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Biomedical subjects

M Mentzel

Publications and source records attributed to M Mentzel.

At least 19 recordsLinked to original sources
PubMed2005

[Predictive value of the HISS-scoring system for estimation of trauma severity and the time off work after hand injuries].

BACKGROUND: The estimation of the time off work depending on the injury pattern and severity is of major interest in the treatment of hand injuries. The predictive value of the HISS score (Hand Injury Severity Scoring System) was evaluated. MATERIAL AND METHODS: According to this score, 184 work-related injuries (1999 to 2002) were analyzed prospectively, excluding injuries of both hands. The median age was 37.9 years (18 to 65 years), 11 % of the patients were female. RESULTS: A significant correlation was established between the HISS score and the time off work (p < 0.0001, r = 0.51). The score also correlated with the degree of work incapacity (p < 0.0001). CONCLUSION: Our data confirm the predictive value of the HISS score for the early estimation of the time off work resulting from hand injuries. However, the estimation is limited to injuries distal to the wrist.

Accidents, Occupational↗
PubMed2003

[Treatment of flexor tendon injuries in children].

In contrast to the standard therapy of flexor tendon injuries in adults, the postoperative treatment program for children remains a controversial topic. Some prefer immobilization therapy in a variety of forms and for different periods of time. Others prefer early mobilization programs. We present results for twenty-eight children with thirty-seven flexor tendon injuries. The average age was 5.8 years. After primary tendon suture in children six years and younger (group A), our postoperative program consisted of immobilization for three weeks. The older children (group B) were treated with an early passive mobilization program. Follow-up examinations were carried out on twenty six of the children at three months and at 3.7 years. Three months after surgery, the children in group A showed only average results while those in group B presented good finger motion. After 3.7 years both groups showed good results.

Adolescent↗
PubMed2002

[Infected animal bite injuries of the extremities].

The appearance of animal bite injuries varies in regard to location and extent. Injuries with puncture wounds involving the extremities carry great risk of infection. Managing the complications often requires substantial medical treatment and increased costs. The aim of this study is the evaluation of the course of disease, medical care, and treatment costs in patients with infected bite injuries. In the year 2000, 16 patients were treated for infection after bite injuries of the extremities. Fourteen patients received substandard therapy because of incorrect assessment of the extent of the bite wound. Because of infection, the average time needed for treatment before returning to work was 3 months, including 12 days of hospitalization and 16 days of out-patient treatment. The average treatment costs exceeded 6,100 Euro for the health insurance companies. Because of its increasing prevalence and inadequate treatment, this type of injury has become a serious public health problem.

Absenteeism↗
PubMed2002

Correlation of bone mineral density with strength and microstructural parameters of cortical bone in vitro.

The aim of this study was to evaluate the influence of microstructural parameters, such as porosity and osteon dimensions, on strength. Therefore, the predictive value of bone mineral density (BMD) measured by quantitative computed tomography (QCT) for intracortical porosity and other microstructural parameters, as well as for strength of cortical bone biopsies, was investigated. Femoral cortical bone specimens from the middiaphysis of 23 patients were harvested during total hip replacement while drilling a hole (dia. 4.5 mm) for the relief of the intramedullary pressure. In vitro structural parameters assessed in histological sections as well as BMD determined by quantitative computed tomography were correlated with yield stress, and elastic modulus assessed by a compression test of the same specimens. Significant correlations were found between BMD and all mechanical parameters (elastic modulus: r = 0.69, p < 0.005; yield stress: r = 0.64, p < 0.005). Significant correlations between most structural parameters assessed by histology and yield stress were discovered. Structural parameters related to pore dimensions revealed higher correlation coefficients with yield stress (r = -0.69 for average pore diameter and r = -0.62 for fraction of porous structures, p < 0.005) than parameters related to osteons (r = 0.60 for osteon density and average osteonal area, p < 0.005), whereas elastic modulus was predicted equally well by both types of parameters. Significant correlations were found between BMD and parameters related to porous structures (r = 0.85 for porosity, 0.80 for average pore area, and r = 0.79 for average pore diameter in polynomial regression, p < 0.005). Histologically assessed porosity correlated significantly with parameters describing porous structures and haversian canal dimensions. Our results indicate a relevance of osteon density and fraction of osteonal structures for the mechanical parameters of cortical bone. We consider the measurement of BMD by quantitative computed tomography to be helpful for the estimation of bone strength as well as for the prediction of intracortical porosity and parameters related to porous structures of cortical bone.

Aged↗
PubMed2001

The total synthesis of C-glycosides with completely resolved seven-carbon backbone polyol stereochemistry: stereochemical correlations and access to L-configured and other rare carbohydrates.

The de novo synthesis of a full set of hydroxymethyl C-glycosides from only two precursors is described. The seven-carbon target molecules contain five stereocentres and bridge the stereochemical gap between natural D-configured and non-natural L-configured series of hexoses. Key steps include hydroxylation, differential protection, stereoselective reduction and desymmetrization of 8-oxabicyclo[3.2.1]oct-6-enes. C-Terminus differentiation and C-terminus excision of the seven-carbon polyol backbone lead to hexoses, including those of the L-series. A stereochemical and genetic classification of C-glycosides is presented.

Carbohydrate Conformation↗
PubMed2001

Prediction of cortical bone porosity in vitro by microcomputed tomography.

The high importance of intracortical porosity for mechanical strength of cortical bone has been established. The contribution of other parameters of microstructure such as osteon dimensions for strength is in discussion. The aim of this study was to evaluate the predictive value of microcomputed tomography (mCT) for porosity and other microstructural parameters of cortical bone in cortical bone biopsies. Femoral cortical bone specimens from the middiaphysis of 24 patients were harvested during the procedure of total hip replacement at the location where normally one hole (Ø 4.5 mm) for the relief of the intramedullary pressure is placed. In vitro intracortical porosity and bone mineral density (BMD) measurements by mCT were compared with structural parameters assessed in histological sections of the same specimens. A strong correlation was found between intracortical porosity measured by mCT and histological porosity (r = 0.95, P <0.0001). Porosity measured by mCT was also a strong predictor for other parameters describing dimensions of porous structures. BMD?1 was associated with osteonal area (r = -0.76, P <0.0001). We consider the measurement of porosity by mCT as a very potent procedure for assessing intracortical porosity and parameters related to porous structures of cortical bone nondestructively in vitro.

Aged↗
PubMed2001

[Problems of malunited fractures of the distal radius].

The essential problematic of the distal fracture of the radius lies in the quality of its reduction and retention. 35 patients with distal fractures of the radius and strain fractures of the styloid process of the ulna were followed up with regard to their functional and radiological results and their subjective symptoms. Patients with intra-articular fractures were found to have significantly poorer functional results compared to those with extra-articular fractures. 29 out of 35 patients developed a nonunion of the styloid process of the ulna in the form of a compensatory false position with a significant dorsal tilt of the articular surface of the radius. Their functional results were also significantly poorer than those of the other 6 patients. The patients whose radii were shortened by more than 2 mm also had significantly poorer functional results and a median dorsal tilt of 5 degrees of the articular surface. Where the dorsal inclination of the articular surface of the radius exceeded 5 degrees, a significant increase in the scapholunar angle, which averaged 62 degrees, was found. On the basis of these figures, we conclude that in the reduction of the distal fracture of the radius, shortening by not more than 2 mm and a dorsal inclination of the articular surface of the radius, taken laterally, of not more than 5 degrees should be tolerated in order to minimise functional impairments of the wrist.

Fractures, Malunited↗
PubMed2001

Prediction of strength of cortical bone in vitro by microcomputed tomography.

OBJECTIVE: The aim of this study was to evaluate the predictive value of bone mineral density and intracortical porosity measured by microcomputed tomography for the strength of cortical bone biopsies. DESIGN: Experimental study comparing the predictive value of bone mineral density and of intracortical porosity determined in vitro by microcomputed tomography for the mechanical properties of cortical bone cylinders. BACKGROUND: The assessment of cortical bone strength might be relevant for the prediction of fracture risk or the choice of suitable therapy strategies in orthopaedic surgery. The predictive value of cortical density for the mechanical properties is discussed controversially. The relevance of intracortical porosity measured by histomorphometry has been established, but the predictive value of porosity determined by microcomputed tomography remains to be explored. METHODS: Femoral cortical bone specimens from the mid diaphysis of 24 patients were harvested during total hip replacement procedure at the location, where a diaphyseal hole (diameter 4.5 mm) was drilled in order to reduce the intramedullary pressure. In vitro intracortical porosity and bone mineral density measurements by microcomputed tomography were compared with strength and elastic modulus assessed by a compression test transverse to the Haversian systems of the same specimens. RESULTS: Significant negative correlations were found between porosity measured by microcomputed tomography scans and yield stress, stiffness and elastic modulus (P<0.001), however, the positive correlations between bone mineral density and mechanical parameters were stronger (P<0.0001). The mechanical parameter best predicted by mineral density as well as by porosity was yield stress (r=0.72,P<0.0001;r=-0.64,P<0.001). CONCLUSIONS: Bone mineral density determined by microcomputed tomography imaging in vitro may be a potent method to predict mechanical properties of cortical bone non-destructively. The application in vivo remains to be explored.

Aged↗
PubMed2001

Predictive value of Singh index and bone mineral density measured by quantitative computed tomography in determining the local cancellous bone quality of the proximal femur.

OBJECTIVE: The purpose of this study was to assess the predictive value of the Singh index as well as quantitative computed tomography for the in vitro local mechanical competence of the cancellous bone of the proximal femur. DESIGN: An experimental study examining the relation between mechanical properties and bone mineral density of the femoral neck determined in vitro and the clinical estimated Singh index on X-rays. BACKGROUND: Evaluation of the predictive value of the Singh index, an inexpensive and simple technique for the mechanical properties of the cancellous bone of the proximal femur. METHODS: The bone quality of the proximal femur of 34 patients undergoing total hip replacement was estimated by roentgenography using the Singh index. Bone mineral density was quantified by quantitative computed tomography using cylindrical cancellous bone biopsies harvested during the total hip replacement procedure by a new biopsy method. The mechanical properties of the bone specimens (Young's modulus, strength and maximum energy absorption E(max)) were measured by mechanical testing of the bone biopsies. RESULTS: A strong correlation of the Singh index versus material properties of cancellous bone was noted (r=0.66 for Young's modulus, r=0.73 for strength and r=0.69 for E(max), P<0.0001). The correlations of bone mineral density measured by quantitative computed tomography versus Young's modulus, strength and energy absorption E(max) were significant. Strength was predicted best (r=0.82; P<0.0001), followed by E(max) (r=0.79; P<0.0001) and Young's Modulus (r=0.73; P<0.0001). CONCLUSIONS: We conclude, that assessment of bone mineral density by quantitative computed tomography is a reliable and precise method for the estimation of cancellous bone material properties. The Singh index provides a rough estimate for the mechanical competence of the proximal femur. It is inexpensive, simply to assess and can in some cases replace the measurement of bone mineral density, notably in cases of marked decrease in bone density.

Aged↗
PubMed2001

Predictive value of bone mineral density and morphology determined by peripheral quantitative computed tomography for cancellous bone strength of the proximal femur.

Peripheral quantitative computed tomography (pQCT) is an established diagnostic method for assessment of bone mineral density in the diagnosis of osteoporosis. However, the capacity of structural parameters of cancellous bone measured by high-resolution computed tomography remains to be explored. In 33 patients, bone mineral density (BMD) of the proximal femur was measured in vitro by pQCT using cylindrical biopsies from the intertrochanteric region harvested before the implantation of an artificial hip joint. By digital image analysis of CT scans, parameters derived from histomorphometry describing the microarchitecture of cancellous bone were measured. The biopsies were also loaded to failure by an uniaxial compression test to determine the biomechanical parameters, Young's modulus, strength, and maximum energy absorption (E(max)). Strong correlations were found for BMD vs. mechanical parameters (r = 0.73 for Young's modulus, r = 0.82 for strength, and r = 0.79 for E(max); p < 0.001, n = 29). The morphological parameters, bone volume per trabecular volume (BV/TV), apparent trabecular thickness (app.Tb.Th), apparent trabecular separation (app.Tb.Sp), and trabecular number (Tb.N), correlated significantly with all mechanical parameters. The combination of morphological parameters with BMD in a multivariate regression model led to an overall, but only moderate, increase in R(2) in all cases. Our data confirm the high predictive value of BMD for the mechanical competence of cancellous bone of the intertrochanteric region. However, quantification of cancellous bone structure by image analysis of CT scans may provide additional qualitative information for the analysis of bone strength.

Aged↗
PubMed2001

Functional treatment of physeal and periphyseal injuries of the metacarpal and proximal phalangeal bones.

BACKGROUND/PURPOSE: Hand fractures are common injuries in infants. Complications are rare because of potent remodeling dimension and rapid healing of growing bone. There is limited remodeling capacity for angular and rotational deformity so displaced fractures often require open reduction and internal fixation. METHODS: The authors present a splint system for a protected reduction and mobilization program of displaced proximal phalanx and metacarpal fractures. The custom-molded 2-component thermoplastic splint allows motion of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints. It has been developed to allow bone healing and recovery of motion at the same time. In this study, the authors evaluated the clinical and radiologic results of a series of 11 consecutive infants with displaced metacarpal fractures and 13 displaced proximal phalanx fractures who received functional treatment. RESULTS: Fracture consolidation and full active motion was achieved simultaneously in 4 weeks in 21 children; 2 infants required physiotherapy, and 1 child was lost to follow-up. No further growth abnormality was seen within a 12-month observation period. CONCLUSION: When there is no damage of soft tissue the functional mobilization program can lead to good results treating displaced physeal and periphyseal hand injuries of proximal phalanx and metacarpal fractures. J Pediatr Surg 36:611-615.

Child↗
PubMed2001

[Reproducibility of measuring the finger joint angle with a sensory glove].

Joint angles are measured using goniometers according to the neutral-zero method. These measurements are dependent on the examiner and are thus subject to great variation. With a newly developed sensor glove, the grip patterns of the hand can be captured with a computer-assisted technique. In a comparative study involving five subjects, the joint angles during power grip around a cylindrical body and while clenching a fist were determined by nine examiners at three different times, using the conventional technique according to the neutral-zero method. In the same experimental design, the joint angles were measured with the sensor glove. As a criterion for the reproducibility of the measurements, the intraclass correlation coefficient (ICC) was calculated by means of an analysis of variance. The ICC is a value which approximates 1 if the reliability of the measurements is high. At 0.94, the ICC of the data determined with the sensor glove was markedly higher than the mean ICC for all examiners of 0.50 using the conventional method. Besides the measurement of the finger joint angles, the sensor glove allows the dynamic recording of joint movements of all finger joints during different grip patterns of the hand.

Adult↗
PubMed2001

[Measuring grip strength of the hand with a sensor glove by gripping with submaximal and maximal strength].

Grip strength measurements with the aid of dynamometers are dependent on the cooperation and motivation of the individual examined. Recognising a simulated loss of grip is a hitherto unresolved problem. With a sensor glove developed at the Berlin University of Technology, the force distribution pattern of any form of grip can be captured via ten pressure sensors and evaluated by computer. In five subjects, the force distribution patterns at submaximum and maximum force of five different grips were determined in three successive measurements each. The data were recorded in force-time diagrams. For each act of grasping, the measurements produced a curve with near-constant measuring signals within a defined period (plateau). The difference in the plateau heights of successive grips and the structures of the individual plateaux (oscillation, standard deviation) were used as distinguishing criteria. The dynamics of the measuring signals showed statistically significant differences between grips with submaximum and maximum force (p < 0.0001).

Adult↗
PubMed2001

[Results of basal joint arthrosis treatment--comparison of Epping ligament reconstruction with trapeziectomy alone].

Objective of this study is to compare clinical and radiological results of two different methods of treatment for trapeziometacarpal osteoarthrosis of the thumb. Eighteen patients received operative treatment. An operation according to Epping was performed in eleven cases (collective I), while nine cases were treated with a trapeziectomy only (collective II). The mean follow-up of the first collective was 40 months and 15 months for the second one. The results of the two patient groups were subjected to statistical comparison in a retrospective study. This revealed no significant differences with regard to active range of motion, power, and subjective symptoms, classified according to the Buck-Gramcko score. With a mean of 49 points for the first and 50 points for the second collective, both achieved very good results. However, the mean operating time was significantly shorter in the patients treated with a trapeziectomy only, while the mean distance between the base of the first metacarpal bone and the scaphoid bone was significantly greater in this group. This is surely due to the shorter follow-up of the patients who underwent trapeziectomy only, since further proximalisation has to be expected. We were able to demonstrate that both methods yield equally good results, and hence the simpler technique of trapeziectomy alone should be given preference, at least in the standard situation of a patient, whose intermetacarpal ligaments offer sufficient stability after trapeziectomy.

Carpal Bones↗
PubMed2001

[Dorsal V-ligament reconstruction in scapholunate instability].

In dynamic and static scapholunate instability after trauma, the repair of the scapholunate ligament is important to avoid scapholunate advanced collapse of the wrist. Direct suture even of fresh-torn ligaments can be technically demanding and occasionally unreliable, thus reconstruction may require additional tissue beside the ligament. Eighteen patients suffering from dynamic (n = 10) and static (n = 8) scapholunate instability were treated by a dorsal ligament reconstruction six months after trauma. A clinical wrist score according to Cooney showed an average of 86 points (maximum 100) within a follow-up of nineteen months after surgery. X-ray films documented no significant loss of scapholunate reduction. Using local tissue only, this method is always possible, very reliable and easy to perform.

Adolescent↗
PubMed2000

[Conservative management of articular metacarpophalangeal joint fractures].

We present a splint system for a protected mobilization program after closed reduction of articular proximal phalangeal base fractures. This therapy consists of the periarticular soft tissue and functional anatomy. The soft-tissue around the base of the proximal phalanx leads to a circular stabilization effect. This so called Zancolli Complex (Metacarpophalangeal Retention Apparatus) can be used with the effect of a brace treatment. Treating 31 patients with articular fractures of the proximal phalanx way we found good functional results within a mean follow up period of 2 years after the accident.

Adult↗
PubMed2000

[Soft tissue reconstruction after scalping injury caused by a dog bite].

The reconstruction of soft-tissue damage on the part of the head which is covered with hair is aimed not only at repairing the damage in such a way that it will withstand mechanical strain but also at the restoring the hair on the scalp. In a 5-year-old boy with a scalping injury involving second- and third-degree soft-tissue damage over an area of 20 x 12 cm after a dog bite, surgery was initially performed to transform the damage into purely second-degree damage, which was then repaired with a split skin graft. One year later, the scalp containing the hair was stretched with the aid of two skin expanders over a period of 3 months, so that the split skin graft area could be removed and the hair on the scalp restored.

Animals↗