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Biomedical subjects

N M Meenen

Publications and source records attributed to N M Meenen.

At least 37 records · Page 2Linked to original sources
PubMed1994

[Reaction of the epiphyseal groove to groove-crossing bore-wire osteosynthesis. Results of a histomorphologic small animal study].

In young rabbits of five to six weeks of age we revealed bony bridging as constant reaction of the epiphyseal cartilage on drilling with a 2 mm diameter trephine into the distal femur growth plate. Gross growth disturbances will be the consequence of such partial closures. For this present study we inserted one 2 mm Kirschner-wire across the epiphyseal plate of the distal femur. The drilling was directed distally. During longitudinal growth the epiphysis moves away from the wire, that remains 8 weeks after the operation completely within the metaphyseal cancellous bone. Four, 8, 12 and 16 weeks postoperatively one group of the rabbits were sacrificed. After radiological examination of the explanted femurs fixation and embedding in methylmetacrylate for morphological examination was performed. Our histological results reveal, that the crossing Kirschner-wire does not irritate the growth plate, even the physiological structure of the epiphyseal cartilage in the direct contact to the metal implant is not altered. The defect within the epiphyseal plate left after the relative retraction of the wire caused by growth activity fills with cancellous bone. Its trabecular structure is markedly thinner than the spongy bone within the metaphysis and shows longitudinal orientation. These trabeculae undergo segmental disruption by the growth pressure of the surrounding epiphyseal plate. In consequence there is no bone bridging and growth alterations by the Kirschner-wire crossing of the epiphyseal plate. This proves experimentally the clinical experienced therapeutic value of Kirschner-wires for internal fixation of dislocated joint injuries.

Animals↗
PubMed1994

[Whiplash injury of the cervical spine--on the role of pre-existing degenerative diseases].

Radiological investigations contribute little in differentiating the problems of patients with whiplash injuries. Nevertheless the more prolonged cases of whiplash injuries must not be attributed to preexisting degenerative disease, despite radiologically-proven medicolegal opinion. In this study, 60 patients who were seen for whiplash injuries in the Department for Trauma and Reconstructive Surgery at the University Hospital Hamburg-Eppendorf for clinical and radiological evaluation, an average of 5.7 years post injury, were divided into two groups (n = 30) depending on radiologically-proven preexisting degenerative changes of the cervical spine. On average the patients with degenerative changes were 11.2 years older than those with healthy vertebral columns and also demonstrated an increase in acute symptoms in the lower cervical spine (cervicobrachial syndrome). The chronicity of individual symptoms such as neck-pain, dizziness, nausea and psychological illness was also observed in both groups. Problems such as paresthesias as well as pain in the shoulder-arm-area appeared to increase in subsequent check-ups, irrespective of the earlier degenerative changes. Patients with typical posterior headaches recovered faster when they had radiologically normal spines. Presenting late, there was a significant accumulation of patients with pre-existing degenerative changes complaining merely of tinnitus. The earlier changes in any individual motion segment do not determine the clinical course of whiplash injuries, but merely represent an area of increased vulnerability to trauma. On the other hand, trauma has not been proven to influence the development or aggravation of degenerative changes in normal or diseased spines. We are not able to differentiate the posttraumatic course from the natural history of the degenerative process, either clinically or radiologically. Considering the involvement of sensitive neurological structures the classical objective organic diagnosis of "whiplash injury" may not be adequate in describing the complaints of patients, and should not be used to justify the rejection of the patients subjective symptoms as mere simulation for financial gains. The evaluation of the patients' X-rays using Arlen's technique sheds no further light on the issue.

Accidents, Traffic↗
PubMed1994

Solubility behaviour of synthetic hydroxyapatites in aqueous solution: influence of amorphous constituents on pH value.

Some hydroxyapatites show a considerable increase of pH in aqueous solution. Rinsing experiments were performed on two commercial samples, and the pH value was plotted as a function of time. The plots lead to the conclusion that a soluble amorphous phase is responsible for the increase in pH. This investigation was supported by X-ray diffraction, microscopy and chemical analyses.

Biocompatible Materials↗
PubMed1993

[Behavior of artificially-induced epiphyseal groove defects in rabbits. Part 2. Transplantation of autologous and homologous groove cartilage].

In this experimental study in rabbits we evaluated histologically the effect of reproducible drill holes through the distal femoral growth plate. We could demonstrate epi-metaphyseal bone-bridging as uniform reaction of the physeal cartilage in response to this traumatisation. The defects have been filled with autologous or homologous epiphyseal cartilage from distal ulnar growth plate. Autologous transplants fulfilled the demand avoiding partial bony closure of the growth plate. Homologous growth cartilage used for filling the defects underwent resorption and could not prevent the development of a bony bridge and growth disturbances.

Animals↗
PubMed1993

[Internal callus distraction in epiphyseal groove defect--a physiologic means of spontaneous correction. Results of a comparative histomorphologic study in a small and large animal experiment].

For this experimental study we removed with a trephine in small (rabbit) and larger (pigs) animals cylinders of 2 mm respectively 8 mm diameter from the central growth plate area of proximal tibia. The direction of burring is in the axial line of the femur proximo-distally; the insertion point of the trephine is chosen on the cheek of the medial femoral condyle. As common reaction to that kind of trauma the defects in growth plates of rabbits become filled with a bone bridge that joins the epiphyseal core to the metaphyseal trabeculae, leading to gross growth disturbances. In pigs a similar solid bridging as first reaction develops, interrupted later by a zone of longitudinal collagen fibre bundles within a non-mineralized matrix. The distending pressure of surrounding intact growth cartilage continuously brakes fracture callus formation and its calcification. Such so-called internal callus distraction leads to unaltered longitudinal bone growth.

Animals↗
PubMed1993

[Isolated fracture of Volkmann's triangle--a unique injury].

25 rare isolated fractures of the dorsal tibial margin out of 2500 ankle-lesions have been analysed. The mechanism consists of extensive plantar flexion followed by axial impact of the astragalus against the posterolateral part of the mortise. The tense condition of the syndesmotic apparatus forces it to pull off the dorsal insertion wedge on the distal tibia with an articular component of different size. Small and undislocated fragments are prevalent. Torn anterior tibiofibular ligament and parts of the interosseous membrane are typical concomitants of this lesion. Neither fibular nor medial structures of the ankle joint have been harmed. Orthotopic bony union of the tibial margin and ligament healing is safe within three weeks of non-weight-bearing immobilisation followed by the same period of walking cast. Large dislocated fragments require operation. Most patients have excellent or good results as our follow-up study confirms.

Adolescent↗
PubMed1993

[Effect of synthetic hydroxyapatite ceramics on long-term cultures of isolated chondrocytes].

This study deals with the influence of hydroxyapatite-ceramic on long-term cultures of rabbit articular chondrocytes. By additioni of granules of this material into the culture wells improval of cell proliferation by factor 12 over a period of twelve weeks is found. More important is the maintaining of the status of differentiation of the chondrocytes, documented by immunoidentification of the expressed collagen I production over collagen II as marker for chondrocytes. In controls without addition of hydroxyapatite-ceramic there is a dynamic increase of collagen I production over the culture period and morphological alteration of the cell shape leading to fibroblast-like cells. As this dedifferentiation is the main problem concerning chondrocytes long-term cultures, the addition of HAC into the culture medium is a simple and effective method enhancing the productivity of the culture system. Moreover this experimental design with chondrocytes as cells familiar with mineralized matrix gives an important proof of the excellent cytocompatibility of the hydroxyapatite-ceramic used in this study.

Animals↗
PubMed1993

[Child abuse--a surgical analysis].

Non-accidental injuries are frequently treated by surgeons without the real reason behind the trauma being identified: The differential diagnosis of child abuse would not be considered in this circumstance. This report gives hints as to the different aspects of this complex type of injury. With our case unusual (atypical) injury patterns have been shown and the diagnostic and therapeutic procedures with child abuse explained from a surgical point of view. It is of central importance to check, whether the trauma history according to the accompanying adults for the actual surgical type of injury is plausible. Incongruencies here must lead to search for further signs of trauma or its residues. When treating these children the surgeon is therefore in a key position especially to prevent future abuse, bearing in mind the special relevance of its striking high recidivation frequency.

Child↗
PubMed1992

[Reparative processes of experimental Aitken III lesion. An animal experiment study].

This present study describes the fine structural aspects of experimentally induced defects of the proximal growth plate of the tibia in rabbits as simulation of epi-/methaphyseal fractures. We evaluated two different defect sizes. As important result we find in narrow defects of 0.5 mm no osseous bridging of the epiphyseal plate whereas with 2 mm defects there is partial transphyseal closure. Growth plate cartilage is thus capable of repairing spontaneously smaller defects.

Animals↗
PubMed1992

[Fat pad signs and supinator fat line in cubital trauma].

The fat pad sign and the supinator fat line (SFL) are valuable diagnostic aids in the evaluation of bony cubital injuries. A total of 377 lateral X-rays of the elbow joint-including 121 fractures--were investigated. The supinator fat line exhibited bar-like and bird-like configurations in 55.9% and 41.8% of healthy test subjects, respectively. In the presence of a fracture, a wavy configuration, directed downwards from, or running parallel to, the upper edge of the radius, was seen in 95% of the cases. If in the event of an injury to the elbow a wavy configuration is seen in association with a positive anterior and/or posterior fat pad sign, bony involvement of the joint-forming elements may justifiably be suspected.

Adipose Tissue↗
PubMed1992

[Fracture lines of the foot].

In follow-up examinations of 112 patients who had been diagnosed as having a sprained foot, bony lesions, confirmed by X-ray films, were found in 96 (85.7%) patients. Up to this time the fractures had not been found in 58 of them. The fractures were found to be distributed in a point-specific location, i.e., a precisely defined anatomical area in 43 cases (44.8%) and a linear presentation in 53 (55.2%). This linear grouping of bony injuries is seen to develop along the path of joints, bones and ligamental insertions that anatomically follow one another in a functional manner. The line-like pattern to these presentation permitted us to develop 3 line sets that could be attributed to specific mechanisms of injury. The lateral line (56.6%) specially follows a supination sprain to the foot. The medial line (20.8%) is seen to follow injuries that involved a blow along the longitudinal axis. The transverse line (22.6%) follows trauma involving the Chopart joint. Six diagrams are presented to illustrate the mechanisms of foot trauma, with their vectors of force and the corresponding injuries that may result. Radiological examples of several clinical cases are given to demonstrate these three fracture lines.

Adolescent↗
PubMed1991

[The supinator fat line--its visualization and validity].

Based on 259 lateral x-ray films of the elbows of healthy subjects, the typical forms of the fat plane overlying the supinator muscle were determined. The forms of this plane in 121 patients who had suffered bony lesions in the elbow joint region were juxtaposed to these x-ray images. Measurements of the proximal distance between the fat plane and the extended tangent of the anterior humeral cortex layer revealed that distances of more than 13 mm in children and of more than 18 mm in adults are highly suspicious of a fracture. The good visualisation of the fat plane by means of various imaging methods is appropriately demonstrated.

Adipose Tissue↗
PubMed1990

[Ligament reinforcement with resorbable PDS cord and early functional after-care. Results of follow-up of surgically managed cruciate ligament injuries].

After operating on the injured cruciate ligaments, immediate mobilization and protection of the healing ligament are indispensible. However, no approach has yet been shown to safely provide both. Therefore, in 1984 we introduced a new technique: the repaired or reconstructed cruciate ligaments are augmented with a biodegradable material - a doubled-over PDS cord, 1.5 mm in diameter. It allows for immediate and safe mobilization. Because of its appropriate elasticity it does not cause "stress shielding." Postoperatively, the patients are mobilized on a motorized frame for 2 weeks. Subsequently, we have used a limited mobilization cast (LMC). Forty-nine out of 63 patients (78%) have now been reexamined for this follow-up study, using the score from the Hospital for Special Surgery and stress X-rays in the Lachmann, position (30 degrees flexion). The results compare favorably with a prior follow-up study of patients from our hospital without PDS augmentation and without early mobilization. The knees in the present study are more stable and have a better range of motion, particularly when the LMC was used.

Adolescent↗
PubMed1989

Radiological diagnosis of cervical trauma at the level C7/T1.

After a car accident a 23-year-old man was found to have rotational luxation of the cervical spine at the level C7/T1. The diagnosis was suspected from indirect signs on the ap X-ray and subsequently confirmed by conventional lateral tomography. Neurological symptoms were not present. Magnetic resonance imaging demonstrated dorsal protrusion of the intervertebral disc.

Adult↗
PubMed1989

[The relation of computed tomography-determined mineral content and the fracture behavior of healthy and metastatic vertebral bodies].

The mineral content of 42 normal and 19 vertebrae with metastases obtained at postmortem was determined by a dual energy method and this was related to their ability to fracture. In the normal vertebrae, this relationship was expressed in the form of a logarithmic function. Amongst vertebrae with osteolytic lesions, liability to fracture increased more rapidly than mineral loss. Vertebrae with osteoblastic metastases showed increased mineral concentration with an increased liability to fracture as compared with normal vertebrae.

Adult↗
PubMed1984

[Value of homologous spongiosa in filling up subchondral bone defects].

The biologic value of cryo-preserved homologous spongiosa for filling up subchondral bone defects shall be investigated. The experimentations are made on rabbits. Three groups are built in order to evaluate the results: Group I: No filling up of defects. Group II: Lining with fresh autologous spongiosa. Group III: Lining with cryo-preserved homologous spongiosa. The lining is performed after standardized subchondral setting of defects in the zone of maximal load of the medial femur condyle. As well in non-filled up defects as after lining with homologous spongiosa, macroscopic and microscopic examinations show between the fourth and eighth postoperative week a hernia of the cartilage-bone lamella. The autologous spongiosa, however, guarantees the stability and vitality of the joint cartilage, as is shown by the results found twelve weeks after the operation. The results may be explained by the retarded osteogenetic power and the long period of catabolism of the homologous spongiosa.

Animals↗