Karel Urban

In vivo behaviour of low-temperature calcium-deficient hydroxyapatite: comparison with deproteinised bovine bone

This study aims to evaluate in detail the biological osteoconductive properties of the low-temperature synthetic porous calcium-deficient hydroxyapatite and to compare it with the biological apatite. Bone reactions to granules of similar sizes of the low-temperature hydroxyapatite and commercially available non-sintered deproteinized bovine bone were compared. Two different temperatures were used to fabricate two batches of newly developed porous hydroxyapatite with different carbonate groups content and specific surface area. The histological analysis of specimens with histomorphometry was performed at different time after in vivo implantation. Based on histological analysis, the level of bone formation in the spaces between the implanted granules and through the interconnected pores of all implanted materials within a cortical region (bone area ingrowth 72–85 %) was several-fold higher than within a cancellous bone site (bone area ingrowth 16–28 %) at three and six months after implantation. Within the cancellous bone site, bone coverage of the implanted material at six months was significantly higher in hydroxyapatite material fabricated using low-temperature synthesis and subsequent processing at 150°C than in hydroxyapatite scaffold developed using low-temperature synthesis with subsequent processing at 700°C or deproteinized bovine bone. According to our study, the bioactive properties of the low-temperature calcium-deficient hydroxyapatite are comparable with the biological apatite. The favourable influence of a high specific surface area of a low-temperature calcium-deficient hydroxyapatite on in vivo bone formation was emphasized.

Differentiated adamantinoma of the fibula: a rhabdoid variant.

A benign- appearing osteolytic lesion surrounded by a sclerotic rim was found in the upper fibula of a 25-year-old man. Based on histological features the definitive diagnosis of osteofibrous dysplasia–differentiated adamantinoma was made. The correct histological diagnosis of differentiated adamantinoma depends on factors such as the uniform predominance of an osteofibrous dysplasia-like pattern, and scattered epithelial elements positive for cytokeratin and vimentin. In this case the scattered epithelial cells had abundant eosinophilic cytoplasm and resembled rhabdoid elements, but immunohistochemistry proved their epithelial origin.

Behavior of bioactive glass-ceramic implanted into long bone defects: a scintigraphic study.

The purpose of the study was to assess the long-term behavior and incorporation of the bioactive oxyhydroxyapatite glass-ceramic used to fill defects of long bones after curettage of bone cysts in 17 patients. The method of evaluation was a three-phase bone scintigraphy combined with radiographic and clinical evaluation. At a mean follow-up of 7 years, the glass-ceramic material had been completely incorporated. Mean uptake ratio was 1.31±0.25 after implantation of glass-ceramic in the metaphyseal region and 2.07±0.62 after implantation of glass-ceramic in the diaphyseal region (P<0.05). Mean uptake ratio was 1.40±0.30 in patients without persistent pain and 2.07±0.69 in patients who complained of pain in the area of synthetic filling (P<0.05). The bioactive glass-ceramic can be implanted into the metaphyseal defects of long bones, but this material is not suitable for filling the diaphyseal defects.

Methotrexate released in vitro from bone cement inhibits human stem cell proliferation in S/G2 phase

Methotrexate (MTX) released from bone cement showed a useful local effect in animal models of bone tumours. However, local toxic reactions such as impaired wound healing were observed in areas surrounding the MTX-loaded implant. Therefore, we hypothesised that MTX released from bone cement would have harmful effects on human mesenchymal stem cells (MSC)—one of the basic components of bone marrow and tissue reparatory processes. Moreover, elution of MTX was calculated from implants prepared either with liquid or powdered MTX. During the 28-day incubation, the cement compounded with liquid MTX showed the highest elution rate of the drug. MTX released from pellets produced a significant decrease in proliferation of MSC as a consequence of a blockade of their cell cycle in the S/G2 phase. These findings indicate impairment of stem cell function in marginal areas surrounding the MTX-loaded cement and may help to explain problems with regeneration of tissues in these locations.RésuméLe Methotrexate (MTX) libéré par le ciment acrylique a un effet certain sur les tumeurs osseuses développées sur un modèle animal. Cependant, des réactions toxiques locales telles que défauts de cicatrisation ont été observées à proximité de l’implantation de ce ciment. Nous faisons donc l’hypothèse que le Methotrexate MTX libéré par le ciment a un effet nocif néfaste sur les cellules mésenchyméteuses humaines MSC qui sont l’un des composants de base de la moelle osseuse et des phénomènes de la réparation tissulaire. De plus, la dynamique de pénétration du méthotrexate a été analysée à partir d’implants préparés avec du liquide ou de la poudre de méthotrexate. Au cours des 28 jours d’incubation, le ciment préparé avec du méthotrexate liquide montre un taux important de pénétration de la drogue. Le méthotrexate libéré des billes de ciment entraîne une diminution significative de la prolifération des cellules mésenchyméteuses avec un bloquage cellulaire à la phase S/G2. Ces travaux montrent que la fonction cellulaire est altérée au voisInage du méthotrexate pouvant expliquer les problèmes de régénétration tissulaire.

Utilizing Autologous Multipotent Mesenchymal Stromal Cells and β-Tricalcium Phosphate Scaffold in Human Bone Defects: A Prospective, Controlled Feasibility Trial

The purpose of this prospective controlled study was to compare healing quality following the implantation of ultraporous β-tricalcium phosphate, containing either expanded autologous mesenchymal stromal cells (trial group, 9 patients) or β-tricalcium phosphate alone (control group, 9 patients), into femoral defects during revision total hip arthroplasty. Both groups were assessed using the Harris Hip Score, radiography, and DEXA scanning at 6 weeks and 3, 6, and 12 months postoperatively. A significant difference in the bone defect healing was observed between both groups of patients (P < 0.05). In the trial group, trabecular remodeling was found in all nine patients and in the control group, in 1 patient only. Whereas, over the 12-month follow-up period, no significant difference was observed between both groups of patients in terms of the resorption of β-tricalcium phosphate, the significant differences were documented in the presence of radiolucency and bone trabeculation through the defect (P < 0.05). Using autologous mesenchymal stromal cells combined with a β-tricalcium phosphate scaffold is a feasible, safe, and effective approach for management of bone defects with compromised microenvironment. The clinical trial was registered at the EU Clinical Trials Register before patient recruitment has begun (EudraCT number 2012-005599-33).

Comparative Outcomes of Total Knee Arthroplasty on Physically Active and Passive Patients

The physical activity of the population is decreasing due to an increase in sedentary lifestyles. The aim of the study was to analyze midterm results of total knee arthroplasty according to the lifelong physical activity of the patients. We evaluated 37 patients (23 women, 14 men), with age average 70.0 years (range 53-87). We divided the patients according to lifelong physical activity. The active group included 11 patients with any history of physical activity and the passive included 26 patients with a sedentary lifestyle. No intergroup differences existed in age, gender or preoperative Knee Score. The active group had a higher postoperative Knee Score 90.5 (+/- 5.0) compared to the passive 87.4 (+/- 5.0). Pain after arthroplasty was experienced significantly more in the active group. Between the active 87.3 (+/- 9.3) and passive 67.5 (+/- 16.7) groups we measured a statistically significant difference in the improvement of Functional Score - ability to walk and climb stairs. Sedentary lifestyle affects the clinical outcomes of total knee arthroplasty. This data is demonstrating that physical activity ameliorate functional postoperative results.

Comparative Study on the Application of Mesenchymal Stromal Cells Combined with Tricalcium Phosphate Scaffold into Femoral Bone Defects

This prospective study sought to evaluate the healing quality of implanted ultraporous β-tricalcium phosphate sown with expanded autologous mesenchymal stromal cells (MSCs) into femoral defects during revision hip arthroplasty. A total of 37 osseous defects in 37 patients were treated and evaluated concerning bone regeneration. Nineteen subjects received β-tricalcium phosphate graft material serving as a carrier of expanded autologous MSCs (the trial group A), nine subjects received β-tricalcium phosphate graft material only (the study group B) and nine subjects received cancellous allografts only (the control group C). Clinical and radiographic evaluations were scheduled at 6 weeks, 3, 6, and 12 months post-operatively, and performed at the most recent visit as well. All observed complications were recorded during follow-up to assess the use of an ultraporous β-tricalcium phosphate synthetic graft material combined with expanded MSCs in bone defect repair. The resulting data from participants with accomplished follow-up were processed and statistically evaluated with a Freeman–Halton modification of the Fischer’s exact test, a P < 0.05 value was considered to be significant. Whereas no significant difference was observed between the trial group A with β-tricalcium phosphate synthetic graft material serving as a carrier of expanded autologous MSCs and control group C with cancellous impaction allografting in terms of the bone defect healing, significant differences were documented between the study group B with β-tricalcium phosphate graft material only and control group C. Regarding adverse effects, six serious events were recorded during the clinical trial with no causal relationship to the cell product. β-tricalcium phosphate synthetic graft material serving as a carrier of expanded autologous MSCs appears safe and promotes the healing of bone defects in a jeopardized and/or impaired microenvironment. This clinical trial was registered at the EU Clinical Trials Register before patient recruitment (Registration number: EudraCT number 2012-005599-33; Date of registration: 2013-02-04).

Grade-III slipped capital femoral epiphysis with unstability: a report of three cases.

We reviewed the cases of three patients with an unstable grade-III slipped capital femoral epiphysis treated between 2001 and 2003. Clinical records and imaging studies were reviewed for patients history, anatomic features of the slip, definitive treatment and clinical outcome. The duration of the follow-up ranged from twenty-four to fourty-eight months.