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Biomedical subjects

Meir Liebergall

Publications and source records attributed to Meir Liebergall.

At least 19 recordsLinked to original sources
PubMed2006

A short plate compression screw with diagonal bolts--a biomechanical evaluation performed experimentally and by numerical computation.

INTRODUCTION: Decreasing the length of the side plate of the dynamic hip screw would theoretically allow a smaller surgical incision, a shorter surgical time, decreased operative blood loss and minimal periosteal stripping. A new design of a very short plate dynamic hip screw based on two diagonal screws has been developed. Our study compares the new design and the four-hole side plate in respect to mechanical properties and bio-mechanical outcomes utilizing the Finite Element Analysis method. METHODS: Four pairs of fresh frozen cadaveric femora were extracted from male corpses aged 25-43 years (mean 34.8). One femur of each pair was fixated by means of the new system and the other by means of the conventional design. Mechanical loading was applied to all four pairs. The decline which occurred during the periodical loadings and the breakage loads of fixated bones were measured. Mechanical performance and probability of failure was assessed by conducting a mathematical analysis using the finite element method. FINDINGS: The average deflection under excessive cyclic loading was 33% higher in the bones fixated with the very short plate-dynamic hip screw device than in those fixated with the conventional dynamic hip screw. The average load failure during the collapse-loading test was 3120N for the very short plate-dynamic hip screw as compared to 4160N for the regular device. Mechanical testing did not provide decisive results regarding failure. The mathematical analysis performed indicated that the maximal stress in the very short plate-dynamic hip screw reached values 3-4-fold higher than in the regular dynamic hip screw. INTERPRETATION: Although the new design offers a minimally invasive approach to subtrochanteric femur fracture fixation, it was found to have insufficient biomechanical performance resulting in high probability of mechanical failure. The authors believe that the finite element method may have the potential to serve as an additional clinical tool for performing surgical preplanning and assist in decision making.

Adult↗
PubMed2006

Osteogenic differentiation of noncultured immunoisolated bone marrow-derived CD105+ cells.

The culture expansion of human mesenchymal stem cells (hMSCs) may alter their characteristics and is a costly and time-consuming stage. This study demonstrates for the first time that immunoisolated noncultured CD105-positive (CD105(+)) hMSCs are multipotent in vitro and exhibit the capacity to form bone in vivo. hMSCs are recognized as promising tools for bone regeneration. However, the culture stage is a limiting step in the clinical setting. To establish a simple, efficient, and fast method for applying these cells for bone formation, a distinct population of CD105(+) hMSCs was isolated from bone marrow (BM) by using positive selection based on the expression of CD105 (endoglin). The immunoisolated CD105(+) cell fraction represented 2.3% +/- 0.45% of the mononuclear cells (MNCs). Flow cytometry analysis of freshly immunoisolated CD105(+) cells revealed a purity of 79.7% +/- 3.2%. In vitro, the CD105(+) cell fraction displayed significantly more colony-forming units-fibroblasts (CFU-Fs; 6.3 +/- 1.4) than unseparated MNCs (1.1 +/- 0.3; p < .05). Culture-expanded CD105(+) cells expressed CD105, CD44, CD29, CD90, and CD106 but not CD14, CD34, CD45, or CD31 surface antigens, and these cells were able to differentiate into osteogenic, chondrogenic, and adipogenic lineages. In addition, freshly immunoisolated CD105(+) cells responded in vivo to recombinant bone morphogenetic protein-2 by differentiating into chondrocytes and osteoblasts. Genetic engineering of freshly immunoisolated CD105(+) cells was accomplished using either adenoviral or lentiviral vectors. Based on these findings, it is proposed that noncultured BM-derived CD105(+) hMSCs are osteogenic cells that can be genetically engineered to induce tissue generation in vivo.

Adolescent↗
PubMed2006

Sciatic nerve palsy due to hematoma after thrombolysis therapy for acute pulmonary embolism after total hip arthroplasty.

Sciatic nerve paralysis as a complication of bleeding due to hip surgery is a rare entity. The use of thrombolysis and full-dose heparin administration for the treatment of massive pulmonary embolism increase the risk for developing major bleeding. Prompt recognition and intervention in this condition are warranted. A case of sciatic nerve palsy due to expanding thigh hematoma as a complication of thrombolytic therapy for pulmonary embolism after total hip arthroplasty is presented with a literature review. Although rare, this complication should be promptly recognized and immediate decompression should take place because of the favorable results of the early treatment.

Acute Disease↗
PubMed2006

Nucleofection-based ex vivo nonviral gene delivery to human stem cells as a platform for tissue regeneration.

There are several gene therapy approaches to tissue regeneration. Although usually efficient, virusbased approaches may elicit an immune response against the viral proteins. An alternative approach, nonviral transfer, is safer, and can be controlled and reproduced. We hypothesized that in vivo bone formation could be achieved using human mesenchymal stem cells (hMSCs) nonvirally transfected with the human bone morphogenetic protein-2 (hBMP-2) or -9 (hBMP-9) gene. Human MSCs were transfected using nucleofection, a unique electropermeabilization-based technique. Postnucleofection, cell viability was 53.6 +/- 2.5% and gene delivery efficiency was 51% to 88% (mean 68.2 +/- 4.1%), as demonstrated by flow cytometry in enhanced green fluorescent protein (EGFP)-nucleofected hMSCs. Transgene expression lasted longer than 14 days and was very low 21 days postnucleofection. Both hBMP-2- and hBMP-9-nucleofected hMSCs in culture demonstrated a significant increase in calcium deposition compared with EGFP-nucleofected hMSCs. Human BMP-2- and hBMP-9-nucleofected hMSCs transplanted in ectopic sites in NOD/SCID mice induced bone formation 4 weeks postinjection. We conclude that in vivo bone formation can be achieved by using nonvirally nucleofected hMSCs. This could lead to a breakthrough in the field of regenerative medicine, in which safer, nonviral therapeutic strategies present a very attractive alternative.

Animals↗
PubMed2006

Talc sclerodhesis of persistent Morel-Lavallée lesions (posttraumatic pseudocysts): case report of 4 patients.

Large posttraumatic pseudocysts are infamous for their tendency to recur despite repeated aspiration. The standard practice has been repeated extensive surgical debridement. To avoid the need for such treatment, talc was used to sclerose the lesion in 4 patients treated between 2000 and 2003. The patients were between the ages of 20 and 73 and had thigh and buttock pseudocysts that persisted for an average of 3 months. Talc was administered under fluoroscopic guidance and suction drainage (wall suction followed by a bulb vacuum drainage system) was applied for an average of 12 days. The patients were followed for an average period of 27 months after talc sclerodhesis. All persistent pseudocysts showed an immediate cessation of fluid accumulation in the treated space without reccurence. One case which was complicated by infection, had to be treated twice with talc to cease the accumulation. In this case, the infection recurred, although fluid accumulation did not recur. Talc sclerodhesis proved to be a simple and rapid method of treatment in posttraumatic cases classically treated by repeated and aggressive surgical methods.

Adult↗
PubMed2006

Computerized navigation for the internal fixation of femoral neck fractures.

BACKGROUND: Accurate placement of cannulated screws is essential to ensure secure fixation of femoral neck fractures. We compared computerized navigation and conventional fluoroscopy with regard to the accuracy of screw placement for the fixation of femoral neck fractures. METHODS: We retrospectively compared two groups of twenty consecutive patients with a femoral neck fracture who underwent internal fixation with three cannulated screws. Computer-based navigation was used to guide screw placement in one group, and conventional fluoroscopy was used in the other group. Radiographic evaluation included the measurement of screw parallelism and spread, the calibrated distance from the lesser trochanter, and joint penetration. The follow-up period was two years. The rates of complications in both groups were evaluated. RESULTS: The navigation-assisted group had better screw parallelism and greater spread of the screws. There was a tendency for fewer reoperations and significantly fewer overall complications in the patients in whom computerized navigation was used (p < 0.018). CONCLUSIONS: Computerized navigation improves the accuracy of cannulated screw placement in the internal fixation of femoral neck fractures. It may provide better mechanical stability and improved fracture outcome.

Aged↗
PubMed2006

Shrapnel management.

With the increased incidence of terrorism worldwide, it is important for surgeons to understand the role of shrapnel injury in mass casualty events. Several diagnostic modalities are available, including plain radiography, computed tomography, ultrasound, angiography, and computerized surgical navigation based on real-time acquisition of fluoroscopic data. Shrapnel management techniques are selected based on the following chronologic phases: acute, subacute, and late.

Humans↗
PubMed2006

Blast and penetrating fragment injuries to the extremities.

Blast injury to the extremities is the most common form of injury in recent military campaigns and in civilian terror attacks. Most orthopaedic trauma is caused by the secondary effect of blast--penetrating fragment injury. Timely wound débridement and excision of contaminated or avascular tissue, along with prevention of sepsis, are crucial to managing extremity injury. Late reconstruction and functional results are very challenging for the surgical team to achieve.

Blast Injuries↗
PubMed2005

Percutaneous compression plating for intertrochanteric fractures. Surgical technique, tips for surgery, and results.

OBJECTIVE: Fixation of intertrochanteric fractures by a minimally invasive technique using the Percutaneous Compression Plate (PCCP) allowing anatomic reduction and immediate postoperative weight bearing. INDICATIONS: Intertrochanteric fractures. CONTRAINDICATIONS: Intertrochanteric fractures that cannot be reduced by closed manipulation, subtrochanteric and reverse oblique fractures (AO/OTA 31-A3). SURGICAL TECHNIQUE: Placement of patient on a fracture table with a posterior reduction device (PORD) supporting the fracture. Reduction of the fracture by closed manipulation. Percutaneous insertion of the plate through a lateral proximal incision. Adaptation of the plate to the lateral aspect of the proximal femoral shaft with a bone clamp inserted through a second, more distal incision. Insertion of telescoping compression neck screw through the plate into the neck and securing of plate to the femoral shaft with three additional screws. Finally, completion of fracture fixation with second neck screw. RESULTS: Of 130 patients with intertrochanteric fractures treated using the described technique at the Orthopedic Surgery Department Hadassah University Hospital, Jerusalem, Israel, between May 2000 and December 2001, 108 were available for this study. Patients' age averaged 81 years (+/- 8 years). Mean surgical time was 67 min and mean hospital stay 11.5 days. 40% of patients did not require a transfusion during hospitalization, while 8.3% needed more than three units of packed cells. Complications occurred in four patients: two implant failures that were successfully revised with a Compression Hip Screw, one nonunion treated with hip arthroplasty; the fourth patient had a shortening of 3 cm needing a heel lift. Three patients developed an infection, one requiring surgical debridement.

Aged↗
PubMed2005

Percutaneous compression plating versus compression hip screw fixation for the treatment of intertrochanteric hip fractures.

Percutaneous compression plate (PCCP) devices are used for the fixation of intertrochanteric hip fractures by a minimally invasive technique. One hundred and eight patients who underwent this procedure were retrospectively compared with 155 patients who underwent compression hip screw (CHS) fixation. The general characteristics of the two groups, including age, sex, side of injury and co-morbidities assessed by the ASA score were similar. The operative time was significantly shorter in the PCCP group (67 versus 87 min, p=0.00). Postoperative blood transfusions were not required in 40% of the patients in the PCCP group compared to 24% of the patients in the CHS group (p<0.01). The rate of systemic postoperative complications was lower in the PCCP group (p=0.02) both in univariate and multivariate analyses. A considerable reduction was observed in cardiovascular complications (OR=3.1, p<0.05). Length of hospitalisation, implant failure and mortality rates were not significantly different between the two study groups. We conclude that the PCCP device offers several advantages over CHS device and may improve the current treatment of intertrochanteric hip fractures while maintaining a similar success rate in fracture fixation.

Aged↗
PubMed2005

Murine spinal fusion induced by engineered mesenchymal stem cells that conditionally express bone morphogenetic protein-2.

OBJECT: The authors hypothesized that spinal fusion can be achieved and monitored by using cell-mediated gene therapy. Mesenchymal stem cells (MSCs) genetically engineered to express recombinant human bone morphogenetic protein-2 (rhBMP-2) conditionally, were implanted into the paraspinal muscles of mice to establish spinal fusion. The goal was to demonstrate an MSC-based gene therapy platform in which controlled gene expression is used to obtain spinal fusion in a murine model. METHODS: Mesenchymal stem cells expressing the rhBMP-2 gene were injected into the paravertebral muscle in mice. Bone formation in the paraspinal region was longitudinally followed by performing micro-computerized tomography scanning, histological studies, and an analysis of osteocalcin expression to demonstrate the presence of engrafted engineered MSCs. The minimal period of rhBMP-2 expression by the engineered MSCs required to induce fusion was determined. The results of this study demonstrate that genetically engineered MSCs induce bone formation in areas adjacent to and touching the posterior elements of the spine. This newly formed bone fuses the spine, as demonstrated by radiological and histological studies. The authors demonstrate that injected cells induce active osteogenesis at the site of implantation for up to 4 weeks postinjection. They found that a 7-day induction of rhBMP-2 expression in genetically engineered MSCs was sufficient to form new bone tissue, although the quantity of this bone increased as longer expression periods were implemented. CONCLUSIONS: After their injection genetically engineered MSCs can efficiently form new bone in the paraspinal muscle of the mouse to obtain spinal fusion. The extent and quantity of this newly formed bone can be monitored by controlling the duration of rhBMP-2 gene expression.

Animals↗