Influence of the initial rupture size and tendon subregion on three-dimensional biomechanical properties of single-row and double-row rotator cuff reconstructions.

PURPOSE: Influence of the initial rotator cuff tear size and of different subregions of the SSP tendon on the cyclic loading behavior of a modified single-row reconstruction compared to a suture-bridging double-row repair. METHODS: Artificial tears (25 and 35 mm) were created in the rotator cuff of 24 human cadaver shoulders. The reconstructions were performed as a single-row repair (SR) using a modified suture configuration or a suture-bridge double-row repair (DR). Radiostereometric analysis was used under cyclic loading (50 cycles, 10­180 N, 10­250 N) to calculate cyclic displacement in three different planes (anteroposterior (x), craniocaudal (y) and mediolateral (z) level). Cyclic displacement was recorded, and differences in cyclic displacement of the anterior compared to the posterior subregions of the tendon were calculated. RESULTS: In small-to-medium tears (25 mm) and medium-to-large tears (35 mm), significant lower cyclic displacement was seen for the SR-reconstruction compared to the DR-repair at 180 N (p ≤ 0.0001; p = 0.001) and 250 N (p = 0.001; p = 0.007) in the x-level. These results were confirmed in the y-level at 180 N (p = 0.001; p = 0.0022) and 250 N (p = 0.005; p = 0.0018). Comparison of the initial tear sizes demonstrated significant differences in cyclic displacement for the DR technique in the x-level at 180 N (p = 0.002) and 250 N (p = 0.004). Comparison of the anterior versus the posterior subregion of the tendon revealed significant lower gap formation in the posterior compared to the anterior subregions in the x-level for both tested rotator cuff repairs (p ≤ 0.05). CONCLUSIONS: The tested single-row repair using a modified suture configuration achieved superior results in three-dimensional measurements of cyclic displacement compared to the tested double-row suture-bridge repair. The results were dependent on the initial rupture size of the rotator cuff tear. Furthermore, significant differences were found between tendon subregions of the rotator cuff with significantly higher gap formation for the anterior compared to the posterior subregions.

Temperature elevation during simulated polymethylmethacrylate (PMMA) cranioplasty in a cadaver model.

The aims of this study were to: (i) obtain temperature measurements during in vitro polymerisation of polymethylmethacrylate (PMMA) disks of a range of thicknesses; and (ii) obtain tissue temperature measurements at various locations within a skull defect during a simulated PMMA cranioplasty procedure using a cadaver. In vitro, higher temperatures were recorded with increasing PMMA thickness. During the simulated cranioplasty, the maximum temperature was observed inside the PMMA sample, with nearby tissues being exposed to temperatures of greater than 50 degrees C over prolonged periods. There is conflicting information in the literature concerning the sensitivity of brain tissue and bone to elevated temperatures. Preoperatively fabricated PMMA cranioplasty prostheses are recommended.

CAD generated mold for preoperative implant fabrication in cranioplasty.

Intraoperative fabrication of acrylic cranial implants may be difficult and will increase operation time. In addition forming implants directly on the defect, intracranial tissues are exposed to heat of polymerization and residual monomer, that occurs, when autopolymerizing methyl methacrylate is used intraoperatively. Furthermore the cosmetical result may be unacceptable. Preoperatively formed acrylic implants may reduce these disadvantages compared to conventional techniques in cranioplasty. We will present methods for preoperative fabrication of cranial implants for a cadaver specimen. Implants were fabricated using a Rapid prototyping (RP) models of the skull built by Fused Deposition Modeling (FDM). In addition a mold of the defect was generated by CAD techniques, that can serve as a template for implant design.

The anterior glenohumeral joint capsule: macroscopic and MRI anatomy of the fasciculus obliquus or so-called ligamentum glenohumerale spirale.

The purpose of this study was to demonstrate the macroscopic and MRI anatomy of the fasciculus obliquus, otherwise known as the ligamentum glenohumerale spirale or spiral GHL of the anterior shoulder joint capsule. Conventional and MR arthrography (1.5-T device Somatom Symphony, Siemens with shoulder coil) images in standard planes were compared with gross anatomic dissection findings in six fresh shoulder specimens from three cadavers. The MR imaging protocol included T1, PD and DESS 3D WI sequences. The macroscopically recognisable band-the spiral GHL-was identified by anatomic dissection and MRI in all the specimens. It was best visualised by MR arthrography on axial and oblique sagittal planes (T1; PD WI) and appeared as a low signal intensity stripe within the superficial layer of the anterior joint capsule. The absence of the variable middle glenohumeral ligament did not influence the anatomic properties and the MR imaging of the spiral GHL. Diagnostic visualisation of the normal anatomic structures is a prerequisite to distinguish between normal and pathologic conditions. Anatomy of the spiral GHL can be used by radiologists for more detailed interpretation of the anterior shoulder joint capsule ligaments on MR images.

Medical biomodelling in surgical applications: results of a multicentric European validation of 466 cases.

The study started in September 1999 and ended in April 2002. It is based on a questionnaire [www.phidias.org] assessing case-related questions due to the application of stereolithographic models. Each questionnaire contains over 50 items. These variables take into account diagnosis, indications and benefits of stereolithographic models with view on different steps of the surgical procedures: preoperative planning, intraoperative application and overall outcome after surgical intervervention. These questionnaires were completed by the surgeons who performed operation. Over the time course of our multicentric study (30 months), we evaluated 466 cases. The study population consists of n=231 male and n= 235 female patients. 54 surgeons from 9 European countries were involved. There are main groups of diagnosis that related to the use of a model. Most models were used in maxillofacial surgery. The operative planning may help to determine the resection line of tumor and optimize reconstructive procedures. Correction of large calvarian defects can be simulated and implants can be produced preoperatively. Overall in 58 % of all cases a time- saving effect was reported. The study strongly suggests, that medical modeling has utility in surgical specialities, especially in the craniofacial and maxillofacial area, however increasingly in the orthopedic field. Due to our results, medical modeling optimizes the preoperative surgical planning. Surgeons are enabeled to perform realistic and interactive simulations. The fabrication of implants, its design and fit on the model, allow to reduce operation time and in consequence risk and cost of operation. In addition, the understanging of volumetric data is improved, especially if medical models are combined with standart imaging modalities. Finally, surgeons are able to improve communication between their patientents and colleagues.

Anatomical accuracy in medical 3D modeling.

In complex surgery, medical modeling has become an accepted tool for diagnosis, simulation and the planning of surgical interventions [1]. However, the question concerning the accuracy of the model, i.e. the equivalence between the model itself on the one hand and the original anatomical situation on the other hand, remains unanswererd in the current literature.

Anatomical composition of the anterior shoulder joint capsule. A cadaver study on 12 glenohumeral joints.

Twelve right cadaver shoulder joints were investigated after alcohol-formalin-glycerol fixation. The tendons of the "rotator cuff" were separated from the joint capsule. The capsulo-ligamentous structures: Lig. coracohumerale, Lig. coracoglenoidale and Ligg. glenohumeralia were dissected. In addition to the Ligg. glenohumerale superius, medium et inferius, an "unknown glenohumeral ligament" coursed in the midline of the superficial layer of the anterior shoulder joint capsule. It arose from the axillary part of the Lig. glenohumerale inferius and the insertion tendon of the Caput longum m. tricipitis brachii, coursed upwards laterally and fused with the Lig. glenohumerale medium. Between the Ligg. glenohumerale medium et inferius it was connected with the shoulder joint capsule by loose connective tissue. Craniolaterally it melted into the superior portion of the M. subscapularis and inserted together with its tendon to the Tuberculum minus of the Humerus. The ascending fibres of the "unknown glenohumeral ligament" and the oblique, descending fibres of the Ligg. glenohumeralia medium et inferius crossed twice and formed X-shape connections between the ligaments. In external rotation and abduction or anteversion the course of fibres of the "unknown glenohumeral ligament" was spiral. According to the shape and anatomical position of the "unknown glenohumeral ligament" we propose to name it "Lig. glenohumerale spirale".

Anatomy of the coracohumeral and coracoglenoidal ligaments.

The Ligg. coracohumerale and coracoglenoidale are constant anatomical structures, represented in all the 34preparations investigated. The Lig. coracoglenoidale is a strong band of dense connective tissue, running from the Processus coracoideus to the Tuberculum supraglenoidale. In 27 specimens out of 34 it was the continuation of the M. pectoralis minor tendon. The Lig. coracohumerale consists of two separate parts. The "inferior part" originates from the Processus coracoideus and the Lig. coracoglenoidale, which separates it from the base of the coracoid process. It is composed of the joint capsule anteriorly and a remnant of the M. pectoralis minor tendon posteriorly. The "superior part" arises from the medio-posterior surface of the Processus coracoideus, just below the Lig. coracoacromiale. Both parts of the Lig. coracohumerale run into the shoulder joint capsule under the M. supraspinatus tendon and insert into a capsular semicircular band. According to the shape and course of fibres between the greater and lesser tubercles of the Humerus, we propose to name it the "Lig. semicirculare humeri". None of the two parts of the Lig. coracohumerale begins from the base of the Processus coracoideus, and fibres of the Lig. coracohumerale do not reach the Tuberculum majus et minus directly.

[An interuniversity comparison of the supervision of doctoral candidates--should the promotion procedures be changed?]. / Betreuung medizinischer Doktoranden im interuniversitären Vergleich--Sollte das Promotionsverfahren geändert werden?

BACKGROUND AND OBJECTIVE: There are only few investigations on supervision of medical dissertations that allow a comparison between different universities. This article discusses how the medical dissertation can be incorporated into a new medical curriculum. METHODS: A questionnaire was sent to all medical students in Lübeck who wrote dissertations in 1998. It contained 28 questions on duration, supervision, impact on medical studies and possible changes in the dissertation process. The data were compared statistically to previous studies. RESULTS: 70 questionnaires could be evaluated (63%) which allowed a comparison with studies in Hannover and Erlangen-Nürnberg. The Lübeck students assessed their supervision to be significantly better, they worked more frequently on experimental topics and data of their research were published more often than was the case in the other two institutions. The students regularly needed one extra semester for their dissertation, especially those working on experimental topics. Those who wrote dissertations expressed criticism of the dissertation process: only one third were in favour of making no change in the process. When asked to suggest possible improvements they proposed having a central facility for the announcement of dissertation subjects and one free semester to work solely on the dissertation. CONCLUSION: In order to evaluate and compare supervision of dissertations, a comparable questionnaire should be used by all medical universities. If the medical curriculum is changed, the dissertation either has to be firmly integrated in the curriculum or it should be undertaken after completion of the studies.

[PGP 9.5 immunohistochemical study on the development of the enteric nervous system of trisomy 16 mouse embryos and their normal littermates].

OBJECTIVE: To study the development of the intestinal innervation of trisomy 16 mouse embryos and their normal littermates from embryonic days 13-18 (ED13-ED18). METHODS: (1) Trisomy 16 mouse embryos used in this study were produced by crossing NMR-1 females with males carrying the two Robertsonian (Rb) translocation chromosomes Rb (11, 16) and Rb (16,17) 8 LubtwLub3. (2) Cytogenetic analysis: accurate ascertainment of trisomy 16 was provided by the demonstration of two Rb metecentric chromosomes and a count of 41 chromosome arms. (3) Rabbit-anti-human protein gene product 9.5 antibody was used in PAP and Avidin-biotin methods: RESULTS: At ED13, neither nervous plexuses nor neurons were found in the gut of trisomy 16 mouse embryos and their normal littermates. And in the gut of normal littermates there appear only a scattering neurons with light staining nucleuses at ED14, the irregular network of the myenteric plexus composed of scattering distribution neurons and their processes at ED15 and the regular meshworks of the myenteric plexus with developed ganglia at ED16. However, in trisomy 16 mouse embryos at ED14-ED16, enteric nervous system (ENS) was composed of only some scattering neurons with different distribution density and size. The development of ENS was well in ED17-ED18 normal littermates. The developed myenteric plexus was composed of nervous meshworks with regular distribution. The submucosal plexus had irregularly shaped. The interconnecting strands were frequent visible between the myenteric and submucosal plexuses. In the gut of trisomy 16 mouse embryos the submucosal plexus was absent and the development and differentiation of the myenteric plexus were lower compared with their normal littermates. An important finding was that 5 mm aganglionic bowel was firstly found in the end of colon. In this study, the developed mesentery nervous fibers were persent and innervated in both type animal guts from ED14 to ED18. CONCLUSIONS: It was original report to find the developmental delay of the ENS, absence of submucosal plexus and the aganglionic segment of colon ending in trisomy 16 mice, an animal model for Down syndrome.

Germ cell migration and early development of the gonads in the trisomy 16 mouse--an animal model for Down's syndrome.

The aneuploid condition of patients with Down's syndrome (trisomy 21) frequently leads to a sub- or infertility of these individuals. Gonads from adults and fetuses with trisomy 21 demonstrated histologically a remarkable reduction in germ cells. Disorders in the germ cell migration, the early development of the gonads as well as meiotic defects are thought to contribute to this pathomorphology. To gain information about premeiotic defects, investigations on the trisomy 16 mouse, an animal model for Down's syndrome, were carried out. By means of morphometric studies a delay in migration and a reduction in primordial germ cells was evaluated in trisomic mice of embryonic day 11 (E11). At day E13 a generalized growth retardation of the developing gonads was obvious in trisomic animals. Additionally performed electron microscopic examinations revealed signs of germ cell demise in trisomy 16 mice. Thus, the mechanisms of a diminished proliferation capacity, impaired migration and premature death of germ cells represent premeiotic disorders that presumably contribute to the pathomorphology observed in the gonads of individuals with Down's syndrome.

Congenital colonic hypoganglionosis in murine trisomy 16--an animal model for Down's syndrome.

Human trisomy 21 (Down's syndrome) affects the development of multiple organ systems frequently including gastrointestinal anomalies such as Hirschsprung's disease. To elucidate the underlying morphogenetical mechanisms a murine model (trisomy 16 mouse) for Down's syndrome has been established. However, previous studies on trisomy 16 (TS 16) mice have been confined to non-enteric developmental disorders. Therefore, the aim of the present study was to assess the enteric nervous system and the morphology of the terminal colon in TS 16 mice during late intrauterine development. Immunohistochemical examination (protein gene product 9.5) revealed a reduction of myenteric ganglionic size and density as well as the presence of ectopic ganglia, thus resembling typical features of colonic hypoganglionosis and myenteric heterotopia. Enzyme histochemistry for NADPH-diaphorase showed a remarkable decrease of NADPH-positive neurons in TS 16 mice, whose sparse distribution was confined to a minor portion of the oligoneuronal myenteric ganglia. Electron microscopical studies of TS 16 mice confirmed the myenteric hypoganglionosis and, additionally, demonstrated the absence of submucosal neurons. Whereas neurons of controls were characterized by arborizing neuronal processes, neurons of TS 16 mice were reduced in size and exhibited only few and shortened cytoplasmic protrusions. Additionally, prominent bundles of parallel nerve fibers passed through the intermuscular zone and lacked the arborization pattern of normal neuropil. They were not observed in controls and resembled features of extrinsic nerves. Approximately one third of TS 16 mice developed a colonic dilatation proximally to an obstructed segment characterized by a pronounced hypoganglionosis. Although TS 16 mice did not develop complete aganglionosis, the abundance of nerve fiber bundles and the colonic dilatation were consistent with the morphological characteristics of Hirschsprung's disease. The findings suggest that even a hypoganglionosis characterized by ultrastructurally altered and NADPH-diaphorase-deficient neurons may be capable of provoking a functional intestinal obstruction. Similar abnormalities of the enteric nervous system as observed in TS 16 mice may also be present in such trisomy 21 patients who suffer from chronic intestinal motility disorders which are not caused by complete aganglionosis.

[The development of the enteric nervous system in terisomy 16 mice with the occurrence of congenital megacolon].

OBJECTIVES: To study the developmental defect of the enteric nervous system in trisomy 16 mice, an animal model for Down syndrome, and reveal the possibility of trisomy 16 mice with congenital megacolon. METHODS: We performed trisomy 16 mouse breeding, cytogenetic analysis of trisomy 16 mouse embryos and their normal litteermates from embryo day 13-18 (ED13-ED18), protein gene product 9.5 (PGP 9.5) immunohistochemistry in section and whole mount preparations. RESULTS: Developmental delay of ENS was present in trisomy 16 mouse embryos by comparison with their normal littermates. No submucosal plexus was found in gut except 5 mm aganglionic bowel aparting from anus in trisomy 16 mice. The developed mesentery nervous fibers were shown as well as the innervated gut of trisomy 16 mouse embryos and their normal littermates. CONCLUSION: Trisomy 16 mice occur with congenital megacolon, and trisomy 16 mice may be also regard as an animal model for Hirschsprung's disease.

The embryonic development of sensory organs and the skull in the trisomy 16 mouse, an animal model for Down's syndrome.

The trisomy 16 mouse is a widely accepted animal model for the study of the embryonic development of human trisomy 21. While the development of the brain and heart has been thoroughly studied, there are hardly any data on the development of sensory organs like the eye, nose and ear. By studying scanning electron microscopic pictures and semithin sections from the tenth to the 15th day of development, we found delayed development of the nose, and, in particular, of the vomer. Sensory structures of the otic vesicle also showed a marked developmental delay. Pigmentation of the outer layer of the otic cup starts later in trisomic animals. Cleared specimens on day 16 showed retarded development of ossification centres in all areas of the skull. These findings correspond with the abnormal facial morphology found in Down's syndrome and may also provide new insights into the hearing impairment commonly found. The observations in the eye and skull bones indicate that neural crest tissue maldevelopment is not the sole cause of malformations.

[Preparation of critical point dried specimens of mouse embryos with a laser scalpel]. / Präparation critical-point-getrockneter Mausembryonen mit einem Laserskalpell.

We investigated the use of a laser scalpel for tissue sparing demonstration of the deep structures of critical point dried specimens. A Nd:YAG-Laser emitted pico-second pulses (wavelength 1064 nm, pulse width 30 ps) at pulse energies varying from 1 microJ to 6 mJ was used. Differences in the effects on sputtered and unsputtered specimens were found. We separate the floor of the mouth and pharyngeal fornix in mouse embryos (10. developmental day). It was concluded the laser scalpel is superior to conventional mechanical dissecting methods when applied to small dried specimens. The advantages and disadvantages of the laser scalpel are discussed.

Rabbit endometrium in organ culture: morphological evidence for progestational differentiation in vitro.

This communication describes conditions for long-term organotypic culture of rabbit endometrium allowing progesterone-induced transformation, as typical for early pregnancy, to continue in vitro. This system appears to compare favorably with in vitro models so far proposed for the study of hormonal control of uterine function or for the investigation of cell-biological aspects of embryo implantation. The specific aim in the presented system is to provide approximate normal epithelium-stroma interrelationships. Fragments of endometrium consisting of epithelium and stroma were obtained during early pseudopregnancy and cultured on a gyratory shaker. Morphology was investigated by light microscopy, transmission and scanning electron microscopy. During the first two days the epithelium grows over the exposed stroma regenerating a complete epithelial lining. No central necrosis is found in the stroma for up to 6 days, and the tissue keeps its organotypic architecture although certain morphological differences can be observed between regenerated versus original epithelium. In the regenerating portion a stage-specific cell differentiation and the reformation of a basal lamina are missing. Progesterone substitution preserves cell morphology and allows to maintain, in vitro, the stage-specific pattern of cell organelles. Most characteristic is the induction of extensive fusion of epithelial cells. These large symplasms are comparable in size and structure to those formed in pregnancy in the implantation chamber in vivo. Only the superficial parts of the original (not the regenerated) epithelium are capable of progesterone-induced large-scale fusion. This organotypical culture system appears to be of potential value for in vitro studies on hormone action and on endometrial receptivity for embryo implantation.

Transformation of endometrium and fertility in late stages of pseudopregnancy in the rabbit.

Ovulation was induced in rabbits between Days 14 and 18 of pseudopregnancy by an intravenous injection of hCG. Induction of ovulation from Day 16 onwards led to normal progestational endometrial transformation. In rabbits injected on Day 14 or 15, a normal preimplantation endometrial morphology developed, but not earlier than 7 days after hCG (Day 14/15 + 7). Uteroglobin secretion was advanced during the second pseudopregnancy. After mating or artificial insemination, fertility was greatest on Day 18 of pseudopregnancy. Conception failed on Day 14 and embryo transfers were unsuccessful on Day 14 + 1. Transfers performed on Day 14 + 3, however, led to implantation and offspring, even though endometrial morphology did not correspond to the normal Day 3 preimplantational morphology at the time of transfer. We conclude that endometrial transformation typical of normal pseudopregnancy can be induced by ovulation during the regeneration phase of pseudopregnancy from Day 16 onwards; fertilization and implantation can be achieved as early as Day 15 of pseudopregnancy; an oestrous period with high mating activity and fertility occurs about 3 days later; and Day 14 after hCG represents a limited time of functional change from pseudopregnancy to a fertile uterine cycle in the rabbit.

Regeneration of the uterine epithelium in later stages of pseudopregnancy in the rabbit. An ultrastructural study.

Morphological changes of the uterine epithelium in later stages of pseudopregnancy in the rabbit have been studied using different morphological methods. The highly proliferated mucosa with numerous symplasms of a pseudopregnant animal returns to the morphology of a nonpregnant animal by apoptosis, moderate necrosis and lytic transformation of symplasms back to typical endometrial cells without desquamation of cells. The first signs of lytic transformation are observed on Day 8 of pseudopregnancy. Enhanced regeneration with apoptosis and lysis of the symplasmic nuclei is observed between Day 14 and Day 16. Full restoration of the epithelium with reappearance of ciliated cells, typical columnar and partly mucified epithelial cells is not completed earlier than Day 24 p. hCG. This epithelium, however, differs clearly from the epithelium of a virgin rabbit due to several residues of epithelial transformation. Thus, from a morphological point of view, pseudopregnancy in the rabbit lasts up to or even longer than Day 28 p. hCG with persisting ultrastructural remnants of the preceding cycle.