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Biomedical subjects

P Verheyden

Publications and source records attributed to P Verheyden.

At least 19 recordsLinked to original sources
PubMed2003

[Thoracolumbar spine fractures after conservative and surgical treatment. Dependence of correction loss on fracture level].

QUESTION: This retrospective study presents results after conservative and operative treatment of thoracolumbar fractures as function of its localization. METHODOLOGY: In 2 years 70 patients with A1/A2 fracture were conservatively treated, 38 patients with A3/B/C injury were treated by internal fixtor. For evaluation 3 vertebral sections(Th5-10,Th11-L2,L3-5)were defined. Follow-up took place 1 year after implant removal or end of conservative treatment. RESULTS: The correction-loss was highest in thoracic, lowest in lumbar region. After conservative therapy,correction-loss was located to 3/4 in vertebra itself, after operative treatment especially in adjacent disc spaces. There was no general correlation to complaints. CONCLUSION: In consequence of these results A1/A2-fractures in the upper thoracic spine ( 15 degrees will be stabilized anteriorly, in other regions functional treated. A3-fractures of thoracic spine and thoracolumbar junction will be operated from anterior, in lower lumbar spine (>L3) from dorsal. B- and C-injuries should be instrumented with a combined dorsoventral procedure.

Adolescent↗
PubMed2003

[Tibial plateau fracture--biodegradable bonecement-augmentation].

Between October 1996 and January 1999,29 patients (f:16,m:13,age: 22-86) with fractures of the lateral tibial plateau were operated on arthroscopic,fluoroscopic control or were treated with open reduction and internal fixation. 15 of them were retrospective and 14 prospective analysed. The metaphyseal defect after elevation of the depressed fragment was augmented in 11 cases with autologous spongeous bone grafting,in 9 cases with biodegradable bone cement (Norian SRS). Augmentation was unnecessary in 9 cases. The results according to the Lysholm score and the radiological results were good or excellent. Concerning the kind of augmentation no difference was noted. In the Norian SRS-group the duration of postoperative treatment was shorter than in the other group. The duration of partial weight bearing was shorter too. The results of the present study suggest that an injectable calcium phosphate cement may be a competent material for augmentation in lateral tibial plateau fractures because of the application form and the initial high mechanical stability.

Adult↗
PubMed2001

[Crossed screw osteosynthesis of proximal humerus fractures].

Between March 1997 and October 1999 thirty-one patients with displaced proximal humeral fractures were treated with crossed screw osteosynthesis. Insertion of the screws was realized by using a deltoideo-pectoral approach placing the screws anteriorly and posteriorly in a crossed manner from the distal fragment into the humeral head. Additionally, in all two-part-fractures a tension band was applied. In all three-part-fractures, the greater tuberosity was reattached by additional screws. In 21 patients (14 female, 7 male, median age 62 years, 18-86) a clinical and radiological follow-up (median 18 months, 10-29) was obtained. Fractures were classified as two-part-fractures in 10 patients and as three-part-fractures in 11 patients. According to the Constant-Score, "excellent" and "good" results were achieved in 15 patients, "moderate" results were found in 3 patients. However, in 3 patients results were only "poor" (1 two-part-, 2 three-part-fractures). The complication rate was 29% (premature hardware removal due to head perforation in 3 cases; humeral head necrosis necessitating prosthetic replacement in 2 patients; secondary displacement in 1 case). Crossed screw osteosynthesis represents an justified alternative in the surgical treatment of displaced proximal humeral fractures permitting early functional therapy.

Adolescent↗
PubMed2001

Fracture-dislocations of the elbow joint--strategy for treatment and results.

Between January 1993 and December 1996, 41 patients with fracture dislocation of the elbow joint were treated in our department. In 28 patients (median age 46 years, range 15-77 years; 16 male, 12 female), a clinical and radiological follow-up was obtained after median 34 months (range 12-59 months). In addition to the humero-ulnar dislocation, isolated fractures were present in 13 patients and combined fractures in 15 (all with involvement of the radial head). Primary neurological deficits were found in 7 and open fractures in 3 patients. In 7 patients, primary definitive surgical therapy was carried out by open reduction and internal fixation. A two-step surgical management (initial closed reduction and immobilization, 5 patients with external fixator, 7 with plaster; secondary open surgical procedure) was performed in 12 and conservative treatment in 9 patients. According to the Leipzig Elbow Score, taking subjective, clinical and radiological criteria into consideration, 4 patients achieved 'excellent' and 5 patients a 'good' result. Ten patients were scored 'moderate' and 9 'poor'. The rate of secondary complications necessitating revision was 36%. Poor results were primarily caused by extensive initial soft-tissue damage, delayed definitive surgical therapy, and ectopic heterotopic ossification. In contrast, fracture localization and degree of arthrosis were not of significant importance for the final outcome. In fracture dislocations, the goal is a primary definitive surgical treatment aiming for early postoperative physiotherapy.

Adolescent↗
PubMed2001

Arthroscopic-assisted simultaneous reconstruction of the posterior cruciate ligament and the lateral collateral ligament using hamstrings and absorbable screws.

Arthroscopic-assisted simultaneous reconstruction of the posterior cruciate ligament (PCL) and the lateral collateral ligament (LCL) using hamstring tendon grafts is described. The femoral tunnel is drilled through an incision over the medial femoral condyle and the tibial tunnel through the same skin incision used for harvesting the tendon graft. PCL reconstruction is performed using a 4-strand hamstring tendon graft and absorbable screw fixation. The tendon of the semitendinosus muscle of the uninvolved knee is used as a lateral loop for LCL reconstruction. After pulling the transplant through the fibular head, femoral fixation of the loop is made with an absorbable screw.

Absorbable Implants↗
PubMed2001

[Conservative treatment of dislocated proximal humeral fractures].

Between 11/1989 and 6/1998 52 patients (10 m., 42 f., age median 72 years, 31-88) with proximal humeral fractures have been treated by conservative means (angulation of humeral head > 45 degrees and/or shaft displacement > 1 cm and displacement of greater tuberosity > 0.5 cm). In 37 patients (71%, 31 f., 6 m., age median 75 years, 36-88) a clinical and radiological follow-up could be obtained after median 20 months (3-93). According to the Neer-classification, subcapital 2-part fractures were found in 19 cases and 3-part fractures in 12 cases. 4-part fractures were diagnosed in 6 cases. By using the Constant-Score, the final result was scored "excellent" in 10 patients and "good" in 13 patients. In 7 patients each the results achieved were "moderate" or "poor". The underlying cause for the poor results was primarily due to persisting painful impairment in range of motion and loss of strength. Radiologically, persisting axial deviation was present in 23 cases, arthrosis in 14 patients and humeral head necrosis in 8 patients. Most commonly, poor functional and radiological results occurred in 4-part fractures. However, conservative therapy of displaced 2-part and 3-part fractures is a considerable therapeutical option since the final results are predominantly good. In contrast, due to the poor results after conservative therapy 4-part fractures should be treated surgically.

Adult↗
PubMed2000

[Retropatellar autologous cartilage-bone transplantation. A treatment option in severe cartilage damage].

In a 32 years old professional handball layer, the micro-traumata typical of this game led to retropatellar cartilage lesion, which became sympthomatic following an distortion-impact trauma. Since the patient remains symptomatic after initial conservative treatment as well as arthroscopic chondroplastic, osteo-chondral transplantation was performed. There was a good functional result 6 months after surgery.

Adult↗
PubMed1999

[Pertrochanteric pseudarthrosis. Implant failure - technical error - destiny?].

Pain is not always the leading symptom of a failed union. High primary stability often allows full weight bearing in spite of fracture instability. The difficult diagnosis of a pseudarthrosis is a reason for late intervention. Implant failure and implant breakage are typical signs of surgical underestimation. Finally, the diagnosis "pseudarthrosis" is a fluent one and is defined as a failed fracture healing despite implant stability. Recognition of biological and biomechanical failure, this demands correct evaluation of the global situation and extensive experience in revision surgery on the part of the surgeon.

Biomechanical Phenomena↗
PubMed1999

Open MR imaging in spine surgery: experimental investigations and first clinical experiences.

INTRODUCTION: The latest open MRI technology allows to perform open and closed surgical procedures under real-time imaging. Before performing spinal trauma surgery preclinical examinations had to be done to evaluate the artifacts caused by the implants. METHODS: The MRT presented is a prototype developed by GE. Two vertically positioned magnetic coils are installed in an operation theater. By that means two surgeons are able to access the patient between the two coils. Numerous tests regarding the material of instruments and implants were necessary in advance. The specific size of the artifact depending on the pulse sequence and the positioning within the magnetic field had to be examined. RESULTS: The magnifying factors of the artifact in the spin echo sequence regarding titanium are between 1.7 and 3.2, depending on the direction of the magnetic vector. Regarding stainless steel they are between 8.4 and 8.5. In the gradient echo sequence the factors are between 7.5 and 7.7 for titanium and between 16.9 and 18.0 for stainless steel. The tip of an implant is imaged with an accuracy of 0 to 2 mm. Since September 1997 16 patients with unstable fractures of the thoracic and lumbar spine have been treated by dorsal instrumentation in the open MRI. Percutaneous insertion of the internal fixator has proven a successful minimally invasive procedure. The positioning of the screws in the pedicle is secure, the degree of indirect reduction of the posterior wall of the vertebral body can be imaged immediately. The diameter of the spinal canal can be determined in any plane. DISCUSSION AND CONCLUSION: The open MRI has proven useful in orthopedic and trauma surgery. The size and configuration of the artifacts caused by instruments and implants is predictable. Therefore exact positioning of the implants is achieved more easily. Dorsal instrumentation of unstable thoracolumbar fractures with a percutaneous technique has turned out safe and less traumatic under MR-imaging. Real-time imaging of soft tissue and bone in any plane improves security for the patient and allows the surgeon to work less invasively and more precisely.

Artifacts↗
PubMed1998

Side chain methyl substitution in the delta-opioid receptor antagonist TIPP has an important effect on the activity profile.

The delta-opioid antagonist H-Tyr-Tic-Phe-Phe-OH (TIPP-OH) or its C-terminal amide analogue was systematically modified topologically by substitution of each amino acid residue by all stereoisomers of the corresponding beta-methyl amino acid. The potency and selectivity (delta- vs mu- and kappa-opioid receptor) were evaluated by radioreceptor binding assays. Agonist or antagonist potency were assayed in the mouse vas deferens and in the guinea pig ileum. In the TIPP analogues containing L-beta-methyl amino acids the influence on delta-receptor affinity and on delta-antagonist potency is limited, the [(2S,3R)-beta-MePhe3]TIPP-OH analogue being among the most potent delta-antagonists reported. In the D-beta-methyl amino acid series, the [D-beta-MeTic2] analogues are delta-selective antagonists whereas [D-Tic2]TIPP-NH2 is a delta-agonist. NMR studies did not indicate any influence of the beta-methyl substituent on the conformation of the Tic residue. The [(2R,3S)-beta-MePhe3]TIPP-NH2 is a potent delta-agonist, its C-terminal carboxylic acid analogue being more delta-selective but displaying partial agonism in both the delta- and mu-bioassay. These results constitute further examples of a profound influence of beta-methyl substitution on the potency, selectivity, and signal transduction properties of a peptide.

Animals↗
PubMed1998

[Supramalleolar corrective osteotomy].

The general aspects for the analysis of malalignment of the low tibial region in the three-dimensional space are discussed. Recommendations of clinical and radiological diagnostics prior to low tibial osteotomies are given. Closing wedge, opening wedge, dome-shaped, distraction, rotational and step-shaped osteotomies as well as combined procedures are described. The possibilities of these techniques are pointed out for malalignment after lower leg, pilon and ankle fractures, as well as after trauma of the distal epiphysis of the tibia. Arthroscopy of the ankle is an additional tool for detailed planning of the adequate surgical procedure. The importance of determining an early correction cannot be underestimated.

Ankle Injuries↗
PubMed1998

[Conservative treatment after first traumatic shoulder dislocation].

Between January 1989 and March 1997, 175 patients with traumatic shoulder dislocation were treated by conservative means (median age 41 years, 39 F, 136 M). In 78 patients (17 F, 61 M) a clinical and radiological follow up (median 50 months, range 6-106) could be obtained. Additionally, a diagnostic ultrasound was carried out in all patients. The recurrence rate in the group younger than 30 years (G < 30; n = 35) was 86%; in the group older than 30 years (G > 30; n = 43) it was 21% (P < 0.05). Persisting neurological deficits were found in 6 patients (8%). According to the Rowe score, 16 patients (46%) of the G < 30 achieved excellent or good results, in the G > 30, 29 patients (67%). In 17% of cases, a glenohumeral arthrosis was diagnosed be radiological means. 18% had radiological signs of a previous fracture of the greater tuberosity. Hill-Sachs lesions were identified in 19% of cases. Rotator cuff tears were diagnosed in 9% by ultrasound. No relationship between the duration of immobilization and the recurrence rate was found (P = 0.95). The recurrence rate following primary shoulder dislocation depends primarily on the patients' age.

Adolescent↗
PubMed1997

Conformationally constrained deltorphin analogs with 2-aminotetralin-2-carboxylic acid in position 3.

Two approaches to the design of very active and highly selective delta opioid peptides were used to obtain new deltorpin analogs with altered hydrophobic and stereoelectronic properties. Deltorphin I and II analogs were synthesized involving the substitution of Ile instead of Val at positions 5 and 6 in the address domain and 2-aminotetralin-2-carboxylic acid (Atc) instead of Phe in the message domain. The peptides were agonists in the subnanomolar range in the MVD assay and in the micromolar or higher range in the GPI assay, showing a very high selectivity for delta receptors. A very similar trend could be observed in radioreceptor binding assays in which selective tritiated opioid ligands were used. (R)- and (S)-Atc-deltoriphins exhibited similar Ki values in the binding assay, with almost complete loss of the stereospecificity of the binding. Conformational studies provided evidence for the little disturbance of the backbone conformational equilibrium when Phe3 is replaced by (S)- or (R)-Atc. The use of the Atc constraint gives additional evidence that, during its interaction with the delta receptor, the side chain of residue 3 adopts the trans conformation at chi 1.

Analgesics, Opioid↗
PubMed1997

Location of the three disulfide bonds in an antimicrobial peptide from Amaranthus caudatus using mass spectrometry.

The disulfide bridge pairing of Ac-AMP2, a 30-residue peptide isolated from the seeds of Amaranthus caudatus, is determined using a fast method involving enzymatic fragmentation followed by identification of the fragments with FAB mass spectrometry. The results confirm the location of the three disulfide bridges as previously established by NMR spectroscopy and molecular modelling.

Amino Acid Sequence↗
PubMed1997

[T-plate osteosynthesis in dislocated proximal humerus fractures].

From 1988 through 1995 we operated 48 patients with dislocated humeral fractures using the T-Plate (median age 66 years [20 to 90 years], 32 male, 16 female). After a median 22 months (9 to 60 months) 33 patients were followed up clinically and radiologically. Six patients had suffered a 2-part fracture, 17 a 3-part fracture, and 10 a 4-part fracture. Judged by the Constant score 6 patients reached a very good result, 8 had a good result, 4 a satisfactory and 15 a poor result. Radiologically we saw an arthrosis in 31%, an axial deviation in 50%, and a dislocation of the fragments in 72%. The rate of necrosis of the humeral head was 39%. MRI (17 patients) provided additional relevant information about soft tissue and bone quality and is valuable in the early detection of necrosis of the humeral head. Functionally poor results correlated rather to dislocated fragments and persisting axial deviation than to the type of fracture or the necrosis of the humeral head. The T-plate osteosynthesis is one way to treat dislocated fractures of the proximal humerus, if early operation, correct reposition, and biological principles are respected.

Adult↗
PubMed1996

Importance of the hydrophobic energy: structural determination of a hypoglycemic drug of the meglitinide family by nuclear magnetic resonance and molecular modeling.

The molecular structure of (2S)-2-benzyl-3-(cis-hexahydro-2-isoindolinylcarbonyl) propionic acid (KAD-1229), a hypoglycemic drug of the meglitinide family, was studied by nuclear magnetic resonance (NMR) and molecular modeling. The results of the NMR experiments indicated that KAD-1229 existed in solution in the form of two stable conformers of equal population, called KADI and KADII in this paper. Three different molecular modelings were then applied: the classical molecular dynamics using the commercial Biosym and Hyperchem softwares and the Prot+ program, which is not based on a dynamical study but on a systematic conformational analysis of the molecule, which includes a term that allows the estimation of the hydrophobic interaction. The modeling results showed the following points. First, in contrast with classical molecular dynamics, which uses restraints from two-dimensional nuclear Overhauser effect (NOE) data, the Prot+ KAD structure provides conformations that support experimental NMR data without any external intervention. In the structures in agreement with NMR data, an important hydrophobic interaction between the phenyl cycle and the perhydroisoindole ring of KAD is observed. This interaction, which seems to play a role in the biological activity of the drug, is lost when no restraints are considered in classical molecular dynamics. Second, the difference between KADI and KADII arises mainly from slight distance geometric differences at the level of the perhydroisoindole and the phenyl rings.

Benzamides↗
PubMed1996

H NMR study of the solution structure of Ac-AMP2, a sugar binding antimicrobial protein isolated from Amaranthus caudatus.

The conformation in water of antimicrobial protein 2 from Amaranthus caudatus (Ac-AMP2) was determined using 1H NMR, DIANA and restrained molecular modeling. Ac-AMP2 is a 30 amino acid residue, lectin-like protein that specifically binds to chitin, a polymer of beta-1,4-N-acetyl-D-glucosamine. After sequence specific resonance assignments, a total of 198 distance restraints were collected from 2D NOESY buildup spectra at 500 MHz at pH 2, supplemented by a 2D NOESY spectrum at 600 MHz. The location of the three previously unassigned disulfide bridges was determined from preliminary DIANA structures, using a statistical analysis of intercystinyl distances. The solution structure of Ac-AMP2 is presented as a set of 26 DIANA structures, further refined by restrained molecular dynamics using a simulated annealing protocol in the AMBER force field, with a backbone r.m.s.d. for the well defined Glu3-Cys28 segment of 0.69(+/-0.12) angstroms. The main structural element is an antiparallel beta-sheet from Met13 to Lys23 including a betaI-turn over Gln17-Phel8 with a beta bulge at Gly19. In addition, a beta'I turn over Arg6-Gly7, a beta'III turn over Ser11-Gly12 and a helical turn from Gly24 to Cys28 are identified. This structure is very similar to the equivalent regions of the X-ray structure of wheat germ agglutinin and the NMR structure of hevein.

Amino Acid Sequence↗