Version Angle Research Articles

Is there an association between glenoid parameters and rotator cuff tears and the influence of gender: A retrospective study on a Middle Eastern population

ObjectiveThis study aims to investigate the presence of any differences between the normal population and patients with rotator cuff tears in term of glenoid morphological parameters. MethodFor the purpose of this study, 82 shoulder MRIs were evaluated. The individuals included in this study were divided into the patient group (cuff tear group, n = 41) and the control group (control group, n = 41) with respect to the inclusion and exclusion criteria. For the statistical analysis, SPSS software was used. ResultsStatistically significant difference was found between the patient group and the control group in terms of Glenoid Version Angle (GVA), Glenoid Axial Width (GAW), Glenoid Axial Depth (GAD), Glenoid Coronal Depth (GCD), and the Glenoid Inclination Angle (GIA). Age was found to have a positive linear correlation with the glenoid coronal height. Moreover, statistically significant difference was found between the males and females, between males with cuff tears and control males, and females with cuff tears and control females in terms of glenoid parameters. When gender was a covariate, statistically significant differences in glenoid parameters was still present between cuff tears patients and individuals with control shoulders. ConclusionThe results attained in this study are suggest that the GVA, GAW, GAD, GCD, and GIA in rotator cuff tear patients are different than those found in control patients. These measurements may be helpful in reaching the diagnosis in cases where the clinical diagnosis is equivocal. Moreover, these measurements may be helpful in planning tears management. The influence of gender on glenoid parameters and subsequent impact on shoulder pathology may help to better understand the biomechanism of rotator cuff tears and reach an individualized management for better patient care.

Clinical application of intraoperative O-arm navigation in reverse shoulder arthroplasty

BackgroundInaccurate fixation and positioning of the glenoid component using conventional techniques are problematic in reversed shoulder arthroplasty (RSA). Our objective was to investigate the accuracy of O-arm navigation of the glenoid component in RSA. MethodsThis retrospective case–control study comprised 2 groups of 25 patients who underwent reversed shoulder arthroplasty with or without intraoperative O-arm navigation. The intraoperative goal was to place the component neutrally in the glenoid in the axial plane and 10° inferiorly tilted in the scapular plane. Glenoid version angle and inclination were measured by computed tomography obtained preoperatively and a year postoperatively. Operative time, intraoperative bleeding, and the presence of postoperative complications were recorded. ResultsCompared with the ideal, the range of error for version was 7.3° (SD 3.6°) in the control group and 5.6° (SD 3.6°) in the navigated group (P = 0.278), and the range of error for inclination was 18.3° (SD 11.7°) in the control group and 4.9° (SD 3.8°) in the navigated group (P = 0.0004). The mean operative time was 164.6 (SD 21.2) min in the control group and 192.0 (SD 16.2) min in the navigated group (P = 0.001). The mean intraoperative bleeding was 201.0 (SD 37.0) mL in the control group and 185.3 (SD 35.6) mL in the navigated group (P = 0.300). There were no complications reported related to the intraoperative O-arm navigation. ConclusionO-arm navigation may be a useful tool for the placement with inferior tilt of the glenoid procedure in reversed shoulder arthroplasty.

Misperception of motion in depth originates from an incomplete transformation of retinal signals.

Depth perception requires the use of an internal model of the eye-head geometry to infer distance from binocular retinal images and extraretinal 3D eye-head information, particularly ocular vergence. Similarly, for motion in depth perception, gaze angle is required to correctly interpret the spatial direction of motion from retinal images; however, it is unknown whether the brain can make adequate use of extraretinal version and vergence information to correctly transform binocular retinal motion into 3D spatial coordinates. Here we tested this hypothesis by asking participants to reconstruct the spatial trajectory of an isolated disparity stimulus moving in depth either peri-foveally or peripherally while participants' gaze was oriented at different vergence and version angles. We found large systematic errors in the perceived motion trajectory that reflected an intermediate reference frame between a purely retinal interpretation of binocular retinal motion (not accounting for veridical vergence and version) and the spatially correct motion. We quantify these errors with a 3D reference frame model accounting for target, eye, and head position upon motion percept encoding. This model could capture the behavior well, revealing that participants tended to underestimate their version by up to 17%, overestimate their vergence by up to 22%, and underestimate the overall change in retinal disparity by up to 64%, and that the use of extraretinal information depended on retinal eccentricity. Since such large perceptual errors are not observed in everyday viewing, we suggest that both monocular retinal cues and binocular extraretinal signals are required for accurate real-world motion in depth perception.

Is the version angle of the glenoid different in bone and cartilage? An MRI study

Background/aimTo determine whether or not there is a difference between the version of the bone and cartilage surfaces of the glenoid. Axial magnetic resonance imaging (MRI) slices were examined in order to evaluate the measurements taken based on both the cartilage and bone joint surfaces.Materials and methodsA retrospective evaluation was made of the MRI scans of 182 patients. All of the reviewers independently measured the glenoid version angles of all of the patients from 1–182. The process was then repeated, with each reviewer taking second measurements of the angles from 1–182. Pearson correlation coefficient analysis was applied to evaluate the interaction and relationships between the measurements taken from the bone and cartilage. The intra- and interobserver interclass correlation coefficients (ICCs) were assessed. Analysis of variance was applied to determine any interobserver significant differences.ResultsThe mean glenoid version was determined as –3.58 ± 4.08° in the bone-based measurements and –5.81 ± 4.30° in the cartilage-based measurements. The cartilage- and bone-based measurements were found to have inter- and intraobserver reliability. A statistically significant difference was observed between the mean cartilage-based version and the mean bone-based version. Changes in the cartilage- and bone-based measurements were correlated; however, this change was not linear.ConclusionThe cartilage-based version showed a significant difference from the bone- based version. Therefore, in the preoperative planning and evaluation of glenoid-based pathologies, it would be more appropriate to evaluate both the bone and cartilage surface on MRI.

Total hip arthroplasty to address chronic hip luxation with pseudoacetabulum formation in seven dogs.

To compare the outcome of dogs treated with total hip arthroplasty (THA) for chronic hip luxation and pseudoacetabulum formation to that of dogs with simple hip dysplasia and secondary osteoarthritis. Retrospective, case-controlled study. Seven dogs with pseudoacetabulum (group 1) and 21 matched control dogs (group 2). Each dog in group 1 was matched with three control dogs, primarily according to similarity of THA implant type and size. Patterns of radiographic pathology were characterized in each dog. Outcome measures included operative time, acetabular cup position/orientation (inclination angle, angle of lateral opening, version angle) complications, and long-term outcomes. Outcome measures were compared between groups using linear regression (P = .05). The presence of a pseudoacetabulum was associated with ilial remodeling and heterotopic bone formation concentric to the luxated femoral head. Exposing the native acetabulum and reducing the prosthesis were surgically challenging. The mean (SD) operative time of dogs in group 1 (96 [18] minutes) was longer than that of dogs in group 2 (63 [14] minutes; P = .00002). Cup position/orientation was not different between dogs in group 1 and group 2. One intraoperative complication and two minor postoperative complications occurred in group 1 dogs. All dogs had good long-term outcomes. Total hip arthroplasty in dogs with a pseudoacetabulum was more challenging than in control dogs. However, the procedure provided good to excellent long-term clinical outcomes in all dogs. Surgeons should be prepared for the specific surgical challenges associated with THA in dogs with pseudoacetabulum formation.

Is Femoral Version Associated with Changes in Hip Muscle Strength in Females with Symptomatic Femoroacetabular Impingement?

Objective The aim of the present study was to evaluate the association between femoral anteversion and hip muscle strength in subjects with femoroacetabular impingement syndrome. Method The femoral version angles described in the arthro-magnetic resonance images and isokinetic tests were retrospectively evaluated from July 2016 to December 2017. The inclusion criteria were: a) femoral version evaluated by the same radiologist; b) α angle ≥ 55°; and c) no limiting pain during the isokinetic test. Flexion/extension, abduction/adduction, and internal/external rotation peak torques were evaluated at 30° per second in 5 repetitions. The correlation between femoral version and muscle strength was evaluated by simple linear regression at a 5% significance level. Results A total of 37 females filled the inclusion criteria, and 51 symptomatic hips were evaluated. There was no correlation of the femoral anteversion in the flexion, extension, abduction, adduction, external rotation and internal rotation peak torques. Conclusion Femoral anteversion did not show a correlation with hip muscle strength in females with symptomatic femoroacetabular impingement.

Glenoid retroversion is an important factor for humeral head centration and the biomechanics of posterior shoulder stability.

Glenoid retroversion is a known independent risk factor for recurrent posterior instability. The purpose was to investigate progressive angles of glenoid retroversion and their influence on humeral head centration and posterior translation with intact, detached, and repaired posterior labrum in a cadaveric human shoulder model. A total of 10 fresh-frozen human cadaveric shoulders were investigated for this study. After CT- canning, the glenoids were aligned parallel to the floor, with the capsule intact, and the humerus was fixed in 60° of abduction and neutral rotation. Version of the glenoid was created after wedge resection from posterior and fixed with an external fixator throughout the testing. Specimens underwent three conditions: intact, detached, and repaired posterior labrum, while version of the glenoid was set from + 5° anteversion to - 25° retroversion by 5° increments. Within the biomechanical setup, the glenohumeral joint was axially loaded (22N) to center the joint. At 0° of glenoid version and intact labrum, the initial position was used as baseline and served as point zero of centerization. After cyclic preloading, posterior translation force (20N) was then applied by a material testing machine, while start and endpoints of the scapula placed on an X-Y table were measured. The decentralization of the humeral head at glenoid version angles of 5°, 10°, 15°, and 20° of retroversion and 5° of anteversion was significantly different (P < 0.001). Every increment of 5° of retroversion led to an additional decentralization of the humeral head overall by (average ± SD) 2.0mm ± 0.3 in the intact and 2.0mm ± 0.7 in the detached labrum condition. The repaired showed significantly lower posterior translation compared to the intact condition at 10° (P = 0.012) and 15° (P < 0.01) of retroversion. In addition, CT measured parameters (depth, diameter, and native version) of the glenoid showed no correlation with angle of dislocation of each specimen. Bony alignment in terms of glenoid retroversion angle plays an important role in joint centration and posterior translation, especially in retroversion angles greater than 10°. Isolated posterior labrum repair has a significant effect on posterior translation in glenoid retroversion angles of 5° and 10°. Bony correction of glenoid version may be considered to address posterior shoulder instability with retroversion > 15°.

Preoperative multislice computed tomography evaluation of shoulder deformities in brachial plexus birth palsy patients undergoing tendon transfer

BackgroundBrachial plexus birth palsy (BPBP) refers to a birth related paralysis of the upper extremity. The current study was designed to evaluate the efficacy of computed tomography (CT) in the assessment of humeral head posterior subluxation and glenoid retroversion preoperatively and to evaluate whether or not bony deformity correlates with functional improvement (based on Modified Mallet Score) following tendon transfer in brachial plexus birth palsy patients. Patients and methodsThis prospective study included 30 patients, 15 below 4 years and 15 above 4 years old, with a mean age 3.65 ± 1.39 (range 2–8) years old. Thirteen patients were males (43.3%) and 17 were females (56.6%). The left side was affected in 13 patients (43.3%), while the right in 17 (56.7%). The Modified Mallet Score was used for clinical assessment of the shoulder function. A multislice CT scan with 3D reconstruction was used as a preoperative radiological assessment of the shoulder. An electromyography (EMG) of the muscles around the shoulder was performed. All patients were operated upon by anterior release of the internal rotators to improve the external rotation range of motion and by transfer of teres major and latissimus dorsi to improve the abduction motion through one anterior deltopectoral incision and a small posterosuperior incision. Postoperatively, the range of shoulder abduction and external rotation had been assessed after shoulder spica removal and till the end of follow up. ResultsFourteen patients (46.7%) had a normal glenoid version angle (normal range from −12° to 2°) and normal range of articulation with the glenoid (42.3%–71.4%) and 16 patients (53.3%) had an abnormal glenoid version angle and abnormal range of articulation with the glenoid. According to the Modified Mallet Score, there was a statistically significant difference in the mean value of global abduction (P = 0.04), external rotation (P = 0.03), hand to mouth (P = 0.02), hand to neck (P = 0.03) and hand to spine (P = 0.02) between the pre- and post-operative assessment of all patients. There was a statistically significant difference in the mean value of postoperative Modified Mallet Score between the patients under the age of 4 years and those above the age of 4 years. There was no statistically significant difference between the patients with normal CT angles and those with abnormal CT angles. There was no statistically significant difference in the mean value of glenoid version angle and percentage of humeral head articulation between the patients below the age of 4 years and those above 4 years (P = 0.845). ConclusionThe study concluded that the glenoid version angle and humeral head articulation percentage do not negatively affect results of the tendon transfer around the shoulder in patients of upper brachial plexus birth palsy. Level of evidenceIV.

Patient-specific Guides Using 3-dimensional Reconstruction Provide Accuracy and Reproducibility in Reverse Total Shoulder Arthroplasty

BackgroundWe aimed to evaluate whether the use of our novel patient-specific guide (PSG) with 3-dimensional reconstruction in reverse total shoulder arthroplasty (RTSA) would allow accurate and reliable implantation of the glenoid and humeral components.Methods20 fresh-frozen cadaveric shoulders were used. The PSG group (n=10) and conventional group (n=10) was evaluated the accuracy and reproducibility of implant positioning between before and after surgery on the computed tomography image.ResultsThe superoinferior and anteroposterior offset in the glenoid component were 0.42 ± 0.07, 0.50 ± 0.08 in the conventional group and 0.45 ± 0.03, 0.46 ± 0.02 in the PSG group. The inclination and version angles were -1.93° ± 4.31°, 2.27° ± 5.91° and 0.46° ± 0.02°, 3.38° ± 2.79°. The standard deviation showed a smaller difference in the PSG group. The anteroposterior and lateromedial humeral canal center offset in the humeral component were 0.45 ± 0.12, 0.48 ± 0.15 in the conventional group and 0.46 ± 0.59 (p=0.794), 0.46 ± 0.06 (p=0.702) in the PSG group. The PSG showed significantly better humeral stem alignment.ConclusionsThe use of PSGs with 3-dimensional reconstruction reduces variabilities in glenoid and humerus component positions and prevents extreme positioning errors in RTSA.

Computational analysis of glenohumeral joint growth and morphology following a brachial plexus birth injury

Children affected with brachial plexus birth injury (BPBI) undergo muscle paralysis. About 33% of affected children experience permanent osseous deformities of the glenohumeral joint. Recent evidence suggests that some cases experience restricted muscle longitudinal growth in addition to paralysis and reduced range of motion at the shoulder and elbow. It is unknown whether altered loading due to paralysis, muscle growth restriction and contracture, or static loading due to disuse is the primary driver of joint deformity after BPBI. This study uses a computational framework integrating finite element analysis and musculoskeletal modeling to examine the mechanical factors contributing to changes in bone growth and morphometry following BPBI. Simulations of 8 weeks of glenohumeral growth in a rat model of BPBI predicted that static loading of the joint is primarily responsible for joint deformation consistent with experimental measures of bone morphology, whereas dynamic loads resulted in normal bone growth. Under dynamic loading, glenoid version angle (GVA), glenoid inclination angle (GIA), and glenoid radius of curvature (GRC) (−1.3°, 38.2°, 2.5 mm respectively) were similar to the baseline values (−1.8°, −38°, 2.1 mm respectively). In the static case with unrestricted muscle growth, these measures increased in magnitude (5.2°, −48°, 3.5 mm respectively). More severe joint deformations were observed in GIA and GRC when muscle growth was restricted (GVA: 3.6°, GIA: −55°, GRC: 4.0 mm). Predicted morphology was consistent with literature reports of in vivo glenoid morphology following postganglionic BPBI. This growth model provides a framework for understanding the most influential mechanical factors driving glenohumeral deformity following BPBI.

Rotator cuff tears reparability index based on pre-operative MRI: our experience.

Background and aim of the work: It is recognised that a significant percetage of large and massive rotator cuff tears (RCT) cannot be anatomically repaired and this correlates with a worste outcome in terms of pain, active range of motion, increased incidence of retair. The aim of our work is to find reliable index on pre-operative MRI shoulder image to assist orthopaedist in surgical planning of rotatator cuff tears repair. Methods: We performed a retrospective study on a population on 131 patients undergoing arthroscopic cuff repair by a single expert surgeon. Pre-operative MRI images were evaluated by a single orthopaedist, trained on MRI shoulder images ad blinded to surgical outcome. For each magnetic resonance we evaluated the following 9 parameters: fatty Infiltration (FI), Patte Stage (PS), tear size measured in medial-lateral (ML) and anterior-posterior (AP) dimension, Tangent Sign (TS), Occupation Grade (OG), Acromion-Humeral Distance (AHD), Inferior Gleno-Humeral Distance (IGHD), Glenoid Version Angle (GVA). We divided population into two groups: patients who obtained a complete repair of RCT (n=110) and patients who obtained only a partial repair of RCT (n=21). For each MRI index we conducted statistical analysis (Student’s t test, Mann-Whitney U test, Shapiro-Wilk test, Chi-square test, Fisher exact test, ROC curves and maximum Youden index) to find a Cut Off value useful to predict partial repair. Results: We have found statistical significance in predicting partial repair on MRI mesurements of Fatty Infiltration (FI grade ≥3; test di Fisher p<0.001), Patte Stage (grade= 3; test di Fisher p<0.001), Tear size measured in ML (>36 mm; Mann-Whitney p<0.001), Positive Tangent Sign (Chi-quadro p<0.001; sensitivity 95,3%, specificity 83,6%), Occupation Grade (OG <0,46; t-test p<0.001). Acromion-Humeral Distance (AHD <7 mm), Inferior Gleno-Humeral Distance (IGHD >5 mm). Tear size measured in AP (>21 mm; Mann-Whitney p<0.001) seems to be dependent on the contextual size of the lesion in ML. We haven’t found statistical significance in predicting partial repair of Glenoid Version Angle. Conclusions: A systematic observation of seven independent MRI parameters (FI, PS, tear size ML, TS, OG, AHD, IGHD) can help the surgeon to predict the impossibility to obtain complete repair of RCT and to consider different surgical approach. (www.actabiomedica.it)

Management of total hip replacement luxation with triple pelvic osteotomy.

To report the outcome of dogs treated with triple pelvic osteotomy (TPO) for dorsal luxation after total hip replacement (THR). Retrospective clinical case series. Seventeen client-owned animals. Medical records were searched at a single institution for dogs that had been treated with TPO for dorsal THR luxation. The angle of lateral opening (ALO), version angle (VA), and inclination angle (IA) were measured from radiographs after THR and TPO and corrected for pelvic rotation. A paired t test was performed to compare cup orientation after THR and TPO. Functional outcome was assessed at follow-up examination and during telephone interviews. Eighteen TPOs were performed in 17 dogs, and radiographs were available for 15 cases. Open and/or closed hip reduction with additional stabilization was attempted unsuccessfully in 6 dogs prior to TPO. Triple pelvic osteotomy reduced the ALO by a mean of 23.0 ° ± 10.9 ° (P ≤ .001), increased VA by 9.0 ° ± 4.9 ° (P < .001), and increased IA by 2.9 ° ± 5.8 ° (P = .126). An excellent or good outcome was achieved in 12 dogs. Ventral luxation occurred in 3 dogs, and dorsal luxation occurred in 1 dog after TPO. Triple pelvic osteotomy excessively reduced ALO in 2 dogs with ventral luxation. Triple pelvic osteotomy with cup retention is a viable alternative to cup revision for treatment of dorsal luxation of cemented and cementless THR. Triple pelvic osteotomy significantly reduces ALO and increases VA. Careful patient selection is recommended because excessive ventroversion can lead to ventral luxation. Triple pelvic osteotomy offers a revision option that preserves the implant-bone interface and significantly reduces ALO. This technique may be appropriate in dogs with high ALO, luxoid hips, and prior failed revision attempts.

A three-dimensional virtual morphometry study of the sigmoid notch of the distal radius.

Our primary objectives were to create a reliable, noninvasive method for three-dimensional morphometry of deep bony parameters within the sigmoid notch of the distal radius, to identify its morphological patterns, and to identify any significant variation between the left and the right wrists. Our secondary objectives were to obtain morphometric values that could represent our population and to identify any possible ethnic variations. Computed tomography scans of 102 wrists from 51 healthy individuals were analyzed using a virtualization software. Four anatomical parameters at the distal radius sigmoid notch, namely, the radius of curvature, depth, version angle, and sagittal slope were measured. Morphological patterns of the sigmoid notch surface were identified. The results were statistically analyzed to assess the reliability of the technique and were compared with previously published literature. Comparing our findings with previously published values, our study revealed a slightly larger radius of curvature and sagittal slope, while revealing a smaller depth and version. We identified the S-type, C-type, and ski-slope morphological variants. The flat-face morphological variant, however, was not identified. The sigmoid notch at the left and right wrists were similar, except for the radius of curvature. This study demonstrates a noninvasive, fast, reliable, and reproducible technique for analyzing the sigmoid notch of the distal radius. In wrist injuries with intact distal radius sigmoid notch but involving comminuted fractures of the ulnar head, ulnar head replacement may be indicated. In such cases, analysis of the ipsilateral intact sigmoid notch would allow us to prepare an ulnar head prosthesis of appropriate size.

Transvaginal and transperineal ultrasound follow-up after laparoscopic correction of uterine retrodisplacement in women with posterior deep infiltrating endometriosis.

Retrodisplacement of the uterus (retroflexion and/or retroversion) may be associated with pelvic pain symptoms and posterior deep infiltrating endometriosis (DIE). Previous studies in symptomatic women with retrodisplacement of the uterus showed the efficacy of hysteropexy in terms of pain symptoms improvement. To evaluate sonographic, clinical and surgical outcomes of a hysteropexy technique MATERIALS AND METHODS: Laparoscopic round ligament plication and tilting of the uterine fundus in women with uterine retrodisplacement and posterior deep infiltrating endometriosis was performed. Forty-two symptomatic women were enrolled and the sonographic data of each (angle of uterine version and uterine flexion, uterine mobility) was assessed before and after surgery with transvaginal and transperineal approaches. Women were also evaluated at 1, 6 and 12months after surgery for pain symptoms with a numerical rating scale (dysmenorrhoea, dyspareunia and chronic pelvic pain), intraoperative data and surgical complications. The additional mean operative time of hysteropexy procedure was 8±3min. At early follow-up both the uterine angles were significantly (P<0.001) reduced. At 12-month follow-up, seven patients (16.7%) presented a retroverted uterus, while 12 (28.6%) presented a retroflexed uterus; the sliding sign remained negative in four patients (9.5%). A significant improvement of symptoms (P<0.001) was observed during the follow-up. Laparoscopic hysteropexy appears as an effective additional surgical procedure, which can temporarily correct the uterine position in order to reduce the risk of postoperative adhesions.

Modified Friedman technique: a new proposed method of measuring glenoid version in the setting of glenohumeral dysplasia.

Glenoid version angles are measured to objectively follow changes related to glenohumeral dysplasia in the setting of brachial plexus birth palsy. Measuring glenoid version on cross-sectional imaging was initially described by Friedman et al. in 1992. Recent literature for non-dysplastic shoulders advocates time-consuming reconstructions and reformations for an accurate assessment of glenoid version. To compare Friedman's original method for measuring glenoid version to a novel technique we developed ("modified Friedman") with the reference standard of true axial reformations. With institutional review board approval, we retrospectively examined 30 normal and dysplastic shoulders obtained from magnetic resonance imaging examinations of 30 patients with an established diagnosis of brachial plexus birth palsy between January 2012 and September 2017. Four pediatric radiologists performed glenoid version measurements using Friedman's method, the modified Friedman method and a previously described true axial reformation method. The modified Friedman technique better accounts for scapular positioning by selecting a reference point related to the acromion-scapular body interface. Inter-rater reliability and inter-method agreement were assessed using intraclass correlation, paired t-tests and mixed linear model analysis. Equivalence tests between methods were performed per reader. Glenoid version measurements were significantly different when comparing Friedman's method to true axial reformations in normal (-10.8±5.7° [mean±standard deviation] vs. -8.8±5.3°; P≤0.001) and dysplastic shoulders (-34.6±17.7° vs. -28.1±17.5°; P≤0.001). Glenoid version measurements were not significantly different when comparing the modified Friedman's method to true axial reformations in normal (-6.3±5.8° vs. -8.8±5.3°; P=0.06) and dysplastic shoulders (-29.0±18.3° vs. -28.1±17.5°; P=0.06). Friedman's method was not equivalent to true axial reformations for measurements in dysplastic shoulders for all readers (P=0.68, 0.81, 0.86, 0.99); the modified Friedman method was equivalent to of true axial reformations for measurements in dysplastic shoulders for 3 of 4 readers (P≤0.001, P≤0.001, P≤0.001, P=0.10). In glenohumeral dysplasia, the modified Friedman method and post-processed true axial reformations provide statistically similar and reproducible values. We propose that our modified Friedman technique can be performed in lieu of post-processed true axial reformations to generate glenoid version measurements.

Binocular system with asymmetric eyes.

I elaborate binocular geometry with a novel eye model that incorporates the fovea's temporalward displacement and the cornea and the lens' misalignment. The formulated binocular correspondence results in longitudinal horopters that are conic sections resembling empirical horopters. When the eye model's asymmetry parameters' range is that which is observed in healthy eyes, abathic distance also falls within its experimentally observed range. This range in abathic distance is similar to that of the vergence resting position distance. Further, the conic's orientation is specified by the eyes' version angle, integrating binocular geometry with eye movement. This integration presents the possibility for modeling 3D perceptual stability during physiological eye movements.

Periprosthetic acetabular radiolucency progression in mid-term follow-up of the articular surface replacement hip system.

Recent registry studies show that aseptic loosening secondary to osteolysis is the second leading cause of hip implant failure in patients implanted with metal-on-metal (MoM) bearings. The primary aim of our study was to report on the progression of acetabular osteolysis during mid-term follow-up in patients treated with MoM hip resurfacing arthroplasty (HRA) and MoM total hip arthroplasty (THA). The secondary aim was to identify independent predictors of osteolytic lesion progression. A total of 805 patients (805 hips) were included in this study (541 MoM HRA, 264 MoM THA) from a prospective, international clinical registry of the Articular Surface Replacement Hip System. Patients were enrolled a median of 6.6years from surgery. Osteolytic lesion progression was defined either as any lesion developing de novo, or as an existing lesion progressing from radiolucency to osteolysis during the study period (range 0.5-4.3years). The number of cases with any osteolysis or radiolucency was 21 (3.9%) for ASR HRA and 29 (11.0%) for ASR XL THA at enrollment and increased to 69 (12.8%) for ASR HRA and 41 (15.5%) for ASR XL THA after follow-up. Osteolytic lesion progression was found in 66 (12.2%) ASR HRA patients and 31 (11.7%) ASR XL THA patients. Multivariate models determined that lower acetabular version angle (OR 0.963, p = 0.011) and elevated whole blood chromium (OR 1.110, p = 0.044) were independent predictors of osteolytic lesion progression in ASR HRA. We suggest that physicians of patients implanted with ASR HRA implants closely monitor patients with higher chromium levels and lower version angles, as they are at increased risk for osteolytic lesion progression, and we recommend annual radiographic follow-up on all patients with ASR implants.

Accuracy of plain antero-posterior radiographic-based methods for measurement of acetabular cup version.

Acetabular cup version is crucial for successful total hip arthroplasty (THA). Many methods have been described for measurement of cup version angle. The aim of this study is to assess the accuracy of five commonly used methods for measurement of acetabular cup version in plain antero-posterior views of the pelvis and hip. Sixty primary THA cases were subjected postoperatively to plain A-P of the pelvis (AP-P), A-P view of the hip (AP-H), and computed tomography (CT) imaging. The acetabular cup version was measured in AP-P and AP-H by five methods (Lewinnek, Widmer, Hassan et al., Ackland et al., and Liaw et al.). These measurements were compared to the CT measurement. All plain X-ray methods showed no significant differences from the CT, except those of Hassan et al. in AP-H, and Widmer and Ackland et al. in AP-P. For measurement of acetabular cup version angle, we recommend the use of Lewinnek and Liaw et al. methods both in AP-P and in AP-H, while Hassan et al.'s method is recommended in AP-P only, and Widmer and Ackland et al.'s methods in AP-H only.

Impingement-type bony morphology was related to cartilage defects, but not pain in professional ballet dancers’ hips

ObjectivesProfessional ballet dancers may have hip bony morphology that predisposes them to cartilage or labral injury. However, the relationship between bony morphology and pathology has not been investigated in ballet. This study investigates associations between bony morphology, chondrolabral defects and hip pain in ballet dancers. DesignCross-sectional study. Methods33 male and female professional ballet dancers, (mean age 27 years (range 19–39)), completed questionnaires with hip pain measured on a visual analogue scale; and underwent 3.0-T magnetic resonance imaging (3T MRI) to measure lateral centre edge angles (LCEA), alpha angles in the anterior and superior position, femoral neck-shaft angles (NSA) and acetabular version angles; and to detect acetabular labral tear and articular cartilage defects. ResultsSeventeen dancers (51.5%) had impingement-type (alpha angle>50.5° or acetabular version <10° or >20°) and 19 (58%) had instability-type (LCEA<25° or NSA>135°) bony morphology. Cartilage defect prevalence was higher in dancers with impingement-type bony morphology (n=14) compared to those without impingement-type morphology (n=4, p=0.001). There was no relationship between instability-type bony morphology and cartilage defects (p>0.05). There was no relationship between labral tears and bony morphology (p>0.05). Neither chondrolabral pathology nor any morphological feature were associated with hip pain (p>0.05 for all). ConclusionsImpingement-type bony morphology was related to cartilage defects, but not labral tear. Hip pain was not associated with pathology or bony morphology. Longitudinal studies are warranted to determine if bony features, such as cam morphology, acetabular retroversion or anteversion, are precursors to symptomatic hip joint injury or osteoarthritis.

Influence of geometry on proximal femoral shaft strains: Implications for atypical femoral fracture.

Atypical femoral fractures (AFF) are characterized as low-energy fractures of the femoral shaft or subtrochanteric region. Femoral geometry is known to play a role in AFF risk; it is hypothesized that high-risk geometries are associated with elevated femoral shaft strain. However, it is not well known which geometric parameters have the greatest effect on strain, or whether interaction between parameters is significant. The purpose of this study was to thoroughly quantify the relationship between femoral geometry and diaphyseal strain, using patient specific finite element (FE) modelling in concert with parametric mesh morphing. Ten FE models were generated from computed tomography (CT) images of cadaveric femora. Heterogeneous material properties were assigned based on average CT intensities at element locations and models were subject to loads and boundary conditions representing the stance phase of gait. Mesh morphing was used to manipulate 8 geometric parameters: neck shaft angle (NSA), neck version angle (NV), neck length (NL), femoral length (FL), lateral bowing angle (L.Bow), anterior bowing angle (A.Bow), shaft diameter (S.Dia), and cortical bone thickness (C·Th). A 2-Level full factorial analysis was used to explore the effect of different combinations of physiologically realistic minimum and maximum values for each parameter. Statistical analysis (Generalized Estimating Equations) was used to assess main effects and first order interactions of each parameter. Six independent parameters and seven interaction terms had statistically significant (p<0.05) effects on peak strain and strained volume. For both measures, the greatest changes were caused by S.Dia, L.Bow, and A.Bow, and/or first order interactions involving two of these variables. As hypothesized, a large number of geometric measures (six) and first order interactions (seven) are associated with changes in femoral shaft strain. These measures can be evaluated radiographically, which may have important implications for future studies investigating AFF risk in clinical populations.