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Biomedical subjects

K Messner

Publications and source records attributed to K Messner.

At least 55 records · Page 3Linked to original sources
PubMed1996

The diagnostic validity of magnetic resonance imaging in acute knee injuries with hemarthrosis. A single-blinded evaluation in 69 patients using high-field MRI before arthroscopy.

Sixty-nine patients with traumatic knee hemarthrosis were evaluated an average of 3 days after trauma by high field (1.5T) magnetic resonance imaging (MRI) using sagittal T1, T2-weighted and coronal 3D-gradient echo images. All knees were arthroscopically examined shortly afterwards. The diagnostic validity of MRI for intraarticular pathology was determined using arthroscopy as golden standard. All patients had pathological findings on arthroscopy. The injuries were sports-related in 77% of the cases. MRI was highly sensitive (86%) and specific (92%) for diagnosis of anterior cruciate ligament tears. Diagnosis of medial meniscal tears showed a 74% sensitivity and 66% specificity. MRI detected lateral meniscal tears in 50% with an 84% specificity. As such, MRI missed 10 significant meniscus ruptures requiring surgical treatment. The sensitivity for partial or total medial collateral ligament tears was 56%, the specificity 93%. Rupture of the medial retinaculum in cases with patellar dislocation or significant damage of articular cartilage were only detected by MRI in a few cases (27% and 20% sensitivity, respectively). MRIs low diagnostic validity for intraarticular pathology with hemarthrosis may be attributed to the shifting paramagnetic properties of the blood remains and catabolic processes in meniscal and chondral tissues during the hemoglobin degradation process. Accordingly, MRI, with the technique used, could neither replace arthroscopy in the diagnosis and screening of acute knee injuries, nor select patients with need for immediate arthroscopic meniscal surgery.

Acute Disease↗
PubMed1996

Natural healing of anterior and posterior attachments of the rabbit meniscus.

The natural healing capacity of the anterior or posterior medial meniscal attachment after radial transection and the effect of such procedures on knee joint cartilage were investigated in 28 skeletally mature New Zealand white rabbits. Either the anterior (n = 14) or the posterior attachment (n = 14) was radially transected in the right knee joint. Fifty percent of the rabbits with each procedure were euthanized at 6 weeks and 50% at 12 weeks. The histologic characteristics of the healing tissue were evaluated, including immunohistochemical demonstration of nerve fibers. Histologic changes in the synovium and articular cartilage were graded for severity and extent. The concentration of proteoglycan fragments in joint fluid was analyzed before operation and at euthanasia. After both procedures, the transected attachment healed in a prolongated position resulting in peripheral displacement of the meniscus. The healing tissue at 6 weeks was composed mainly of granular tissue. By 12 weeks, the healing tissue at the anterior attachment had a ligament like structure, but at the posterior attachment, fibrocartilage like tissue had formed. Nerve fibers were found in the healing tissue, but connections to nerves in normal attachment or meniscal tissues were not found. Increased concentrations of proteoglycan fragments, articular cartilage degeneration, and synovitis were found in the operated knees. These data indicate that although the meniscal attachment can heal in a prolongated position, such a meniscus has lost its mechanical functions. Further, a joint protective function of the neoneurons is doubtful because of the lack of continuity with the adjacent meniscus. Rigid fixation of the attachment seems essential for a functional meniscal substitute.

Animals↗
PubMed1996

In vitro femoral stiffness after femoral neck osteotomy and osteosynthesis with defined surgical errors.

In our search for an osteosynthesis device that would tolerate the surgical errors of the inexperienced surgeon, we tested in vitro femoral stiffness in 75 human osteoporotic femora after internal fixation of a cervical neck osteotomy using three commonly used devices: two von Bahr screws (A. Ericsson AB, Sweden), two cannulated screws (Uppsala type, Olmed AB, Sweden), and two hookpins (LiH, PSAB, Sweden). The first device has its main grip in the cancellous bone by threads; the second has grip in cancellous and subchondral bone by threads; and the third, which has no threads, has its grip in cancellous bone by a hook pin. The intact specimen was in all instances stiffer (22-63%) than the osteosynthesized specimen (p < 0.001). An osteosynthesized femur with perfectly reduced bone ends was 14-23% stiffer than when reduction of the bone ends was insufficient, irrespective of device malposition (p < 0.001). Insufficient reduction of the osteotomy leaving a 20 degrees dorsal angulation of the femoral head combined with too far ventrally placed screws resulted in the lowest femoral stiffness. If reduction of osteotomy was sufficient, screws placed too far ventrally or converging screws did not result in decreased stiffness compared with optimal screw placement. Irrespective of the quality of reduction, osteosynthesis with the Uppsala screw resulted in all instances in a higher stiffness than using the other devices (p < 0.01). With the Uppsala screw design, femoral stiffness after optimal osteosynthesis was reduced by 22% compared with the intact femur, and in the most unfavorable position with combined malreduction and malpositioning it was reduced by 42%. Corresponding values for the von Bahr screws were 29% and 46%, respectively, and for the LiH screws 47% and 63%, respectively. Use of a device with threads and grip in the subchondral bone is recommended for fixation of femoral neck fractures in osteoporotic bone. Furthermore, the importance of anatomical reduction for fracture fixation is emphasized.

Aged↗
PubMed1996

The effect of removal of the medical collateral ligament on subchondral bone and cartilage in the growing rat knee joint.

The growing knee joint in immature rats was chosen as a model to study quantitatively bone apposition and thickness of articular cartilage after surgical removal of the medial collateral ligament. In 32 rats, subchondral bone apposition was assessed by measuring double tetracycline labelling, and the thickness of calcified and uncalcified articular cartilage was measured by image analysis. The results indicate that there was a significant increase in subchondral bone growth after removal of the medial collateral ligament, but no change in thickness of the calcified and uncalcified zones of the articular cartilage in the medial knee compartment. Further, despite an obvious increase in valgus laxity on manual examination, there were no signs of articular cartilage degeneration in any animal. The study shows that traumatic injury to ligaments and joint instability during the growing period may influence the development of subchondral bone in the knee joint.

Animals↗
PubMed1996

The long-term prognosis for severe damage to weight-bearing cartilage in the knee: a 14-year clinical and radiographic follow-up in 28 young athletes.

We examined 28 young athletes with isolated severe chondral damage in the weight-bearing area of the knee joint clinically and radiographically 14 years after arthroscopic diagnosis. Except for Pridie drilling in 3 cases and occasional cartilage shaving or removal of free bodies, no special treatment was given initially. 21 patients were able to return to preinjury team sport activity levels. During the follow-up period, only 3 patients needed repeat surgery with removal of free bodies, and another 2 underwent diagnostic arthroscopy because of persistent pain. At the latest follow-up evaluation, 22 patients had excellent or good knee function. At this time, the patients were mainly involved in individual sports on a physical fitness level. 12 cases had radiographic joint space reduction (< 50%) which was limited to the compartment concerned.

Adolescent↗
PubMed1996

Concentrations of proteoglycan fragments in relation to maturation, sex and time of day: physiologic variations in knee joint fluid of rabbits.

We analyzed the concentrations of proteoglycan fragments in knee joint fluid in 142 rabbits to investigate the effect of physiologic variations--i.e., maturation, sex and time of day. The concentrations of proteoglycan fragments differed significantly between young, adolescent and adult animals and showed an inverse correlation to the stage of maturation of the rabbit. Adolescent male rabbits had higher concentrations than age-matched females. Morning and evening samples had similar concentrations. No relation was found between the proteoglycan fragment concentrations in joint fluid and the cartilage mass. The proteoglycan fragment concentrations in knee joint fluid apparently reflect the metabolic status of growing articular cartilage. There are considerable physiologic variations associated with maturation and sex, and these need to be taken into account when using the proteoglycan fragment concentration as a marker for joint diseases.

Age Factors↗
PubMed1996

Quantitative comparison of soft tissue-bone interface at chondral ligament insertions in the rabbit knee joint.

At chondral ligament insertions the calcified fibrocartilage interdigitates deeply with the lamellar bone. The shape of this interface is formed under physiological loading conditions. For the purpose of morphological comparison between different ligament entheses in the rabbit knee, the number and frequency of interdigitations and thickness of calcified fibrocartilage were quantitated at the femoral insertion of the medial collateral ligament, both insertions of the cruciate ligaments, and the tibial insertion of the patellar ligament. Among the insertions, the femoral insertion of the medial collateral ligament showed the lowest frequency and depth of interdigitations at the soft tissue-bone interface, but had the thickest zone of calcified fibrocartilage. An inverse relationship was found at the insertion interface of the cruciate and patellar ligaments. The frequency and depth of interdigations at the bone-soft tissue interface at different chondral entheses seem to be related to the mechanical strength of the respective ligament; meanwhile it may be hypothesised that the thickness of the calcified fibrocartilage might be more related to the amount of motion which takes place at an insertion.

Animals↗
PubMed1996

The morphology of ligament insertions after failure at low strain velocity: an evaluation of ligament entheses in the rabbit knee.

The morphology of failed rabbit knee entheses is described after in vitro load to failure testing at low strain velocity. Avulsion fracture was the dominant failure mode both for the cruciate ligaments and the medial collateral ligament. The patellar ligament became avulsed in most cases from the patellar insertion. The ligamentous anterior attachment of the medial meniscus failed by a midsubstance rupture and the posterior fibrocartilaginous attachment by a rupture near to the meniscal horn. On histological inspection the failure characteristics usually appeared more elaborate, involving to different degrees all portions of the bone-ligament-bone complexes. Avulsion fracture through subchondral bone was often combined with a partial ligament midsubstance rupture. In few cases avulsion from the cement line was combined with a rupture between the uncalcified fibrocartilage and the ligament. The medial collateral ligament failed in one case entirely at the cement line of its femoral insertion. Horizontal rupture through the calcified fibrocartilage and a vertical cleavage crossing the tidemark were also observed. The superficial portion of the patellar ligament failed with a midsubstance rupture, and the deeper part with an avulsion through the calcified fibrocartilage or an avulsion fracture. The complex failure characteristics may be attributed to uneven loading, nonuniformity of the structure, and specific anatomical location. Subchondral bone beneath femoral and tibial insertions seems to be weaker than the transitional zone between soft tissue and hard bone at the enthesis. The overall inferior structural quality of a ruptured ligament has to be taken into account when parts of the original structure are used for suturing or reconstruction.

Animals↗
PubMed1996

Validation of retroviral detection for rodent cell-derived products and gene therapy applications.

The availability of sensitive assays for detecting infectious murine retroviruses has become critical for the development and acceptance of a number of biopharmaceuticals, including monoclonal antibody-derived products and gene therapy vectors. Comparative studies demonstrated that the PG4 S+L- retrovirus infectivity test routinely yields higher titres than the mink cell test for xenotropic, amphotrophic and MCF murine retroviruses. A validation study for the PG4 S+L- assay demonstrated very good linearity (r2 of 0.95 to 0.99), reproducibility within a study (+/-0.35 log10 units), and precision between tests (+/-0.45 log10 units). Interference (or selectivity) in the presence of a non-specific antibody was insignificant (less than 0.2 log10 units). Sensitivity levels established from measurements as virus titres approach zero demonstrated a threshold value of 2-3 focus forming units (FFU)/ml. Two methods for increasing assay sensitivity were used including: (i) increased product samplings combined with a Poisson distribution analysis, and (ii) a 14-day co-cultivation with Mus dunni cells. Each of these methods was shown to increase sensitivity by at least one log10 unit. Murine retroviruses may also be detected by a less sensitive immunofluorescence assay (IFA) using specific monoclonal antibodies; this assay is essential for detecting certain recombinant ecotropic MuLVs. In summary, murine retroviral detection ranked by sensitivity is mink S+L- < IFA with monoclonal antibodies < PG4 S+L- < Mus dunni co-cultivation followed by PG4 S+L-.

Animals↗
PubMed1995

Transient local presence of nerve fibers at onset of secondary ossification in the rat knee joint.

In view of recent evidence that nerves may be involved in bone formation, the present study examines the local occurrence of axons at the onset of secondary ossification center formation in the knee region of developing rats. Radiographic and histological examination showed that secondary ossification center formation commenced at day 10. At day 15 the epiphyseal ossification had reached a relatively mature state. As seen by light microscopy, cartilage canals first appeared at day 5, reaching the epiphyseal center by day 9. Axons exhibiting a neurofilament-like immunoreactivity emerged from the perichondrial plexa into the cartilage canals. Many calcitonin gene-related peptide (CGRP)-immunoreactive axons were found in the canals, as well as in the perichondrium. Axons with tyrosine hydroxylase-like immunoreactivity were not found in the canals, but such fibers occurred in relation to blood vessels at other sites. The canal-related axons disappeared between days 13 and 15, and the canals themselves did not persist beyond bone formation. As seen in the electron microscope, an individual canal contained 3-10 unmyelinated Schwann cell-enclosed axons with diameters of 0.1-2.0 microM. These observations show that putative sensory unmyelinated axons with CGRP-and SP-like immunoreactivity are transiently present during initiation of bone formation in developing epiphyses. Whether there is a causal relation between transient innervation and osteogenesis remains to be determined.

Animals↗
PubMed1995

Synovial reaction and concentrations of proteoglycan fragments in joint fluid after intraarticular knee injuries.

In patients with pathology to cruciate ligaments, menisci and cartilage and in some patients with symptomatic knees without gross intraarticular changes, proteoglycan fragment concentrations in joint fluid and inflammatory reaction of the synovium were related to the cartilage condition. There was a weak positive correlation between increased concentrations of proteoglycan fragments in joint fluid and the degree of cartilage degeneration, indicating higher concentrations in knees with more advanced cartilage destruction, but there was no correlation to the synovial reaction at histological inspection. However, in most knees the synovial tissue was infiltrated by inflammatory cells. Symptomatic knees free from gross intraarticular pathology showed similar synovial changes and concentrations of proteoglycan fragments in joint fluid as knees with intraarticular pathology and obvious cartilage degeneration. The complex process of proteoglycan synthesis, release, degradation, and clearance from joint fluid apparently caused the weak or absent correlations between this 'marker' protein and the degree of synovitis and arthrosis stage.

Adolescent↗
PubMed1995

An unusual case of vascular abnormality mimicking a lateral meniscal cyst.

An unusual case of a vascular abnormality mimicking a lateral meniscal cyst is reported. The patient was a 31-year-old active sportsman who presented with intermittent pain over the lateral aspect of the left knee joint line, occurring only during activities involving twisting motions such as playing soccer. He did not experience local tenderness or swelling, clicking, locking, or giving way. The magnetic resonance imaging, which was done after a diagnostic arthroscopy with normal intra-articular findings, showed a cyst formation of approximately 4-mm diameter adjacent to the lateral meniscus periphery, but no meniscal tissue degeneration. Exactly at the preoperatively marked site of most intensive pain sensation during twisting motions, surgical exposure showed a venous-aneurysm-like tumor, which was removed. The operation resulted in complete relief of symptoms and undisturbed sporting activities including soccer.

Adult↗
PubMed1995

Instrumented analysis of the pivot shift phenomenon after reconstruction of the anterior cruciate ligament.

The pivot shift was analysed using an electrogoniometer linkage (OSI, CA, USA) in 27 patients 18 to 24 months after reconstruction of the anterior cruciate ligament (ACL). The static passive AP-displacement of the tibia was also measured by a laxity tester in 20 degrees of knee flexion with a load of 90N. All patients had a positive pivot shift on manual examination before surgery. At follow-up 18 patients had normal subjective knee function according to the Lysholm score and 18 patients had returned to their preinjury, competitive activity level. Only three patients had a positive pivot shift on manual testing. In contrast a pivot shift curve was registered with the electrogoniometer in 18/27 in the operated knee. Their mean maximum tibial translation in the operated knee during the pivot shift test was 8.1 +/- 4.3 mm. In 10 of these patients a pivot shift-like motion pattern was recorded also in the non-operated knee. Generally patients with passive sagittal A-P displacement difference of the tibia of > +2 mm in comparison to the non-operated knee also had positive instrumented pivot shift tests. In six control subjects without previous knee injury the electrogoniometer revealed no pivot shift curve and the mean maximum sagittal translation was only 3.4 +/- 1.3 mm. It seems that pathologic knee motions can be provoked manually in many patients two years after reconstruction of the ACL in spite of a generally good clinical result. In some patients also the non-operated knee shows a pathologic motion pattern that could not be demonstrated in normal subjects. Computerized registration of the pivot shift phenomenon was more sensitive than ordinary manual testing. These findings are in line with results previously found in vitro.

Adult↗
PubMed1995

Femoral stiffness after osteosynthesis of a subcapital osteotomy in osteoporotic bone: an in-vitro comparison of nine fixation methods.

Restitution of normal bone mechanics after osteosynthesis of a proximal femoral fracture in the elderly is assumed to be a prerequisite for optimal healing. To find the most appropriate fixation device for this purpose, the stiffness of 79 cadaver femora from donors with a history of osteoporosis was measured during axial loading before and after a subcapital osteotomy stabilized with one of nine different osteosynthesis devices. Only an osteotomy stabilized with an experimental device consisting of 2 von Bahr screws (Ericsson AB, Göteborg, Sweden) supported by acrylic cement gave similar mean values as the intact femur. A femur stabilized with the Deyerle device (Biomet, Bridge End, Wales, U.K.), with cannulated screws type Uppsala (Olmed AB, Uppsala, Sweden), or with von Bahr screws had an approximately 20-30% lower stiffness than tested intact. However, these devices provided a higher femoral stiffness than the hook-pin technique type LiH (Söderström AB, Gothenburg, Sweden), cannulated screws (Smith & Nephew, Memphis, TN, U.S.A.), a sliding screw plate (Smith & Nephew), a compression screw with variable length (Biomet), or an experimental screw providing expansion and compression. Despite attempted compression of the osteotomy by some of the devices, all of the commercially available devices resulted in a decrease of femoral stiffness after fixation, which may adversely influence the healing of femoral neck fractures in the elderly. Only a combination of screws and bone cement resulted in normal femoral stiffness, probably because of better device anchorage in the osteoporotic cancellous bone. However, this combination might have the potential risk of vascular damage.

Aged↗
PubMed1995

Sagittal plane translation of the tibia in anterior cruciate ligament-deficient knees during commonly used rehabilitation exercises.

It may be assumed that exercises that provoke high sagittal plane knee translations also induce high stresses on an anterior cruciate ligament substitute and, therefore, these exercises should be limited during the first months after reconstruction. In 18 patients with unilateral anterior cruciate ligament deficiency, sagittal plane knee translations were measured with a goniometer linkage system during common activities. The largest translations were found during low-speed isokinetic exercises. Further, isokinetic and isometric exercises on the Cybex-II dynamometer provoked in more than 40% of the patients larger translations on the injured than on the healthy knee. However, isometric exercises without distally applied load only provoked small translation. During bicycling, translations increased with increasing resistance similarly in both limbs. Except for walking downstairs, load-bearing exercises, such as sitting down and standing up from a chair and walking upstairs, only produced negligible amounts of tibial translation. In conclusion, during the early phase after anterior cruciate ligament reconstruction, activities such as bicycling and some weight-bearing exercises seem to be more recommendable than low-speed isokinetic exercises, isometric contractions at a low knee flexion angle with distally applied load or walking downstairs.

Adult↗
PubMed1995

Early roentgenological grading of femoral shortening is correlated to the late outcome after femoral neck fractures.

Using orthoradiography, the distance between the centre of the femoral head and the intercondylar notch was assessed at regular intervals in 144 patients who were followed for a 2-year period after osteosynthesis of a femoral neck fracture. Late complications, such as segmental collapse and non-union, occurred in 27% of the patients. The degree of femoral shortening was significantly correlated to the incidence of late complications. At 1 month, femoral shortening of more than 5 mm was observed in 85% of patients who developed late complications, and in only 5% of patients without such complications. Thus, the observation of a shortening of more than 5 mm predicted a greater than 6-fold increase of the incidence of late complications. The prognostic accuracy of this observation 1 month after treatment was 92%.

Adult↗
PubMed1994

Fingerprinting reveals gamma-ray induced mutations in fungal DNA: implications for identification of patent strains of Trichoderma harzianum.

We have analyzed different patent strains and gamma-ray induced mutants of Trichoderma harzianum by DNA fingerprinting and PCR fingerprinting (RAPD). Applying wild-type phage M13 DNA, with the oligonucleotides (CT)8 and (GTG)5 as probes for hybridization, as well as the oligonucleotides GGCATCGGCC, (GTG)5, (CAC)5 and the M13 sequence GAGGGTGGCGGTTCT as primers in PCR, we were able to obtain different and discriminative fingerprint patterns for all strains and mutants investigated. Irradiation of fungi led to mutations which resulted in new fingerprint patterns. Consequently, irradiation-induced mutants can be clearly distinguished from the original wild-type isolates by genomic fingerprinting which is of importance for the patent protection of fungal strains. Sequencing of the ITS-1 and ITS-2 regions of the rDNA gene complex revealed the same sequence for all mutant strains and the original wild-type strain.

Base Sequence↗