Stand-alone anterior interbody fusion with the Synfix Evolution

Paul Heini

The Synfix Evolution secured spacer system (Fig 1,2) is a stand-alone anterior interbody fusion (ALIF) implant that is intended for use in patients with degenerative disc disease (DDD). It employs the Synfix implant technology, which has been used clinically in the Synfix LR implant since 2004. This technology is a zero-profile construct that includes four diverging locking screws. This design negates, in most circumstances, the need for additional fixation.

Implant overview

The Synfix Evolution implant has been designed to preserve the biomechanical stability of the Synfix LR implant by delivering the following:

  • An integrated titanium plate with four diverging locking screws that form a fixed angle construct, creating a wedge of bone designed as an anchor to potentially prevent fixation failure
  • A nonrigid connection between locking plate and PEEK spacer allowing for load sharing
  • PEEK spacer with elastic modulus similar to cortical bone
  • Self-tapping cortical threads

Fig 1 Synfix Evolution implant. Frontal view showing the zero-profile integrated titanium plate, fine and blunt tip self-tapping screws, and a graft retention ridge to enhance graft retention (a). The four lordotic angulations of 6, 10, 14, and 18 support sagittal alignment restoration (b).

Fig 2 Synfix Evolution implant posterior view (a). The implant uses a PEEK spacer to facilitate radiographic assessment of fusion, and comes in a wide range of implant heights. The bullet nose allows for ease of insertion (b). The deeper footprint option provides 3 mm of additional depth in the AP direction to accommodate varied anatomies (c-d).

Comprehensive implant portfolio

Fig 3: The Synfix implant portfolio includes:

  • 126 implants to support an optimal fit and fill of disc space and restoration of sagittal alignment (Fig 3)
  • 6 footprints
  • 6 heights
  • 4 angles

Instrumentation overview

The Synfix Evolution instruments were conceived and designed to simplify and minimize the number of instrumentation steps, while maintaining a high level of safety and precision (Fig 4).

Case provided by Paul Heini, Bern, Switzerland

Case: 47-year-old patient with chronic back pain

A 47-year-old woman was suffering chronic low back pain for several years, with severe pain attacks and with uncontrolled movements becoming increasingly disabling due to DD and erosive osteochondrosis at L4/L5. Condition after sciatica due to a disc herniation L4/L5, having nonoperative treatment. The MRI findings progressive compared to April 2014 are shown (Fig 5 and 6).

Anterior lumbar interbody fusion surgery was undertaken in July 2016 using the Synfix Evolution with InductOs (6 mg) (Fig 7). Intraoperative: routine operation, no complications. Postoperative: uneventful postoperative course.

6-month follow-up

By the planned 6-month follow-up, the patient was pain free and fully active. Evaluation with CT scans was undertaken, consolidation was starting (Fig 8).

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