Introduction: The aim of the study was to evaluate the safety and efficacy of the B-Twin System, and to compare it to intrapedicular screw fixation.

The B-Twin System comprises an expandable implant designed to be introduced into the intervertebral space. It is shaped as a 5-mrn diameter titanium tube and is inserted in a minimally invasive technique. Once in position within the intervertebral space it expands form 5 mm up to 15 mm, in a controlled manner, increasing intervertebral space height. Over 800 procedures were performed world-wide to date.

Methods: Sixty (60) patients indicated for fusion procedures due to mechanical back pain were operated with either the B-Twin System or with intrapedicular screws, 30 in each group. Minimal follow-up period was 1 year, ranging 12 to 19 months. VAS, Oswestry, and radiographs were evaluated.

Results: Overall, 60 patients (20 males and 40 females) participated in the study. Patients' mean age was 47 years, ranging 19 to 69. No statistical difference was noted between the groups when relating to age, sex and level of operation. Minor surgical complications developed in 2 B-Twin patients and in 4 intrapedicular screws patients. Physical examination prior to the procedure and at last follow-up did not reveal statistical differences between the two treatment groups. However, a much larger improvement in VAS score was noted in the B-Twin group compared to the intrapedicular screws group (a drop from 8.41 to 3.75 and from 8.33 to 5.66, respectively (p = 0.003)). In addition, the Oswestry questionnaire results showed better improvement in the B-Twin group (p less than 0.05).

Imaging studies performed for the B-Twin patients showed no translational or angular motion on flexion-extension radiographs, in all patients. No migration of the implant was noted. However, a reduction of 10% (0 - 20%) of the disc space height was observed.

Conclusions: Spinal fusion with the B-Twin implant is a safe and effective procedure. It reduces the operative sequela associated with open surgery. Significant pain reduction and increased functionality were observed at follow-up.

1 Spinal Care Unit, Meir Medical Center, Kfar-Saba, Israel
2 Orthopaedic B Department, Hillel Yaffe Medical Center, Hadera, Israel