European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
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Restoring a stable anterior column is essential to achieve normal spinal biomechanics. A variety of mechanical spacers have been developed and advocated for both anterior and posterior approaches. The ability to radiographically assess the "biology" of bone incorporation in these mechanical (metal) spacers is an inherent limitation. ⋯ Additional posterior instrumentation may increase the stability of the motion segment, but the degree of stability necessary to achieve a biological union remains unclear. The incorporation of these biological cages can be monitored by conventional radiographic techniques. The method of insertion preserves the vertebral end-plates and can be performed by a minimally invasive or standard open procedure.
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The coincidental development of minimal intervention techniques for carrying out anterior lumbar spinal fusion and the introduction of cages to provide mechanical support of introduced bone graft led to the development of a type of cage suitable for both minimal intervention use (laparoscopic) and for the standard open procedure (the BAK cage). Reported results concentrated in the main on feasibility, safety and fusion rate achieved, rather than clinical outcome. ⋯ There was no long-term benefit from the laparoscopic procedure. Laparoscopic insertion at the L4/5 level was attended by a greater incidence of complications, and had a longer learning curve.
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This review will summarize the major efforts currently underway to develop osteoinductive bone graft substitutes for minimally invasive spine fusions. The primary categories of substitute include purified bone growth factors, recombinant bone growth factors, and growth factors delivered by gene therapy approaches. Clinical trials are underway for the purified and recombinant bone growth factors and pre-clinical studies have yielded promising results for a variety of gene therapy techniques for generating bone.
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Meta Analysis
Anterior thoracoscopic spine release in deformity surgery: a meta-analysis and review.
Videoassisted thoracoscopic surgery (VATS) allows the surgeon to perform an anterior thoracoscopic spine release for spinal deformities. It is an alternative to open thoracotomy. Several years after its introduction the present author gives an update on the indications, surgical techniques, results, and complications of this new technology. ⋯ The VATS procedure has been used with success in most series for pediatric curves (average Cobb angle of 65 degrees or kyphosis of 75 degrees). No report of the surgical outcome (balance, rate of fusion, rib hump correction, cosmetic correction, pain, and patient satisfaction) was available for any series. Further prospective study including these parameters will be required to determine the real benefit of such procedures to the patient, bearing in mind that the correction of spinal deformities is the result of the surgeon's experience, skill, and the available technology.
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Comparative Study
The anatomic variability of human cervical pedicles: considerations for transpedicular screw fixation in the middle and lower cervical spine.
Transpedicular screw fixation has recently been shown to be successful in stabilizing the middle and lower cervical spine. Controversy exists, however, over its efficacy, due to the smaller size of cervical pedicles and the proximity of significant neurovascular structures to both lateral and medial cortical walls. To aid the spinal surgeon in the insertion of pedicle screws, a number of studies have been performed to quantify the gross dimensions and angulations of the cervical pedicle. ⋯ The pedicle slices were found to exhibit substantial variability in composition and shape, not only between individual spines and vertebral levels, but also within the pedicle axis. However, the lateral cortex was consistently found to be thinner than the medial cortex in all samples. These physical findings must be noted by surgeons attempting transpedicular screw fixation in the cervical spine.