Accessory joints between basiocciput and atlas/axis in the median plane

To explore the many osseous irregularities that are found in the area between the basiocciput, the anterior arch of the atlas and the tip of the dens axis we studied 99 cadaver specimens using magnetic resonance tomography (MRT), computed tomography (CT), median saw-cut sections, and histological sections. Additionally, "dry" specimens of the skull (n = 110), atlas (n = 56), and axis (n = 33) were investigated. In the median plane, the dry and cadaver specimens exhibited osteoarthritis-related osseous outgrowths and osteophytes of the articular surfaces of the median atlanto-axial joint (n = 63), and the presence of congenitally developed free ossicles (n = 22) and of third occipital condyles (n = 3). The largest osteophytes (giant osteophytes) (n = 4) of the anterior arch of the atlas formed osseous contact zones with the basiocciput that were visible histologically as real joints and were designated accessory median atlanto-occipital joints. The third occipital condyles also formed osseous contact zones, visible histologically as real joints, with the anterior arch of the atlas or with the tip of the dens, and were designated accessory atlanto-occipital or occipito-odontoid joints. Frequent free ossicles, incorporated into the accessory joint, were found by histological examination to be covered with hyaline cartilage.

[Minimally-invasive computer-assisted fluoroscopic navigation for kyphoplasty]

AIM

The transpedicular placement of a hollow needle into vertebral bodies for kyphoplasty requires utmost accuracy and thereby permanent multiplanar X-ray control. Facing the increasing number of vertebral compression fractures, the aim of this work was the implementation of computer-assistance to optimise the issue. Prior to clinical implementation, experimental trials were undertaken to analyse the quality-improving options of the technique.

METHOD

The virtual image of the planning and the puncture were correlated with the postoperative X-ray image of the needle. The real canal in the bone was then correlated with the preoperative planning in a CT-based 3D model and differences were calculated. As a measure of accuracy the deviation of the needle from the ideal intruding vector and the distance between its top and the centre of a predefined target were scrutinised and related to the indications of the navigation system. Operating time, radiation exposure and general applicability were additionally assessed. All data were compared with those of a conventional control group.

RESULTS

Planning and navigation could be executed with high accuracy. With an exactly transpedicular approach, neural structures were safely circumnavigated without once missing the target. In the control group the distance fault was up to 9 mm. The navigated drilling differed from the ideal trajectory by 1 degrees to max. 4 degrees. Conventional C-arm control led to a divergence of 4 degrees to 8 degrees . Radiation exposure could be reduced through computer assistance by 76 % to a fourth of the conventionally resulting amount and the pure operating time thereby decreased by 40 %. The inconvenient course of repeated positioning of the C-arm was overcome.

CONCLUSION

In challenging cases of deteriorated anatomy and difficult radiomorphologic orientation, especially of the lower thoracic spine, the CAOS-procedure succeeds in finding the optimal pedicular approach to the vertebral body, helps to avoid collateral damage and minimises the overall risk of the procedure. High accuracy and reduced radiation exposure justify the clinical use of fluoroscopic navigation for transpedicular instrumentation.

[Infection transfer between the maxillary sinus and endocranium]

BACKGROUND

Rhinogenous brain abscesses usually originate from a frontal sinusitis, rarely from the ethmoidal system or the maxillary sinus. However, there are different pathways that can lead to the transfer of a maxillary infection to the endocranial compartment.

PATIENT

A patient with frontal brain abscesses originating from a maxillary sinus infection is presented and diagnostic steps, therapy as well as pathophysiology are discussed.

PATHOPHYSIOLOGY

The venous plexus of the maxillary sinus drains through the posterior wall of the antrum of Highmore into the deep facial vein that leads into the pterygoid plexus and then through the rete foraminis ovalis into the cavernous sinus. In addition, numerous small veins perforate the osseous roof of the maxillary sinus and enter the orbit joining the superior or inferior ophthalmic vein. They are also connected to the cavernous sinus or the pterygoid plexus. A number of veins perforate the anterior wall of the maxillary sinus communicating with the angular vein that drains into the superior ophthalmic vein and into the cavernous sinus. From the cavernous sinus, the blood arrives at the deep middle cerebral vein that usually communicates through the white substance towards the brain's superficial venous system.

CONCLUSION

The presence of these maxillo-cerebral venous anastomoses explains the spread of infection from the maxillary sinus to the white substance of the brain without any direct association with the base of the skull.

Anatomical and biomechanical investigations of the iliotibial tract

Divergent descriptions of the anatomic location and biomechanical function of the iliotibial tract (IT) can be found in the literature. This study attempted to obtain exact data regarding the anatomic course and material characteristics including the biomechanical properties of this structure. The following were its aims: (1) anatomical investigations of the IT; (2) mechanical properties of the IT; (3) femoral head centralizing force of the IT and subligamentous forces in the height of the greater trochanter in different joint positions by using a custom-made measuring prosthesis and a subligamentous positioned sensor; (4) construction of a finite element model of the proximal femur including the IT and measuring the femoral neck angle under variation. The hip joints and IT in a total of 18 unfixed corpses were evaluated. We studied the anatomic relationship to surrounding structures, as well as the material properties with the help of tensile strength testing utilizing an uniaxial apparatus. During the test, a load-displacement curve was registered, documenting the maximum load and deformation of the IT. To measure the subligamentous pressure at the height of the greater trochanter, a custom-made sensor with a power-recording instrument was constructed. Furthermore, an altered hip prosthesis with a pressure gauge at the height of the femoral neck was used to measure the forces which are directed at the acetabulum. The investigations were done in neutral-0 position and ab/adduction of the hip joint of the unfixed corpse. In addition, we varied the femoral neck angle between 115 degrees and 155 degrees in 5 degrees steps. To confirm the subligamentous forces, we did the same measurements intraoperatively at the height of the greater trochanter before and after hip joint replacement in 12 patients. We constructed a finite element model of the proximal femur and considering the IT. The acquisition of the data was done at physiological (128 degrees), varus (115 degrees), and valgus (155 degrees) femoral neck angles. The influencing forces of the IT at the height of the greater trochanter and the forces at the femoral head or the acetabulum could be measured. Our anatomical investigations revealed a splitting of the IT into a superficial and a deep portion, which covers the tensor fasciae latae. The tensor fasciae latae has an insertion on the IT. The IT continues down the femur, passing over the greater trochanter without developing an actual fixation to the bone. Part of the insertion of the gluteus maximus radiates into the IT. The IT passes over the vastus lateralis and inserts at the infracondylar tubercle of the tibia or Gerdy's tubercle, at the head of the fibula, as well as at the lateral intermuscular septum. Portions also insert on the transverse and longitudinal retinaculum of the patella. Concerning the material properties of the IT, we found a structural stiffness of 17 N/mm extension on average (D = 17 N/mm). The subligamentous measurements at the height of the greater trochanter in the unfixed corpse and intraoperatively during hip joint replacement showed an increase of the forces during adduction and a decrease during abduction of the hip joint. We found thereby a maximum increase up to 106 N with 40 degrees adduction. Concerning the femoral neck angle, we can state that valgus leads to lower subligamentous forces and varus to higher subligamentous forces. The forces directed at the acetabulum, which were measured by the prosthesis with a sensor along the femoral neck, showed a decrease with varus angles and an increase with valgus angles. The highest force of 624 N was measured with 40 degrees adduction and an angle of 155 degrees. The finite element model of the proximal femur showed a sole hip joint-centralizing force of the IT of 655 N with a femoral neck angle of 128 degrees after subtraction of the gluteal muscle force and the body weight. At 115 degrees, we found an increase up to 997 N and a decrease to 438 N at 155 degrees. Concerning the resulting forces in the acetabulum, we found opposite forces in comparison with the force of the IT at the height of the greater trochanter: at 115 degrees, a femoral head-centralizing force of 1601 N; at 128 degrees, 2360 N; and at 155 degrees, 2422 N. By our investigations, we can approximately prove the hip joint-centralizing force of the IT. By variation of the femoral neck angle and the position of the hip joint, we can predict the subligamentous force of the IT and the resulting force at the femoral head or at the acetabulum. The intraoperative measurement of the subligamentous forces of the IT is a good monitoring mechanism for the persistent hip-centralizing function of the IT in the course of hip joint replacement. The surgeon has the opportunity to check the stability of the hip joint after replacement. The finite element model gives the opportunity to check the divergent relative strength by variation of the femoral neck angle and the tension of the IT. In this way, the changes in the forces induced by a displacement osteotomy could be estimated preoperatively.

Abdominal musculature and the transversalis fascia: an anatomical viewpoint

This anatomical study investigated the connection of the muscles of the abdominal wall to the transversalis fascia in the groin. In six unfixed male corpses we prepared the single levels of the inguinal abdominal wall and examined their interrelationships. Of special interest were the direction of the force vectors determined by the direction of the muscular fibers in relation to the transversalis fascia. We found no confirmation of a direct connection between the muscles of the abdominal wall and the transversalis fascia in the inguinal region. No force vector of the different muscular layers points away from the triangle of Hesselbach. By contraction each muscle thus relaxes the transversalis fascia of the Hesselbach triangle.

Technical consideration for subxiphoidal incisional hernia repair

BACKGROUND

The main principle of incisional hernia repair with mesh augmentation is a wide overlap of at least 5 cm in all directions. This is complicated when cartilaginous or osseous structures border the fascial defect, most notably at the xiphoid after sternotomy or in large proximal incisional hernias.

METHOD

We performed an anatomic investigation of this "problematic" area with its different structures and layers that form the retroxiphoidal space.

RESULTS AND CONCLUSION

The posterior lamina of the rectus sheath inserts on the posterior side of the xiphoid. This lamina inhibits a sufficient mesh placement. By sharp dissection dorsal the xiphoid process, the posterior lamina of the rectus sheath can be detached. This way the retroxiphoidal space can be opened. Further development of this space can be made by blunt dissection. In some cases, with retroxiphoidal scar formation after sternotomy, a sharp dissection might be necessary. This enables a combined retromuscular-retroxiphoid mesh augmentation repair with a sufficient underlay of at least 5 cm, according to the principles of sublay technique.

The arterial vascularisation of the abdominal wall with special regard to the umbilicus

AIM

In order to prevent wound healing problems around the transposed umbilicus following abdominoplasty, we investigated the arterial vascularisation of the abdominal wall with special regard to the umbilicus. The aim was to optimise the planning of the umbilical stalk and flap design.

METHOD

The inferior and superior epigastric arteries of 12 cadavers (mean age 83 years) were injected with barium-sulphate, lead-mennige and gelatine. The abdominal walls were resected en bloc and X-ray photographs were taken by conventional and mammographic technique.

RESULTS

The radiographic examination showed that the main trunks of the epigastric vessels follow an "hour-glass" or "rhomboid" pattern around the centromedial umbilicus. Each main trunk splits into two obligate branches one medial and one lateral. The anastomosis between the inferior and superior epigastric artery is located above the umbilicus. The umbilicus is nourished by separate axial vessels originating from the inferior epigastric artery. It was also shown that the inferior intercostal arteries anastomose with the branches of the inferior and superior epigastric artery.

CONCLUSION

Dividing the abdominal wall into four quadrants around the central umbilicus, the lateral areas of the lower quadrants show the weakest vascularisation by the inferior epigastric artery. This fact may cause healing problems after surgery in this area. The axial vascularisation of the umbilicus makes any torsion or traction a potential hazard to the umbilical flap during abdominoplasty especially by re-siting the umbilicus. The anatomical study showed clearly the benefit of preparing a broad base fat layer with a generous diameter of incision line around the umbilicus.

Pitfalls in retromuscular mesh repair for incisional hernia: The importance of the ?fatty triangle?

Open retromuscular mesh repair has become a standard procedure in incisional hernia repair. This technique led to a significant decrease of recurrences. Recurrences after this technique typically occur at the upper mesh border and are a result of the technical complexity of reaching the postulated underlay of 5 cm in the region of the linea alba. We performed an anatomical study in human corpses to investigate the abdominal wall with its different structures, with emphasis on the overlap of the mesh under the linea alba. The overlap can be achieved by incision of the posterior lamina of the rectus sheath, on both sides close to the linea alba. The incision opens the preperitoneal space and appears in the shape of a "fatty triangle". The anterior lamina of the rectus sheath above the hernia defect remains intact and facilitates a sufficient thrust bearing for a retromuscular mesh implantation. Knowledge of the anatomy and preparation of the "fatty triangle" enables a mesh positioning according to the principles of retromuscular mesh repair.

[Foreign body-induced disruption of the gastrointestinal tract-anatomy of the ileocoecal opening]

INTRODUCTION

Over 75% of ingested foreign bodies pass the gastrointestinal tract without any complications. Blunt foreign bodies may lead to a disruption of the intestinal passage, mainly in the area of the ileocoecal opening. The size of the reported foreign bodies varies considerably. The aim of this study was the anatomic investigation to clarify the possible causes of obstruction and its influence on the diameter of the ileocoecal opening.

MATERIAL AND METHOD

We investigate anatomically and describe the ileocoecal opening on the basis of 27 specimens.

RESULTS

We found not a flap mechanism but a valve mechanism in the ileocoecal junction. The median diameter of the formalin-fixated specimens was 10.9 mm respectively 21.8 mm according to an assumed correction factor of 2. The cause for intestinal obstruction most probably is the ingestion of blunt, angular foreign bodies in the ostium ileale.

CONCLUSION

The intraindividual differences as well as the considerable size of foreign bodies that pass the ileoceocal opening support the hypothesis, that the complications described are more a consequence of an ingestion of blunt, cornered foreign bodies in the ostium ileale independent ofn the size of the ileocoecal opening itself.

Semicircular canal dehiscence: comparison of T2-weighted turbo spin-echo MRI and CT

We assessed the value of MRI for delineation of dehiscence of the superior or posterior semicircular canal, as compared with CT, the current standard study for this entity. We reviewed heavily T2-weighted fast spin-echo images and high-resolution CT of the temporal bones of 185 patients independently semicircular canal dehiscence and its extent. In 30 patients (19 men, 11 women) we identified dehiscence of the bone over the superior and/or posterior semicircular canal on MRI. In 27 of these cases CT also showed circumscribed bone defects. In one patient dehiscence of the superior semicircular canal was initially overlooked on MRI, but seen on CT. MRI imaging thus had a sensitivity of 96% and specificity of 98%. Knowledge of the appearances of this entity on MRI may contribute to early diagnosis in patients with vertigo due to semicircular canal dehiscence.

[Management of nasal fistulas with intracranial extension]

BACKGROUND

Medial nasal fistulas are rare congenital malformations that mostly become obvious by recurrent infections such as secretion from the fistula opening or swelling of the nasal tissues. In rare cases, these fistulas may extend intracranially with meningeal irritations.

PATIENT PRESENTATION

Three patients with medial nasal fistulas were operated during the last two years in our department. In two children, the fistulas ended at the glabella. In one older boy, the fistula revealed an intracranial extension. In the last case, a combined rhino- and neurosurgical approach was applied to perform a complete resection of the fistula.

DISCUSSION

During the second embryonic month of facial development, the medial nasal processes approach each other with a fusion of their epithelial covering that completely disappears during later stages. If parts of this epithelial fusion zone persist, epithelial remnants may develop into nasal fistulas or dermoids. The adequate therapy of these nasal malformations consists of a complete surgical removal.

Anheftungspunkte des Lig. longitudinale posterius und deren Bedeutung f�r Wirbelk�rperfrakturen

Spine fractures with damage of the posterior wall of the vertebra often can be anatomically reconstructed by indirect reduction. Whether the posterior longitudinal ligament (PLL) is responsible for the reduction is still subject to debate. The aim of our investigation was to ascertain the role of the PLL in closed reduction of spine fractures by identifying the bony attachment points of this ligament. We performed a gross anatomical dissection, a light- and polarized microscopic investigation on 22 human cadaverous thoracic and lumbar spines to determine the points of attachment of the PLL. We found two layers of the PLL. The superficial layer runs from the first thoracic down to the third lumbar vertebra with a width of 0.4-1.0 cm and from there descends as a thin rudiment to the sacrum. The deep layer shows a segmental rhomboid structure. Lateral fibers are attached to the annulus fibrosus and at the rim of the adjacent vertebrae. Medial fibers are attached additionally to the posterior wall of the vertebral bodies by bridging the foramina basivertebralia. Since these foramina become enlarged in the caudal parts of the vertebral column, the number of attachment points at the posterior wall of the vertebral bodies decreases caudally. Good results for reconstruction of the posterior wall in vertebral fractures of the thoracic and upper lumbar spine can be explained by the anatomical situation of the PLL and stress the important role of the PLL in indirect reduction of spine fractures.

[Partial intestinal obstruction after swallowing a self-expanding sponge for weight reduction]

HISTORY AND ADMISSION FINDINGS

A 21-year-old woman presented with predominantly right-sided cramp-like abdominal pain which had started the previous day. The abdomen was soft on palpation, the peristaltic sounds increased. Body temperature was normal.

INVESTIGATIONS

Routine laboratory tests were unremarkable, including white cell count (4.5 G/l). and C-reactive protein.

TREATMENT AND COURSE

She was admitted to hospital for observation. Because the symptoms persisted she underwent a right lower laparotomy because acute appendicitis was suspected. Intraperitoneal examination of the intestines revealed a soft, sponge-like foreign body just above the ileocecal valve. The overlying ileum was incised and a sponge removed. Postoperatively the patient reported having taken 4 capsules of CM3, a weight-reducing preparation, about 14 days ago. These capsules dissolve in the stomach and each releases a small sponge which expands and mechanically induces a feeling of satiation. The further course was unremarkable and she was discharged on the 8th postoperative day.

CONCLUSION

When producing weight-reducing preparations that act according to physico-mechanical principles, anatomical circumstances should be considered, and they should only be taken under medical supervision.

[Computer-assisted retrograde drilling of osteochondritic lesions of the talus with the help of fluoroscopic navigation]

AIM

Due to the narrow access to the talar dome and the proximity of osteochondritic lesions to the joint surface, the therapeutic retrograde drilling often requires multiple attempts and repeated intraoperative X-ray-control. The advantages of a fluoroscopy-based computer-assisted navigation system regarding efficient planning and easy performance of the ideal drill path are evaluated in respect to accuracy and radiation exposure, as well as to time requirements.

METHOD

A 5 mm spherical target was subcortically implanted in the medial aspect of the talar dome of 16 human cadaver specimens. Free-hand drilling was performed using the FluoroNav TM system in one group and conventional repetitive C-arm control in the other. The computed evaluation of the operative results was realized in a CT-generated 3D-model with the help of the DISOS planning and calculation program. The distance of the tip of the drill to the center of the lesion was measured, as well as X-ray exposure and total operating time.

RESULTS

The CAS procedure missed the lesion only once. The mean deviation of the computer-guided drill path was measured to be 2 mm, whereas the conventional method led to a mean distance of 5 mm from the target. Conventional drilling failed to reach the target in 5 cases, violating the articular cartilage twice. Navigation reduced the traditionally required multiple attempts of the intervention to just one drill canal and reduced radiation time to 25 %. Despite the increased technical preparation required, the navigated procedure only exceeded the conventional operating time by 2 minutes.

CONCLUSION

Thanks to the significantly increased accuracy, fluoroscopic navigation offers a high degree of safety and efficacy for this minimally invasive procedure. The operation can easily be performed successfully causing only minimal collateral damage to the bone, preserving the joint surface. The inherent risks of the retrograde drilling of osteochondritic lesions are lower with navigation, while the radiation exposure of the patient and the staff is significantly reduced.

Posterior semicircular canal dehiscence: a morphologic cause of vertigo similar to superior semicircular canal dehiscence

The aim of this study was to assess imaging findings of posterior semicircular dehiscence on computed tomography and to evaluate incidence of posterior and superior semicircular canal dehiscence in patients presenting with vertigo, sensorineuronal hearing loss or in a control group without symptoms related to the inner ear. Computed tomography was performed in 507 patients presenting either with vertigo ( n=128; 23 of these patients suffered also from sensorineuronal hearing loss), other symptoms related to the inner ear, such as hearing loss or tinnitus ( n=183) or symptoms unrelated to the labyrinth ( n=196). All images were reviewed for presence of dehiscence of the bone, overlying the semicircular canals. Twenty-nine patients had superior semicircular canal dehiscence. Of these patients, 83% presented with vertigo, 10% with hearing loss or tinnitus and the remaining 7% with symptoms unrelated to the inner ear. In 23 patients dehiscence of the posterior semicircular canal was encountered. Of these patients, 86% presented with vertigo, 9% with hearing loss or tinnitus and 5% with symptoms unrelated to the inner ear. Defects of the bony overly are found at the posterior semicircular canal, in addition to the recently introduced superior canal dehiscence syndrome. Significant prevalence of vertigo in these patients suggests that posterior semicircular canal dehiscence can cause vertigo, similar to superior semicircular canal dehiscence.

[Accuracy of fluoroscopically navigated drilling procedures at the hip]

AIM

Many orthopaedic procedures require an accurate drilling in bone. The outcome is frequently dependent on the geometric accuracy of this surgical step. The precision of such a procedure can be improved with the help of fluoroscopic navigation. Reliability, accuracy and benefit of this new method for the patient, as well as for the surgical staff, need to be analysed.

METHOD

In a standardised in vitro trial, the drilling of a 5 mm spherical lesion implanted in an artificial femoral head was performed using a navigated drill-guide and a navigated drill. In groups A and B, the distance of the tip of the drill to the center of the lesion was analysed in a 3D CT-generated model and in macroscopic cross section. Additionally, in group B the actual direction of the drill canal was measured.

RESULTS

The mean distance in group A was measured to be 1 mm, with all results ranging between 0 and 2.5 mm. In group B the planned direction of the canal was reproduced with a deviation of 0 degrees to 7 degrees, the target only being missed by a mean distance of 2.5 mm and a maximum of 3.5 mm. Compared to the macroscopic and 3D-CT findings, the correlation of the data calculated by the navigation system was accurate up to a difference of 4 degrees or 2 mm.

CONCLUSION

The fluoroscopically assisted freehand navigation used during the drilling of bone led to a high accuracy of three-dimensional tip placement while reducing radiation exposure to a minimum. It represents a promising and efficient application for a variety of procedures in orthopaedic surgery.

The petromastoid canal on computed tomography

The objective was to assess visibility and anatomy of the petromastoid canal in high-resolution CT. Computed tomography images of 188 patients were reviewed for delineation of the petromastoid canal. This bony canal connects the mastoid antrum with the cranial cavity and houses the subarcuate artery and vein. The diameter, obtained in the middle portion of the canal, was compared with the diameter of the vestibular and cochlear aqueduct in all patients, and absolute values measured in 20 cases. Collimation was 1 mm in 164 and 2 mm in 24 examinations. Additionally, temporal bone of a cadaver was imaged and microdissected. The petromastoid canal was identified bilaterally in all 164 scans that were obtained with a slice thickness of 1 mm. In 5 of the 24 patients imaged with a collimation of 2 mm, the canal was not visible, most probably due to partial-volume effects. The petromastoid canal had the same diameter as the cochlear aqueduct in 42/44 (right/left), exceeded it in 66/61 and was smaller in 75/78 cases. In comparison to the vestibular aqueduct it had an equal diameter in 38/41 (right/left), exceeded it in 63/61, and was rated as smaller in 82/81 temporal bones. Diameters for the canals were: petromastoid canal 0.51+/-0.04 mm; cochlear aqueduct 0.57+/-0.03; and vestibular aqueduct 0.63+/-0.06 mm. Microdissection of the specimen revealed the entire course of the canal and demonstrated a similar appearance of the structure as in the images. The petromastoid canal can easily be identified on high-resolution, thin-slice CT images. Knowledge of the anatomy of this bony canal prevents misinterpretation as pathological structure, such as fracture line, which might occur if this structure is not known.

A simple new method to calculate small intestine absorptive surface in the rat

The rat is an established model for studying intestinal adaptations following abdominal surgery. In the study of functional and morphological adaptations of the small intestine, it is helpful to estimate the mucosal surface area. In order to simplify measurements and calculation we developed a new mathematical model for calculation of the mucosal surface area on histological sections. In contrast to other methods, it requires only cross-sections of small intestine and includes the measurement of only three histological parameters: length and width of villus and width of crypt. The new approach was compared with the most commonly used procedures, the Harris and the Fisher-Parsons methods, under experimental conditions. An animal study including single-pass perfusion, fixation, staining and subsequent histomorphometry of jejunum and ileum using these different methods was performed. The new method showed the least work and presented no significant differences compared with the precise Harris method. In conclusion, the method described is an adequate tool to estimate the mucosal surface area with less work and with comparable results to established methods. The less-complex method may be a valuable tool in experimental research of small intestine adaptations in rats.

[Aetiology of Angiofibromas: Reflection on their Specific Vascular Component]

BACKGROUND

Even though numerous theories have speculated either on the vascular or fibrous tumour component as tissue of origin, aetiology of angiofibroma still remain unclear. Histological investigations recently led Beham and coworkers to the assumption that angiofibromas have to be considered as vascular malformations.

METHODS

After giving a literature review of the various theories on tumour origin the proposal to consider angiofibromas as vascular malformations is discussed on an embryological base. Taking typical clinical features of the tumour and knowledge of vasculogenesis into account a new explanation for origin of the vascular tumour component is presented.

RESULTS

The vascular component of angiofibromas can be explained embryologically due to incomplete regression of the first branchial arch artery (vascular atavism). This vessel arises regularly between embryological day 22 and 24 and recedes during regular development completely until delivery via temporary formation of a vascular plexus. In the late stages of embryological development remnants of the plexus are found at the area of the sphenopalatine foramen, the typical site of angiofibroma origin. Incomplete regression of the vascular plexus of the former first branchial arch artery may form the vascular component of an angiofibroma arising due to growth stimulation at the time of adolescents.

CONCLUSIONS

Incomplete regression of the first branchial arch artery presenting an atavism is suited to explain the vascular tumour component of angiofibromas considering main tumour characteristics (origin in the posterior nasal cavity close to the sphenopalatine foramen, main blood supply from the maxillary artery with possible feeders arising from the internal carotid artery). Our embryological contributions support to define angiofibromas as vascular malformations.

[Metastases to the paranasal sinuses: case report and review of the literature]

The case of an 87-year old man with widespread prostatic cancer is reported. During the autopsy macroscopically visible metastases were found within the frontal sinuses. These tumor masses destroyed the posterior osseous wall of the frontal sinus and formed polypoid bulging masses. In contrast to the macroscopically unaffected mucous membrane of the sphenoid sinus the maceration specimen of the skull base demonstrated a spongious-mossy, osteoplastic metastasis, lining the sphenoid sinus like a tapestry. This affection started from an exhaustive osteoplastic metastasis within the clivus. No metastases could be found in both antrums or the ethmoids. Retrospectively no symptoms from the paranasal sinuses could be eruated, only occasional pain of the frontal bone. The review of the world literature with 123 reports revealed 169 cases. Renal cell carcinomas most frequently metastasize into the paranasal sinuses (67 cases), followed by bronchogenic carcinomas (15 cases). Thyroid cancers and cancers of the mammary gland are responsible for 13 respectively 14 cases. The prostate also adds 12 cases. The paranasal sinuses are affected in diminishing frequency: maxillary sinus (55 cases), sphenoid sinus (37 cases), ethmoidal cells (23 cases) and frontal sinus (15 cases). In 38 cases exhaustive metastases affecting two or more paranasal sinuses are reported. The statement of literature, that metastases affecting the paranasal sinuses are much more frequent than reported, cannot be supported by our study, because the intensive autoptic investigation of 50 skulls of patients suffering from widespread cancers revealed no further cases of metastatic processes of the paranasal sinuses.

[Effect of femoral intramedullary irrigation on periprosthetic cement distribution: jet lavage versus syringe lavage]

INTRODUCTION

The purpose of this experimental study was to determine quantitatively the cement penetration into periprosthetic femoral bone by Icomparing the use of jet-lavage with the conventional syringe irrigation.

METHODS

10 pairs of fresh-frozen human cadaver femora were used for cemented stem implantation, The left femora were irrigated with a syringe device, the right femora with a jet-lavage system. After implantation, all femora were cut into 5-mm slices from proximal to distal with a diamond saw. The scanned slices were analysed using an image processing system which provided a discrimination between implant, cement, and bone as well as an exact determination of the cement area.

RESULTS

In all 10 femora, a recognizable improvement of the cement penetration into the periprosthetic bone was demonstrated using the jet-lavage. In the proximal part, the mean cement penetration was 8.6% higher in the jet-lavage group than in the syringe device group. An equivalent tendency towards the jet-lavage pretreated femora was seen in the middle part with 8.7% on average mean and in the distal part with 6.4% on average. Also, when subdividing the periprosthetic area into 4 quadrants, a significant improvement of the cement penetration was found with the exception of the ventro-medial region.

CONCLUSION

Cement distribution and penetration is improved using the jet-lavage technique for cleaning the medullary canal of the femur. Therefore, the jet-lavage should be used as a standard procedure in clinical cementing techniques.