Background: The differences in clinical and radiographic outcomes between 3-dimensional computer navigation (NAV) and fluoroscopic-guided (FLUO) minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) are currently unclear, with different studies showing different advantages of each technique. This study aimed to compare the clinical and radiographic outcomes of NAV and FLUO MIS-TLIF. Furthermore, we determined the correlation between radiographic findings and predictable clinical outcomes.Methods: Between January 2016 and October 2018, 97 consecutive patients who had undergone MIS-TLIF with the lumbosacral degenerative disease in our institute were retrospectively reviewed. Radiographic outcomes (angle of screw convergence, screw-to-pedicle diameter ratio, %screw depth, screw penetration, %fusion, and facet joint violation) were analyzed by 2 independent orthopedists using thin-slice computed tomography. Clinical outcomes were assessed with Oswestry Disability Index (ODI), visual analog scale (VAS), and satisfaction score. The association between radiographic and clinical outcomes was then analyzed to determine the predictable variable outcomes.Results: Sixty-one patients (270 screws) in the FLUO group and 36 patients (172 screws) in the NAV group were compared. The NAV group showed a significantly higher %screw depth (89.04% ± 6.07% vs 85.18% ± 7.54%; P = 0.011), larger angle of screw convergence (27.7° ± 3.93° vs 18.44° ± 7.54°; P < 0.001), lower incidence of pedicle penetration (0% vs 3.7%; P = 0.016), and less facet joint violation (1.0% vs 8.1%; P = 0.003). The clinical results revealed a significantly better VAS and ODI in the NAV group at 6 and 12 months. The %screw depth correlated with the VAS back pain score at the 1-year follow-up.Conclusions: NAV MIS-TLIF showed superior screw placement accuracy, better screw convergence and depth, and lower cranial facet joint violation than FLUO MIS-TLIF. Furthermore, better clinical scores were revealed in the NAV group at the 6-month and 1-year follow-up.Level of Evidence: 3.

BACKGROUNDThis study aimed to describe the least invasive surgical technique of endoscopic decompression for thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) and to review the literature available on the diagnosis and treatment of OLF.OBSERVATIONSThe mean age of the patients was 51.2 (range, 40–62) years, and the mean preoperative, 2-week postoperative, and last follow-up modified Japanese Orthopaedic Association scores were 6.6 (range, 4–10), 9.6 (range, 7–11), and 13 (range, 10–14), respectively. All patients were discharged within 48 hours after the surgery. The mean follow-up period was 13.2 (range, 7–18) months. No complication was found perioperatively, and none of the patients had postoperative instability during the follow-up period.LESSONSBased on this clinical case series and literature review, the authors conclude that endoscopic decompression surgery is feasible and effective for managing thoracic myelopathy caused by OLF while minimizing surrounding tissue damage. Additionally, it enables shorter periods of hospital stay.

Study Design: Anatomic cadaver study. Objective: Translaminar facet screw fixation supplements unilateral pedicle screw-rod fixation in minimally invasive transforaminal lumbar interbody fusion (TLIF). Various screw diameters, lengths, trajectories, and insertion points are used; however, they do not represent true screw trajectory. We aimed to evaluate lumbar laminar anatomy and suggest a safe and effective insertion point and trajectory during lumbar-translaminar facet screw fixation in an anatomic cadaver study. Methods: O-arm navigation simulating the true translaminar facet screw trajectory was used to evaluate L1-S1 in cadaveric spines. The inner and outer diameters, length, and trajectory of the screw pathway were measured along the trajectory from the spinous process base through the contralateral lamina, crossing the facet joint to the transverse process base using 2 starting points: cephalad one-third (1/3SL) and one-half (1/2SL) of the spinolaminar junction. Results: Using the 1/2SL starting point, the outer and inner lamina diameters did not differ significantly from L1-L5 (7.47 ± 1.38 to 6.7 ± 1.84 mm and 4.73 ± 1.04 to 3.86 ± 1.46 mm, respectively). Screw length (36.16 ± 4.02 to 49.29 ± 10.07 mm) and lateral angle increased (50.28° ± 8.78° to 60.77° ± 8.88°), but caudal angle decreased (16.19° ± 9.01° to 1.13° ± 11.31°). Lamina diameter and screw length did not differ with different starting points. L2-L3 caudal angles were lower in the 1/2SL starting point. Conclusion: A 36- to 50-mm translaminar facet screw—with 5.0-mm diameter for L1-L2 and 4.5-mm diameter for L3-L5—can be inserted at the middle of the spinolamina, especially during minimally invasive TLIF, with a 50° to 60° lateral angle relative to the spinous process, and a caudal angle of 16° to 1° relative to the spinolamina from L1-L5.

Objective: First, to propose a novel minimally invasive technique of full-endoscopic anterior odontoid fixation (FEAOF) that aims to reduce the risk of retropharyngeal approach (both open and percutaneous techniques) to anterior odontoid screw fixation. Second, to describe steps of the procedure and, lastly, to report the initial outcomes in patients treated with this novel technique.Methods: Four non-consecutive patients who were diagnosed with a displaced odontoid fracture (Anderson-D'Alonzo classification type II and Grauer subclassification type A or B) from 2019 to 2020 underwent surgical fixation by our novel technique for anterior odontoid screw fixation. A detailed technical approach of FEAOF for the surgical treatment of type II odontoid fractures was described, and the patients' outcomes based on postoperative radiographic results including computed tomography (CT), clinical outcome parameters including visual analogue scale (VAS) for neck pain both preoperatively and at postoperative follow-up, and range of neck motion at the final follow-up were reported. Results:The mean age was 33.5 years (24-41), three patients were male. The mean operative time was 93.75 min, and the mean blood loss was 7.5 ml. An immediate post-operative thin-sliced CT showed that all patients achieved satisfactory reduction and proper screw position. No screw malposition or penetration was found. At a 6-month follow-up, a thin-sliced CT demonstrated solid bony union in every case. The mean VAS for neck pain was reduced from 6.5 to 0.6 at the 6-months follow-up. At the final follow-up, all patients showed improvement in ranges of motion without any complications; however, one patient was lost to follow-up.Conclusions: FEAOF is a feasible and effective option for treating type II odontoid fractures. The procedure is less invasive than other techniques and provides clear direct visualization of the involved structures.

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Background: Odontoid fractures are common among cervical spine fractures and are categorized into three types. Unstable type II fractures are among the most challenging to treat, and the best treatment approach has been debated. Anterior odontoid screw fixation, a surgical treatment option, yields a high union rate and helps preserve cervical motion; however, there are risks for approach-related complications. Here, we report a novel minimally invasive technique of full-endoscopic anterior odontoid fixation (FEAOF).Methods: The authors introduce the technique and describe in detail the technical approach of FEAOF for the surgical treatment of type II odontoid fractures.Conclusions: FEAOF is a feasible and effective option for treating type II odontoid fractures. The procedure is less invasive than other techniques and provides clear direct visualization of the involved structures.Level of Evidence: Not applicable