Inclination Measurements Research Articles

A cadaver study validating CT assessment of acetabular component orientation: the Perth CT hip protocol.

The aim was to develop a CT-based protocol to accurately measure post-operative acetabular cup inclination and anteversion establishing which bony reference points facilitate the most accurate estimation of these variables. An all-polyethylene acetabular liner was implanted into a cadaveric acetabulum. A conventional pelvic CT scan was performed and reformatted images created in both functional and anterior pelvic planes. CT images were transferred to a Freedom-Plus Graphics software package enabling an identical, virtual 3D model of the cadaveric pelvis to be created and definitive acetabular cup orientation established. Using coronal and axial slices of the CT scans, acetabular cup inclination and anteversion were measured on five occasions by ten radiographers using differing predetermined bony landmarks as reference points. The intra- and inter-observer variation in measurement of acetabular cup orientation using varying bony reference points was assessed in comparison to the elucidated definitive cup position. Virtually derived definitive acetabular cup orientation was measured showing cup inclination and anteversion as 41.0 and 22.5° respectively. Mean CT-based measurement of cup inclination and anteversion by ten radiographers were 43.1 and 20.8° respectively. No statistically significant difference was found in intra- and inter-observer recorded results. No statistically significant differences were found when using different bony landmarks. CT assessment of acetabular component inclination and anteversion is accurate, reliable and reproducible when measured using differing bony landmarks as reference points. We recommend measuring acetabular inclination and anteversion from the inferior acetabular wall/teardrop and posterior ischium respectively.

Treatment of Distal Radius Metaphyseal Comminution Fracture by Volar Locking Plate Fixation

Objective: The pronator quadratus (PQ) has important functions such as pronation and robust blood supply of metaphysis. However, PQ repair is difficult when using conventional approach, which is necessary to release PQ for volar plate fixation of distal radius fracture. In addition, anatomical reduction is difficult in patients with distal radius metaphyseal comminution fracture. Therefore, the purpose of this study is to compare the results of volar locking plate fixation using PQ sparing technique and conventional volar approach technique for patients with distal radius metaphyseal comminution fracture. Materials and Methods: In total, 30 patients treated with volar locking plate using PQ sparing approach were compared with 29 patients using conventional approach in distal radius metaphyseal comminution fracture. Mean follow-up periods were 19 and 26 months each. Postoperative clinical evaluation was performed with wrist range of motions, pronation power, and modified Mayo wrist score measured at last follow-up. Radiologic evaluation was performed with mean bone union period and measurement of radial length, radial inclination, and volar tilt at last follow-up. Results: Mean range of motion, pronation power, and modified Mayo wrist score were significantly superior in PQ sparing approach group. Bony union was achieved in all two groups. However, mean bone union period was superior in PQ sparing approach group (8.7 weeks in PQ sparing group vs 12.5 weeks in conventional group). Radial length, radial inclination, and volar tilt did not show significant differences. Conclusion: We propose that a volar locking plate fixation using PQ sparing technique is a more effective treatment method than conventional approach for patients with distal radius metaphyseal comminution fracture.

Volar locking plate (VLP) versus non-locking plate (NLP) in the treatment of die-punch fractures of the distal radius, an observational study

PurposeThis study aims to evaluate whether volar locking plate was superior over non-locking plate in the treatment of die-punch fractures of the distal radius. MethodsA total of 57 patients with closed die-punch fractures of the distal radius were included and analyzed. Of them, 32 were treated by non-locking plate (NLP) and the remaining 25 were treated by volar locking plate (VLP). Preoperative radiographs, computer tomographs and three-dimensional reconstruction, radiographs taken at immediate postoperation and at last follow-up were extracted and evaluated. Patients' electronic medical records were inquired and related demographic and medical data were documented. The documented contents were volar tilt, radial inclination, ulnar variance, grip strength, Disabilities of the Arm, Shoulder, and Hand (DASH) and visual analog scale (VAS) scores and complications. ResultsVLP group demonstrated a significantly reduced radial subsidence of 1.5 mm (0.7 versus 2.2 mm), during the interval of bony union (P < 0.001), compared to NLP group. Larger proportion of patients (88% versus 62.5%) in VLP group gained acceptable joint congruity (step-off <2 mm) at the final follow-up (P = 0.037). No significant differences were observed between the groups in the measurements of volar tilt, radial inclination, DASH, VAS and grip strength recovery at the last follow-up. There was a trend of fewer overall complications (5/25 versus 10/32) and major complications that required surgery interventions (1/25 versus 4/32) in VLP than NLP groups, although the difference did not approach to significance (P = 0.339, 0.372). ConclusionsVLP leaded to significantly better results of reduction maintainance and the final joint congruity than NLP, while reducing overall and major complications. However, the results should be treated in the context of limitations and the clinical significance of the difference required further studies to investigate.

Safety monitoring of underground steel pipeline subjected to soil deformation using wireless inclinometers

Failures occurring in buried pipelines are usually associated with structural damages externally induced by surface loading or permanent ground deformation. In the framework of structural health monitoring, this paper presents a real-time monitoring technique for safety evaluation of continuously welded underground pipelines subjected to soil deformation using dual axis wireless inclinometers. Based on the multiple inclination measurements, a new algorithm combined with indirect adjustment theory and the general solution of the differential equation of beam model on elastic foundation are developed to reconstruct the rotation equation. The deflection curve is then derived to locate the abnormal surface loading and permanent ground deformation. Stress is also calculated to evaluate the performance of the buried pipeline. Numerical simulations verify that the proposed algorithm is of high precision to reconstruct the rotation equation as well as to calculate the deflection and strain. Based on error analysis, comparative studies between the traditional leveling method and the proposed method are conducted and verify the ascendency of the new technique. Field testing on a 24-m-long buried steel pipe equipped with wireless inclinometers is finally carried out and validates the effectiveness to locate the external interference and evaluate the safety of buried pipeline.

Radiographic characterization of the B2 glenoid: the effect of computed tomographic axis orientation

Glenoid retroversion may accelerate glenoid loosening after total shoulder arthroplasty. Accurate measurement of preoperative glenoid deformity is critical for decision-making and prognostication. The purpose of this study was to determine whether glenoid version, inclination, and depth and humeral subluxation measurements on computed tomography (CT) scan slices oriented in the plane of the body differ from those oriented in the scapular plane and those obtained by automated 3-dimensional reconstruction software in the setting of a biconcave B2-type glenoid. Thirty-one preoperative CT scans in patients undergoing total shoulder arthroplasty with Walch B2-type glenoids underwent a standardized measurement protocol by 3 observers. Glenoid version, inclination, and depth and humeral subluxation were measured on 2-dimensional CT images in the plane of the body, on 2-dimensional images in the plane of the scapula, and by a validated, automated 3-dimensional software program. Correction of CT slice axis into the plane of the scapula decreased measured retroversion by 2.4° to 4.7° (P < .004) and inclination by 21° (P < .001). Whereas uncorrected version measurements do not differ from automated software measurements, corrected measurements do (P < .001). Whereas corrected inclination measurements do not differ from automated measurements, uncorrected measurements do (P < .001). Automated measurements differed from both corrected and uncorrected subluxation (P < .001 in both cases). If CT images are not reoriented into the plane of the scapula, version and inclination will be significantly overestimated. In the setting of a retroverted, deformed glenoid, automated software may produce similar inclination measurements to corrected 2-dimensional CT, but it produces significantly altered measurements of version and subluxation.

A CANDIDATE YOUNG MASSIVE PLANET IN ORBIT AROUND THE CLASSICAL T TAURI STAR CI TAU*

ABSTRACT The ∼2 Myr old classical T Tauri star CI Tau shows periodic variability in its radial velocity (RV) variations measured at infrared (IR) and optical wavelengths. We find that these observations are consistent with a massive planet in a ∼9 day period orbit. These results are based on 71 IR RV measurements of this system obtained over five years, and on 26 optical RV measurements obtained over nine years. CI Tau was also observed photometrically in the optical on 34 nights over ∼one month in 2012. The optical RV data alone are inadequate to identify an orbital period, likely the result of star spot and activity-induced noise for this relatively small data set. The infrared RV measurements reveal significant periodicity at ∼9 days. In addition, the full set of optical and IR RV measurements taken together phase coherently and with equal amplitudes to the ∼9 day period. Periodic RV signals can in principle be produced by cool spots, hotspots, and reflection of the stellar spectrum off the inner disk, in addition to resulting from a planetary companion. We have considered each of these and find the planet hypothesis most consistent with the data. The RV amplitude yields an of ∼8.1 M Jup; in conjunction with a 1.3 mm continuum emission measurement of the circumstellar disk inclination from the literature, we find a planet mass of ∼11.3 M Jup, assuming alignment of the planetary orbit with the disk.

Usability of inclinometers as a complementary measurement tool in structural monitoring

In the last few years, many structural monitoring studies have been performed using different techniques to measure structures of different scales such as buildings, dams or bridges. One of the mostly used tools are GPS instruments, which have been utilized in various combinations with accelerometers and some other conventional sensors. In the current study, observation series were recorded for 8 hours with GPS receivers (NovAtel) and Inclination Measurement Sensors mounted on a television tower in Istanbul, Turkey. Each series of observations collected from two different sensors were transformed into a single coordinate system (Local Topocentric Coordinates System). The positional changes of the tower were calculated from the GPS and the inclination data. These changes were plotted in two dimensions (2D) on the same graphic. Thus, the possibility of comparison and analysis were found using the data from both the GPS and the Inclinometer complement each other, in the real test area. The positional changes of the tower were modeled for further examination. As a result, the movement of the tower within an area of <TEX>$1{\times}1cm^2$</TEX> was observed. Based on the results, it can be concluded that inclinometers can be used for monitoring the structural behavior of the tower.

Midterm results of 36 mm metal-on-metal total hip arthroplasty.

Background:Despite the many perceived benefits of metal-on-metal (MoM) articulation in total hip arthroplasty (THA), there have been growing concerns about metallosis and adverse reaction to metal debris (ARMD). Analysis of size 36 mm MoM articulation THAs is presented. These patients were evaluated for patient characteristics, relationship between blood metal ions levels and the inclination as well as the version of acetabular component, cumulative survival probability at final followup and functional outcome at final followup.Materials and Methods:288, size 36 mm MoM THAs implanted in 269 patients at our institution from 2004 to 2010 were included in this retrospective study. These patients were assessed clinically for hip symptoms, perioperative complications and causes of revision arthroplasty were analysed. Biochemically, blood cobalt and chromium metal ions level were recorded and measurements of acetabular inclination and version were examined. Radiological evaluation utilizing Metal Artefact Reduction Sequence (MARS) MRI was undertaken and implant cumulative survivorship was evaluated.Results:The mean followup was 5 years (range 2–7 years), mean age was 73 years and the mean Oxford hip score was 36.9 (range 5–48). Revision arthroplasty was executed in 20 (7.4%) patients, of which 15 patients underwent single-stage revision THA. The causes of revision arthroplasty were: ARMD changes in 6 (2.2%) patients, infection in 5 (1.9%) patients and aseptic loosening in 5 (1.9%) patients. Three (1.1%) patients had their hips revised for instability, 1 (0.3%) for raised blood metal ions levels. The implant cumulative survival rate, with revision for any reason, was 68.9% at 7 years.Conclusions:Although medium-sized MoM THA with a 36 mm head has a marginally better survivorship at midterm followup, compared to larger size head MoM articulating THA, our findings nonetheless are still worryingly poor in comparison to what has been quoted in the literature. Furthermore, ARMD-related revision remains the predominant cause of failure in this cohort with medium-sized MoM articulation. No correlation was found between blood metal ions levels and the inclination as well as the version of acetabular component.

Forehead Inclination in the Lateral Profile in Koreans.

Forehead Inclination in the Lateral Profile in Koreans.

Revealing the broad iron Kαline in Cygnus X-1 through simultaneousXMM-Newton, RXTE, and INTEGRAL observations

We report on the analysis of the broad Fe Kalpha line feature of Cygnus X-1 in the spectra of four simultaneous hard intermediate state observations made with the X-ray Multiple Mirror mission (XMM-Newton), the Rossi X-ray Timing Explorer (RXTE), and the International Gamma-Ray Astrophysics Laboratory (INTEGRAL). The high quality of the XMM-Newton data taken in the Modified Timing Mode of the EPIC-pn camera provides a great opportunity to investigate the broadened Fe Kalpha reflection line at 6.4keV with a very high signal to noise ratio. The 4-500keV energy range is used to constrain the underlying continuum and the reflection at higher energies. We first investigate the data by applying a phenomenological model that consists of the sum of an exponentially cutoff power law and relativistically smeared reflection. Additionally, we apply a more physical approach and model the irradiation of the accretion disk directly from the lamp post geometry. All four observations show consistent values for the black hole parameters with a spin of $a\sim 0.9$, in agreement with recent measurements from reflection and disk continuum fitting. The inclination is found to be $i\sim30^\circ$, consistent with the orbital inclination and different from inclination measurements made during the soft state, which show a higher inclination. We speculate that the difference between the inclination measurements is due to changes in the inner region of the accretion disk.

Comprehensive three-dimensional cone beam computed tomography analysis of the temporomandibular joint in different vertical skeletal facial patterns

BackgroundTo investigate three-dimensionally using cone beam computed tomography (CBCT) imaging the morphological and spatial characteristics of the temporomandibular joints (TMJs) in different vertical skeletal facial patterns. Materials and MethodsSixty adult patients with no signs and symptoms of temporomandibular disorders were divided equally into three groups: skeletal normal vertical face, long face, and short face malocclusions. Bilateral TMJs were evaluated on the CBCT images, and the following three-dimensional measurements were assessed: (1) mandibular fossa position, inclination, and parameters, (2) mandibular condyle position, inclination, and parameters, and (3) circumferential TMJ space measurements. ResultsThe average mandibular plane inclination was 32.77 ± 1.17° for average pattern, 48.33 ± 2.76° for long face, and 27.27 ± 2.30° for short face malocclusion. Long face showed the statistically significant highest glenoid fossa width (18.34 ± 2.20 mm), more lateral positioned condyles, and more anterioposterior condylar joint position. The long face pattern showed the highest mean value of medial joint space. The short face pattern showed the highest glenoid fossa surface area (106.40 ± 14.68 mm2), sagittal condylar surface area (48.47 ± 4.54 mm2), and superior and anterior joint spaces, as well as lowest posterior joint spaces. ConclusionThe TMJ parameters differ between different vertical facial patterns that should be considered when planning an orthodontic case.

Error-Compensation Method for Inclination Measurement Under the Influence of the Dynamic Interference

To deal with the problem of the inclination measurement errors caused by the dynamic motions, such as rotational and accelerated rectilinear components, this paper puts forward an effective inclination measurement scheme and the corresponding error-compensation method based on one accelerometer and two gyroscopes. In addition, the principle prototype of the dynamic inclination measurement apparatus is set up to conduct experiments of turntable rotation test, trolley test, and the turntable sway test at different inclined angles, thus verifying the feasibility of the error-compensation method under the effects of the rotational motion, accelerated rectilinear motion or both motions at the same time. Experimental results show that the aforementioned method can effectively compensate the inclination measurement errors resulting from the rotational and accelerated rectilinear motions.

An Annular Planar-capacitive Tilt Sensor with a 360° Measurement Range

A planar-capacitive tilt sensor with concentric annular electrodes is proposed for further expansion of inclination measurement range. Using dielectric liquid as a sensing pendulum, the proposed sensor can measure the inclination angle of an object with respect to gravity, such as a crane boom or a robot manipulator. The capacitance values of four segmented annular planar capacitors in sensor head vary with the rotation of the object. Such measurement mechanism remains effective even with a 360° rotation. In our lab, a tilt-sensor prototype was assembled with optimized sensor head and suitable dielectric liquid and its performance was evaluated on a tilted plane. Experimental results show that a full measurement range of 360° was achieved with an accuracy of 0.4° and a resolution better than 0.1°. Moreover, the proposed tilt sensor is easy to fabricate, and its components are available at a low cost.

Ductile cutting of silicon microstructures with surface inclination measurement and compensation by using a force sensor integrated single point diamond tool

This paper presents a measurement and compensation method of surface inclination for ductile cutting of silicon microstructures by using a diamond tool with a force sensor based on a four-axis ultra-precision lathe. The X- and Y-directional inclinations of a single crystal silicon workpiece with respect to the X- and Y-motion axes of the lathe slides were measured respectively by employing the diamond tool as a touch-trigger probe, in which the tool-workpiece contact is sensitively detected by monitoring the force sensor output. Based on the measurement results, fabrication of silicon microstructures can be thus carried out directly along the tilted silicon workpiece by compensating the cutting motion axis to be parallel to the silicon surface without time-consuming pre-adjustment of the surface inclination or turning of a flat surface. A diamond tool with a negative rake angle was used in the experiment for superior ductile cutting performance. The measurement precision by using the diamond tool as a touch-trigger probe was investigated. Experiments of surface inclination measurement and ultra-precision ductile cutting of a micro-pillar array and a micro-pyramid array with inclination compensation were carried out respectively to demonstrate the feasibility of the proposed method.

Reliability analysis of glenoid component inclination measurements on postoperative radiographs and computed tomography–based 3D models in total and reversed shoulder arthroplasty patients

Only a few articles describe the reproducibility and clinical feasibility of glenoid inclination measurements on conventional radiographs, and none of them validated their method in shoulder arthroplasty cases. From a clinical point of view, the angle measured between the supraspinatus fossa and the glenoid fossa line (angle β) appears to be the most interesting angle to assess glenoid inclination. This study aimed to validate the angle β in shoulder arthroplasty patients to facilitate the assessment of glenoid component inclination. Seventeen patients who underwent total or reverse shoulder arthroplasty were evaluated. The angle β was measured by 2 independent observers on postoperative radiographs and 3-dimensional (3D) models. The interobserver variability and accuracy of angle β were analyzed by calculating the intraclass correlation coefficient (ICC) and by generating Bland-Altman plots. The angle β showed a good interobserver variability (ICC=0.971 for radiographs, ICC=0.980 for 3D models) and a good agreement between the radiographic and 3D measurements (ICC=0.904 for observer 1 and ICC=0.908 for observer 2). Bland-Altman plots demonstrated that in 95% of the measurements on radiographs, the error will be <10. In the investigated population, 85% showed an error <6. This study demonstrates that angle β can be measured on radiographs to assess glenoid component inclination in total and reverse shoulder arthroplasty, but clinicians and researchers should keep in mind that measurement errors of 10° may occur in a minority of cases.

A randomised controlled trial of cemented and cementless femoral components for metal-on-metal hip resurfacing: a bone mineral density study.

The primary purpose of this study of metal-on-metal (MoM) hip resurfacing was to compare the effect of using a cementless or cemented femoral component on the subsequent bone mineral density (BMD) of the femoral neck. This was a single-centre, prospective, double-blinded control trial which randomised 120 patients (105 men and 15 women) with a mean age of 49.4 years (21 to 68) to receive either a cemented or cementless femoral component. Follow-up was to two years. Outcome measures included total and six-point region-of-interest BMD of the femoral neck, radiological measurements of acetabular inclination, neck-shaft and stem-shaft angles, and functional outcome scores including the Harris hip score, the Western Ontario and McMaster Universities Osteoarthritis Index and the University of California at Los Angeles activity scale. In total, 17 patients were lost to follow-up leaving 103 patients at two years. There were no revisions in the cementless group and three revisions (5%) in the cemented group (two because of hip pain and one for pseudotumour). The total BMD was significantly higher in the cementless group at six months (p < 0.001) and one year (p = 0.01) than in the cemented group, although there was a loss of statistical significance in the difference at two years (p = 0.155). All patient outcomes improved significantly: there were no significant differences between the two groups. The results show better preservation of femoral neck BMD with a cementless femoral component after two years of follow-up. Further investigation is needed to establish whether this translates into improved survivorship.

Extended Tully–Fisher relations using H i stacking

We present a new technique for the statistical evaluation of the Tully-Fisher relation (TFR) using spectral line stacking. This technique has the potential to extend TFR observations to lower masses and higher redshifts than possible through a galaxy-by-galaxy analysis. It further avoids the need for individual galaxy inclination measurements. To quantify the properties of stacked HI emission lines, we consider a simplistic model of galactic disks with analytically expressible line profiles. Using this model, we compare the widths of stacked profiles with those of individual galaxies. We then follow the same procedure using more realistic mock galaxies drawn from the S3-SAX model (a derivative of the Millennium simulation). Remarkably, when stacking the apparent HI lines of galaxies with similar absolute magnitude and random inclinations, the width of the stack is very similar to the width of the deprojected (= corrected for inclination) and dedispersed (= after removal of velocity dispersion) input lines. Therefore, the ratio between the widths of the stack and the deprojected/dedispersed input lines is approximately constant - about 0.93 - with very little dependence on the gas dispersion, galaxy mass, galaxy morphology, and shape of the rotation curve. Finally, we apply our technique to construct a stacked TFR using HIPASS data which already has a well defined TFR based on individual detections. We obtain a B-band TFR with a slope of $-8.5\pm0.4$ and a K-band relation with a slope of $-11.7\pm0.6$ for the HIPASS data set which is consistent with the existing results.

Accurate characterization of the stellar and orbital parameters of the exoplanetary system WASP-33 b from orbital dynamics

By using the most recently published Doppler tomography measurements and accurate theoretical modeling of the oblateness-driven orbital precessions, we tightly constrain some of the physical and orbital parameters of the planetary system hosted by the fast rotating star WASP-33. In particular, the measurements of the orbital inclination $i_{\rm p}$ to the plane of the sky and of the sky-projected spin-orbit misalignment $\lambda$ at two epochs about six years apart allowed for the determination of the longitude of the ascending node $\Omega$ and of the orbital inclination $I$ to the apparent equatorial plane at the same epochs. As a consequence, average rates of change $\dot\Omega_{\rm exp},~\dot I_{\rm exp}$ of this two orbital elements, accurate to a $\approx 10^{-2}~{\rm deg}~{\rm yr}^{-1}$ level, were calculated as well. By comparing them to general theoretical expressions $\dot\Omega_{J_2},~\dot I_{J_2}$ for their precessions induced by an oblate star whose symmetry axis is arbitrarily oriented, we were able to determine the angle $i^{\star}$ between the line of sight the star's spin $S^{\star}$ and its first even zonal harmonic $J_2^{\star}$ obtaining $i^{\star} = 142^{+10}_{-11}~{\rm deg},~J_2^{\star} = (2.1^{+0.8}_{-0.5})\times 10^{-4}.$ As a by-product, the angle between $S^{\star}$ and the orbital angular momentum $L$ is as large as about $\psi \approx 100$ deg $(\psi^{2008} = 99^{+5}_{-4}~{\rm deg},~\psi^{2014} = 103^{+5}_{-4}~{\rm deg})$, and changes at a rate $\dot\psi = 0.7^{+1.5}_{-1.6}~{\rm deg}~{\rm yr}^{-1}$. The predicted general relativistic Lense-Thirring precessions, or the order of $\approx 10^{-3}~{\rm deg}~{\rm yr}^{-1}$, are, at present, about one order of magnitude below the measurability threshold.

Hip Resurfacing Implant Orientation Analysis: A Comparison of a Computer-Added Design Technique and Computed Tomography

BackgroundAccurate acetabular component orientation in hip resurfacing is mandatory. The aim of this study is to analyze if interpretation of pelvic radiographs with computer-added design (CAD) software is comparable to computed tomography (CT) in measurement of acetabular anteversion and inclination of a Birmingham Hip Resurfacing (BHR) hip. MethodsA consecutive series of 49 patients (50 hips) who underwent hip resurfacing arthroplasty between 2005 and 2007 with the BHR system were retrospectively included. The surgical procedure was performed by 1 orthopedic surgeon in the beginning of his learning curve. Computer-added design software was used to measure acetabular component orientation on an anteroposterior pelvic radiograph. These measurements were compared with CT measurements. We calculated the correlation between the CAD software and CT analysis. The degree of underestimation or overestimation was determined, and a Bland-Altman plot was created to visualize the agreement between CAD software and CT results. ResultsWe analyzed 50 BHR hips with mean inclination of 54.6° and 55.6° and mean anteversion of 24.8° and 13.3° measured by CT and CAD, respectively. Pearson correlation coefficient for inclination was 0.69 (P < .001) and for anteversion 0.81 (P < .001). Computer-added design showed a mean underestimated anteversion of 11.6° (P < .001). There was no significant underestimation or overestimation of inclination with CAD analysis compared to CT measurements. ConclusionThe CAD software is useful to assess acetabular inclination in hip resurfacing but underestimates anteversion.

Correlation between glenoid inclination and critical shoulder angle: a radiographic and computed tomography study

Increased critical shoulder angles consist of both the acromial cover and glenoid inclination and have been found in patients with rotator cuff pathology. The purpose of this study was to determine the correlation of the critical shoulder angle and glenoid inclination and to determine the difference in glenoid inclination between patients with osteoarthritis and massive rotator cuff tears. The critical shoulder angle and glenoid inclination were measured on anteroposterior radiographs, and glenoid inclination was also measured on a validated 3-dimensional computer software program of 50 shoulders undergoing primary total shoulder arthroplasty. Twenty-five shoulders had osteoarthritis and A1 glenoids, as defined by the Walch classification, and were undergoing anatomic shoulder arthroplasty. The other 25 shoulders had massive rotator cuff tears and E0 glenoids, as defined by the Favard classification. The 2 groups were compared. Critical shoulder angle and glenoid inclination were significantly correlated (R(2) = 0.7426, P < .001). Shoulders with massive rotator cuff tears (E0) demonstrated increased glenoid inclination measurements than shoulders with osteoarthritis (A1). As measured by the 3-dimensional software, the massive rotator cuff group had a glenoid inclination of 13.6° ± 4.3° and the osteoarthritis group had a glenoid inclination of 4.7° ± 5.6°. When measured by anteroposterior radiographs, the average glenoid inclination was 13.6° ± 4.6° in the massive rotator cuff group and was 7.6° ± 5.01° in the osteoarthritic group . Glenoid inclination is linearly correlated with the critical shoulder angle and is significantly increased in patients with massive rotator cuff tears.