Fascia

After being transferred into a spatial database, CT images were processed using Analytic Morphomics, a semi-automated image analysis method that has been previously described^{23 ,36} . A combination of automated and user-guided algorithms written in Matlab (The Mathworks Inc, Natick, MA) identified the vertebral bodies to serve as an anatomical coordinate reference system. Next, the outer abdominal fascia and inner muscle wall were identified at all available vertebral levels to create enclosed regions of interest, which were confirmed by multiple trained researchers (Fig. 3).Figure 3

Example of healthy 20 y/o male T10-L5 axial CT slices showing SMA (blue-shaded area) between outer abdominal fascia (yellow line) and inner muscle wall (red line).

Sample size at each vertebral level varied due to differences in anatomy included in each scan. Measurements at T8 and T9 were excluded due to statistically significant differences in mean weight compared to those at T10 through L5. For T10-L5, there there were no significant differences in mean age, weight, or height within the male and female cohorts.
SMA was measured at the axial slice nearest the inferior aspect of each vertebral body as the area of pixels within −29 to +150 Hounsfield Units (HU) as previously validated^{21 (link),23 ,27} . Skeletal muscle index (SMI)–a heuristic that normalizes muscle area for height–was computed as SMA divided by height-squared³⁷ . Skeletal muscle radiation attenuation (SMRA) was computed as the mean Hounsfield Unit (HU) value of all pixels included in SMA^{27 ,38 (link),39 (link)}.

Sepsis was induced following a modification of a previously published method of CLP [10 (link)]. Briefly, animals were anesthetized with intraperitoneal injection of ketamine and xylazine (250 and 10 mg/kg, respectively). After adequate anesthesia, the lower quadrants of the abdomen were shaved and the surgical area was disinfected. A longitudinal midline incision was made using a scalpel, and scissors were used to extend the incision into the peritoneal cavity. After intramuscular, fascial, and peritoneal incision, the cecum was located and exteriorized. In our experiments, the cecum was ligated at different lengths below the ileocecal valve to avoid bowel obstruction. Total cecal length was measured from the tip of the ascending cecum to the tip of the descending cecum. The cecum was then ligated at 5, 20, and 100 % of its total length. For the “100 %” group, the cecum was ligated to the longest possible without bowel occlusion (Fig. 1).Fig. 1

Description of cecal length ligation methods. The total length of the cecum is represented by the full line. Dotted arrows are placed at each level of cecal ligation: 5, 20, and 100 % of the total of cecum length

The cecum was then perforated by a single puncture midway between the ligation and the tip of the cecum with a 20-G needle. We chose this needle diameter to obtain mid-grade lethal sepsis [5 (link), 13 (link), 14 (link)]. After removing the needle, a small amount of feces was extruded. The cecum was relocated, after which the fascia, abdominal musculature, and peritoneum were closed via simple running sutures; the skin was also sutured. The control mice were anesthetized and underwent laparotomy without puncture or cecal ligation and served as the control. The animals were shocked or control-operated and euthanized at different times depending on the set of experiments.
Immediately post-procedure, 1 ml of saline was administered subcutaneously for fluid resuscitation (circa 0.045 ml/g) [8 (link), 14 (link)]. Pain control for CLP and sham mice was achieved with 0.05 mg/kg buprenorphine every 12 h.

A tongue-shaped flap was created on the radial wall of the 5th digit, with the longitudinal edges not exceeding the radial surface of the digit, and the distal edge made slightly beyond the PIP joint line. To ensure full coverage of the volar skin defect, the flap was made 2 mm larger in diameter than the recipient site (Fig. 2).Figure 2

Representative illustrations of camptodactyly of the 5th digit. (a) Frontal and lateral views of the 5th digit before surgery. (b) Design of the tongue-shaped flap, with the longitudinal edges limited within the radial surface, and the distal edge made slightly exceeding the proximal interphalangeal joint line. (c) The volar incision. (d) The lateral view of the digit flap transfer, with direct suturing performed for closure of the donor site. (e) The volar view of the digit after flap transfer, with complete coverage of the volar skin defect.

While creating the edges of the flap, care was taken to preserve the perforating blood vessels of the proper palmar digital arteries, as well as the proper palmar digital nerves.
Sequential release of affected soft tissues was performed in the following order—skin, subcutaneous fibrous fascia, flexor digitorum superficialis tendon, lumbrical muscle insertions if present, and volar plate. The degree of passive extension of the PIP joint was repeatedly tested, and surgical release was considered complete upon achieving full passive extension of the joint. Kirschner (K)-wire fixation was performed following volar plate release.
The radial flap was rotated 90° to cover the volar skin defect, and direct suturing was performed to close the donor site. Free skin grafting was indicated in the presence of high suture tension.
Mupirocin ointment and petroleum jelly (Vaseline) were subsequently applied, and the wound was wrapped with clean dressing. All digits were immobilized in the extended position with a cast for three weeks.

For the PTED group, the surgical procedure (based on the L4–L5 segment of DLS) was performed following methods reported in the literature [18 (link)]. The following steps were performed: (1) part of the superior articular process (SAP) of L5 was removed. A soft pillow was placed under the patients' waist, while the patient was in the lateral decubitus position with their knee and hip flexed. The incision was located 8–12 cm from the midline horizontally and 1–3 cm above the iliac on the side with leg pain. The mixed local anesthetic, which consisted of 30 mL 1:200,000 epinephrine and 20 mL 2% lidocaine, was only used in PTED group. After 5 mL of the mixed anesthetic was inserted into the skin at the entry point, 20 mL was inserted into the trajectory, 15 mL was inserted into the articular process, and 10 mL was inserted into the foramen. Then, 0.8–1.0 cm of skin and the subcutaneous fascia were incised. Drills were used to resect the ventral osteophytes on the SAP. The PTED system (Hoogland Spine Products, Germany) was inserted (Fig. 1). (2) Parts of the ipsilateral ligamentum flavum, perineural scar, and extruded lumbar disc material were completely resected with endoscopic forceps (Fig. 2). (3) The superior endplate of the L5 vertebral body was removed by endoscopic micro punches and a bone knife. Therefore, 270-degree decompression of the traversing nerve root was achieved (Fig. 3). The drainage tube was placed after hemostasis was reached.Fig. 1

Fluoroscopic views. A, B The drill was inserted to resect the LF and the ventral osteophytes on the SAP. C, D The working cannula was placed

Fig. 2

Endoscopic views. A Endoscopic view of the hypertrophic posterior longitudinal ligament, extruded disc material, and perineural scar. B–G After the endoscopic instruments were used to carefully remove the vertebral body, ventral decompression of the traversing nerve root (L5) was completed. H The dura mater was torn

Fig. 3

Illustrations of the 270-degree PTED. A, B Specific pathologic features of LRS-DLS. C, D Final view of the nerve 270-degree decompression status and the restoration of the lateral recess

For the MIS-TLIF group, the surgical procedure was performed in accordance with methods reported in the literature [19 (link)]. After successful general anesthesia with tracheal intubation, the patient was placed in a prone position with chest and hip pads, and the L4–L5 intervertebral space was marked with X-ray fluoroscopy. The skin and subcutaneous fascia were cut; a trans-muscular surgical corridor was created with two micro-laminectomy retractors docking on the facet joint complex. After exposing the bony structure, part of the lamina and inferior articular process of L4 and the upper L5 articular process were removed with the rongeur on the ipsilateral side, and the hypertrophic ligamentum flavum was peeled backward. If MRI showed contralateral lateral recess stenosis, then predecompression was performed on the contralateral side. After decompression on the dorsal side, the nucleus pulposus and endplate cartilage were removed with forceps. An appropriate cage (Medtronic) filled with autograft from laminectomy was placed in the center of the intervertebral space via the Kambin’s triangle area. After adequate hemostasis was achieved, two drainage tubes were placed and removed when the drainage volume was < 50 mL/d.
Postoperatively, patients was treated with oral nonsteroidal anti-inflammatory drugs and antibiotics for 3 days. All patients were encouraged to perform straight leg raising 1 day postoperatively, and moderate off-bed activity with a brace 2–3 days postoperatively. On the third postoperative day, patients were allowed to go home if their lower extremity pain symptoms were effectively relieved with no evidence of infection. The patient demographics and perioperative outcomes were compared. The VAS score, ODI, and modified Macnab criteria were used to evaluate the clinical outcomes [20 (link)].