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Biomedical subjects

T Pohlemann

Publications and source records attributed to T Pohlemann.

At least 19 recordsLinked to original sources
PubMed2001

Computer-assisted fracture reduction: novel method for analysis of accuracy.

Anatomic reduction of displaced fractures is limited by the chosen surgical approach and intraoperative visualization. Preoperative Computed Tomography (CT) enhances the analysis of the fracture pattern and provides accurate spatial relationships. Computer Assisted Surgery (CAS) was introduced to increase the accuracy of specific surgical procedures. CAS systems can be used for implant placement or osteotomies in intact bone or reduced situations prior to obtaining the CT data, as differentiation into different datasets related to specific fragments is not yet possible. We present a model that allows "virtual" controlled reduction, providing computer assistance during the fracture reduction. Prior to clinical application, the accuracy of the process of virtual reduction must be proven in an experimental setting. An in vitro fracture model with two body fragments and a motion tracking system for three-dimensional (3D) control (accuracy 0.1 mm and 0.1 degrees ) was used. Two methods were employed: direct visualization and reduction by the examiner, and "virtual" reduction, performed solely with the use of a computer image, in which the examiner lacks any direct visualization of the fragments. The results of this very simplified "fracture" model indicate that the overall difference between direct and virtual controlled reduction was very small. A significant difference of 0.3 mm (0-1.8 mm) was seen for the residual displacement represented by the Euclidean distance (p < 0.01), whereas the difference in the residual angulation was not significant (p > 0.05). The methods tested revealed that virtual controlled reduction is nearly as accurate as direct visualization. Reduction control utilizing a motion tracker system reveals accurate 3D information in this simplified reduction setup, and is now used as a standard setup for analyzing realistic fracture models.

Fracture Fixation↗
PubMed2001

Injuries of the pelvic ring in road traffic accidents: a medical and technical analysis.

Between 1985 and 1995, 9380 traffic accidents occurring in the area of Hannover, Germany, were analysed; 12428 individuals had been injured and 387 (3.1%) had sustained a pelvic-ring injury (AIS(PELVIS)>2). In 131 cases (34%), the injuries were further classified (Pennal and Tile) and a technical reconstruction made of the accident: 52% were type A, 27% type B and 21% type C injuries; 46% were in cars, 12% on motorised two-wheelers, 10% on bicycles and 1% in utility vehicles; 31% were pedestrians. Pelvic-ring injuries occurred in restrained vehicle occupants in accidents with a (delta)V of more than 30 km/h, whereas they occurred in a considerable proportion of unrestrained vehicle occupants, pedestrians and bicyclists at lower (delta)V or collision speed. The percentage of B- and C-type injuries increased in crashes with higher (delta)v or collision speed. In addition to further improvements of the passive safety, lower collision speeds or (delta)V would reduce or prevent pelvic-ring injuries. Due to the small number of occupants protected by airbags in this study, their protective effect for the pelvis could not be assessed. The reconstruction of pelvic-ring injury mechanism in traffic accidents is possible when technical and medical factors are considered.

Accidents, Traffic↗
PubMed2001

Primary subtalar arthrodesis of calcaneal fractures.

We evaluated retrospectively the long-term results of isolated calcaneal fractures treated with open reduction and internal fixation and a primary subtalar arthrodesis. From 1990 to 1997 258 patients were treated with a calcaneal fracture, for the current study six patients were included. Six different surgeons operated on the patients. The indication for the fusion was based on the comminution of the posterior facet according to the preoperative CT as well as the intraoperative evaluation of destruction of the cartilage. The restoration of length, axes and angles of the calcaneus was almost anatomical in all cases. Follow-up was done at a mean of 4.9 (2.5 - 7.5 years). Using the AOFAS score, the results were good or excellent in five patients. In one patient with a painful arthritis in the talonavicular joint and hyperesthesia of the sural nerve, the results were fair. All returned to their profession within 9 months and had no or only minor daily restrictions. The results are comparable with single surgeon series. We found open reconstruction of the calcaneus with primary fusion of the subtalar joint may be indicated in selected patients and, in these 6 patients led to good results.

Arthrodesis↗
PubMed2000

[Acceleration related injury of the cervical spine in restrained car drivers. Frequency, causes and long-term results].

In an analysis of 3,838 restrained car drivers, the proportion of acceleration related injury of the cervical spine increased from under 10 % in 1985 to over 30 % in 1997. These injuries occurred mainly in the case of head-on or multiple collisions. Letters were sent to 1,136 of the injured persons, and of the 138 patients who returned the questionnaires, 121 (88 %) were still suffering from their symptoms. It was a question of pain (74 %), tension (6 %) and stiffness (5 %) in the head (27 %), neck (55 %) and shoulder (8 %) area. The duration of the complaints was the longest after multiple collisions. In addition to a slight influence of the accompanying injuries on the duration of complaints, the individual constitution seems to be an important determining factor. In order to resolve the difficulties of conducting of this retrospective study, prospective studies are necessary which include documentation of diagnosis, treatment protocols, duration and type of complaints.

Accidents, Traffic↗
PubMed2000

[Mechanism of pelvic girdle injuries in street traffic. Medical-technical accident analysis].

During 1985 and 1993, 7,410 persons were injured in traffic accidents in the area of Hanover. Of these, 306 (4.1%) sustained a pelvic girdle injury. In 139 cases (45%), the pelvic girdle injuries were further classified (Pennal and Tile) and a technical reconstruction of the accident situation was performed. 52% were type A, 27% type B and 21% type C injuries. Some 47% of the casualties were vehicle occupants, 31% pedestrians, 12% motorcyclists and 10% cyclists. In restrained vehicle occupants pelvic girdle injuries occurred mostly in accidents with a delta-v of more than 30 km/h, whereas in unrestrained vehicle occupants, pedestrians and cyclists they also occurred with lower delta-v or collision speed. The percentage of type B and C injuries increased with higher velocities. In addition to further improvements in passive safety, lower collision speed or delta-v is necessary to reduce or prevent pelvic girdle injuries. The reconstruction of pelvic girdle injury mechanism in traffic accidents is possible, when both technical and medical parameters are considered.

Acceleration↗
PubMed2000

[3-dimensional movement analysis after internal fixation of pelvic ring fractures. A computer simulation].

Several studies exist describing the biomechanical behavior of several external or internal fixation techniques of the posterior and anterior pelvic ring. Recently, the traditional models using isolated anatomical sections or fixed pelvic ring specimens for evaluation of linear or two-dimensional data have been replaced by three-dimensional measurement systems and simulations of muscle forces. These studies have contributed important information to the understanding of the biomechanics of the intact and injured pelvic ring, however, a consequent movement analysis is still missing. In the present study, 3-D data acquired during several series of testing implants for stabilization of the posterior pelvic ring (sacrum: sacral bars, sacral plates, transiliosacral lag screws; Sl joint: anterior plates, transiliosacral lag screws), using a complete pelvic ring model with single leg stance and static abductor muscle simulation, were converted into a commercially available 3-D animation package. By use of simple graphical representation of anatomical elements of the posterior pelvic ring, reproducible and reliable movement patterns for different types of stabilization could be identified, which demonstrated potential "weakness" of the fixation before failure occurred. These movements were analyzed by "replay functions" and were comparable to observations during the original experiment. The following movements were observed. Sacral fracture, transforaminal: (1) rotation of the transiliosacral lag screws around its axis, even with a second screw into S1; (2) Sacral bars: shearing with compression of the cranial-posterior fracture zone; (3) Sacral plates: minimal translation in the proximal fracture zone and distraction in the distal fracture line, effectively compensated by an additional plate at the S3 level. Sl joint disruption: (1) anterior plating (two plates), minimal translation in the plane of the Sl joint; (2) transiliosacral lag screws, rotational movement around the axis of the screws with only minimal movement at the S1 level. The provided information confirmed the observations and allowed a more detailed and comfortable examination of movement patterns. A better understanding of potential "failure zones" might be useful to optimize the dimensions, design, and the positioning of implants for the pelvic girdle. For further studies, more complex computer models including finite element technology might be useful to add accessory information and could result in a decreased need of living specimen testing.

Biomechanical Phenomena↗
PubMed2000

Whiplash-type neck distortion in restrained car drivers: frequency, causes and long-term results.

An analysis was made of 1176 whiplash-type neck distortions taken from a total of 3838 restrained car driver incident reports. The percentage of whiplash-type neck distortion among injured drivers increased from less than 10% in 1985 to over 30% in 1997. Most occurred in head-on crashes or crashes with multiple collisions; only 15% occurred in rear-end collisions. More than 1,000 questionnaires were sent to the injured to find out about the duration and type of complaints caused by their cervical spine injury. Although only 138 (12%) returned the questionnaire, which may not be a representative sample, a further analysis was carried out. Of the 138, 121 (88%) indicated that they had suffered or were still suffering from their symptoms. The percentages of the various complaints were as follows: pain (74%), tension (6%) and stiffness (5%) in the head (27%), neck (55%) and shoulder (8%). The duration of the complaints was longest after multiple collisions and when the onset of complaints was longer than 24 h after trauma. Women and elderly persons predominated slightly in the group with longer duration of complaints. A correlation between the severity of the accompanying injuries and duration of complaints was found. Lack of adequate follow-up for patients with less severe injuries posed considerable difficulties for this retrospective study. In order to better evaluate this problem, prospective studies are necessary, with documentation including diagnosis, treatments, complaint duration and type.

Accidents, Traffic↗
PubMed2000

[Classification, staging, urgency and indications in pelvic injuries].

For primary evaluation, classification and indication of pelvic ring injuries the exact knowledge of the injury mechanism and the clinical and radiological signs is mandatory. Clear injury definitions are proved for prognostical reasons and for the timing of the specific treatment. The simple classification of stable A-type injuries, rotational B-type injuries and translationally stable C-type injuries is the basis for further treatment. Whereas A-type fractures normally need no surgical stabilization, except in severely displaced fractures or possible organ injuries due to fracture fragments, in B-type injuries solely stabilization of the anterior pelvic ring provides sufficient stability for early ambulation with partial weight bearing. In C-type injuries a combined posterior and anterior stabilization is required for anatomical reduction and early ambulation. With this concept the pelvic girdle can be reconstructed anatomically in the majority of cases.

Early Ambulation↗
PubMed2000

Hip dislocation in patients with multiple injuries. A followup investigation.

The combination of traumatic hip dislocation and multiple trauma have not been well documented in the medical literature to date. The role of surgery therefore has not been well defined in these patients. During a 12-year period, 29 consecutive patients with 31 traumatic hip dislocations with concomitant Injury Severity Scores exceeding 18 points were treated at the authors' institution. An initial satisfactory closed reduction was achieved in 23 patients, two patients had failed reductions, and four patients had noncongruous reductions. Open surgical procedures were done on these patients and on 10 additional patients who had associated acetabular or femoral head fractures. Overall, seven patients from the group died including two patients who had surgical procedures. From 17 living patients who did not require surgery for failed or noncongruous reductions, 13 patients were available for followup at a mean of 8 years after their injury. The clinical results at this followup were excellent in three hips, good in seven hips, and fair in four hips. The radiologic results, however, showed that five patients had early (Grades I and II according to Matta) hip degeneration and seven patients had Grade II (according to Ficat) avascular necrosis of the femoral head. These changes were not clinically significant at this followup and it is proposed that these results justify a policy of active treatment of traumatic hip dislocation in patients with multitrauma.

Adolescent↗
PubMed2000

Pelvic fractures in pregnant multiple trauma patients.

OBJECTIVE: To study the outcome of pelvic fractures and fetuses in pregnant patients involved in blunt multiple trauma. DESIGN: Retrospective follow-up study. SETTING: Level I trauma center. PATIENTS: Pregnant multiple trauma patients with pelvic fractures between 1974 and 1998. INTERVENTIONS: Conservative and operative treatment of pelvic fractures adapted to the clinical status of the mother. MAIN OUTCOME MEASURES: Clinical, functional, and social outcomes were evaluated. RESULTS: Out of 4,196 patients with blunt multiple trauma treated between 1974 and June 1998, seven demonstrated the combination of blunt multiple trauma, pregnancy, and pelvic fractures. These patients had a mean Injury Severity Score of 29.9 points. Five mothers and three fetuses survived their injuries. All dead fetuses died on the scene. One surviving fetus was found to have hydrocephalus unrelated to the injury; the remaining fetuses had an uneventful delivery and were healthy. In two of the three patients whose fetuses survived, the treatment of the pelvic fracture was modified for the sake of fetal well-being. In all of these patients, acceptable outcome was achieved. CONCLUSION: Modification of the treatment of the pelvic fracture in pregnant women with multiple trauma may be necessary to minimize the risk of fetal injury. In our experience with these rare cases, this modified treatment did not severely alter the clinical outcome of the mother's pelvic fracture.

Acetabulum↗
PubMed2000

Facts about the disaster at Eschede.

On June 3, 1998, at 10:59 a.m., a high-speed train (Intercity Express, ICE) traveling at 200 kilometers per hour collided with a bridge at Eschede, Germany, causing it to collapse. The force of the collision, combined with the speed of the train's rear engine, propelled the rear wagons into the structure. The accident caused 101 deaths and 103 injuries. Four minutes after the accident, the alarm was reported; sixteen minutes after the accident, the first doctor on emergency call was on the scene, arriving from Celle, approximately twenty kilometers away. In the first four hours after the crash, different rescue organizations brought a total of 1,844 people to the accident site, including 461 ambulance personnel and paramedics. Thirty-nine aircraft, including helicopters and army aircraft, were available at the scene. Ninety-five passengers passed away on site. Many of the surviving passengers had multiple injuries and were stuck in the train; although they had to be rescued from the severely damaged wagons, all patients, with one exception, were on the way to hospitals by 12:55 p.m. The casualties were distributed among twenty-two hospitals; two victims later had to be transferred to other hospitals for medical reasons. This paper details the factors that were responsible for the success of the rescue operations at Eschede.

Disasters↗
PubMed1999

[The value of CT in classification and decision making in acetabulum fractures. A systematic analysis].

UNLABELLED: The classification of acetabular fractures and especially the diagnosis of additional lesions can be misleading, when the personal experience is limited and the decisions are based only on conventional radiographs. The introduction of Spiral-CT with multiplanar reformations and 3-D views has improved the quality of visualization. Due to their higher costs, the need of these additional diagnostic tools is frequently questioned. This paper discusses the relevance of plain radiographs, 2-D-CTs, 3-D-CTs and Femursubtraction-CTs (FsCT) for the classification of acetabular fractures, based on a controlled study. METHODS: Thirty physicians with different levels of experience in acetabular surgery were divided in three groups of 10 each: group I comprised residents without operative experience in acetabular surgery, group II was physicians with 3-10 years of operative experience, and group III was experts in acetabular surgery. A total of 10 complete radiographic cases of high quality providing all levels of preoperative diagnostics (plain radiographs, 2-D-CT, CT with multiplanar reformation, 3-D-CT, Fs-CT) of different acetabular fracture types were prepared. The task for each candidate was to classify the fracture according to Letournel and to identify all additional injuries within the hip joint (e.g. marginal impaction, head fractures, etc.). The different diagnostic "levels" could be ordered stepwise according to personal need and no time limit was given. The case was finished when the candidate presented his final diagnosis. The use of the different radiographs, the preliminary diagnosis, the changes in diagnosis, and the final decisions were recorded. These findings were correlated with the different levels of experience and against a "consensus classification" which was generated by thorough discussion, and the use of intraoperative information and postoperative radiographs not accessible to the candidates. RESULTS: The "correct" fracture classification based on plain radiographs was: group I, 11%; group II, 32%; group III, 61%. Based on 2-D-CT a "correct" diagnosis was reached by 30% in group I, by 55% in group II, and by 76% in group III. With consideration of the "transient forms" in acetabular fractures based on Letournel and the 3-D-CT used mainly by group I, the rate of "correct" classifications rose to 65% in group I, 64% in group II and 83% in group III. The modifiers were diagnosed "correctly" in group I by 37%, in group II by 56%, and in group III by 73%. The use of the 3-D-CT and especially the Fs-CT by group I resulted in an improvement in the rate of correct classifications to 61%, whereas in group II the Fs-Ct was used only exceptionally. The 2-D-CT was the basis for the diagnosis of the additional lesions in acetabular fractures within all groups resulting in 73% complete diagnoses in group III. This study showed the importance of CT for the exact analysis and classification of acetabular fractures. In particular, the secondary reformations in CT and the 3-D-views dramatically improved the rate of "correct" classifications in the group of surgeons with limited personal experience in acetabular surgery. This allows the less experienced an acceptable level of "correct" diagnoses, so that the treatment options can be weighed correctly. Among the "experts" a rate of divergent classifications of approximately 20% was observed, especially in "transient" forms of acetabular fractures.

Acetabulum↗
PubMed1999

[Osteonecrosis of the femoral head after osteosynthesis of a proximal femur fracture with a 95 degree condylar plate].

Avascular necrosis of the femoral head is a frequent complication after osteosynthesis of femoral neck fractures. It is rarely seen after proximal femur fractures with intact trochanteric area. The choice of the implant varies from different blade systems (DHS, DCS and condylar plates) to intramedular nailing systems (gamma nail, classic nail). The complication of avascular necrosis of the femoral head after internal fixation of sub-trochanteric and proximal femur fractures is reported following intramedullary nailing. We report a case of a femoral head necrosis after osteosynthesis of a proximal femur fracture with a 95 degree condylar plate.

Adult↗
PubMed1999

Long-term outcome in children with fractures of the proximal femur after high-energy trauma.

BACKGROUND: Fractures of the femoral head and neck in children have a risk of severe complications, especially femoral head necrosis. We performed a long-term follow-up study of patients treated at our institution. METHODS: Patients were reexamined at least 3 years after trauma and were included if they were younger than 17 years old at the time of injury, if there was no history of previous fracture, and if there was no history of underlying bone disease. Fractures were classified according to Delbet, and outcome was graded according to Ratliff. Anterior capsulotomy was not performed, and stabilization devices were placed short of the epiphysis except for type I fractures. RESULTS: Of 32 patients, 28 were reexamined. Among these patients, the mean age at the time of injury was 11.8 years and the mean follow-up time was 11.1 years (range, 3-21 years). There were 3 patients with type I fractures, 8 patients with type II fractures, 12 patients with type III fractures, and 5 patients with type IV fractures. Thirteen patients had Injury Severity Scores > 18. At last follow-up, 20 patients presented with good function, 5 with fair outcome, and 3 with poor results; all of the latter suffered type I fractures. Eighteen patients had no restrictions in activities of daily living or during sports activities. In six other patients, the inability to participate in sports was attributable to head trauma, amputation, or peripheral neurologic damage. CONCLUSION: We found favorable long-term outcome in type II to type IV fractures. In these patients, restrictions of function were usually caused by other associated injuries. All patients with type I fractures presented with poor outcome secondary to their proximal femoral fractures, and not because of other associated injuries. Type I fractures during childhood and adolescence represent an unsolved problem.

Accidents↗