Anterolateral ligament of the knee: myth or reality?

PURPOSE: A ligament of the knee has recently drawn the attention: the rediscovered anterolateral ligament (ALL) of the knee. The tibial insertion of the ALL is torn off in the Segond fracture, pathognomonic of the anterior cruciate ligament tear. The ALL originates from the lateral femoral epicondyle and has fibers inserting on the lateral meniscus. It attaches distally to the tibial plateau, midway between the tip of the fibular head and Gerdy's tubercle. The purpose of this study was to evaluate the visibility of the ALL using routine MRI (1.5T) protocol. MATERIALS AND METHODS: In the first part of our study 10 cadaveric knee joints were examined using MR imaging to evaluate the visibility of the ALL. These cadaveric knees have been dissected to assess the presence of the ALL and to evaluate the accordance between MRI and anatomic dissection. In the second part of the study, 61 knee MRI of patients were examined to evaluate the visibility of the ALL using axial and coronal DP-FS weighted sequences. RESULTS: In all cadaveric knee MRI, the ALL was visualized (full visualization in 75 % and partial visualization in 25 % of the cases), with 100 % accordance between MRI and anatomic dissection. Two cadaveric knees where the ALL was not viewed were excluded of the radio-anatomic analysis. The ALL was visualized in 93.4 % (95 % CI = 84.1-98.2) of the knee MRI studies of the 61 patients included. The whole ligament was visualized in 82 % (95 % CI = 70-90.6) examinations and it was partially visualized in 11.5 % (95 % CI = 4.7-22.2). CONCLUSION: Our results show that the ALL of the knee can be identified using routine 1.5T MR imaging, which suggest that better radiological description of this underestimated anatomical structure may be beneficial in the preoperative planning of ACL tears.

Fourier Transform Spectroscopy of the O(2) Herzberg Bands. III. Absorption Cross Sections of the Collision-Induced Bands and of the Herzberg Continuum.

Absorption spectra of molecular oxygen were measured in the laboratory under temperature and pressure conditions prevailing in the Earth's atmosphere. Spectra of pure O(2), O(2) + N(2), and O(2) + Ar were recorded in the 41 700 to 33 000 cm(-1) region (240-300 nm) at a maximal optical path difference of 0.45 cm using a Fourier transform spectrometer and a multiple reflection gas cell. The different components of the spectra, namely the discrete bands of the three Herzberg systems, the Herzberg continuum, and the collision-induced diffuse Wulf bands, were separated. The contribution of the Herzberg bands was first subtracted using the line parameters determined previously [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] from high-resolution data. Spectra recorded at various pressures then made it possible to determine by linear regression the intensity of the Wulf bands and the Herzberg continuum. The characteristics of the Wulf bands have been investigated in details: vibrational analysis, pressure effect, foreign gas effect, and a simulated spectrum are reported. The Herzberg continuum cross section is determined below the dissociation limit. A comparison with literature data is given. The new O(2) absorption cross sections and O(2)-O(2) collision-induced absorption cross sections are useful in connection with atmospheric measurements of ozone and other trace gases in the UV spectral region. Copyright 2000 Academic Press.

Fourier Transform Spectroscopy of the O(2) Herzberg Bands.

From absorption spectra obtained at high resolution by coupling a Fourier transform spectrometer to a long-path multiple reflection cell [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] the intensities of the O(2) Herzberg bands (A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), A'( 3)Delta(u)-X(3)Sigma(-)(g)) have been studied at ambient temperature. The integrated cross section values are given for the lines of the (v'-0) bands in the A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), and A'( 3)Delta(u)-X(3)Sigma(-)(g) transitions with v' = 0-11, v' = 2-19, and v' = 2-12, respectively. The band oscillator strengths have been deduced and transition moments have been calculated. The total absorption values in the region of the Herzberg bands together with the photoabsorption values determined previously above the dissociation limit can be modeled by a single curve, in agreement with the continuity relationship of the cross sections through the dissociation limit. Copyright 2000 Academic Press.

Fourier Transform Spectroscopy of the O(2) Herzberg Bands.

The absorption spectra of the O(2) Herzberg band systems (A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), and A' (3)Delta(u)-X(3)Sigma(-)(g)) lying in the wavelength region 240-300 nm were reinvestigated. The coupling of a long absorption cell and a high-resolution Fourier transform spectrometer has allowed the observation of numerous weak lines which were not reported previously. From the rotational analysis of the line positions, determined with an accuracy of 0.005 cm(-1), the molecular constants of the A(3)Sigma(+)(u), v = 0-12, c(1)Sigma(-)(u), v = 2-19, and A' (3)Delta(u), v = 2-12 levels are improved significantly. The interaction between the A and c states is described quantitatively. A new interpretation of the perturbations observed in the energy region close to the dissociation limit is given which involves a weakly bound (3)Pi(u) state as the most probable perturbing state. Copyright 1999 Academic Press.

Absorption cross-sections of atmospheric constituents: NO2, O2, and H2O.

Absorption spectroscopy, which is widely used for concentration measurements of tropospheric and stratospheric compounds, requires precise values of the absorption cross-sections of the measured species. NO(2), O(2) and its collision-induced absorption spectrum, and H(2)O absorption cross-sections have been measured at temperature and pressure conditions prevailing in the Earth's atmosphere. Corrections to the generally accepted analysis procedures used to resolve the convolution problem are also proposed.