Design features

The design of the implant offers increased stability. Its pyramidal teeth provide primary resistance to implant migration, and the large graft volume allows for undercuts and openings in struts to increase graft volume. The middle strut design allows for an improvement to ratio of graft volume to endplate contact, and the diamond shaped anterior and anterolateral interface provides for optimal force distribution from the implant holder to the implant.
Other features include a self-distracting nose, which allows for ease of insertion. The tantalum radiographic marker pins enable visualization of the implant position during insertion.

Material: available in PEEK with 0.8 mm tantalum marker pins.
The comprehensive and competitive Syncage Evolution portfolio (Fig 2) boasts an asymmetric anatomical shape for more patient specific implants:

• Footprints: small (32.0 x 25.0 mm), medium (36.0 x 28.0 mm),
  large (40.0 x 31.0 mm)
• Heights: from 9.0 mm to 19.0 mm (9.0 mm, 10.5 mm, 12.0 mm,
  13.5 mm, 15.0 mm, 17.0 mm, 19.0 mm)
• Angles: 6 to 18 (6, 10, 14, 18)
• Asymmetric cranial and caudal surfaces with a 3-D convex shape for optimized endplate contact.

The improved instrumentation enhances ease of use compared with other systems in specific surgical phases.

Posterior release tool

The posterior release tool (Fig 3a) is used as an alternative to standard spreaders (Fig 3b).

Features include:

• Allows for progressive and controlled distraction and posterior release
• Broad tips avoid subsidence of the instrument
• Posterior release height is reproducible
• Changeable inserts for mobilization prevent over-distraction.

Evolution Squid

The evolution squid (Fig 4a) is used as an alternative to implant holders (Fig 4b):

• Distracts and inserts the implant in one simple step without impaction
• Offers multiple positioning options to recess implant in disc space
• Rails provided for safe implant guidance during insertion
• Thin blades prevent over-distraction during implant insertion.

Evolution trial rasps

Evolution trial rasps (Fig 5) have been specifically designed to help smooth the end-plates and create bleeding to aid with the inter-body fusion.

Case provided by Paul Heini, Bern, Switzerland

Case 1

A 75-year-old female patient presented with postoperative back pain. She had been initially operated on eight years earlier with a laminectomy and fusion from L2 to L4. This proved to be successful for a number of years until a second operation was required for secondary back pain and left side leg pain. An extension of the decompression was performed with stabilization and fusion from L1 to S1. The rationale for this operation was unknown and the surgery failed to improve her symptoms.

The problem to be addressed was the patients back pain and left side leg pain, inclusive of some weakness in her left foot. The pain was present upon weight-bearing, with a pain scale of 9. Her discomfort remained at night. The patient was of slim build and was in good general health. She presented with a limp from her left hip and the dorsiflexion of the left foot was weak (M4).

The preoperative standing image of the lumbar spine revealed a flat back with no obvious degeneration of the adjacent segment L1/L2 (Fig 6ab). The implants seemed regularly placed. After wide laminectomy, the spinal canal was open over the whole lumbar spine, illustrated on the MRI scan (Fig 6c).

A CT scan allowed a more detailed assessment (Fig 7). There was an obvious nonunion at L5/S1, with loose screws in the sacrum (red circle). Furthermore, there was instability at L4/L5 as the intervertebral disc presented with an important vacuum phenomenon (asterisk). Foraminal stenosis at L5/S1 (not shown) seemed to be the reason behind the persistent leg pain.

The treatment plan was an anterior height restoration and fusion of L5/S1 and L4/L5. A posterior revision surgery was not considered due to the wide decompression and obvious scar formation. For the correction of level L4/L5, an oblique anterolateral approach (OLIF) was selected due to considerable calcification of the aorta and the iliac vessels. At the L5/S1 level, a straight anterior approach was selected and an additional plate fixation (ATB) was performed.
At level L5/S1, a large cage with an angulation of 14 was selected and for L4/L5, a large cage with an angulation of 10 was placed. In order to perform a fusion, the cages were each filled with 6 mg of BMPII.

From six months postoperatively, leg discomfort decreased. Within an additional four months, pain disappeared completely and both foot and hip weakness recovered. The back pain persists to a certain extent but is not impedingthe patient in her daily activities. The x-ray taken 10 months after the anterior revision surgery revealed a complete and solid fusion on both levels (Fig 8). This is confirmed by the appearance of dense bone in the radiolucentcage.

Case provided by Khai Lam, London, UK

Case 2

A 19-year-old high-level college hockey player had experienced 12 months of severe lower back pain (LBP), and was unable to play sport due to high disability and pain (Fig 9). Nonoperative treatment with physiotherapy and injections had failed.

The CT showed bilateral L5 spondylolysis with grade I spondylolisthesis (Fig 10).

The patient underwent minimal access L5/S1 anterior interbody fusion with BMP followed by minimally invasive Matrix percutanous screw fixation (Fig 11).

Case provided by Khai Lam, London, UK

A 23-year-old female college student had experienced 3 years of severe LBP with some right S1 sciatica. She presented with high disability, failed nonoperative treatment, injections, and pain killers. She was unable to lead a normal life and conduct activities of daily living.

The sagittal and axial T2-weighted MRI showed grade III disc degeneration with diffuse right-sided disc bulging (Fig 12).

The postsurgery AP and lateral images show stand-alone locked L5/S1 anterior fusion using Syncage Evolution with BMP-2 and an Aegis locking plate (Fig 13).