Successful Two-Stage Exchange Arthroplasty for Periprosthetic Infection Following Total Knee Arthroplasty: The Impact of Timing on Eradication of Infection.

Background: Periprosthetic joint infection (PJI) represents a serious complication following total knee arthroplasty. In the setting of chronic infections, the two-staged approach has traditionally been the preferred treatment method. The aim of this study was to determine the optimal period of rest between the first and second stage. Furthermore, we analyzed potentially outcome-relevant parameters, such as general and local conditions and the presence of difficult-to-treat or unidentified microorganisms, with regard to their impact on successful treatment of PJI. Patients and Methods: We performed a retrospective analysis of prospectively collected data for all patients treated for PJI at our institution. Seventy-seven patients who had undergone two-stage revision arthroplasty for PJI of the knee were included into the study. Antibiotic-loaded cement spacers were used for all patients. Results: After a median follow-up time of 24.5 months, infection had reoccurred in 14 (18.7%) patients. A prolonged spacer-retention period of more than 83 days was related to a significantly higher proportion of reinfections. Furthermore, significant compromising local conditions of the prosthetic tissue and surrounding skin, as well as repeated spacer-exchanges between first- and second-stage surgery, negatively influenced the outcome. Neither the patients' age nor gender exerted a significant influence on the outcome regarding reinfection rates for patients' age or gender. Conclusions: We observed the best outcome regarding infection control in patients who had undergone second-stage surgery within 12 weeks after first-stage surgery. Nearly 90% of these patients stayed free from infection until the final follow-up. An increased number of performed spacer-exchanges and a bad local extremity grade also had a negative impact on the outcome.

Talocalcaneal Coalition Including Open Comminuted Calcaneal Fracture; A Case Report and Literature Review.

Tarsal coalition is an often unrecognised cause of foot and ankle pain and represents a congenital osseous, cartilaginous or fibrous connection between two or more tarsal bones. Fractures in combination with tarsal coalitions are rarely described in the literature. We report the case of a 43-year-old male patient with a talocalcaneal coalition who sustained an open comminuted calcaneal fracture and a closed transverse cuboid fracture. Due to the asymptomatic tarsal coalition and the already firmly fixed subtalar joint, the patient was treated with open reduction and internal fixation (ORIF) with satisfactory outcomes instead of ORIF in combination with subtalar arthrodesis. Ten months after the trauma, the patient was satisfactory and could return to his regular work. There is currently no evidence for the gold standard treatment of calcaneal fractures with combined tarsal coalitions. Due to the satisfactory results of this case, authors conclude that in case with prior asymptomatic coalitions, singular ORIF without subtalar arthrodesis may be performed.

Scaphoid screw placement under minimal radiation exposure.

BACKGROUND: Percutaneous scaphoid fixation through either a volar or dorsal approach has the advantage of minor soft tissue damage compared with ORIF, and faster fracture union compared with conservative treatment. However, this technique demands highly intraoperative reliance on X-ray control, including increased radiation exposure and all associated side effects. PURPOSE: To test the possibility and efficacy of volar percutaneous scaphoid screw placement under minimalradiation exposure. METHODS: The sample included 20 hands (seven left, 13 right) from human adult cadavers. For this study, the utilised wrists were assumed to have non-displaced scaphoid fractures. Using a percutaneous approach, a 2-mm Kirschner wire (K-wire) was advanced to the distal pole of the scaphoid and placed in a 45° horizontal and vertical angle under monitoring with the C-arm. The K-wire was inserted blindly alongside the estimated length of the scaphoid. Following K-wire insertion, four X-rays were taken to depict K-wire positioning and to assess positioning alongside the axis of the scaphoid and K-wire protrusion. The rating scale comprised 1 (good), 2 (moderate) or 3 (poor). RESULTS: All tested radiographic views were evaluated with a median of 2 points (moderate position) regardingplacement alongside the scaphoid axis. CONCLUSION: Our results indicate that percutaneous scaphoid fixation with the guide wire placed in a 45° horizontal and vertical angle enables primary moderate positioning, which may lead to quicker adjustment to the ideal position and a decrease of radiation exposure.

Characterization of Senescence of Culture-expanded Human Adipose-derived Mesenchymal Stem Cells.

BACKGROUND AND OBJECTIVES: Adipose-derived mesenchymal stem cells (ADSCs) are promising candidates in regenerative medicine. The need for in vitro propagation to obtain therapeutic quantities of the cells imposes a risk of impaired functionality due to cellular senescence. The aim of the study was to analyze in vitro senescence of previously cryopreserved human ADSCs subjected to serial passages in cell culture. METHODS AND RESULTS: ADSC cultures from 8 donors were cultivated until proliferation arrest was reached. A gradual decline of ADSC fitness was observed by altered cell morphology, loss of proliferative, clonogenic and differentiation abilities and increased ß-galactosidase expression all of which occurred in a donor-specific manner. Relative telomere length (RTL) analysis revealed that only three tested cultures encountered replicative senescence. The presence of two ADSC subsets with significantly different RTL and cell size was discovered. The heterogeneity of ADSC cultures was supported by the intermittent nature of aging seen in tested samples. CONCLUSIONS: We conclude that the onset of in vitro senescence of ADSCs is a strongly donor-specific process which is complicated by the intricate dynamics of cell subsets present in ADSC population. This complexity needs to be carefully considered when elaborating protocols for personalized cellular therapy.

Growth Properties and Pluripotency Marker Expression of Spontaneously Formed Three-dimensional Aggregates of Human Adipose-derived Stem Cells.

BACKGROUND AND OBJECTIVES: Recent findings suggest that therapeutic potential of mesenchymal stem cells (MSCs) could be increased through aggregation into three-dimensional (3D) bodies, and different culture methods have been employed to obtain 3D spheroids of MSCs. In the current study we report accidentally encountered spontaneous formation of adipose-derived stem cell (ASC) bodies in standard ASC culture of a single donor. METHODS AND RESULTS: Human ASCs from passages 1 to 3, cultured in a medium containing 5% autologous serum (AS), spontaneously clustered and formed floating 3D bodies. After a transfer of floating ASC bodies onto new adherent plastic dish, they attached to the surface and gradual migration of spindle-shaped ASCs out of the bodies was detected. A substitution of AS with allogeneic sera did not hinder this ability, but commercial medium containing fetal bovine serum delayed the process. Substantial part of ASCs surrounding transferred ASC bodies showed alkaline phosphatase (AP) activity, while ASC aggregates were AP negative. Similar 3D bodies formed when ASCs were grown on an uncoated glass surface. These ASC aggregates as well as clusters of ASCs, where formation of the 3D bodies is initiated, expressed pluripotency marker NANOG, but the expression of OCT4A was not detected. CONCLUSIONS: Obtained results suggest that spontaneously formed ASC aggregates may represent a more primitive cell subpopulation within the individual ASC culture. The ability to form 3D aggregates, the expression of NANOG, and the lack of the AP activity may be used to enrich ASC cultures with potentially more primitive cells serving as an excellent basis for therapeutic applications.

Characterization of human adipose-derived stem cells cultured in autologous serum after subsequent passaging and long term cryopreservation.

The aim of this study was to evaluate human adipose-derived stem cells (ASCs) from passage 2 (P2) to P8 cultured in medium containing 5% autologous serum (AS) after a long-term cryopreservation with regards to their surface marker expression, differentiation potential, and immunosuppressive effect in vitro. 8-color flow cytometry and real time PCR were used to determine mesenchymal stem cell (MSC) surface marker expression on ASCs from various passages. In vitro differentiation ability and immunomodulatory properties of ASCs were also tested. Flow cytometry showed that all ASCs express typical MSC markers CD29, CD44, CD73, CD90, CD105 simultaneously, but do not express such markers as HLA-DR, CD34, CD14, CD19, and CD45. Furthermore, median fluorescence intensity of positive cell surface markers increased with each subsequent passage indicating the accumulation of protein expression. The multilineage differentiation demonstrated the ability of ASCs from P6 to efficiently differentiate into adipocytes and chondrocytes, but their potential of osteogenic differentiation was diminished. Data from co-culture of ASCs and autologous peripheral blood mononuclear cells (PBMNCs) indicated that ASCs from P3, P6, and P9 significantly reduce the proliferation of PBMNCs at ASCs:PBMNCs ratio 1:1 and this suppression is dose dependent. This study demonstrated that ASCs from P2 to P8, cultured in the presence of AS, represent a highly homogeneous cell population with a peak accumulation of MSC surface proteins at P5 possessing multilineage differentiation ability and significant immunosuppressive properties after double freezing and more than 4 years of cryopreservation.