Funding was provided by the Zhejiang Medical and Health Science and Technology project (project numbers: 2021433841 and 2023564481).

Ethical approval was obtained from the Medical Ethics Committee of the authors&#39; hospital. Informed consent was obtained from each patient.
1. Inclusion/exclusion criteria and preoperative preparation
<ol>
	<li>Include patients with the following preoperative symptoms: unable to walk steadily, numbness of the lower limbs, atrophy of the lower limbs, leg weakness, uncontrolled movement of the lower extremities, or sphincter dysfunction, etc., as well as signs and imaging d...

<ol>
	<li>Miura, K., 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=Thoracic+myelopathy+caused+by+calcification+of+the+ligamentum+flavum.">Thoracic myelopathy caused by calcification of the ligamentum flavum.</a> Journal of Rural Medicine. 15 (2), 65-67 (2020).</li><li>Wang, T., Yin, C., Wang, D., Li, S., Chen, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+technique+for+decompression+of+severe+thoracic+myelopathy+due+to+tuberous+ossification+of+ligamentum+flavum.">Surgical technique for decompression of severe thoracic myelopathy due to tuberous ossification of ligamentum flavum.</a> Clinical Spine Surgery. 30 (1), 7-12 (2017).</li><li>Baba, S., 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=Microendoscopic+posterior+decompression+for+the+treatment+of+thoracic+myelopathy+caused+by+ossification+of+the+ligamentum+flavum:+A+technical+report.">Microendoscopic posterior decompression for the treatment of thoracic myelopathy caused by ossification of the ligamentum flavum: A technical report.</a> European Spine Journal. 25 (6), 1912-1919 (2016).</li><li>Ahn, D. K., 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=Ossification+of+the+ligamentum+flavum.">Ossification of the ligamentum flavum.</a> Asian Spine Journal. 8 (1), 89-96 (2014).</li><li>Isaacs, R. E., 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=Minimally+invasive+microendoscopy-assisted+transforaminal+lumbar+interbody+fusion+with+instrumentation.">Minimally invasive microendoscopy-assisted transforaminal lumbar interbody fusion with instrumentation.</a> Journal of Neurosurgery. Spine. 3 (2), 98-105 (2005).</li><li>Li, K. K., Chung, O. M., Chang, Y. P., So, Y. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelopathy+caused+by+ossification+of+ligamentum+flavum.">Myelopathy caused by ossification of ligamentum flavum.</a> Spine. 27, 308-312 (2002).</li><li>Okada, K., 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=Thoracic+myelopathy+caused+by+ossification+of+the+ligamentum+flavum.+Clinicopathologic+study+and+surgical+treatment.">Thoracic myelopathy caused by ossification of the ligamentum flavum. Clinicopathologic study and surgical treatment.</a> Spine. 16 (3), 280-287 (1991).</li><li>Ikuta, K., 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=Decompression+procedure+using+a+microendoscopic+technique+for+thoracic+myelopathy+caused+by+ossification+of+the+ligamentum+flavum.">Decompression procedure using a microendoscopic technique for thoracic myelopathy caused by ossification of the ligamentum flavum.</a> Minimally Invasive Neurosurgery. 54 (5-6), 271-273 (2011).</li><li>Osman, N. S., 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=Outcomes+and+complications+following+laminectomy+alone+for+thoracic+myelopathy+due+to+ossified+ligamentum+flavum:+A+systematic+review+and+meta-analysis.">Outcomes and complications following laminectomy alone for thoracic myelopathy due to ossified ligamentum flavum: A systematic review and meta-analysis.</a> Spine. 43 (14), 842-848 (2018).</li><li>Hou, X., 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=A+systematic+review+of+complications+in+thoracic+spine+surgery+for+ossification+of+ligamentum+flavum.">A systematic review of complications in thoracic spine surgery for ossification of ligamentum flavum.</a> Spinal Cord. 56 (4), 301-307 (2018).</li><li>Hu, X., Ohnmeiss, D. D., Lieberman, I. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+an+ultrasonic+osteotome+device+in+spine+surgery:+experience+from+the+first+128+patients.">Use of an ultrasonic osteotome device in spine surgery: experience from the first 128 patients.</a> European Spine Journal. 22 (12), 2845-2849 (2013).</li><li>Florence, J. M., 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=Intrarater+reliability+of+manual+muscle+test+(Medical+Research+Council+scale)+grades+in+Duchenne's+muscular+dystrophy.">Intrarater reliability of manual muscle test (Medical Research Council scale) grades in Duchenne's muscular dystrophy.</a> Physical Therapy. 72 (2), 115 (1992).</li><li>Kumar, S. P., Ramasubramanian, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Babinski+sign--A+reappraisal.">The Babinski sign--A reappraisal.</a> Neurology India. 48 (4), 314-318 (2000).</li><li>Liu, 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=Analysis+of+the+surgical+strategy+and+postoperative+clinical+effect+of+thoracic+ossification+of+ligament+flavum+with+dural+ossification.">Analysis of the surgical strategy and postoperative clinical effect of thoracic ossification of ligament flavum with dural ossification.</a> Frontiers in Surgery. 9, 1036253 (2022).</li><li>Li, X., 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=Surgical+results+and+prognostic+factors+following+percutaneous+full+endoscopic+posterior+decompression+for+thoracic+myelopathy+caused+by+ossification+of+the+ligamentum+flavum.">Surgical results and prognostic factors following percutaneous full endoscopic posterior decompression for thoracic myelopathy caused by ossification of the ligamentum flavum.</a> Scientific Reports. 10, 1305 (2020).</li><li>Hosono, N., 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=Potential+risk+of+thermal+damage+to+cervical+nerve+roots+by+a+high-speed+drill.">Potential risk of thermal damage to cervical nerve roots by a high-speed drill.</a> The Journal of Bone and Joint Surgery. British Volume. 91 (11), 1541-1544 (2009).</li><li>Hara, M., Takayasu, M., Takagi, T., Yoshida, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=En+bloc+laminoplasty+performed+with+threadwire+saw.">En bloc laminoplasty performed with threadwire saw.</a> Neurosurgery. 48 (1), 235-239 (2001).</li><li>Vercellotti, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technological+characteristics+and+clinical+indications+of+piezoelectric+bone+surgery.">Technological characteristics and clinical indications of piezoelectric bone surgery.</a> Minerva Stomatologica. 53 (5), 207-214 (2004).</li><li>Nickele, C., Hanna, A., Baskaya, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteotomy+for+laminoplasty+without+soft+tissue+penetration,+performed+using+a+harmonic+bone+scalpel:+Instrumentation+and+technique.">Osteotomy for laminoplasty without soft tissue penetration, performed using a harmonic bone scalpel: Instrumentation and technique.</a> Journal of Neurological Surgery. Part A, Central European Neurosurgery. 74 (3), 183-186 (2013).</li><li>Sanborn, M. R., 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=Safety+and+efficacy+of+a+novel+ultrasonic+osteotome+device+in+an+ovine+model.">Safety and efficacy of a novel ultrasonic osteotome device in an ovine model.</a> Journal of Clinical Neuroscience. 18 (11), 1528-1533 (2011).</li><li>Schaeren, S., 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=Assessment+of+nerve+damage+using+a+novel+ultrasonic+device+for+bone+cutting.">Assessment of nerve damage using a novel ultrasonic device for bone cutting.</a> Journal of Oral and Maxillofacial Surgery. 66 (3), 593-596 (2008).</li><li>St&#252;binger, S., Kuttenberger, J., Filippi, A., Sader, R., Zeilhofer, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoral+piezosurgery:+Preliminary+results+of+a+new+technique.">Intraoral piezosurgery: Preliminary results of a new technique.</a> Journal of Oral and Maxillofacial Surgery. 63 (9), 1283-1287 (2005).</li><li>Vercellotti, T., Pollack, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+bone+surgery+device:+Sinus+grafting+and+periodontal+surgery.">A new bone surgery device: Sinus grafting and periodontal surgery.</a> Compendium of Continuing Education in Dentistry. 27 (5), 319-325 (2006).</li></ol>

Laminectomy is the conventional treatment method for thoracic ossified ligamentum flavum. However, the improper use of traditional bone-cutting equipment, such as high-speed drills and revolving burrs, can result in nerve thermal injury, grasping the soft tissue, tearing the dura mater, and mechanical injury15,16,17. An ultrasonic osteotome is a novel bone-cutting tool used for precise osteotomies. This device allows for bone di...

Thoracic ossification of the ligamentum flavum (TOLF) is one of the major causes of thoracic spinal stenosis and has been established as the primary cause of thoracic myelopathy1,2,3. TOLF is characterized by the replacement of the ligamentum flavum by ectopic new bone formation. The incidence of TOLF is as high as 36% in Japan and 63.9% in China. Most patients show slow progression to symptomatic thoracic canal stenosis or thoracic myelopathy4. Decompression is the only effective treatment for TOLF once it becomes symptomatic since conservative treatment is usually ineffective5.
Laminoplasty, laminectomy, and lamina fenestration are three surgical techniques that have been demonstrated to be effective for TOLF6,7,8. However, the surgical outcomes are not always satisfactory. The conventional methods can result in a high rate of perioperative complications such as dural laceration and/or iatrogenic spinal cord injury9,10. Therefore, it is important to develop a more efficient and secure surgical technique for TOLF.
Here, we describe in detail a method for laminectomy of the thoracic spine using an ultrasonic osteotome combined with a conventional osteotome to resect the lamina (Figure 1). An ultrasonic osteotome is a precision tool that uses ultrasonic oscillations in its blade to selectively cut mineralized tissue, preventing collateral tissue damage11. The technique presented herein is a relatively safe and easy-to-learn method that should be recommended for the treatment of TOLF.
An ultrasonic osteotomy system is designed to cut hard bone structures effectively while preserving soft tissues by converting the electrical input signal into vertically mechanical oscillations at an amplitude of 0-120 &#181;m and a frequency of 39 kHz. The system consists of a power unit, a handpiece, several tips, and a footswitch. An irrigation pump is also integrated into the system, and this delivers saline to the cutting edge to reduce local thermal necrosis.
Presented here is a case of 57 year old male patient who presented with lower limb weakness with unsteady walking for 3 years. The symptoms were more pronounced on the right side. Physical examination revealed that the patient&#39;s muscle strength grade12 was 5 (barely detectable weakness) for both the lower limbs. Additionally, numbness of the skin occurred when acupuncture was applied below the left inguinal plane, hypoesthesia was observed when needling the skin in the saddle area, the deep tendon reflexes were slightly increased in both lower limbs, and the Babinski sign13 was positive. X-ray, CT, and MRI showed thoracic ossification of the ligamentum flavum at T10-11. The preoperative data are presented in Figure 2.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>C-arm X-ray machine</td>
			<td>GE&#160;</td>
			<td>20192060063</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Cera styptica</td>
			<td>Johnson&#38;Johnson (China) Medical Equipment Co., Ltd</td>
			<td>W810T</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Conventional osteotome</td>
			<td>Suzhou qingniu medical instrument co.</td>
			<td>10012.01</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Cottonoids</td>
			<td>Piaoan Holding Group Co., Ltd</td>
			<td>20182640073</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Fluid gelatin</td>
			<td>Johnson&#38;Johnson (China) Medical Equipment Co., Ltd</td>
			<td>20183142459</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Gelatin sponge</td>
			<td>B.Braun Melsungen AG&#160;</td>
			<td>20163642299</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Jackson&#8211;Pratt drainage</td>
			<td>Suzhou Weikang Medical Equipment Co., Ltd</td>
			<td>20162140955</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Kerrison Rongeurs</td>
			<td>Jinzhong Medical Instruments Co., Ltd</td>
			<td>2100888</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Nerve dissector</td>
			<td>Jinzhong Medical Instruments Co., Ltd</td>
			<td>p23110</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Pedicle screw</td>
			<td>Medtronic</td>
			<td>76446545</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Towel clamps</td>
			<td>KEWEIDUN</td>
			<td>10058468134417&#160;&#160;&#160;</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Ultrasonic Osteotomy Surgical System</td>
			<td>SMTP Technology Co.</td>
			<td>FD880A</td>
			<td>/</td>
		</tr>
		<tr>
			<td>Unipolar/bipolar electrotome</td>
			<td>Shanghai Hutong Electronics Co., Ltd&#160;</td>
			<td>20143251899</td>
			<td>/</td>
		</tr>
	</tbody>
</table>

laminectomy for the removal of thoracic ossification of the ligamentum flavum (tolf) using ultrasonic and conventional osteotomes

Thoracic ossification of the ligamentum flavum (TOLF) is a common cause of progressive thoracic myelopathy. TOLF is typically treated with surgical decompression. A variety of surgical techniques, including laminoplasty, laminectomy, and lamina fenestration, are used for the effective treatment of TOLF. However, traditional methods are associated with a substantial risk of perioperative complications, including dural laceration and/or iatrogenic spinal cord injury. Therefore, it is important to develop an efficient and secure surgical technique for TOLF. Herein, we describe a method for laminectomyperformed at the thoracic spine using an ultrasonic osteotome combined with a conventional osteotome. This technique can reduce intraoperative complications. This is a relatively safe and easy-to-learn method that should be recommended for the treatment of TOLF.

Representative case results 
On the first postoperative day, the CT scans revealed that the ossification had been fully removed, and the spinal cord had been completely decompressed (Figure 5). The patient could walk steadily. The muscle strength of both lower limbs was 5. The patient was discharged 3 days after the operation.
A total of 71 patients were enrolled in the study. All surgeries were carried out satisfactorily. The mean duration o...

Watch this Scientific Journal Video about Laminectomy for the Removal of Thoracic Ossification of the Ligamentum Flavum TOLF Using Ultrasonic and Conventional Osteotomes at JoVE.com

Laminectomy for the Removal of Thoracic Ossification of the Ligamentum Flavum TOLF Using Ultrasonic and Conventional Osteotomes

We present a methodology for using an ultrasonic osteotome combined with a conventional osteotome for laminectomy in thoracic ossification of the ligamentum flavum. This is a relatively safe and easy-to-learn method that avoids the perioperative complications associated with the conventional method.

Laminectomy for the Removal of Thoracic Ossification of the Ligamentum Flavum (TOLF) Using Ultrasonic and Conventional Osteotomes

Thoracic ossification of the ligamentum flavum (TOLF) is a common cause of progressive thoracic myelopathy. TOLF is typically treated with surgical ...

In this video we'll share a case using laminectomy for the removal of thoracic ossification of the ligamentum flavum using ultrasonic and conventional osteotome. Thoracic ossification of the ligamentum flavum is a well-known cause of thoracic spinal stenosis that has been identified as a primary cause of thoracic myelopathy. The conservative treatment is generally ineffective, so once the TOLF is symptomatic, decompression is almost the only effective method.Several types of surgical methods has been shown to be effective for TOLF including laminoplasty, laminectomy, and lamina fenestration. There's a high rate of perioperative complications, such as dural laceration and/or iatrogenic spinal cord injury. Here, we report in detail a method for laminectomy in thoracic spine using ultrasonic osteotome combined with conventional osteotome to resect the lamina, which is effective and safer for the treatment of TOLF.Ethical approval was obtained from the Medical Ethics Committee of the author's hospital, and informed the consent was obtained from each patient. Here is a brief history of the patient. And we find ossification of the ligamentum flavum between T10 and 11.Under general anesthesia, the patient was placed in prone position. Neurophysiological monitoring involving SSEPs and MEPs was conducted throughout the surgery. The TOLF levels were identified with a C-arm before operation.Surgery area was disinfected using PVP-I, and draped with sterile surgical towels. They involved the levels of TOLF were identified intra-operatively via a C-arm X-ray machine. A longitudinal midline incision was made over the spinous process extending from the spinous process above to the spinous process below the level of pathology.The posterior bony structure including the spinous processes, bilateral lamina, and zygapophyseal joints of the involved levels were exposed using unipolar electrotome. The pedicle screw entry points were determined based on anatomical landmarks according to the AO method, which is the intersection between the midlines of the facet joint and transverse process. Pedicle marker pins were inserted to mark the pedicle screw entry points, and also used as a reference for the lateral border of the thoracic spinal cord.The spinous processes, along with the supraspinous and interspinous ligaments were then removed using a bone rongeur from the cranial to the caudal end of the decompression zone. Usually a part of the spinous process was maintained to help removing the lamina. The incision was irrigated with saline to identify bleeding sites, a sterilized medical cera sryptica was used for hemostasis on the residual supraspinous.A rectangular decompression zone was identified as a area between the midpoints of the facet joints bilaterally and between the inferior portions of the superior lamina and superior portions of the inferior lamina of the TOLF involved segments. The ultrasonic osteotome was used to cut the lamina horizontally on cranial and the caudal ends of the decompression zone. And longitudinally between the midpoints of the facet joints bilaterally.The cutting can be performed for multiple times until your feeling the lamina is cutting through. The conventional osteotome was used to lever the lamina upwards in turn from side to side. The bounce sound of the bone indicates the lamina has been completely cut off.After lamina was loosened, one or two towel clamps were used to clamp the root of the spinous process, and the entire lamina is elevated carefully. When there is adhesion between the ossified tissue and the dura matter, a nerve dissector can be used for this attachment. The remaining articular process and the edge of the lamina on both sides were further detected and trimmed using Kerrison Rongeur to ensure fully decompression.After thoroughly hemostasis with bipolar electrocoagulation and cera styptica, the dural surface was covered with gelatin sponge or fluid gelatin, and cottonoids. Then, the pedicle marker pins were replaced by pedicle screws. In some cases, the bone fragments from the vertebral lamina were minced and implanted bilaterally between the transverse processes.Titanium rods were connected and screw nuts were tightened. Throughout the operation, hemostasis were achieved using bipolar electrocoagulation and cera styptica. Jackson-Pratt drainage was routinely performed for 24 to 48 hours in patient without the dura tears.Dehydration management and neurotrophic medications were administered after the operation. Intravenous methylprednisone was administrated for three days. Patients were instructed to perform rehabilitation exercise to help functional recovery.The muscle strength was improved remarkably and the patient was discharged three days after operation. On the first postoperative day CD scans revealed that the ossification has been fully removed and the spinal cord has been completely decompressed. For the whole 71 patients, no catastrophic complications, such as major vascular injury, spinal cord injury, or pleural effusion formation occurred during surgery.The CT result on the first postoperative day confirmed that the ossification was completely resected and that spinal cord decompression was sufficient. The bone structure can be selectively removed without damaging the adjacent nerve tissue, due to the precise oscillations of the ultrasonic blade. Combined with careful removal of the lamina with the use of osteotome and towel clamps mentioned above, the low operation time, low blood loss, low complication rate was achieved.In conclusion, based on the result of the current study, ultrasonic osteotome combined with conventional osteotome to resect the lamina for laminectomy has been shown as an effective, safe, and feasible option for the treatment of thoracic ossification of the ligamentum flavum.

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2.4K visualizações.  Zhejiang University. Neste vídeo vamos compartilhar um caso usando laminectomia para a remoção da ossificação torácica do ligamento flavo usando osteotomo ultra-sônico e convencional. A ossificação torácica do ligamento flavo é uma causa bem conhecida de estenose espinhal torácica que tem sido identificada como uma causa primária de mielopatia torácica. O tratamento conservador é geralmente ineficaz, portanto, uma vez que o TOLF é sintomático, a descompressão é quase o único método eficaz.