Surface properties of Indonesian-made narrow dynamic compression plates.

The enormous need of orthopaedic (surgical) implants such as osteosynthesis plates is difficult to be fulfilled in developing countries commonly rely on imported ones. One of the alternatives is utilization of local resources, but only after they have been proven safe to use, to overcome this problem. Surface properties are some of the determining factors of safety for those implants. We have succeeded in developing prototype of osteosynthesis plate and the results indicate that Indonesian-made plates need improvement with regards to the surface quality of physical characterization.

Evaluation of measures to decrease intra-operative bacterial contamination in orthopaedic implant surgery.

The aim of this study was to evaluate whether behavioural and systemic measures will decrease intra-operative contamination during total hip or knee replacements. The influence of these measures on subsequent prolonged wound discharge, superficial surgical site infection and deep periprosthetic infection was also investigated during an 18-month follow-up period. Four swabs were taken from instruments at the beginning and end of the procedure for 207 procedures. Removed bone material (acetabulum and femur in case of the hip joint; femur and tibia in case of the knee joint) was also tested for contamination. Initially, 70 operations performed under original control conditions were included, after which the first behavioural measure was introduced (i.e. better use of the plenum). Cultures were taken during 67 operations using better use of the plenum (Group 1), followed by disciplinary measures and the installation of a new laminar flow system. Seventy operations were monitored after this second intervention (Group 2). The control group showed intra-operative contamination in 32.9% (23/70) of cases, Group 1 showed contamination in 34.3% (23/67) of cases and Group 2 showed contamination in 8.6% (6/70) of cases. Prolonged wound discharge and superficial surgical site infection decreased significantly in Group 2, as did the incidence of deep periprosthetic infection; however, the latter did not reach statistical significance. This study shows that the combination of systemic and behavioural changes in an operating room significantly decreases the incidence of intra-operative bacterial contamination, subsequent prolonged wound discharge and superficial surgical site infection. After 18 months of follow-up, there was also a decrease in deep periprosthetic infection.

Digital correction of magnification in pelvic x rays for preoperative planning of hip joint replacements: theoretical development and clinical results of a new protocol.

The introduction of digital radiological facilities leads to the necessity of digital preoperative planning, which is an essential part of joint replacement surgery. To avoid errors in the preparation and execution of hip surgery, reliable correction of the magnification of the projected hip is a prerequisite. So far, no validated method exists to accomplish this. We present validated geometrical models of the x-ray projection of spheres, relevant for the calibration procedure to correct for the radiographic magnification. With help of these models a new calibration protocol was developed. The validity and precision of this procedure was determined in clinical practice. Magnification factors could be predicted with a maximal margin of error of 1.5%. The new calibration protocol is valid and reliable. The clinical tests revealed that correction of magnification has a 95% margin of error of -3% to +3%. Future research might clarify if a strict calibration protocol, as presented in this study, results in more accurate preoperative planning of hip joint replacements.

Bacterial survival in the interfacial gap in gentamicin-loaded acrylic bone cements.

Clinical experience indicates the beneficial effects of antibiotic-loaded bone cement. Although in vitro studies have shown the formation of a biofilm on its surface they have not considered the gap between the cement and the bone. We have investigated bacterial survival in that gap. Samples with gaps 200 microm wide were made of different bone cements. These were stored dry ('pre-elution') or submersed in phosphate-buffered saline to simulate the initial release of gentamicin ('post-elution'). The gaps were subsequently inoculated with bacteria, which had been isolated from infected orthopaedic prostheses and assessed for their sensitivity to gentamicin. Bacterial survival was measured 24 hours after inoculation. All the strains survived in plain cements. In the pre-elution gentamicin-loaded cements only the most gentamicin-resistant strain, CN5115, survived, but in post-elution samples more strains did so, depending on the cement tested. Although high concentrations of gentamicin were demonstrated in the gaps only the gentamicin-sensitive strains were killed. This could explain the increased prevalence of gentamicin-resistant infections which are seen clinically.

Antibiotic use after cefuroxime prophylaxis in hip and knee joint replacement.

The amount of additional antibiotics measured by defined daily dose (DDD) methods after 2651 hip and 362 knee replacements was assessed after prophylaxis with one or three doses (1502/1511 patients) of cefuroxime. No differences were observed between the two regimens with respect to total amount, type, indication, and duration of additional antibiotics. The incidence of joint sepsis did not differ significantly between the two trial arms, but the sample was too small for definite conclusions. There were 11.4 DDD/100 bed days of additional antibiotics used in 21% of patients after hip replacement and 15.7 DDD/100 bed days in 31% after knee replacement. For wound problems, 3.8 and 6.9 DDD/100 bed days were given in the hip- and knee-replacement groups. For distant infection, 6.5 DDD/100 bed days was administered in both groups. Duration of therapy varied only in relation to indication. Prescribed were penicillins (43% to 50%), sulfonamides (18%), cephalosporins (10% to 16%), and nitrofurantoin (8% to 13%); drug use was related to the type of infection.

Nuclear arthrography: combined scintigraphic and radiographic procedure for diagnosis of total hip prosthesis loosening.

UNLABELLED: Radiographic arthrography and bone scintigraphy are common diagnostic procedures used for evaluating total hip prostheses. In this study, both techniques are combined, and nuclear contrast imaging (nuclear arthrography) is added. The efficacy of the procedures is evaluated. METHODS: After intravenous injection of 99mTc-methylene diphosphonate (MDP), standard radiographic arthrography was performed in 105 patients (107 prostheses). The radiographic contrast medium was mixed with insoluble 111In-colloid (5 MBq/20 ml). After completion of the radiographic arthrography, nuclear arthrography was performed, and multiple-view dualisotope images (111In, 247-keV peak only) were recorded. Images were interpreted by superposition of the 111In image and the corresponding 99mTc-MDP image, the latter serving as a landmark for the position of the prosthesis and osseous structures. Findings at surgery were used as the gold standard. RESULTS: In both cemented and uncemented acetabular and femoral components, nuclear arthrography performed better than or equal to radiographic arthrography (70%-90% and 60%-75%, respectively). Nuclear arthrography had higher diagnostic accuracy than 99mTc-MDP images alone. CONCLUSION: Nuclear arthrography is a sensitive technique for detection of loosening of prostheses, offering added value over radiographic arthrography and bone scanning alone, especially for evaluation of the femoral component. Radiographic arthrography remains necessary not only for adequate deposition of contrast agents but also for detailed evaluation of osseous structures.

Fluorine-18-fluorodeoxyglucose assessment of glucose metabolism in bone tumors.

UNLABELLED: In our study, we investigate the glucose metabolism of various types of bone lesions with 18F-fluorodeoxyglucose (FDG) PET. METHODS: Twenty-six patients showing clinical and radiographic symptoms of a malignant bone tumor were included. Histological examination after the PET study revealed 19 malignant and 7 benign tumors. PET images were corrected for attenuation. Arterial blood samples were taken to establish the input function. The metabolic rate of glucose consumption (MRglc) was calculated for the whole tumor, for the 10 pixels with maximum activity and for contralateral normal muscle tissue. RESULTS: All lesions were clearly visualized with 18F-FDG PET except for a small infarction of the humerus. All the other lesions had increased glucose metabolism compared to surrounding and contralateral muscle tissue. Both maximum and average MRglc for benign, as well as malignant, lesions were significantly higher than for contralateral normal tissue. The maximum and average MRglc were not higher for malignant as opposed to benign lesions. There was a large overlap between the MRglc of benign and malignant lesions. CONCLUSION: Fluorine-18-FDG PET appears suitable to visualize bone tumors. With the quantification of glucose metabolism, it is not possible to differentiate between benign and malignant bone tumors. There does not seem to be a clear correlation between the MRglc and the biologic aggressiveness of the neoplasms.

Scintigraphic detection of bone and joint infections with indium-111-labeled nonspecific polyclonal human immunoglobulin G.

The utility of indium-111-(111In) labeled immunoglobulin G (IgG) to detect infection of bone and adjacent tissues was investigated. Proof of infection was obtained by cultures taken at surgery. All 32 patients showed focally increased uptake on the technetium-99m- (99mTc) methylene diphosphonate (MDP) skeletal scintigraphies. Labeled immunoglobulin correctly identified presence, location, extent and soft-tissue involvement of the suspected inflammatory site. In these patients, focally increasing accumulation was noted over 48 hr. Discrimination between infection and sterile inflammatory lesions was not possible. Two fractures, 6-mo-old, and an aseptic loosening of a total-hip prosthesis were not visualized. Side effects after the immunoglobulin administration were not observed. Radiolabeled immunoglobulin is a new and safe radiopharmaceutical for the investigation of infectious bone and joint disease. The sensitivity of this agent appears at least as high as that of labeled leukocytes. However, labeled immunoglobulin can easily be prepared in every nuclear medicine department.

Backgrounds of antibiotic-loaded bone cement and prosthesis-related infection.

Antibiotic-loaded bone cement has been in use for over 30 years for the fixation of total joint arthroplasties, although its mechanism of action is still poorly understood. This review presents the backgrounds of bone cements, prosthesis-related infection and antibiotic-loaded bone cements. It is shown that antibiotic-loaded bone cement has a significant effect on bacteria, particularly in animal and clinical studies. However, recently, antimicrobial resistance among bacteria has been ascribed to the antibiotic-loaded bone cement. The unresolved issues both regarding the action of antibiotic-loaded bone cement and the nature of the antimicrobial resistance necessitate further research into the interaction of antibiotic-loaded bone cement and bacteria.

Cytotoxic, allergic and genotoxic activity of a nickel-titanium alloy.

The nearly equiatomic nickel-titanium (NiTi) alloy is known for its shape memory properties. These properties can be put to excellent use in various biomedical applications, such as wires for orthodontic tooth alignment and osteosynthesis staples. The aim of this study was to evaluate the short-term biological safety of the NiTi alloy. We carried out an end-point dilution minimal essential medium (MEM) extract cytotoxicity test, a guinea-pig sensitization test and two genotoxicity tests: the Salmonella reverse mutation test and the chromosomal aberration test. The NiTi alloy showed no cytotoxic, allergic or genotoxic activity, similar to the clinical reference control material AISI 316 LVM stainless steel. This promising biological behaviour was most likely due to a minimal release of ions and in that way a reflection of the good corrosion resistance of the NiTi alloy. Given these very good results, together with the good tissue compatibility as shown in several implantation studies in the literature, the NiTi alloy can be regarded as a biologically safe implant material with many promising clinical applications.

Staphylococcus aureus biofilm formation on different gentamicin-loaded polymethylmethacrylate bone cements.

In this in vitro study, the formation of a Staphylococcus aureus biofilm on six gentamicin-loaded bone cements (CMW1, CMW3, CMW Endurance, CMW2000, Palacos, and Palamed) was determined in a modified Robbins device over a 3 days time span and related with previously (Van de Belt et al., Biomaterials 21 (2000) 1981) measured kinetics of antibiotic release by these cement brands. The influence of gentamicin release on biofilm formation was quantified by expressing the number of colony-forming units on gentamicin-loaded cement relative to the number of viable organisms on unloaded cement of the same brand. Biofilms formed on all gentamicin-loaded cements, despite the release of antibiotics, followed a consistent pattern in time with a maximum number of colony-forming units per unit cement area found between 24 and 30 h after inoculation. None of the gentamicin-loaded cements showed a reduction in biofilm formation relative to unloaded cements within 6 h after inoculation, whereas only gentamicin-loaded CMW1 and Palacos reduced biofilm formation 24 h after inoculation. Alternatively, CMW Endurance, CMW2000, and Palamed did not exhibit any initial reductions in biofilm formation, but effects started after 72, 48, and 72 h, respectively. Biofilm reduction by gentamicin-loaded CMW3 lasted the longest from 24 to 72 h. Interestingly, each cement seemed to have a different "window-of-effectiveness" with regard to reduction in biofilm formation that did not relate with the gentamicin-release kinetics. Summarising, this study demonstrates that although gentamicin loading of bone cements yields reductions in biofilm formation, S. aureus is able to grow on gentamicin-loaded bone cements.

Electrochemical and surface characterization of a nickel-titanium alloy.

For clinical implantation purposes of shape memory metals the nearly equiatomic nickel-titanium (NiTi) alloy is generally used. In this study, the corrosion properties and surface characteristics of this alloy were investigated and compared with two reference controls, AISI 316 LVM stainless steel and Ti6A14V. The anodic polarization curves, performed in Hanks' solution at 37 degrees C, demonstrated a passive behaviour for the NiTi alloy. A more pronounced difference between the corrosion and breakdown potential, i.e. a better resistance to chemical breakdown of passivity was found for the NiTi alloy compared to AISI 316 LVM. X-ray electron spectroscopy (XPS) and scanning electron microscopy (SEM) were undertaken to study the elemental composition and structure of the surface films prior to, and after immersion in Hanks' solution. The passive film on the NiTi alloy consists of a mainly TiO2-based oxide with minimal amounts of nickel in the outermost surface layers. After immersion in Hanks' solution the growth of a calcium-phosphate layer was observed. The passive diffusion of nickel from the NiTi alloy, measured by atomic absorption spectrophotometry reduced significantly in time from an initial release rate of 14.5 x 10(-7) microg cm(-2) s(-1) to a nickel release that could not detect anymore after 10 days. It is suggested that the good corrosion properties of the NiTi alloy and the related promising biological response, as reported in literature, may be ascribed to the presence of mainly a TiO2-based surface layer and its specific properties, including the formation of a calcium-phosphate layer after exposure to a bioenvironment.

Surface roughness, porosity and wettability of gentamicin-loaded bone cements and their antibiotic release.

In this study, the release of gentamicin as a function of time was measured for six different gentamicin-loaded bone cements and related with the surface roughness, porosity and wettability of the cements. Initial release rates varied little between the six bone cements (CMW1, CMW3, CMW Endurance, CMW 2000, Palacos, and Palamed) and ranged from 8.6 to 14.1 microg/cm2/h. The total amounts of gentamicin released after 1 week varied between 4.0 and 5.3% of the total amount of antibiotic incorporated for the CMW cements and was 8.4% for Palacos. Palamed released after 1 week significantly more of the gentamicin incorporated (17.0%). The wettability of all cements was similar (water contact angles between 70 and 80 degrees), but the surface roughness and the porosity of the cements varied markedly. Initial release rates increased with surface roughness, although the correlation coefficient was low (0.64), while total amounts released increased linearly (correlation coefficient 0.97) with the bulk porosity of the cements. Consequently, it can be concluded that the release kinetics of gentamicin from bone cements is controlled by a combination of surface roughness and porosity.

Penetration of isoniazid, rifampicin and pyrazinamide in tuberculous pleural effusion and psoas abscess.

SETTING: Tuberculosis Centre, University Medical Centre, Groningen, The Netherlands. OBJECTIVES: To study intralesional concentrations of isoniazid (INH), rifampicin (RMP) and pyrazinamide (PZA) in tuberculous pleural effusions and psoas abscesses, and to compare these to reference serum values and minimal inhibitory concentration (MIC). DESIGN: Intralesional concentrations were measured 2 h after drug administration (six pleural effusions, 10 psoas abscesses). RESULTS: A wide range of concentrations was found for pleural effusions and psoas abscesses. Concentrations were below MIC values in none of 15 patients for INH, in two of 13 for RMP, and in eight of nine for PZA. The Cmax:MIC ratio was always >4 for INH, in four of 13 for RMP, and in none of nine for PZA. In 5/8 patients receiving all three drugs, both RMP and PZA had Cmax:MIC ratios <4, indicating sub-therapeutic drug levels. CONCLUSION: Penetration of INH was always sufficient, penetration of RMP mostly below the desired ratio, and for PZA on average 10 times too low. Five of eight patients on all three drugs had Cmax:MIC ratios <4. This indicates intralesional sub-therapeutic drug levels for RMP and PZA, and local monotherapy with INH. This could induce drug resistance. Drainage as additional therapy seems indicated.

External and internal hemipelvectomy for sarcomas of the pelvic girdle: consequences of limb-salvage treatment.

The outcome of different limb-saving treatment modalities for pelvic girdle sarcoma is controversial. The oncological and functional results after 11 external and 10 internal hemipelvectomies and the consequences of limb-salvage treatment were studied in 21 consecutive patients with primary bone (19 patients) or soft tissue sarcoma (two patients) of the pelvic girdle. Following external hemipelvectomy, 10 patients (91%) died after a median follow-up of 1.6 years (range: 0.3-7.1). Isolated local recurrences occurred in three patients (27%), with concomitant distant failure in one (9%), while isolated distant failure occurred in six patients (55%). The rate of flap necrosis and wound infection following external hemipelvectomy were both 25%. Following internal hemipelvectomy, nine patients (90%) were alive without evidence of disease after a median follow-up of 6.6 years (range: 2.3-16.0). Concomitant local and distant failures were found in one patient (10%). Reconstruction-related complications necessitated revisional procedures in five of seven patients (72%), leading to external hemipelvectomy in one. Patients with a locally advanced pelvic girdle sarcoma who are unable to undergo an internal hemipelvectomy have a worse prognosis than patients who undergo an internal hemipelvectomy. An internal hemipelvectomy is not attended by an increased risk of local failure, but is by long-term local complications, requiring extensive surgical procedures.

Use of the Swanson silicone trapezium implant for treatment of primary osteoarthritis : long-term results.

BACKGROUND: Instability of the prosthesis and silicone-induced synovitis have led most surgeons to abandon use of the Swanson trapezium implant for the treatment of primary osteoarthritis. However, the literature contains little information on the results of long-term follow-up. The present study was conducted to establish the long-term results and to highlight the problems associated with the implant. METHODS: Thirty-five patients (forty-five implants) of our initial forty-five patients (fifty-seven implants) were available for clinical review. The mean duration of follow-up was 13.8 years. The objective result was assessed with a 40-point clinical scoring system. The subjective result was measured with a visual analog scale. A clinical score of 30 to 40 points and a subjective score of 8, 9, or 10 points were considered a good-to-excellent result. Radiographs were evaluated to determine the position and deformation of the prosthesis and to check for osteolytic changes of the bone, indicating silicone-induced synovitis. RESULTS: The overall clinical and subjective results were good for twenty-seven thumbs (60%). Eighteen thumbs (40%) had a dislocation, and nine of them had a revision. Three more revisions were carried out because of silicone-induced synovitis, persistent pain after reflex sympathetic dystrophy, and deep infection in one thumb each. Revision surgery consisted of resection of the implant, with or without tendon interposition, or implantation of a new prosthesis. Of the thirty-two prostheses (thirty that had not been revised and two that had been revised) for which follow-up radiographs were available, six (19%) showed wear and deformation and five (16%) also were associated with osteolytic changes. CONCLUSIONS: The main problem associated with the prosthesis was dislocation. Surgical measures to improve stability did not prevent this complication. The results after revision because of dislocation were no better than those associated with unrevised dislocated implants. In addition to dislocation, radiographic signs of silicone-induced synovitis were frequently noted, although they did not necessarily lead to a poor result. We concluded that the results after long-term follow-up of the Swanson silicone trapezium implant for the treatment of primary osteoarthritis were poor and that our decision to stop using this implant in 1991 was correct.

[Radiologische Besonderheiten einer bilateral vererblichen Mikro-Epiphysendysplasie - deutliche Entität einer Skelettdysplasie]. / Radiological features of bilateral hereditary micro-epiphyseal dysplasia--a distinct entity in the skeletal dysplasias.

AIM: To prove that bilateral hereditary micro-epiphyseal dysplasia (BHMED), first described by Elsbach in 1959, is a distinct disorder radiologically as well as clinically, compared with multiple epiphyseal dysplasia (MED). MATERIAL AND METHODS: We used the data of the revised pedigree with 84 family members, performed a medical history, physical examination and made a radiological evaluation for defining a clinical and radiological phenotype of BHMED family members. We used blood samples for genetic analysis. RESULTS: Although there is a clear clinical picture of the dysplasia, the radiological signs are more reliable for making the diagnosis. Especially the typical deformity of the hip and knee joint are diagnostic for BHMED. By linkage analysis we excluded linkage with the three known MED-loci (EDM1, EDM2 and EDM3). CONCLUSION: BHMED is indeed an entity that is distinct from common multiple epiphyseal dysplasia (MED), clinically, as well as radiologically and genetically.

MR imaging of 22 Charnley-Müller total hip prostheses.

To find out whether MR imaging is contraindicated in patients with metallic implants or can be a routine diagnostic procedure, MR investigations in 18 patients with 22 Charnley-Müller total hip prostheses were performed on a 0.5 T Gyroscan S 5, Philips. No adverse reactions during or post MR investigation were encountered. The imaging of the soft tissue was superior to CT and showed less distortion. The diagnosis of loosening, by detection of demarcation lines at the interfaces was at its best in the distal part of the femoral stem prosthesis and was poor in the acetabular component and in the upper part of the stem prosthesis due to artifacts.

Long-term results of patellofemoral arthroplasty. A report of 56 arthroplasties with 17 years of follow-up.

We studied retrospectively the outcome of patellofemoral arthroplasty (PFA) using the Richards prosthesis in 51 patients (56 knees). Their mean age was 50 years (30 to 77). In 43 patients (45 knees), the American Knee Society score and the patients' subjective judgement were assessed. Excellent or good results were obtained in 86% of cases at a mean follow-up of 17 years (15 to 21). Because of ongoing tibiofemoral osteoarthritis, two patients required a high tibial osteotomy and ten PFAs were converted to a total knee arthroplasty after a mean of 15.6 years (10 to 21). The PFAs were stable during follow-up with a loosening rate of only 2%. We conclude that a patellofemoral prosthesis is a good treatment option with successful long-term results in middle-aged patients with radiologically documented, isolated, patellofemoral osteoarthritis.