[Our Experience with ICON Hip Resurfacing System]. / Nase zkusenosti s povrchovou náhradou kycelního kloubu ICON.

PURPOSE OF THE STUDY Our study aimed to assess the mid-term outcomes and complications with the ICON hip resurfacing system and to carry out a detailed analysis of pitfalls and risks associated with pairing the bearing surfaces of metal-on-metal hip implants. MATERIAL AND METHODS A total of 52 hip joints were assessed in 43 patients who received the ICON hip resurfacing system at our department between 2009 and 2013. The cohort included 34 men and 9 women. Their age at the time of primary surgery ranged from 34 to 67 years, with the mean age of 51.8 years. The mean follow-up was 7.6 years. The evaluation focused on the position and osseointegration of both components, bone remodelling around the implant, and signs of potential aseptic loosening. The functional status of the hip was assessed by Harris Hip Score. RESULTS The primary stability of both components was always good, there were no femoral neck fractures reported in our cohort. All the acetabular components were stable, showing appropriate osseointegration, with no radiolucent zones or signs of osteolysis around them. There was not a single case of the femoral component stem being in a biomechanically disadvantageous varus position. In zone I and III according to Beaulé, cancellous bone osteolysis developed in two patients. The narrowing of the femoral neck below the end of the femoral component, compared to postoperative X-rays, achieved the mean value of 1.3% according to Grammatopolouse. The HHS increased from 64 to 95.5 points. An excellent outcome was observed in 48 joints, whereas the outcome of the remaining 4 joints was very good. The mean survival rate of the resurfacing hip implant calculated using the Kaplan-Meier analysis achieved 100%. The cobalt and chromium levels in the blood of patients did not exceed the reference physiological value. DISCUSSION The resurfacing system enables to preserve the bone tissue of the metaphysis and a part of the femoral head. The reduced mechanical endurance of the peripheral part of femoral components smaller in size caused by implant malposition resulted in fatal consequences in the ASR system. Greater range of motion conditioned by the design of the resurfacing system led to a mechanical wear, with a significant increase in the concentration of metal particles in the effective joint space. The elevated levels of cobalt and chromium ions in some patients induced delayed-type hypersensitivity with subsequent development of aseptic lymphocyte-dominated vasculitis associated lesions presented as peri-acetabular changes (pseudotumors to osteolysis) with subsequent failure of implant fixation. We have not observed this complication in the ICON system as yet. In patients suffering from hip pain after the resurfacing hip arthroplasty and simultaneous high chromium and cobalt blood levels, pelvic CT/MRI is indicated with reduction of artefacts around the metal material. Surgical treatment of soft tissue affections, bone defects and reimplantation using conventional or revisioncementless components is a possible treatment option. CONCLUSIONS The ideal patient indicated for hip resurfacing is a physically active man under 60 years of age (with a femoral head size of 54-60 mm), with primary or secondary osteoarthritis, no joint deformity, with a good quality bone tissue in the femoral neck and head region. As for the functional performance, the resurfacing system allows the patients a large range of motion with very good joint stability immediately after surgery. Despite that, the metal-on-metal tribological pairing must be approached with caution. The risk of developing lesions associated with ALVAL is unpredictable. In our cohort of patients with ICON hip resurfacing system, mostly excellent outcomes with minimum complications were reported provided the indication criteria and the correct surgical procedure had been complied with. Key words: hip resurfacing system, metal articulating surfaces, adverse reaction to metal particles, aseptic lymphocytedominated vasculitis associated lesions, pseudotumor.

[Mid-Term to Long-Term Results of Revision Total Hip Arthroplasty Using the Oval-Shaped Acetabular Cup - TC Type]. / Strednedobé az dlouhodobé výsledky reimplantací totální náhrady kycelního kloubu pri pouzití oválné revizní jamky ­ typ TC.

INTRODUCTION The purpose of our paper is to evaluate the mid-term to long-term results and to confirm the basic criteria of a high-quality revision implant: safe bridging of bone defects, achievement of reliable primary fixation of revision acetabular cup, achievement of good secondary stability with documentable osteointegration of cup and demonstration of remodelling of transplanted bone tissue in the area of defects and in spaces between the implant ribs. MATERIAL AND METHODS Altogether 36 patients (38 cups) were evaluated who had undergone revision hip arthroplasty in the period from 2004 to 2010. The mean follow-up was 8.2 years (5.1-11.6 years after the reimplantation, more than 10 years in 16 patients who underwent surgery). The position and osseointegration of the implant were assessed by digital radiography, the remodelling of transplanted bone tissues in the area of defects and between the implant ribs by computed tomography with reducing artefacts around the metal implant (Aquilion 64 - Toshiba Medical Systems), and for the clinical outcomes the Harris Hip Score was used. RESULTS Preoperatively, the condition of the hip joint based on the Harris Hip Score was in 30 cases evaluated as poor, in 8 patients as satisfactory. At the time of final evaluation, 8 patients achieved excellent results, in 19 patients the condition of the joint was very good (in 2 patients bilaterally), in 6 patients it was considered satisfactory and in 3 patients poor. The mean value for HHS increased from 39.5 to 84.5. Based on the radiography evaluation, in 27 patients (in 2 patients bilaterally) the osseointegration of the revision cup was good, in 8 cases with a radiolucent line of 2-4 mm in width in DeLee zone III, in one case proximal migration of the cup occurred caused by deep infection. The informed consent form for pelvic CT was signed by 25 patients of our cohort. Remodelling of bone tissue in the space between the ribs of the implant was always detected, the presence of bone cysts was not reported, the bone defects following the application of autologous spongioplasty in the monitored patients were healed. In 6 patients, an ingrowth of fibrous tissue of 2-4 mm in width in the convexity of the cup was detected. The mean survival of the revision oval-shaped cup - TC type with a follow-up of 8.2 years after the reimplantation based on Kaplan-Meier analysis was 91.4 %. DISCUSSION The number of revision total hip arthroplasties due to a younger age of patients who undergo alloplasty keeps growing. The choice of a revision implant should always match the intraoperative finding and the bone tissue quality. The standard uncemented implants with osteoactive surface can be opted for when anterior and posterior column of the acetabulum are intact (IIA and IIB according to Paprosky). Starting from type IIC, also the proximal part of acetabulum shall be considered. At our department, preference is given to the revision cup - TC type. The oval shape facilitates a lower degree of bone resection and easier restoration of the anatomical centre of rotation. Careful debridement of granulating and necrotic tissue, thorough treatment of bone defects and osteoactive surface of implants in case of adequate primary fixation of the cup substantially contribute to the quality of its osseointegration. Greater rigidity of fixation verified by pull-out tests enables to insert angular stable screws into the gaps in the proximal part of the cup. There is still room for improvement in treating the bone defect. The application of allogenic bone grafts into the defects and spaces between the ribs of the TC cup is more challenging than the use of augmentation in the systems with trabecular titanium. Based on the evaluation of CT scans, remodelling of the transplanted bone occurs, therefore the defect zone is reduced. CONCLUSIONS The oval-shaped uncemented cup - type TC meets the requirements placed on a state-of the art revision implant, moreover its specific construction helps improve the conditions where another re-operation of acetabulum is necessary. By evaluating mid-term to long-term results of non-homogenous group of 36 patients (38 cups) we have obtained data on joint function comparable to similar groups with revision uncemented implants presented in our and foreign literature. Key words: revision oval-shaped cup, bone remodelling, pull-out tests, angular stable screws, computed tomography.

Xenogeneic protein-free cultivation of mesenchymal stromal cells - towards clinical applications.

We have studied a rapid cultivation method for human mesenchymal stromal cells based on CellGroTM medium and human serum, supplemented with insulin, ascorbic acid, dexamethasone, epidermal growth factor, platelet-derived growth factor BB, macrophage colony-stimulating factor and fibroblast growth factor 2. This study has shown that rapid expansion of human multipotent mesenchymal stromal cells using human serum could not be achieved without addition of growth factors. Furthermore, we have found that insulin and, quite probably, epidermal growth factor may be omitted from our formula without loss of colony-forming capacity or total cell yield. On the other hand, dexamethasone, ascorbic acid and fibroblast growth factor 2 were necessary for the growth and colony-forming capacity of multipotent mesenchymal stromal cells, while platelet-derived growth factor BB prevented their differentiation into adipogenic lineage. Moreover, multipotent mesenchymal stromal cells cultivated in our system expressed higher levels of bone morphogenetic protein 2, but not bone morphogenetic protein 7, than cells cultivated in α-MEM with foetal bovine serum. This shows that our system promotes differentiation of mesenchymal cells towards osteogenic and chondrogenic lineages, making them more suitable for bone and cartilage engineering than cells grown in conventional media. Furthermore, we have proved that these cells may be conveniently cultivated in a closed system, in vessels certified for clinical use (RoboFlaskTM), making the transfer of our cultivation technology to good clinical practice easier and more convenient.

[Xenogeneic protein free cultivation of mesenchymal multipotent stromal cells]. / Kultivace mezenchymových kmenových bunek bez xenogenních bílkovin.

PURPOSE OF THE STUDY: The aim of this study was to compare the standard laboratory method of cultivation of mesenchymal multipotent stromal cells (MSC) and a novel technique of rapid MSC expansion focused on simple clinical use. MATERIAL AND METHODS: Bone marrow mononuclear cells of donors were cultured for 14 days by the standard and the new cultivation method. The standard method (STD) was based on an alpha MEM medium supplemented with foetal calf serum (FCS). The new animal protein-free method (CLI) was based on the clinical grade medium CellgroTM, pooled human serum and human recombinant growth factors (EGF, PDGF-BB, M-CSF, FGF-2) supplemented with dexamethasone, insulin and ascorbic acid. The cell product was analyzed by flow cytometry. Furthermore, the cell products of STD and CLI methods were differentiated in vitro, and histochemical and immunohistochemical analyses, electron microscopy and elemental analysis were performed. Some cells were seeded on biodegradable scaffolds, in vivo implanted into immunodeficient mice for 6 weeks and evaluated by histological methods. RESULTS: Yields of the CLI method after 14 days of cultivation were 40-fold higher than those obtained by the STD technique (p<0.05). Cell products of both STD and CLI methods fulfilled the criteria of MSC in terms of antigen expression assessed by flow cytometry, as well as osteogenic, chondrogenic and adipogenic in vitro differentiation assays. Moreover, these cells seeded on three-dimensional scaffolds cultured in osteogenic medium produced mineral deposits and a fibrillar extracellular matrix seen with the electron microscope. Deposits examined by element analysis contained calcium and phosphorus at a ratio of 5 to 3, which corresponded to hydroxyapatite. The cell product seeded on biodegradable scaffolds and implanted into immunodeficient mice was able to form a bone-like calcified tissue with blood supply of mouse origin. DISCUSSION: The currently used methods of cultivation have certain disadvantages compared to the CLI technique, such as a longer cultivation period, need of primary expansion and reseeding and use of FCS with all its potential risks. High yields of cells obtained by the CLI method in a very short time make the use of cultured cells potentially suitable for an acute trauma management. Other therapeutic non-orthotopic applications of CLI-cultured cells have to be further investigated. CONCLUSIONS: The CLI method is unique, rapid, simple and lacking the addition of animal proteins. CLI-cultured cells fulfil the criteria of MSC. The CLI method potentially allows for closed system cultivation in good manufacturing practice (GMP) conditions. It seems to be easily transferable to good clinical practice compared to other protocols and should extend the possibilities of cell therapy and tissue engineering of cartilage and bone. The new method is protected by Czech patent 301 148 and by Europian patent EP 1999250 according to Czech and international laws.