From Wolff's law to the Utah paradigm: insights about bone physiology and its clinical applications.
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Efforts to understand our anatomy and physiology can involve four often overlapping phases. We study what occurs, then how, then ask why, and then seek clinical applications. In that regard, in 1960 views, bone's effector cells (osteoblasts and osteoclasts) worked chiefly to maintain homeostasis under the control of nonmechanical agents, and that physiology had little to do with anatomy, biomechanics, tissue-level things, muscle, and other clinical applications. But it seems later-discovered tissue-level mechanisms and functions (including biomechanical ones, plus muscle) are the true key players in bone physiology, and homeostasis ranks below the mechanical functions. Adding that information to earlier views led to the Utah paradigm of skeletal physiology that combines varied anatomical, clinical, pathological, and basic science evidence and ideas. While it explains in a general way how strong muscles make strong bones and chronically weak muscles make weak ones, and while many anatomists know about the physiology that fact depends on, poor interdisciplinary communication left people in many other specialties unaware of it and its applications. Those applications concern 1.) healing of fractures, osteotomies, and arthrodeses; 2.) criteria that distinguish mechanically competent from incompetent bones; 3.) design criteria that should let load-bearing implants endure; 4.) how to increase bone strength during growth, and how to maintain it afterwards on earth and in microgravity situations in space; 5.) how and why healthy women only lose bone next to marrow during menopause; 6.) why normal bone functions can cause osteopenias; 7.) why whole-bone strength and bone health are different matters; 8.) why falls can cause metaphyseal and diaphyseal fractures of the radius in children, but mainly metaphyseal fractures of that bone in aged adults; 9.) which methods could best evaluate whole-bone strength, "osteopenias" and "osteoporoses"; 10.) and why most "osteoporoses" should not have bone-genetic causes and some could have extraosseous genetic causes. Clinical specialties that currently require this information include orthopaedics, endocrinology, radiology, rheumatology, pediatrics, neurology, nutrition, dentistry, and physical, space and sports medicine. Basic science specialties include absorptiometry, anatomy, anthropology, biochemistry, biomechanics, biophysics, genetics, histology, pathology, pharmacology, and cell and molecular biology. This article reviews our present general understanding of this new bone physiology and some of its clinical applications and implications. It must leave to other times, places, and people the resolution of questions about that new physiology, and to understand the many devils that should lie in its details. (Thompson D'Arcy, 1917). (+info)
Internal fixation on the lower cervical spine--biomechanics and clinical practice of procedures and implants.
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The decision to opt for a particular internal fixation procedure of a traumatized unstable lower cervical spine should be based on analysis and implementation of scientific and clinical data on the biomechanics of the intact, the unstable and the implant-fixed spine. The following recommendations for surgical stabilization of the lower cervical spine seem, therefore, to be justified. Firstly, the surgical procedure should be to bring about decompression, realignment, and stability. Secondly, the anterior approach should be the primary and preferred one. With regard to surgical and positioning technique, this access clearly involves fewer problems than the posterior approach; if required, unrestricted additional cord decompression can take place; implant fixation is technically simple, and the fusion is under direct compression, thus allowing optimal fusion healing. The awareness of instability and type of implant permits functional therapy, above all for the paraplegic patient. Thirdly, for traumatic conditions, posterior methods should be reserved for exceptional indications. The restriction to this approach is that the anterior column must be intact and a multi-segmental fixation must be used. Posterior fixation seems, therefore, to be more appropriate for degenerative, rheumatoid or tumorous instabilities than for traumatic instabilities. The cerclage wire technique depends on intact osseous posterior elements, while after laminectomy only implants fixed with screws can create safe stability. The disadvantages of the posterior access for the proprioception of the cervical muscles and the subjective symptoms of the patient are known and must be taken into account. Fourthly, combined techniques are indicated for highly unstable or particularly complex injuries. On the cervicothoracic junction, or in cases of Bechterew's disease, the decision is justifiably made in favor of this technique, which can be performed as a one-stage or two-stage operation. Finally, whenever possible, selection of the implant should take into account the foreseeable developments in diagnostic procedures, and therefore, in view of the modern imaging techniques likely to be used in any follow-up examinations required later, the implant chosen should be made of titanium. (+info)
Biomaterial-associated infection of gentamicin-loaded PMMA beads in orthopaedic revision surgery.
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In two-stage orthopaedic revision surgery, high local levels of antibiotics are achieved after removal of an infected prosthesis through temporary implantation of gentamicin-loaded beads. However, despite their antibiotic release, these beads act as a biomaterial surface to which bacteria preferentially adhere, grow and potentially develop antibiotic resistance. Gentamicin-loaded beads were retrieved from 20 patients with prosthesis-related infections. Excised tissue samples were taken for routine culture, while beads were analysed in an extensive laboratory procedure. Extensive culture procedures indicated the presence of bacteria on gentamicin-loaded beads in 18 of the 20 patients involved, while 12 of these 18 patients were considered free of infection by routine culture. Nineteen of 28 bacterial strains isolated were gentamicin resistant and cultures from three patients yielded highly gentamicin-resistant sub-populations. It is concluded that routine culture of excised tissues in orthopaedic revision surgery is inadequate to ascertain full eradication of infection, especially as infecting, antibiotic-resistant bacteria preferentially adhere to and grow on gentamicin-loaded beads. Extensive examination of the bead surfaces is proposed as a more reliable indication that infection has been eradicated. (+info)
Two family studies on congenital dislocation of the hip after early orthopaedic screening Hungary.
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Two family studies involving 1767 and 379 index patients in Budapest and Bekes county, respectively, were undertaken to examine the effect of early orthopaedic screening on the recurrence risk of congenital dislocation of the hip. About 14%, 2.1-2.3%,1.2-1.4%, and 4.7-6% of sibs, parents, uncles and aunts, and cousins, respectively, had congenital dislocation of the hip in these two surveys. The recurrence risks were eight-fold and four-fold higher in brothers and sisters, four times higher in parents, 2.5-fold higher in uncles and aunts, and 2.0-2.5 times higher in cousins, respectively, than in the general population. This family pattern seems to fit best with a model of polygenic-multifactorial inheritance. In earlier studies higher recurrence risks were found. These may be explained by the change of diagnosis due to early orthopaedic screening which may increase the possibility of over diagnosis and the treatment of mild cases which previously recovered spontaneously. (+info)
Chemonucleolysis: the state of the art.
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This review presents the history of chemonucleolysis, the techniques, indications, contraindications, and complications. Presenting an historical overview and comparison of success rates with surgical discectomy may provide a fresh understanding of the controversy surrounding chemonucleolysis and establish its efficacy in relation to more invasive treatments. A review of the literature from 1973 through 1998 for chemonucleolysis, open discectomy, and microdiscectomy provided published success rates for these procedures, and a mean rate with standard deviation was determined. In the experience and opinion of the authors, chemonucleolysis remains a viable alternative for patients who have exhausted all conservative means of treatment. Proper patient selection leads to success rates comparable to open discectomy and microdiscectomy. (+info)
Scattered radiation during fixation of hip fractures. Is distance alone enough protection?
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We measured the scattered radiation received by theatre staff, using high-sensitivity electronic personal dosimeters, during fixation of extracapsular fractures of the neck of the femur by dynamic hip screw. The dose received was correlated with that received by the patient, and the distance from the source of radiation. A scintillation detector and a water-filled model were used to define a map of the dose rate of scattered radiation in a standard operating theatre during surgery. Beyond two metres from the source of radiation, the scattered dose received was consistently low, while within the operating distance that received by staff was significant for both lateral and posteroanterior (PA) projections. The routine use of lead aprons outside the 2 m zone may be unnecessary. Within that zone it is recommended that lead aprons be worn and that thyroid shields are available for the surgeon and nursing assistants. (+info)
The utilization of synovial fluid analysis in the UK.
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OBJECTIVE: To ascertain what use is being made of synovial fluid analysis in the UK, who is carrying out polarized light microscopy (PLM), and what confidence clinicians have in the results. Subjects and methods. A postal survey was developed, piloted, adjusted and then posted to 535 people, 90% of whom were senior rheumatologists and 10% orthopaedic surgeons, whose names had been obtained from professional lists. RESULTS: Three hundred and eleven replies (59%) were obtained after 1 month. Analysis of the replies showed that only microbiological tests and PLM are used regularly, that these are used mainly for the diagnosis of acute arthritis, and that the majority of respondents would like data from these assays to be available within 24 h. The majority of the respondents (95%) had access to PLM and 80% said that clinicians should be able to use it. However, PLM is currently being undertaken by a variety of people: non-specialist technicians (34% of respondents), specialist technicians (35%) and clinicians (31%). Respondents were confident in microbiological assays but not in cell counts or PLM, unless they were undertaking it themselves. CONCLUSIONS: There is an urgent need for guidelines, standardization and education about the use of synovial fluid assays in the UK. (+info)
Reduced incidence of pressure ulcers in patients with hip fractures: a 2-year follow-up of quality indicators.
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OBJECTIVE: The aims of the present study were to (i) investigate the incidence of pressure ulcers in 1997 and 1999 among patients with hip fracture, (ii) study changes of nursing and treatment routines during the same period and (iii) to identify predictors of pressure ulcer development. DESIGN: The present comparative study was based partly on data collected in two prospective, randomized, controlled studies conducted in 1997 and 1999. SETTING: The study was carried out in the Accident & Emergency (A&E) Department and the Department of Orthopaedics at the University Hospital in Uppsala, Sweden. STUDY PARTICIPANTS: INCLUSION CRITERIA: patient with hip fracture, > or = 65 years, admitted without pressure ulcers. Forty-five patents were included in 1997 and 101 in 1999. INTERVENTIONS: Risk assessment, pressure ulcer grading, pressure-reducing mattress and educational programme. MAIN OUTCOME MEASURES: Incidence of pressure ulcers. RESULTS: There was a significant reduction of the overall incidence of pressure ulcers from 55% in 1997 to 29% in 1999. The nursing notes had become significantly more informative. Nursing and treatment routines for patients with hip fractures had changed both in the A&E Department and the orthopaedic ward through initiatives developed and implemented by pressure ulcer nurses. CONCLUSION: In the framework of a quality improvement project, where research activities were integrated with practice-based developmental work, the incidence of pressure ulcers was reduced significantly in patients with hip fractures. The best predictor of pressure ulcer development was increased age. (+info)