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Anterior cruciate ligament (ACL) reconstruction involves the replacement of the torn ligament with a new graft, often a hamstring tendon (HT). Described as similar, the ACL and HT have intrinsic differences related to their distinct anatomical locations. From a cellular perspective, identifying these differences represents a step forward in the search for new cues that enhance recovery after the reconstruction. The purpose of this study was to characterize the phenotype and multilineage potential of ACL- and HT-derived cells. ACL- and HT-derived cells were isolated from tissue harvest from patients undergoing total knee arthroplasty (TKA) or ACL reconstruction. In total, three ACL and three HT donors were investigated. Cell morphology, self-renewal potential (CFU-F), surface marker profiling, expression of tendon/ligament-related markers (PCR) and multilineage potential were analysed for both cell types; both had fibroblast-like morphology and low self-renewal potential. No differences in the expression of tendon/ligament-related genes or a selected set of surface markers were observed between the two cell types. However, differences in their multilineage potential were observed: while ACL-derived cells showed a high potential to differentiate into chondrocytes and adipocytes, but not osteoblasts, HT-derived cells showed poor potential to form adipocytes, chondrocytes and osteoblasts. Our results demonstrated that HT-derived cells have low multilineage potential compared to ACL-derived cells, further highlighting the need for extrinsic signals to fully restore the function of the ACL upon reconstruction. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)

Background: The human body has an extensive capacity to regenerate bone tissue after trauma. However large defects such as long bone fractures of the lower limbs cannot be restored without intervention and often lead to nonunion. Therefore, the aim of the present study was to assess the pool and biological functions of human mesenchymal stromal cells (hMSCs) isolated from different bone marrow locations of the lower limbs and to identify novel strategies to prime the cells prior to their use in bone fracture healing. Following, bone marrow from the ilium, proximal femur, distal femur and proximal tibia was aspirated and the hMSCs isolated. Bone marrow type, volume, number of mononuclear cells/hMSCs and their self-renewal, multilineage potential, extracellular matrix (ECM) production and surface marker profiling were analyzed. Additionally, the cells were primed to accelerate bone fracture healing either by using acoustic stimulation or varying the initial hMSCs isolation conditions., Results: We found that the more proximal the bone marrow aspiration location, the larger the bone marrow volume was, the higher the content in mononuclear cells/hMSCs and the higher the self-renewal and osteogenic differentiation potential of the isolated hMSCs were. Acoustic stimulation of bone marrow, as well as the isolation of hMSCs in the absence of fetal bovine serum, increased the osteogenic and ECM production potential of the cells, respectively., Conclusion: We showed that bone marrow properties change with the aspiration location, potentially explaining the differences in bone fracture healing between the tibia and the femur. Furthermore, we showed two new priming methods capable of enhancing bone fracture healing.

Mesenchymal stromal cells are present in very low numbers in the bone marrow, necessitating their selective expansion on tissue culture plastic prior to their use in tissue-engineering applications. MSC expansion is laborious, time consuming, unphysiological and not economical, thus calling for automated bioreactor-based strategies. We and others have shown that osteogenic grafts can be cultured in bioreactors by seeding either 2D-expanded cells or by direct seeding of the mononuclear fraction of bone marrow. To further streamline this protocol, we assessed in this study the possibility of seeding the cells onto porous calcium phosphate ceramics directly from unprocessed bone marrow. Using predetermined volumes of bone marrow from multiple human donors with different nucleated cell counts, we were able to grow a confluent cell sheath on the scaffold surface in 3 weeks. Cells of stromal, endothelial and haematopoietic origin were detected, in contrast to grafts grown from 2D expanded cells, where only stromal cells could be seen. Upon implantation in nude mice, similar quantities of bone tissue were generated as compared to that obtained by using the conventional number of culture expanded cells from the same donor. We conclude that human osteogenic grafts can be efficiently prepared by direct seeding of cells from unprocessed bone marrow., (Copyright © 2011 John Wiley & Sons, Ltd.)

Human mesenchymal stromal cells (hMSCs) represent an attractive cell source for clinic applications. Besides being multi-potent, recent clinical trials suggest that they secrete both trophic and immunomodulatory factors, allowing allogenic MSCs to be used in a wider variety of clinical situations. The yield of prospective isolation is however very low, making expansion a required step toward clinical applications. Unfortunately, this leads to a significant decrease in their stemness. To identify the mechanism behind loss of multi-potency, hMSCs were expanded until replicative senescence and the concomitant molecular changes were characterized at regular intervals. We observed that, with time of culture, loss of multi-potency was associated with both the accumulation of DNA damage and the respective activation of the DNA damage response pathway, suggesting a correlation between both phenomena. Indeed, exposing hMSCs to DNA damage agents led to a significant decrease in the differentiation potential. We also showed that hMSCs are susceptible to accumulate DNA damage upon in vitro expansion, and that although hMSCs maintained an effective nucleotide excision repair activity, there was a progressive accumulation of DNA damage. We propose a model in which DNA damage accumulation contributes to the loss of differentiation potential of hMSCs, which might not only compromise their potential for clinical applications but also contribute to the characteristics of tissue ageing., (© 2009 The Authors Journal compilation © 2010 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.)

To render polymeric materials osteoinductive, nano-sized calcium phosphate apatite particles (CaP) were introduced into a low molecular weight poly(D,L-lactide). Homogenous composites were made with 10%, 20% and 40% by weight of apatite content while pure polylactide was used as control. Thereafter porous samples (pore size 300-400 microm, 60% porosity) were fabricated and sterilized. In vitro studies showed that calcium ions were released from the composites depending on the apatite content, while surface mineral deposition was observed only on the 40% CaP composites in simulated body fluid (SBF) within 14 days. After 12 weeks of intramuscular implantation in dogs, only the 40% CaP composite implant retained its shape and showed ectopic bone formation within the pores. In conclusion, adding a content of 40% apatite into poly(D,L-lactide) could lead to an osteoinductive material. Future studies will focus on understanding this phenomenon of material-directed osteoinduction in order to develop a promising bone graft substitute.

Introduction: Large inter-donor differences exist in human mesenchymal stem cell (hMSC) yield and the response of these cells to osteogenic stimuli. The source of these differences may be clinical differences in stem cell characteristics between individuals or the aspiration procedure itself., Methods: From a total of 23 donors, we aimed to take 2 consecutive 10-mL aspirates from the same site in 17 donors and in 6 donors we aimed to take a 5-mL and a 20-mL aspirate. The aspiration was stopped either when the syringe was full or when no more bone marrow came through. Mononuclear cell yield (MNC), MSC yield, and differentiation capacity were analyzed for intra-donor and inter-donor variation. We analyzed the effect of the dilution with peripheral blood by drawing 20 mL at once., Results: There was a high correlation between the first and second aspiration volumes, and aspirates with a volume of less than 8 mL showed a large variation in cellular yield. The second 10-mL aspirate, and also 20-mL aspirates, contained a lower concentration of nucleated cells and yielded lower numbers of mesenchymal stem cells. No effect of the aspiration procedure on the biological characteristics of the mesenchymal stem cells was seen., Conclusion: We recommend collection volumes of bone marrow aspirates of at least 8 mL to reduce the risk of obtaining aspirates with low cell numbers. From the same site, a second aspiration or an aspirate of > 10 mL can be drawn without any loss of biological quality due to dilution with peripheral blood.

Background: Maintenance of wire pretension in an Ilizarov external fixator is dependent on the torque applied to the fixation bolts. We therefore measured immediately after surgery the clinically applied torques. The median value was only 10 N m (range 8-14N m). We wondered whether this value is appropriate to maintain the wire pretension and thereby to achieve sufficient fracture stability during dynamic loading of the device for a longer period., Methods: A material testing machine dynamically loaded one wire mounted on one ring. Several configurations were tested., Results: A quick decrease in wire tension to a steady state situation was seen. In the most stable configuration (20 N m wire fixation torque) 50% of the initial 90 kg wire pretension remained after dynamic loading with 200 N. In the least stable configuration (10 N m torque) considerable wire slippage occurred even without loading and no tension remained after loading! No plastic deformation of the wires was observed so loss of wire tension was due to slippage of the wires through the fixation bolts., Interpretation: With the small fixation torques used in clinical practice considerable wire tension is lost even after a few loading cycles. Further research should address the question whether preservation of a higher wire tension during long term loading promotes faster fracture healing.

Background and Objectives: The functional results and the complications after several limb-saving and ablative treatments because of lower extremity bone sarcoma were evaluated., Methods: Seventy-seven surviving patients were evaluated according to the MSTS (American Musculoskeletal Tumor Society) functional rating system. Fifty-two patients had limb-saving and 25 had ablative therapy. Median follow-up was 97 months in the limb-saving group and 112 months in the ablative group., Results: Functional results in the limb-saving group were significantly better than in the ablative group (P = 0.0001). Functional results in patients with tumors about the knee joint were significantly better (P = 0.0064) after limb-saving surgery (i.e., endoprosthesis, knee arthrodesis, or rotationplasty) compared to functional results after ablative surgery (i.e., hip or knee disarticulation or above-the-knee amputation). Complications were 3 times more common after limb-salvage procedures and 4 times more common after endoprosthetic reconstructions compared to after ablative procedures. Complications after limb-saving therapy were fewest in tumors about the knee joint. In 3/28 patients, the endoprosthetic reconstruction had to be converted to an amputation., Conclusions: Functional results were significantly better after limb-saving compared to after ablative therapy. Complications, however, were more common after limb-saving therapy.

The first purpose of this study was to evaluate the saddle prosthesis in patients with periacetabular tumors in terms of the functional results obtained after several postoperative intervals. The second purpose was to evaluate the complications and how they might be prevented in the future. Functional results according to the MSTS functional rating system were evaluated at several postoperative intervals in 15 patients treated with internal hemipelvectomy and reconstruction with the saddle prosthesis because of periacetabular primary (n = 9) or secondary (n = 6) malignancies. All complications were evaluated. Three months postoperatively, 7/9 patients with a primary tumor and 2/4 patients with a secondary tumor were able to walk outside without pain. Median functional results 3 and 6 months postoperatively were 40% and 50%, respectively. Deep infection occurred in 4 patients and fracture of the iliac remnant in 2. Heterotopic ossifications along the interpositional component were seen in 5 patients, but they did not negatively influence the functional outcome. Three (relative) contraindications to reconstruction with the saddle prosthesis could be ascertained: osteoporosis, extended involvement of the iliac wing by tumor, and insufficient soft-tissue quality after previous procedures. (Short-term) functional results after reconstruction with the saddle prosthesis are satisfactory if the above-mentioned contraindications are taken into consideration.

Background and Objectives: The oncologic and functional results in patients treated because of osteosarcoma (OS) were evaluated., Methods: Fifty-one patients with high-grade OS were treated between 1974 and 1996 at our hospital. All patient records were studied, and the surviving patients were evaluated according to the American Musculoskeletal Tumor Society functional rating system. The majority of patients received adjuvant chemotherapy (prior to 1983) or neoadjuvant chemotherapy (from 1983). Until 1987, all patients with extremity OS had ablative surgery; from 1987, the majority had limb-saving surgery. Lung metastases were resected in most cases., Results: Overall 2-year and 5-year disease-free survival (DFS) rates were 27 of 51 and 16 of 42, respectively. Patients with vertebral or pelvic OS or contaminated margins after resection had a very bad outcome. In all other subgroups, including patients with various types of chemotherapy, response to chemotherapy, diameter of tumor, presence or absence of metastatic spread, and location of tumor, a 5-year DFS of about 50% was found. Recurrent disease in patients who had achieved a 2-year disease-free interval was relatively low (4/23 patients)., Conclusions: Survival in our series was worse than in most other studies. A very bad outcome was found in patients with vertebral or pelvic OS or with contaminated margins after resection., (Copyright 1999 Wiley-Liss, Inc.)

Of 91 limb-salvage procedures using prosthetic reconstructions because of primary or metastatic bone and soft-tissue tumors 26 revisions were performed in 16 patients. Revision was due to polyethylene wear (9 cases), aseptic loosening (8 cases), recurrent hip dislocation (3 cases), prosthetic stem fracture (2 cases), infection (2 cases), leg length discrepancy (1 case), and traumatic dislocation of a saddle prosthesis (1 case). The follow-up period for tumor control varied from 1.5 to 22 years with a median of 13.5 years. The follow-up period after the last revision operation varied from 0.5 to 12 years with a median of 3 years. At the last follow-up, the functional results had deteriorated compared with after the primary operation in 5 patients and had improved in 2 patients. In the remaining patients, the results did not change.

This paper describes 29 patients with Ewing's sarcoma of bone treated between 1975 and 1990 at the University of Nijmegen Hospital, Nijmegen, The Netherlands. Osteomyelitis was the primary diagnosis in 24%. Treatment consisted of chemotherapy in combination with surgery and/or radiotherapy. Nine patients received radiotherapy only; five of them died of disease. Five patients underwent an intralesional excision; four of them died of disease. Twelve patients underwent a wide excision; there is no evidence of disease in any of them. Three patients underwent a radical disarticulation; all died of disease. The disease-free survival at 1.5 years was 66%. This figure at 5 years was 55%. After wide excision and reconstruction in tumors of expendable, femoral or radial bones good functional results were obtained in all cases.

Giant cell tumor of bone is a challenging surgical problem due to its mostly aggressive growth with tendency to recur locally, to develop in rare instances pulmonary metastases without histologic evidence of malignant changes, and due to its potential to dedifferentiate into a frankly malignant tumor in a limited number of patients. It is treated in many different ways because of the difficulties in finding a type of treatment with the best functional results without compromising oncologic results. This paper describes 19 patients with giant cell tumor of bone. Following 19 procedures (including 6 intracapsular resections [curettage]) in 17 patients in our hospital only 2 recurrences (10.5%) occurred, both after curettage. Functional results after curettage without recurrence were favorable. Marginal or wide resections did not result in any recurrence, but were functionally inferior to curettage; an exception to the latter was the resection-arthrodesis of the distal radius in one patient.