Biomedical subjects

Z Hoffer

Publications and source records attributed to Z Hoffer.

5 recordsLinked to original sources

PubMed2001

Does anterolateral cage insertion enhance immediate stabilization of the functional spinal unit? A biomechanical investigation.

STUDY DESIGN: The three-dimensional flexibility of six human lumbar functional spinal units was measured after the anterolateral insertion of an interbody cage. OBJECTIVES: To determine whether an interbody cage inserted from an anterolateral direction stabilizes the spine with respect to the intact state and to compare the finding with that from the same cage inserted from an anterior direction. SUMMARY OF BACKGROUND DATA: Several biomechanical studies have shown that interbody cages do not stabilize the spine in extension. It is suspected that this may be caused by the destruction of the anterior longitudinal ligament and anterior anulus fibrosus. METHODS: Six human cadaveric lumbar functional spinal units were tested under pure moments of flexion, extension, bilateral axial rotation, and bilateral lateral bending to a maximum of 10 Nm. The relative intervertebral motions were measured by an optoelectronic camera system with the spinal units in the intact condition, after discectomy, after anterolateral interbody cage stabilization, and with additional translaminar screw fixation. The implant used was a central, porous, contoured implant with endplate fit. The results were compared with those of a previous study, which used the same implant inserted from an anterior direction. RESULTS: The anterolateral cage insertion significantly decreased the motion in comparison with the intact situation in flexion and lateral bending, but not in extension or axial rotation. No differences were found between the anterior and anterolateral insertion approaches in flexion or extension, but differences were observed in axial rotation and lateral bending, in which the anterolateral approach resulted in more motion. Additional translaminar screw fixation reduced motion to below intact levels in all loading directions. None of the surgical procedures introduced asymmetrical behavior. CONCLUSIONS: Anterolateral cage insertion did not stabilize the spine in extension or axial rotation and was not different from the anterior approach in flexion and extension. Additional translaminar screw fixation stabilized in all directions.

Biomechanical Phenomena↗

PubMed2001

Computer-assisted percutaneous transiliac approach to tumorous malformation of the sacrum.

The object of this article is to present a new, minimally invasive, percutaneous image-guided technique for surgery of tumorous malformation of the sacrum. Using one of the available CAS systems, we developed a navigable working tube through which various surgical tools may be very precisely introduced into the tumorous malformation. The tube allows us to obtain histological samples and also perform tumor resections. For sacral procedures, the working tube was introduced percutaneously into the affected area of the sacrum through the sacroiliac joint with computer assistance. For successful matching, small titanium screws were inserted into the sacrum and pelvis percutaneously before CT examination to give precise landmark points. We have used the method in 12 cases. The aim of the surgery in biopsy cases was to obtain samples for histological diagnoses of unknown tumors. In the cases of tumor resection (all were metastatic), the indication was to obtain neurological decompression and decreased local pain. The pain response was very effective in all cases. The transiliac percutaneous approach to the sacrum has proven to be a safe and well-designed procedure. It can even be performed under local anesthesia, and is thus a very effective minimally invasive tool for obtaining pain relief in cases of sacral metastasis involving the first, second, and third segments.

Humans↗

PubMed2000

Erratum

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Journal Article↗

PubMed2000

A comparative biomechanical investigation of anterior lumbar interbody cages: central and bilateral approaches.

BACKGROUND: Some biomechanical studies have been performed to evaluate the stabilization provided by interbody cages, but there are virtually no comparative data for the different designs. Furthermore, most investigators have used animal models, which may have led to different results due to morphological variation in the end plates and articular facets. The objectives of the current study were to evaluate whether two different anterior cage designs (BAK and SynCage) performed differently with respect to immediate stabilization of the spine, whether the cages stabilized the spine significantly compared with its intact condition, and whether the addition of supplementary translaminar screw fixation further stabilized the spine. Stabilization was defined as a reduction in motion after insertion of an implant. METHODS: Twelve lumbar functional spinal units from human cadavera were tested under pure moments of flexion, extension, bilateral axial rotation, and bilateral lateral bending to a maximum of ten newton-meters. The relative intervertebral motions were measured, with use of an optoelectronic camera system, under three test conditions: with the spine intact, after insertion of anterior interbody cages, and after insertion of anterior interbody cages supplemented with translaminar screw fixation. Six specimens were tested for each type of cage: a bilateral, porous, threaded cylinder (BAK) and a central, porous, contoured implant with end-plate fit (SynCage). RESULTS: The cages performed in a similar manner in all directions of loading, with no significant differences between the two designs. The cages significantly stabilized the spine compared with its intact condition in flexion, axial rotation, and lateral bending (the median value for motion was 40, 48, and 29 percent of the value for the intact condition, respectively; p = 0.002 for all three directions). Compared with the cages alone, translaminar screw fixation provided no additional stabilizing effect in these directions but it significantly increased the stability of the spine in extension (the median value for motion was 34 percent of the value with the cages alone; p = 0.013). CONCLUSIONS: There were no differences in the stabilization provided by the two different cage designs. Use of the cages alone stabilized the spine in all directions except extension, and use of supplementary translaminar screw fixation provided additional stabilization only in extension. CLINICAL RELEVANCE: This study demonstrated that interbody cages do not stabilize the lumbar spine in extension, and this observation was not altered by the use of substantially different designs. If the lack of stabilization in extension is a clinical problem, possible solutions include the avoidance of extension postoperatively or the use of supplementary fixation.

Biomechanical Phenomena↗

PubMedDate not supplied

Clinical study with recombinant interferon gamma versus interferon alpha-2c in patients with condylomata acuminata.

A multi-centre, randomized, open-label trial was conducted to evaluate the safety and efficacy of recombinant interferon (rIFN) alpha-2c versus rIFN gamma in patients with recurrent or persistent condylomata acuminata (CA). Thirty-three such patients were treated either with 6 micrograms rIFN alpha-2c or with 0.1 mg rIFN gamma (both equivalent to 2 x 10E6 IU), single dose, subcutaneously 3 times a week for 6 weeks. In case of no complete clearance at week 10, a second course of treatment with the other type of rIFN was given. There was no significant difference in the complete clearance proportions at week 10 between the two treatment groups (3/16 vs 6/17). No relapses occurred in these patients during the 16 weeks' follow-up. Further clearances during the follow-up resulted in a total complete clearance proportion of 14/33 at the end of study. The treatment was well tolerated. Repeated interferon therapy has its place in treating persistent or recurrent condylomas.

Adolescent↗