The variety of procedures in spinal surgery is extensive. While anterior and posterior open approaches are the conventional approaches, it is the posterior approach that is most frequently used. Traditionally, the open posterior exposure involves a central midline incision and sub-periosteal exposure of the posterior elements by elevation of the paraspinal muscles with a Bovie. The exposure of spotless and bloodless chalky-white bone is a matter of pride for a senior professor to demonstrate and a matter of delightful pursuit for a budding spinal fellow. A well-functioning Bovie, Cobb’s elevators and self-retaining retractors form the foundation for a gratifying exposure, writes Arvind Kulkarni.
While this kind of open exposure is still the most widely utilised practice across the world, there are certain drawbacks to this approach. Irrespective of the pathology most spinal lesions in need of attention are focal manifestations (eg. disc herniations, spinal stenosis, and spondylodiscitis). An elaborate exposure just to get access to the spinal canal and treat these focal lesions seems unnecessary. The incisions are long, the dissection is extensive and the morbidity increases proportionally with the body mass index of the patient, and the extent of surgery. Moreover, the healing is not anatomical with scarring of the paraspinal muscles and creation of a large dead space at the site of surgery. A conventional destructive laminectomy adds to the morbidity and results in short-term and long-term sequalae and complications contributing to failed back. There is significant radiological as well as biochemical literature to support the hypothesis that open approaches add to considerable paraspinal muscle damage.
The tubular retractor has revolutionised and changed the perspective of spinal surgery. It allows us to treat focal compressive and unstable lesions without disturbing the normal anatomy. Although the initial development of tubular surgery—and its most common indication—revolved around lumbar disc herniations, the versatility of the technique has now been widely realised. It allows the surgeon to treat a plethora of spinal conditions that are seen in clinical practice. The properties of the tubular retractor can be exploited well to deal with the most difficult of conditions.
Multilevel pathologies can be treated with small incisions and ports causing minimal morbidity to the patients. With increasing experience, surgeons can deal with cervical and thoracic lesions, too. In unstable conditions, single and multilevel interbody fusions can be performed using small ports augmented by percutaneous pedicle screws and rods, thereby avoiding extensive dissections and morbidity to the patients. Anterior minimal access techniques using tubular retractors are becoming increasingly popular, and will eventually replace wide extensive anterior exposures that are generally associated with considerable physical morbidity and poor cosmesis. The stand-point of tubular retractors with reference to management of complications, value-based spinal care and obese patients, etc., makes it an attractive and efficient tool. Our experience (to be published in Asian Spine Journal shortly) suggests that the postoperative surgical site infection rate in tubular surgeries is several folds less when compared with the statistics of historical controls of open spine surgeries; in fact, in the study, the infection rate in non-instrumented tubular surgeries was found to be 0%. This accomplishment has several obvious social and financial healthcare implications.
Again, a study conducted by our team on the management of cerebrospinal fluid leaks in minimal access tubular surgeries brings up the advantages of minimal residual dead space left behind following a tubular spine surgery in discouraging cerebrospinal fluid collection, and thus its far-reaching complications. Targeted and specific management of focal neurological compression with minimal bony and soft tissue injury, and collateral damage to the paraspinal cuff of muscles, is a striking advantage with tubular surgeries. This benefit helps in preserving the stability provided by the envelope of paraspinal muscles and the axial skeleton. Added to this, if cases are carefully selected, a certain sub-set of patients with complex lumbar canal stenosis such as spondylolisthesis/scoliosis—who would otherwise need an extensive fusion surgery—can be treated with focal tubular decompression and sent home as day-care surgeries. The tubular retractor has a distinct advantage in obese patients.
Obesity has been associated with an increased incidence of surgical morbidity and mortality. Recent published studies have shown considerable variations in outcomes and complications in obese patients, with majority supporting a poorer surgical outcome. Wound infection rates are believed to be higher in obese patients. The large wound surface in the obese is possibly the reason for perioperative morbidity. In contrast, our experience shows that the prognosis of obese patients undergoing decompression surgery for lumbar canal stenosis using tubular micro-decompression is as good as in non-obese patients as far as outcomes are concerned.
The tubular retractor has changed the approach and thought process of spinal surgery. With my experience of more than 2,000 tubular surgeries over the last 10 years, I have seen its versatility and associated advantages. Results appear encouraging—we should push the tubular retractor envelope and stretch it to include as many indications as possible.
Arvind Kulkarni is a consultant spine surgeon at Bombay, Breach-Candy and Saifee hospitals in Mumbai, India.