Elasticity of the anterior abdominal wall and impact for reparation of incisional hernias using mesh implants

Mesh implantation to repair incisional hernia involves extensive disturbance of the integrity of the abdominal wall. To define the physiological requirements, we measured the elasticity of the abdominal wall of 14 anatomic samples. The complete abdominal wall was excised and stretched at a strain of 0-24 N in horizontal, vertical and oblique (upper and lower abdomen) directions. The resulting mean distension at 16 N was in the range between 11% and 32% for all directions. Furthermore, we found significant differences between tissue samples from male and female subjects, as well as considerable inter-individual differences in each group. Textile analysis of common mesh materials at 16 N showed elasticities in the range of 4%-16%. Comparing the textile characteristics with the physiological elasticity revealed inadequate properties in at least some of the mesh materials. Our findings indicate that the flexibility of the abdominal wall must be more or less restricted by extensive implantation of large meshes and recurrences may possibly be provoked at the margins of implanted materials.

[Panorama ultrasonography of the abdominal wall for delineation of the anatomy and diagnosis of pathological findings]

PURPOSE

To assess extended field-of-view sonography for delineation of the anatomic structures of the abdominal wall and for the diagnosis of hernia.

MATERIAL AND METHODS

In 34 cases (24 probands, 10 patients with abdominal wall defects) extended field-of-view sonography of the abdominal wall was performed with a 7.5 MHz transducer. Dynamic alignment of real-time images allows for depiction of regions of up to 60 cm in a single extended field-of-view image. A standardized axial image was obtained above and below the arcuate line and at the level of the defect, respectively. All images were evaluated by two blinded readers regarding the visibility of the anatomic structures and the delineation and extent of pathological changes.

RESULTS

The abdominal wall was delineated with extended field-of-view sonography in all patients with a good image quality. The linea alba, the rectus muscle and the three lateral abdominal muscles, the rectus sheath, the peritoneum, and the subcutaneous fatty tissue were visible. In the patients with abdominal wall defects, the hernial sac with its contents, the extension of the defect, and the surrounding structures were clearly delineated.

CONCLUSION

Extended field-of-view sonography allows for easily surveyed and reproducible documentation of the ultrasound examination of the abdominal wall. It is especially useful for the preoperative planning in patients with abdominal wall defects.

Correction of kyphotic deformity before and after transection of the anterior longitudinal ligament--a cadaver study

With a custom-made measuring unit, two separate experiments, involving six and five cadaveric torsos with intact rib cages and sternums, respectively, were carried out to determine the effect of the transection of the anterior longitudinal ligament with and without osteodiscectomy and its influence on the thoracic kyphosis. The open or thoracoscopically assisted anterior release, as part of the operative treatment of scoliosis or kyphosis, usually consists of a transection of the anterior longitudinal ligament (ALL) and an additional discectomy. A complete osteodiscectomy, however, is not always possible with a minimally invasive approach. As part of our biomechanical research, we attempted to quantify the amount of correction achievable with a defined force prior to and following the isolated transection of the anterior longitudinal ligament. The aim of the study was to clarify whether or not an isolated transection of the anterior longitudinal ligament is sufficient to obtain an adequate anterior release of the spine. In the surgical treatment of kyphotic deformities, anterior release of the spine is performed in the form of a transection of the ALL and discectomy. Recently, video-assisted thoracic surgery has become increasingly popular in spine surgery. As part of this change in surgical technique, the question has arisen as to what extent an isolated transection of the ALL provides an adequate release of the thoracic spine. Eleven human spines were retrieved from fresh cadavers, dissected, and attached to a specially constructed apparatus. The spine was attached to the construct at the twelfth vertebral body. C6 and C7 were fixed in synthetic resin. We installed the instruments in such a manner as to reproducibly apply a torsional moment of 10 Nm to the spine. Motion was only permitted in the sagittal plane. Segmental transections of the ALL were carried out from T3 to T7. For comparison, the sagittal Cobb angle was also documented following an anterior release combined with an osteodiscectomy. With the isolated transection of the ALL, an average correction of the sagittal Cobb angle of 4 degrees in each functional spinal motion segment was recorded. In comparison, the additional osteodiscectomy led to a further average increase of only 2 degrees per level. The measurements performed on human cadavers showed that the isolated transection of the ALL leads to a sufficient anterior release of the thoracic spine, allowing a correction of the kyphotic deformity. The release with a concomitant osteodiscectomy represents a more time-consuming and more invasive procedure resulting in only a slightly greater amelioration of the sagittal Cobb angle, while being associated with a greater patient morbidity.

Sternberg's canal--cause of congenital sphenoidal meningocele

We present a case of a 29-year-old female complaining of right-sided watery nasal discharge. Radiological investigations identified an intrasphenoidal meningocele. The origin of the meningocele was pinpointed to the right parasellar region and was confirmed surgically. The parasellar bony defect appeared to be due to persistence of the lateral craniopharyngeal canal (Sternberg's canal). Therefore, we assume a congenital origin for the intrasphenoidal meningocele found in the patient. Acquired bony defects of the sphenoid sinus are unlikely at the fusion planes of the different sphenoid bone components. Knowledge of the complex ontogeny of the sphenoid bone is an important key to differentiating between congenital and acquired sphenoid sinus meningoceles.

Complications of Chiari and Salter osteotomies: a cadaver study

Previous investigations of the Chiari and Salter osteotomies showed that intraoperative vessel and nerve injuries are described repeatedly in the case of both pelvic osteotomies. The aim of our investigations was the exposure of each operation step in anatomic specimens to show the anatomic landmarks and potential risks. We performed nine Chiari osteotomies and five Salter osteotomies on formalin-fixed cadavers. The operation steps were made consecutively to assess the risks to the vessels and nerves as well as the determination of anatomically important reference points. In both procedures an injury of the lateral femoral cutaneous nerve at the anterior access route is feasible. By ensuring that the skin including the lateral femoral cutaneous nerve is pulled medially, injury can be avoided. Additionally, too long retraction of the tensor fasciae latae muscle injures its nutrient vessels. An inadequate subperiosteal approach during the pull on the Hohmann's retractor leads to crushing and irritation of the sciatic nerve. Moreover, there is a risk that the superior gluteal nerve as well as the superior gluteal artery may be injured. An inadequate subperiosteal application of the medial Hohmann's retractor can endanger the obturator nerve. In the Chiari osteotomy there is a risk of injury to the articular branch of the superior gluteal nerve, which supplies parts of the ventral hip joint capsule. By inserting the K-wire too far medially the internal oblique muscle is endangered. Too prolonged retraction of the iliopsoas muscle in a Salter osteotomy can lead to compression of the femoral nerve. The form of the osteotomy has an influence on the stability of the hip joint in the course of exposure of the hip joint. On account of the narrow spatial connection between the anatomic pathways and the osteotomy area, strict subperiosteal dissection and careful use of the retractor are essential to avoid nerve and vessel injuries.

Collagen fibers in linea alba and rectus sheaths

BACKGROUND

After the description of a general scheme of the architecture of collagen fibers in linea alba and rectus sheaths, variability and differences of fiber architectures were analyzed to describe their functional role.

MATERIALS AND METHODS

Using confocal laser scanning microscopy the diameter of each layer of fibril bundles was measured in linea alba and rectus sheaths of 12 human cadavers, and each fibril bundle was classified according to its orientation (oblique I and II, transverse).

RESULTS

The mean diameter of fibril bundles in the supraumbilical region of the linea alba was smaller than in the infraumbilical region, and in the supraumbilical region the thickness of the linea alba was smaller than in the infraumbilical region. Analyzing sex-dependent differences in the fiber architecture of the linea alba, a larger amount of transverse fibers relative to oblique fibers were found in females in infraumbilical regions. The thickness of the infraumbilical linea alba was smaller in females than in males, while its width was larger.

CONCLUSIONS

There exist gender differences in the architecture of the linea alba. However, whether these morphological differences demonstrate the adaptability of this fiber architecture to biomechanical stress in raised intraabdominal pressure in pregnancy remains to be proven. The transverse fibers act as a counterpart to the intraabdominal pressure whereas the oblique fibers are involved mainly in movements of the trunk.

Thoracoscopically assisted ligamentous release of the thoracic spine: a cadaver study

The surgical treatment of thoracic kyphosis frequently requires an anterior release, which can be carried out by an open or endoscopic technique. This study concerns the reference points which are essential from the anatomic view for minimizing the operative risks. Furthermore we wanted to find the most convenient video-assisted thoracoscopic surgery (VATS) technique for transection of the anterior longitudinal ligament (ALL). Transection of the ALL, as well as discectomy, was performed using this technique. The extensive anatomic dissection of 12 fresh cadavers was performed to define possible technical errors and surgical complications. The development of new instruments has made the VATS approach to the ALL a viable alternative to open procedures. With the help of a standardized technique, the isolated thoracoscopic ligamentous transection required less time than the comparable open procedure. The anatomic study showed, that in no case was a ligation of the intercostal or segmental vessels necessary as part of the approach to the spine, once an adequate mobilization of the esophagus and azygos vein had been carried out. The risk of an ischemic lesion of the spinal cord was thereby reduced. The thoracoscopic, limited anterior release consisting of a multilevel transection of the ALL proved to be a rapid and reliable procedure. Our anatomic studies provides suitable the reference points.

Collagen fibers in linea alba and rectus sheaths. I. General scheme and morphological aspects

BACKGROUND

The anatomy of the anterior abdominal wall plays a most significant role in surgery. Thus the three-dimensional architecture of the collagen fibers in linea alba and rectus sheaths was investigated in 12 human cadavers.

MATERIAL AND METHODS

The linea alba was divided into 14 different anatomical segments in the craniocaudal direction. Two-hundred-micrometer-thick, eosin-stained sections from these segments were analyzed by confocal laser scanning microscopy. In this way the direction of the collagen fibers was estimated in the midline of the linea alba and in the medial parts of the rectus sheaths. Width and thickness of the linea alba and thickness of the rectus sheaths were measured.

RESULTS

In the ventral rectus sheath essentially oblique fibril bundles intermingle with each other, while the dorsal rectus sheath consists chiefly of transverse fibril bundles. In the linea alba three different zones of fiber orientation follow each other from ventral to dorsal: The lamina fibrae obliquae consists of intermingling oblique fibers. The lamina fibrae transversae contains mainly transverse fibril bundles, while an inconstant, small lamina fibrae irregularium is composed of oblique fibers. Different regions can be distinguished in the craniocaudal course of the linea alba: supraumbilical part, umbilical part, transition zone, and infraarcuate part.

CONCLUSIONS

A new model of fiber architecture of the linea alba was developed that describes the fiber architecture as a three-dimensional, highly structured meshwork of collagen fibers. In contrast to former models, no separate lines of decussation of the fibers could be found.

Computer-assisted orthopedic surgery with individual templates and comparison to conventional operation method

STUDY DESIGN

Comparison was made of the accuracy of a pedicle bore performed by conventional technique and by using an individual template in the lumbar spine of cadavers.

OBJECTIVES

The fixation of pedicle screws necessitates a high amount of surgical skill and experience to avoid lesions of nerves and vessels. By using individual templates in a cadaver study the goal was to prove the accuracy and efficiency of this less-invasive image-guided surgery in comparison with the conventional technique by fluoroscopy and computed tomographic (CT) scan.

SUMMARY OF BACKGROUND DATA

Based on three-dimensional models generated from CT scans of the lumbar spine, precise preoperative planning of the position and trajectory of pedicle screws is possible. In comparison with other means of computer-assisted spine surgery with navigation systems, in which a time-consuming intraoperative matching of the bone surface structure is necessary, the use of individual templates enables the surgeon to reduce the operation time considerably.

METHODS

Individual templates are customized on the basis of three-dimensional reconstructions of the bone structures extracted from CT image data and depending on the individual preoperative surgical planning, which uses the desktop image processing system for orthopedic surgery (DISOS). A desktop-computer-controlled milling device is used as a three-dimensional printer to automatically mold the shape of small reference areas of the bone surface into the body of the template. Postoperative CT scans were obtained and the accuracy of the pedicle bore rated by two independent observers.

RESULTS

The preparation time with the individual template lasted slightly longer than with the conventional operation technique (555 seconds and 482 seconds, respectively). Fluoroscopic study took a mean time of 31.5 seconds, with the conventional operation technique and 5.5 seconds with the individual template. The assessment of the postoperative CT scans demonstrated a higher accuracy of the pedicle bore with the individual template.

CONCLUSIONS

This cadaveric study has shown that overall operation time including the fluoroscopy time can be shortened by using the individual template for the pedicle bore. The individual template is an alternative to the computer-assisted navigation systems with a good cost-performance ratio without excessive technical workload on the physicians or the surgical personnel. Further investigations must be conducted to validate the clinical applicability of this system.

[Preserving autonomic nerves in rectal surgery. Results of surgical preparation on human cadavers with fixed pelvic sections]

INTRODUCTION

Preservation of sexual function and voiding capacity after rectal cancer surgery has increased after adopting the technique of nerve-sparing dissection and total mesorectal excision. Still the rate of sexual and urinary dysfunction ranges between 25 and 67%. The precise locations where nerve damage occurs have not been looked at systematically.

MATERIAL AND METHODS

In ten human corpses and two formalin-fixed human pelvises the autonomous pelvic nerves were isolated. Their relation according to surgical mobilization of the rectum were photodocumented.

RESULTS

Pelvic autonomous nerves are clearly defined structures with only minor interindividual variability. The inferior mesenteric plexus forms a dense network around the inferior mesenteric artery (AMI) to a distance of 5 cm from the aorta. The distance between the lateral rectum and the pelvic plexus is only 2-3 mm. The anterior rectum is almost directly adherent to the neurovascular bundle, separated only by Denonvillier's fascia. The parasympathetic branches of the sacral segments S2-S5 cannot be isolated using the standard surgical approach.

CONCLUSION

(1) The nomenclature of fascias and the course of the autonomous pelvic nerves is not clearly defined in the literature; (2) a high tie of the AMI leads to damage of the sympathetic nerves; (3) the narrow space between the anterior and lateral rectum makes sharp dissection under direct vision necessary; (4) fascias and nerves can be used as guiding structures during mobilization; (5) a preservation of selected parasympathetic roots in the small pelvis is not feasible using the standard surgical approach.

[Nuclear magnetic resonance tomography imaging and functional diagnosis of the eustachian auditory tube]

PURPOSE

To develop and evaluate a protocol for the anatomic depiction and functional testing of the auditory tube with the use of MR imaging.

METHODS

Eleven volunteers were included into this study. For the morphological assessment, the imaging protocol included axial and coronal T2-weighted turbo-spin echo sequences (TR/TE = 3194/100 ms) and a T1-weighted gradient echo sequence (TR/TE = 42/4.6 ms). For the functional test a dynamic turbo-gradient echo sequence (TFE) with spectral fat suppression (TR/TE = 15/6.2 ms; 4 sec) was obtained using the single slice technique before and during the Valsalva manoeuvre.

RESULTS

With multi-slice sequences, the osseous part of the auditory tube, the tubal cartilage (middle and lateral lamina), the ciliated epithelium, Ostmann's adipose body and the levator and tensor veli palatini muscles were delineated in all cases. During the Valsalva test, opening of the auditory tube was demonstrated in 20 of the 22 investigated sides using the dynamic TFE single slice sequence.

CONCLUSIONS

The introduced MRI protocol allow visualization of the opening of the auditory tube and provides detailed anatomical information of the nasopharynx. Comprehensive morphological and functional evaluation of the auditory tube becomes possible within a single examination'.

Anatomical basics, variations, and degenerative changes of the shoulder joint and shoulder girdle

This paper summarizes the anatomical basics of the shoulder, their variations, and precise definitions, including differential diagnoses. It also describes the characteristic degenerative changes caused by aging. A typical variation (7-15%) is the os acromiale, which forms the triangular epiphysis of the scapular spine. This abnormality must be differentiated from a fracture of the acromion or a pseudarthrosis. Because ossification of the acromion is complete after age 25, the os acromiale should be diagnosed only after this age. The shape of the acromion is a further important feature. In a recent anatomical study, the following frequencies of the Bigliani-types of the acromial shape were anatomically determined - type 1 (flat), 10.2% and type 2 (curved), 89.8%. Type 3 (hooked) was not observed, which indicates that this type is probably a misinterpretation of the so-called acromial spur. Minor dehiscences and perforations in the infraspinate or supraspinate fossa should not be confused with malignant osteolyses. The scapula has three ligaments of its own, (1) the coracoacromial ligament and its osseous fixations form an osteofibrous arch above the shoulder joint, which plays a part in impingement syndrome; (2) the superior transverse scapular ligament or its ossified correlate arches the scapular incisure and can cause a typical compression syndrome of the suprascapular nerve; (3) the inferior transverse scapular ligament is of no great clinical importance. Two intraarticular structures (glenoid labrum and tendon of the long bicipital head) must be mentioned. The glenoid labrum consists of dense connective tissue and surrounds the margin of the glenoid cavity. Two areas exhibit specialized conditions, cranial at the supraglenoid tubercle an intimate relationship exists to the tendon of the long bicipital head and in about 55% of cases, the labrum is stretched over the glenoid rim at the ventral side. At the area of the biceps-tendon-labrum complex, so-called SLAP-lesions may occur and at the glenoid rim, where the labrum is often not fixed to the bony margin, avulsions of the labrum may occur. This well-established anatomical condition must not be mistaken for a manifest Bankart-lesion. The glenohumeral ligaments, which are located in the ventral articular capsule, have a stabilizing function for the ventral part of the glenoid labrum. The glenohumeral ligaments lift the articular lip where it crosses the glenoid notch. This 'labrum-lift effect' supports the stabilizing features of the articular lip and the glenohumeral ligaments. The rotator cuff is composed of the tendons of the teres minor, infraspinatus, supraspinatus, and subscapularis muscles. This cuff has a poorly vascularized area, due to mechanical conditions, about 1.5 cm from the major tubercle, which causes degenerative changes and eventually may lead to ruptures. Results of the impingement-syndrome and the osteoarthrotic changes of the shoulder and acromioclavicular joint are also presented and discussed. Finally, the coracoclavicular joint, which probably represents no congenital entity but appears due to a changed, lowered position of the shoulder girdle, is discussed. The paper also presents instructive figures of anatomical preparations that can be used to make more precise radiological and differential diagnoses. All preparations were done by the author and are part of a series of more than 300 preparations of the shoulder joint and girdle.

Surgical embryology and anatomy of the diaphragm with surgical applications

This article reviews the development, surgical anatomy, and teratology of the diaphragm, and discusses the diagnostic procedures, surgical therapy, and prognosis of congenital disturbances. Special attention is paid to the traumatic rupture of the diaphragm, concerning incidence, cause, diagnosis, prognosis, and surgical repair.

Appendix and cecum. Embryology, anatomy, and surgical applications

Surgeons should be familiar with surgery of the cecum and appendix because the diseases of this region, especially appendicitis, are the most common indications for surgical exploration. Usually, diagnosis of appendicitis and appendectomy are not difficult, but atypical location of the appendix or other anatomic anomalies can make the diagnosis of appendicitis and appendectomy difficult. In cases of atypical anatomy or diffuse clinical picture, especially in young adults or elderly patients, the spectrum of embryologic and anatomic anomalies must be kept in mind to make the correct treatment decision for individual patients. If doubt persists, explorative laparotomy must be performed to avoid overlooking rare, acute, intra-abdominal abnormalities.

[Disruption of the arteria nutricia tibiae by reamed and unreamed intramedullary nailing. Study of the vascular architecture of the human tibial intramedullary cavity]

AIM

By reason of the pseudarthrotic healing of fractures due to vascular complications after reamed and unreamed intramedullary nailing, the intraosseous course and branching of the tibial nutrient artery and its impairment by nailing procedures needs an actual analysis.

METHOD

The nutrient vessel of 24 tibiae taken from fresh corpses were prepared by injection of Technovit and lead oxide. After this procedure the medullary cavities of 12 bones were opened by a frontal cut. These specimens were subjected to routine maceration. The other 12 tibiae were naed with the unreamed (6) and the reamed nailing (6) techniques. X-rays were also taken routinely.

RESULTS

After penetration of the tibial compact bone the main trunk of the nutrient vessel runs through a perforated osseous tunnel (pars tecta arteriae nutriciae tibiae). At its end the vessel divides into a descending branch (obligate) and two ascending branches (facultative). The descending branch lies near to the centromedial region of the medullary cavity which is termed as the pars liberal arteriae nutriciae tibiae. All branches pass through supporting horizontal osseous lamellas. Due to this topography the reamed nailing technique destroyed the nutrient vessel completely in all specimens. In contrast to this observation the unreamed nailing destroyed the vessel completely only in 1 (16.7%) and partially in 3 (50%) bones; 2 (33.3%) specimens exhibited no destruction of the vessel.

CONCLUSION

The unreamed as well as the reamed nailing technique can destroy the intramedullary course of the tibial nutrient artery. Fractures as well as displacement osteotomies or corticotomies are able to diminish the medullary blood supply seriously, if they are localised within the area of the tactic an of the tibial nutrient artery.

Conductive hearing loss in Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome is a rare genetic overgrowth syndrome presenting with organomegaly, abdominal wall defects, macroglossia, and postnatal hypoglycemia. Head and neck manifestations of this abnormality include flame nevus of the forehead and characteristic sulci of the ear lobe. We present a 7-year-old child with Beckwith-Wiedemann syndrome and a rare finding of conductive hearing loss on both sides due to congenital malleus and stapedial fixation. Small fenestra stapedotomy and mobilization of malleus fixation in the epitympanum improved the child's hearing. The bony fixation of the malleus and stapes is explained as atavism of the processus anterior mallei and peripheral lamina stapedialis in embryological development.

Extra- and intracellular accumulation of ultrasmall superparamagnetic iron oxides (USPIO) in experimentally induced abscesses of the peripheral soft tissues and their effects on magnetic resonance imaging

The effects of ultrasmall superparamagnetic iron oxide (USPIO) particles on magnetic resonance imaging (MRI) were studied in an animal abscess model and the findings compared with microscopic sections of the abscesses. Staphylogenic abscesses of the right hind leg were induced in six Sprague-Dawley rats. The USPIO particles consisted of polyethylene-glycol-coated Fe3O4 with a mean size of 26 nm and were injected intravenously (i.v.), with three animals receiving a dose of 50 micromol/kg and three animals a dose of 150 micromol/kg. Before and immediately after i.v. administration of the particles, MR data were acquired with fast gradient-echo technique FLASH sequences applied over a period of 60 min. The Fe3O4-induced signal changes were registered in regions of interest (ROIs) placed over the margin and center of the abscess, over the perifocal granulation tissue and over corresponding sites of the contralateral healthy muscle. Microscopic sections were prepared using the conventional paraffin technique and, in part, a kryohistologic method before staining of the specimen with hematoxylin and Berlin-blue reaction. In addition to the mostly perfusion dependent loss of signal intensity within 8 s after injection, a signal reduction, which could be rather pronounced, was observed in the abscess margin and perifocal granulation tissue, with the underlying mechanism mainly attributed to extravasation and predominantly extracellular deposition of Fe3O4.

CONCLUSION

The USPIO particles used in this study lead to a prolonged demarcation of abscesses in the peripheral soft tissues due to particle extravasation and accumulation in the periphery of the abscesses. Besides the known accumulation of already characterized USPIO in the RES of liver, spleen and lymph nodes the study could demonstrate ultrasmall iron oxide deposition (BY 818) in abscesses of the peripheral soft tissue.

Errors of computer-assisted migration analysis in conventional radiographs of femoral hip implants--an experimental study

Several methods have been described in the literature in order to analyze migration of femoral hip implants in conventional radiographs. However, no measurements were done regarding the potential errors inherent in such unstandardized radiographs of daily routine. In order to quantify this lack of reproducibility, we carried out experimental examinations with radiographs of a hip revision prosthesis, where different variables of technical X-ray conditions and femoral positions were changed. All radiographs were analyzed with a computer-assisted processing system by different procedures. At first, the radiographs were calibrated geometrically. Then, particular reference distances between defined points of the implant and cortical bone structures were analyzed quantitatively. The error of the axial migration analysis was up to 11.11 mm concerning different femoral positions, up to 8.29 mm in the case of different source-to-film distances and up to 2.21 mm due to different lateral localizations of the central X-ray focus. Significant errors for the migration analysis in the transverse and rotational planes were only found under conditions of varying the femoral position, and not under different technical X-ray conditions. From these experimental results, we derived the following criteria to minimize failure in a quantitative radiographic migration analysis: (1) the patient's leg has to be placed into an antirotation device to ensure identical object position; (2) the same source-to-film distance has to be used; (3) the central X-ray focus has to be localized on the center of the film-cassette; (4) film-screen systems should be of the same type and size; (5) the object has to be placed in the same position as in previous radiographs. As a conclusion, only if these standardization criteria are respected in the daily routine of conventional radiographs will an effective and meaningful use of migration analysis systems be possible to prove or to exclude mechanical failure of femoral hip implants in prospective longitudinal follow-up series.

An unusual cavity within the styloid process

A rare case of an unusual sinus within the styloid process is described. The radiological appearance of this malformation is presented with CT-scans and a hypothesis for its development is presented. The malformation is designated as "Recessus processus styloidei" and this entity is considered to be a dysgenesis of the second branchial arch.

Unusual sinus of the styloid process

The case of a 50-year-old man with an unusual sinus of the styloid process is presented. This anomaly caused recurrent otorrhea and repeated neck inflammation. The sinus was identified in the upper part of the styloid process and was resected completely as definitive treatment. Since the styloid process is formed by mesenchymal tissue of the second branchial arch, lack of chondrification and ossification was presumed to be the cause of the sinus found in the patient. In case of direct communication between the styloid process cavity and the middle ear space the term "styloid process recess" is suggested. This recess can act as a possible source for recurrent middle ear infections and neck inflammations.

Detection of an occult transclival cerebrospinal fluid fistula by CT and MRI

We describe an unusual occult transclival cerebrospinal fluid (CSF) fistula to the sphenoid sinus demonstrated by MRI. CT was performed because of a posterior cerebral infarct caused by cardiac arrhythmia. Axial sections showed fluid in the sphenoid sinus. High-resolution scans revealed a bony defect 3 mm in diameter of the posterior wall of the sphenoid sinus, and MRI showed a transclival CSF fistula. This occult lesion was confirmed by surgery and duraplasty was successfully performed via an endonasal approach.

[Sensory innervation of the hip joint capsule in dogs]

The innervation of the canine hip joint has become increasingly important in the treatment of hip dysplasia and hip arthrosis, since investigations proved that simple removal of periosteum around attachment of hip joint capsule, called denervation results in an instant analgesia and allows the dog to regain joyful freedom of movement. A macroscopic-anatomic examination of 16 canine hips furnished new findings and knowledge in the field of veterinary medicine on the sensitive innervation of the canine hip joint capsule. Accordingly, the craniolateral area of hip joint capsule is innervated by rami articulares of N. glutaeus cranialis, the caudolateral area by rami articulares of N. ischiadicus and the medial area by rami articulares of N. femoralis.

Anatomy and pathology of the aging spine

The vertebral column is a complicated anatomical structure which is composed of the intervertebral discs and the vertebrae. Both components develop special degenerative changes and morphologic features during life. This paper first reviews the anatomical fundamentals and then describes the morphological features of the aging intervertebral disc and the subsequent osseous changes of the vertebral bodies and the zygapophyseal joints. The aging intervertebral disc is characterised by processes which are labeled as intervertebral chondrosis and intervertebral osteochondrosis. Often these processes are combined with typical dislocations of intervertebral disc tissue in an anterior or dorsolateral direction. The well known Schmorl's nodules must also be mentioned in this context. Furthermore calcification and ossification of the intervertebral disc tissue can take place. More severe processes lead to osseous changes of the vertebral bodies. In particular, an osteophytosis of the vertebral bodies can be established. These sturdy osteophytes are able to stiffen the vertebral column. Furthermore the arthrotic changes of the zygapophyseal joints are delineated in this paper. The special appearances of these changes are discussed according to the different and specialised regions of the vertebral column. The advanced degenerative changes of the zygapophyseal and uncovertebral joints of the cervical spine are of essential clinical interest because the compression of the vertebral artery or the narrowing of the intervertebral foramina by these processes may cause severe neurological symptoms. The arthrotic changes of the medial atlantoaxial joint, which lead to the crowned odontoid, and the pseudospondylolisthesis (so called M. Junghanns) of the lumbar spine must also be mentioned. It is the aim of this paper, not only to explain and review the degenerative changes, but to illustrate the anatomy and pathology of the aging spine on the basis of macerated osseous specimens in order to make radiological investigations and pictures more understandable and clear.

Anatomic and functional aspects of the kinetics of the shoulder joint capsule and the subacromial bursa

This anatomic study was devoted to the kinetics of the shoulder joint and especially the subacromial region. Following dissection of the shoulder joint capsule and subacromial region of 80 unpreserved shoulder joints, the anatomic relationships of the subacromial space in the neutral position and in continuous abduction (30 degrees, 60 degrees and 90 degrees with fixed scapulae) were examined. These investigations were supplemented by histologic preparations. In the course of our examinations we discovered a gliding mechanism of the subacromial bursa. Moreover, we found a subcoracoid attachment of the shoulder joint capsule and a precoracoid ligamentous connection running between the short head of the biceps brachii m. and the coracoacromial ligament. We termed this the coracoid aponeurosis, which facilitates gliding behaviour of the shoulder joint capsule beneath the coracoid process. In view of this gliding mechanism of the subacromial bursa and the coracoid aponeurosis, discovered in the course of our investigations, we have to reassess the kinetics of the sub-acromial and subcoracoid space. Further, we should reconsider our operative technique in cases of the subacromial or subcoracoid impingement syndrome.

Mechanisms of accumulation of small particles of iron oxide in experimentally induced osteosarcomas of rats: a correlation of magnetic resonance imaging and histology. Preliminary results

RATIONALE AND OBJECTIVES

This study was conducted to investigate the distribution and kinetics of small particles of iron oxide in osteosarcoma-like tumors.

METHODS

Magnetic resonance (MR) imaging was performed in eight athymic nude rats with an experimentally induced osteosarcoma of the right hind leg immediately after intravenous injection of a superparamagnetic iron oxide preparation. Five animals received 150 mumol iron oxide/ kg and three received 50 mumol iron oxide/kg. The iron oxide preparation consisted of polythylenglycol-coated particles with a core diameter of 6 to 8 nm. The MR images were correlated with histologic slices of the tumors.

RESULTS

The tumors accumulated iron oxide rapidly. A marked decrease in signal intensity, preferentially along the periphery of the tumor, was followed by a partial return of the signal intensity within the first minute. The maximum signal decrement throughout the entire tumor exceeded 41% and 21% with one dose each of 150 mumol iron/kg and 50 mumol iron/kg, respectively. The rate of return depended on the injected dose and tumor area, with the signal intensity approaching the initial value before the injection of iron oxide after 45 minutes. Histologic correlation only showed deposition of contrast medium in the proliferative areas of the tumors, mainly confined to the tumor margin. In addition to a predominantly extracellular deposition, intracellular storage could be detected.

CONCLUSIONS

The findings help to advance the understanding of the distribution and kinetics of intravenous-injected small particles of iron oxide in osteosarcoma-like tumors. A first-pass accumulation of iron oxide could be documented by MR imaging in the periphery of osteosarcomas. Due to sieving of iron oxide particles by liver, spleen, and bone marrow, the signal intensity at 45 minutes after the injection of iron oxide returned to 89% (150 mumol iron oxide/kg) and 95% (50 mumol iron oxide/kg) of the preinjection intensity.