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Biomedical subjects

P E Haers

Publications and source records attributed to P E Haers.

At least 19 recordsLinked to original sources
PubMed2000

The role of a posteriorly inclined condylar neck in condylar resorption after orthognathic surgery.

Recently, it has been reported that a posteriorly inclined condylar neck is associated with condylar resorption following orthognathic surgery, although its role in resorption remains unknown. By cephalometric screening of 240 patients with Angle Class II occlusion 2 years after orthognathic surgery, 11 patients with postoperative condylar resorption were identified. The preoperative posterior inclination of the condylar neck and the surgical risk factors mentioned in the literature, particularly surgically induced counterclockwise rotation of the mandibular proximal segment were evaluated. In all 11 cases, the condylar neck was clearly inclined posteriorly. Counterclockwise rotation of the proximal segment was also observed in all cases, and it amounted to 6.7 degrees (2.5-12 degrees) on average. The contributing role of a posteriorly inclined condylar neck in connection with surgical mandibular movement in postoperative condylar resorption is discussed.

Adolescent↗
PubMed2000

Surgical risk factors for condylar resorption after orthognathic surgery.

OBJECTIVE: The purpose of this study was to look for surgical risk factors for condylar resorption after orthognathic surgery. STUDY DESIGN: Seventeen patients of a group of 452 patients who had undergone orthognathic surgery consecutively and who were in accordance with the inclusion criteria of this study showed postoperative condylar resorption (group I). Preoperative cephalometric characteristics and surgically induced movements of this group were compared with a control group of 17 of 452 patients (group II) in whom postoperative condylar resorption and skeletal relapse did not develop, despite mandibular retrognathism (ANB angle >4 degrees) and high mandibular plane angle (>40 degrees). RESULTS: The kind of osteosynthesis used was not significantly different between the 2 groups. The amount of surgical advancements and the vertical movements of the jaws were not significantly different between the 2 groups. However, the distal (P =.005) and proximal (P =.007) mandibular segments were rotated significantly further counterclockwise in group I. Surgically induced posterior condylar displacement occurred significantly more frequently (P =.007) in group I. CONCLUSIONS: Counterclockwise rotation of the distal and proximal mandibular segments and surgically induced posterior condylar displacement seem to be important surgical risk factors for postoperative condylar resorption. Therefore, these movements seem to be contraindicated in patients who are at high risk.

Adolescent↗
PubMed1999

The Le Fort I osteotomy as a surgical approach for removal of tumours of the midface.

Tumours of the midface and maxillary sinuses have been removed via multiple approaches. The most common approaches are those using incisions in the facial skin, especially in the case of malignant tumours. The Le Fort I procedure via an intraoral incision as described by Sailer in 1986 is a versatile alternative. Combined with a coronal approach and various osteotomies of the upper face it also allows removal of tumours extending into the orbits, the nasoethmoidal complex and the skull base. The versatility of the Le Fort I osteotomy as a surgical approach was analysed in 17 cases. This method is reliable and gives excellent access. Further advantages are the wide surgical exposure and the clear visibility of the resection margins, the absence of visible scars, the feasibility of combining this approach with reconstruction using the buccal fat pad and the possibility of simultaneous placement of bone grafts, insertion of endosseous implants or other preprosthetic procedures via the same incision.

Adipose Tissue↗
PubMed1999

Update on bioresorbable plates in maxillofacial surgery.

Biodegradable materials, mainly polymers and copolymers of polylactide and polyglycolide, are today routinely used as fixation materials in craniomaxillofacial surgery. Several research groups have shown that these materials can adequately fix osteotomies and fractures of the craniofacial skeleton. Although there are some differences between polymers, in general their biocompatibility is good. They gradually lose their strength, enabling the underlying bone to take up the stress. Secondary procedures for removal of the material causing discomfort and pain are not needed. An overview of the development of biodegradable materials, their characteristics, and illustrations of different applications in craniomaxillofacial surgery are presented. More than 200 patients have been treated successfully so far in our units, the longest follow-up time being now over 7 years. The good results indicate that the use of bioresorbable fixation can be considered routine and will be definitely state of art at the beginning of the new millennium.

Absorbable Implants↗
PubMed1999

Multimodal strategy for reduction of homologous transfusions in cranio-maxillofacial surgery.

The transfusion of homologous blood carries well-known risks that have prompted efforts to develop alternative techniques. Such measures are of particular interest to patients undergoing elective procedures. A total of 204 patients, out of 1470 patients who consecutively underwent major craniomaxillofacial procedures under general anesthesia over a two-year period, were enrolled in a prospective protocol to reduce homologous transfusion requirements when a blood loss in excess of 500 ml was anticipated. The data were compared with the results of a retrospective control group (n=2890) covering major procedures during the previous four years, when blood-saving measures were applied occasionally, but not based on a global strategy. Techniques for the reduction of homologous transfusions were acute normovolemic hemodilution, controlled moderate hypotension, cell saver and predeposit autologous blood. In addition, preoperative administration of human recombinant erythropoietin was introduced during the last year of the study. These techniques were applied individually or in combination, depending on contraindications specific for each technique, using invasive monitoring in order to maintain intraoperative hemodynamic stability. The goal of this study was to examine the extent to which homologous transfusions may be reduced with the systematic application of transfusion-sparing techniques. Of 204 patients qualifying for the transfusion-sparing protocol, 30 received homologous transfusions. In comparison to the control group, utilization of transfusion-sparing techniques had doubled. The overall reduction in the use of homologous transfusions was highly significant. When acute normovolemic hemodilution, controlled moderate hypotension and the cell saver were used in combination, a greater reduction in homologous transfusions was achieved than with the use of either a single modality or combination of any two. No transfusions were required in patients pretreated with erythropoietin.

Adolescent↗
PubMed1999

Alternative methods for reduction of blood loss during elective orthognathic surgery.

Bimaxillary orthognathic surgery and genioplasty are frequently performed to correct dentoskeletal anomalies in otherwise healthy young patients. Until 1990 homologous blood transfusions were routinely necessary for these procedures. The present study describes a protocol of blood-saving measures that was adopted and tested on a continuous sample of 127 patients treated between 1994 and 1997. The protocol comprises acute normovolemic hemodilution, controlled moderate hypotension, positioning the surgical field above the heart level, cell saving, intraoperative homeostasis, preoperative autologous blood donation, administration of recombinant erythropoietin, and acceptance of a low hematocrit perioperatively. This study shows that homologous blood transfusions may be avoided intraoperatively by following the protocol described.

Blood Loss, Surgical↗
PubMed1998

[Preoperative diagnosis of complex craniofacial syndromes].

The aim of this study was to evaluate stereolithography as a tool in craniofacial surgery. The indications were classified according to the usefulness of stereolithography for different craniofacial pathologies. Stereolithography models of 21 patients were built; in three cases two models were made. The age of the 7 male and 14 female patients was 17 years on average (range: 15 months-44 years). First a helical volume CT scan of the anatomical region was performed. After transformation of the data set, the models were built by an SLA 250 stereolithography apparatus (3D-Systems, Valencia, Calif., USA), steered by FORM-IT/DCS-Software (University of Zurich, Switzerland). The stereolithography models were constructed by superposition of epoxy resin slices of 0.05 mm thickness, which were polymerized by a helium-cadmium laser. These models were classified according to the indication for stereolithography, the operation performed, the relevance for surgical planning and the usefulness for the fabrication of implants and protheses. In craniofacial syndromes, severe asymmetries of the viscerocranium, large skull defects and before surgical correction of hypertelorism these models provided important additional information for the surgeon. Before complex interventions in these fields the construction of a stereolithography model should be considered. In multiple fractures consolidated in dislocation, the models proved to be less useful.

Adolescent↗
PubMed1998

[Fronto-orbital corrections and development of the frontal sinus].

The development of frontal sinuses following bilateral fronto-orbital advancement is a topic of controversial discussion in the literature. In a retrospective study on 33 patients (15 girls and 18 boys) the development of the frontal sinus was examined radiologically. Only patients with a minimum age of 6 years and with at least 1 year of postoperative follow-up were included. The radiological reference for the frontal sinus development consisted of pneumatisation at or above the level of the supraorbital rims, as projected din postero-anterior cephalograms. According to these criteria a frontal sinus development was seen in 72.7% of our patients. There was no statistically proven correlation between sinus development and the sex of the patient, age at surgery or the amount of advancement. With the exception of severe cases of Crouzon's disease we usually expect normal development of the frontal sinus following bilateral fronto-orbital correction.

Child↗
PubMed1998

[Cranial development after corrective skull surgery in craniosynostosis].

Craniofacial development may be potentially implicated after vault corrections in cases of craniosynostosis. The aim of this prospective study was the investigation of the surgical effect on calvaria growth, correlating the percentiles of a group of patients before and after craniosynostosis correction in relation to the normal percentiles of growth. The patient population consisted of 71 children; the postoperative follow-up time in 57 patients was more than 12 months. Of the children followed up, 36 were male and 21 female. Thirty-six cases involved untreated non-syndromic craniosynostosis; the remaining 21 were syndrome cases. The patient ages ranged from 16 to 27 months. In 11 cases correction of an occipital craniosynostosis was carried out. The fronto-occipital circumference was registered in accordance with Prader's percentile table. The operative method included a fronto-parietal craniotomy, the temporary removal and shaping of the fronto-orbital band and a vault cranioplasty. During follow-up 13 patients treated with fronto-orbital advancement in cases of isolated craniosynostosis remained in the registered percentile curve. In 13 patients a change to a lower percentile curve was confirmed; 1 patient changed to a higher curve. In cases of syndromic craniosynostosis 10 patients remained in the post-operatively registered percentile curve; 8 patients changed to a lower and 1 patient to a higher percentile curve. No growth restriction of the reshaped calvaria after surgical correction of craniosynostosis was observed. No significant difference was found in the potential calvaria growth between syndromic and isolated craniosynostosis.

Child, Preschool↗
PubMed1998

[Occipital correction in scapho- and plagiocephaly].

The operation technique and the results after occipital correction in children with plagiocephaly and scaphocephaly are reported. The indication for the intervention is provided by aesthetic and functional considerations. The outcome is very good; the growth of the skull follows the same range of percentiles as preoperatively and normal mental development is seen.

Cephalometry↗
PubMed1998

The value of stereolithographic models for preoperative diagnosis of craniofacial deformities and planning of surgical corrections.

The purpose of this study was to assess the importance of stereolithographic models (SLMs) for preoperative diagnosis and planning in craniofacial surgery and to examine whether these models offer valuable additional information as compared to normal CT scans and 3D CT images. Craniofacial SLMs of 20 patients with craniomaxillofacial pathology were made. A helical volume CT scan of the anatomic area involved delivered the necessary data for their construction. These were built with an SLA 250 stereolithography apparatus (3D-Systems, Valencia, CA, USA), steered by FORM-IT/DCS software (University of Zurich, Switzerland). The stereolithography models were classified according to pathology, type of surgery and their relevance for surgical planning. Though not objectively measurable, it was beyond doubt that relevant additional information for the surgeon was obtained in cases of hypertelorism, severe asymmetries of the neuro- and viscerocranium, complex cranial synostoses and large skull defects. The value of these models as realistic "duplicates" of complex or rare dysmorphic craniofacial pathology for the purpose of creating a didactic collection should also be emphasized. The models proved to be less useful in cases of consolidated fractures of the periorbital and naso-ethmoidal complex, except where there was major dislocation.

Adolescent↗
PubMed1998

Development of the frontal sinus following bilateral fronto-orbital osteotomies.

The presence of frontal sinuses following bilateral fronto-orbital advancement is discussed controversially in the literature. In a retrospective study, 33 patients (18 male and 15 female) were operated on between 1982 and 1993, with at least one year postoperative follow-up and with a minimum age of 6 years at the end of the follow-up period following bilateral fronto-orbital remodelling, were included. The average age at which the procedure was performed was 29 months with a minimum of 3 months and a maximum of 7.8 years. The study presented shows a pneumatization of the frontal sinus in 72.7% of 33 patients following bilateral fronto-orbital advancement. The first radiographic signs of sinus development were detected between the ages of 4 and 11, average 8.3 years. There were no statistically proven correlations between frontal sinus pneumatization and age at operation or the amount of advancement or sex of the patients. Surgical enlargement of the cranium by frontal advancement with adequate stabilization results in an enlargement of the neurocranium, thereby decreasing pressure on the inner frontal cortex and allowing frontal sinus pneumatization to proceed normally. Hence, the development of a frontal sinus may be a reflection of the effectiveness of the surgical therapy.

Age Factors↗
PubMed1998

Biodegradable polylactide plates and screws in orthognathic surgery: technical note.

In orthognathic surgery, the bone fragments are usually fixed with metallic plates and screws. Metallic devices other than titanium plates are usually removed after the osteotomy has consolidated, which often requires general anaesthesia. Titanium plates, supposed to be biotolerable, have been introduced in order to overcome this need for secondary intervention. However, due to corrosion, titanium particles have been found in scar tissue covering these plates and in locoregional lymph nodes. Therefore, their removal is also advocated. Self-reinforced poly (L-lactide) homopolymer (PLLA) and poly (L/D-lactide) stereocopolymers with a L/D molar ratio up to 85/15 have sufficient strength to overcome the need for additional support for the fixation of fractures. The plates can be bent at room temperature. The surgical technique and early results of a case of bimaxillary surgery and genioplasty fixed with bioresorbable material without postoperative rigid maxillomandibular fixation are reported.

Absorption↗
PubMed1998

Biodegradable self-reinforced poly-L/DL-lactide plates and screws in bimaxillary orthognathic surgery: short term skeletal stability and material related failures.

Biodegradable self-reinforced poly-L/DL-lactide plates and screws were used for osteosynthesis in 10 consecutive cases of bimaxillary procedures with simultaneous genioplasties, without postoperative rigid intermaxillary fixation. During surgery, data were gathered concerning failure of the osteosynthesis material. Clinical examination was carried out weekly until the sixth postoperative week. Cephalometric analysis of standardized cephalograms was performed to evaluate the short-term skeletal stability pattern, which was compared with similar reports in the literature. Six weeks postoperatively, all jaws were clinically stable and there was no clinical evidence of foreign body reactions. For the whole group (n = 10), the mean maxillary advancement at point A was 2.9 mm with a mean postoperative relapse of 0.0 mm. The mean advancement at point B was 2.8 mm with a mean additional advancement postoperatively of 1.1 mm. The mean vertical surgical displacement at point A was directed inferiorly with a value of 1.8 mm and a relapse of -0.4 mm. At point B the corresponding values were 1.9 mm and -0.4 mm. In the Angle Class III group (n = 4), the mean advancement at A was 5.9 mm with an additional postoperative advancement of 0.3 mm. In the Angle Class II group (n = 6), mean advancement at point B was 4.0 mm, with an additional postoperative advancement of 1.1 mm. In the group with short face deformity (n = 3), the mean inferior movement in ANS was 6.6 mm with a relapse of -0.2 mm. At menton the vertical surgical movement was 13.0 mm with a relapse of -0.2 mm. None of the plates, which were bent at room temperature, broke. The screw heads broke or had an insufficient fit in the bone in 12 of 305 (3.9%) screws. It can be concluded that the tested system of biodegradable self-reinforced poly-L/DL-lactide screws and plates has a small material-related failure rate, and that their application in orthognathic surgery leads to a predictable short-term skeletal stability pattern which is comparable to the 'gold standard' of titanium plates and screws.

Absorbable Implants↗
PubMed1998

[Allo-transfusion saving measures in maxillofacial surgery].

In terms of a prospective clinical study between June 1994 and May 1996, in 204 patients undergoing maxillo-facial surgeries with a expected blood loss of more than 500 ml a protocol of bloodsaving measures was followed. By means of an additional retrospective study, the consumption of homologous blood and the amount of bloodsaving measures between June 1990 and May 1994 was evaluated. Bloodsaving measures were consisting from acute normovolemic hemodilution, controlled moderate hypotension, cell saving, preoperative autologous blood donation, and administration of rh-erythropoetine. The methoda were applied isolated as well as in combination. Special concerns were given to a stable intraoperative homeostasis and to the acceptance of a low hematocrit perioperatively. Aim of the study was to investigate if, following the protocol, even in major maxillofacial procedures homologous blood transfusions almost completely can be avoided. Out of the 204 patients in the prospective study, only 30 received homologous blood. For the period June 94 to May 96, the reduction of the number of patients receiving homologous blood in relation to the period June 90 to May 94 was 83%. The results indicate that in the years 94 to 96 twice as much patients received bloodsaving measures. These led to a reduction of homologous blood consumption for 427 units in 1990 to 56 units 1996 (p < 0.001). If three measures, i.e. normovolemic hemodilution, cell saving, and hypotension were combined, the need of blood transfusion was at the minimum level. The effective reduction of homologous blood transfusion by consequent application of bloodsaving measures can with these data obviously be demonstrated.

Adolescent↗
PubMed1996

Mandibular reconstruction with full thickness calvarial bone and temporal muscle flap.

Eleven patients underwent mandibular reconstruction with pedicled temporal muscle flaps combined with vascularised or free full thickness calvarial bone grafts. Six were primary and five secondary reconstructions. The indications were squamous cell carcinoma (n = 6), radio-osteonecrosis (n = 4), and gunshot wound (n = 1). Five patients also had endosseus implants, either simultaneously or delayed. The only major complications were necrosis of the whole calvarial bone (n = 1) and permanent facial nerve palsy (n = 1). The advantages of using full thickness calvarial bone are that it is thick enough to take an endosseous implant, morbidity is low, there is virtually no postoperative pain, the scar is invisible, and there is only one donor area for both hard and soft tissue. Transplantation of full thickness calvarial bone and temporal muscle is a viable alternative to an osseomyocutaneous microvascularised free flap for reconstruction of the mandible when the neck has been previously operated on or irradiated, and anastomosis may be critical.

Adult↗
PubMed1995

Mandibular resorption due to systemic sclerosis. Case report of surgical correction of a secondary open bite deformity.

Systemic sclerosis (SSc) is a connective-tissue disorder of unknown origin causing a multisystem disease. While erosions of the distal phalanges are commonly described, resorption of the mandible has been considered an unusual finding. However, systematic radiographic screening of different groups of patients suffering from SSc revealed a resorption incidence of 20-33% of the examined mandibles. Women especially seem to be affected, and the male/female ratio is 1/7. Bilateral condylysis due to SSc has been described in seven cases, or 13.7% of the reported cases. To the best of our knowledge, this is the fourth report of surgical correction of secondary dysgnathia due to systemic sclerosis and the first with a 2-year follow-up period.

Adult↗