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Biomedical subjects

F F Hennig

Publications and source records attributed to F F Hennig.

At least 19 recordsLinked to original sources
PubMed2007

Longitudinal in vivo reproducibility of cartilage volume and surface in osteoarthritis of the knee.

OBJECTIVE: The aim of this study was to evaluate the longitudinal reproducibility of cartilage volume and surface area measurements in moderate osteoarthritis (OA) of the knee. MATERIALS AND METHODS: We analysed 5 MRI (GE 1.5T, sagittal 3D SPGR) data sets of patients with osteoarthritis (OA) of the knee (Kellgren Lawrence grade I-II). Two scans were performed: one baseline scan and one follow-up scan 3 months later (96 +/- 10 days). For segmentation, 3D Slicer 2.5 software was used. Two segmentations were performed by two readers independently who were blinded to the scan dates. Tibial and femoral cartilage volume and surface were determined. Longitudinal and cross-sectional precision errors were calculated using the standard deviation (SD) and coefficient of variation (CV%=100x[SD/mean]) from the repeated measurements in each patient. The in vivo reproducibility was then calculated as the root mean square of these individual reproducibility errors. RESULTS: The cross-sectional root mean squared coefficient of variation (RMSE-CV) was 1.2, 2.2 and 2.4% for surface area measurements (femur, medial and lateral tibia respectively) and 1.4, 1.8 and 1.3% for the corresponding cartilage volumes. Longitudinal RMSE-CV was 3.3, 3.1 and 3.7% for the surface area measurements (femur, medial and lateral tibia respectively) and 2.3, 3.3 and 2.4% for femur, medial and lateral tibia cartilage volumes. CONCLUSION: The longitudinal in vivo reproducibility of cartilage surface and volume measurements in the knee using this segmentation method is excellent. To the best of our knowledge we measured, for the first time, the longitudinal reproducibility of cartilage volume and surface area in participants with mild to moderate OA.

Adult↗
PubMed2006

Evaluation of low-cost computer monitors for the detection of cervical spine injuries in the emergency room: an observer confidence-based study.

BACKGROUND: To compare the diagnostic value of low-cost computer monitors and a Picture Archiving and Communication System (PACS) workstation for the evaluation of cervical spine fractures in the emergency room. METHODS: Two groups of readers blinded to the diagnoses (2 radiologists and 3 orthopaedic surgeons) independently assessed-digital radiographs of the cervical spine (anterior-posterior, oblique and trans-oral-dens views). The radiographs of 57 patients who arrived consecutively to the emergency room in 2004 with clinical suspicion of a cervical spine injury were evaluated. The diagnostic values of these radiographs were scored on a 3-point scale (1 = diagnosis not possible/bad image quality, 2 = diagnosis uncertain, 3 = clear diagnosis of fracture or no fracture) on a PACS workstation and on two different liquid crystal display (LCD) personal computer monitors. The images were randomised to avoid memory effects. We used logistic mixed-effects models to determine the possible effects of monitor type on the evaluation of x ray images. To determine the overall effects of monitor type, this variable was used as a fixed effect, and the image number and reader group (radiologist or orthopaedic surgeon) were used as random effects on display quality. Group-specific effects were examined, with the reader group and additional fixed effects as terms. A significance level of 0.05 was established for assessing the contribution of each fixed effect to the model. RESULTS: Overall, the diagnostic score did not differ significantly between standard personal computer monitors and the PACS workstation (both p values were 0.78). CONCLUSION: Low-cost LCD personal computer monitors may be useful in establishing a diagnosis of cervical spine fractures in the emergency room.

Attitude of Health Personnel↗
PubMed2005

Bone-implant interface shear modulus and ultimate stress in a transcortical rabbit model of open-pore Ti6Al4V implants.

This experimental study on laser-textured implants aimed to evaluate periimplant bone elasticity and ultimate stress of the bone-implant interface in a rabbit femur model. After randomization, two cylindrical Ti6Al4V samples (3.5 mm wide, 5.5 mm long) were transcortically implanted in each femur of 15 female New Zealand White Rabbits. Polished implants had been laser-textured with 100, 200, and 300 microm diameter pores, and another corundum blasted implant was additionally textured with 200 microm pores. Twelve weeks into the experiment, a modified push-out test was performed. The median shear modulus indicating the elasticity of the periimplant bone was 41.12 MPa for the proximal implant location and 25.38 MPa for the distal, without evidence for significant differences between implant types. Taking into account the median ultimate shear stress for 200 microm implants with and without corundum blasting, no significant difference could be demonstrated. However, for blasted 200 microm implants a statistically significant (p<0.025) relative gain in ultimate shear stress of 41% and 17% was proven in comparison with 100 and 300 microm implants, respectively. Non-blasted 200 microm implants reached 48% relative gain in respect of 100 microm samples.

Alloys↗
PubMed2005

[Generalized compartment syndrome after excessive drinking. A rare complication of psychological disorders?].

Psychogenic polydipsia can lead to compartment syndromes, which is too infrequently considered in psychiatric patients who binge-drink on hypotonic fluids. If masked by the leading clinical presentation of cerebral edema, compartment syndromes of the extremities may be diagnosed too late or remain undetected. Based on a literature review and case report, we discuss additional factors and the specific features of diagnosis and treatment.

Adult↗
PubMed2004

[The biofeedback sole tested is a suitable device for avoiding overload under partial load].

During healing of fractures and after implantation of artificial joints mobilization with partial load is a widespread and well-accepted therapeutic principle. Translating our recommendations into action, however, overtaxes many of the patients. The use of the biofeedback sole tested should guarantee avoiding overload under partial weight-bearing conditions. The distribution of the strain sensors in the biofeedback sole was primarily checked with the help of an established system controlling the distribution of strain (PAROTEC) in 17 voluntary, healthy people. Afterwards the biofeedback sole was connected to a digital recording system to analyze the number of steps overloaded in different test cycles in 50 volunteers while using crutches and performing partial load with 20 kg. The distribution of the strain sensors in the biofeedback sole is correct to control partial load under weight bearing with 20 kg. The permanent use of the biofeedback sole showed highly significant advantages in avoiding overload. The number of steps overloaded was reduced by 77%. This effect is independent from body weight or age.

Adult↗
PubMed2003

Treatment of posterior epiphyseal disruption of the medial clavicle with a modified Balser plate.

BACKGROUND: Acute posterior dislocation of the sternoclavicular joint is a rare but dangerous injury that is often difficult to diagnose. Because of late closure of the medial clavicular epiphysis, epiphyseal disruption must be taken into consideration in patients up to 25 years of age with an apparent diagnosis of posterior sternoclavicular dislocation. We developed a novel method of treating epiphyseal disruptions with a modified Balser plate. METHODS: This method was used in a 19-year-old patient with a posterior epiphyseal disruption of the left medial clavicle. After molding of the plate, the hook was introduced into the manubrium sterni and the plate was fixed on the clavicle with screws. RESULTS: The new method could be applied safely and achieved a good functional result without any external immobilization. The postoperative course was uneventful. CONCLUSION: Fixation of the posterior epiphyseal disruption of the medial clavicle with a modified Balser plate is feasible and may be an alternative to traditional methods.

Adult↗
PubMed2002

An expandable nailing system for the management of pathological humerus fractures.

BACKGROUND: People with metastatic fracture of the humerus are of poor general health. Often they are not able to compensate the handicap of an impaired extremity. Standard osteosynthetic techniques are not always applicable. To reduce the trauma of the operation, we used the Fixion expandable nail system. METHODS: At two centers, 23 metastatic fractures of the humerus (in 22 patients) were stabilized with a new nailing system. The nail expands under hydraulic pressure up to 150% of its uninflated diameter, gaining long frictional contact to the bone. All patients were followed up until osseous healing occurred or until they died. RESULTS AND CONCLUSIONS: The operative time was approximately 32 min, including 1.4 min fluoroscopy time. Nail insertion is brief and therefore not very stressful to the group of debilitated patients who require this intervention. Immediately postoperatively, the upper extremity is stable to permit physiotherapy. In these few patients, we saw no complications. The advantages of the surgical approach appear to outweigh those of conservative management options if a simple and safe surgical technique makes the humerus stable enough to resist normal daily loads.

Aged↗
PubMed1999

Comparison of 3,000 IU aXa of the low molecular weight heparin certoparin with 5,000 IU aXa in prevention of deep vein thrombosis after total hip replacement. German Thrombosis Study Group.

BACKGROUND: The aim of this randomized, double-blind and prospective clinical trial was to investigate whether an increase of the conventional daily dosage (3,000 IU aXa) of the low molecular weight heparin certoparin up to 5,000 IU aXa/day might lower the incidence of deep vein thrombosis (DVT) in patients undergoing elective hip surgery. METHODS: The main criterium of this trial was the incidence of DVT diagnosed by bilateral ascending venography, which was performed either if DVT was clinically suspected or in each remaining patient between the 12th and the 14th postoperative day. A total number of 172 patients were enrolled to receive the conventional dosage of 3,000 IU aXa (Mono-Embolex NM) and 169 patients to receive the high dosage form (5,000 IU aXa) once daily. The mean age (+/-SD) was 69.6+/-9.5 and 67+/-11.7 years. RESULTS: No relevant differences were found concerning predisposing risk factors. The duration of surgery was 93+/-25.2 and 88+/-21.4 min (mean+/-SD). Surgical type and approach were not different between the groups. Deep vein thrombosis was detected in 17 patients (9.9%) in the conventional dose group and in 16 patients (9.5%) in the high dose group (intent-to-treat analysis; n.s.). The rate of bleeding complications was not significantly different except the cell saver volumes (770+/-136 vs 475+/-186 ml; p<0.001). No significant difference was found in the serious adverse event reporting along the lines of EC-GCP (10 vs 8 events; p=0.65). CONCLUSIONS: This clinical trial confirmed that the conventional dosage (3,000 IU aXa/day) of certoparin ensures maximal antithrombotic activity.

Adult↗
PubMed1996

[Quality of life after survival of severe trauma].

Quality of life (QoL) was analyzed in 73 patients with severe multiple trauma (PTS > or = 40 patients) between 1 and 13 years after injury. QoL was assessed by the Aachen Longtime Outcome Score (ALOS), the Spitzer Index (SI) and individual self-assessment. The patients were asked about further social, financial, psychological and physical items. According to the ALOS, 81% of the patients showed moderate, 14% severe and 5% no disability. In 66% of the patients a favorable Spitzerindex (8-10 points) was found. Only 14% had poor SI scores (0-4 points). Also, two out of three patients regarded the current state of their health as "good" or "very good". Predominantly, handicaps resulted from permanent physical disability, in particular the lower extremities, whereas psychosocial and financial problems were reported infrequently. Besides injuries to the head or extremities, low QoL correlated with severity of injury and increasing age. Within the first 4 post-traumatic years SI and ALOS, as well as individual self-assessment, improved with time after injury. The rate of patients who returned to work (69%) was similar to other multiple trauma series, including series with less severe injuries. The reasonable long-term outcome even after severe multiple trauma seems to justify the enormous staff and economic expense required to manage these patients. Further improvement in QoL may be achieved by professional psychological support and early fracture treatment.

Adaptation, Psychological↗
PubMed1996

[Possibilities for early ambulation and long-term outcome of treatment of trochanteric fractures with the dynamic hip screw and gamma nail].

We studied early mobilisation and long-term results in patients treated with the dynamic hip screw (DHS) or gamma nail after trochanteric fractures. Both implants showed good results in stable fractures; patients with unstable fractures were able to walk with full load earlier when treated with the gamma nail. We recommend the DHS for stable and the gamma nail for unstable trochanteric fractures.

Aged↗
PubMed1995

[Reactivity of cortical bone capillaries. Functional TEM analysis with adrenaline, ATP and insulin].

In order to study any morphological effects that vasoactive drugs might exert on cortical bone capillaries, Swiss mice received one intravenous bolus injection each of epinephrine, ATP and insulin. In one control group saline solution was injected and another was not treated. All animals were handled in the same way. A piece of the tibia diaphysis was resected and prepared for transmission electron microscopy (TEM). The lumina and the endothelia of capillaries were submitted to computerized morphometry. Some significant changes were noted: epinephrine increases both the width of the lumen and the endothelium. ATP decreases the endothelium. Insulin (hypoglycaemia?) thickens the endothelium. These finding suggest some physiological hypotheses: the epinephrine-induced widening of the lumen and the thickening of the endothelium might reflect a decreased extravasal space and oedema of cortical bone that might cause the diffusion of minerals to take longer. Intracortical perfusion pressure would then decrease and the bone perfusion rate increase. ATP might reduce the transcapillary diffusion time and increase the extravasal space in cortical bone. Apparently there are specific insulin receptors in cortical bone capillaries.

Adenosine Triphosphate↗
PubMed1995

[Abrasion reducing polyethylene ceramic-metal compound hip prosthesis head].

There are two specific problems in using metallic or ceramic heads for hip prostheses: (1) the amount of polyethylene abrasions in the cup caused by the heads (especially a metal head). (2) the polyethylene abrasions caused by Al2O3 ceramic heads is far less than metal heads, but its ability to adapt geometrically is limited due to its being less strong. The abrasions appear because of geometric differences in the prosthetic joint, local problems in the surface architecture and physical/chemical interactions between the different materials. In this study we compare the new "Titan-Niob Ceramic Multilayer Sandwich Head" (built three layers of microsegregation phases and three in-between layers of ultrathin metal, 8-10 microns thick, and a surface with integrated grease holes) with the common CoCrMo heads and Al2O3 ceramic heads. Testing 2,000,000 cycles in a bodylike liquid under permanent loads of 90 kPa, periodically increasing up to 250 kPa, simulating normal stress situations (i.e., walking), the "Titan-Niob Ceramic Multilayer Sandwich Head" showed major advantages over the metal heads and also over the ceramic heads even though the ceramic head has been accepted so far to have the best friction coefficient. Furthermore, there has been no problem in surface fracture with the "Titan-Niob Ceramic Multilayer Sandwich Head".

Biomechanical Phenomena↗
PubMed1994

[Hip dislocation without fracture--a trauma surgery emergency].

Between 1968 and 1990, 26 patients (medium age 24.2 years) with a traumatic hip dislocation without fracture were treated at the Dept. of Trauma Surgery of the University Erlangen-Nuremberg. Only 26.9% of the patients had no further injuries beside the hip dislocation. An early closed reduction was carried out whenever possible. In 96.0% of the cases, radiological acceptable results have been achieved with the closed reduction. In 4.0% an open reduction became necessary. After a period of three to four weeks of extension, the patients had been mobilized to nonweight bearing status. Stress on the injured leg was increased progressively, that full weight bearing capacity was achieved after three months. It was possible to examine 12 of the 26 patients. Good and very good results based on the Merle d'Aubigné score and on the Thompson and Epstein score were obtained in 11 of the 12 patients. The complication seen most often was posttraumatic coxarthritis of the hip. We have not seen any necroses of the head of femur in our patients to date. All our results indicate, that the immediate and careful reposition under anaesthesia seems to be the most important factor in preventing a necrosis of the head of femur.

Adolescent↗
PubMed1992

Nickel-, chrom- and cobalt-concentrations in human tissue and body fluids of hip prosthesis patients.

The world-wide experience with millions of metallic implantations suggests the biocompatibility of modern alloys, commonly made of cobalt, chromium and nickel. There is, however, little information available on the internal metal exposure resulting from implants. In this study we assessed the metal concentrations in body fluids and tissue samples (muscle, bone) of patients who had undergone total hip replacement. Our patients were divided up into two groups. One group had firmly fixed implants two years after surgery. The other group had loose implants of the same Co-Cr-Mo alloy. Urine analyses revealed an increased renal elimination of nickel, chromium and cobalt. Cobalt and nickel exceeded the upper normal value. In serum the concentrations of nickel and chromium were normal or slightly elevated, the cobalt concentrations were significantly elevated. In some cases tissues adjacent to the implant showed extremely high concentrations of chromium and cobalt. This finding was also obtained in tissues that had no direct contact with the arthroplasty. The findings suggest that alloys of prostheses can undergo corrosion and release metal ions.

Aged↗
PubMed1992

[A comparative study of the characteristics of femoral hip prosthesis heads--study and results ceramic-coated hip joint heads of titanium].

Today, only hard/soft cup and femoral head combinations are employed for hip joint prostheses. Highly polished ceramic is a material with very good tribological properties for femoral heads, being highly resistant to mechanical wear and tear, and highly resistant to chemical reactions in the biological environment. The advantage of metal heads, in contrast, undoubtedly lies in their resistance to breakage and the ease with which their geometry can be modified with respect, for example, to antirotation angle and neck length. The ideal material for femoral heads is a combination of the two materials. The new multi-layer combination of titanium-niobium oxide/nitride ceramic coating applied to a prehardened titanium head combines the positive material properties in an ideal manner. Femoral heads made of CoCrMo, oxide-hardened titanium, aluminium oxide or multilayer titanium-niobium ceramic were compared by means of friction an wear and tear tests. The TiNb-ceramic-metal heads showed similar abrasion at the surface as the ceramic heads. At the high loads of more than 400 kp, which may also be reached under physiological conditions, the specially coated titanium-ceramic heads proved to be superior in terms of resistance to fracture and tribological properties.

Biomechanical Phenomena↗