Biomedical subjects

R Dorotka

Publications and source records attributed to R Dorotka.

12 recordsLinked to original sources

PubMed2006

A tissue engineering approach to meniscus regeneration in a sheep model.

OBJECTIVE: Regeneration of the meniscal tissue occurs to a limited extent, and the loss of meniscal tissue leads to osteoarthritis. A new biomaterial consisting of hyaluronic acid and polycaprolactone was used as a meniscus substitute in sheep to evaluate the properties of the implant material with regard to size, biomechanical stability, tissue ingrowth, and integration. METHODS: Eight sheep (right stifle joints) were treated with three total and three partial meniscus replacements while two meniscectomies served as empty controls. The animals were euthanized after 6 weeks. The specimens were assessed by gross inspection and histology, and compared with the nonoperated left joints. RESULTS: The surgical technique was found to be feasible. The implants remained in position, did not tear, and showed excellent tissue ingrowth to the capsule. Tissue integration was also observed between the original meniscus and the implant. However, graft compression and extrusion occurred. The histological investigation revealed tissue formation, cellular infiltration and vascularization. Cartilage degeneration was more severe in the operated joints. CONCLUSION: The present study shows promising results concerning the qualities of this biomaterial with regard to implantation technique, stability and tissue ingrowth.

Adjuvants, Immunologic↗

PubMed2005

Three-year clinical outcome after chondrocyte transplantation using a hyaluronan matrix for cartilage repair.

Repair of articular cartilage represents a significant clinical problem and although various new techniques - including the use of autologous chondrocytes - have been developed within the last century the clinical efficacy of these procedures is still discussed controversially. Although autologous chondrocyte transplantation (ACT) has been widely used with success, it has several inherent limitations, including its invasive nature and problems related to the use of the periosteal flap. To overcome these problems autologous chondrocytes transplantation combined with the use of biodegradable scaffolds has received wide attention. Among these, a hyaluronan-based scaffold has been found useful for inducing hyaline cartilage regeneration. In the present study, we have investigated the mid-term efficacy and safety of Hyalograft C grafts in a group of 36 patients undergoing surgery for chronic cartilage lesions of the knee. Clinical Outcome was assessed prospectively before and at 12, 24, and 36 months after surgery. No major adverse events have been reported during the 3-year follow-up. Significant improvements of the evaluated scores were observed (P < 0.02) at 1 year and a continued increase of clinical performance was evident at 2 and 3 years follow-up. Patients under 30 years of age with single lesions showed statistically significant improvements at all follow-up visits compared to those over 30 with multiple defects (P < 0.01). Hyalograft C compares favorably with classic ACT and is particularly indicated in younger patients with single lesions. The graft can be implanted through a miniarthrotomy and needs no additional fixation with sutures except optional fibrin gluing at the defect borders. These results suggest that Hyalograft C is a valid alternative to ACT.

Adult↗

PubMed2005

Repair of articular cartilage defects treated by microfracture and a three-dimensional collagen matrix.

The objective of our study was to evaluate the behavior of ovine chondrocytes and bone marrow stromal cells (BMSC) on a matrix comprising type-I, -II, and -III collagen in vitro, and the healing of chondral defects in an ovine model treated with the matrix, either unseeded or seeded with autologous chondrocytes, combined with microfracture treatment. For in vitro investigation, ovine chondrocytes and BMSC were seeded on the matrix and cultured at different time points. Histological analysis, immunohistochemistry, biochemical assays for glycosaminoglycans, and real-time quantitative PCR for collagens were performed. The animal study described here included 22 chondral defects in 11 sheep, divided into four treatment groups. Group A: microfracture and collagen matrix seeded with chondrocytes; B: microfracture and unseeded matrices; C: microfracture; D: untreated defects. All animals were sacrificed 16 weeks after implantation, and a histomorphometrical and qualitative evaluation of the defects was performed. The in vitro investigation revealed viable cells up to 3 weeks; chondrocytes had a predominantly round morphology, produced glycosaminoglycans, and expressed both collagen markers, whereas BMSC stained positive for antibodies against type-II collagen; however, no mRNA for type-II collagen was amplified. All treatment groups of the animal model showed better defect filling compared to untreated knees. The cell-seeded group had the greatest quantity of repair tissue and the largest quantity of hyaline-like tissue. Although the collagen matrix is an adequate environment for BMSC in vitro, the additionally implanted unseeded collagen matrix did not increase the repair response after microfracture in chondral defects. Only the matrices seeded with autologous cells in combination with microfracture were able to facilitate the regeneration of hyaline-like cartilage.

Animals↗

PubMed2005

Marrow stimulation and chondrocyte transplantation using a collagen matrix for cartilage repair.

OBJECTIVE: The purpose of the study was to determine whether the implantation of a scaffold would facilitate cartilage repair after microfracture in sheep over a period of 12 months. Furthermore, we investigated the effect of additional autologous cell augmentation of the implanted constructs. METHODS: Two chondral defects were produced in the medial femoral condyle of sheep without penetrating the subchondral bone. Twenty-seven sheep were divided into the following groups: seven served as untreated controls (Group 1), microfracture was created in 20 animals, seven of them without further treatment (Group 2), in six sheep the defects were additionally covered with a porcine collagen matrix (Group 3), and in seven animals the matrix was augmented with cultured autologous chondrocytes (Group 4). After 4 (11 sheep) and 12 months (16 sheep), the filling of the defects, tissue types, and semiquantitative scores were determined. RESULTS: The untreated defects revealed the least amount of defect fill. Defects treated with microfractures achieved better defect fill, while the additional use of the matrix did not increase the defect fill. The largest quantity of reparative tissue was found in the cell-augmented group. Semiquantitative scores were best in the cell-augmented group. CONCLUSION: Microfracture treatment was observed to enhance the healing response. The implantation of a cell-seeded matrix further improved the outcome. The implantation of a collagen matrix alone did not enhance repair. Autologous cell implantation appears to be a very important aspect of the tissue engineering approach to cartilage defects.

Animals↗

PubMed2004

[Mid-term results of autologous chondrocyte transplantation in knee and ankle. A one- to six-year follow-up study].

BACKGROUND: The reimplantation of autologous chondrocytes is a new technique in reconstruction of cartilage defects; initial results achieved with this technique have been promising. In an arthroscopic procedure, scales of cartilage are obtained from intact cartilage. The chondrocytes are then multiplied in special laboratories. A few weeks later, in a second procedure, the cartilage defect is filled with the cell suspension and closed with a flap of periosteum. METHOD: At our department, autologous chondrocyte transplantation (ACT) has been used in 10 patients since 1996, in 6 cases in the knee joint, and in 4 cases in the ankle joint. The mean age of the patients was 30 years. The mean size of the defect was 4 cm(2). In 4 patients, a parallel surgical procedure was required at the time of removal. RESULTS: The mean duration of follow-up was 21/2 years. Six patients had good to excellent results, 3 patients had moderate results, and one patient a poor result. The modified Cincinnati rating scale was improved from 2.4 to 7.1 points, and the Lysholm score from 59.2 to 86.6 points. The AOFAS score for ankle joints had improved from 33 to 76. CONCLUSION: We were able to show that ACT achieves improvement in the knee as well as ankle joint in the majority of patients. ACT appears to be a promising therapeutic concept for both joints.

Adolescent↗

PubMed2003

Effects of extracorporeal shock waves on human articular chondrocytes and ovine bone marrow stromal cells in vitro.

INTRODUCTION: We investigated the effects of extracorporeal shock waves on cytotoxicity and on the proliferation of human chondrocytes and ovine bone marrow stromal cells. MATERIALS AND METHODS: Isolated cells were cultured to confluence, and 500 shock waves were applied at energy flux densities of 0, 0.02, 0.06, and 0.17 mJ/mm(2 )for the cytotoxicity assay. The same energies at 100, 500, and 1000 impulses were used for the proliferation assay. RESULTS: Although bone marrow stromal cells revealed a dose- and impulse-dependent increase in the proliferation rate, no significant differences were found. Chondrocytes had less proliferative potential than untreated control groups. In the experimental set-up using 1000 impulses, proliferation was even higher in the control group. Both types of cells revealed a dose-dependent increase in cytotoxicity in the lactate dehydrogenase (LDH) assay. CONCLUSION: As femoral head necrosis, osteochondritis dissecans, and similar disorders are increasingly treated with shock waves, their effect on human cartilage and chondrocytes deserves attention. We recommend further in vitro experiments with bone marrow stromal cells, as the latter might play an important role in the presumed multifactorial osteogenetic mechanism of shock waves due to their pluripotent character.

Animals↗

PubMed2003

[Influence of nocturnal surgery on mortality and complications in patients with hip fractures].

UNLABELLED: SUBJECT OF INVESTIGATION: The appropriate time of day for surgery of hip fractures and the question of whether surgery should be performed at night are controversial. We therefore investigated the influence of the time of day on mortality and complication rates in surgery for hip fractures. METHOD: A total of 170 persons were included in the study with 128 operations being performed during the day and 42 at night, after 9 p.m. All patients were operated as early as possible. Patients were randomly assigned to groups. The recorded data were mainly demographic, perioperative and those concerning the patient's history. Mortality and complication rates 6 months after surgery were compared. RESULTS: The two groups were largely homogeneous. Patients operated on at night had a non-significantly higher mortality rate. Mortality was highest in those operated on between 9 and 10 p.m. Of those who underwent surgery after midnight, no patient died. No differences were registered with regard to complications. The team of surgeons and anesthetists was equally qualified in both groups. CONCLUSIONS: Given a medical team with equal qualifications and size, we consider nocturnal surgery for hip fractures to be as appropriate as surgery during the day.

Aged↗

PubMed2003

The influence of immediate surgical treatment of proximal femoral fractures on mortality and quality of life. Operation within six hours of the fracture versus later than six hours.

We compared the mortality and outcome of 182 patients with proximal fractures of the femur after immediate and delayed surgical treatment. Seventy-nine patients were operated upon within six hours of the fracture (group 1) and 103 patients were operated upon after this period of time (group 2). At six months follow-up, group 1 had a significantly lower mortality rate. There was a good outcome in both groups with no differences in the outcome. Neither surgical nor anaesthetic factors appeared to have influenced mortality. The subdivision of groups revealed that patients operated on within 24 hours had a better outcome than those whose surgery was delayed. Although there may have been a bias, as patients were not randomly assigned to immediate or delayed surgical treatment, the data suggest that early stabilisation may be associated with a lower mortality rate. Even with pre-clinical delays of more than six hours early treatment should still be attempted, as better results seem to be achieved after 24 hours compared to a later time in our patients.

Adult↗

PubMed2002

[3D-navigated high energy shockwave therapy and axis correction after failed distraction treatment of congenital tibial pseudarthrosis].

The treatment of congenital tibial pseudarthrosis using a distraction procedure as described by Ilizarov is a standard surgical intervention. Nevertheless, there are problems in achieving bony stability in about 10% of cases even after repeated surgery as reported by Lammens et al. (2000). Traub et al. (1999) found a rate of 50% amputations in 33 cases treated since 1927. To prevent an Ilizarov procedure from resulting in a delayed union or nonunion, Paley et al. (1992) recommended autografting immediately after distraction. Based on the good results in the stimulation of osteogenesis in adults, we started to treat delayed bone union following distraction treatment with high-energy shock wave therapy also in children. In patients suffering from congenital tibial pseudarthrosis with a deviation of the bony axis, we combine this surgery-substituting therapy with fixation of a Taylor spatial frame in order to correct the axis. Using this new method of treatment, we were able to achieve stability in four children who previously had had nonunion even after multiple surgical interventions.

Adolescent↗

PubMedDate not supplied

[Periprosthetic femoral fractures in total hip prosthesis implantation. Functional and radiological comparison between plate osteosynthesis and proximal femur replacement].

AIM: Clinical and radiological examinations were performed to compare plate osteosynthesis (group 1) with replacement of the proximal femur by tumor prosthesis (group 2) in patients with ipsilateral femoral fractures around a hip prosthesis. METHOD: Of 24 consecutive patients with 25 fractures, nine had died and one could be contacted by telephone leaving 14 hips (in one case only recent X-rays were available) for final review (nine patients from group 1; five from group 2). RESULTS: At the time of examination four patients of group 1 were using one cane or were walking without any support, all patients of group 2 needed one or two crutches. In 5 of 9 patients in group 1 and in 4 of 5 in group 2 a firm fit of the prosthesis was observed. CONCLUSION: Group 1 achieved better clinical results in postoperative mobility, whereas femoral replacement showed better radiological results. Survival of patients with tumor prostheses was considerably superior to that of patients with plate osteosynthesis.

Activities of Daily Living↗

PubMedDate not supplied

[Evaluating rehabilitation progress by measuring thigh circumference].

QUESTION: Thigh girth measurements have been widely used to quantify rehabilitation progress following knee surgery, but the correlation between thigh girth and other functional measures has not been investigated. This study intended to investigate whether such a correlation exists. METHODS: 15 women with bilateral osteoarthrosis of the knee participated in this study. Isokinetic knee extensor strength, thigh girth and body mass were measured immediately before, then at six weeks and six months following cementless total knee arthroplasty. RESULTS: The involved side showed clear pre-operative isokinetic knee extensor strength deficits, and slight reductions in thigh girth. Post-operatively, mean strength deficits were reduced, whereas differences in mean thigh girth became lager. Although thigh girth changes correlated well with body mass, they did not correlate with knee extensor strength. CONCLUSION: Changes in thigh girth are mainly due to changes in body mass. Thigh girth measurement is of no use for the quantification of the rehabilitation progress in total knee arthroplasty.

Aged↗

PubMedDate not supplied

[Patellofemoral pain syndrome in young men compared to a normal population exposed to the same physical strain].

AIM: The causes of the patellofemoral pain syndrome, especially in young patients, continue to be largely unknown. The purpose of the study was to determine the extent to which weight and activities that impose a strain on the knee influence the occurrence of patellofemoral pain in young, physically active men. METHOD: 248 soldiers on mandatory military service were included in the study. 133 persons had pain in the knee prior to or during military service while 115 persons had no symptoms in the knee. Anthropometric data and patient history were recorded for all individuals. This was followed by clinical examination. RESULTS: Age distribution and body mass index were identical in both groups. However, significantly more subjects in the group with pain prior to military service had been active sportsmen while a significantly larger number of normal individuals had had jobs that strained the knees. The greatest difference, however, was seen in the number of previous injuries. These were much more common in the group that had pain and the injuries most commonly were contusions. CONCLUSION: It is well known that previous injuries and sports favor the emergence of patellar pain. However, persistent strain on the knee at work appears to be less commonly associated with this symptom. The individual's body-mass index was of no importance in this context.

Adolescent↗