gms | German Medical Science

Objective: The ARCA-MEDICA^® Synchro is a modified TLIF-Cage which is fitted with a mechanism that allows the cage to take a V-shape after implantation into the disc space. The unique property of this cage is its slim profile, yet a relatively large foot print as well as a flexible arm that enables to position the cage to the contralateral side. The aim of our retrospective study was to investigate the handling and positioning of this intervertebral implant.

Method: 29 patients (mean age 64 years, range 42-83, 15 female, 14 male) with degenerative instability of the lumbar spine were treated between August 2013 and August 2014 by dorsal spondylodesis using a screw-rod-system and the ARCA-MEDICA^® Synchro TLIF-Cage. 16 of 29 patients had developed segmental instability secondary to previous operations.

Results: 29 patients were instrumented, 22 at one lumbar level, 7 at two levels (34 TLIF- and 4 PLIF-Cages). The handling of 26 TLIF-Cages (76%) in 20 patients was satisfactory with correct positioning of the cages (cage dimensions 7-12mm high) in the midline and the desired retroflexion of the flexible arm on the contralateral side. In 3 patients the TLIF-Cages had a lateral position because of scarring of the disc space at the contralateral side caused by previous surgeries. In one patient the TLIF-Cage could only be inserted after opening and distraction of the previously operated contralateral side. In 3 patients the flexible arm of the TLIF-Cage did not show the desired retroflexion. One patient was treated with the flexible TLIF-Cage at the level L4/5, but with 2 PLIF-Cages (AMT/Medtronic^® Fuse Cages) at level L5/S1 because of a narrow disc space, which did not allow implantation of a flexible TLIF-Cage. In another case the strategy was switched intraoperatively from TLIF to PLIF-Cages because of a curved shape of the disc space and insufficient fit of the TLIF-Cage. No patient had to undergo revision surgery. We had no cage-related nerve root or dural injury.

Conclusions: By insertion of the ARCA-MEDICA^® Synchro only one side of the spinal canal and disc space has to be opened. This is time saving particularly in patients with previous spine surgery and epidural fibrosis. In comparison to standard TLIF-Cages the flexible cage requires a significant smaller decompression of the foraminal region for the insertion. The major drawback of this implant is the difficult implantation technique in cases with severely curved endplates, a very narrow disc space or severe scarring of the contralateral side.