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Biomedical subjects

K Messner

Publications and source records attributed to K Messner.

At least 19 recordsLinked to original sources
PubMed2000

Long-term results of meniscus repair and meniscectomy: a 13-year functional and radiographic follow-up study.

This study investigated the long-term outcome of common meniscus treatment (meniscectomy, repair). A consecutive series of 30 patients with open meniscus repair were compared retrospectively to 30 patients who had an arthroscopic partial or subtotal meniscectomy. The groups were matched according to sex, age, meniscus lesion, and follow-up time. The patients were aged 13-43 years at the time of operation; all had intact cruciate ligaments, and none had had previous surgery on the knee. Patients were reexamined at a mean of 13 years after the operation. In addition, for a subgroup of 22 matched pairs, data were available from a 7-year follow-up. Four of the repaired menisci did not heal, and another three reruptured during the 13-year follow-up; these menisci were all excised (23%). Meniscal remnant surgery was needed in 6 cases (20%) after initial meniscectomy. At the 13-year follow-up there was no difference between the groups in knee function, subjective complaints, or manual findings. Almost 90% of the patients in both groups had no knee problems during daily activities. At the late follow-up radiographic signs for bone spurs, sclerosis, or flattening of the femoral condyle were found in around half of the cases in each group. Three patients (10%) with initial repair and 8 (27%) with meniscectomy had minor joint space reduction, but no patient had more severe radiographic changes. After 7 years (subgroup) joint space reduction was more common after initial meniscectomy than after repair (P < 0.05). After 13 years the incidence and severity of arthrosis did not differ significantly between the two groups, even when only the successful repairs were compared to meniscectomy (P = 0.06).

Adult↗
PubMed2000

Estrogen-dependent tensile properties of the rabbit knee medial collateral ligament.

The influence of oophorectomy or continuous administration of estradiol on the tensile properties of the rabbit knee medial collateral ligament was investigated. Young postpubertal female New Zealand white rabbits were either oophorectomized or underwent a sham operation. The sham-operated animals received in addition a daily dosage of 4 mg 17beta-estradiol. After 5 months the animals were killed, and the material properties of the bone-ligament-bone complex in one knee were determined using a material testing machine and video system, and compared to non-treated control animals. There was no difference in elastic modulus between the groups. However, the ligaments from low-dose estrogen-treated animals had a smaller cross-sectional area and a higher ultimate tensile strength than those from controls or oophorectomized rabbits (P<0.04-0.0003).

Animals↗
PubMed2000

Simultaneous changes in bone mineral density and articular cartilage in a rabbit meniscectomy model of knee osteoarthrosis.

OBJECTIVE: It was hypothesized that increased bone mineral density of the medial proximal tibia would precede or coincide with the development of more severe cartilage changes after meniscectomy. METHODS: In a rabbit knee model, mineral density of subchondral bone and changes of articular cartilage were monitored 13 to 40 weeks after medial meniscectomy or a sham operation. RESULTS: Both procedures resulted in a decrease of bone mineral density, especially of the medial proximal tibia, which persisted up to 40 weeks (P< 0.02-0.0007). Meniscectomy induced cartilage changes typical for osteoarthrosis (P< 0.009), which progressed over time on the posterior aspect of the medial tibial plateau (P< 0.009), which is physiologically covered by the meniscus, but the procedure also induced iatrogenic changes which were located mainly on the anterior aspect of the concerned compartment, and which did not progress or develop to osteoarthrosis. CONCLUSIONS: The data suggest that the cartilage changes after meniscectomy in this animal model are caused by the surgical trauma, subsequent limb misuse, and altered load distribution, and initially associated by a decrease not an increase in bone mineral density of the proximal tibia. Moreover, the cartilage changes progressed without a simultaneous increase of the bone mineral density at corresponding sites.

Animals↗
PubMed1999

Extracellular lipid peroxidation of selective white-rot fungus, Ceriporiopsis subvermispora.

Ceriporiopsis subvermispora is capable of decomposing lignin without penetration of enzymes into wood cell walls. To elucidate the mechanism of lignolysis at a site far from enzymes, peroxidation of low molecular mass compounds produced by this fungus was analyzed. C. subvermispora produced free 9,12-octadecadienoic, 9-octadecenoic, 11-octadecenoic, hexadecanoic and octadecanoic acids, predominantly at an early stage of cultivation on wood meal cultures. In prolonged cultivation period after 2 weeks, the amount of intact fatty acids decreased with increasing organic hydroperoxide and TBARS production. These results suggest that lignin degradation by C. subvermispora is related to extracellular lipid peroxidation.

Basidiomycota↗
PubMed1999

Maturation-dependent durability of spontaneous cartilage repair in rabbit knee joint.

The spontaneous healing of osteochondral defects in the knee joints of immature rabbits within the first 12 weeks after surgery showed a faster filling and earlier tissue specialization than in adult animals. The purpose of the present study was to investigate whether the better short-term quality of spontaneous repairs in immature animals lasted over a period of 48 weeks. A full-thickness osteochondral defect was created on the medial femoral condyle in both knees of 10 young, 10 adolescent, and 10 adult rabbits. Equal numbers of animals were evaluated after 24 and 48 weeks. At both time intervals, bonding to adjacent cartilage and proteoglycan content of the matrix were better in the repairs of young than in adult animals. Repairs in the former had cellularity similar to the adjacent cartilage and were composed of 90% hyaline-like cartilage, which did not decrease with time. In contrast, repairs in older animals formed less hyaline-like cartilage and had a lower cellularity than the adjacent cartilage. However, the surface of the repaired tissue was similarly disrupted in all age groups, and the mechanical properties remained inferior to adjacent or normal cartilage. Repairs in older animals showed signs of degeneration with time. The initial better repair quality in a young, growing animal remained up to 48 weeks when the animal had already reached maturity, indicating that successful initial promotion of cartilage repair may even lead to better results in the long term. However, it has to be pointed out that the morphologically good repairs with hyaline-like cartilage appearance, normal cellularity, and durability of up to 48 weeks were unable to reestablish and maintain a cartilage-like mechanical function.

Age Factors↗
PubMed1999

[Cartilage replacement operation using pre-cultured cells].

Clinical results using transplantation of precultivated autologous chondrocytes for treatment of circumscribed chondral injuries in the knee joint have been presented 1994. The quality of this method for clinical use can not be evaluated at the moment since controlled randomized trials comparing this method with bone drilling, use of periostal flaps or conservative treatment do not exist. According to recent experimental results, techniques using precultivated cells, growth factors and different scaffolds for repair of limited cartilage defects are not satisfactory yet, and it is unproven whether these methods are superior to simple bone-drilling. Use of precultivated cells and growth factors might nevertheless have a potential in the future, when we have learned to use them under optimized conditions. Unless these conditions have been developed and proven to reliably improve cartilage repair above previous methods, in a clinical case the treatment should be chosen which is the least invasive.

Animals↗
PubMed1999

Meniscal regeneration or meniscal transplantation?

Owing to the initial necrosis to which any freely transplanted biological graft is subjected, meniscus transplantation is based on similar principles to meniscal regeneration. Both methods rely on repopulation of extrinsic cells of the graft. In the former procedure a biological matrix (meniscus, tendon, fatpad) is used as graft (scaffold), whereas in meniscal regeneration commercially available resorbable or non-resorbable scaffolds are implanted. However, the cellular (re)population and (re)vitalization process is deleterious rather than beneficial for the function of the graft as the remodelling of the tissue leads to shrinkage and narrowing of the implant. In addition, improper fixation and subsequent elongation of the anterior and posterior bony attachments leads to peripheral graft dislocation, loss of the load distribution function, and subsequently to cartilage degeneration. Hence, meniscus transplantation or regeneration faces two major problems: 1) remodelling of graft to inferior tissue properties after allograft transplantation, or lacking establishment of normal tissue properties after use of biological matrixes other than the meniscus (fatpad, tendon), or commercially available matrixes; 2) improper fixation with elongation of the anterior and posterior attachments. Furthermore, use of allografts incorporates the risk for disease transmission. Today we are unable to control these problems, and therefore the concept of meniscal replacement does not work yet. Further research is necessary to control remodelling and improve fixation to make this procedure a successful one in the future.

Biomechanical Phenomena↗
PubMed1999

Future research in meniscal replacement.

To study the remodelling process after meniscus replacement and to learn how to control it will be a key topic for future research. Not enough is known about the importance of precision in meniscal fixation and how to make the insertions as strong as in the normal meniscus. Methods to measure load-distribution, mechanical properties of the graft and status of the cartilage should be developed. A number of different auto- and allografts have been shown to heal and revascularize, but whether the grafts are functioning is not known. Meniscal scaffolds, which can be used for replacement of partial meniscal loss, need to be tested. Scaffolds and tissue engineering will be the subject of intensive research in the future.

Cryopreservation↗
PubMed1999

Rat model of Achilles tendon disorder. A pilot study.

Three-month-old male rats were subjected 3 times weekly for 1 h to eccentric exercise of one triceps surae muscle (30 stimulations/min) under general anesthesia in order to induce Achilles tendon disorder corresponding to paratenonitis and tendinosis in man. Net muscle work during the sessions ranged between 0.67 and 4.37 mJ (mean 1.72, SD 0.77). After 9 and 13 sessions, respectively, 2 rats started to show gait alterations during the functional test which was performed 2-3 times weekly. These rats were killed after additional sessions which showed a worsening of the limp. The other trained rats and controls did not limp and were killed after 7-11 weeks. Histologic evaluation of the Achilles tendons from the exercised limb showed in the majority of the cases hypervascularization, increased number of nerve filaments and increased immunoreactivity for substance P and calcitonin gene-related peptide. The tendons from the nonstimulated limb looked normal. The distribution of collagen types I and II appeared normal in the tendon and its insertion to the calcaneus. Inflammation of the epi- and paratenon could be provoked in the rat, but tendon changes corresponding to chronic tendinosis did not develop within 11 weeks with the used training regime. The clinical relevance of this model for chronic tendon disease needs to be evaluated further.

Achilles Tendon↗
PubMed1999

Anterior cruciate ligament reconstruction and the long-term incidence of gonarthrosis.

Knee ligament injuries are common in sport. A rupture of the anterior cruciate ligament (ACL) is the most serious of these injuries because it may cause long term disability. In this literature review, the frequency of post-traumatic gonarthrosis is examined. There are few long term prospective studies but a number of retrospective studies with follow-up times between 5 and 20 years have been published. These studies show that radiographic gonarthrosis is significantly increased after all knee injuries compared with the uninjured joint of the same patient. Isolated meniscus rupture and subsequent repair, or partial or total ruptures of the ACL without major concomitant injuries, seem to increase the risk 10-fold (15 to 20% incidence of gonarthrosis) compared with an age-matched, uninjured population (1 to 2%). Meniscectomy in a joint with intact ligaments further doubles the risk of gonarthrosis (30 to 40%), and 50 to 70% of patients with complete ACL rupture and associated injuries have radiographic changes after 15 to 20 years. Thus, an ACL rupture combined with meniscus rupture or other knee ligament injuries results in gonarthrosis in most patients. Ten to 20 years after ACL injury, gonarthrosis often presents as a slight joint space reduction or, occasionally, joint space obliteration (Ahlbäck grades I to II), but is usually not associated with major clinical symptoms. According to the few longitudinal studies, the progress of gonarthrosis is slow, and in some cases the condition seems to remain stable. Time is an important determinant for the degree of gonarthrosis and problems demanding treatment may be encountered only at > 30 years after the initial accident.

Adolescent↗
PubMed1999

Articular cartilage compressive stiffness following oophorectomy or treatment with 17beta-estradiol in young postpubertal rabbits.

BACKGROUND: Changes in estrogen concentrations during adolescence (contraceptives, secondary amenorrhea) may influence cartilage mechanics and therefore its capacity to respond adequately to physical demands. The purpose of this study was to investigate the influence of oophorectomy or continuous administration of estradiol on cartilage compressive properties in an immature animal model. METHODS: Young postpubertal female New Zealand white rabbits were either oophorectomized (n=9) or underwent a sham-operation (n=8). The sham-operated animals received in addition a daily dosage of 4 mg 17beta-estradiol orally starting 3 weeks after surgery until death. After 5 months the animals were killed, and cartilage compressive properties (ramp and creep moduli) were determined at 4 defined knee joint regions by in situ indentation tests. Five age-matched rabbits were used as controls. RESULTS: Femoral cartilage stiffness (ramp and 15-s creep moduli) and thickness in oophorectomized animals were significantly higher than those in controls or estradiol-treated animals (p<0.05 and less), but there was no difference between the latter groups. Tibial cartilage showed less obvious treatment-dependent differences. The cartilage in the medial compartment was thicker than in the lateral one, and femoral cartilage was thinner than tibial cartilage (p<0.00005), irrespective of the treatment. CONCLUSIONS: Oophorectomy during adolescence led to increased femoral cartilage thickness and stiffness. The relevance of these findings for the development of cartilage disease has to be elucidated in the future.

Age Factors↗
PubMed1998

[Current advances in sports-related cartilage research. Meniscus and ligament injuries are associated with increased risk of knee joint arthrosis].

The majority (up to 87%) of patients with meniscus and ligament injuries of the knee develop degenerative radiological changes in a 10-20-year perspective, patients with knee injuries involving several structures being at the greatest risk. A high level of activity has been shown to be a correlate both of repeat injury and the development of osteoarthrosis. However, it has not been determined when or in what proportion of cases such changes result in joint destruction and permanent disability. The incidence of isolated cartilage injuries is low, and it is unclear whether such injuries predispose to osteoarthrosis. No validated method is yet available for the effective treatment of circumscribed or more extensive cartilage injuries, which would be preferable to conservative treatment.

Athletic Injuries↗
PubMed1998

Copper-dependent depolymerization of lignin in the presence of fungal metabolite, pyridine.

Thus far, it has not been recognized that copper complexes are able to depolymerize lignin under physiological conditions of white rot decay. However, we have found that both phenolic and non-phenolic synthetic lignins were intensively depolymerized by Cu(II) and lipid hydroperoxide model compounds in the presence of a metabolite of ligninolytic fungi, pyridine at room temperature in aqueous media. Treatment of 14C-labeled oxygen-prebleached kraft pulp (OKP) by the copper-dependent reaction evidenced effectiveness of this reaction for the delignification of kraft pulps. In contrast to the organic peroxide system, Cu(II)/pyr/H2O2 system was much less effective for the lignin depolymerization. However, treatment of unbleached kraft pulp (UKP) by Cu(II)/H2O2 and Cu(II)/pyr/H2O2 systems demonstrated that the damage of cellulose was suppressed by the coordination of pyridine although high brightness gain was obtained independently of the presence of the coordinator. Spin trapping experiments demonstrated that not hydroxyl radical but superoxide anion is involved in the Cu(II)/pyr/H2O2 system. This finding not only introduces a new concept of non-enzymatic lignin biodegradation by wood-degrading fungi but also presents a new strategy for decomposing lignin and lignin-related compounds by copper complexes and peroxide-producing system.

Biopolymers↗
PubMed1998

Oxidation of phenanthrene by a fungal laccase in the presence of 1-hydroxybenzotriazole and unsaturated lipids.

Phenanthrene, a polycyclic aromatic hydrocarbon, was efficiently oxidized by laccase in the presence of both 1-hydroxybenzotriazole and unsaturated lipids. 73% of initially added phenanthrene was degraded within 182 hours to give phenanthrene-9,10-quinone and 2,2'-diphenic acid as the major products. The system was also able to peroxidize linoleic acid to its corresponding hydroperoxides suggesting the involvement of lipid peroxidation in laccase catalyzed phenanthrene oxidation. Lipid peroxidation by laccase required 1-hydroxybenzotriazole and did not depend on Mn2+ and H2O2 suggesting that the chemical reactions involved differ from those previously reported for manganese peroxidase.

Basidiomycota↗
PubMed1998

The menisci of the knee joint. Anatomical and functional characteristics, and a rationale for clinical treatment.

The menisci and their insertions into bone (entheses) represent a functional unit. Thanks to their firm entheses, the menisci are able to distribute loads and therefore reduce the stresses on the tibia, a function which is regarded essential for cartilage protection and prevention of osteoarthrosis. The tissue of the hypocellular meniscal body consists mainly of water and a dense elaborate type I collagen network with a predominantly circumferential alignment. The content of different collagens, proteoglycans and nonproteoglycan proteins shows significant regional variations probably reflecting functional adaptation. The meniscal horns are attached via meniscal insertional ligaments mainly to tibial bone. At the enthesis, the fibres of the insertional ligaments attach to bone via uncalcified and calcified fibrocartilages. This anatomical configuration of gradual transition from soft to hard tissue, which is identical to other ligament entheses, is certainly essential for normal mechanical function and probably protects this vulnerable transition between 2 biomechanically different tissues from failure. Clinical treatment of meniscal tears needs to be based on these special anatomical and functional characteristics. Partial meniscectomy will preserve some of the load distribution function of the meniscus only when the meniscal body enthesis entity is preserved. Repair of peripheral longitudinal tears will heal and probably preserve the load distribution function of the meniscus, whereas radial tears through the whole meniscal periphery or more central and complex tears may be induced to heal, but probably do not preserve the load distribution function. There is no proof that replacement of the meniscus with an allograft can reestablish some of the important meniscal functions, and thereby prevent or reduce the development of osteoarthrosis which is common after meniscectomy. After implantation, major problems are the remodelling of the graft to inferior structural, biochemical and mechanical properties and its insufficient fixation to bone which fails to duplicate a normal anatomical configuration and therefore a functional meniscal enthesis.

Animals↗