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Biomedical subjects

H P Hofer

Publications and source records attributed to H P Hofer.

At least 19 recordsLinked to original sources
PubMed2001

Observations concerning different patterns of bone healing using the Point Contact Fixator (PC-Fix) as a new technique for fracture fixation.

The recent trend in all surgical disciplines has been the development of techniques in minimally invasive surgery and the optimal maintenance of the blood supply to the bone fragments during osteosynthesis. Currently, the Point Contact Fixator (PC-Fix) has been introduced as a new implant for the stabilization of forearm bones. This plate-like splint and screw fixation system, which actually acts as an internal fixator, is characterized by minimized isolated contacts to the bone and proven angular stability of the monocortically locked screws. By using the PC-Fix, a further reduction of damage to the blood supply to the bone is achieved. Since 1994, 38 patients have been treated with this new device; we have reviewed the radiographs of 52 consolidated forearm fractures/osteotomies in accordance with the patterns of bone healing associated with the different methods of implant application according to the fracture type. In the groups in which traditionally precise reduction, interfragmentary compression and stable fixation was achieved (N=31), we found in 71% an absence of periosteal callus (direct bone healing). In the groups in which compression and adaptation were combined, or even main fragments adapted without compression, with wedges remaining unreduced in soft tissue connection (N=21), we found a visible external callus in 81% (indirect healing) (P = 0.002). Indirect healing after internal fixation is no longer regarded as a disturbance to healing, but is a goal in itself. The appearance of callus is a welcome sign indicating a prompt and positive reaction in the course of bone union which will lead to progressive fracture immobilization. When using the PC-Fix in a "biological way", callus formation and solid union take place earlier than in conventional plating. The new internal fixator offers substantial technical and mechanical advantages in fracture treatment. Therefore, it is an ideal implant to satisfy the requirements of modern biological osteosynthesis without compromising the restoration of axial alignment, rotation, length and postoperative functional treatment.

Adolescent↗
PubMed2001

Blood polymorphonuclear leukocyte activation in atherosclerosis: effects of aspirin.

The aim of the study was to demonstrate an activation of polymorpho-nuclear leukocytes (PMNs) in chronic progressive atherosclerosis (ATH). A group of patients with ATH, and a group of ATH patients under aspirin (ASA) therapy were compared with control persons without atherosclerotic alterations (healthy controls). Each group comprised 15 male age-matched subjects. The following inflammatory parameters related to PMN activities were measured: the polymorphonuclear leukocyte (PMN) blood count; blood PMN migration and reactive oxygen species release in vitro; the blood levels of PMN elastase, malondialdehyde, antibodies to oxidized LDL and soluble ICAM-1. In ATH patients, the PMN blood counts and the share of blood PMNs migrating upon platelet activating factor and leukotriene B4 stimulation were significnatly above the values of the healthy controls, while the other parameters were not significantly altered. ASA treatment attenuated the inflammatory response and reduced the differences between ATH and the healthy controls. It can be concluded that, in patients with chronic progressive atherosclerosis, PMNs are involved in the inflammatory process underlying the disease.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Unstable fractures of the upper thoracic spine.

Unstable fractures of the upper thoracic spine are a therapeutic challenge because of the high rate of associated injuries and frequent occurrence of spinal cord lesions. This study focuses on the operative treatment of these injuries. We present nine patients with unstable injuries of the upper thoracic spine. According to the classification of Magerl et al., there are seven type C and two type B fractures. Eight patients had complete transverse lesions of the cord and one had no evidence of spinal cord injury. All patients presented associated injuries: nine patients had fractured ribs, three a fractured sternum and three a severe haemothorax. All underwent operative treatment: six posterior fusions only, two anterior interbody fusions only after thoractotomy owing to severe bleeding from ruptured intercostal arteries, and one a combined fusion after failure of posterior fusion. The treatment of these patients should be individualized, depending on the associated injuries, loss of blood owing to fractured spine and ruptured vessels and depending on the back pain resulting from an unstable thorax. In general, we prefer the posterior approach to unstable fractures of the upper thoracic spine.

Adolescent↗
PubMed1997

[First experiences with unreamed AO intramedullary nail in treatment of femoral shaft fractures].

The unreamed femoral nail (UFN) system, with its numerous proximal interlocking options, allows a minimal invasive surgical procedure for the treatment of nearly all femoral fracture patterns. Sixty-six fractures, 5 cases of osteolysis or pathologic fractures, 2 limb shortenings and 1 lengthening (monorail technique) and 3 cases of pseudarthrosis were stabilised with the UFN from July 1994 to December 1996. The fractures were analysed according to the AO classification. We found 31 polytrauma patients with an mean ISS of 21.8 and a mean PTS of 25.4. Most of the multiply injured patients (n = 26) were stabilised with the UFN primarily. Follow-up of 44 patients ranged from 4 to 18 months postoperatively. According to our clinical and radiological score the results were excellent in 34% of cases, good in 36.3%, poor in 20.4% and bad in 9%. Average fracture healing time was about 9.8 weeks.

Adolescent↗
PubMed1997

Influence of age on the release of reactive oxygen species by phagocytes as measured by a whole blood chemiluminescence assay.

Polymorphonuclear and mononuclear phagocytes play an important role in host defense, but may also cause tissue injury through excessive inflammation. Reactive oxygen species (ROS) are not only directly ore indirectly involved in a wide variety of clinical disorders, such as atherosclerosis, reperfusion injury, pulmonary toxicity and cancer, but they are also important in the aging process. This process is associated with increasing susceptibility to infection. In this study we investigated the influence of age and sex on phagocyte activation by means of a whole blood chemiluminescence (CL) assay. Circulating phagocyte activity was measured in 55 healthy volunteers (24 females, 31 males) aged from 6 to 92 years. Using an automated luminescence system, phagocytes were stimulated by polystyrene beads and Luminol-enhanced CL was determined in terms of peak height and peak time in freshly withdrawn, peripheral venous whole blood. An extremely significant positive correlation (p < 0.0001) between the maximum of light emission after stimulation and increasing age was found. This finding is true for the total population of blood phagocytes as well as for a single cell. In contrast the time of the appearance of the maximum of light emission showed an extremely significant inverse correlation (p < 0.0003) with increasing age. The influence of sex on the CL-parameters showed no significant difference between women and men. It is concluded that the increased susceptibility of circulating phagocytes to oxidative burst in elderly subjects may be the consequence of several biological events. Senescent cells express more and also have new antigens on their surfaces that trigger an autoimmune response. Cellular senescence appears earlier in old organisms. Therefore phagocytes in aging individuals may be increasingly involved in their scavenger tasks that grow with the catabolic bias in cell turnover. Moreover, atherosclerotic alterations in the intima and endothelial lesions are physiologic concomitants of age and may lead to a stimulation of circulating phagocytes.

Adolescent↗
PubMed1996

The influence of trauma on changes in neutrophil granulocyte function assessed by an analysis of granulocyte migration.

We examined the effects of trauma on polymorphonuclear leucocyte (PMN) migratory parameters and PMN elastase release, with the aim of tracing an acute inflammatory reaction from its very beginning to the phase of recovery. Fifteen patients who underwent monotrauma surgery, followed by uneventful healing, served as inflammation model. PMN activation was studied by measuring their readiness to migrate (TMI) and their penetration potency (DC) in a whole blood membrane filter device, in which a chemoattractant depot (FMLP) was integrated. Control chambers lacking FMLP provided parameters of the spontaneous migration. In healthy controls (n = 64), the numbers of invading PMNs decreased continuously from the outermost layer towards the interior of the filter device. FMLP did not influence the mobilization rate of PMNs immigrant from the blood into the filter, but those cells that did migrate penetrated deeper (P < 0.05). After trauma, the spontaneous and FMLP-stimulated DC was increased (P < 0.05). Trauma also tended to inhibit PMN migratory activity episodically; depression of the unspecific immune function (low TMI values) was found on the 3rd (P < 0.0001) and 12th (P < 0.01) postsurgical days. There was no correlation between the migratory parameters and the inflammation parameter, PMN elastase release. Preliminary results indicate that analyses of PMN migratory parameters by a whole blood membrane filter assay could provide a valuable adjunct in monitoring trauma-associated immunologic changes.

Acute-Phase Reaction↗
PubMed1996

[Indications and use of "AO pinless fixateurs". A preliminary report].

Improvements in techniques for the management of open tibial fractures with the external fixator have made a great impact on the final results in recent years. More recently this system has been discussed controversially. The longer treatment takes, the more likely it is that complications will occur when relying solely on the conventional external fixator. The new pinless fixator for the tibia was designed to overcome these problems. Early conversion to a more stable implant is one of the primary goals of this system. In this article the pros and cons are presented in detail and the limitation of this device explained. Moreover first clinical experiences are summarized and possible additional indications highlighted.

Equipment Design↗
PubMed1995

[Hyperextension injury of the lower cervical spine and diagnosis of dorsal unstable motion segments].

Five patients with hyperextension injuries and dorsally instable motion segments are presented. In the diagnosis of posterior instabilities plain roentgenograms demonstrated no characteristic signs of an injured cervical spine. Flexion and extension views detected a mild degree (2 mm) of retrospondylolisthesis in four cases and a widened disc space in one case. In all five patients the MR findings that made use suspect a posterior unstable motion segment were disc protrusions; in addition, in two patients these was hemorrhage in the spinal cord and in one patient cord edema.

Adult↗
PubMed1995

[The postoperative cervical spine and evaluation of the spinal cord with magnetic resonance tomography].

We present the cases of ten patients who underwent postoperative magnetic resonance assessment after dislocation injuries of the cervical spine and treatment with anterior interbody fusion and titanium implants. Eight patients had spinal cord injuries and two had nerve root disorders. In two patients who had intracranial haematomas and dislocation fractures of the cervical spine, MRI proved useful for identification of parenchymal spinal cord injuries as the reason for transverse lesions. Severe MR findings of the parenchymal spinal cord injuries (haematoma or transection) correlated with complete transverse lesions (4 patients) and oedema of the spinal cord, with incomplete transverse lesions (3 patients). MR enables us to examine the spinal cord after operations to ensure that correct spinal cord decompression has been achieved (3 patients). MRI is useful for detecting disc protrusion or chronic spinal stenosis in patients with titanium implants. All in all, MRI is an important modality in the evaluation of the posttraumatic cervical spine.

Adult↗
PubMed1995

Released PMN elastase: an indicator of postsurgical uneventful wound healing and early inflammatory complications. A contribution to the search for objective criteria in wound healing monitoring.

Monitoring of postoperative wound healing is important for the early diagnosis of postoperative infective complications in order to decrease morbidity. The purpose of this study was to search for a discriminatory time point between uneventful wound healing and early wound infections after operations for orthopaedic trauma using PMN elastase. This proteolytic enzyme is a biochemical marker for pathological granulocyte stimulation. The two groups of injured patients comprised persons with 'per priman' (pp) wound healing without complications--group 1 (N = 31)--and the early manifestation of a bacterial wound infection 'per secundam' (ps) during the healing phase--group 2 (N = 4). In group 1, surgical trauma was accompanied by an increase in PMN elastase levels reaching the maximum within the first 3 postoperative days; values returned to normal on day 10. In group 2 PMN elastase median levels showed recurring increases throughout. No normal values were observed. There was a highly significant difference (P < 0.01) on days 4 and 5 in group 2 compared with the control group 1. Since PMN elastase can be determined on an autoanalyser, and the enzyme is of proven discriminatory value, it is suggested that this marker should become part of the daily diagnostic routine in the care of the injured.

Adult↗
PubMed1994

[The unreamed tibial intramedullary nail in treatment of tibial fractures--initial experiences].

The unreamed tibial nail (UTN) combines the advantages of the external fixator (preservation of the cortical blood supply) with that of conventional intramedullary nailing (closed system, high patient comfort, no pin problems) in the treatment of the lower leg fracture [5]. Within 1 year (III/92 to III/93) 31 closed and 2 open fractures were stabilised with UTN. In 67% (22 persons) we found fractures of the A1, A2 and A3 types according to the AO classification. In 6 patients there was a combined lesion with involvement of the ankle joint. A follow-up of 27 patients was done, extending to an average of 6 months postoperatively. The clinical and radiological results were excellent in 26; average fracture healing time was about 12-14 weeks.

Adolescent↗
PubMed1994

Polymorphonuclear leucocyte migration response in uneventful wound healing following trauma surgery. A contribution to the search for objectifiable criteria in wound healing monitoring.

In a study of the clinical importance of polymorphonuclear granulocytes (PMN) for the monitoring of wound healing we investigated the postsurgical course of nine patients all of whom had undergone trauma surgery and had no wound complications. The "stimulated random PMN locomotion" was evaluated by a new migration filter device which preserves the cells in their genuine priming state, simulating in vivo conditions. The percentage of all activated PMN, expressed by the total migration index (TMI) reflected the highest median immediately after surgery (Zmax = 30.1%) and dropped to the lowest value on day 13 (Zmin = 13.9%). The mean invasion depth (T/2) of the cells along the migration distance into the filter showed only slight variations over time. The neutrophil migration activity (NMA), described by T/2 and TMI, behaved in a similar way to TMI. In studying physiological healing, preliminary results indicate that TMI, which expresses PMN activation, is an efficient tool in the postoperative monitoring of patients, and might in the future serve as a basis for an early warning system for wound healing complications.

Adult↗
PubMed1994

Dorsal stabilization of thoracolumbar spinal instability. Comparison of three different implantation systems.

Many unstable fractures and fracture dislocations of the lower thoracic and the lumbar spine are treated operatively. Internal fixation is mostly done via a posterior approach, anchoring the screws in the pedicles of the vertebrae. In the Traumatology Section of the Department of Surgery, Graz University, three different implantation systems have been employed in recent years. Sixty of all the patients operated on were available for follow-up an average of 36 months after operation. We compared them with respect to type of implant, paying special attention to any loss of reduction.

Adolescent↗
PubMed1994

Post-traumatic dynamic change of carboxyterminal propeptide of type I procollagen, alkaline phosphatase and its isoenzymes as predictors for enhanced osteogenesis in patients with severe head injury.

Patients suffering from severe head injury and fractures of long bones or large joints often show enhanced osteogenesis, with hypertrophic callus formation and/or heterotopic ossifications. The advantage of this phenomenon is early consolidation of the fractures. An extreme disadvantage is extensive periarticular calcification, resulting in complete ankylosis of the affected joint. In spite of numerous efforts aimed at clarifying the way in which severe head injury can influence osteogenesis at a distant site, this phenomenon is still not understood. The process, once started, seems irreversible, but if diagnosed in time, could be prevented with non-steroid anti-inflammatory drugs that inhibit development of heterotopic ossifications. The major prerequisite for testing this possibility is to define parameters of an early diagnosis of enhanced osteogenesis. Thus, the aim of this study was to test whether serum values of some parameters related to bone regeneration could allow an early prediction of enhanced ossification following bone fracture in patients with severe head injury. Samples of sera were obtained from three groups of injured patients: fractures of long bones or large joints only (n = 6), severe head injury only (n = 8), severe head injury and fractures of long bones and large joints (n = 7) and from a group of apparently healthy volunteers (n = 10). The values for alkaline phosphatase (ALP), the bone isoenzyme, and the carboxy terminal propeptide of type I procollagen (PICP) were significantly higher (5-20 times as high) in patients with severe head injury and bone or joint fractures than in any other group. Significantly increased concentrations of PICP were already found in the 1st week after injury, and those of ALP and of the bone isoenzyme increased during the 2nd week after injury. Results show that these parameters are helpful for an early diagnosis of enhanced osteogenesis and heterotopic ossifications in patients with severe head injury and bone fractures. Further studies are necessary to verify these findings, while analysis of reasons for the specific patterns of dynamic change of these parameters could lead to better understanding of the mechanisms underlying the uncontrolled bone formation.

Adolescent↗
PubMed1994

Basic fibroblast growth factor (BFGF) immunoreactivity as a possible link between head injury and impaired bone fracture healing.

Healing of fractures of long bones or large joints is often accelerated in patients with severe traumatic brain injury (TBI). However, in these patients an early fracture healing is accompanied by hypertrophic callus formation or heterotopic ossifications which might even result in an ankylosis of the affected joints. It seems that enhanced osteogenesis in patients suffering from TBI could be caused by some humoral factors, since the sera of these patients strongly promote the growth of osteoblast cells in vitro. However, humoral growth promoting factors which could perhaps induce enhanced osteogenesis are not yet identified. Hence, the aim of this study was to analyse if basic fibroblast growth factor (bFGF) could be related to the phenomenon of enhanced osteogenesis, since bFGF stimulates the growth of osteoblasts in vitro and could be found both in the brain and the bone tissue. For that purpose the values of bFGF immunoreactivity were determined in the sera of patients with TBI and bone fractures (n = 8) as well as in the sera of patients with either TBI alone (n = 10) or bone fractures alone (n = 7), during a period of three months after injury. Quantification of the bFGF immunoreactivity was done using the ELISA based on monoclonal antibodies raised against the recombinant human bFGF. The bFGF immunoreactivity values obtained were also compared with the values determined in the sera of normal, healthy persons (n = 9). In the group of patients with bone fractures alone only a transient increase of bFGF immunoreactivity (threefold above the normal values) was observed in the second week after injury. A similar increase of the values of bFGF immunoreactivity was also determined in the sera of patients with TBI only, but it lasted longer (from the 1st until the 7th to 8th week after injury). In the case of patients with TBI and bone fractures a specific pattern of post-traumatic dynamic change of the values of serum bFGF immunoreactivity was observed. Namely, the increase of bFGF immunoreactivity (up to seven-fold above the normal values) was determined even during the first week after injury. Afterwards, periods of high values of bFGF immunoreactivity observed during the 2nd, 4th and the 7-10th weeks after injury were interrupted by sudden decreases even to the normal values (during the 3rd and the 5-6th week after injury).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1993

MR findings and treatment of four patients with cervical spinal cord injuries.

We report the value of magnetic resonance imaging (MRI) in the assessment of cervical spine injuries with neurological deficit and the implications such information might have in the management of acute spinal cord injuries. Four cases are presented that were neurologically classified according to the 5-step Frankel scale. Three patients presented with an intramedullary hemorrhage. One of these patients showed additional mild compression of the spinal cord due to a retropulsed bony fragment, and one an epidural hematoma without any evidence of spinal cord compression. The fourth patient had compression of the spinal cord secondary to bony fragments from a burst fracture. We carried out two decompressions of the spinal cord by removing the disc and bony fragments. In addition, we performed two interbody fusions. In one patient we applied a halo vest, and in one case surgical intervention was not necessary after MRI assessment.

Cervical Vertebrae↗
PubMed1993

[Experiences with the Steffee variable screw placement system in fractures of the thoracic and lumbar spine].

The variable screw placement (VSP) system was first used in orthopaedic surgery. In recent years, this rigid screw-plate system has been implanted with increasing frequency in patients with traumatic instabilities of the thoracolumbar spine. At the University Hospital in Graz, 20 patients have been operated on in the Department of Surgery using this system, and 15 of them have been followed up some months after the hardware removal. The results are compared with those achieved in patients whose instabilities were stabilized with other implants.

Adolescent↗