The Arthrospine Duo (GESCO Healthcare Pvt. Ltd., Chennai, India) system comprises of a conical tube, a single inflow cannula sheath which is compatible with 0° or 30° 4-mm arthroscope, a set of 5-mm and 10-mm cannulated dilators and a pair of working top inserts air (A-1), saline (S-2) with a provision of tightening screw to anchor the sheath-scope construct to the top insert (Figure 1).

After administration of spinal or general anesthesia, the patient is placed in prone position over bolsters and the back of the patient is cleaned and draped. The symptomatic lumbar level to be approached is confirmed using lateral fluoroscopy by inserting an 18-gauge spinal needle into the paraspinal musculature approximately one finger-breadth (1.5 cm) lateral to the midline. The needle is directed laterally towards the facet (to avoid inadvertent dural puncture) and repositioned until it is directly in line with the disc space in lateral view. The spinal needle is then withdrawn and a 10–15 mm long skin and fascial incision is made at the puncture site. Through the incision, a 5-mm dilator is transmuscularly inserted towards the spinolaminar junction under tactile control, followed by passage of a second 10-mm cannulated dilator with special beveled type tip over the first dilator. The retraction of muscles and fibromuscular tissue from spinolamina junction, interlaminar window up to facet is achieved by the sweeping movements of 10-mm dilator in craniocaudal and mediolateral direction. However, care must be exercised to prevent advancing the initial dilator into the spinal canal. The Arthrospine conical tube is introduced over the dilator over the symptomatic level then both dilators are withdrawn. Arthrospine working channel air (A-1) is then snugly fit over the Arthrospine tube by simple press-fit way. The arthroscope is locked in the sheath and is connected to the endoscopic camera under sterile conditions. Scope with sheath and suction tube are introduced into their respective ports. At this stage, the correct placement of the Arthrospine tube is checked under image intensifier guidance, to prevent wrong level entry in both anteroposterior and lateral views. For central and paracentral disc herniations, an interlaminar approach is utilized. For extraforaminal or far lateral disc prolapse, tube docking is done lateral to isthmus/pars. Under endoscopic visualization, fibromuscular tissue bulging in the mouth of the tube is shrunk with microbipolar coagulation (dry mode) or radiofrequency probe (saline view), this is further aided by the removal of soft tissue by pituitary rongeur. Cottonoids can also be placed over the lamina to push away the fibro-muscular tissue and clear the lamina. Once boundaries of the interlaminar window such as superior and inferior lamina, facet joint, and spinolaminar junction are clearly visualized, the surgeon can remove the entire tube assembly from the operative wound area.

The surgeon connects a saline tubing to the scope-sheath construct and can turn on the saline flow. Now the saline will flow from the tip of the scope-sheath construct under gravity aided flow. The surgeon can now directly insert the scope, held by the left hand (for a right-handed surgeon), into the surgical wound; and the routine instruments like burr, radiofrequency device, penfield, Kerrison punch, disc rongeurs can be inserted via right dominant hand through the same surgical incision. This converts the system into a free-hand saline endoscopy through a single incision.

The initial bone work is started with a 2- or 3-mm Kerrison punch or arthroscopic 4-mm burr at spinolamina junction thus detaching flavum from under surface of upper lamina. Further bony decompression, flavum excision and partial medial facet removal can be done under free-hand control under saline medium. Any significant disc hernia can be removed after adequate recess decompression and gentle retraction of the nerve root. The saline usually flows freely out of the surgical wound reducing risk of increasing saline pressure. If there is any concern for improper saline exit, a semitubular retractor can be placed inside and held by assistant to maintain a proper saline outflow.

At the end of the procedure, hemostasis is achieved by radiofrequency coagulation. We usually place a small hemovac drain in case of patients who are on blood thinners, have osteopenic bone quality and who had excessive epidural bleeding during procedure. The lumbar fascia is sutured using vicryl 2-0 suture followed by the closure of the skin in a subcuticular fashion followed by water impermeable dressing. Patients are mobilized the same day once effect of anesthesia wears off.

Destandau Endospine [1,2] and EasyGo [3] are dry media based spine endoscopy. Stenoscope based full endoscopy [4], PSLD, UBE, BESS work in saline media. The Arthrospine technique [5-7] can be used in both dry and saline medium.

This technique allows usage of conventional spine instruments as are utilized in biportal endoscopy through a single incision port. The initial soft tissue clearance is eased by use of initial dilators and Arthrospine tube which reduces the time required to clear the interlaminar window in comparison with other saline based endoscopy techniques.

Fixed system microtubular surgeons who wish to graduate to saline endoscopy techniques can utilize their fixed tube to facilitate initial tube docking and clearing of lamina and interlaminar window under microscopic assistance and then remove the tube and insert the saline endoscope as a free-hand method to ease their transition of clearing soft tissues, simplifying triangulation/ orientation difficulty in initial learning period.

We believe that use of conventional spine instruments through a single incision in free-hand saline medium endoscopy also would help spine surgeons control healthcare costs especially in developing countries where full-endoscopy systems can have significant financial implications.

Conversion to free-hand saline endoscopy via Arthrospine technique is a simple and effective way to achieve the mobility of the biportal technique, allows usage of conventional spine instruments for standard discectomy and decompression via a single incision approach and can help a fixed tubular or dry medium surgeon to ease transition to a saline endoscopy medium and save on healthcare costs.