PURPOSE OF THE STUDYMany congenital and acquired disorders as well as sequelae of injury are associated with articular cartilage degeneration, which adversely affects the patient's quality of life. The currently used cell therapy with cultured chondrocytes has its disadvantages due to a process of de-differentiation of chondrocytes during cultivation. We believe that the mesenchymal stem cell therapy offers a new treatment options. MATERIAL AND METHODSThe adult mesenchymal stem cells (MSCs) for chondrocyte differentiation are usually obtained from bone marrow mesenchymal stem cells (BMSCs). In this study these cells were compared with mesenchymal stem cells derived from adipose tissue (AMSCs). The aim of the study was to verify the ability of human BMSCs and AMSCs to differentiate into chondrocytes in vitro in the presence or absence of transforming growth factor beta (TGF-β1). Human BMSCs and AMSCs were collected from healthy donors during orthopaedic surgeries, in vitro cultured in three passages to obtain the required quantity of cells. A pellet culture system was used for chondrocyte differentiation. RESULTSAt 21 days of cultivation, cell aggregates grown in the chondrogenic medium were larger than those cultured in the control medium. Both the BMSCs and AMSCs pellet cultures showed spontaneous chondrogenesis. Histological staining with haematoxylin and eosin and Masson's trichrome stains, as well as immunohistochemical staining to detect type II collagen revealed no apparent differences between the pellet cultures with TGF-β1 presence and those without it. The real-time RT-PCR detected expression of the type II collagen gene in all tested cultures. In the BMSCs pellet culture only, TGF-β1 presence resulted in a decrease in type I collagen mRNA levels and in an increase in type II collagen mRNA values. DISCUSSIONOur results showed an in vitro chondrogenic potential of mature human mesenchymal stem cells derived from both bone marrow and adipose tissue. In agreement with the relevant literature data, we suggest that both cell types have an equal prospect for use in cartilage tissue engineering.

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PURPOSE OF THE STUDYAvulsion fractures of the intercondylar eminence (ICE) of the tibia have become increasingly frequent in older school age. Due to recent advances in arthroscopic techniques, it is now possible to treat them by minimally invasive methods. This retrospective study presents evaluation of clinical outcomes of an arthroscopic technique using crossed K-wires. MATERIALThirty-five patients with ICE avulsion fracture, 17 girls and 18 boys at an average age of 13 years (7-18), were included in this study. All were indicated for surgical treatment on the basis of radiographic evidence of McKeever type II and III fractures. METHODSThe technique of arthroscopic reduction and fixation with crossed K-wires was used. The clinical evaluation of knee stability (anterior drawer test and Lachmann s-test) was made by one clinician. The modified Tegner-Lysholm score was assessed. RESULTSOf the 35 patients, 26 (74%) had minimal knee instability (anterior drawer up to 5 mm), two patients were primarily converted to open reduction with good results, and three (8.5%) experienced temporary knee instability (anterior drawer of 5-10 mm) that resolved spontaneously within 24 months of surgery. Four patients (11.5%) had symptoms of persistent residual instability (anterior drawer more than 10 mm) and were indicated for anterior cruciate ligament reconstruction at a later stage. The average Tegner-Lysholm scores were 86.3/100 and 98.6/100 at 6 and 24 months, respectively. DISCUSSIONAt the present time at our department, McKeever type II and III avulsion fractures of the intercondylar eminence are indicated for minimally invasive surgical treatment. By exact reduction it is possible to decrease the risk of post-operative knee instability. The current trend is the use of arthroscopy-assisted minimally invasive techniques such as the method of K-wire fixation described here. CONCLUSIONSArthroscopic surgery for ICE avulsion fractures shows good results, is associated with low post-operative risks, is minimally invasive and easy to reproduce. It can be recommended as the method of choice for treating ICE avulsion injury in children.

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