Study DesignRetrospective.PurposeTo analyze whether the cross-sectional area of the intervertebral foramen at the outermost edge of the resection site is associated with postoperative outcomes and whether our fluoroscopic method for determining the resection area is appropriate.Overview of LiteratureThere is no consensus on the criteria for determining an optimal resection area to obtain sufficient decompression while maintaining intervertebral stability in posterior percutaneous endoscopic cervical foraminotomy. Previous reports have recommended a facet resection rate (FRR) of ≤50%. Intervertebral foramen stenosis often extends to the exit zone. The cross-sectional area of the intervertebral foramen is occasionally small at the outermost edge of the resection site. No report has analyzed whether these aspects are associated with postoperative outcomes.MethodsLateral margins of the resection area were set at lateral borders of the vertebral body on frontal fluoroscopic view. Because the percutaneous endoscope has a small diameter, surrounding structures can easily be identified using frontal view fluoroscopy to determine the resection area. FRRs were calculated from postoperative computed tomography images. The smallest cross-sectional area of the intervertebral foramen around the lateral edge of the resection area (SALE) was measured and compared wit clinical outcomes.ResultsThe mean FRR was 41.7% at C5–C6 and 48.9% at C6–C7. SALE was not correlated with clinical outcomes.ConclusionsResidual stenosis in the lateral portion of the intervertebral foramen is weakly associated with postoperative outcomes. Our process achieved adequate FRRs and favorable postoperative outcomes, suggesting that our criteria for determining the resection area are appropriate.

Study DesignRetrospective clinical study.PurposeThis study investigated the relationship between surgical approaches and surgical outcomes in patients undergoing percutaneous endoscopic cervical discectomy (PECD), including the reduction in intervertebral disc height and the incidence of Modic changes.Overview of LiteratureThe anterior approach involves partial invasion of the intervertebral disc, with a reported reduction in intervertebral disc height after PECD.MethodsForty-two patients with cervical disk hernia who underwent PECD and magnetic resonance imaging at least 3 months postoperatively were divided into four groups according to the hernia sites and the surgical approach used: unilateral hernia treated using the contralateral approach (group C, n=18), unilateral hernia treated using the ipsilateral approach (group I, n=15), midline hernia (group M, n=4), and broad and bilateral hernia (group B, n=5). Modic changes and intervertebral disc height were evaluated.ResultsThe overall incidence of Modic changes was 52.4%: 72.2% in group C, 26.7% in group I, 25.0% in group M, and 80.0% in group B. The reduction in intervertebral disc height was 21.8% across all the patients: 24.5% in group C, 11.0% in group I, 22.8% in group M, and 23.9% in group B.ConclusionsThe incidence of Modic changes and the reduction in intervertebral disc height were lower in the patients treated using the ipsilateral approach than in those treated using the contralateral approach. Traditionally, a contralateral approach has been used for PECD; however, the ipsilateral approach is more appropriate and is therefore recommended.

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Introduction Although lumbar interbody fusion is effective for low back pain caused by severe disk degeneration, it is a highly invasive procedure. Less invasive procedures such as transforaminal lumbar interbody fusion (TLIF) and lumbar lateral interbody fusion have become available; however, there is still scope for improvement. We performed full percutaneous endoscopic lumbar interbody fusion (PELIF), a technique designed as a safe and less invasive percutaneous fusion. Method and Subjects Our technique is indicated for patients with chronic low back pain in whom conservative treatment was not effective, thinning of the intervertebral disk was prominent, and temporary pain relief was achieved with a disk block. In the operation, percutaneous endoscopic diskectomy was performed with a 7.5-mm sheath inserted through a small incision, and a cage was inserted percutaneously using an L-shaped retractor. Instead of pedicle screw fixation, hybrid facet screw fixation was performed. Low back pain was improved, and bone union was confirmed on radiography. This technique was used in six patients, and no surgery-related complications occurred. Discussion The L-shaped retractor used in this series can protect the exiting nerve by inserting it into the sheath, then removing the sheath and placing the rounded corner of the retractor on the lateral cranial side. This technique is safe with no other associated risks. Cages larger than the sheath can be inserted, and commercially available cages for TLIF are applicable. Hybrid facet screw fixation can overcome the problems associated with both conventional transfacet pedicle screw fixation and translaminar facet screw fixation by combining these two procedures. Conclusion PELIF is an easy, safe, and fully percutaneous technique with very low invasiveness that uses an L-shaped retractor and hybrid facet screw fixation. This procedure can be a treatment option for patients with severe low back pain related to disk degeneration.

Background Spinal epidural hematoma (SEH) frequently occurs after microendoscopic decompressive laminotomy (MEDL), and a drain may not be functioning sufficiently. Objective To reduce the incidence of SEH after MEDL. Methods  A urokinase-treated antithrombogenic drain, which is available only with a large diameter, was reduced in diameter and used after MEDL. Magnetic resonance imaging (MRI) and computed tomography (CT) were performed 36 to 48 hours after surgery. The size of the SEH was measured by MRI, and the location of the drain tip was assessed by CT scan. After imaging, the drain was removed. Results Use of the urokinase-treated antithrombogenic drain reduced the incidence of SEH. However, the drain was not adequately placed in many cases, limiting the effect of the drainage. When the urokinase-treated antithrombogenic drain was placed contralaterally to the approach side using an unsheathed endoscope, the incidence of SEH was further reduced. Conclusions The urokinase-treated antithrombogenic drain prevented thrombus-related drain obstruction. In addition, unsheathed endoscopic contralateral placement of the drain was effective for SEH prevention.