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Journal of Long-Term Effects of Medical Implants
SJR: 0.332 SNIP: 0.491 CiteScore™: 0.89

ISSN Print: 1050-6934
ISSN Online: 1940-4379

Journal of Long-Term Effects of Medical Implants

DOI: 10.1615/JLongTermEffMedImplants.v17.i3.50
pages 217-227

Posterior Lumbar Interbody Fusion versus Circumferential Fusion Using the B-Twin Expandable Spinal System

George S. Sapkas
First Department of Orthopaedics, National and Kapodistrian University of Athens, School of Medicine, ATTIKON University Hospital, Athens, Greece
George S. Themistodeous
Consultant Orthopaedic Surgeon, Athens Greece
Vasileios C. Zachos
Consultant Orthopaedic Surgeon, Athens Greece
George Kelalis
Consultant Orthopaedic Surgeon, Athens Greece


We reviewed the medical files of 32 patients with degenerative disc disease, spinal stenosis, and spondylolisthesis who underwent posterior lumbar interbody fusion using the B-Twin system. In 12 of these patients, posterior lumbar interbody fusion has been supplemented with posterior lumbar-instrumented fusion (circumferential fusion) because of spinal instability. Clinical and functional outcomes were assessed. The quality of fusion and disc height were recorded. The mean follow-up was 36 months (range, 18 to 42 months). At the latest examination, clinical improvement and fusion were statistically significant in both groups; the mean Oswestry disability index improved from 55% to 24%, and to 22% in the patients with more than 20 months follow-up; the mean Rolland-Morris disability questionnaire improved from 52% to 29% (p < 0.001); 95.6% (22/23) of the levels managed with the B-Twin system alone and 92.9% (13/14) of the levels managed with circumferential fusion showed solid fusion; and the intervertebral disc height increased from 8.1 ± 0.74 mm to 11.4 ± 0.93 mm in the B-Twin group and from 7.7 ± 0.75 mm to 10.6 ± 0.91 mm in the circumferential fusion group. However, in comparing the two groups there was no statistical significant difference. The B-Twin system is safe and effective for the management of degenerative disc disease as a stand-alone device. The combination with posterior lumbar-instrumented fusion systems for circumferential fusion yields statistically significant differences in fusion rate and functional outcome.