Risk analysis of tunnel collision in combined anterior cruciate ligament and anterolateral ligament reconstructions.

BACKGROUND: To assess the risk of tunnel collision in combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstructions. METHODS: Three-dimensional (3D) CT reconstructions of 32 knees after transtibial (TT) (N = 16) or anteromedial portal (AMP) (N = 16) ACL reconstruction were used to simulate potential tunnel collision of the femoral ACL tunnel if combined with a virtual ALL reconstruction. The minimal distance between tunnels, the ALL tunnel length, and the lateral femoral condyle (LFC) width were measured. Moreover, the relationship between the ALL tunnel and the intercondylar notch, trochlear groove and posterior femoral cortex was determined. RESULTS: The highest rate of tunnel collision (81%) was observed when the ALL tunnel was aimed at 20° in the coronal plane and 0° in the axial plane. However, by aiming the ALL tunnel at 0° coronal and 40° axial angulation, collision was avoided in all patients and no violation of the trochlea was observed. Tunnel collision rate was significantly higher (P = 0.002) when the ACL tunnel was drilled by the AMP technique. CONCLUSIONS: Risk of tunnel collision was significantly increased when the tunnel was drilled at 0° in the axial plane. Tunnel collision was avoided by aiming the ALL tunnel 40° anteriorly and perpendicular to the anatomical axis of the femur. A more horizontal orientation of the ACL with the AMP technique is a risk factor for tunnel conflicts. CLINICAL RELEVANCE: ALL tunnel orientation needs to be adjusted to avoid tunnel conflicts in combined ACL-ALL reconstructions.

Transportal femoral drilling creates more horizontal ACL graft orientation compared to transtibial drilling: A 3D CT imaging study.

BACKGROUND: The principle of anatomic anterior cruciate ligament (ACL) reconstruction is to create a femoral and tibial tunnel that resembles the insertion of the native ACL. Anatomic reconstruction leads to a more horizontal graft orientation that provides more rotational stability. The aim of this study is to investigate the best method to achieve anatomical reconstruction of femoral insertion of the ACL and thus, a more horizontal orientation of the ACL. We compared tunnel position and orientation between transportal femoral drilling technique and transtibial technique. METHODS: Thirty-two patients were included. Post-operative CT scans were obtained and femur, tibia and ACL tunnels were reconstructed. The position and orientation of tibial and femoral tunnels were quantified using the quadrant method, and femoral tunnel length, ellipticity and posterior wall breakage were assessed. We also investigated clinical outcome. RESULTS: Analyses show that transportal drilled femoral tunnels were situated significantly lower than transtibial drilled tunnels (p<0.0001), resulting in a significantly more horizontal oriented ACL in the transportal group in coronal (p<0.0001) and sagittal plane (p=0.01). No differences were observed in depth of femoral tunnel position (p=0.44). Femoral tunnel length was shorter in the transportal group (p=0.01) with a more ellipsoidal femoral aperture (p=0.01). There were no differences between both groups in tibial position. There were no differences in clinical outcome measure between the transportal and transtibial groups. CONCLUSION: This study indicates that transportal drilling of the femoral tunnel leads to a more horizontal graft orientation of the ACL, without differences in clinical outcome.

A statistical shape model of trochlear dysplasia of the knee.

BACKGROUND: Trochlear dysplasia is known as the primary predisposing factor for patellar dislocation. Current methods to describe trochlear dysplasia are mainly qualitative or based on a limited number of discrete measurements. The purpose of this study is to apply statistical shape analysis to take the full geometrical complexity of trochlear dysplasia into account. METHODS: Statistical shape analysis was applied to 20 normal and 20 trochlear dysplastic distal femur models, including the cartilage. RESULTS: This study showed that the trochlea was anteriorized, proximalized and lateralized and that the mediolateral width and the notch width were decreased in the trochlear dysplastic femur compared to the normal femur. The first three principal components of the trochlear dysplastic femurs, accounting for 79.7% of the total variation, were size, sulcus angle and notch width. Automated classification of the trochlear dysplastic and normal femora achieved a sensitivity of 85% and a specificity of 95%. CONCLUSIONS: This study shows that shape analysis is an outstanding method to visualise the location and magnitude of shape abnormalities. Improvement of automated classification and subtyping within the trochlear dysplastic group are expected when larger training sets are used. CLINICAL RELEVANCE: Classification of trochlear dysplasia, especially borderline cases may be facilitated by automated classification. Furthermore, the identification of a decreased notch width in association with an increased sulcus angle can also contribute to the diagnosis of trochlear dysplasia.

Automated extraction of the femoral anatomical axis for determining the intramedullary rod parameters in total knee arthroplasty.

The automated extraction of anatomical reference parameters may improve speed, precision and accuracy of surgical procedures. In this study, an automated method for extracting the femoral anatomical axis (FAA) from a 3D surface mesh, based on geometrical entity fitting, is presented. This was applied to conventional total knee arthroplasty, which uses an intramedullary rod (FIR) to orient the femoral prosthesis with respect to the FAA. The orientation and entry point of a FIR with a length of 200 mm are automatically determined from the FAA, as it has been shown that errors in these parameters may lead to malalignment of the mechanical axis. Moreover, the effect of partially scanning the leg was investigated by creating reduced femur models and comparing the results with the full models. Precise measurements are obtained for 50 models by using a central and two outer parts, with lengths of 20 and 120 mm, which correspond to 58% of the mean femoral length. The deviations were less than 2 mm for the FAA, 2.8 mm for the FAA endpoints and 0.7° and 1.3 mm for the FIR orientation and entry point. The computer-based techniques might eventually be used for preoperative planning of total knee arthroplasty.

PYY(3-36) induces Fos in the arcuate nucleus and in both catecholaminergic and non-catecholaminergic neurons in the nucleus tractus solitarius of rats.

Peptide YY (3-36) [PYY(3-36)] inhibits feeding in rodents, nonhuman primates and humans, yet the neural circuits underlying this action remain to be determined. Here we assessed whether PYY(3-36) inhibits feeding by activating neurons in forebrain and hindbrain sites containing Y2 receptors and linked to control of food intake, or in hindbrain sites immediately downstream of vagal afferent neurons. Rats received an anorexigenic dose of PYY(3-36), and the number of neurons expressing Fos, an indicator of neuronal activation, was determined in anterior hypothalamus (AH), arcuate nucleus (ARC), dorsomedial hypothalamus (DMH), lateral hypothalamus (LH), ventromedial hypothalamus (VMH), central nucleus of the amygdala (CeA), area postrema (AP), and caudal medial nucleus tractus solitarius (cmNTS), commissural NTS (cNTS), and gelatinosus NTS (gNTS). Expression of tyrosine hydroxylase (TH), an indicator of catecholamine synthesis, was also measured in the cmNTS. PYY(3-36) increased Fos in ARC, cmNTS, gNTS and AP. Approximately 10% of Fos+ neurons in the cmNTS were TH+. These results suggest that PYY(3-36) inhibits feeding through direct activation of ARC neurons, and direct and/or indirect activation via vagal afferent nerves of cmNTS, gNTS and AP, including some catecholaminergic neurons in the cmNTS.

Elucidation of reaction scheme describing malondialdehyde-acetaldehyde-protein adduct formation.

Malondialdehyde and acetaldehyde react together with proteins and form hybrid protein conjugates designated as MAA adducts, which have been detected in livers of ethanol-fed animals. Our previous studies have shown that MAA adducts are comprised of two distinct products. One adduct is composed of two molecules of malondialdehyde and one molecule of acetaldehyde and was identified as the 4-methyl-1,4-dihydropyridine-3,5-dicarbaldehyde derivative of an amino group (MDHDC adduct). The other adduct is a 1:1 adduct of malondialdehyde and acetaldehyde and was identified as the 2-formyl-3-(alkylamino)butanal derivative of an amino group (FAAB adduct). In this study, information on the mechanism of MAA adduct formation was obtained, focusing on whether the FAAB adduct serves as a precursor for the MDHDC adduct. Upon the basis of chemical analysis and NMR spectroscopy, two initial reaction steps appear to be a prerequisite for MDHDC formation. One step involves the reaction of one molecule of malondialdehyde and one of acetaldehyde with an amino group of a protein to form the FAAB product, while the other step involves the generation of a malondialdehyde-enamine. It appears that generation of the MDHDC adduct requires the FAAB moiety to be transferred to the nitrogen of the MDA-enamine. For efficient reaction of FAAB with the enamine to take place, additional experiments indicated that these two intermediates likely must be in positions on the protein of close proximity to each other. Further studies showed that the incubation of liver proteins from ethanol-fed rats with MDA resulted in a marked generation of MDHDC adducts, indicating the presence of a pool of FAAB adducts in the liver of ethanol-fed animals. Overall, these findings show that MDHDC-protein adduct formation occurs via the reaction of the FAAB moiety with a malondialdehyde-enamine, and further suggest that a similar mechanism may be operative in vivo in the liver during prolonged ethanol consumption.

Relevance of CagA positivity to clinical course of Helicobacter pylori infection in children.

A potential virulence determinant of Helicobacter pylori is the cagA gene product. To determine the relevance of the expression of CagA to the clinical picture and outcome of H. pylori infection in children, we examined 104 consecutive children diagnosed with H. pylori infection. Serum samples were collected to test for the presence of immunoglobulin G (IgG) anti-CagA antibodies. Forty-five patients (43%) had antibodies to the CagA protein (group I), and 59 did not (group II). Seropositive patients had a longer prediagnostic history of abdominal pain (P = 0.02), more severe abdominal pain (defined as ulcer pain) (P = 0.05), a higher prevalence of duodenal ulcer (38 versus 7%; P<0.01), more active chronic gastritis (82 versus 32%; P<0.001), and a higher titer of serum IgG anti-H. pylori antibodies (P<0.001). Ninety percent of the patients were monitored for 27+/-18 months. On multivariate analysis, CagA-negative patients had a 3.8-fold-higher chance of achieving a disease-free state than CagA-positive patients (95% confidence interval, 1.5- to 9.5-fold). We conclude that infection with CagA-producing strains of H. pylori is a risk factor for severe clinical disease and ongoing infection.