Biomedical subjects

Nehemia Blumberg

Publications and source records attributed to Nehemia Blumberg.

5 recordsLinked to original sources

PubMed2006

The femoral head expandable peg: improved periimplant bone properties following expansion in a cadaveric model.

PURPOSE: The femoral head expandable peg offers a new concept of bone-device purchase treating proximal femur fractures. We describe the expansion influence on both the periimplant bone properties and the intraosseous pressure. METHODS: A 10 x 8 mm cannulated peg consisting of a stainless steel oval-shaped transversely sectioned rod was tested on 13 femoral heads retrieved from patients with subcapital fracture treated by hemiarthroplasty. Normal saline solution was used to expand the diameter of its membrane from 7.8 to 10.5 mm, resulting in abutment of the distal peg to the compacted cancellous bone of the femoral head. The intraosseous pressure was monitored using a 1.4 mm drill-hole. RESULTS: Dual-energy X-ray absorptiometry and microradiography demonstrated increased periimplant bone density following peg expansion, without significant increase in the intraosseous pressure. CONCLUSION: The new implant afforded improved periimplant bone density, less trabecular damage and preservation of bone stock, all contributing to reliable biomechanical support and potentially decreasing the high complication rate following screw fixation in osteoporotic femora. Further studies are needed in order to establish clinical safety and efficacy.

Absorptiometry, Photon↗

PubMed2006

The importance of the valgus stress test in the diagnosis of posterolateral instability of the knee.

BACKGROUND: The diagnosis of posterolateral instability of the knee is often based on a typical indirect mechanism of injury, a history of "giving way" and a positive dial test. Our search of the English literature revealed no mention of including the valgus stress test in the diagnostic protocol for posterolateral instability. HYPOTHESIS: Based on our experience, we hypothesised that a medial collateral ligament (MCL) tear will also produce a positive dial test and that a valgus stress test would provide differential diagnostic information. METHODS: The MCL's of 14 fresh cadaveric knees (7 cadavers) were cut to simulate a grade 3 tear, taking care not to damage the medial retinaculum or the posteromedial stabilisers of the knee. The amount of tibial external rotation (the dial test) was measured for each knee before and after transection of the MCL. RESULTS: The results of the dial test after transection of the MCL were similar to those stemming from a solitary injury to the posterolateral corner. There was a significant increase in external rotation of the knee in 30 degrees and 90 degrees of flexion. More over, external rotation in 30 degrees was significantly greater than external rotation in 90 degrees of knee flexion. CONCLUSIONS: Whenever suspecting a posterolateral complex injury, one has to carefully perform a valgus stress test in 0 degrees and 30 degrees. Although the support of a clinical study is needed in order to make a definite conclusion, the dial test is probably not reliable in the presence of medial instability, and alternative diagnostic measures should be used.

Cadaver↗

PubMed2005

The fixion proximal femur nailing system: biomechanical properties of the nail and a cadaveric study.

The treatment of choice for early mobilization of hip fracture is surgery, which traditionally employs side plates and screws or intramedullary nails. We examined the biomechanical properties of a new proximal femoral nail system. The new expandable Fixion proximal femur nailing (PFN) system, made of stainless-steel alloy, consists of a nail, a peg and an anti-rotation pin. Upon positioning, the nail and peg are expanded to their maximal diameter. The current biomechanical study investigated: nail bending strength and stiffness, fatigue properties and hip peg strength. A cadaveric study that determined the effect of the expandable peg on the femoral head included subsidence testing, pull and torsion testing and intra-osseous pressure (IOP) measurements before and after expansion. Biomechanical properties of the new nail met ASTM F384 guideline requirements. The cadaver study yielded equivalent results for the pullout test between the peg and the hip screw, but found the peg superior in the torsion strength test. IOP during peg insertion and expansion was substantially lower than the threshold pressure that causes avascular necrosis. The biomechanical tests found the new system to be safe and able to provide good abutment of the nail to the bone. We conclude that the Fixion PFN system proved to be an effective proximal femur fracture fixation device.

Alloys↗

PubMed2003

[Updates in osteogenesis imperfecta].

Osteogenesis Imperfecta, a heterogenous group of inherited disorders, is characterized by both bone fragility and low bone mass. Since the Sillence classification of the disease, significant progress has been made in understanding the molecular, histological and genetical pathogenesis of the disease, and it led to expanded nosology. The multidisciplinary approach including rehabilitation, medications and surgery, may significantly improve the quality of life and prolong life expectancy.

Humans↗

PubMed2002

Avulsion of the triceps tendon during acceleration stress.

The authors present a rare case of triceps tendon avulsion associated with +5 G-force and muscle straining. Although failure of musculoskeletal system, mainly the cervical spine, secondary to high-G exposure has been reported, this is the first report they have found of a triceps tendon avulsion. Furthermore, unlike other traumatic triceps avulsions reported, the pilot involved had no known predisposing factors. Awareness of the possibility of such an injury must be maintained when a pilot of high performance aircraft presents with elbow pain.

Acceleration↗