The related outcome and complication rate in primary lumbar microscopic disc surgery depending on the surgeon's experience: comparative studies.

BACKGROUND CONTEXT

Studies concerning intraoperative complications and their influence on the clinical outcome of microscopic disc surgery are quite rare. Complication rates vary between 1.5% and 15.8%. A correlation between the surgeon's experience and the complication rate may be expected.

PURPOSE

To determine the influence of the surgeon's experience on the intraoperative complication rate in lumbar microscopic disc surgery.

STUDY DESIGN

Three studies are included: 1) retrospective analysis of intraoperative complications in microscopic disc surgery (N=1,872); 2) prospective follow-up study of microscopic disc surgery (N=583); 3) prospective evaluation of complication rates in microscopic disc surgery (N=90).

PATIENT SAMPLE

Patient data sets from 1,872 lumbar microscopic disc surgeries performed between January 7, 1981, and June 31, 2000, were examined in a retrospective study. A total of 463 patients, operated on between 1991 and 1996, were followed up by a questionnaire. Finally, a prospective controlled trial (N=90) was performed.

OUTCOME MEASURES

Such complications as incidental durotomy, wrong level exposure, or bleeding were analyzed based on the patient data sets by a blinded external evaluator. The rates of lower back pain and ischiatic pain were measured on a visual analogue scale at follow-up in Study 2 and Study 3. To measure the outcome of surgery in daily life activities and functional capacity, the Tegner activity level was calculated. In addition, a questionnaire with the Hannover score was used. The patient's social and economic status was also recorded.

METHODS

A total of 1,872 lumbar microscopic disc surgeries, performed between January 7, 1981 and June 31, 2000, were examined in a retrospective study. Intra- and perioperative complications were evaluated and related to the surgeons' level of experience. Patients in the first group (XL) were operated on by the most experienced surgeon (more than 500 microscopic discectomies before the beginning of the study). The L-group surgeons performed between 50 and 100 microscopic disc surgeries before the study. This group included a total number of seven surgeons during the 1981-2000 time frame. None of this group reached the experience level of 500 surgeries during the course of the study. A total of 463 patients, operated on between 1991 and 1996, were followed up. Finally, a prospective controlled trial (N=90) was performed. Injuries of the dura, nerve root, ventral structures and wrong level exposure, which had been detected and corrected during surgery, were analyzed. In the second and third study, the outcome was correlated to surgery and complications during surgery.

RESULTS

The rate of intraoperative complications showed a statistically significant difference between the groups. The comparison of both groups (n=1,872) with regard to the rate of intraoperative complications showed a statistically significant difference between 2.2% in the XL group and 10.7% in the L group (p< or =.001). Regarding work-related and socioeconomic factors, no significant difference in the outcome was seen.

CONCLUSIONS

Microscopic disc surgery requires a course of instruction and a considerable number of surgeries under supervision by experienced surgeons. To shorten the learning curve, a number of standardized surgery steps to clearly identify anatomical landmarks are helpful. During training, these landmarks can be checked by an experienced surgeon to minimize the rate of intraoperative complications. Initial postoperative ischiatic pain was correlated to an incidental durotomy with p<.001. For long-term results after disc surgery, however, socioeconomic and work-related factors are of greater importance in spinal disc surgery than the incidence of intraoperative complications.