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Biomedical subjects

Thomas Steffen

Publications and source records attributed to Thomas Steffen.

At least 19 recordsLinked to original sources
PubMed2006

Biomechanical comparison of a unique locking plate versus a standard plate for internal fixation of proximal humerus fractures in a cadaveric model.

BACKGROUND: Newer internal fixation devices with a locking mechanism between the plate and the screw have recently been released. The efficacy of these plates in the proximal humerus has yet to be fully described. There is a need to compare the biomechanical properties of efficacy of plate fixation with or without locking screws for surgery of two-part proximal humerus fractures. Multiple-plane locking plate and cloverleaf plate designs were tested to determine their ability to maintain fixation on the humeral head. METHODS: Eight matched pairs of cadaveric shoulders with 7-millimeter osteotomy defects at the surgical neck simulating two-part fractures of the proximal humerus were loaded to failure in thirty degrees of glenohumeral abduction. One side was repaired with a proximal humerus locking plate and the other with a cloverleaf plate. The rotator cuff musculature was then loaded via a servo-hydraulic testing machine under displacement control to simulate the deforming forces present in vivo. FINDINGS: The average maximum load to failure was greater in proximal humerus locking plates than in cloverleaf plates (876 versus 712; P=0.04). INTERPRETATION: In the cadaveric, two-part proximal humerus fracture model that was created, the locking plate displayed significantly greater holding power of the humeral head. Clinical relevance is unproven but may be manifested in vivo as improved early range of motion exercises and functional outcome.

Aged↗
PubMed2006

Harvesting local cylinder autograft from adjacent vertebral body for anterior lumbar interbody fusion: surgical technique, operative feasibility and preliminary clinical results.

Autogenous iliac crest has long served as the gold standard for anterior lumbar arthrodesis although added morbidity results from the bone graft harvest. Therefore, femoral ring allograft, or cages, have been used to decrease the morbidity of iliac crest bone harvesting. More recently, an experimental study in the animal showed that harvesting local bone from the anterior vertebral body and replacing the void by a radio-opaque beta-tricalcium phosphate plug was a valid concept. However, such a concept precludes theoretically the use of posterior pedicle screw fixation. At one institution a consecutive series of 21 patients underwent single- or multiple-level circumferential lumbar fusion with anterior cages and posterior pedicle screws. All cages were filled with cancellous bone harvested from the adjacent vertebral body, and the vertebral body defect was filled with a beta-tricalcium phosphate plug. The indications for surgery were failed conservative treatment of a lumbar degenerative disc disease or spondylolisthesis. The purpose of this study, therefore, was to report on the surgical technique, operative feasibility, safety, benefits, and drawbacks of this technique with our primary clinical experience. An independent researcher reviewed all data that had been collected prospectively from the onset of the study. The average age of the patients was 39.9 (26-57) years. Bone grafts were successfully harvested from 28 vertebral bodies in all but one patient whose anterior procedure was aborted due to difficulty in freeing the left common iliac vein. This case was converted to a transforaminal interbody fusion (TLIF). There was no major vascular injury. Blood loss of the anterior procedure averaged 250 ml (50-350 ml). One tricalcium phosphate bone plug was broken during its insertion, and one endplate was broken because of wrong surgical technique, which did not affect the final outcome. One patient had a right lumbar plexopathy that was not related to this special technique. There was no retrograde ejaculation, infection or pseudoarthrosis. One patient experienced a deep venous thrombosis. At the last follow up (mean 28 months) all patients had a solid lumbar spine fusion. At the 6-month follow up, the pain as assessed on the visual analog scale (VAS) decreased from 6.9 to 4.5 (33% decrease), and the Oswestry disability index (ODI) reduced from 48.0 to 31.7 with a 34% reduction. However, at 2 years follow up there was a trend for increase in the ODI (35) and VAS (5). The data in this study suggest that harvesting a cylinder of autograft from the adjacent vertebral body is safe and efficient. Filling of the void defect with a beta-tricalcium phosphate plug does not preclude the use of posterior pedicle screw stabilization.

Adult↗
PubMed2006

Square-lashing technique in segmental spinal instrumentation: a biomechanical study.

Sublaminar wires have been used for many years for segmental spinal instrumentation in scoliosis surgery. More recently, stainless steel wires have been replaced by titanium cables. However, in rigid scoliotic curves, sublaminar wires or simple cables can either brake or pull out. The square-lashing technique was devised to avoid complications such as cable breakage or lamina cutout. The purpose of the study was therefore to test biomechanically the pull out and failure mode of simple sublaminar constructs versus the square-lashing technique. Individual vertebrae were subjected to pullout testing having one of two different constructs (single loop and square lashing) using either monofilament wire or multifilament cables. Four different methods of fixation were therefore tested: single wire construct, square-lashing wiring construct, single cable construct, and square-lashing cable construct. Ultimate failure load and failure mechanism were recorded. For the single wire the construct failed 12/16 times by wire breakage with an average ultimate failure load of 793 N. For the square-lashing wire the construct failed with pedicle fracture in 14/16, one bilateral lamina fracture, and one wire breakage. Ultimate failure load average was 1,239 N For the single cable the construct failed 12/16 times due to cable breakage (average force 1,162 N). 10/12 of these breakages were where the cable looped over the rod. For the square-lashing cable all of these constructs (16/16) failed by fracture of the pedicle with an average ultimate failure load of 1,388 N. The square-lashing construct had a higher pullout strength than the single loop and almost no cutting out from the lamina. The square-lashing technique with cables may therefore represent a new advance in segmental spinal instrumentation.

Absorptiometry, Photon↗
PubMed2006

Setting properties of four acrylic and two calcium-phosphate cements used in vertebroplasty.

STUDY DESIGN: Experimental study conducted in the laboratory with six different bone cements. OBJECTIVES: To isolate the thermal properties of conventional and emerging bone cements used in vertebroplasty and to characterize their setting behavior. SUMMARY OF BACKGROUND DATA: The heat released during setting has been linked to the desirable effects of pain relief and tumor destruction and to the undesirable effect of thermal necrosis of surrounding tissue. However, there are currently no studies that disconnect the exothermic reaction of the cements from the media in which they occur. Before the combined thermal effect is examined, it is important to understand the setting properties of cements alone. METHODS: Thirty independent experiments were conducted with four PMMA cements (Cranioplastic, Vertebroplastic, Palacos LV-40, Antibiotic Simplex) and two calcium-phosphate cements (chronOS Inject and Biopex) in accordance with ASTM standard F 451-99a. A thermocouple was placed in the center of the cement mass, and the temperature-versus-time measurements were recorded. RESULTS: The calcium-phosphate cements took over half an hour to reach their maximum temperature, which was only 3-4 degrees C higher than the ambient temperature. The temperature increase for the acrylic cements was between 16 and 23 degrees C, and it took about 15 minutes to reach the maximum temperature. The variation within the groups was also important. CONCLUSION: The exothermic reaction of calcium-phosphate cements appears to be insignificant. Although the acrylic cements release considerably greater heat in a much shorter time period, it does not appear that their temperature is sufficiently high to cause extensive thermal injury. However, variations within each group must be considered along with the intended use when deciding on the cement to be used.

Calcium Phosphates↗
PubMed2005

Internal strains in healthy and degenerated lumbar intervertebral discs.

STUDY DESIGN: A biomechanical study investigating the intradiscal mechanics of human lumbar intervertebral discs (IVDs). OBJECTIVES: To assess the relationship between nucleus pulposus migration and intradiscal strains as a function of degeneration. SUMMARY OF BACKGROUND DATA: Intradiscal deformation studies have documented the nucleus pulposus migration capabilities during bending but without assessing subsequent intradiscal strains of the anulus fibrosus. Degenerated IVDs show higher anular laxity, hypermobility, and, perhaps, segmental instability. It is unknown if nucleus pulposus migration might be the cause of increased intradiscal anular strains and if such a phenomenon is modulated by IVD degeneration. METHODS: Eighteen healthy and degenerated IVDs were subjected to compression, extension, flexion, and lateral bending. Craniocaudal radiographs at unloaded and loaded steps documented positions of wires placed within and beads glued to the external surface in the mid-transverse plane. Circumferential and radial strains from the anterior, lateral, and posterolateral regions during load were compared between healthy and degenerated IVDs. RESULTS: The nucleus pulposus migrated to the opposite side of bending regardless of bending direction and significantly more in degenerated IVDs. The highest nucleus pulposus migration was observed during lateral bending. Circumferential tensile strains were significantly higher in the posterolateral regions of degenerative IVDs during all loads. Degeneration significantly increased radial tensile and compressive strains during all bending loads. CONCLUSIONS: Increased nucleus pulposus migration in degenerated IVDs may result in increased shifting of the IVD pivot point during bending movements as well as intradiscal anular strains, particularly in the posterolateral anulus. This phenomenon may explain the segmental instability observed in degenerated segments as well as the associated anular tears present in the posterolateral region before IVD failure.

Aged↗
PubMed2005

Pull-out strength of the suprapedicle claw construct: a biomechanical study.

The pull-out of the superior screw is a well recognized problem in anterior instrumentation of the spine for scoliosis. A biomechanical pull-out study of anterior vertebral body screw in cadaveric thoracic spine was therefore designed to investigate and compare the pull-out strength of three different anterior vertebral body fixations using the AO Universal Spine System: simple bicortical screw, bicortical screw with an opposite washer (sometimes called pull-out resistant nut), and a new construct made of a bicortical screw with the addition of a suprapedicular hook on the same vertebra (or claw construct). The T4 to T9 vertebral bodies from six human cadavers (total of 36 specimens) were instrumented with three different instrumentation constructs after measuring the bone mineral density of each individual vertebra. After stabilization of the vertebral bodies, the screws were extracted employing a material testing system using axial pull-out. The maximum axial forces were recorded at the time of the construct failure. The mean ultimate fixation strength (UFS) values after being adjusted for bone mineral density and vertebral body diameter were 631, 711, and 1244 N for the three different constructs, respectively (screw alone, screw with an opposite washer, and screw with a suprapedicle claw). The difference in UFS was not significant for the first two constructs tested (screw alone and screw with an opposite washer). However, the difference in ultimate fixation strength between the claw and the other constructs was highly significant (P<0.0001). Specimens with low BMD did not benefit as much from claw construct as the ones did with a normal BMD. The failure mode of each construct was described, but was in neither case judged dangerous for the spinal cord. This study shows that the suprapedicle claw construct improves the pull-out strength of an anterior vertebral body screw by 80%, and changes the mode of failure so as not to rely only on the screw characteristics or solely on the vertebral body. By adding a suprapedicle hook in a claw configuration, one may prevent superior screw pull-out in anterior spine surgery for scoliosis.

Biomechanical Phenomena↗
PubMed2005

Clinical measurements of cement injection pressure during vertebroplasty.

STUDY DESIGN: Clinical study of injection pressure during vertebroplasty. OBJECTIVES: To investigate the range of injection pressures during conventional vertebroplasty interventions and to study the influence of syringe design and cement polymerization time on injection pressure. SUMMARY OF BACKGROUND DATA: Vertebroplasty is an efficient procedure for the treatment of painful vertebral fractures. However, cement leakage is a potentially serious complication. Although injection pressure has been suggested as a factor for extravasation risk, to date, there are only anecdotal reports of pressure data for cement augmentation in the clinic. METHODS: Using a syringe holder instrumented with load and displacement transducers, injection pressure and volume were recorded in vivo during conventional cement augmentation. Wide (3 mm opening) and normal (1.8 mm opening) syringes were alternated such that each type was evaluated for early (300-500 seconds postmixing) and late (>500 seconds postmixing) cement polymerization time. The influence of syringe type and polymerization time on injection pressure was evaluated using a multifactorial analysis of variance followed by Scheffe post hoc comparison. RESULTS: The maximum peak injection pressure measured was 3215 kPa. The average pressure peaks for normal and wide syringes were 1693 +/- 653 kPa and 1727 +/- 597 kPa, respectively. No statistically significant differences were found between injection pressures with wide and normal syringes. Higher injection pressures were observed later in the polymerization process. CONCLUSIONS: High injection pressures approaching 20 atmospheres are reached during conventional vertebroplasty. Widening the syringe tip diameter did not significantly change injection pressures, whereas elapsed time did. Further research is needed to improve injection equipment and materials for vertebroplasty.

Aged↗
PubMed2005

Atlantoaxial fusion using anterior transarticular screw fixation of C1-C2: technical innovation and biomechanical study.

This study is an attempt to describe a new technique for anterior transarticular screw fixation of the atlantoaxial joints, and to compare the stability of this construct to posterior transarticular screw fixation with and without laminar cerclage wiring. Nine human cadaveric specimens were included in this study. The C1-C2 motion segment was instrumented using either anterior transarticular screws (group 1), posterior transarticular screws alone (group 2), or posterior screws with interlaminar cerclage wires (group 3). Using an unconstrained mechanical testing machine, the specimens were tested in rotation, lateral bending, and flexion-extension using nondestructive loads of +/-2 N m. The specimens were also tested in translation using nondestructive loads of +/-100 N. All values for the three groups with regards to anterior-posterior displacement, rotation, and lateral bending were similar as determined using a Kruskal-Wallis rank sum test with a significance level of p<0.05. The only significant difference was registered in flexion-extension where the cerclage wire added some strength to the construct. Anterior transarticular screw fixation of the atlantoaxial spine has several advantages over posterior fixation techniques, and is as stable as posterior transarticular fixation in all clinically significant planes of motion. The addition of posterior interlaminar cerclage wiring further improves resistance to flexion-extension forces. Anterior transarticular screw fixation of the atlantoaxial joint is a useful technique for achieving C1-C2 stabilization.

Adult↗
PubMed2005

Effect of vertebral shell on injection pressure and intravertebral pressure in vertebroplasty.

STUDY DESIGN: An experimental biomechanical study conducted on osteoporotic cadaveric vertebrae. OBJECTIVES: 1) To measure the intravertebral shell pressure and injection pressure; and 2) to determine the effect of the vertebral shell on the intravertebral shell pressure and on the injection pressure. SUMMARY OF BACKGROUND DATA: Forces that govern cement flow are an essential component of the cement injection process in vertebroplasty. The vertebral shell may play a significant role in confining the flow of cement in the vertebral body and thereby affecting the intravertebral pressure and injection pressure. METHODS: A small fenestration was created in the left lateral vertebral shell of 14 vertebrae. A valve to open and close the fenestration and a sensor to measure the intravertebral pressure were attached to the opening. A closed fenestration simulated an intact shell, whereas an open fenestration represented a vented shell. Injection pressure and intravertebral pressure at the shell were recorded during a controlled injection. RESULTS: A closed fenestration resulted in a significant increase in the intravertebral pressure at the shell. During the injection, the shell pressure increased on average to approximately 3.54 +/- 2.91 kPa. Conversely, an open fenestration resulted in an instant relaxation of the shell pressure to the ambient pressure of 0 kPa. Additionally, the injection pressure was approximately 97 times higher than the shell pressure. CONCLUSION: The presence of vertebral shell seems to be important for intravertebral pressure. However, the intravertebral shell pressure adds very little to the injection pressure.

Biomechanical Phenomena↗
PubMed2005

Reconstructive procedure for unstable radial-sided triangular fibrocartilage complex avulsions.

PURPOSE: Radial-sided avulsions of the triangular fibrocartilage complex (TFCC) (Palmer 1D) with distal radioulnar joint (DRUJ) instability remain a challenging pathology to treat. We tested an intra-articular reconstruction that addresses unstable radial-sided TFCC avulsions. METHODS: Ten preserved, dissected, cadaveric forearm specimens with intact TFCC and without ulnar-positive variance had biomechanical testing using a hydraulic testing device. The measurement of total displacement of the ulna relative to the radius was performed with an applied load ranging from 20 N in a volar direction to 20 N in a dorsal direction. Specimens were tested sequentially with intact TFCC, with surgically induced Palmer 1D lesions, and after reconstruction of the TFCC. All tests were performed at neutral, maximal pronation, and maximal supination. RESULTS: The mean total displacements of the DRUJ of the specimens at neutral rotation were as follows: 4.1 +/- 0.4 mm for the intact specimens compared with 11.8 +/- 0.8 mm after creation of the tear and 3.9 +/- 0.7 mm for the reconstructed specimens. In maximal pronation the mean total displacements were as follows: 2.4 +/- 0.3 mm intact versus 4.9 +/- 0.7 mm for torn and 2.1 +/- 0.3 mm after reconstruction. In maximal supination the mean total displacements were as follows: 1.4 +/- 0.2 mm intact versus 5.7 +/- 1.3 mm for torn and 1.0 +/- 0.1 mm after reconstruction. All specimens obtained the preoperative pronation and supination motion after the reconstruction. CONCLUSIONS: Current procedures are unable to restore DRUJ stability without a significant limitation of pronation and supination. This intra-articular reconstruction of radial-sided TFCC avulsions succeeded in restoring baseline stability to the DRUJ without interfering with pronation/supination.

Biomechanical Phenomena↗
PubMed2004

Dosage regimes in the prescription of heroin and other narcotics to chronic opioid addicts in Switzerland--Swiss national cohort study.

AIMS: Within the guidelines of the research programme on medical prescription of narcotics for opioid addicts (PROVE), heroin, morphine, and methadone were prescribed to heavily opioid addicted individuals in Switzerland since 1994. This contribution analyses the course of dose levels during the treatment period. DESIGN: Naturalistic description of consumed dosages per day and month. SETTING AND PARTICIPANTS: The study describes the dosages prescribed to all individuals who began outpatient treatment in the PROVE programme in Switzerland between 1994 and 1996. MEASUREMENTS: Consumed amount of narcotics per day and the course of dosage of injectable heroin in different treatment regimes. FINDINGS: Heroin was the most frequently prescribed narcotic. Of all consumption days, heroin had been applied in 77% as injection and in 9% in a smokeable form. The mean daily dosage was 474 mg for intravenous application and 993 mg for the smokeable form. Second most frequent was the prescription of oral methadone, in most cases in combination with heroin. The mean amount of daily consumption of oral methadone was 53 mg. There were dosage differences between treatment regimes. During the course of treatment the mean dosage for injectable heroin per day decreased significantly and, depending on the treatment regime, almost linearly. CONCLUSIONS: The significance of heroin dosages in heroin-assisted therapy for treatment outcome should be further explored, especially in the light of the markedly higher dosages in Switzerland compared to the UK. During the treatment period, dosages did not increase but generally decreased, indicating no further increase in tolerance.

Administration, Oral↗
PubMed2003

Biomechanics of the aging spine.

The human spine is composed of highly specific tissues and structures, which together provide the extensive range of motion and considerable load carrying capacity required for the physical activities of daily life. Alterations to the form and composition of the individual structures of the spine with increasing age can increase the risk of injury and can have a profound influence on the quality of life. Cancellous bone forms the structural framework of the vertebral body. Individual trabeculae are oriented along the paths of principal forces and play a crucial role in the transfer of the predominantly compressive forces along the spine. Age-related changes to the cancellous core of the vertebra includes a loss of bone mineral density, as well as morphological changes including trabecular thinning, increased intratrabecular spacing, and loss of connectivity between trabeculae. Material and morphological changes may lead to an increased risk of vertebral fracture. The vertebral endplate serves the dual role of containing the adjacent disc and evenly distributing applied loads to the underlying cancellous bone and the cortex of the vertebra. With aging, thinning of the endplate, and loss of bone mineral density increases the risk of endplate fracture. Ossification of the endplate may have consequences for the nutritional supply and hydration of the intervertebral disc. The healthy intervertebral disc provides mobility to the spine and transfers load via hydrostatic pressurization of the hydrated nucleus pulposus. Changes to the tissue properties of the disc, including dehydration and reorganization of the nucleus and stiffening of the annulus fibrosus, markedly alter the mechanics of load transfer in the spine. There is no direct correlation between degenerative changes to the disc and to the adjacent vertebral bodies. Furthermore, advancing age is not the sole factor in the degeneration of the spine. Further study is crucial for understanding the unique biomechanical function of the aging spine.

Aged↗
PubMed2003

A synthetic peptide of link protein stimulates the biosynthesis of collagens II, IX and proteoglycan by cells of the intervertebral disc.

To date, there have been no reports on the effect on disc cells of the intervertebral disc (IVD) of the amino terminal peptide of link protein (DHLSDNYTLDHDRAIH) (link N) which is generated by the cleavage of human link protein by stromelysins 1 and 2, gelatinase A and B, and collagenase between His(16) and Ile(17). However, link N has been shown to act as a growth factor and stimulate synthesis of proteoglycans and collagen by chondrocytes of human articular cartilage. There are also no studies on the effect of link N on type IX collagen in any tissue. In the studies reported here, a serum-free pellet culture system has been used to examine whether link N can play a role in maintaining the integrity of disc matrix, specifically at the level of matrix assembly by cells of the IVD. Using this culture system, we determined the capacity of link N to stimulate accumulation of these matrix proteins in the annulus fibrosus (AF) and nucleus pulposus (NP). Gross inspection of separate AF and NP pellet cultures in the absence of link N revealed a progressive increase in size and a transition from "spherical" to "polygonal" pellets after centrifugation. Addition of 10 ng/ml link N resulted in increased pellet sizes for both AF and NP pellet cultures. Link N increased proteoglycan, type II and type IX collagen contents with an increase in DNA content over time. This study demonstrates that link N can act directly on disc cells to stimulate matrix production, which involves increased accumulation of proteoglycan, and types II and IX collagens. This study also identifies the value of pellet cultures for studies of the IVD cells in a serum-free chemically defined medium, in which pellets can continue growing in size in response to growth factors with minimal cell loss. Link N may have value in stimulating the growth and regeneration of the damaged IVD.

Amino Acid Sequence↗
PubMed2003

Effects of osteogenic protein-1 on distraction osteogenesis in rabbits.

In this study we tested the effect of locally applied osteogenic protein 1 (OP-1) on distraction osteogenesis in rabbits. Seven days after tibial osteotomy, distraction was started at a rate of 0.25 mm per 12 h for 3 weeks. At the end of the distraction period, OP-1 was injected at the site of osteotomy. Four different dosages were tested (0, 80, 800, or 2000 microg; eight rabbits per dose group). Rabbits were sacrificed 3 weeks later, and histologic, densitometric, and biomechanical parameters were assessed. No significant differences were found between groups for any parameter. To explain why this approach was only modestly successful, the expression of BMP receptor protein in the newly formed tissue was analyzed by immunohistochemistry. Strong expression of BMP receptor IA, IB, and II was found during the early distraction phase, but not during later stages of the process. Thus, it appears that the lack of receptor protein in the target tissue impairs the effect of OP-1 given at the end of the distraction period. Possibly, OP-1 could be more useful when applied early in the distraction phase.

Animals↗
PubMed2003

Elective lumbar spinal decompression in the elderly: is it a high-risk operation?

INTRODUCTION: Spinal degeneration leading to spinal stenosis is increasingly common in an aging population. Many patients are not referred for operation because of the fear of severe complications. The purpose of this study was to relate the surgical risks involved in elective spinal decompression in elderly patients to those of total hip arthroplasty, a well-accepted procedure whose risks and benefits are well known. METHODS: We reviewed the charts of 6 8 consecutive patients who underwent elective spinal decompression and fitted our inclusion criteria (65-80 yr of age, no spinal or hip operations, no hip fractures, spine fractures or cauda equina syndrome and no bone or metastatic disease). This group was matched with a similar group of 68 randomly selected patients who underwent total hip arthroplasty during the same period. We recorded the age, gender, American Society of Anesthesiologists (ASA) score, early postoperative complication rate, operative time, hospital stay and blood lost. RESULTS: The 2 groups were well matched with respect to age, gender and ASA score. The only significant intraoperative difference was operative time, with the spine procedure taking longer to complete (191 min v. 278 min). Blood loss was not significantly different. Both groups had a similar number of lift-threatening complications (12 v. 14). The number of minor complications was greater in the spinal decompression group (62 v. 125). CONCLUSIONS: Elective lumbar spinal decompression in elderly patients suffering significant pain or disability due to degenerative lumbar spinal stenosis is worthwhile. We recommend judicious use of conservative measures, but encourage referral for surgical management when these fail. This operation, even when instrumentation and bone grafting are required, is not associated with more serious or life-threatening risks than a total hip replacement in elderly patients.

Aged↗
PubMed2002

Decreasing intravenous cocaine use in opiate users treated with prescribed heroin.

OBJECTIVES: Providing maintenance treatment for heroin users who also use cocaine presents special problems. Poly-drug use is prevalent among clients in the Swiss Program for the Medical Prescription of Heroin (1994-1996). METHODS: A formative evaluation examines whether cocaine use was associated with a higher drop-out rate from treatment, and how cocaine use changed among those who remained in treatment. Frequency of cocaine use before and during treatment was measured by self-report every six months and by urinalysis every two months. RESULTS: There was no significant difference between the drop-out rates for cocaine users vs. non-users (n = 995). A significant reduction in cocaine use over an 18-month period from 84 to 48% was found for a sample of clients (n = 266). Overall retention in programme was high and also the prevalence of factors associated with cocaine use such as criminality, prostitution, and contact with drug scene decreased. CONCLUSIONS: The results suggest that prescribed heroin maintenance provides a treatment context that may help reduce consumption of other illicit drugs such as cocaine.

Cocaine-Related Disorders↗
PubMed2002

Development of a monitoring system for heroin-assisted substitution treatment in Switzerland.

OBJECTIVES: Switzerland introduced heroin-assisted treatment as a routine treatment for drug addicts. As a result the evaluation instruments were changed from a detailed scientific project to a routine monitoring system. The process for developing this monitoring system is described. METHODS: The questionnaires and assessment instruments were restyled with staff of the treatment agencies. Indicators measuring quality of treatment and measures from the future national statistic on the addiction support system were integrated into admission, course and discharge questionnaires. Currently a system for feedback to treatment agencies is being developed. RESULTS: All 21 treatment agencies are participating in the monitoring. Assessment quality is high. CONCLUSIONS: The described monitoring should provide continuous delivery of basic relevant data on patients.

Adult↗