Biomedical subjects

M Janecek

Publications and source records attributed to M Janecek.

At least 19 recordsLinked to original sources

PubMed2006

[Minimally invasive and navigated implantation for total knee arthroplasty: X-ray analysis and early clinical results].

Total knee arthroplasty (TKA) alignment is one of the most important factors in long-term prosthesis survival. Minimally invasive surgical (MIS) procedures are becoming more common. There may be an increased overall complication rate, especially component malpositioning, due to poor visualisation. The disadvantage of restricted visualisation in the less invasive technique can be compensated by a navigation system. This combined procedure is described in this paper. A total of 40 Search Evolution TKAs were implanted using OrthoPilot navigation in the standard manner, and 40 TKAs were implanted using MIS via a subvastus approach. Primary osteoarthritis of the third or fourth degree, without severe valgus deformity, was the indication. These patients were then selected at random as they came to the institution. The results were evaluated radiologically and clinically.Pain, range of motion, gait and function, and the entire clinical score 10 days after the operation were significantly better in the MIS-group. At 6 and 12 weeks postoperatively, these results were no longer statistically significant. Ideal radiological results were obtained in all cases. No differences in limb axis and component alignment were found after the operation between the navigated groups. MIS is technically very demanding. That is why it should be used only in carefully selected cases. Its advantages occur in the first weeks after the surgery. The long-term results must still be determined.

Aged↗

PubMed2005

[Correlation of long-term clinical and radiological results after meniscectomies].

PURPOSE OF THE STUDY: Although surgical treatment of meniscus injuries has made great progress, meniscectomy remains the most frequently indicated intervention. The aim of this retrospective study was to evaluate the long-term radiological results of isolated subtotal and total meniscectomies and compare them with the clinical results. MATERIAL: The assessed group included 22 men and 8 women at an average age of 35 years; nine and 21 knees, respectively, were treated by isolated subtotal and total meniscectomy in the period from 1987 to 1989. The lateral meniscus was operated on in six knees and the medial meniscus in 24 knees. Patients with other injuries to the knee joint or with a systemic disease were not evaluated. The average follow-up was 16 years. The results were compared with the other, non-treated knee. METHODS: The results were assessed by means of the Lysholm scoring system which takes into account limping, support requirement, walking distances, instability, edema, stair ascent and descent, ability to squat and pain. Radiographic osteoarthritis of the knee was classified by the Kellgren and Lawrence system. A grade greater or equal to 2 was taken for a clear sign of arthritis. In addition, the anatomical axis of the lower extremity was evaluated. Anteroposterior projection of both knees under load was made in a standing position on long films and lateral projection was obtained separately on short films. RESULTS: The average Lysholm scores were 87 points (range, 41-100) and 91 points (range, 67-100) in the treated and non-treated knees, respectively. The outcome of meniscectomy was excellent in 14 (47 %), good in eight (27 %), satisfactory in five (16 %) and poor in three (10 %) knees. In 12 patients (40 %) the state of the treated knee was evaluated as being equal to that of the non-treated knee and in eight patients (27 %) it was even better. Osteoarthritis of the affected compartment was found in eight treated knees and that of the corresponding compartment on the opposite side in four knees. Grade 2 Kellgren- Lawrence radiographic changes were present in four, grade 3 in two and grade 4 in two knees treated by meniscectomy. The anatomic femoro-tibial angle differed between the treated and non-treated side, by 4 degrees on average (range, 2 degrees to 10 degrees ), in 13 (43 %) patients. DISCUSSION: Johnson et al. found at follow-up for about 17 years that osteoarthritis developed more often in the treated than in healthy contralateral knees (40 % as against 6 %). Tapper and Hoover reported that 45 % of men and 10 % of women were without subjective complaints at 10 to 30 years of follow up. In the relevant Czech literature, only Pasa et al. have recently paid attention to the development of lesions in knees treated by meniscectomy, but they have largely evaluated changes occurring after partial arthroscopic meniscectomies. CONCLUSIONS: The present study showed that osteoarthritis after subtotal or total meniscectomy developed in 27 % of the patients at an average follow-up of 16 years. In less than half of the patients, a deviation of the anatomical axis occurred in the treated lower extremity, as compared with the other healthy side. Lysholm scores worse in the treated than the non-treated knee were found in one third of the patients.However, a deviated knee joint axis and/or osteoarthritic lesions did not always correlate with deteriorated clinical findings.

Adolescent↗

PubMed2004

[A rare shortening of the first metatarsus of the foot and its treatment with distraction arthrodesis].

Multiple toes may develop on the medial or lateral side of the forefoot or in its middle. This may involve duplication of only the distal phalanx or the whole hallux including the metatarsal. In a duplicated big toe, the phalanx to be maintained, because short muscles of the leg are attached to it, is usually localized medially. A rare case of dysplasia of the first metatarsus, following a resection indicated in childhood for a hallux triples, is described in a 20-year-old girl. In order to remove hallux insufficiency and an overloading of the middle metatarsals, the authors decided to carry out a one-stage prolongation of the first metatarsal, using an autologous tricorticcal graft collected from the pelvis and a dynamic compression plate. No surgical treatment of the middle metatarsals was indicated because a disproportionate, short foot would result. Both the subjective and objective status of the patient at 6 months after the operation showed that the non-standard prolongation procedure was correctly indicated and allowed for physiological loading of the foot and restoration of normal walking.

Adult↗

PubMed2004

[Implantation of a non-cemented acetabulum with the use of a navigation system].

PURPOSE OF THE STUDY: To compare, on the basis of clinical and radiographic findings, the results of non-cemented acetabulum implantation involving the use of a CT-free navigation system with those of implantation without its use. MATERIAL: A total of 50 patients undergoing implantation of a non-cemented acetabulum in the period from April 2002 to September 2003 were evaluated. Twenty-five patients operated on without the navigation system were included in group 1 on a random basis and 25 patients treated with the use of the system constituted group 2. METHODS: Both groups were evaluated on the basis of clinical and X-ray findings. The radiographic measurement of acetabulular inclination was based on anteroposterior projection of both hips made on films on films equal in size. Anteversion of the acetabulum was assessed according to the Ackland system. The Merle d'Aubigne and Postel scores were used for clinical evaluation. The results were compared statistically. RESULTS: In group 1, the average inclination was 50.6 degrees (range, 38-62) and the average anteversion was 9.4 degrees (range, 3-18). In group 2, the values were 43.0 degrees (32-55) and 10.4 degrees (8-16) for the average inclination and anteversion, respectively. The difference in acetabular inclination between the two groups was statistically significant. When accuracy was evaluated, the difference in acetabular anteversion was statistically significant. DISCUSSION: The achievement of an optimal position of the acetabular component is one of the important factors for good, long-term outcomes of hip replacement. The optimal position that, as suggested by many authors, involves an inclination of 45 +/- 10 degrees and an anteversion of 15 +/- 10 degrees provides sufficient stability, low wear and a satisfactory range of motion in the hip joint. The results close to these values were achieved in the patients included in group 2. CONCLUSIONS: A comparison of the groups showed that the computer-assisted navigation system used in implantation resulted in an optimal position of the acetabular component.

Acetabulum↗

PubMed2003

Total knee arthroplasty implanted with and without kinematic navigation.

Between September 2000 and February 2002 we inserted 120 total knee arthroplasties. In 60 patients we used the standard technique, and in 60 patients we used the OrthoPilot navigation system. Postoperatively all patients had standing long radiographs of the lower extremity from the hip joint to the ankle. We considered the ideal value of the anatomic lateral tibiofemoral angle (LTFA) to be 174 degrees. In the standard group the mean value of LTFA was 174.9 degrees and in the navigation group 174.3 degrees. A deviation between 0 degrees and 2 degrees from the ideal value was seen in 42 cases in the standard group and in 53 cases in the navigation group. In the standard group 18 cases had a deviation of more than 2.1 degrees, whereas there were only seven cases in the navigation group with a deviation exceeding 2.1 degrees. There were no complications related to the use of the navigation system. The system affords a possibility to place femoral and tibial components precisely with less axis deviation than with the conventional technique.

Aged↗

PubMed2003

[Case report of extensive metallosis in extra-articular tissues after unicompartmental knee joint replacement].

The authors present a case of extensive metallosis of the knee joint resulting from the secondary abrasive wear of components of a unicompartmental alloplasty. Eight years after medial condyle replacement, an eighty-year-old patient presented with a break of the femoral component. This resulted in a rapid wear of tibial polyethylene and the development of secondary friction between two metal surfaces. The generation of a large number of metal particles produced an increase in the actual metal surface. This extensive articular metallosis affected not only intra-articular but also extraarticular tissues and the subchondral bone. Histological examination confirmed the presence of a large amount of opaque pigment in histiocytes. The condition was treated by total knee arthroplasty with resection of the posterior cruciate ligament (stabilizing plateau). The authors discuss the causes of metallosis development and its various types; they draw attention to the scarcity of literature data on this condition. Metallosis is a combined chemical and toxic reaction which, if the contact surface of a metal implant is large, may cause extensive damage to the surrounding tissue, the bone included.

Aged↗

PubMed2003

[Indications for arthrodesis of the knee joint in modern orthopedics].

INTRODUCTION: Indication for arthrodesis of the knee joint is nowadays most frequently failure of a total endoprosthesis, usually septic. A less frequent indication is purulent gonitis, frequently after corticoid administration, the condition after a complicated intraarticular fracture with subsequent arthritis or oncological disease of the bones in the area of the knee joint. MATERIAL AND METHODS: In the course of 2000 to 2002 at the authors' department 15 arthrodeses were implanted. In three cases the indication for arthrodesis was purulent gonitis, in three cases the condition after an open articular injury associated with infectious complications and in the remaining nine cases failure of an endoprosthesis of the knee, incl. seven caused by infection. The patients were three men and 12 women, mean age 64 years (30-75 years). For stabilization of the arthrodesis 9x external fixation was used, 5x plates and 1x intramedullary osteosynthesis. RESULTS: In all cases consolidation of the arthrodesis was achieved. In one case the external fixation had to be replaced by a system of two fixation devices and in one case correction of the axial position of the extremity was made. The presence of external fixation was perceived negatively in particular by female patients. DISCUSSION: Plate osteosynthesis and the use of external fixation devices are relatively quick, cheap and considerate methods of arthrodesis. External fixation must be used in acute virulent infections while plate osteosynthesis can be indicated in its absence. The characteristic of intramedullary fixation is similar, however special nails used for arthrodesis of the knee are several times more expensive than the previous types of stabilization. The advantage is the possibility to use a massive bone graft to fill the defect.

Adult↗

PubMed2001

Is plastic flow always controlled by dislocation mobility? An answer from in situ transmission electron microscopy straining tests.

In situ transmission electron microscopy (TEM) straining experiments are used to illustrate in two extreme cases the possible role of dislocation nucleation and exhaustion as a controlling factor in plastic flow. In the first example (FeAl intermetallic compounds), a thermally activated dislocation exhaustion is responsible for an anomalous stress-temperature dependence and an associated small strain rate sensitivity, the latter being evidenced during in situ experiments through unstable localized slip. The second example (heavily drawn pearlite) shows specific dislocation loop nucleation processes that may account for the Hall-Petch law breakdown characteristic of fine scale nanostructures.

Journal Article↗

PubMed1999

Intraoperative probes and imaging probes.

Intraoperative probes have been employed to assist in the detection and removal of tumors for more than 50 years. For a period of about 40 years, essentially every detector type that could be miniaturized had been tested or at least suggested for use as an intraoperative probe. These detectors included basic Geiger-Müller (GM) tubes, scintillation detectors, and even state-of-the-art solid state detectors. The radiopharmaceuticals have progressed from (32)PO(4)(-) injections for brain tumors to sophisticated monoclonal antibodies labeled with iodine-125 for colorectal cancers. The early work was mostly anecdotal, primarily interdisciplinary collaborations between surgeons and physical scientists. These collaborations produced a few publications, but never seemed to result in an ongoing clinical practice. In the mid 1980s, several companies offered basic gamma-detecting intraoperative probes as products. This led to the rapid development of radioimmunoguided surgery (RIGS) and sentinel node detection as regularly practiced procedures to assist in the diagnosis and treatment of cancer. In recent years intraoperative imaging probes have been developed. These devices add the ability to see the details of the detected activity, giving the potential of using the technique in a low-contrast environment. Intraoperative probes are now established as clinical devices, they have a commercial infrastructure to support their continued use, and there is ongoing research, both commercial and academic, that would seem to ensure continued progress and renewed interest in this slowly developing field.

Female↗

PubMed1993

Determination of erythromycin A by liquid chromatography and electrochemical detection, with application to salmon tissue.

The chromatographic performance of erythromycin A (EA) is improved significantly over that achieved on polymeric columns by using a sterically shielded octyldiisopropylsilica (Zorbax Rx-C8) column and a neutral mobile phase consisting of 5 mM aqueous sodium perchlorate-acetonitrile (50:50). This mobile phase facilitates electrochemical detection of EA at the 3-pmol level. Temperature control of both column and detection cell is important for minimizing detector noise and drift. A clean-up procedure, based on aminopropylsilica solid-phase extraction, allows the detection of EA in salmon flesh down to the 0.2-ppm level. Some of the metabolites of EA that retain the tertiary amine may also be detected by this method.

Animals↗

PubMed1993

Analysis of paralytic shellfish poisoning toxins by automated pre-column oxidation and microcolumn liquid chromatography with fluorescence detection.

Periodate oxidation of the toxins responsible for paralytic shellfish poisoning (PSP) yields fluorescent purines suitable for trace analysis by reversed-phase LC. Mobile phases containing perfluorinated acids, such as heptafluorobutyric acid, as ion-pair agents were found to provide high capacity factors for the oxidized products. Gradient elution on a microbore column with large volume injections and fluorescence detection permitted the detection of femtomole quantities of PSP toxins. A fully automated pre-column oxidation procedure was developed for an LC autosampler system in order to improve precision and allow unattended analyses. The complete method was applied successfully to various samples, including shellfish and toxic phytoplankton.

Autoanalysis↗

PubMed1993

Characterization of the oxidation products of paralytic shellfish poisoning toxins by liquid chromatography/mass spectrometry.

Periodate oxidation of the toxins responsible for paralytic shellfish poisoning (PSP) yields fluorescent products that are useful for trace analysis by reversed-phase liquid chromatography. Some toxins are oxidized to the same product, while others are transformed to a mixture of products; in all cases, the products are too unstable to be isolated preparatively. A mobile phase containing heptafluorobutyric acid as an ion-pair agent was developed to improve compatibility with liquid chromatography/mass spectrometry (LC/MS) analysis. Several LC/MS techniques were investigated: chemical ionization with the moving belt interface, atmospheric-pressure chemical ionization, thermospray, continuous-flow fast-atom bombardment, and ion-spray. Only LC/ion-spray MS was able to provide spectra of the oxidized products. The products were characterized as purines resulting from: (a) breakage of the C4-C12 bond and aromatization of the remaining rings (loss of 4 hydrogens); (b) partial elimination of a carbamoyl or N-sulfocarbamoyl side-chain (this is promoted by the presence of an N-1-hydroxy group); and (c) partial hydrolysis of an N-sulfocarbamoyl side-chain to a carbamoyl group.

Gas Chromatography-Mass Spectrometry↗

PubMed1989

[A bone cement containing methotrexate in an experiment and in clinical practice].

The authors submit their initial experience with the use of bone cement with methotrexate in the treatment of primary and secondary malignities of bones. As a basis they use the analogy of using bone cement with gentamycin the molecular structure of which is similar to that of methtrexate. In the experimental part of the work in vitro evidence was provided of methotrexate stability when exposed to heat or oxidation; and the kinetics of its release from pores of bone cement were revealed. In experimental dogs the effect of cement with methotrexate on neighbouring bone was investigated in the early period in the immediate vicinity necrosis of the trabeculae was found, during the late period healing processes. The clinical use of bone cement with methotrexate was started in 1986. In 17 surviving patients only in one case local progression of a tumour in the vicinity of cement with methotrexate was found. The aim of the work is to find a possible local treatment of bone malignities, in particular metastatic ones, which will be not only an emergency solution but will extend our therapeutic possibilities.

Animals↗

PubMed1988