Use In Orthopaedic Surgery Research Articles

Rehabilitation of spasticity and related problems in childhood cerebral palsy.

Spasticity is one part of the upper motor neuron syndrome, but it is a widespread problem in cerebral palsy; it is debilitating, affects function and can lead to musculoskeletal complications. Significant advances have occurred in antispasticity management (and related musculoskeletal problems) in children with cerebral palsy during the past 5-10 years. Botulinum toxin A has been the most outstanding treatment advance; it is relatively long-lasting, easy to administer, reversible, has a favourable side-effect profile and is highly useful for focal spasticity. There is an emerging role for intrathecal baclofen in Australia. Despite being available and practised in North America for years, selective dorsal rhizotomy has not been popular in Australia. The use of orthopaedic surgery has significantly altered in recent years. There is still a place for oral drug treatment, including some newer agents and the potential for combination treatment with other modalities. The role of physical therapy in defining disability, assessing function, undertaking biomechanical assessment and providing mobility aids/casting/orthoses and motor training/stretching exercises is critical for the success of medical and surgical interventions. From an Australian perspective, the purpose of the present review is to provide a critical review of therapies available for spasticity associated with childhood cerebral palsy.

Effects of glass ionomer cements on bone tissue.

In vivo biocompatibility of glass ionomer cements (GICs) was evaluated for use in orthopaedic surgery using a rat model and compared with conventional bone cement, Polymethyl methacrylate, PMMA. The unset GICs and PMMA were inserted into the marrow cavities of rat femora and retained in situ for various periods of time. The PMMA bone cement showed complete biocompatibility with no interference with reparative bone. The conventional GIC with smaller glass particles and lower powder/liquid ratio showed an initial minor toxic effect on rat bone tissue with later disturbance of adjacent bone formation. The conventional GIC with larger-size glass particles and higher powder/liquid ratio and resin-modified GIC showed more severe toxic effect on rat tissue with the resin-modified GIC affecting the rat bone tissue later. The causes of toxicity associated with the conventional GIC with larger glass particles and higher powder/liquid ration and the resin-modified GIC are thought to be related with the unreacted acid component of both materials and longer ongoing metallic ion release.

The potential role of new therapies in deep-vein thrombosis prophylaxis.

The value of prophylaxis against venous thromboembolism (VTE) is increasingly accepted in most surgical specialties, although the potential reduction in fatal pulmonary embolism has recently been questioned. The burden of VTE in hospital patients nevertheless remains high, partly attributable to underuse of thromboprophylaxis and partly attributable to occurrence of VTE in high-risk patients because recommended antithrombotic therapies fail to provide full protection. Improved physician education has been shown to increase the application of antithrombotic measures, and research efforts are focused on developing novel antithrombotic agents with greater efficacy and safety in clinical use. Several novel indirect and direct thrombin inhibitors have been investigated. The heparinoid danaparoid has shown superiority over unfractionated heparin in several indications, but only the recombinant hirudin, desirudin, has exhibited greater efficacy than low-molecular-weight heparin (LMWH) in thromboprophylaxis for patients undergoing elective hip-replacement surgery, without increasing the risk of bleeding. Three large-scale clinical trials have shown desirudin to be the most effective thromboprophylactic agent currently available in elective hip-replacement surgery; this agent has now been licensed for use in orthopedic surgery. Research is ongoing into the feasibility of still more effective and convenient therapies, such as oral antithrombins.

The potential role of new therapies in deep-vein thrombosis prophylaxis

The value of prophylaxis against venous thromboembolism (VTE) is increasingly accepted in most surgical specialties, although the potential reduction in fatal pulmonary embolism has recently been questioned. The burden of VTE in hospital patients nevertheless remains high, partly attributable to underuse of thrombopro-phylaxis and partly attributable to occurrence of VTE in high-risk patients because recommended antithrom-botic therapies fail to provide full protection. Improved physician education has been shown to increase the application of antithrombotic measures, and research efforts are focused on developing novel antithrombotic agents with greater efficacy and safety in clinical use. Several novel indirect and direct thrombin inhibitors have been investigated. The heparinoid danaparoid has shown superiority over unfractionated heparin in several indications, but only the recombinant hirudin, desirudin, has exhibited greater efficacy than low-molecular-weight heparin (LMWH) in thromboprophylaxis for patients undergoing elective hip-replacement surgery, without increasing the risk of bleeding. Three large-scale clinical trials have shown desirudin to be the most effective thromboprophylactic agent currently available in elective hip-replacement surgery; this agent has now been licensed for use in orthopedic surgery. Research is ongoing into the feasibility of still more effective and convenient therapies, such as oral antithrombins.

Comparison of the material properties of PMMA and glass-ionomer based cements for use in orthopaedic surgery.

The intrinsic benefits of low exotherm and bioactivity have generated interest in utilizing glass-ionomer cements (GIC) as a bone cement replacement in orthopaedic surgery. This paper is concerned with evaluating the mechanical properties of compressive strength, flexural strength, and fracture toughness for two traditional GICs, one resin-modified GIC (an experimental bone cement) and two polymethylmethacrylate (PMMA) cement systems. To determine the suitability of a GIC system for use in the clinical orthopaedic setting, the additional characteristics of setting exotherm and setting time have also been evaluated. The characterization of these two vastly different cement systems has raised some concern as to the applicability of using the current orthopaedic standards for the testing of GIC systems. In particular, issues relating to the strain rate dependence of PMMA cement and the exothermic basis for determining setting time are not applicable as these factors are not characteristic of GIC systems. Whilst the intrinsic benefits of current GIC systems are well understood and generally accepted, this study has shown their intrinsic mechanical properties to be inferior to current PMMA cements. Improvement in the mechanical properties of traditional GICs have been achieved with the addition of a resin component (HEMA).

The Effects, Risks, and Guidelines for Radiation Use in Orthopaedic Surgery

Radiation is used during orthopaedic surgery in more than 15 million studies performed yearly. The biologic effects of radiation have been shown to inhibit mitosis by producing irrepairable deoxyribonucleic acid double strand breaks or create structural changes by damaging the nucleus, thereby producing potential genetic transmissions. Although human cells are thought to be resistant to malignant change and no studies have shown toxic effects resulting from long-term exposure to low-dose radiation, risks still are assumed. To decrease all risks, radiographic units should undergo periodic calibration, surgeons should wear protective devices, increase their working distance from the x-ray beam, and limit their duration of radiation exposure by making certain that they follow the guidelines set forth by the National Council for Radiation Protection and Measurement.

Use of bone-bonding hydrogel copolymers in bone: An in vitro and in vivo study of expanding PEO-PBT copolymers in goat femora

Polyactive® [polyethylene oxide–polybuthylene terephtalate (PEO-PBT)] refers to a group of copolymers with bone-bonding properties. In reference to these properties, PEO-PBT copolymers are currently being investigated for their possible use in orthopedic surgery and dentristry. PEO-PBT copolymers exhibit hydrogel behavior. When swelling in fluid is prohibited by mechanical confinement, the copolymers exert a swelling pressure on surrounding structures. In the first part of this study, these swelling pressures were measured in vitro. Polymers with different ratios of PEO-PBT exerted a swelling pressure of more than 2 MPa when tested in fluid between the crossheads of a Hounsfield testbench. In the second part of the study, the biocompatibility of PEO-PBT 55-45 and the effect of continuous intramedullary pressure of these copolymers on bone was investigated. Large cylinders of dry PEO-PBT 55-45 were implanted with a tight fit in the distal part of goat femora. Preswollen cylinders of PEO-PBT implanted in the opposite femur served as a control. Although it was assumed that the pressure of dry PEO-PBT on the bone would reach more than 2 MPa with press-fit insertion, no immediate hazardous effects of the expanding polymer were noticed within the first days postoperatively. The goats were sacrificed after 3, 9, and 25 weeks. Histological examination showed good implant–bone contact at different follow-up times in the distal femora with the dry implanted implants. The femora in which the preswollen cylinders had been implanted showed a thin layer of soft tissue between the PEO-PBT implant and bone. The swelling pressure exerted by dry press-fit implanted PEO-PBT implants is an important factor in creating a strong interface bond between PEO-PBT and bone. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 49, 312–318, 2000.

Use of bone-bonding hydrogel copolymers in bone: an in vitro and in vivo study of expanding PEO-PBT copolymers in goat femora.

Polyactive(R) [polyethylene oxide-polybuthylene terephtalate (PEO-PBT)] refers to a group of copolymers with bone-bonding properties. In reference to these properties, PEO-PBT copolymers are currently being investigated for their possible use in orthopedic surgery and dentistry. PEO-PBT copolymers exhibit hydrogel behavior. When swelling in fluid is prohibited by mechanical confinement, the copolymers exert a swelling pressure on surrounding structures. In the first part of this study, these swelling pressures were measured in vitro. Polymers with different ratios of PEO-PBT exerted a swelling pressure of more than 2 MPa when tested in fluid between the cross-heads of a Hounsfield test-bench. In the second part of the study, the biocompatibility of PEO-PBT 55-45 and the effect of continuous intramedullary pressure of these copolymers on bone was investigated. Large cylinders of dry PEO-PBT 55-45 were implanted with a tight fit in the distal part of goat femora. Preswollen cylinders of PEO-PBT implanted in the opposite femur served as a control. Although it was assumed that the pressure of dry PEO-PBT on the bone would reach more than 2 MPa with press-fit insertion, no immediate hazardous effects of the expanding polymer were noticed within the first days postoperatively. The goats were sacrificed after 3, 9, and 25 weeks. Histological examination showed good implant-bone contact at different follow-up times in the distal femora with the dry implanted implants. The femora in which the preswollen cylinders had been implanted showed a thin layer of soft tissue between the PEO-PBT implant and bone. The swelling pressure exerted by dry press-fit implanted PEO-PBT implants is an important factor in creating a strong interface bond between PEO-PBT and bone.

Ionogran in revision arthroplasty.

Glass ionomer cement (Ionocem) was developed for use in bone surgery and is reported to be notably biocompatible. Between 1991 and 1994 we performed revision operations for aseptic loosening of arthroplasties of the hip on 45 patients using this material in its granulate form (Ionogran) mixed with homologous bone as a bone substitute. Of these 45 patients, 42 were followed up for a mean of 42 months. Early reloosening of the acetabular component has occurred in ten after a mean of 30 months. Histological examination showed large deposits of aluminium in the adjacent connective tissue and bone. Osteoblastic function and bone mineralisation were clearly inhibited. The serum levels of aluminium were also increased. The toxic damage at the bone interface caused by high local levels of aluminium must be seen as an important factor in the high rate of early reloosening. Our findings cast doubt on the biocompatibility of this material and we do not recommend continuation of its further use in orthopaedic surgery.

Ionogran in revision arthroplasty

Glass ionomer cement (Ionocem) was developed for use in bone surgery and is reported to be notably biocompatible. Between 1991 and 1994 we performed revision operations for aseptic loosening of arthroplasties of the hip on 45 patients using this material in its granulate form (Ionogran) mixed with homologous bone as a bone substitute. Of these 45 patients, 42 were followed up for a mean of 42 months. Early reloosening of the acetabular component has occurred in ten after a mean of 30 months. Histological examination showed large deposits of aluminium in the adjacent connective tissue and bone. Osteoblastic function and bone mineralisation were clearly inhibited. The serum levels of aluminium were also increased. The toxic damage at the bone interface caused by high local levels of aluminium must be seen as an important factor in the high rate of early reloosening. Our findings cast doubt on the biocompatibility of this material and we do not recommend continuation of its further use in orthopaedic surgery.

The utility and prediction of allogeneic blood transfusion use in orthopedic surgery

It is possible to predict the likelihood of postoperative blood transfusion using patient variables. The information could be used to target the high-risk group for intervention(s) that would subsequently reduce the risk of exposure to allogeneic blood. The cost of several of the alternatives to allogeneic blood precludes their use on all surgical patients, and hence the need to identify those patients who are most likely to benefit from such therapy. Further research is needed to assess the impact of predictive models on the use of allogeneic blood and costs. Research is also needed to clarify the impact of blood transfusion on perioperative morbidity and mortality, in patients with and without heart disease. If such an association does indeed exist, then an optimal hemoglobin or transfusion threshold is needed to guide clinicians in caring for their patients.

Growth factor stimulation of bone healing

Bone tissue has been shown to contain numerous cell-to-cell signalling peptides called growth factors. These growth factors are thought to have important regulating effects for bone remodeling and bone healing, due to their potent effects on bone cell metabolism. In vivo studies over the last half decade have demonstrated that growth factors candidates for future clinical use in orthopedic surgery. In numerous clinical situations enhanced bone formation and bone healing could lead to improved results of surgical procedures. This thesis describes the most important bone growth factors and their actions in vitro and in vivo. In vitro investigations of growth factor effects on osteoblast chemotaxis and metabolism are described as well as in vivo studies with growth factor stimulation of fracture healing and bone healing to prosthetic-like implants. In vitro results: Several growth factors exhibited chemotactic effects towards human osteoblasts. TGF-beta 1 and PDGF-BB had the strongest chemotactic effects, whereas PDGF-AA, IGF-1, and IGF-2 had less but significant chemotactic effects towards human osteoblasts. TGF-beta 1 exhibited the highest chemotactic potency with maximal activity at 100 pg/mL, whereas the other growth factors had maximal effects at 10-100 ng/mL. BMP-2 was found to have chemotactic effects toward human osteoblasts, human bone marrow osteoprogenitor cells, and U2-OS osteosarcoma cells. BMP-4 and BMP-6 were without any chemotactic effects towards these celltypes. Human bone marrow osteoprogenitor cells were the most responsive celltype to BMP-2 stimulation. Growth factor combinations resulted in synergic stimulative effects on different metabolic functions on human osteoblasts. Combinations with TGF-beta 1 and PDGF-BB strongly stimulated proliferation and chemotaxis. Combinations with TGF-beta 1, PDGF-BB and BMP-2 strongly stimulated an osteoblast differentiation parameter (alkaline phosphatase activity). The different growth factor combinations had no effect on collagen synthesis in human osteoblasts. In vivo results: Continuous application of 1 and 10 micrograms natural TGF-beta to a plated tibial osteotomy in rabbits increased mechanical bending strength and callus formation at 6 weeks observation. Diaphyseal cortical bone remodeling was not affected by the local growth factor application. In a dog model with unloaded implants surrounded by a gap, 0.3 microgram rhTGF-beta 1 adsorbed to gritblasted tricalcium phosphate coated implants, was able to enhance mechanical fixation, bone ingrowth and gap bone formation. 3.0 micrograms rhTGF-beta 1 had less but significant stimulative effect. In a weight-loaded model, 0.3 microgram rhTGF-beta 1, adsorbed to gritblasted tricalcium phosphate coated implants, was able to enhance bone ingrowth, without enhancement of mechanical fixation. In the unloaded model, 0.3 microgram rhTGF-beta 1, adsorbed to gritblasted hydroxyapatite coated implants, was able to enhance bone ingrowth, without enhancement of mechanical fixation. 3.0 micrograms rhTGF-beta 1 had no stimulative effects. The establishment of a biological implant fixation concept with growth factor absorbed to ceramic coatings of implants was successful. These data are promising for a possible future clinical usage of growth factors, especially for enhancement of bone healing to cementless prosthetic components.

Growth factors: possible new clinical tools. A review.

Bone tissue contains numerous cell-to-cell signaling peptides called growth factors with potent effects on bone cell metabolism. In vivo studies over the last 5 years have demonstrated that growth factors can stimulate bone formation and bone healing and these results have made them candidates for use in orthopedic surgery. In numerous clinical conditions enhanced bone formation and bone healing could improve the results of surgery; clinical trials using growth factors to stimulate bone formation in spinal surgery, and to stimulate healing of bone defects, have been initiated. Growth factors for clinical use will become commercially available in the near future. This review describes the main growth factors and their actions in vitro and in vivo in relation to bone tissue and bone healing. Possible areas for clinical use are also discussed.

An Intelligent Degradable Polymer Composite Which Closely Matches Bone

Polyhydroxybutyrate (PHB) and its copolymers with polyhydroxyvalerate (PHV) are a range of slowly degrading polyesters with potential for use in orthopaedic surgery. The polymer degradation profile is unpredictable and thus a composite of PHB/7 % PHV and a completely soluble phosphate based glass reinforcement was compounded. This glass may be produced with a defined solubility rate and this was shown to control the overall degradation of the PHB/glass composite, in terms of both mass loss and change in mechanical properties. The piezoelectric properties of the composite were examined and the strain generated potentials were seen to be of a similar order of magnitude to that of bone. In vivo studies were carried out and as with the in vitro work, the reaction could be closely correlated with the composite solubility. Furthermore, tissue reaction at various stages could be closely linked to the composite solubility.

Development of a degradable composite for orthopaedic use: mechanical evaluation of an hydroxyapatite-polyhydroxybutyrate composite material

This study evaluates the mechanical properties of a composite material comprising polyhydroxybutyrate with hydroxyapatite added in proportions varying from 0 to 50%. Among the three methods of production, injection moulding was found to result in the most satisfactory mechanical properties. The tensile and compressive strength and the modulus of elasticity of composite produced in this way fell within the range for fresh human bone from different anatomical sites. With the additional advantages of biocompatability, biodegradability and the potential for piezoelectric stimulation of new local bone formation, it was concluded that the injection-moulded composite material has considerable potential for use in orthopaedic surgery, both as a material to construct certain orthopaedic implants and as an alternative to corticocancellous bone graft.

Holmium laser surgery.

This relatively new form of laser energy, with its powerful and precise ability to ablate the dense tissues of the musculoskeletal system as well as its transmissibility in fiberoptic cables and a fluid medium, makes this an ideal tool for use in orthopedic surgery. Its importance as a new orthopedic modality may well lie in its unique ability to gain access to small articular compartments while providing superior homeostatic control, thereby decreasing postoperative morbidity. While not yet in widespread use, its popularity is rapidly spreading and research into a variety of new applications is growing steadily.

History of Soft-Tissue Allografts in Orthopedics

Experimentation with soft-tissue allografts has been reported for over 100 years. Gluck described the successful transplantation of an Achilles tendon in a chicken in 1881. Subsequent animal work with tendon and fascia transplantation continued in the early 1900s. The first attempt at preservation prior to implantation was reported in 1918. A case of human tendon allografting was reported in 1923 involving the use of an entire patella with its attached tendons. Successful fascial allograft use in humans was noted in 1927. A large amount of experimental and clinical work in flexor tendon replacement of the hand was performed in the 1960s and 1970s. However, such application was curtailed in the 1980s. Allograft tissue for anterior cruciate ligament reconstruction has seen an enormous amount of use in the last 10 years. Numerous reports of ACL allograft selection, processing and preservation, mechanical properties, rejection phenomenon, and clinical results are in the literature. Early use has been encouraging, although a possible trend toward late failure is noted. Meniscal allografts have also been used and have shown limited clinical success. The use of allograft tissue in other joints has also been reported. The concomitant rise in allograft bone and cartilage transplantation is noted, along with the development of tissue banks. Although many questions remain unanswered with respect to soft-tissue allografts, there is clearly a role for their continued use in orthopedic surgery.

Evaluation of wear in an all-polymer total knee replacement. Part 2: Clinical evaluation of wear in a polyethylene on polyacetal total knee

In an effort to improve the long-term result of total joint replacement arthroplasty, we have investigated the use of a polymer-on-polymer articular replacement arthroplasty. Because of their known biocompatibility and previous use in orthopedic surgery, polyethylene and polyacetal (copolymer, Hoechst) were selected. Polyethylene served in its usual role as the concave member of the articulation; polyacetal formed the convex member. Formal wear testing using a multi-channel hip simulator demonstrated superior wear characteristics of the polymer-on-polymer configuration compared to a conventional chrome-cobalt versus polymer (polyethylene) configuration. A clinical series of relatively high-activity patients having a minimum five-year follow-up ( N = 26) showed no specific unfavorable reaction to this material combination in a total knee replacement. Given certain potential advantages of polymeric materials, as well as some theoretical disadvantages of metallic materials, a polymer-on-polymer design for a large joint replacement may have some merit.

Polymethylmethacrylate: a Review of the Implications and Complications of its Use in Orthopaedic Surgery

Polymethylmethacrylate has application in the fixation of endoprostheses and void-filling in reconstructive and neurological surgery in both veterinary and human surgery. It also has extensive dental and ophthalmic applications. Literature detailing the nature of the bone/cement interface is reviewed along with the local effect of polymethylmethacrylate on bone and cartilage. The repercussions of the cellular effects of polymethylmethacrylate on the development of loosening are discussed. The immunosuppressive effects of polymethylmethacrylate to the patient are outlined. A review of the cardiovascular, pulmonary and hepatic toxicity problems of polymethylmethacrylate is included. Contact sensitisation of the user is briefly discussed in conclusion.

Acute Care to Prevent Back Disability

Efforts to curb back problems through preemployment screening, safety measures, and educational programs have had little effect on this most expensive musculoskeletal malady. Present knowledge raises doubts about the possibility of preventing back pain. However, recent scientific investigations indicate that chronic back pain disability, which accounts for 80% of the costs for back problems, can be prevented. In Gothenburg, Sweden, the collective use of proven treatment methods during the acute stage of back symptoms markedly reduced the period of time patients were disabled from back problems. Effective early intervention centers around: teaching patients about back care, including how to control symptoms through improved body mechanics; applying these educational principles, specifically to the patient's livelihood; avoiding the debilitation that results from overusing bed rest and medication; recommendations to increase cardiovascular fitness; and the judicious use of orthopedic surgery. This approach targets the few patients who tend to be disabled the longest, suffer the most, and become the most costly to society.