Background and Objectives: Spinal minimally invasive surgery (MIS) experts at the university hospital worked as a team to develop a new treatment algorithm for pyogenic spondylodiscitis in lumbar and thoracic spines. They modified a flow chart introduced for this condition in a pre-MIS era to incorporate MIS techniques based on their extensive experiences accumulated over the years, both in MIS for degenerative lumbar diseases and in the treatment of spine infections. The MIS procedures incorporated in this algorithm consisted of percutaneous pedicle screw (PPS)–rod fixation and transpsoas lateral lumbar interbody fusion (LLIF). The current study analyzed a series of 34 patients treated with prospective selection of the methods according to this new algorithm. Materials and Methods: The algorithm first divided the patients into those who had escaped complicated disease conditions, such as neurologic impairment, extensive bone destruction, and the need to be mobilized without delay (Group 1) (19), and those with complicated pyogenic spondylodiscitis (Group 2) (15). Group 1 had image-guided needle biopsy followed by conservative treatment alone with antibiotics and a spinal brace (12) (Group 1-A) or a subsequent addition of non-fused PPS–rod fixation (7) (Group 1-B). Group 2 underwent an immediate single-stage MIS with non-fused PPS–rod fixation followed by posterior exposure for decompression and debridement through a small midline incision (12) (Group 2-A) or an additional LLIF procedure after an interval of 3 weeks (3) (Group 2-B). Results: All patients, except four, who either died from causes unrelated to the spondylodiscitis (2) or became lost to follow up (2), were cured of infection with normalized CRP at an average follow up of 606 days (105–1522 days). A solid interbody fusion occurred at the affected vertebrae in 15 patients (50%). Of the patients in Group 2, all but two regained a nearly normal function. Despite concerns about non-fused PPS–rod instrumentation, only seven patients (21%) required implant removal or replacement. Conclusions: Non-fused PPS–rod placements into infection-free vertebrae alone or in combination with posterior debridement through a small incision worked effectively in providing local stabilization without contamination of the metal implant from the infected tissue. MIS LLIF allowed for direct access to the infected focus for bone grafting in cases of extensive vertebral body destruction.

OBJECTIVE: The efficacy of anterior column realignment (ACR) remains relatively unclear, possibly because some safety concerns have limited its adoption and extensive evaluation. The authors aimed to study whether a minimally invasive surgery (MIS) triad consisting of ACR, lateral lumbar interbody fusion, and percutaneous pedicle screw fixation in a select group of adult spinal deformity (ASD) patients helps shorten fusion length without compromising clinical and radiographic outcomes over a minimum 2-year follow-up period. METHODS: A series of 61 ASD patients (mean age 72.8 years) with pelvic incidence (PI) − lumbar lordosis (LL) (PI-LL) mismatch > 10° underwent the short-segment MIS triad (mean fusion length 3.0 levels) as a single-stage operation with a mean operative time and estimated blood loss of 157 minutes and 127 mL, respectively. Exclusion criteria were 1) thoracic scoliosis as the main deformity, 2) thoracolumbar junction kyphosis > 25°, 3) ankylosed facet joints, and 4) previous spinal fusion surgery. Seven patients, who needed fusion to be extended to S1, underwent mini-open transforaminal lumbar interbody fusion at L5–S1. RESULTS: The segmental disc angle at the ACR level more than quintupled, averaging from 2.9° preoperatively to 18.9° at the latest follow-up (p < 0.0001). LL, in turn, nearly doubled from 17.0° to 32.8° (p < 0.0001) and PI-LL decreased by nearly half from 28.8° to 13.2° (p < 0.0001). At the same time, other spinopelvic deformity parameters as well as Oswestry Disability Index (ODI) scores significantly improved. Patients were divided into two groups at the latest postoperative evaluation: 36 patients whose PI-LL improved to < 10° and 25 patients who maintained a PI-LL mismatch > 10°. Binary logistic regression revealed preoperative PI-LL mismatch as the only factor that significantly influenced this dichotomous separation postoperatively. Receiver operating characteristic curve analysis identified the critical preoperative mismatch of 26.4° with 68% sensitivity and 84% specificity. Despite this different radiographic consequence, the two groups had an equally successful clinical outcome with no significant difference in ODI scores. CONCLUSIONS: As long as the ASD characteristics are consistent with the authors’ exclusion criteria, the short-segment MIS triad served as an excellent surgical option in the patients with preoperative PI-LL mismatch < 26.4°, but the technique also worked well even in those with a mismatch > 26.4°, although ideal spinopelvic alignment targets were not necessarily achieved in these patients.

OBJECTIVE: The anterior column realignment (ACR) procedure, which consists of sectioning the anterior longitudinal ligament/annulus and placing a hyperlordotic interbody cage, has emerged as a minimally invasive surgery (MIS) for achieving aggressive segmental lordosis enhancement to address adult spinal deformity (ASD). Although accumulated evidence has revealed indirect neural decompression after lateral lumbar interbody fusion (LLIF), whether ACR serves equally well for neural decompression remains to be proven. The current study intended to clarify this ambiguous issue. METHODS: A series of 36 ASD patients with spinopelvic mismatch, defined as pelvic incidence (PI) minus lumbar lordosis (LL) > 10°, underwent a combination of ACR, LLIF, and percutaneous pedicle screw (PPS) fixation. This “MIS triad” procedure was applied over short segments with mean fusion length of 3.3 levels, and most patients underwent single-level ACR. The authors analyzed full-length standing radiographs, CT and MRI scans, and Oswestry Disability Index (ODI) scores in patients with minimum 1 year of follow-up (mean [range] 20.3 [12–39] months). RESULTS: Compared with the preoperative values, the radiographic and MRI measurements of the latest postoperative studies changed as follows. Segmental disc angle more than quadrupled at the ACR level and LL nearly doubled. MRI examinations at the ACR level revealed a significant (p < 0.0001) increase in the area of the dural sac that was accompanied by significant (p < 0.0001) decreases in area and thickness of the ligamentum flavum and in thickness of the disc bulge. The corresponding CT scans demonstrated significant (all p < 0.0001) increases in disc height to 280% of the preoperative value at the anterior edge, 224% at the middle edge, and 209% at the posterior edge, as well as in pedicle-to-pedicle distance to 122%. Mean ODI significantly (p < 0.0001) decreased from 46.3 to 26.0. CONCLUSIONS: The CT-based data showing vertebral column lengthening across the entire ACR segment with an increasingly greater degree anteriorly suggest that the corrective action of ACR relies on a lever mechanism, with the intact facet joints acting as the fulcrum. Whole-segment spine lengthening at the ACR level reduced the disc bulge anteriorly and the ligamentum flavum posteriorly, with eventual enlargement of the dural sac. ACR plays an important role in not only LL restoration but also stenotic spinal canal enlargement for ASD surgery.

This retrospective study aimed to evaluate the clinical outcomes of circumferential minimally invasive surgery (CMIS) using lateral lumbar interbody fusion (LLIF) and percutaneous pedicle screw (PPS) in adult spinal deformity (ASD) patients, and to clarify the conditions for achieving postoperative pelvic incidence-lumbar lordosis (PI-LL) < 10°. Demographics and other parameters of ASD patients who underwent CMIS and who were divided into groups G (achieved postoperative PI-LL < 10°) and P (PI-LL ≥ 10°) were compared. Of the 145 included ASD patients who underwent CMIS, the average fused level, bleeding volume, operative time, and number of intervertebral discs that underwent LLIF were 10.3 ± 0.5 segments, 723 ± 375 mL, 366 ± 70 min, and 4.0 segments, respectively. The rod material was titanium alloy in all the cases. The PI-LL significantly improved from 37.3 ± 17.9° to 1.2 ± 12.2° postoperatively. Pre- and postoperative PI, postoperative LL, preoperative PI-LL, PI-LL after LLIF, and postoperative PI-LL were significantly larger in group P. PI-LL after LLIF was identified as a significant risk factor of postoperative PI-LL < 10° by logistic regression, and the cut-off value on receiver operating characteristic curve analysis was 20°. Sufficient correction was achieved by CMIS. If PI-LL after LLIF was ≤20°, it was corrected to the ideal alignment by the PPS procedure.

OBJECTIVE: Acute/subacute osteoporotic vertebral collapses (OVCs) in the lower lumbar spine with neurological compromise, although far less well documented than those in the thoracolumbar junction, may often pose greater treatment challenges. The authors clarified the utility of 3 familiar combined techniques of minimally invasive surgery for this condition as an alternative to the corpectomy/expandable cage strategy. METHODS: This report included the authors’ first 5 patients with more than 2 years (range 27–48 months) of follow-up. The patients were between 68 and 91 years of age, and had subacute painful L4 OVC with neurological compromise and preexisting lumbar spinal stenosis. The authors’ single-stage minimally invasive surgery combination consisted of the following: step 1, balloon kyphoplasty for the L4 OVC to restore its strength, followed by L4–percutaneous pedicle screw (PPS) placement with patients in the prone position; step 2, tubular lateral lumbar interbody fusion (LLIF) at the adjacent disc space involved with endplate injury, with patients in the lateral position; and step 3, supplemental PPS–rod fixation with patients in the prone position. RESULTS: Estimated blood loss ranged from 20 to 72 mL. Neither balloon kyphoplasty–related nor LLIF-related potentially serious complications occurred. With CT measurements at the 9 LLIF levels, the postoperative increases averaged 3.5 mm in disc height and 3.7 mm in bilateral foraminal heights, which decreased by only 0.2 mm and 0 mm at the latest evaluation despite their low bone mineral densities, with a T-score of −3.8 to −2.6 SD. Canal compromise by fracture retropulsion decreased from 33% to 23% on average. As indicated by MRI measurements, the dural sac progressively enlarged and the ligamentum flavum increasingly shrank over time postoperatively, consistent with functional improvements assessed by the physician-based, patient-centered measures. CONCLUSIONS: The advantages of this method over the corpectomy/expandable cage strategy include the following: 1) better anterior column stability with a segmentally placed cage, which reduces stress concentration at the cage footplate-endplate interface as an important benefit for patients with low bone mineral density; 2) indirect decompression through ligamentotaxis caused by whole-segment spine lengthening with LLIF, pushing back both the retropulsed fragments and the disc bulge anteriorly and unbuckling the ligamentum flavum to diminish its volume posteriorly; and 3) eliminating the need for segmental vessel management and easily bleeding direct decompressions. The authors’ recent procedural modification eliminated step 3 by performing loose PPS–rod connections in step 1 and their tight locking after LLIF in step 2, reducing to only once the number of times the patient was repositioned.

Study Design. A prospective analysis. Objective. To test if threshold-based monitoring of compound muscle action potentials (CMAPs) by stimulating the screw loaded to uninsulated extender sleeve provides a valid safety warning for percutaneous pedicle screw (PPS) placements in the lumbosacral spine. Summary of Background Data. Utility of the CMAP monitoring to PPS procedures remains controversial. Methods. A series of 202 patients underwent a total of 1664 lumbosacral PPS placements under CMAP monitoring without fluoroscopic guidance. The monitoring consisted of stimulating the PPS assembled to uninsulated extender sleeve and recording CMAPs from the vastus medialis, biceps femoris, tibialis anterior, and medial gastrocnemius. Automated steps of a threshold hunting algorithm using 0.2-ms duration pulses of increasing intensities delivered at 2/s allowed quick determination of a minimum stimulation current to evoke >100-μV amplitude CMAPs. Results. At L2 through S1 spines, postoperative CT scans identified 51 medial or inferior pedicle wall breaches of 1536 screws (3.3%) without neurologic complications. The ROC curve analysis determined the critical cut-off threshold value of 27 mA (74% sensitivity and 95% specificity) for predicting 35 breaches of 627 screws (5.6%) at L2 and L3, and of 17 mA (100% sensitivity, 98% specificity) for 16 of 909 (1.8%) at L4 through S1. While advancing the screw, 3 breaches (5.9%) showed a particularly low threshold of ≤6-mA, allowing the surgeon to immediately redirect the screw and retest the new trajectory as safe. Conclusion. Screw stimulation with threshold hunting algorithm has a distinct advantage over the time-consuming insulated pilot hole stimulation, allowing an uninterrupted flow of the surgery. The present findings have documented practical usefulness and reliability of CMAP monitoring using direct stimulation of the PPS assembled to uninsulated extender sleeve. Level of Evidence: 2