Andreas Prescher

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. Furtherinvestigations must be conducted to validate the clinical applicability of this system.

The sensory innervation of the hip joint - an anatomical study

Typically obturator nerve blockade is used to relieve hip pain. It sometimes only has a minor effect in resolving symptoms. This clinical observation led us to examine comprehensively the sensory nerve innervation of formalin-fixed hip joint capsules. Following macroscopic preparation, the area of the hip joint capsule was inspected with the aid of an operating microscope. We discovered a separation between the anterior and posterior sensory innervation of the hip joint capsule. The anteromedial innervation was determined by the articular branches of the obturator n. Additionally, the anterior hip joint capsule was innervated by sensory articular branches from the femoral n. In the posterior part we found articular branches from the sciatic n., which in addition to the articular branches from the nerves to the quadratus femoris m., innervate the posteromedial section of the hip joint capsule. Moreover, articular branches of the superior gluteal n. were found, which innervate the posterolateral section of the hip joint capsule. This anatomical study demonstrates that the obturator n. block is insufficient for the treatment of hip pain. Further investigations will determine if these nn. can be reached percutaneously. Effective neural blockade of the hip joint must include the femoral n., the sciatic n. and the superior gluteal n.

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 Schmorls 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.

Anatomy of the SMAS Revisited

Despite the relevance of the superficial musculoaponeurotic system (SMAS) in facial rejuvenation a clear anatomic definition of the SMAS is still lacking. Therefore, the morphology of the SMAS in 18 cadavers was investigated using different macroscopic and microscopic techniques. The region-specific anatomy of the SMAS is described in the forehead, parotid, zygomatic, and infraorbital regions, the nasolabial fold, and the lower lip. The SMAS is one continuous, organized fibrous network connecting the facial muscles with the dermis. It consists of a three-dimensional scaffold of collagen fibers, elastic fibers, and fat cells. Two different types of SMAS morphology were demonstrated: type 1 SMAS architecture is located lateral to the nasolabial fold with relatively small fibrous septa enclosing lobules of fat cells, whereas type 2 architecture is located medial to the nasolabial fold, where the SMAS consists of a dense collagen–muscle fiber meshwork. Overall, it was demonstrated that different facial regions show specific morphological characteristics, and thus region-specific surgical interventions may be necessary in facial rejuvenation.

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.

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

Abstract.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.

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.

Fallopian canal dehiscences: a survey of clinical and anatomical findings

This survey investigates fallopian canal dehiscences in order to assess the risk of encountering an unprotected facial nerve during routine ear surgery. In a prospective non-randomized study, the intraoperative appearance of the facial canal in 357 routine ear operations was compared with 300 temporal bone specimens from 150 autopsies. Intraoperatively, a dehiscence was detected in 6.4% (23/357) of the operations, most frequently at the oval niche region (16/23 cases). The incidence increased with the number of operations (P<0.0002). Cholesteatoma surgery had the highest relative risk (RR 4.6) of exposing an unprotected facial nerve. Postoperatively, no persistent facial paralysis was observed. In four of five cases with a transient facial palsy due to local anesthetics, a bony dehiscence could be found. The anatomical study revealed fallopian canal dehiscences in 29.3% (44/150) of the autopsies. One-third (15/44) of the individuals affected displayed bilateral findings, thus resulting in 19.7% (59/300) of temporal bones affected. A total of 17/59 bones showed microdehiscences, and most (55/59) were located at the oval niche. The actual prevalence of fallopian canal dehiscences is significantly higher than intraoperative findings suggest. The oval niche is the most affected region. High-resolution computed tomography is of diagnostic value only in selected cases. Facial paralysis following local anesthesia is the most significant clinical sign. Vigilance in acute facial palsy after local anesthetics and in cholesteatoma surgery and adequate intraoperative exposure help to prevent iatrogenic injury of the uncovered nerve. In unclear cases, nerve monitoring can facilitate a safe outcome.

Fiber anatomy of dorsal and ventral language streams

Recent advances in neuroimaging have led to new insights into the organization of language related networks. Increasing evidence supports the model of dorsal and ventral streams of information flow between language-related areas. Therefore, a review of the descriptions of language-related fiber anatomy in the human and monkey brain was performed. In addition, case studies of macroscopical fiber dissection and polarized light imaging (PLI) with special focus on the ventral stream were done. Several fiber structures can be identified to play a role in language, i.e. the arcuate fasciculus as a part of the superior longitudinal fasciculus, the middle longitudinal fasciculus, the inferior fronto-occipital fasciculus, and extreme and external capsules. Substantial differences between human and monkey fiber architecture have been identified. Despite inconsistencies based on different terminologies used, there can be no doubt that dorsal and ventral language streams have a clear correlation in the structure of white matter tracts.

The glenoid notch and its relation to the shape of the glenoid cavity of the scapula

The prevalence of a notch in the anterior margin of the glenoid cavity of 236 scapulae (118 female, 118 male) was investigated. The notch was found in 129 scapulae (55%) and gave rise to a pear‐shaped cavity. In 107 scapulae (45%) the notch was absent, the shape of the cavity being oval. No sex difference was found in the prevalence of the notch. If a distinct notch exists, the glenoid labrum is not attached to bone at the notch and is therefore liable to be sheared off (Bankart lesion).