SynFix is intended for use in the lumbar spine to facilitate fusion of the adjacent vertebrae. Its shape is based on the SynCage-LR with the addition of an integrated anterior fixation plate that re-establishes an anterior tension band following resection of the anterior longitudinal ligament. This fixation also provides additional stability in all directions of load and facilitates the use of this implant as a stand-alone device for the treatment of degenerative discs disease. The capacity to use this implant as a stand alone device enables the preservation of the vital posterior muscular structures to reduce the surgical morbidity associated with lumbar fusion surgery. First clinical experience in over 100 procedures in the past 18 months has shown that the construct is stable. Operation time and hospital stay was reduced significantly.
SynFix features a wedge shape, anatomical contour of the endplate interface, open structure for bone ingrowth. In order to achieve a stable fixation in flexion, extension and rotation, a titanium plate is integrated into the PEEK cage. Four locking head screws positioned in diverging angles provide purchase into the stronger peripheral bone near the anterior rim as the mechanical strong aspect of the vertebral bodies. The locking head screws provide considerable additional stability to the construct, similar to the widely used LCP principle in trauma. Biomechanical tests have demonstrated that the resultant stability is not significantly different from that of 360 fixation in flexion, extension and lateral bending, and is superior in torsion. These screws are self-tapping which improves the thread purchase.
SynFix-LR can be chosen in heights of 13.5, 15, 17 and 19 mm, with lordotic angles of either 8 or 12 and two different footprints of 32 26 mm or 38 30 mm. Specific instruments included in the SynFix-LR set serve to determine the correct implant size, to fill it with autologous bone, to insert the cage into the intervertebral space and finally to place the screws in the correct angles.
A 37-year-old female (65 kg and 170 cm tall) who suffered from back (L5/S1) and leg pain without neural compression for 2.5 years. She had a full range of conservative treatment and rehabilitation without benefit and reports a significant improvement in symptoms and function following surgery. She has returned to work with minimal restrictions in ongoing activities.
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