Anatomical basics in regard of minimal invasive lumber spine procedures
W Rauschning. Anatomical basics in regard of minimal invasive lumber spine procedures. The Internet Journal of Minimally Invasive Spinal Technology. 2008 Volume 3 Number 4.
Employing the author's Uppsala Cryoplaning Technique over 400 human spine specimens have been studied in considerable detail during a 25-year period of time. Typically portions of the spine (craniocervical, cervical, thoracic, and lumbosacral) were harvested during the course of clinical-pathological or forensic routine autopsies, freezing the specimens in situ before removal. The specimens were radiographed and CT-scanned before they were sectioned on a heavy-duty sledge cryomicrotome to facilitate exceptionally accurate radiographic-anatomical correlations. High-resolution slides were obtained from the surface of the specimen during the cryoplaning process, typically at submillimeter intervals and in perfect pin-registration. In addition to a vast variety of normal spines, virtually all types of pathological conditions were studied, including tumours and metastases. More than 50 spines from former patients who had had spinal surgery performed, were also studied in great detail.The lecture will begin with a brief outline the normal and functional anatomy of the highly dissimilar portions (storeys) of the spine, emphasizing and highlighting surgically relevant relationships, anatomical features that are not well or correctly described in the standard anatomy textbooks, and also hitherto unknown anatomical structures. To mention a few: the epidural venous sinusoids in the cervical epidural space which is devoid of fat (!), the uncovertebral pseudojoints and their traumatic and degenerative pathology, the variability of the pedicles and their relationship to the suprajacent and infrajacent nerves, the detailed anatomy of the lumbar lateral recesses, the functional pathomorphology of lumbar spinal stenosis, new concepts of the intrinsic structure of the intervertebral discs, the overrated posterior longitudinal ligaments and supraspinous ligaments, the tendinous reinforcements of the lumbodorsal fascia adjacent to the spinous processes.Due to their vast dissimilarities, the various portions of the spine will be dealt with separately: the craniocervical junction, the subaxial cervical spine, the cervicothoracic junction, the thoracic spine, thoracolumbar junction, lumbar spine and lumbosacral junction, both in terms of overview anatomy, surgical approach considerations, and pathological conditions typical and common for each region, including trauma, degenerative changes, neoplasms and metastases, deformities and examples of surgical interventions are detailed and subjected to a critical review with respect to adequacy of the surgical approach and appropriateness of the surgical procedure for each given condition.In the craniocervical and cervical spine a variety of pathologies will be shown, including a comprehensive study on whiplash and radiographically "hidden" or "occult" cervical spinal injuries. The results of a comparative clinical study on anterior versus posterior plate fixation are presented that conclusively shows that the anterior fascial-plane-dividing atraumatic and virtually bloodless surgical approach carries significantly less perioperative and late-outcome morbidity. Patients who had had posterior plating had more complaints and a longer rehabilitation, and also invariably long-term sequelae such as neck fatigue, tiredness and problems balancing their heads toward the late afternoon. This is probably due to surgical interference with proprioception due to severance of the short posterior neck muscles. By contrast, all patients who had had anterior surgery had an uneventful recovery without any late sequelae.We also conducted a cadaveric-experimental study on various posterior plating techniques, including the Roy- Camille, Louis, and Magerl plating techniques that unequivocally showed that the screw insertion trajectories proposed by Magerl carry no risk for damaging the dorsal root ganglia, root bundles or the vertebral arteries. Postsurgical cases studies will include both surgeries performed for acute trauma, myelopathy, spondylosis and a variety of metastases. In the vast majority of patients who had had posterior exposures, large-volume scar transformation of the short deep neck muscles were observed. This scarring always extended several levels above and below the amended exposures/fusions which probably account for the patients' chronic neck disabilities.The cervicothoracic and thoracic spine will be dealt with in terms of the peculiarities of the thoracic outlet (inlet) with respect to adequate approaches, the role of the brachial plexus and the complexity of the composite transverse processes (transverse process proper, rib-anlage, intertransverse bar). The costotransverse and costocentral articulations are important for surgical approaches, and the anatomy of the prevertebral mediastinum is outlined for endoscopic surgery reference. Postsurgical case studies encompass ankylosing spondylitis, fractures and metastases.The thoracolumbar junction and lumbar spine anatomy/pathology presentation includes a variety of fracture types, and considerations regarding approaches and repair techniques and osteosynthesis. Similarly, anterior versus posterior fixation techniques for osteolytic and osteoblastic metastases are critically reviewed with respect to the biology of the malignancy, its propagation into the vertebral column and invasion or infiltration into the vital neurovascular spinal elements. The "adequacy" of minimally interventional palliative surgery for metastases is demonstrated in a comprehensive study of our own, along with a plethora of pathoanatomical and postsurgical documentation of decompression and stabilisation techniques. In the lumbar and lumbosacral spine the cascade of degenerative disc disease (DDD) is demonstrated in view of the currently available surgical treatment options. The pathoanatomy of "low-back-pain" and "radiculopathy" is mirrored against current treatment options, ranging from chemonucleolysis, percutaneous disc ablation, a variety of laser disc ablation options, coblation, and IDET, to hydrogel nucleus prosthesis, PDN, a wide array of fusion techniques such as cages for PLIF and ALIF applications, femoral ring and precision crafted allograft fusions and artificial disc prostheses. As an intriguing alternative, the concept of neutral dynamic distractive stabilisation of the lumbar spine in painful mechanical dysstabilities and spinal stenosis in younger patients is briefly outlined.We also conducted a cadaveric-experimental study pertaining to posterior percutaneous or endoscopic surgical approaches to the intervertebral discs. The study clearly showed that any uni or biportal approach to the lower lumbar spinal discs carries potential risk for injury or violating blood vessels or neural structures, in particular the delicate dorsal root ganglia.In all postsurgical specimens of patients who had had posterior lumbar surgery, extensive scar transformation of the back muscles was consistently observed. Not only were the erector trunci muscles affected, but also the deep short oligosegmental muscles which account for the proprioception and fine-tuning of segmental mobility. In short as well as in long instrumentation, the scarring extended one or two levels above and below the intended instrumentation. All back muscles are contained in a non-expansile osseoaponeurotic compartment. When contracted, they constitute a powerful "dorsal soft tissue column" which stabilises the lumbar spine. Surgery must minimise violation of these muscles to avoid failed back surgery sequelae.