[Fractures of the lateral process of the talus-snowboarder's ankle]. / Frakturen des Processus lateralis tali ­ "snowboarder's ankle".

Fractures of the lateral tubercle of the talus (PLT) are rare. With the increasing popularity of the trend sport snowboarding, the incidence of PLT fractures has increased. The most common classification of PLT fractures is the Hawkins classification. The aim of this review was to raise awareness for the injury and discuss the current evidence. A literature search revealed eight studies, each including at least seven patients. Six out of the eight studies were descriptive, retrospective case series without predefined treatment concepts. These resulted in only moderate treatment outcomes. Due to the low number of patients, the lack of computed tomography (CT) or magnetic resonance imaging (MRI) and inconsistent treatment approaches, these studies do not allow to draw conclusions on a treatment concept for PLT fractures. The other two studies validated existing treatment regimens. Overall, surgical treatment of dislocated fractures and conservative treatment of non-dislocated fractures was carried out with satisfactory results. The outcome of conservative treatment of dislocated factures remains unclear. A reason for the inconsistent treatment results could be the observed concomitant injuries, including dislocation of the tendons of the peroneus muscles (46%), calcaneal chondral injuries (48%) and subluxation of the subtalar joint (7%). Based on the limited evidence available, the authors recommend the application of CT and MRI for PLT fractures to assess concomitant injuries, which are the primary indication for surgery. Dislocated type I and II fractures (>2 mm) should be treated operatively, type III and non-dislocated type I and II fractures can be treated conservatively by immobilization and partial weight-bearing for 6 weeks.

Percutaneous iliosacral screw insertion: malpositioning and revision rate of screws with regards to application technique (navigated vs. Conventional).

BACKGROUND: Conventional percutaneous iliosacral screw placement in pelvic surgery is considered to be a highly demanding operative technique with a high rate of screw malpositions, which may be associated with the risk of neurologic damage or inefficient stability. In the conventional technique, the correct entry point for the screw and the small target corridor for the iliosacral screw may be difficult to visualize using an image intensifier. We tried to find out in this study whether the positioning of percutaneous screw implantations could be optimized by evaluating the rate and grade of malpositions and whether the needed revisions could be reduced by using computer navigation and three-dimensional (3D) image intensifier. METHODS: A group of 54 patients with 63 screws implanted using computer navigation was compared with 87 patients with 131 screws implanted using the conventional fluoroscopic technique. The exact screw position was controlled in a postoperative computed tomography scan, and the grade of malposition of every screw was investigated and compared. RESULTS: A complete intraosseous screw position was found in 42% of cases using the conventional technique and was significantly less compared with 81% using a 3D image intensifier in combination with a navigation system. Moreover, the revision rate of 1.6% was significantly less in the navigated group compared with 19% in the conventional group. CONCLUSIONS: The results indicate that 3D-computer navigation of the percutaneous iliosacral screw insertion can facilitate surgical performance in respect to reducing screw malposition and revision rates.

[The reversed locked internal plate fixator as an alternative internal fixation of problematic proximal femur fractures]. / Der umgedrehte Plattenfixateur zur osteosynthetischen Stabilisierung bei erschwerter Frakturheilung am proximalen Femur.

AIM: The aim of the study was to evaluate the application of a locked internal fixator in complex fractures of the proximal femur, in which the internal fixation with standard implants was not possible due to poor quality of bone or already failed internal fixation in the past. METHOD: Ten patients suffering from a pertrochanteric (n = 5), periprosthetic (n = 1) or subtrochanteric (n = 4) femural fracture between 2003 and 2008 were prospectively registered, underwent open reduction and internal fixation with an "upside-down" femur LISS (less invasive stabilisation system) and were followed up. In all these patients a primary internal fixation had failed or the local bone situation and circulation were poor. The mean follow-up was 14 +/- 25 months. X-ray images and a clinical examination were performed at each appointment. RESULTS: All fractures reached a primarily stable fixation with the locked internal plate fixator. Seven patients showed a complete bone healing after 3 months of follow-up and could bear full body weight afterwards. Three patients with preoperatively existing vascular disease or chronic osteomyelitis showed a deep wound infection postoperatively, which led to the explantation of the implant. CONCLUSIONS: The "reversed" locked internal fixator could be a successful alternative implant for stabilisation of proximal femur fractures which could not be fixated by standard implants due to poor bone quality and circulation. It can also be used as a salvage procedure after internal failed fixation in proximal femur fractures.

Survival of human mesenchymal stromal cells from bone marrow and adipose tissue after xenogenic transplantation in immunocompetent mice.

INTRODUCTION: Mesenchymal stromal cells (MSC) represent an attractive cell population for tissue engineering purposes. As MSC are described as immunoprivileged, non-autologous applications seem possible. A basic requirement is the survival of MSC after transplantation in the host. The purpose of the current paper was to evaluate the survival of undifferentiated and osteogenically induced human MSC from different origins after transplantation in immunocompetent mice. METHODS: Human MSC were isolated from bone marrow (BMSC) and adipose tissue (ASC). After cultivation on mineralized collagen, MSC were transplanted subcutaneously into immunocompetent mice (n=12). Undifferentiated MSC (group A) were compared with osteogenic-induced MSC (group B). Human-specific in situ hybridization and anti-vimentin staining was used to follow MSC after transplantation. Quantitative evaluation of lymphocytes and macrophages was performed as a measure of immunologic rejection. Unloaded scaffolds served as controls (group C). Specimens were harvested at 4 and 8 weeks. RESULTS: Undifferentiated BMSC and ASC were detected in the majority of cases after xenogenic transplantation (group A, a total of 22 out of 24 cases), while osteogenic-induced MSC (group B) could be detected in only three of 24 cases. Quantification of lymphocytes and macrophages revealed significantly higher cell numbers in group B compared with group A (P<0.05). DISCUSSION: Our results suggest that undifferentiated MSC are candidates for non-autologous cell transplantation, while osteogenic-induced MSC seem to be eliminated by the host's immune system. This observation seems independent of the origin of MSC and applies to BMSC and ASC.

[Management of ipsilateral femoral neck and shaft fractures]. / Management von Kombinationsfrakturen des Femurschafts und des proximalen Femurs.

PURPOSE: The combination of ipsilateral femoral neck and shaft fractures remains a treatment challenge in orthopedic surgery because both fracture types constitute separate entities and require specific treatment concepts. MATERIAL AND METHODS: In a case control study, incidence, treatment strategies, and outcomes of this injury were analyzed. All patients with femoral fractures treated between 1 January 2001 and 31 July 2007 at a level I trauma center were included in the study. RESULTS: Twenty-one out of 1,935 patients (1.1%) sustained 22 combined fractures of the femoral neck and shaft. Also considering the combination of femoral shaft fractures with fractures of the acetabulum and the distal femur (knee), the proportion of chain injuries of the femur was 3.1%. The rate of multiply injured patients in the group of patients with ipsilateral femoral neck and shaft fractures was 64%. The majority of the patients could be treated with a single implant for both fracture components. The leading fracture component was the femoral neck fracture in eight cases. All fractures consolidated after 4.7 months on average; one pseudarthrosis of the femoral neck was observed. All fractures were discovered in the course of primary diagnostic measures; in 73% of the patients, a computed tomography (CT) body scan was done. Fifty-nine percent of the patients with ipsilateral femoral neck and shaft fractures received primary definitive operative care. Complications included two torsional failures that needed correction and one case of postoperative infection that was easily treated. CONCLUSION: Treatment of ipsilateral femoral neck and shaft fractures is still demanding, but diagnosis has improved with regular use of CT body scans in the management of multiply injured patients. Furthermore, possibilities for operative treatment have been advanced by the introduction of the long proximal femoral nail and the antegrade femoral nail, two implants supporting stabilization of these fracture entities.

Comparison of cellular functionality of human mesenchymal stromal cells and PBMC.

BACKGROUND: Human mesenchymal stromal cells (MSC) and PBMC play significant roles in repair processes following inflammation. Mechanisms of recruitment are still under investigation. METHODS AND RESULTS: MIP-1alpha induced the chemotactic migration of MSC but not of PBMC. Correlating with this, 7.7% of MSC expressed the chemokine receptor CCR-1, as shown by FACS analysis. In contrast, PBMC did not express CCR-1 or CCR-2 but did express CXCR-4 (81.9%) and CCR-7 (42.2%). Setum induced the chemotaxis of both cell types, and zymosan activation increased the migration of PBMC but not of MSC. Corresponding with this, C5a induced the migration of PBMC but not of MSC. Dose-dependent and -specific adhesion to fibronectin, fibrinogen, collagen type I and collagen type II could be demonstrated for MSC; in contrast, PBMC did not adhere to any of the investigated proteins. Real-time PCR of receptor expression revealed a 12.2-fold higher expression of alphav in MSC compared with PBMC. Incubation of MSC with tumor necrosis factor-alpha (TNFalpha) induced NFkappaB activation and increased the chemotactic response to serum and adhesion to fibronedtin. DISCUSSION: Chemotaxis and adhesion are crucial and differing cell fundtons of MSC and PBMC.

Mesenchymal stem cells maintain TGF-beta-mediated chondrogenic phenotype in alginate bead culture.

This article addresses the stability of chondrogenic phenotype and the transdifferentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) at distinct stages of differentiation. Differentiated MSCs were expected to maintain cartilage-like gene expression pattern in the absence of any chondrogenic growth factor or in the presence of osteogenic signals. MSCs encapsulated in alginate beads were treated with transforming growth factor (TGF)-beta 3 for 3, 6, or 14 days and then cultured in absence of TGF-beta for the remainder of the 2-week culture period. Additionally, cells were cultured in osteogenic medium after TGF-beta-mediated chondroinduction. Gene expression of col2a1, aggrecan, COMP, alkaline phosphatase (AP), and correlating protein synthesis was analyzed. After short-term stimulation with TGF-beta, MSCs maintained a chondrogenic phenotype. Chondrogenic gene expression and protein synthesis directly correlated with the extent of stimulation time and the concentration of TGF-beta. Pretreatment with TGF-beta could prevent AP mRNA expression of encapsulated MSCs. TGF- beta stimulation within the first 3 days of culture seems to be crucial for the expression of a chondrogenic phenotype. Fully differentiated and encapsulated MSCs are not able to transdifferentiate into osteoblasts. These findings give rise to a better understanding of the behavior of cartilage grafts affected by local factors of osteochondral transplantation sites in vivo.

Differential expression pattern of extracellular matrix molecules during chondrogenesis of mesenchymal stem cells from bone marrow and adipose tissue.

Adipose-derived adult stem cells (ADASCs) or bone marrow-derived mesenchymal stem cells (BMSCs) are considered as alternative cell sources for cell-based cartilage repair due to their ability to produce cartilage-specific matrix. This article addresses the differential expression pattern of extracellular matrix (ECM) molecules in BMSCs or ADASCs following chondrogenic differentiation. Human BMSCs or ADASCs were encapsulated in alginate and cultured in TGF-beta1-containing medium for 2 or 3 weeks. Chondrospecific mRNA expression was analyzed and alternative splicing of alpha(1)-procollagen type II mRNA was monitored via reverse transcriptase-polymerase chain reaction (RT-PCR). Corresponding ECM synthesis was demonstrated using immunohistochemistry. After chondroinduction, expression of collagen type II, type X, COMP and aggrecan mRNA was 3-15-fold higher than in ADASCs. The type IIA splicing form of alpha(1)-procollagen type II was expressed in both populations, and the type IIB splicing form was exclusively detected in BMSCs. In response to TGF-beta, collagen type II and X were secreted more strongly by BMSCs than by ADASCs. BMSCs express a more mature phenotype than ADASCs after chondroinduction. TGF-beta1 induces alternative splicing of the alpha(1)-procollagen type II transcript in BMSCs, but not in ADASCs. These findings may direct the development of a cell-specific culture environment either to prevent hypertrophy in BMSCs or to promote chondrogenic maturation in ADASCs.