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Spinal metastatic tumor is a common problem and represents a challenging problem in oncology practice. Patients with osteolytic metastases often suffer from intractable local and/or radicular pain. Percutaneous vertebroplasty is a minimally invasive, radiologically guided procedure whereby bone cement is injected into structurally weakened vertebrae to provide immediate biomechanical stability. Vertebroplasty is also used to relieve pain by stabilizing metastatically compromised vertebrae that are at risk of pathological burst fracture. In this retrospective study, a total of 57 patients (78 vertebrae) with spinal metastatic tumor were treated with PMMA vertebroplasty. The mean value of the visual analogue scale (VAS) was 8.1 +/- 0.67 preoperatively, and significantly decreased to 3.8 +/- 1.9 (1-8, p < 0.015) one day after vertebroplasty. The mean VAS value 6 months after vertebroplsty was 2.8 +/- 2.0 (p < 0.001). Mean injected bone cement amount in our study is 5.16 +/- 1.6 mL. The complication rate is about 21.8%, bone cement extravasation without neurological deficit is the most common complication. No new or adjacent vertebral fracture has occurred in more than 2 years follow-up. Percutaneous vertebroplasty is a minimally invasive procedure that offers a remarkable advantage of effective and immediate pain relief with few complications.

Mammalian neurofilaments are assembled from the light (NF-L), midsized (NF-M), and heavy (NF-H) neurofilament proteins. While NF-M and NF-H cannot self-assemble into homopolymers, the data concerning NF-L has been more contradictory. In vitro bovine, porcine, and murine NF-L can homopolymerize in the absence of other subunits. However, in vivo studies suggest that neither rat nor mouse NF-L can form filaments when transfected alone into cells lacking endogenous intermediate filaments. By contrast, human NF-L forms homopolymers in similar cell lines. Recently we generated mice with null mutations in the NF-M and NF-H genes. To determine if mouse NF-L can homopolymerize in mouse axons, NF-M and NF-H null mutants were bred to create a line of double mutant animals. Here we show that axons in NF-M/H double mutant animals are largely devoid of 10-nm filaments. Instead, the axoplasm is transformed to a microtubule-based cytoskeleton-although the lack of any increase in tubulin levels per unit length of nerve or of increases in microtubule numbers relative to myelin sheath thickness argues that microtubules are not increased in response to the loss of neurofilaments. Thus in vivo rodent neurofilaments are obligate heteropolymers requiring NF-L plus either NF-M or NF-H to form a filamentous network.