Anterior Lumbar Interbody Fusion (ALIF) - Sam Church 7/1/2002

 

The main indication for lumbar fusion is instability. American Medical Association definition of spinal instability is 'an anterior slip of >5mm or a difference of >11 degrees (15 degrees for L5/S1) angular motion between two adjacent segments.' Symptoms of instability include giving way, 'catching' and lower back pain but these do not correlate well with the xray findings described above and are often complicated by concomitant spinal stenosis, disc herniation and psychiatric problems.

 

Lumbar fusions are also commonly performed for 'discogenic' back pain or in combination with discectomies/decompressions. This is controversial and the spinal community is split over whether there is satisfactory evidence to support this. Campbell 's states that 'the indications for lumbar fusion should be independent of the indications for disc excision for sciatica'. However, the other camp believes that disc degeneration is the precursor of instability so it's all part of the same pathological process. Besides, most of the research on lumbar fusion has been carried out on patients with disc disease as this is far more common than spondylolisthesis.

 

Other indications for lumbar fusion include the treatment of other failed spinal procedures, certain spinal deformities, infections, fractures and tumours.

 

Methods of fusion include interbody, posterior, posterolateral and intertransverse (or various combinations of the above). The interbody fusion is theoretically biomechanically superior to the others as the graft is placed in the centre of segmental motion thus minimising the lever arm effect. Interbody fusions can be approached anteriorly or posteriorly. Although the anterior approach has the disadvantage of requiring a surgeon practised in laparotomies, once in there the dissection is easier, you can completely excise the disc and the (posterior approach) complications of posterior element pain and scarring within the spinal canal are avoided. Laparoscopic ALIF and retroperitoneal endoscopically assisted minilaparotomy (REAM) for ALIF are very trendy now although there are no long-term results available yet.

 

Interbody fusions can be performed using tricortical iliac crest graft, fibular strut grafts, femoral ring grafts or cages (with bone graft packed inside). Most surgeons seem to be steering towards using cages (metal or carbon fibre) these days as they're quicker and easier (although more expensive) and they are more reliable at restoring disc space height thereby reducing subluxed facet joints and enlarging nerve root foramina. Autograft and/or allograft can be used and, not surprisingly, this is the subject of much debate.


 

 

 

 

 

Brief

Turner et al                        Acta Orthop Scand                                1993

Title

Meta-analysis of the results of lumbar spine fusion

Authors

Turner JA, Herron L, Deyo RA

Reference

Acta Orthop Scand (Suppl 251) 1993; 64: 120-2

Summary

Meta-analysis of 47 articles, comparing indications for and techniques of lumbar fusion. Overall 68% success rate but no fusion method was better or worse than the others. Only sig diff was that ALIF had lower fusion rate than the others but clinical outcome was still as good. Concludes that the waters are still very muddy and more work needs to be done.

Critique

Good design & inclusion criteria. Needed doing. Pity that their only real conclusion was that there were no conclusions.

 

 

 



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Brief

Inoue et al                                   CORR                                              1984

Title

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