Comparison of unilateral versus bilateral instrumented transforaminal lumbar interbody fusion in degenerative lumbar diseases.

BACKGROUND CONTEXT: Transforaminal lumbar interbody fusion (TLIF) has become a well-established technique that is traditionally performed with bilateral pedicle screw (PS) fixation. There are only a small number of case reports of unilateral instrumented TLIF. To our knowledge, there have been few well-designed studies comparing unilateral versus bilateral instrumentation with TLIF.

PURPOSE: To compare clinical and radiographic outcomes in a selected series of patients treated with unilateral versus bilateral PS instrumented TLIF.

STUDY DESIGN: Prospective randomized study in one unit.

PATIENT SAMPLE: A total of 80 patients were enrolled in this study. Thirty-seven patients (17 men and 20 women; average age 57.1 years) were randomized to the unilateral PS group and 43 patients (18 men and 25 women; average age 58.2 years) to the bilateral PS group.

OUTCOME MEASURES: The demographic data collected from both groups were gender, age, preoperative index diagnosis, degenerated segment, and single/double level of fusion. Operative time, blood loss, hospital time, and implant costs were also evaluated. Postsurgical pain and functional results were analyzed by the visual analog scale (VAS), modified Prolo (mProlo) scores, and Oswestry Disability Index (ODI). Radiographic examinations were carried out to assess total fusion rates, screw failure, and general complications.

METHODS: Patients were randomized into the unilateral or bilateral PS instrumented TLIF group based on a computer-generated number list. Patients were asked to return to hospital for follow-up at 4 weeks, 3 months, 6 months, 12 months, and thereafter once a year after surgery.

RESULTS: The mean follow-up was 25.3 months, with a range of 18 to 32 months. There were no significant differences between the two groups in terms of demographic data. The unilateral PS group had a significantly shorter operative time, less blood loss, and reduced implant costs compared with the bilateral PS group, although hospital time was the same for double-level cases. The average postoperative VAS, mProlo, and ODI scores improved significantly in both groups, with no significant difference between groups. The total fusion rate, screw failure, and general complication rate were not significantly different.

CONCLUSIONS: Unilateral PS instrumented TLIF is a viable treatment option generating better results, especially in terms of operative time, blood loss, and hospital time for single-level disease and implant costs. No decrease in the fusion rate or increase in the complication rate was observed in this group. Further improved study design and a longer period of follow-up are needed to confirm this effect.