Biomedical subjects
Publications and source records attributed to Marek Szpalski.
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Autogenous bone grafts from the iliac crest have long been the gold standard for repair and reconstruction of bone; however harvesting of the grafts from the iliac crest is associated with donor site morbidity, particularly chronic pain. The bone morphogenetic proteins (BMPs) are soluble bone matrix glycoproteins that induce the differentiation of osteoprogenitor cells into osteogenic cells and have the potential to act as autogenous bone graft substitutes. BMP-2, which can be produced with recombinant technology, is highly osteoinductive, inducing bone formation by stimulating the differentiation of mesenchymal cells into chrondroblasts and osteoblasts. At present, more than 1,000 patients have received rhBMP-2 in clinical trials for acute open tibial fracture and interbody fusion procedures for the treatment of degenerative disc disease. Data suggest that rhBMP-2 therapy may offer an effective alternative to autogenous bone graft for recalcitrant bone unions and spinal fusion, obviating donor site morbidity.
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The problems linked to blood loss and blood-sparing techniques in spine surgery have been less studied than in other fields of orthopedics, such as joint-replacement procedures. Decreasing bleeding is not only important for keeping the patient's hemodynamic equilibrium but also for allowing a better view of the surgical field. In spine surgery the latter aspect is especially important because of the vicinity of major and highly fragile neurologic structures. The techniques and agents used for hemostasis and blood sparing in spinal procedures are mostly similar to those used elsewhere in surgery. Their use is modulated by the specific aspects of spinal approach and its relation to the contents of the spinal canal. Blood-sparing techniques can be divided into two categories based on their goals: either they are aimed at decreasing the bleeding itself, or they are aimed at decreasing the need for homologous transfusion. Various hemodynamic techniques, as well as systemic and local drugs and agents, can be used separately or in combination, and their use in the field of spine surgery is reported. The level of evidence for the efficacy of many of those methods in surgery as a whole is limited, and there is a lack of evidence for most of them in spine surgery. However, several blood-saving procedures and drugs, as well as promising new agents, appear to be efficient, although their efficacy has yet to be assessed by proper randomized controlled trials.
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Cement augmentation of hip lag screws to avoid cut-out displacement is classically described, along with a number of technical drawbacks. In a series of six elderly patients with hip fractures in osteoporotic bone, we illustrate catheter-assisted delivery of limited amounts of a new bisphenol-a-glycidyl dimethacrylate (bis-GMA)-based composite into hip compression screw threads, enabling significant increase in insertional torque compared with unaugmented screws. In two patients, unaugmented screws that did not initially purchase were tightened with a minimum torque of 1 N-m after augmenting with bis-GMA-based composite. No screw or femoral head displacement relative to baseline (2 days postoperative) was seen in any patient on serial x-rays taken up to 6 months after surgery. This technique adds approximately 10 minutes to surgery time. Advantages of bis-GMA-based composite over traditional PMMA augmentation include mixing on-demand, the ability to make repeated injections over extended periods in the event of femoral head perforations (in one patient in this series), precise placement of adequately small volumes of material, and a lower exotherm. Potentially, this bis-GMA-based composite may reduce the frequency of cut-out complications by enhancing bone-implant interface.
Lumbar spinal stenosis is a common condition in elderly patients and also one of the most common reasons to perform spinal surgery at an advanced age. Disc degeneration, facet degeneration and hypertrophy, and ligamentum flavum hypertrophy and calcification usually participate in the genesis of a stenotic condition in the elderly. These changes can lead to symptoms by themselves or decompensate a preexisting narrow canal. Although some lesions are more central or more lateral, this classic dichotomy is less present in the elderly patient, in whom the degenerative process usually encroaches both central and lateral pathways. Some less common causes of lumbar spinal stenosis are found in the aging subject, such as Paget's disease. However, it must be stressed that so-called stenotic images (sometimes severe) are present on imaging studies in a great number of symptom-free individuals, and that the relationship between degenerative lesions, importance of abnormal images, and complaints is still unclear. Lumbar stenosis is a very common reason for decompressive surgery and/or fusion. Various conditions can lead to a narrowing of the neural pathways and differential diagnosis with vascular troubles, also common in the elderly, can be challenging. The investigation of stenotic symptoms should be extremely careful and thorough and include a choice of technical examinations including vascular investigations. This is of utmost importance, especially if a surgical sanction is considered to avoid disappointing results.
Canal stenosis is now the most common indication for lumbar spine surgery in elderly subjects. Degenerative disc disease is by far the most common cause of lumbar spinal stenosis. It is generally accepted that surgery is indicated if a well-conducted conservative management fails. A meta-analysis of the literature showed on average that 64% of surgically treated patients for lumbar spinal stenosis were reported to have good-to-excellent outcomes. In recent years, however, a growing tendency towards less invasive decompressive surgery has emerged. One such procedure, laminarthrectomy, refers to a surgical decompression involving a partial laminectomy of the vertebra above and below the stenotic level combined with a partial arthrectomy at that level. It can be performed through an approach which preserves a maximum of bony and ligamentous structures. Another principle of surgical treatment is interspinous process distraction This device is implanted between the spinous processes, thus reducing extension at the symptomatic level(s), yet allowing flexion and unrestricted axial rotation and lateral flexion. It limits the further narrowing of the canal in upright and extended position. In accordance with the current general tendency towards minimally invasive surgery, such techniques, which preserve much of the anatomy, and the biomechanical function of the lumbar spine may prove highly indicated in the surgical treatment of lumbar stenosis, especially in the elderly.
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OBJECTIVE: To clarify the biomechanical indicators of single- and multi-level stenosis and to determine the biomechanical outcome of selective conservative decompression. DESIGN: This study is a prospective clinical trial examining trunk function in spinal stenosis patients operated using a conservative procedure in an orthopaedic clinic. BACKGROUND: Although several clinical studies have examined the instability and motion characteristics of operated lumbar spinal canal stenosis, few if any studies have prospectively examined the biomechanical outcome of lumbar spinal canal stenosis surgery. METHODS: Comprehensive pre- and post-operative trunk dynamometer strength and motion analysis tests were performed on 36 patients operated for lumbar canal stenosis. Surgical treatment efficacy was evaluated within a three variable crossed factorial design considering stenosis classification, number of operative levels, and changes in several trunk biomechanical outcomes from pre- to post-operative assessment. Patients were evaluated after a minimum one-year follow-up. RESULTS: Pre-operatively there were no differential effects associated with stenosis classification or number of operated levels. There was a significant post-operative increase in isometric trunk extension torque and flexion-extension power and a return to a more normal trunk extension-flexion torque ratio. Patients with mixed, single level stenosis demonstrated greater trunk extension power both pre- and post-operatively compared to other patients. CONCLUSIONS: Conservative surgical treatment of lumbar spinal stenosis produced a marked improvement in the functional mechanical status of the low back. RELEVANCE: This study assists clinicians and researchers to understand trunk function following conservative surgical treatment of lumbar spinal stenosis.
Degenerative disc disease is one of the most frequently encountered spinal disorders. The intervertebral disc is a complex anatomic and functional structure, which makes the development of an efficient and reliable artificial disc a complex challenge. Not only is the disc function arduous to reproduce, but there are important consequences associated with the conception and the choice of materials that will have to bear the loads. Biochemical problems have complicated things even more. Two different principles have been applied in the realisation of a discal replacement: a metallic and/or polyethylene prosthesis allowing mainly mobility or a prosthesis enabling the reproduction of viscoelastic properties. Of course some devices attempt to combine both principles. In this paper we will try to present, in chronological order, an overview of the designs published in the literature as well as in the patents granted in this field. The very fact that such a long list of implants, based on highly varied principles, has been proposed, and that only very few have reached the level of animal models, let alone human implantation, clearly demonstrates how challenging the task of designing an intervertebral disc replacement is. Proper randomized controlled trials are now on the way, and should help in assessing the efficacy and real place of spine arthroplasty in the treatment of spinal disorders. Only then will spinal surgery join the list of successful joint replacements.
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Surgery for rheumatoid arthritis (RA) and spondyloarthropathies is a palliative surgery, and testifies to the failure of conservative treatment. In RA, surgery is generally used to deal with upper cervical instability and peridens pannus compression. These complications can have dramatic neurological consequences and can even be life threatening. Every effort must be made to avoid unnecessary surgery but, if needed, the indication must be precise and timely to be efficient. Instrumented fusion is indicated but the need for pannus excision is discussed. In ankylosing spondylitis (AS), major deformity will be the indication for corrective surgery if this deformity induces a marked decrease in the field of vision, thoracicy or abdominal problems or respiratory and mandibular troubles in the cervical spine. Different types of osteotomies with instrumented fixation are described. In AS. surgery is also indicated in fractures that are potentially unstable. At the cervical level these fractures are a surgical emergency. Neurological compressions and spondylodiscitis are other reasons for surgery in AS. Complications of other spondyloarthropathies, which include accompanying psoriasis, reactive arthritis, enteropathic arthritis or Behcet's syndrome are occasionally treated surgically along the same lines as RA or AS. Surgery for spinal inflammatory disorders involves major procedures with a high rate of severe complications. The indications for this type of surgery must be extremely precise and both the surgeon's and the patient's expectations must be clear and realistic. The surgery should only be performed by a surgeon who is experienced with this type of patient and procedure but, furthermore, it should also only be camed out in a centre with a team of neurologists, anaesthetists, nurses and physical therapists who have the expertise to work with these pathologies and these often severely debilitated patients. Only under these conditions will the outcome justify the burden and the risks.
Synthetic bone void fillers are gaining acceptance as graft extenders in spinal surgery. One such product is an ultraporous formulation of nanometer-sized particles of beta-tricalcium phosphate (beta-TCP). An ongoing prospective open-label, randomized, observer-blinded, comparative study evaluated the efficacy and safety of a novel beta-TCP bone void filler as an additive to autogenous bone graft material in patients undergoing spinal fusion. Posterolateral instrumented or noninstrumented spinal fusion was performed at a single level or multiple levels with or without additional interbody fusion. Patients received autogenous bone on 1 side and autogenous bone augmented with extender (in a 1:1 ratio based on the weight of the materials) on the opposite side, each patient serving as his or her own control. The graft material was placed at the level of the facet joints and the intertransverse processes. Patients were randomized to receive the extender on either the right or the left side. This article is a preliminary report on patients who have undergone this procedure.
For more than a century, fracture repair has been augmented with autogenous cancellous bone grafting, which supplies 3 requisite properties: growth factors for osteoinduction, progenitor stem cells for osteogenesis, and scaffolding for osteoconduction. However, disadvantages to using autogenous bone include procurement morbidity, longer operative time, and limited availability. Allograft is more readily available but does not supply osteoinductive or osteogenic properties. Better alternatives for bone grafting currently include autologous bone marrow, ceramics, allograft demineralized bone matrix, and regulatory growth factors; however, none of these fulfills all 3 requisite properties. Replacement or augmentation of autograft with a calcium phosphate-based composite graft, which combines the best elements of each component into a single engineered graft, is discussed.