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One way to increase medical students' awareness of anatomical variability is the dissection of different cadavers throughout laboratory coursework. This report covers such a procedure successfully instituted in a human gross anatomy course.
Transmandibular implants (TMI) are indicated both for functional reconstruction of the severely atrophic mandible and when routine augmentation is unpredictable. This study investigates the interface of bone around a TMI, retrieved from the cadaver. The TMI had successfully functioned for 7 years. The mandible was immersed in 10% formaldehyde and sectioned into nine appropriate pieces. Samples were embedded in polymethylmethacrylate, and cut around the transosseous posts and cortical screws in both vertical and horizontal sections. Samples were analyzed at 400 MHz (nominal lateral resolution, 2.5 microm) using a UH3 Scanning Acoustic Microscope (Olympus, Tokyo, Japan). The middle of implant specimens 1-4 were cut to 50 microm, and stained by toluidine blue for light microscopy. Dental X-rays showed no bone resorption around any implant. On a 2-mm lateral scan, almost uniform interface space was seen between bone and implant surface in cortical screws. There are wider spaces around the transmandibular posts in the superior area. Histology revealed the small area of direct contact. There is bone marrow space in the interface, with no significant fibrous tissue. We interpret these results at the interface to be because of adaptation for stress distribution.
The impact of soft tissue in vivo on accuracy of bone mineral density (BMD) measurements of the spine and hip by dual energy X-ray absorptiometry and of the forearm by single photon absorptiometry was assessed by use of 14 human cadavers. The in vivo accuracy errors (SEE%) were: forearm 3-5%, anteroposterior spine 5.3%, lateral spine 10-12%, and femoral greater trochanter, neck, total, intertrochanteric, and Ward's triangle 3%, 6.5%, 6.7%, 8%, and 11-13%, respectively. Except from the lateral spine and the greater trochanter, the slopes of the linear regressions of in vivo BMD against in vitro BMD were not significantly different from 1 (p > 0.05). The calculated random accuracy error of BMD measurements due to fat inhomogeneity was estimated to 3-4% for the anteroposterior spine and 9-14% for the lateral spine (from abdominal computed tomography in 26 healthy women). In conclusion, acceptable accuracy errors below 6-7% (of soft tissue in vivo) of BMD measurements were obtained in the anteroposterior spine, the forearm, and the neck, greater trochanter, and total proximal femur.
The current criterion used by the automotive industry for injury to the lower extremity is based on visible bone fracture. Studies suggest, however, that chronic joint degeneration may occur after subfracture impact loads on the knee. We hypothesized that subfracture loading of the patellofemoral joint could result in previously undocumented microtrauma in areas of high contact pressure. In the current study, seven patellofemoral joints from human cadavers were subjected to impact with successively greater energy until visible fracture was noted. Transverse and comminuted fractures of the patella were noted at 6.7 kN of load. Approximately 45% of the impact energy then was delivered to the contralateral joint. Subfracture loads of 5.2 kN resulted in no gross bone fracture in five of seven specimens. Histological examination of the patellae horizontal split fracture in the subchondral bone, at the tidemark, or at the interface of calcified cartilage and subchondral bone. The trauma appeared predominantly on the lateral facet, adjacent to or directly beneath preexisting fibrillation of the articular surface. Surface fibrillation was noted in histological sections of control patellae (not subjected to impact loading), but occult damages were not observed. Although the mechanism of this occult trauma is unknown, similar damage has been shown to occur from direct shear loading. As these microcracks can potentiate a disease process in the joint, this study may suggest that the current criterion for injury, based on bone fracture alone, is not sufficiently conservative.
While attrition from sharp bony surfaces is the most common cause of extensor digiti minimi (EDM) tendon rupture, the etiology of other cases of spontaneous EDM tendon rupture is still unknown. Friction within the compartment may play a role, especially with ulna dislocation. The purpose of this study was to compare gliding resistance of the EDM tendon with that of a tendon which rarely ruptures spontaneously, the extensor digitorum communis of the middle finger (EDC III) tendon, under various wrist and ulna head positions. Eight fresh frozen cadavers were used. Gliding resistance between the tendon and its sheath in each compartment was measured in five different wrist positions and three different ulna head positions. Gliding resistance of the EDM tendon (0.13 +/- 0.03 N) was significantly greater than the EDC III tendon (0.09 +/- 0.03 N) (p < 0.05). For the EDM tendon, the gliding resistance in ulnar deviation or pronation was higher than the gliding resistance in neutral, radial deviation, or supination (p < 0.05), and the gliding resistance with ulnar lengthening (over 6 mm) or dorsal ulnar dislocation (over 9 mm) was higher than in neutral ulnar head positioning. For the EDC III tendon, the gliding resistance in ulnar deviation was significantly higher than the gliding resistance in neutral, radial deviation, or supination, or dorsal dislocation with ulnar lengthening (p < 0.05). Wrist ulnar deviation, ulnar dorsal dislocation (over 9 mm), and ulnar lengthening (over 6 mm) increased the gliding resistance of the EDM tendon. In patients at risk for EDM rupture, such as those with rheumatoid arthritis or distal radioulnar joint osteoarthritis, avoiding such positions may be advantageous.
The objective of this study was to develop an MR-based technique for quantifying the deformation of articular cartilage during mechanical loading in an intact cadaver joint at high spatial and temporal resolution. A nonmetallic pressure device was constructed for applying loads of >1000 N to a femoro-patellar articulation within an extremity coil of a clinical 1.5 T MRI scanner. Digital image processing methods were used to determine the location- and time-dependent cartilage deformation in consecutive 2D fat-suppressed FLASH images. Additionally, three-dimensional reconstruction of the cartilage was performed from 3D fat-suppressed FLASH image data. During the first 10 min of static compression, thickness changes between 10 and 30% were observed. Thickness changes greater than 50% and volume changes of 20% were recorded after 3 h. The technique permits analysis of the load and time-dependent mechanical behavior of articular cartilage in its natural environment.
Retinal pigment epithelium transplantation has been proposed as adjunctive treatment for age-related macular degeneration following surgical excision of choroidal neovascular membranes. The goal of this study was to develop a model to evaluate retinal pigment epithelium transplantation onto human Bruch's membrane in vitro. We investigated the ability of cultured fetal human retinal pigment epithelium to colonize human cadaver Bruch's membrane, determined the incubation time needed to form a monolayer and to exhibit apical microvilli and tight junctions, and assessed the production of basement membrane. Freshly enucleated (less than 48 hours old) human eyes were cut through the pars plana, and the anterior segment, vitreous, and retina were removed. The native retinal pigment epithelium was debrided with a surgical sponge. Bruch's membrane and choroid at the macula were trephined with a 7.0 mm diameter trephine and then incubated with 1/2 ml of Dulbecco's modified Eagle's medium +15% fetal calf serum+basic fibroblast growth factor (1 ng ml-1), and fetal human retinal pigment epithelium at a concentration of 242,000 cells ml-1. Specimens were incubated for 1, 4, 6, 8, 12, or 24 hours. The specimens were fixed in half strength Karnovsky's fixative, processed, and analysed with scanning and transmission electron microscopy. The retinal pigment epithelium covered the debrided macular specimens to different degrees at different incubation times. After 1 hour, the cells started to attach and flatten (median percent coverage: 78%). The extent of Bruch's membrane coverage by fetal retinal pigment epithelium varied greatly between specimens. After 4-6 hours, the cells covered the entire debrided surface in a monolayer (median percent coverage: 97.2% at 4 hours, 99.8% at 6 hours). Tight junctions were observed, and the cells had few apical microvilli. The lateral cell borders were obliquely oriented with respect to Bruch's membrane, and the nuclei were elongated, exhibited prominent nucleoli, and were oriented parallel to Bruch's membrane. After 6-8 hours, cells started to become hexagonal (median percent coverage at 8 hours: 99.97%). Cells attached to the inner collagenous layer tended to be flatter than cells attached to residual native basement membrane. At 12 and 24 hours, expression of hexagonal shape, tight junctions, and apical microvilli were observed more frequently (median percent coverage: 99.87% at 12 and 100% at 24 hours). No newly formed basement membrane was observed at these time points. In separate experiments comparing attachment in the presence and absence of native RPE basement membrane, the presence of native retinal pigment epithelial basement membrane promoted the early attachment of the cells and more rapid expression of normal morphology. This in vitro system provides a reproducible way to study the adherence of retinal pigment epithelium to normal and diseased human Bruch's membrane.
OBJECTIVE: The aim of this study was to study the role of the triangular fibrocartilage of the wrist in attenuating and transmitting axial force on the ulnar side of the wrist. DESIGN: Ten biopsies from the triangular fibrocartilage of fresh cadaver wrists were subjected to repetitive axial load during 4 h under reproducible conditions. Another five biopsies were subjected to a higher load and for a longer compression time. Finally, five biopsies were compressed at a (three times) higher compression rate. The amount of force transmitted and attenuated as well as the loaded deformation was measured. RESULTS: From the first experiment we concluded that 53% of the axial force was attenuated. More force was attenuated (61%) if the axial load was increased but still kept within the physiological boundaries. However, increasing the compression rate beyond the physiological boundaries showed that only very little force is attenuated (11.2%). CONCLUSION: The triangular fibrocartilage of the wrist has an important force attenuating function and should not be easily resected.
Donor-recipient incompatibility (D + R -) for HLA-DQ1, but not for -DQ2 or -DQ3, is associated with an adverse effect on cadaver kidney graft survival. Until now, however, DQ1 recipients of DQ1-negative kidneys (D - R +) have not been differentiated from DQ1-identical donor-recipient pairs (D + R +) and splits of DQ1, DQ5 and DQ6, have not been studied in that respect. From our data (480 transplantations performed from January 1980 to December 1990), three donor-recipient DQ combinations (D + R +, D - R +, D + R -) were formed for each of four DQ specificities (DQ2, DQ3, DQ5, DQ6). As DR-DQ linkage disequilibrium is well conserved in caucasoid individuals, DQ specificities were inferred from the associated DR specificities. Graft survival rate (%) was significantly lower for the DQ5 D + R - and the DQ6 D - R + combinations when compared with the other corresponding DQ combinations, whereas no significant difference was observed between the DQ2 and DQ3 combinations. In conclusion, if DQ1 plays a prominent role in kidney graft survival, the effects of its splits appear dissociated: DQ5 could be a marker of high antigenicity and DQ6 a marker of high responsiveness.
In this study, four different types of osteotomes were compared in lateral osteotomy of cosmetic rhinoplasty. For this purpose, 32 halves of 16 cadavers were used. Fracture line and mucosal injuries were evaluated. Statistical analyses were made to find out if there is any relation between the type of osteotomes and the extent of injury. At the same time bone thickness was measured on the osteotomy line. Wide osteotomes have shown more mucosal injuries which is statistically significant. Bone thickness does not exceed 3 mm at any point on the osteotomy lines.
The fibronectin plasma levels of 17 patients undergoing cadaver kidney transplantation were determined serially in the postoperative course using laser nephelometry. While 9 patients retained their grafts (group A), the grafts of 8 patients had to be removed (group B), mainly due to rejection, 3 patients had severe infections. In both groups a significant drop of the plasma fibronectin occurred after surgery. There were no significant differences between the two groups in the mean fibronectin levels. After the initial drop the group A patients exhibited rising values leading to a stable level. Progressively declining fibronectin plasma concentrations were found in 2 of 3 severely infected patients. Fluctuating values were found in 3 group B patients without a clear correlation to the rejection crises or the kidney function. The data suggest that the fibronectin plasma level does not seem to be a prognostic marker for graft rejection. But it might be useful in the important and often difficult differentiation between rejection and infection.
The currently study focused on the influence of delayed graft function on the long-term graft success rate in cadaver kidneys without any mismatches for HLA-DRB1. Donor-recipient HLA-DRB1 was determined by the significant two-locus linkages of HLA-B and -DRB1. The overall 5-year graft success rate was 88% in an HLA-DRB1-compatible group, significantly higher than the 69% in an HLA-DRB1 mismatch group (P < 0.05) and the 66% in an HLA-DR mismatch (P < 0.01). Delayed graft function was observed in 182 of 223 transplants. This high incidence of 82% is due to the fact that, in Japan, kidney procurement may only occur after cardiac arrest. The incidence did not differ in each group. The 5-year success rate for grafts with delayed function was 87% in the HLA-DRB1-compatible group, again significantly superior to the 68% in the HLA-DRB1 mismatch group and the 63% in the HLA-DR mismatch cases (P < 0.05). There was, thus, no difference in graft success rate for each group, with or without delayed graft function. Consequently, we feel that delayed graft function has no impact on the long-term outcome in transplants without mismatches for HLA-DRB1.
The predictive value of varying levels of antibody activity, its class and antigen specificity in sera of 81 recipients of cadaver renal allografts was evaluated. Recipients for transplantation were selected on the basis of a negative dye uptake T-cell crossmatch, after which the more sensitive 51Cr release technique was employed in a blind study using unseparated donor target cells. Recipient sera with peak panel reactivity and current samples were evaluated before and after reduction with dithiothreitol to destroy the IgM subclass. Double absorption with pooled platelets allowed antibodies against HLA class I antigens to be distinguished from those against HLA class II/non-HLA antigens. Optimal levels of cytotoxicity were established, giving a sensitivity of 73%. Data were assessed in terms of positive predictive value, and showed that conventional T-cell crossmatching is adequate for the primary transplant group, but more sensitive ancillary tests are indicated for regrafts. In this category of patients, IgG antibodies, whether against HLA class I antigens or HLA class II/non-HLA antigens, were highly predictive of early graft loss (positive predictive value 50%-100%). Using this protocol for patient selection, 1-month graft survival would have improved from 73% to 96%.
The introduction of genomic HLA-DR typing has stimulated a re-evaluation of the role of HLA-DR compatibility on cadaver kidney transplantation. We retrospectively studied the influence of HLA-DRB1 matching on the survival of 416 patients using univariate and Cox regression analysis as well as its influence on the occurrence of rejection episodes and on creatinine level at the 3rd month in the 198 recipients for whom these data were available. The following parameters were also considered: HLA-A,B compatibility, donor and recipient age, graft number, pre-transplant blood transfusions and panel reactive antibodies (PRA). Twenty-four month graft survival was 100% for transplants with zero mismatches (n = 47), 87.9% for those with one mismatch (n = 191) and 81.3% for those with two mismatches (n = 178). In the Cox model, HLA-DRB1 matching was the most significant variable influencing graft survival (47% of chi 2 P = 0.001), followed by HLA-A,B matching (23%, P = 0.02) and donor age (19%, P = 0.04). Ninety-two percent of the patients with zero mismatches experienced no rejection episodes in the first 3 posttransplant months compared with 62% and 41% of patients with one and two mismatches, respectively. Mean creatinine level (mg/dl) was 1.2, 1.4, and 1.5 in patients with zero, one, and two mismatches, respectively. Should these results be confirmed by prospective studies, HLA-DRB1 compatibility will have to be considered as an organ allocation criterion.
On the basis of previous studies showing good correlations between the structural strength of the femur and bone mass as assessed by single energy quantitative computed tomography, this study was scheduled to analyze the mode of failure of an oblique osteotomy in the distal femur in geriatric cadavers stabilized by an AO condylar plate and Grosse-Kempf locked intramedullary nail in axial eccentric loads and to relate the mode of failure to bone mineral content. A pilot study of two pairs of osteotomized, internally fixed femora were loaded axially and the loads correlated with bone mineral content. These correlations were used to calculate estimated failure load in 12 pairs of osteotomized femora (12 plated and 12 nailed specimens) which then were sustained to a cyclic eccentric axial load of 50% of the estimated failure load. The failure patterns in the two groups were different. Fixation failure occurred in all specimens in the plated group at the site of the osteotomy, while in the nailed group the fixation failures in 50% of the specimens were unrelated to the site of the osteotomy. The study suggests that locked intramedullary nailing of a distal femoral fracture in osteoporotic bone gives more secure fracture retention than fixation with a 95 degrees AO/ASIF condylar plate. Furthermore, it shows that bone mineral assessment by densitometric methods can be used to predict the mechanical strength of a bone/implant construct.
To determine the isometric points for ulnar collateral ligament (UCL) reconstruction, we performed a kinematic study of 15 cadaver elbows. The margins of the anterior and posterior oblique ligaments of the UCL were measured. Five humeral and three ulnar attachment sites were also selected and grouped in pairs for measurement. The distances from the proximal center of the trochlea to three ulnar points were recorded. Measurements were obtained for pairs of attachment sites for flexion of 0 degree, 30 degrees, 60 degrees, 90 degrees, and 120 degrees. We found that the anterior margin of the anterior oblique ligament (AOL) tended to lengthen as flexion increased from 0 degree to 60 degrees, and to shorten as flexion exceeded 60 degrees. The posterior margin tended to lengthen with flexion up to 120 degrees. It therefore appears that the AOL consists of functionally different components that remain taut throughout flexion. In all experiments, the location of the humeral attachment site affected the lengths through 120 degrees of flexion. At flexion of 0 degree-120 degrees, isometricity was observed in the approximate center of the trochlea, apparently the optimal attachment site. We conclude that conventional ligament reconstruction methods that locate the attachment site in the AOL origin provide inadequately for the isometricity observed in the natural anatomy.
The volume of myocardium perfused by coronary arterial branches and cumulative length of the main feeder branches perfusing that volume were measured from multislice computed tomography images of human cadaver hearts with barium sulfate gel injected into the coronary arteries. Previously we have shown in in vivo pig hearts that the relationship between the volume (V), in mL, of perfused myocardium and the length (L), is well conveyed by V = M x 10(-aL) where M is total mass of myocardium perfused by a major epicardial artery and a is constant congruent to 0.01 mm-1. In the nine human hearts studied, this relationship was V = 115 x 10(-0.006L), r = -0.894 for the LAD; V = 48 x 10(-0.009L), r = -0.7663 for the LCX and V = 103 x 10(-0.004L), r = -0.673 for the RCA. These results suggest that the angiographically delineated volume of myocardium at risk of infarction, due to acute blockage along a coronary artery, could possibly be estimated from the 3D branching geometry of the epicardial coronary arterial tree.
We compared semiconductor diode, neodymium (Nd): YAG and argon laser iridectomies performed in 14 cadaver eyes using Miyake videographic, histologic and scanning electron analysis. We found that the diode laser created an iridectomy in < 10 applications in blue, hazel and brown irides using 1000-1200 mW over 0.5 seconds. In hazel and blue irides the argon laser created iridectomies at parameters similar to the diode, but required multiple low energy burns in brown irides. Scanning electron microscopy showed pigment epithelial loss with the diode and Nd:YAG laser, and heaped up epithelium at the iridectomy site with the argon laser. Nd:YAG laser had the greatest iridectomy size. This study suggests a possible clinical advantage of diode versus argon laser iridectomies in reduced applications in brown irides and in preventing postoperative pigment occlusion. However, diode laser demonstrated no definite advantage over Nd:YAG laser.