YESS Foraminoscopic System - Specified by Anthony Yeung, M.D. Produced by Richard Wolf
In 1997, the YESSS (Yeung Endoscopic Spine System) ,produced by Richard Wolf, has been introduced into the market. The specification has been worked out by Anthony Yeung, MD, a spine surgeon with decades of experience in the treatment of herniated discs. The system is produced and distributed by the German Endoscopy Manufacturer Richard Wolf.
By competent description of the operation technique and device through Anthony Yeung at al., but also marketing activities of Richard Wolf, the YESS – System still is accepted world wide by numerous spine surgeons.
The basis for the development and application of Foraminoscopes are experiences in the field of percutaneous discectomy by its development stages. Early Foraminoscopes were specified and produced by H.J. Leu / Karl Storz and Hal Matthews / Danek Inc. 1991 . Their use has been described in several publications.
Method and Material
The concept of Yeung Endoscopic Spine Surgery (YESS) uses the “inside-out” technique, first safely accessing the disc, then selectively removing disc tissue from the base of the herniation and pulling the extruded nucleus back within the disc and out via the cannula. Then the cannula can be manipulated to access the epidural space, lateral facets and foramen and inspect the traversing and exiting nerve roots. The initial needle trajectory and placement is crucial because it will ultimately determine the endoscopic field of view. (Original text of Anthony Yeung, M.D.)
Data of YESS Foraminoscope (Brochure Richard Wolf, Medical Corp. Vernon 1999)
Working length: 210 mm
Working Channel: 2.7 mm
Rod lens Optical System: Diameter of the rod lens 2.9 mm
Direction of view 30°
Dual irrigation channels
Fiber light illumination (Cold light source)
Use of 30° (20°) direction of view
Great variation of surgical instruments to serve a wide range of applications
Special slotted and bevel-ended operation cannulas allowed viewing of the intradiscal space, fragmentectomy and laser foraminoplasty
The working channel diameter of the 1997 Foraminoscope allowed only the use of instruments and devices of 2.5 mm diameter under endoscopic visualization, which is half of instruments diameter used for percutaneous nucleotomy. Dimensions of Richard Wolf Foraminoscopes changed about 2004