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Biomedical subjects

J D Blaha

Publications and source records attributed to J D Blaha.

34 records · Page 2Linked to original sources
PubMed1993

Audiometric thresholds in osteomyelitis patients treated with gentamicin-impregnated methylmethacrylate beads (Septopal).

Use of gentamicin-impregnated methylmethacrylate beads is a relatively new and effective method of treating osteomyelitis. Although previous studies have concluded that such therapy is associated with low systemic toxicity, no data are available relating the use of this treatment to ototoxicity and hearing loss. Audiometric thresholds from 28 cases of osteomyelitis treated by surgical debridement and long-term systemic antibiotics alone (14 subjects) or gentamicin-impregnated methylmethacrylate beads either alone or combined with systemic antibiotics (14 subjects) were analyzed. Results showed one permanent threshold shift in the gentamicin-impregnated methylmethacrylate beads group (8%) versus four permanent threshold shifts in the systemic antibiotics alone group (29%). Osteomyelitis patients treated with gentamicin-impregnated methylmethacrylate beads are at no more risk and are probably at less risk of experiencing ototoxicity than patients treated with conventional long-term systemic antibiotics.

Adult↗
PubMed1993

Comparison of the clinical efficacy and tolerance of gentamicin PMMA beads on surgical wire versus combined and systemic therapy for osteomyelitis.

These data do not prove a statistical superiority of conventional antibiotics or Septopal in the treatment of chronic osteomyelitis. This result, however, is complicated by the biased data set represented by the combined treatment. The data do suggest that cost of treatment is considerably less in patients who are treated with local antibiotics (i.e., Septopal) alone. The rate of adverse experiences was directly related to the use of parenteral antibiotics, with higher rates of adverse experiences in the conventional and combined treatment groups. Furthermore, the Cierny-Mader Physiologic Class had the best correlation with outcome, suggesting that host factors are probably of critical importance in inducing remission of chronic osteomyelitis. This protocol was not designed to test the role of debridement in the treatment of osteomyelitis: it was assumed that debridement would be the same in both groups. It is the investigators' strong opinion, however, that adequacy of debridement was an important determinant in quiescence or recurrence in the study patients. Similarly, there was no strict control for adequacy of soft-tissue coverage provided by local or distant tissue transfer. Again, the investigators believe that adequacy, including viability and durability, of soft-tissue covering was an important determinant for the end result in these patients. Other covariants such as smoking, history, nutritional status, and other measures of general health will be added to this model when data are available. This analysis will allow definition of the appropriate clinical situations in which use of Septopal alone or combined with parenteral antibiotic is indicated.

Anti-Bacterial Agents↗
PubMed1993

A comparison of gentamicin-impregnated polymethylmethacrylate bead implantation to conventional parenteral antibiotic therapy in infected total hip and knee arthroplasty.

A multicenter study of infected total knee and total hip arthroplasties was conducted from 1985 until 1990. Twenty-eight patients (22 total hip arthroplasties and six total knee arthroplasties) who had periprosthetic infections were treated according to a prospective, randomized protocol. After initial debridement for their infections, patients were randomized into one of the two following groups: Group I, debridement and the implantation of gentamicin-polymethylmethacrylate (PMMA) beads; and Group 2, debridement and conventional parenteral systemic antibiotic therapy. After initial treatment, the patients were then scheduled for a delayed reconstruction total joint arthroplasty. Of the 28 patients, 25 subsequently had delayed total arthroplasty, and if acrylic bone cement was used for fixation at the time of reimplantation, antibiotics were not added to the cement. The average follow-up period was three years (range, six months to 5.6 years). Infection recurred in two patients treated by debridement and the implantation of gentamicin-PMMA beads (15%) and in four patients treated with debridement and conventional systemic antibiotic therapy (30%). All recurrences occurred in patients who had infected total hip arthroplasties; none occurred in patients with total knee arthroplasties. The conditions that were common in patients with recurrent infection were (1) multiple previous surgeries, (2) host compromise and malnutrition, (3) extensive infection, and (4) inadequate debridement. The recurrence of infection was not statistically significantly more common in either treatment group. The outcome of treatment in patients with infected total joint arthroplasties using debridement, gentamicin-PMMA bead implantation,and a two-stage delayed reconstruction was similar to that of patients treated with debridement combined with conventional parenteral systemic arthroplasty and two-stage reconstruction.

Adult↗
PubMed1991

In vivo measurements of relative motion between an uncemented femoral total hip component and the femur by roentgen stereophotogrammetric analysis.

Roentgen stereophotogrammetric analysis (RSA) was used to study rotation and subsidence of an uncemented polyethylene-coated femoral component for total hip arthroplasty in ten patients younger than 55 years of age. Three years postoperatively, the total subsidence averaged 2.44 mm and the internal rotation was 7.4 degrees. The rate of subsidence decreased between the observation periods, whereas the rate of rotation, after an initial significant decrease, became almost constant. One patient, who was a clinical failure and required revision arthroplasty, had a significantly higher rate of migration after six months. The pattern of subsidence in the absence of pain might be the normal reaction of bone to an uncemented prosthesis, but the continuing rotation suggests the potential for failure of the arthroplasty. The type of analysis made possible in RSA may allow early prediction of the success of arthroplasties and significantly speed the design cycle for arthroplasty components.

Adult↗
PubMed1991

Patients' recall of preoperative instruction for informed consent for an operation.

Thirty-eight consecutive patients who were admitted to the hospital for total joint replacement were studied to determine their understanding of the elements of informed consent at the time when they signed the consent document before the operation and their recall of those elements six months after the operation. All patients received instruction from the same patient-educator before the operation. Each patient was asked to respond verbally to a questionnaire about the preoperative instruction. If a question was not answered correctly, tutoring was given until the patient gave the correct response. The consent document was not presented for signature until the patient could answer all questions correctly. In an interview six months after the operation, thirty-six of the thirty-eight patients were asked the same questions that they had answered before the operation. The recall of risks and benefits six months after the operation was compared with the understanding of risks and benefits that had been demonstrated before the operation by both the verbal questioning and the signed consent document. At six months, the number of patients who recalled the risks ranged from nine (25 per cent) who remembered the risk of infection to only one who remembered the risk of damage to a nerve or artery. More patients recalled the potential benefits: eight (22 per cent) for relief of pain and improved function and five (16 per cent) for improved motion.

Adult↗
PubMed1989

The effects of altered strain environments on bone tissue kinetics.

This study defines the alteration in bone tissue kinetics responsible for the "adaptive remodeling" response to altered strain environments. Adult beagle dogs were separated into three experimental groups: ulnar osteotomy, ulnar osteotomy with fracture fixation plate spanning the gap and sham surgery. Four sets of double fluorochrome labels were administered. Prior to sacrifice at 1, 3, and 6 months, strains were measured through rosette strain gages on the cranial and caudal surfaces of the intact radius. Histomorphometric analysis indicated that the increased bone mass in response to elevated strain results from increased activation frequency of modeling with more sites undergoing formation processes than resorption processes on periosteal and endocortical surfaces. Increased remodeling activation did not lead to increased bone mass. There was no evidence that elevated strain changes the individual vigor of osteoclasts or osteoblasts, or that the sigma period was altered by elevated strain.

Adaptation, Physiological↗
PubMed1989

Skeletal change in response to altered strain environments: is woven bone a response to elevated strain?

Studies demonstrate that geometric changes in bone architecture in response to altered mechanical strain occur through the formation of woven bone. The goal of this study was to test the hypothesis that these changes are partly the result of surgical manipulation rather than a true adaptive response to altered strain. Beagle dogs were subjected to either an ulnar osteotomy, an osteotomy with plate fixation, or sham operation. Strains on the radius were measured just prior to sacrifice 1, 3 or 6 months after surgery. Our results support the idea that woven bone can be a normal response to an abnormal strain environment if the mechanical challenge is intense enough; that elevated mechanical strains can cause the endocortical bone envelope to revert to a state of net formation; and that "adaptive remodeling" in adults in response to a change in mechanical strain may be a special case of modeling in which resorption is not required prior to formation at a particular skeletal site.

Adaptation, Physiological↗
PubMed1988

Characterization of link protein(s) from human intervertebral-disc tissues.

Proteoglycan aggregates (A1) were prepared from the anulus fibrosus, nucleus pulposus and cartilage-endplate tissues of postnatal (0-6-month-old)-and young-adult (20-30-year-old)-human intervertebral discs. The A1 fractions from young-adult disc contained a greater proportion of non-aggregating proteoglycans than did postnatal tissues. After dissociative CsCl-density-gradient fractionation of the A1, more than 90% of the uronic acid was found in the postnatal A1D1, whereas only 60-80% of the hexuronate was present in the A1D1 isolated from young-adult disc tissues. These results indicated that more lower-buoyant-density proteoglycans occur in the young-adult disc. Link-protein-rich fractions (A1D3) were subjected to SDS/polyacrylamide-gel electrophoresis and immunolocation analyses using monoclonal antibodies specific for epitopes on link protein or proteoglycan. Under non-reducing conditions, the major link protein present in postnatal disc tissues was link protein 1. By contrast, all three link proteins (1, 2 and 3) were detected in young-adult tissues, with the smaller link protein 3 predominating. Analyses of the A1D3 fractions under reducing conditions also indicated the presence of link-protein-degradation peptides (Mr approx. 26,000) from young-adult disc tissues, but not from postnatal tissues. Sequential Sepharose CL-6B and Sephacryl S-300 chromatography in 4 M-guanidinium chloride was employed to separate the link proteins of the A1D3 fraction from protein-rich proteoglycan. Immunolocation analyses indicated that postnatal samples contained no detectable contaminating proteoglycan fragments. However, young-adult link-protein preparations could not be separated from hyaluronic acid-binding region and other proteoglycan fragments by means of these chromatographic procedures. The studies indicate that, compared with hyaline articular cartilage, degraded link protein and proteoglycan accumulate at an early age in young-adult disc tissues. These partially degraded proteoglycan aggregate components may significantly alter the biomechanical properties of disc tissues.

Adult↗
PubMed1983

Alignment in total knee arthroplasty. Correlated biomechanical and clinical observations.

The initial experience with the Freeman-Swanson (ICLH) total knee arthroplasty (1971-1975) led to changes of tibial component size, alignment, instruments, and surgical technique in 1975. Certain patients in this initial series, however, have shown excellent long-term (5 1/2-9 years) results. In patients with overall alignment between 1 degrees and 13 degrees valgus, the success rate was 89%. In patients with knees aligned between neutral and 8 degrees varus, the success rate was only 14%. This startling difference in long-term results was investigated by using eccentric loading tests to simulate varus and valgus malalignment. Knee arthroplasties failed in eccentric loading at very low loads. Failure by lift-off of the unloaded side occurred at 9%-18% and failure of bone due to compression on the loaded side occurred at 34%-51% of the load at failure under ideal uniform loading conditions. Thus, both the long-term clinical study and the laboratory analysis demonstrate the importance of proper overall alignment in total knee arthroplasty.

Biomechanical Phenomena↗
PubMed1982

Cementless fixation of the tibial component for the ICLH knee.

The use of polymethylmethacrylate bone cement in joint replacement surgery is not without drawbacks. Certain hazards have been appreciated and the bone cement interface may not be as stable in the long run as was once felt. This paper reports the results in 52 knees which were replaced using the uncemented ICLH (Imperial College/London Hospital) tibial component; the average follow up was two years (range six months to four years). The results were compiled with regard to pain as well as clinical examination and X-ray evaluation. The results were comparable to those achieved in knees replaced using bone cement. Roentgenographic evaluation revealed no evidence of loosening nor sinkage of any of these prostheses. Considerations in the development of a knee prosthesis to be utilized without bone cement and the operative technique employed to implant such a prosthesis are presented. The merits of such a system are discussed.

Adult↗