Biomedical subjects

C Perka

Publications and source records attributed to C Perka.

At least 37 records · Page 2Linked to original sources

PubMed2001

Clinical and gait-analytical results of the modified Evans tenodesis in chronic fibulotalar ligament instability.

The present paper describes the medium-term results (mean follow-up period 3.01 years) achieved after surgical stabilisation of 79 patients using modified Evans tenodesis. The follow-up examination included a questionnaire for rating the subjective sense of stability, a clinical examination, stress X-rays, a modified 100-point score according to Zwipp, and kinetic gait analysis. Although joint instability was significantly improved in the radiological stress images, only 73.4% of the patients subjectively rated the stability achieved as excellent or good, compared with satisfactory in 22%, and even poor in 3.8%. In the overall result of the 100-point score, 51.9% of the patients achieved a very good, 35.4% a good, 11.4% a satisfactory, and 1.3% a poor result. Radiologically, an increase in the rate of arthrosis was verified in 17.4%. Significant deteriorations in mobility were observed for the supination. The kinetic gait analysis revealed statistically significant differences compared with the non-operated side for step length (P < 0.05), relative step length (P < 0.05), and in the symmetry of heel-to-toe movement (P < 0.005). The modified Evans repair can restore the mechanical stability of the ankle, but it leads to impaired kinematics of the ankle, with subjective and functional restrictions and radiologically detectable degenerative changes. For this reason, modified Evans tenodesis should only be performed if anatomically orientated stabilisation operations are not possible.

Adolescent↗

PubMed2001

High tibial osteotomy for valgus and varus deformities of the knee.

In 53 patients with a mean age of 38 (17-73) years, 71 high tibial osteotomies were performed. Twenty-three patients had no radiological signs of osteoarthrosis (Ahlbäck grade 0), whereas 26 patients had primary and 22 patients secondary osteoarthritis. Follow-up was 10.5 (5.8-16.6) years. The patients without radiological osteoarthrosis achieved almost exclusively good or very good scores using the Lysholm-Gillquist (96%) and the Insall scale (83%). By contrast, only 29% of the patients with radiological osteoarthritis achieved good or very good scores. Whether the patient had primary or secondary osteoarthrosis was of no influence. Neither was the preoperative axial deviation.

Adolescent↗

PubMed2001

Treatment of stages 2 and 3 giant-cell tumor.

During the period from August 1986 to August 1992, we treated 23 patients with giant cell tumors stage 2 or 3, according to the classification by Campanacci et al.. We analyzed the therapeutic options, complications, local recurrence rate, and functional results after a mean follow-up of 56 months (range 31-89 months). Intralesional resections were performed in 15 and wide resections in 8 patients. The majority of intralesional resections were performed for stage 2 tumors and the majority of en-bloc resections for stage 3 tumors. The overall local recurrence rate was 8.7%, but we observed local recurrence only in intralesional resections. Our experiences suggest that a subtle surgical technique with respect to oncological requirements is the most important element in the avoidance of local recurrence. Stage 2 tumors associated with weight-bearing anatomical structures should be treated with intralesional curettage and bone cement. Stage 3 tumors are limited as to their surgical options and are determined in some cases by their localization and the degree of bone destruction. Wide resections should be reserved mainly for stage 3 tumors.

Adult↗

PubMed2001

Reconstruction of segmental defects during revision procedures of the acetabulum with the Burch-Schneider anti-protrusio cage.

Sixty-three Burch-Schneider rings in 62 patients with segmental or combined defects were followed up after a mean of 5.45 years. The mean Harris hip score was 74.9 points. Aseptic loosening occurred in 3 cases, and septic loosening occurred in 2 cases. All cases of aseptic loosening had Paprosky stage IIIb defects and defects of the posterior column. Radiologic migration analysis showed increased migration with increase in the Paprosky defect stage, defects of the posterior column, and cranial defects. The cage has the lowest migration and loosening rate in cases with medial defects or anterior column defects. Surgical treatment of defects of the posterior column is associated with an increased rate of aseptic loosening, whereas implantation with cranial defects shows a higher migration rate with no significant increase in loosening.

Acetabulum↗

PubMed2001

The use of fibrin beads for tissue engineering and subsequential transplantation.

New biological technologies such as tissue engineering procedures require the transplantation of functionally active cells within supportive carrier matrices. This paper describes a sequential culture procedure for different types of cells. The technique includes the initial preparation of a mixed alginate-fibrin vehicle that guaranteed an initial cell proliferation and differentiation to establish a stable matrix structure, and the subsequent removal of the alginate component prior to transplantation to circumvent the problem of missing bioresorbability. The resulting biodegradable carrier is mechanically stable and promotes further tissue maturation. Chondrocytes, periosteal-derived cells, as well as nucleus pulposus cells were entrapped in fibrin-alginate beads and in fibrin beads. The results indicate a promising technical approach to create stable transplants for reconstructive surgery of cartilage and bone.

Alginates↗

PubMed2000

The influence of transforming growth factor beta1 on mesenchymal cell repair of full-thickness cartilage defects.

To repair full-thickness articular cartilage defects in rabbit knees, we transplanted periosteal cells in a fibrin gel and determined the influence of transforming growth factor beta (TGF-beta) in vitro. Alginate served as a temporary supportive matrix component and was removed prior to transplantation. The defects were analyzed macroscopically, histologically, and electron microscopically, and evaluated with a semi-quantitative score system. Periosteal cell transplants showed a chondrogenic differentiation, which results in the development of embryonic-like cartilage tissue after 4 weeks and complete resurfacing of the patellar groove after 12 weeks. In the control groups, no repair was observed. Under the influence of TGF-beta1 we observed a reduction of the cartilage layer, whereas the osteochondral integration and the zonal architecture were improved. Periosteal cell-beads are stable cartilage transplants and have stiffness and elasticity enough for easy and sufficient transplant fixation. Further investigations are necessary to optimize the application of TGF-beta1 for cartilage repair.

Alginates↗

PubMed2000

Matrix-mixed culture: new methodology for chondrocyte culture and preparation of cartilage transplants.

For cartilage engineering a variety of biomaterials were applied for 3-dimensional chondrocyte embedding and transplantation. In order to find a suitable carrier for the in vitro culture of chondrocytes and the subsequent preparation of cartilage transplants we investigated the feasibility of a combination of the well-established matrices fibrin and alginate. In this work human articular chondrocytes were embedded and cultured either in alginate, a mixture of alginate and fibrin, or in a fibrin gel after the extraction of the alginate component (porous fibrin gel) over a period of 30 days. Histomorphological analysis, electron microscopy, and immunohistochemistry were performed to evaluate the phenotypic changes of the chondrocytes, as well as the quality of the newly formed cartilaginous matrix. Our experiments showed that a mixture of 0.6% alginate with 4.5% fibrin promoted sufficient chondrocyte proliferation and differentiation, resulting in the formation of a specific cartilage matrix. Alginate served as a temporary supportive matrix component during in vitro culture and can be easily removed prior to transplantation. The presented tissue engineering method on the basis of a mixed alginate-fibrin carrier offers the opportunity to create stable cartilage transplants for reconstructive surgery.

Alginates↗

PubMed2000

Subtrochanteric corrective osteotomy for the endoprosthetic treatment of high hip dislocation. Treatment and mid-term results with a cementless straight stem.

Total hip arthroplasty is problematical in the case of high dislocation. To reposition the hip, a femoral shortening osteotomy is necessary in order to prevent damage to the neurovascular structures. This paper describes the implantation of a cementless straight stem in 15 patients using a simple technique with a simultaneous, derotating and shortening osteotomy. Femur fractures, pseudoarthroses, stem loosening, paresis and deep infections were not found. One socket loosening was revised. Fourteen patients had good or very good results in the Merle d'Aubigne score after a median of 4.3 (range 2-5.6) years of follow-up. The surgical technique described enables the initial stable fixation of a standard prosthesis without additional osteosynthesis. Additional advantages include a shorter duration of surgery, a lower complication rate and a more rapid consolidation of the osteotomy.

Adolescent↗

PubMed2000

[Chondrocyte transplantation in PGLA/polydioxanone fleece].

The transplantation of chondrogenic cells in a supportive carrier structure proved to be a promising alternative for the treatment of cartilage defects. In the study presented we focused on the transplantation of allogeneic chondrocytes in a biodegradable polymer scaffold (PGLA/Polydioxanon) in articular cartilage defects in a rabbit defect model. Isolated allogeneic chondrocytes embedded in a PGLA polymer scaffold were transplanted into osteochondrogenic defects of the patellar groove and compared with empty defects and transplants of polymer scaffolds without cells. The histological and histochemical analysis was performed after 4 and 12 weeks. The transplant integration and the architecture of the newly formed cartilage were evaluated with a semiquantitative score. After 4 weeks the development of a hyaline-like cartilage tissue of the cell-polymer-transplants was observed, after 12 weeks the defects were nearly completely filled with hyaline-like cartilage. The biodegradation of the polymer construct did not affect the histological structure of the transplant area. Defects of the groups with empty defect and polymer transplants without cells revealed no or insufficient healing indices. The study demonstrated that biodegradable polymers served as suitable carriers for the chondrocyte transplantation, which is due to the in-vitro establishment of a semi-solid cartilage transplant and the resulting effective transplant fixation into the defect. In-vivo the polymer cell transplants seem to provide a supportive microenvironment for the development of hyaline cartilage. The controlled release of morphogenic factors or bioactive molecules and the use of pluripotent mesenchymal progenitor cells opens new perspectives for the optimization of cartilage repair procedures.

Animals↗

PubMed2000

The effect of anatomical positional relationships on kinetic parameters after total hip replacement.

The purpose of this study was to evaluate the significance of positional relationships of the components on gait after total hip replacement (THR). Gait was analysed using multicomponent force platforms integrated into a treadmill, in conjunction with an optoelectric measuring system. 26 patients, after undergoing total hip replacement, were classified according to the vertical and horizontal positions of the centre of rotation, the vertical position of the femur and the functional leg length, and compared with a control group. Deterioration in parameters of gait was observed following cranialisation of the centre of rotation or of the femur, whereas neither medial movement of the centre of rotation nor leg lengthening by up to 1 cm had any effect. This study emphasises the importance of considering, at the time of preoperative planning, the effect of the position of the prosthesis on the functional parameters of gait.

Adult↗

PubMed2000

The influence of obesity on perioperative morbidity and mortality in revision total hip arthroplasty.

The significance of obesity as a risk factor for postoperative complications was determined in a consecutive series of 229 cases of revision total hip replacement. The body mass index (BMI) was used as an objective measure to classify the patients. The group-wise analysis of data included all medical and procedure-related complications, the number of fatal cases, operative time, requirement for analgesics, the number of transfusions and perioperative haemoglobin levels. The results of our study demonstrate a clear association between obesity and operative time, whereas no statistically significant relationships were observed between obesity and the other parameters. We conclude that obesity does not have any significant influence on perioperative morbidity and mortality but is clearly related to operation time and, therefore, to higher costs per operation.

Adult↗

PubMed2000

Segmental bone repair by tissue-engineered periosteal cell transplants with bioresorbable fleece and fibrin scaffolds in rabbits.

The biological bone healing depends on the presence of osteochondral progenitors and their ability for proliferation. Isolated periosteal cells were seeded into biodegradable PGLA polymer fleece or fibrin beads and cultivated for 14 days after prior monolayer culture. On 12 New Zealand white rabbits 8 mm metadiaphyseal ulna defects were created bilaterally and subsequently filled with cell-fibrin beads, with polymers seeded with cells compared to controls with fibrin beads and polymers alone and untreated defects. A semiquantitative grading score was applied for histomorphological and radiological analysis after 28 days. Histologically intense bone formation was observed in both experimental groups with cell transplants only. The histological and radiological scoring was superior for both experimental groups. Control groups revealed only poor healing indices and untreated defects did not heal. The highest histological score was noted in the group with polymer fleeces containing periosteal cells. Applying the radiographic score system we determined a significant difference between experimental groups and controls without cells. The radiographic and histological scores for both experimental groups containing periosteal cells differed not significantly. The results strongly encourage the approach of the transplantation of pluripotent mesenchymal cells within a suitable carrier structure for the reconstruction of critical size bone defects.

Animals↗

PubMed2000

Cultivation of porcine cells from the nucleus pulposus in a fibrin/hyaluronic acid matrix.

Use of multiplied viable cells from the nucleus pulposus in altered discs, following in vitro cultivation, may be a promising therapy for degenerative disc disease. Up till now, alginate has been used as a three-dimensional cell carrier to cultivate nucleus pulposus cells. However, the biocompatibility of the alginate, which depends on the composition and purity of alginate materials used, has not been considered for in vivo application so far. In this study, we cultured porcine cells from the nucleus pulposus in a mixture of fibrin and hyaluronic acid (HA). The DNA content and proteoglycan synthesis were compared to those measured in an alginate matrix. Although the increase in DNA content was 2.5-fold higher in the alginate culture after 3 weeks, the proteoglycan synthesis in relation to the DNA content was significantly higher in the fibrin/HA matrix. We found that the fibrin/hyaluronic acid matrix can be used as a substrate for in vitro cultivation.

Animals↗

PubMed2000

Localized pigmented villonodular synovitis of the knee joint: neoplasm or reactive granuloma? A review of 18 cases.

OBJECTIVE: The localized form of pigmented villonodular synovitis of the knee joint is a rare disease with limited alteration of the synovial membrane, the pathogenesis of which is the subject of controversial discussion. METHODS: Eighteen cases have been documented in our hospital since 1976. All of the patients had additional cartilage or meniscus damage. Treatment consisted of excision of the lesion and the adjacent synovial membrane, as well as therapy of the additional damage. RESULTS: The patients who had received such therapy were followed for 3-9 yr, without any clinical, sonographic or magnetic resonance tomographic signs of recurrence. In addition to the lack of a tendency towards recurrence, none of the cases displayed any further characteristics of the diffuse form of villonodular synovitis, such as invasiveness or malignant transformation. CONCLUSIONS: We therefore suggest that pigmented villonodular synovitis of the knee joint should be classified more strictly than before into a potentially neoplastic (diffuse) form and a reactive granulomatous (local) form. From the cases observed, we conclude that degenerative joint lesions may be the cause of the reactive granulomatous form.

Adolescent↗

PubMed2000

Influencing factors on perioperative morbidity in knee arthroplasty.

In an unselected, prospective case control study, the incidence of risk factors and perioperative complications was investigated in 237 knees (203 patients) undergoing implantation of cementless total knee endoprostheses. Intraoperative complications and postoperative complications occurred in 84 patients (99 knees), with 61 specific orthopaedic complications in 50 patients (57 knees) and 74 nonsurgical complications in 55 patients (65 knees). The presence of cardiac, neurologic, or psychiatric concomitant diseases, advanced age, male gender, high-risk anesthesia scores, number and extent of intraoperative blood pressure fluctuations, and surgery under intubation anesthesia are associated significantly with the incidence of nonsurgical perioperative complications. In contrast, body weight, concomitant metabolic and circulatory diseases, previous surgery on the joint, origin of the articular disease, and the duration of surgery and tourniquet time do not correlate with the probability of a nonsurgical perioperative complication. A significant correlation with the parameters investigated could not be found for the occurrence of specific orthopaedic complications. The current report identifies specific risk factors that define patients with risk of having perioperative complications according to objective criteria. These parameters must be given individual consideration when establishing the indication and planning of surgery.

Adult↗

PubMed2000

Tissue engineered cartilage repair using cryopreserved and noncryopreserved chondrocytes.

The objective of this study was to reconstruct full thickness cartilage defects in rabbit knees with in vitro engineered cartilage tissue based on noncryopreserved and cryopreserved chondrocytes in polymer fleece scaffolds. Osteochondral defects in rabbits were filled with polymer cylinders with noncryopreserved or cryopreserved allogeneic chondrocytes and compared with empty defects and defects filled with polymers alone. The defects were evaluated macroscopically and histologically 4 and 12 weeks after surgery. Transplant samples were graded using a semiquantitative score system. Successful healing was defined as complete integration of a hyalinelike and structurally intact cartilage into the defect and occurred in 71% of the group with noncryopreserved chondrocytes after 4 weeks and 100% of the rabbit knees after 12 weeks, whereas hyalinelike cartilage was seen in 71% of the group with cryopreserved chondrocytes after 4 weeks, and in 85% after 12 weeks. No newly formed cancellous bone was present in the subchondral bone. In the control groups, no cartilagelike tissue was seen. Transplantation of chondrocytes in polymer fleece constructs is a suitable approach for joint cartilage repair. Noncryopreserved chondrocytes are preferred to cryopreserved chondrocytes because of their regenerative potential. In vitro engineered cartilage offers broad opportunities for optimization of cartilage transplantation based on the controlled use of morphogenic and biologically active factors such as transforming growth factor-beta and bone morphogenetic proteins.

Animals↗

PubMed1999

Retention of hyaluronic acid in alginate beads: aspects for in vitro cartilage engineering.

Alginate has been used successfully for three-dimensional chondrocyte cultures and may be important for cartilage transplant formation. However, alginate is not a natural component of the cartilage matrix. The aim of this study was (a) to supplement alginate with the extracellular matrix component hyaluronic acid; and (b) to analyze the hyaluronic acid retention in different alginate gels. Hyaluronan is assumed to improve proteoglycan retention and may be important for in vitro matrix formation, tissue turgor, and biomechanical quality. Alginate and hyaluronan were mixed with chondrocytes and polymerized as were alginate, hyaluronan, and fibrinogen. [3H]hyaluronan was used to quantitate the leakage of hyaluronan from the gel beads. After 28 days in culture, 1.2% alginate beads supplemented with 0.26% hyaluronan contained only 9% of the initial amount of hyaluronan whereas 2.4% alginate beads still contained about 55% of the initial 0.22% hyaluronan. Release of hyaluronan from the beads was significantly lower if the beads additionally contained fibrin. Alginate beads supplemented with hyaluronan or fibrin showed increased chondrocyte proliferation compared to controls. Supplemented hyaluronan greatly diffuses out of alginate gels of lower densities. It must be assumed also that most of the hyaluronan newly synthesized by chondrocytes in these cells diffuses into the surrounding culture medium. The in vitro development of a sufficiently hygroscopic cartilage ground substance therefore may be very limited. Sufficient hyaluronic acid retention can be achieved in alginate gels with concentrations above 1.2% or by addition of fibrin.

Alginates↗

PubMed1999

Joint cartilage regeneration by tissue engineering.

The research field of tissue engineering combines cells biology, biomaterial science, and surgery. Major long-term goals are tissue and organ replacement therapies using the patients' own cells. Our work is focused on the treatment of severe joint defects and on plastic surgery using in vitro engineered cartilage tissues. The practical approaches in cartilage engineering face problems with three-dimensional cell distribution or cell immobilization raising biocompatibility problems. The tissue engineering of cartilage is based on combining biocompatible cell embedding substances such as fibrin, agarose, alginate, hyaluronic acid and fiber fleece scaffolds of poly alpha-hydroxy acids (PLLA/PGLA). Different technical approaches were established: a) three-dimensional in vitro cultures of chondrocytes for the development of vital tissue transplants and b) interacting three-dimensional cultures consisting of different cell populations, such as BMP-transfected mesenchymal cells. The preshaped artificial tissue constructs were cultured in perfusion chambers to maintain a stable diffusion of nutrients during the in vitro pre-formation step. Subsequently, pre-formed tissues were implanted into nude mice and into 4 mm articular joint defects of rabbits. Transplants were found to produce cartilage typic morphological patterns and matrix. 80% of the transplants remained stable in vivo. However, 20% of the tissues are resorbed or replaced by a fibrous tissue. These results demonstrate that current artificial cartilage transplants are already feasible for plastic reconstruction. The treatment of severe joint defects, however, faces additional problems which are addressed in ongoing studies: (a) the fixation of engineered cartilage in joints, (b) the protection against chronic inflammatory degradation, and (c) the required enormous mechanical stability.

Animals↗