Minimally invasive percutaneous endoscopic discectomy (PED) with a transforaminal approach under local anesthesia was started in the late 20th century. As the procedure requires a skin incision of only 8 mm, it is the least invasive disc surgery procedure at present, and owing to advances in instruments and optics, the use of this technique has gradually spread. In Japan, Dr. Dezawa from Teikyo University Mizonokuchi Hospital introduced this technique in 2003. Thanks to his efforts, the number of surgeons who can perform PED has increased, although the number of active PED surgeons is still only around 20. The first author (K.S.) started PED in 2010. In this review article, we explain the state-of-the-art PED transforaminal technique for minimally invasive disc surgery and present three successful cases.

: The minimally invasive percutaneous endoscopic discectomy (PED) as the postero-lateral approach with the local anesthesia was started in the late 20th century. The procedure only requires 8 mm of skin incision ; thus, it is the least invasive disc surgery presently. The surgery related complications were reviewed in the initial 100 cases from the single surgeon (K.S., first author). Two cases showed exiting nerve irritation, and complained of leg paresthetic pain for 6 to 12 weeks after the surgery (2.0% %). The symptoms got better with medicines. One showed post-surgical epidural hematoma, and required surgical removal of the mass (1.0% %). Two cases complained neck pain during surgery (2.0% %). Surgeons would be aware of the specific complications for the postero-lateral approach of PED procedure. J. Med. Invest. 61 : 264-269, August, 2014

: The pedicle screw (PS) system is widely used for spinal reconstruction. Recently, screw insertion using the cortical bone trajectory (CBT) technique has been reported to provide increased holding strength of the vertebra, even in an osteoporotic spine. CBT is also beneficial due to its low invasiveness. We have been performing hybrid reconstruction with CBT at the cranial level and PS at the caudal level based on the concept of minimal invasiveness. We applied this hybrid technique to 6 cases of degenerative spondylolisthesis. Surgery was completed with a small skin incision of around 5-6 cm, which is shorter than that of the conventional PS procedure. The mean percent slippage before surgery was 19.8% %, and this was reduced to 3.9% % after surgery and almost maintained 3 months after surgery. Furthermore, no major surgical complications were observed. Here, we introduce the minimally invasive hybrid technique of CBT-PS. Surgeons should be aware of the procedure as an option for minimally invasive lumbar spine reconstructive surgery.

Connective tissues such as tendon, ligament and cartilage are mostly composed of extracellular matrix (ECM). These tissues are insoluble, mainly due to the highly cross-linked ECM proteins such as collagens. Difficulties obtaining suitable samples for mass spectrometric analysis render the application of modern proteomic technologies difficult. Complete solubilization of them would not only elucidate protein composition of normal tissues but also reveal pathophysiology of pathological tissues. Here we report complete solubilization of human Achilles tendon and yellow ligament, which is achieved by chemical digestion combined with successive protease treatment including elastase. The digestion mixture was subjected to liquid chromatography-mass spectrometry. The low specificity of elastase was overcome by accurate mass analysis achieved using FT-ICR-MS. In addition to the detailed proteome of both tissues, we also quantitatively determine the major protein composition of samples, by measuring peak area of some characteristic peptides detected in tissue samples and in purified proteins. As a result, differences between human Achilles tendon and yellow ligament were elucidated at molecular level.

Percutaneous endoscopic discectomy (PED) is a minimally invasive disc surgery that can be performed under local anesthesia and requires only an 8-mm skin incision. For transligamentous extruded nucleus pulposus with foraminal stenosis, it is very hard to remove the migrated mass with a simple transforaminal approach. For such difficult cases, foraminoplasty and an epiduroscopic technique is useful. A 29-year-old man visited the authors’ hospital, complaining of low-back and right leg pain. MRI revealed a massive herniated nucleus pulposus with foraminal stenosis. A transforaminal PED was planned to remove the herniated mass. Through the inside-out technique, the base of the herniated mass was removed. Following the foraminoplasty, the cannula was moved into the epidural space. With epidural observation just beneath the nerve root, the extruded transligamentous fragment was confirmed and removed en bloc. Immediately after the surgery, the patient’s symptoms resolved. The combination of foraminoplasty and epiduroscopic observation during the transforaminal approach for PED is a useful and reliable technique to remove extruded transligamentous disc fragments.

Lumbar spondylolysis in elementary school age children was commonly a terminal-stage bone defect at L5, which was not necessarily related to history of athletic activity and was sometimes asymptomatic. It was often associated with SBO, indicating a possible congenital predisposition. These findings may provide further insight into the pathogenesis of lumbar spondylolysis.

MRI revealed a higher prevalence of L3 or L4 spondylolysis than observed with CT.

Various complications after microendoscopic discectomy (MED) are well known, but postoperative discal cyst is a unique and relatively unknown complication. Here, we report on two teenage patients who presented with postoperative discal cyst after MED for herniated nucleus pulposus (HNP), which resolved after conservative treatment. The patients were diagnosed with HNP at L4-5 and L5-S1 based on MRI and then treated by MED. Postoperative discal cyst was diagnosed on MRI after recurrence of symptoms. Both patients were managed conservatively. T2-weighted MRI demonstrated hyperintense collections adjacent to the operated intervertebral disc level, which were communicating with the corresponding disc annulus. Because the clinical symptoms were relatively mild, the patients were managed conservatively; both made a complete clinical recovery with radiological evidence of improvement. Postoperative discal cyst is a relatively unknown complication after MED for HNP. Surgeons should be aware of this postoperative complication when operating on young individuals with HNP.