Minimally invasive removal or revision of lumbar spinal fixation

There are both absolute and relative indications for the removal of pedicle screw fixation in the lumbar spine. Whatever the reasons are, removal of this hardware has required a surgical dissection that has been generally as extensive as the one used for their initial placement. These dissections are always disabling in the short term. In fact, the magnitude of this disabling pain can be significant enough so as to effectively eliminate screw removal as a logical treatment option for many conditions where indications for removal are only relative. Percutaneous pedicle screw fixation has served to amplify the stakes associated with this dilemma. In fact, this new technique makes the need for a less invasive method of pedicle screw removal greater now than ever.

This paper describes a minimal access surgical technique for pedicle screw construct removal that employs the tubular retractor system that was originally developed for microendoscopic discectomy.

This case study represents a summary of the surgical experience gained from the first 10 patients to have undergone removal or revision of pedicle screw constructs by this minimally invasive method.

A retrospective analysis of pre- and postoperative clinical data was gathered from the hospital records. Surgical times and blood loss were also extracted from these records. The procedure is described in detail. Interpretation of the surgical parameters and clinical effects are discussed.

Six patients presented with a radiculopathy secondary to a misdirected pedicle screw. Two of these patients were admitted for simple removal. The four remaining patients who had undergone percutaneous pedicle screw fixation developed acute radicular pain from a misdirected screw. These patients underwent revision of their constructs by this method. Screws were also removed unilaterally in four other patients as the initial phase to revision or additional surgery. All procedures were performed through 16 mm tubular retractors. Operative time averaged 33 minutes for the group,and it ranged between 22 and 40 minutes. Hospital length of stay averaged I day for the group. Hospital stay averaged only 0.8 hospital days for the patients in whom screw removal was the primary goal. At 1 month after surgery no patient felt limited by incisional pain. No complications occurred.

Unlike most other minimal access surgical procedures, the learning curve for this procedure appears to be relatively flat. Removal of pedicle screw fixation in the manner described proved to be simple and straightforward. The benefits are dramatic and immediate. It is possible to complete the procedure within minutes, and the pain produced is best described as inconsequential. This minimally invasive technique radically alters both the intraoperative and postoperative courses for those who face pedicle screw removal. The disadvantages associated with the standard open approach are reduced to the production of mild short-term discomfort and an exposure to the potential risks of brief anesthesia and the possibility of a surgical infection. Considering that hospital stay should be limited to I day or less and that surgical times are less than I hour, minimally invasive removal or revision of hardware should reduce overall costs significantly.