Anterior + Posterior Spinal Fusion (AIS)

A combined anterior and posterior fusion means operating on the spine from both the front and the back. In my hands, for a stiff double major curve, the anterior part is a release of the lower, lumbar part of the curve, together with the placement of interbody cages at one or two levels; the posterior part is a full instrumented spinal fusion that corrects and holds the whole deformity. The two stages work together: the anterior work resets the shape and flexibility of the lower spine, and the posterior work completes and secures the correction across both curves.

The reason I turn to this approach in a stiff double major curve comes straight from my two aims. In these curves, the lower back is both rigid and often flattened, and correcting it well from the back alone can be difficult. By going in from the front first, I can release the lower curve and place an interbody cage at one or two levels. Those cages do two things that matter to me: they help me fully correct the lumbar profile in the coronal plane, and they let me rebuild the normal lumbar lordosis in the sagittal plane in a controlled, deliberate way. Restoring that segmental lordosis from the front tends to give a better and more reliable sagittal result in these difficult curves than trying to achieve it entirely from behind. There is a further benefit: working on the front column in this way often lets me save a level, keeping the fusion a little shorter than it would otherwise need to be.

Once the anterior release and interbody cages have reset the lower spine, I complete the correction with a posterior instrumented fusion. The posterior stage brings the whole spine — both the chest and the lumbar curves — into a balanced, level alignment and fixes it there while the bone heals. Combining the two approaches lets me get on top of a stiff, double curve that would resist correction from a single approach, and to do so while paying close attention to both the coronal and the sagittal shape. As with all deformity surgery, the nerves are monitored throughout, and both stages are planned carefully around the young person's general health.

The evidence supports combined anterior-and-posterior surgery for rigid, large or double major curves, while also explaining why it is now used selectively. In thoracolumbar and lumbar curves, the anterior approach reliably restores lumbar lordosis and saves a distal fusion level compared with the posterior approach, and biomechanical studies confirm that interbody cages markedly increase construct stiffness and help set the desired lordosis. Combining anterior release with posterior fusion improves the flexibility and correction of stiff curves and, in skeletally immature children, helps guard against later change in the shape of the spine. At the same time, modern all-pedicle-screw posterior constructs have become so powerful that many curves once treated with two approaches can now be corrected from the back alone, so the combined operation is reserved for the stiffest, largest curves and for situations where resetting the lumbar and sagittal profile from the front offers a real advantage. The literature also notes that double major posterior fusions can sometimes over-create lumbar lordosis, which is part of the argument for the more controlled anterior segmental correction in selected cases.

Because two approaches are involved, recovery is generally a little longer than after a single operation, and the team supports the young person throughout. Where the front of the spine and the chest or abdomen have been entered, a temporary drain may be used for a short time and breathing is supported and monitored closely early on. Beyond that, recovery resembles other fusions: a hospital stay of several days to over a week, active pain relief, help to get up and move as soon as it is safe, and a graded return to normal life over the following months while the fusion becomes solid. Many young people stand noticeably straighter and more balanced once a difficult double curve has been corrected. The spine is followed up over the long term.

• —Bullmann V, et al. Combined anterior and posterior instrumentation in severe and rigid idiopathic scoliosis. (PMC3175859)
• —Anterior/posterior instrumentation versus posterior alone for AIS curves more than 90 degrees. (PMID 16985469)
• —Systematic review and meta-analysis: does anterior-posterior fusion still have a role in severe thoracic AIS? (PMID 36777133 / PMC9880087)
• —Comparison of combined anterior-posterior versus posterior-only approach in scoliosis treatment. (PMC3939375)
• —Anterior selective lumbar fusion saving more distal segments vs posterior in Lenke 5 AIS: 8-year follow-up. (PMC8654659)
• —Surgical treatment of Lenke 5 AIS: comparison of anterior vs posterior approach. (PMC5027010)
• —Selective fusion in Lenke 5 adolescent idiopathic scoliosis. (PMID 30030189)
• —Surgical treatment of double major AIS can lead to excessive lumbar lordosis in the instrumented segments. (PMID 36795312)
• —Preventing the crankshaft phenomenon by combining anterior fusion with posterior instrumentation. (PMID 7676338)
• —Anterior thoracic scoliosis constructs: effect of rod diameter and intervertebral cages on construct stability. (PMID 14589202)
• —Biomechanical analysis of anterior scoliosis instrumentation: single vs dual rod with and without interbody support. (PMID 11923662)
• —Radiographic evaluation of selective anterior thoracolumbar or lumbar fusion for AIS. (PMC2518755)
• —Anterior surgery for adolescent idiopathic scoliosis (review). (PMC3566254)