterior renal adipose sac, and even the left adrenal gland, to improve the R0 resection rate. With the advancement of minimally invasive surgical techniques, laparoscopic RAMPS (L-RAMPS) is being considered technically safe and feasible in oncology. However, due to technical difficulties and a lack of supporting evidence for clinical application, only a few institutions are currently conducting L-RAMPS. In this context, this article presents detailed techniques for laparoscopic posterior radical antegrade modular pancreatosplenectomy (L-pRAMPS), offering promise for future clinical applications.

Laparoscopic radical antegrade modular pancreatosplenectomy (L-RAMPS) is currently considered technically safe and feasible. However, due to technical challenges and a lack of supporting evidence for widespread clinical applications, only a limited number of institutions are currently conducting L-RAMPS. This article aims to provide detailed techniques for laparoscopic posterior radical antegrade modular pancreatosplenectomy.

Distal pancreatic carcinoma is a highly malignant tumor with strong invasiveness, often growing to the edge of the pancreas and penetrating the pancreatic ...

Laparoscopic Retroperitoneal Treatment of Necrotizing Pancreatitis Complications

Retroperitoneal Laparoscopic Debridement and Drainage for Pancreatic Abscess

In patients with severe necrotizing pancreatitis, pancreatic necrosis and secondary infection of surrounding tissues can quickly spread to the whole retroperitoneal space. Treatment of pancreatic abscess complicating necrotizing pancreatitis is difficult and has a high mortality rate. The well-accepted treatment strategy is early debridement of necrotic tissues, drainage, and postoperative continuous retroperitoneal lavage. However, traditional open surgery has several disadvantages, such as severe trauma, interference with abdominal organs, a high rate of postoperative infection and adhesion, and hardness with repeated debridement. The retroperitoneal laparoscopic approach has the advantages of minimal invasion, a better drainage route, convenient repeated debridement, and avoidance of the spread of retroperitoneal infection to the abdominal cavity. In addition, retroperitoneal drainage leads to fewer drainage tube problems, including miscounting, displacement, or siphon. The debridement and drainage of pancreatic abscess tissue via the retroperitoneal laparoscopic approach plays an increasingly irreplaceable role in improving patient prognosis and saving healthcare resources and costs. The main procedures described here include laying the patient on the right side, raising the lumbar bridge and then arranging the trocar; establishing the pneumoperitoneum and cleaning the pararenal fat tissues; opening the lateral pyramidal fascia and the perirenal fascia outside the peritoneal reflections; opening the anterior renal fascia and entering the anterior pararenal space from the rear; clearing the necrotic tissue and accumulating fluid; and placing drainage tubes and performing postoperative continuous retroperitoneal lavage.

Author Spotlight: Advancements in Retroperitoneal Approach for Necrotizing Pancreatitis

To improve the drainage of patients with necrotizing pancreatitis complicated with peripancreatic abscess and reduce the mortality of patients with necrotizing pancreatitis, we adopted a retroperitoneal approach for peripancreatic abscess debridement and drainage by laparoscopy.

In patients with severe necrotizing pancreatitis, pancreatic necrosis and secondary infection of surrounding tissues can quickly spread to the whole ...

A Retrospective Study on Endoscopic Surgery for the Treatment of Paravertebral Abscess in Spinal Tuberculosis Patients

Spinal tuberculosis (TB) remains a significant global health concern, necessitating the development of innovative treatment strategies. This clinical study aimed to evaluate the efficacy and safety of endoscopic debridement as a minimally invasive approach for treating paravertebral abscesses in patients with spinal tuberculosis. A total of 52 patients diagnosed with paravertebral tuberculosis abscesses were enrolled in this retrospective study. Patients were assigned to two groups: the endoscopic debridement group (n = 30) and the conventional open surgery group (n = 22), based on the type of surgery they received. Clinical outcomes were assessed at baseline, post-treatment, and follow-up visits at regular intervals, including surgery time, intraoperative blood loss, total hospital stay duration, pain relief, and neurological improvement. The results of this study demonstrate that endoscopic debridement is a highly effective treatment for paravertebral abscesses in patients with spinal TB. Patients in the endoscopic debridement group experienced significant improvements in surgery time, intraoperative blood loss, total hospital stay duration, pain relief, and neurological improvement compared to those in the conventional open surgery group. Additionally, the endoscopic approach resulted in fewer complications, such as wound infections and postoperative instability, with no cases of recurrence observed during the follow-up period. Therefore, this clinical study highlights the potential of endoscopic debridement as a safe and effective treatment modality for spinal tuberculosis. The technique not only effectively eliminates infected tissue but also ensures faster patient recovery and reduces postoperative complications. Additional research and long-term follow-up studies are necessary to confirm the long-term effectiveness and safety of endoscopic debridement as the standard treatment for spinal tuberculosis.

This study evaluated endoscopic debridement for treating paravertebral abscesses in patients with spinal tuberculosis. Compared to conventional surgery, it significantly improved surgery time, blood loss, hospital stay, pain relief, and neurological outcomes, with fewer complications and no recurrences. These findings highlight its efficacy and safety. Further long-term studies are recommended.

Spinal tuberculosis (TB) remains a significant global health concern, necessitating the development of innovative treatment strategies. This clinical ...

Surgical Approach and Complications of Stand-alone Lateral Trans-Psoas Interbody Fusion

Interbody fusion of the lumbar spine is a standard procedure for symptomatic degenerative lumbar spine disease if conservative treatment fails. Surgical decompression and fusion of the segment can be achieved using several different techniques. Over the last decades, minimally invasive techniques, such as lateral interbody fusion (LLIF), have been developed to reduce tissue damage and complications and allow quicker patient recovery. With growing popularity, indications for LLIF have expanded to treat spinal deformities and foraminal/central stenosis. Mechanically, it allows for an unsurpassed fixation through the left-to-right apophyseal ring placement of the cage. LLIF utilizes a minimally disruptive retroperitoneal corridor and includes both trans-psoas and pre-psoas approaches. For the pre-psoas approach, the risk of damage from manipulation of the intramuscular lumbar plexus is reduced compared to a trans-psoas approach. However, increased risks of major vascular, ureteral, bowel injury and sympathetic plexus damage are reported.
This article aims to provide a detailed and comprehensive guide on stand-alone lateral trans-psoas interbody fusion, including its indications, surgical procedure, potential complications, and outcomes based on a decade of experience from a single center.

Interbody fusion of the lumbar spine can be achieved surgically using different techniques. Minimally invasive techniques, including lateral interbody fusion, have been developed within recent decades to reduce rates of complications and allow for quicker patient recovery. We provide insight into stand-alone lateral trans-psoas interbody fusion, highlighting potential complications and pitfalls.

Interbody fusion of the lumbar spine is a standard procedure for symptomatic degenerative lumbar spine disease if conservative treatment fails. Surgical ...