THE LEARNING CURVE ASSOCIATED WITH LUMBAR MICRO-ENDOSCOPIC DISCECTOMY

Abstract

Introduction: Repetitive undertaking of a physical tasks results in an innate memory for that task. Development of this memory is an important component of surgical training and the ease and safety with which these changes are incorporated into a smoothly flowing procedure is represented by the so-called “learning curve”.

Changes in equipment and technology may radically alter the paradigm used by surgeons for completing the task of an operation. An example of this is the integration of endoscopy. The hand-eye orientation, field of view, angle of approach, binocularity of vision and skew of the visual field are all altered in lumbar micro-endoscopic discectomy (MED), when compared to open microdiscectomy.

Methods: This is a prospective observational study of the initial twenty-five cases of lumbar MED in the hands of a single surgeon. The twenty-five cases of open micro-discectomy immediately predating the current series are used as a cohort for comparison.

Results: A definite alteration in the ability of the surgeon to undertake a new method of discectomy occurred.

Three of the first seven cases of MED were converted to an open discectomy. None of the ensuing 18 cases was converted. The major learning outcomes to account for the change were familiarity with the radiological and videoscopic anatomy, and recognition of the importance of angles of approach.

The average time for surgery in the first ten cases was significantly longer than the second fifteen. The time for surgery in the latter group was not significantly altered from the open cohort group. The facets of surgery responsible for the increased time in the first group were techniques of exposing the nerve root, comfort of the extent of decompression of the nerve root and excision of the disc and comfort with the orientation and cleaning of the camera. The quality of illumination and visualisation of the operative field improved over the study although the significance of this could not be quantified.

Subjectively, surgeon “comfort” with the procedure developed relatively early in the “learning curve”.

There was no significant difference in clinical outcome and complications between the two groups.

Discussion: Minimal access techniques have been widely integrated into other fields of surgical endeavour. Open microdiscectomy is well accepted as a treatment for acute lumbar disc prolapse. The decision whether or not to change a surgeon’s operative technique should be based on the final anticipated clinical benefit of such a change compared to the cost and risk of changing. This study shows that there is a learning curve associated with lumbar MED, but that it can be integrated relatively easily into a surgical armamentarium.