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Biomedical subjects

P Patka

Publications and source records attributed to P Patka.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Biodegradable implants in fracture fixation: state of the art].

Operative fracture repair in trauma surgery is currently performed using metal implants. These metal implants often are removed during a second, retrieval operation. Biodegradable fracture fixation devices have been used clinically since the late seventies. Most bioresorbable implants are manufactured from polymers. The polylactides, polyglycolides and co-polymers slowly degrade into small components that are excreted from the human body via natural pathways and removal operations after fracture surgery are not necessary. Due to the limited mechanical properties, the polymer screws and pins are mostly used in the treatment of non weight-baring simple fractures of the ankle, elbow, hand and foot. In view of the progressing technical developments, new materials will be developed and tested for clinical use in the coming decades.

Absorbable Implants↗
PubMed2000

Evaluation of strength of healing fractures with dual energy Xray absorptiometry.

Dual energy xray absorptiometry was investigated as a method for evaluation of the strength of closed tibial fractures. In 40 goats, a closed midshaft fracture was created in the left tibia. The fractures were stabilized with an external fixator. After 2 weeks (n = 21) and after 4 weeks (n = 19), both tibias were explanted and, using dual energy xray absorptiometry, bone mineral density and bone mineral content were measured in a 1 cm region. With nondestructive bending tests, area ratio and stiffness index were determined and torsional strength and torsional stiffness were determined with a torsional test to failure. Linear regression analysis was used to calculate the squared correlation coefficients for the relations between dual energy xray absorptiometry and the outcome of the mechanical tests. The squared correlation coefficients for the relation between bone mineral density and torsional strength, torsional stiffness, and area ratio and stiffness index were 0.72, 0.76, 0.64, and 0.72, respectively. The squared correlation coefficients for the relation between bone mineral content and these mechanical parameters were 0.72, 0.77, 0.63, and 0.77, respectively. The results using dual energy xray absorptiometry indicate the strength of healing closed fractures. Additional research is required to investigate specific aspects of this technique.

Absorptiometry, Photon↗
PubMed2000

The effect of alendronate on bone mass after distal forearm fracture.

Fracture and immobilization of an extremity lead to bone loss at the fracture and at adjacent sites. We conducted a 1-year, single-center, prospective, randomized, double-blind study to determine whether bone loss would occur in the distal radius after a Colles' fracture and whether this loss could be prevented using an antiresorptive drug (alendronate). Thirty-seven women with a recent fracture of the distal forearm and low bone mineral density (BMD) of the lumbar spine were randomized to receive either 10 mg alendronate daily or placebo. BMD of both forearms was measured at baseline and after 3, 6, and 12 months. The results of four women who developed reflex sympathetic dystrophy were not included in the analysis. In the placebo group, there was a significant reduction at 3 months and 6 months in BMD of total radius (p < 0.01), one-third distal radius (p < 0.01), middistal radius (p < 0.05), and ultradistal radius (p < 0.01) on the fractured side. The loss in BMD at one-third distal radius remained significant at month 12 (p < or = 0.001). In the alendronate group BMD of total distal radius, one-third distal radius, and middistal radius at the fractured side remained unchanged. BMD of ultradistal radius increased significantly at months 3, 6, and 12, compared with baseline (p < 0.05). The difference between the two treatment groups was significant at 3 months and 6 months and borderline significant (p = 0.054) after 1 year in total distal radius. In ultradistal radius the differences were significant at all time points. We conclude that BMD of the distal radius of a recently fractured forearm decreases significantly in the 6 months after fracture and the resulting deficit remains evident at least 1 year after fracture. This bone loss can be prevented by alendronate.

Absorptiometry, Photon↗
PubMed2000

Destination of debris during intramedullary reaming. An experimental study on sheep femurs.

This study was designed to further explain the better fracture healing in fractures treated with a reamed nail. It investigates the location and quantity of the reaming debris in an ex vivo animal model to test the autograft theory. In 10 cadaveric sheep femurs, a 5-mm semicircular gap was created at the midshaft. The medullary cavity was opened and the reaming debris that dropped from the gap during reaming and the debris from the proximal opening were collected and weighed separately. The mean harvest of reaming debris at the gap was 0.99 g +/- 0.12 g (24%) and from the proximal opening at the medullary cavity 3.08 g +/- 0.31 g (76%) (total 4.07 +/- 0.34 g). This study proves that a significant amount of reaming debris collects at an artificial fracture gap during reaming of the medullary cavity. This finding supports the theory of bone autografting.

Animals↗
PubMed1999

New segmental long bone defect model in sheep: quantitative analysis of healing with dual energy x-ray absorptiometry.

An appropriate animal model is required for the study of treatments that enhance bone healing. A new segmental long bone defect model was developed for this purpose, and dual energy x-ray absorptiometry was used to quantify healing of this bone defect. In 15 sheep, a 3-cm segmental defect was created in the left tibia and fixed with an interlocking intramedullary nail. In seven animals, the defect was left empty for the assessment of the spontaneous healing response. In eight animals serving as a positive control, autologous bone grafting was performed. After 12 weeks, healing was evaluated with radiographs, a torsional test to failure, and dual energy x-ray absorptiometry. The mechanical test results were used for the assessment of unions and nonunions. Radiographic determination of nonunion was not reliably accomplished in this model. By means of dual energy x-ray absorptiometry, bone mineral density and content were measured in the middle of the defect. Bone mineral density was 91+/-7% (mean +/- SEM) and 72+/-6% that of the contralateral intact tibia in, respectively, the autologous bone-grafting and empty defect groups (p = 0.04). For bone mineral content, the values were, respectively, 117+/-18 and 82+/-9% (p = 0.07). Torsional strength and stiffness were also higher, although not significantly, in the group with autologous bone grafting than in that with the empty defect. Bone mineral density and content were closely related to the torsional properties (r2 ranged from 0.76 to 0.85, p < or = 0.0001). Because interlocking intramedullary nailing is a very common fixation method in patients, the newly developed segmental defect model has clinical relevance. The interlocking intramedullary nail provided adequate stability without implant failure. This model may be useful for the study of treatments that affect bone healing, and dual energy x-ray absorptiometry may be somewhat helpful in the analysis of healing of this bone defect.

Absorptiometry, Photon↗
PubMed1999

Bone tissue response to biodegradable polymers used for intra medullary fracture fixation: a long-term in vivo study in sheep femora.

Since the degradability of the synthetic polymers used for fracture fixation is still unclear, a research project with biodegradable interlocking nails with a longterm implantation period has been started. In 21 female sheep a complete mid-shaft osteotomy of the left femur was performed to mimic a fracture of the femoral shaft. For the fixation, an intramedullary stainless-steel interlocking nail, a PLA rod or a PLA/PGA rod was used. After 30 months of implantation the histological results of these three materials were examined. In contrast to most reports the degradation rate of both polymers was much lower than the suggested ultimate period of two years. Even the tissue response was more pronounced than expected and this reaction can imply certain risks for repulsion. One can conclude that the volume quantity of polymeric implant in the bony tissue must be reduced if possible to avoid severe foreign body responses. The immunologic responses and the clinical consequences need more studies. The degradation behavior of the polymer is still not under control.

Animals↗
PubMed1999

Long-term consequences of fracture of the lower leg: cross-sectional study and long-term longitudinal follow-up of bone mineral density in the hip after fracture of lower leg.

The purpose of this study was to investigate whether bone loss in the hip, occurring after a fracture of the lower leg, persists many years after the fracture. In a long-term follow-up we measured bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) of both hips and the lumbar spine in a group of 11 patients, 5 years after a fracture of the lower leg. These patients were part of an earlier study, evaluating bone loss in the hip, up to 1 year after fracture of the lower leg. In this follow-up study, 5 years after fracture, loss from baseline BMD in the trochanteric region of the ipsilateral hip was 4.7% (p=0.04), whereas after a year in this group there was a decrease of 12.5% from baseline. On the contralateral side, hardly any change occurred. In the ipsilateral femoral neck, 5 years after fracture, BMD decreased by 2.9% (p=0.10), after 1 year loss from baseline was 5.1%. In a cross-sectional study we examined the differences in BMD of both hips, measured by DXA, in a group of 19 elderly patients reporting a fracture of the lower leg, with a mean time of 9.3 years after fracture. In this study, we found a 4.7% lower BMD in the trochanteric region of the hip on the fractured side compared with the nonfractured side (p=0.006), and a 2.9% lower BMD in the femoral neck (p=0.25). We conclude that, after fracture of the lower leg, BMD in the ipsilateral hip decreases significantly, with maximal bone loss after 1 year. After 5 years recovery has occurred, but not to baseline. Thereafter, significant excess bone loss is still observed in the trochanteric region. This persisting lower BMD may lead to an increased risk of another fracture in later years.

Aged↗
PubMed1999

Myocardial contusion as a result of isolated sternal fractures: a fact or a myth?

Isolated sternal fractures are seen with an increasing frequency in traffic road accidents especially after the introduction of the seatbelt legislation. In most cases, the victims are young, otherwise healthy individuals. The medical records of all patients who were treated with a diagnosis of sternal fracture over the past 10 years were retrospectively reviewed. All patients with a radiologic diagnosis of sternal fracture were admitted for cardiac monitoring for at least 24 hours. ECG, determinations of cardiac enzyme levels CK (creatinephosphokinase) and CK-MB and evaluation by a cardiologist were routinely performed. An echocardiography was performed when indicated by the cardiologist. A total of 86 patients had sustained a sternal fracture during the 10-year study period. There were 39 males and 47 females with a mean age of 50 years (range 15-97 years). Serial 12-lead electrocardiograms, which were performed in 83 (97%) patients, revealed no information about myocardial contusion or cardiac arrhythmias with consequent therapy. In eight patients, a significant elevation in cardiac enzyme levels (elevation of CK-MB fraction above 10% of CK) was observed. All were normalized within 24 hours without development of any arrhythmias. Echocardiography was performed in 31 patients. In two patients, dyskinesia of the right ventricle (without enzyme elevations or arrhythmias) was observed. Within 24 hours these abnormalities resolved. The cardiac rhythm was monitored in 61 (71%) patients for a total of 1550 hours. No arrhythmias were observed. The cardiac enzyme studies, ECG and echocardiography revealed no consequent information about arrhythmias. In case of a sternal fracture, we recommend a chest X-ray to exclude other associated intrathoracic injuries. If no abnormalities are identified, admission to hospital is not necessary.

Accidents, Traffic↗
PubMed1999

The influence of hydroxyapatite granules on the healing of a segmental defect filled with autologous bone marrow.

Hydroxyapatite(HA) ceramics are frequently used as a bone graft substitutes for the filling of bony defects. The addition of autologous bone marrow to HA ceramics does improve defect healing. There is conflicting evidence in the literature whether autologous bone marrow transplantation alone is as effective as the combination of HA ceramics and bone marrow combined. It was the purpose of this study to identify the role of additional HA ceramic granules on the healing of a sheep tibia segmental defect filled with autologous bone marrow. After permission of the local animal rights committee was obtained, a 3 cm segmental defect in the midshaft of 31 adult sheep was stabilized with an unreamed tibia nail. The animals were divided into 4 groups according to the mode of defect filling: HA plus autologous bone marrow (HA + MAR) (n = 8), autologous bone marrow (MAR) (n = 9), empty defect (DEF) (n = 6), cancellous bone graft (CAN) (n = 8). After three months follow up animals were sacrificed and analysed for the key parameters of union and maximum torque at failure. One nonunion was present in each of the HA + MAR, MAR, and CAN groups. Four of the six animals in the DEF group developed a nonunion. Maximum torque at failure was reported as percentage of the intact contralateral tibia: HA + MAR 39% +/- 24%, MAR 26% +/- 17%, DEF 22% +/- 13%, CAN 41% +/- 20%. The difference between the groups was statistically significant, but appeared to be relevant. We conclude from our data, that HA ceramics do improve healing of a segmental defect in the sheep tibia filled with autologous bone marrow. The results of this combination are comparable to cancellous autograft.

Animals↗
PubMed1998

[Bone transplantation and bone replacement materials].

There is a growing need for immediately available material with appropriate qualities for reconstruction of large bone defects. Autologous spongy bone grafts are optimal as to biocompatibility, but are in short supply. Allogenic and xenogenic bone grafts evoke an immunological reaction after implantation and are not biocompatible. In the last thirty years ceramic implants and composites have been developed for bone substitution. New calcium phosphate bone substitutes undergo processes of resorption and precipitation of carbonate apatite that play a part in formation of new bone. These materials are easy to use because of their pastelike consistence. Resorption properties are influenced by particle size, crystallinity and composition. So far, no serious adverse reactions were reported. More clinical experience is necessary especially with composites and combinations with antibiotics, bone growth factors and collagen, to specify the place of these modern calcium phosphates in bone replacement and bone substitution.

Apatites↗
PubMed1998

[Resorbable rods and screws for fixation of ankle fractures. A randomized clinical prospective study].

A prospective randomized clinical trial was performed to evaluate the use of self-reinforced absorbable composites (Biofix) in the fixation of ankle fractures. The aim of this study was to demonstrate that fixation with Biofix rods and screws is as good as the standard A.O. fixation. The benefits of Biofix rods and screws are: a reduction in costs since no secondary operation is needed, prevention of stress-shielding and thereby diminishing the risk of bone porosity. Patients aged between 16 and 75 years old with closed, non-comminuted fractures of the lateral and/or medial malleolus and dislocation of the fracture fragments greater than 2 mm were included in the study. 22 patients were treated with Biofix rods and screws and the control group of 19 patients with a standard technique. After 3, 6 and 12 months, rontgenograms were taken. At the same time functional results were evaluated following the criteria of Olerud and Molander. Two patients were withdrawn from the trial for non-medical reasons. 22 patients (12 from the Biofix group, 10 from the AO group) operated two or more years ago were contacted to see if any complications had occurred since they were last seen. In 4 cases a Biofix screw broke down just beneath the head during insertion. This did not result in an insufficient fixation of the fracture. There were no early post-operative complications. The functional and rontgenological results in both groups were equal. In three cases a sterile sinus developed at the site of screw insertion. Biofix rods and screws, made of polylactic acid, are a good alternative for the fixation of fractures of the ankle. The use of resorbable fracture fixation material has the advantage that a second operation to remove osteosynthesis material is not necessary. The long term results are good. There is, however, a possibility of development of tissue reaction to the resorbable material.

Adolescent↗
PubMed1998

Quantification of fracture healing with three-dimensional computed tomography.

Quantitative methods are necessary for an objective evaluation of fracture healing. Three-dimensional computed tomography (CT) for the measurement of callus volume and density could be such a method and was investigated in an animal model. In 23 goats a closed tibial fracture was created and stabilized with a cast. The animals were killed at 2, 4 and 6 weeks for radiographical, CT and biomechanical analysis. From the CT scans a three-dimensional reconstruction of the callus was made to measure its volume and mean density. At 2 weeks the callus volume had already reached its maximum. In contrast, callus density, torsional strength and torsional stiffness increased over time (P < 0.0001, analysis of variance, ANOVA). Multiple regression analysis showed that the callus volume was not related to the torsional properties. However, callus density was a significant explanatory variable for both torsional strength (R2 = 0.72, P < 0.0001) and torsional stiffness (R2 = 0.82, P < 0.0001). Therefore, callus density as measured by three-dimensional CT is a predictor of the extent of fracture consolidation. CT with three-dimensional reconstruction of the callus seems a valid technique for the quantification of fracture healing.

Analysis of Variance↗
PubMed1998

Representative assessment of long bone shaft biomechanical properties: an optimized testing method.

Whole bone bending tests are commonly used in mechanical evaluation of long bones. Reliable information about the midshaft can only be obtained if the bending moment is uniformly distributed along the shaft, and if the distribution of the bending stress is not adversely influenced by rigid clamping of the bone ends. A testing device was developed to determine bending stiffness of long bones in 24 directions, perpendicular to the bone axis. For optimal distribution of bending moment and stress, four-point bending was performed, and bone ends were simply supported, not rigidly clamped. The method was validated by repeated testing of a stainless steel rod, and a sheep femur. Left-right ratios were assessed twice in 2 groups of 5 sheep: one control group, and one group in which the left femur was stabilized with a stainless steel interlocking nail for 2.5 yr, after a midshaft osteotomy. Test results obtained with the steel rod reproducibly were close to predicted values. Measurements with the sheep femurs were reproducible and precise for 3 of the 4 parameters of the bending test. Stiffness parameters were significantly higher in the operated sheep than in the control group. We conclude that the method described here provides accurate and reproducible information, which is representative for the long bone shaft.

Animals↗
PubMed1998

Biodegradable interlocking nails for fracture fixation.

Serious problems such as stress shielding, allergic reactions, and corrosion are associated with the use of metallic fracture fixation devices in fractured long bones. Metal implants often are removed during a second retrieval operation after fracture healing has completed. A biocompatible implant that degrades slowly during implantation would obviate the need for a second operation and save the patient from considerable physical, psychologic, and financial discomfort. The biodegradable implant must provide the fractured limb sufficient support for a certain time, allowing early loading. A gradual transfer of load from the biodegradable implant to the bone would result in a better product of bone healing and avoid stress shielding. In an animal model using adult sheep, two types of biodegradable polymer interlocking nails were tested in comparison with a stainless steel interlocking nail. Fracture healing, mechanical properties of the bones, degradation behavior in vivo and in vitro, and tissue response were monitored during a 2 1/2-year followup study. To detect shifts in acid base relations caused by the release of acid compounds, pH measurements were performed. Fracture healing was unimpaired, and the mechanical test results of all three groups were excellent. Histologic analysis showed a mild inflammatory response, but no pH shifts were observed. The results of this study justify additional research on these promising materials.

Absorbable Implants↗
PubMed1996

Randomised controlled trial of single-dose antibiotic prophylaxis in surgical treatment of closed fractures: the Dutch Trauma Trial.

BACKGROUND: The efficacy of prophylactic antibiotics in fracture surgery remains controversial for lack of well-documented prospective studies. We report here the findings of the Dutch Trauma Trial, a prospective, randomised, double-blind, placebo-controlled study of antibiotic prophylaxis in the primary operative treatment of limb fractures. Ceftriaxone was chosen because of its pharmacokinetic profile, including high serum levels, high tissue penetration, and long elimination half-life, makes it suitable for single-dose prophylaxis. METHODS: Patients aged 18 years or more, attending one of fourteen Dutch centres for acute treatment of closed fractures, were randomly allocated to a single preoperative dose of ceftriaxone 2 g or placebo, and evaluated for development of wound infection and nosocomial infection at 10 days, 30 days, and 120 days. To assess the effects of drop-outs and withdrawals, best-case and worst-case analyses were performed. FINDINGS: A total of 2195 patients were included. The incidence of superficial and deep wound infections after placebo was 8.3%, compared with 3.6% in the ceftriaxone group (p < 0.001, Pearson chi 2-test). The rate of nosocomial infection in the first month was 10.2% with placebo and 2.3% with ceftriaxone (p < 0.001, Pearson chi 2-test). Gram-positive bacteria were found in 74.5% of wound infections and 13.4% of nosocomial infections. INTERPRETATION: Adequate single-dose prophylaxis with a long-acting broad-spectrum antibiotic substantially reduces the incidence of wound infection and early nosocomial infection after surgery for closed fractures.

Adult↗