The fulcrum axis: a new method for determining glenoid version

Experimental guide wire placement for total shoulder arthroplasty in glenoid models: higher precision for patient-specific aiming guides compared to standard technique without learning curve

BACKGROUND

Patient-specific aiming devices (PSAD) may improve precision and accuracy of glenoid component positioning in total shoulder arthroplasty, especially in degenerative glenoids. The aim of this study was to compare precision and accuracy of guide wire positioning into different glenoid models using a PSAD versus a standard guide.

METHODS

Three experienced shoulder surgeons inserted 2.5 mm K-wires into polyurethane cast glenoid models of type Walch A, B and C (in total 180 models). Every surgeon placed guide wires into 10 glenoids of each type with a standard guide by DePuy Synthes in group (I) and with a PSAD in group (II). Deviation from planned version, inclination and entry point was measured, as well as investigation of a possible learning curve.

RESULTS

Maximal deviation in version in B- and C-glenoids in (I) was 20.3° versus 4.8° in (II) (p < 0.001) and in inclination was 20.0° in (I) versus 3.7° in (II) (p < 0.001). For B-glenoid, more than 50% of the guide wires in (I) had a version deviation between 11.9° and 20.3° compared to ≤ 2.2° in (II) (p < 0.001). 50% of B- and C-glenoids in (I) showed a median inclination deviation of 4.6° (0.0°-20.0°; p < 0.001) versus 1.8° (0.0°-4.0°; p < 0.001) in (II). Deviation from the entry point was always less than 5.0 mm when using PSAD compared to a maximum of 7.7 mm with the standard guide and was most pronounced in type C (p < 0.001).

CONCLUSION

PSAD enhance precision and accuracy of guide wire placement particularly for deformed B and C type glenoids compared to a standard guide in vitro. There was no learning curve for PSAD. However, findings of this study cannot be directly translated to the clinical reality and require further corroboration.

Changes in glenohumeral translation, electromyographic activity, and pressure-pain thresholds following sustained or oscillatory mobilizations in stiff and healthy shoulders: Results of a randomized, controlled laboratory trial

STUDY DESIGN

Randomized Controlled Laboratory Study.

BACKGROUND

Posterior glide glenohumeral (GH) mobilizations are utilized to improve motion and decrease pain in patients with shoulder pathologies, thought to be due to capsular stretch and neurophysiologic effects. However, it remains unclear how different GH mobilizations influence mobility, rotator cuff (RC) activity, and pain processing, or if effects are different in stiff (≥15-degree loss of passive motion in any plane) rather than healthy shoulders.

OBJECTIVES

To compare the effects of oscillatory and sustained posterior GH mobilizations on translation, RC activity, and pressure pain threshold (PPT) in stiff and healthy shoulders.

METHODS

Eighty-eight participants, (44 control, 44 stiff shoulders) were randomly assigned to one of two mobilization conditions. Pre-post intervention measurements of PPT, GH translation via ultrasound imaging, and RC activity assessed via electromyography were performed. Sustained or oscillatory grade III posterior GH mobilizations were then provided to all participants. Data were analyzed using tests of difference and regression modeling.

RESULTS

Sustained glides (2.8 ± 3.3 mm) demonstrated significantly greater changes in translation compared to oscillatory glides (1.1 ± 3.9 mm), p = .028. Stiff shoulders demonstrated higher total RC activity than controls both pre (+24.51%, p = .004) and post-intervention (+23.10%, p = .01). Small changes in PPT occurred across all conditions, none reaching clinically meaningful levels.

CONCLUSION

Sustained mobilizations resulted in greater changes in GH translation. RC activity was higher in the stiff shoulder group, and remained higher post-intervention despite gains in GH translation, suggesting a mechanical rather than neurophysiologic effect. There was no meaningful difference in PPT between modes of mobilization.

LEVEL OF EVIDENCE

Therapy, Randomized Controlled Laboratory Study, Level 1b.

The fulcrum axis: an accurate measure of glenoid version on radiographs and computed tomography

BACKGROUND

Proper glenoid position in total shoulder arthroplasty (TSA) is important. However, traditional glenoid version (GV) measurements overestimate retroversion on radiographs (XR) and computed tomography (CT).The fulcrum axis (FA) uses palpable surface landmarks and may be useful as an intra-operative guide. Also, the FA has not yet been validated on XR or CT in an arthritic population.

METHODS

Four observers measured FA and GV on the XR, CT and three-dimensional CT (3DCT) of 40 patients who underwent TSA at a single institution from 2009 to 2015. Reliability and accuracy of FA and GV were calculated for XR and CT, using 3DCT as the gold standard.

RESULTS

The mean FA and GV were 7.768° and 18.910° on XR; 6.23° and 12.920° on CT; and 8.100° and 7.740° on 3DCT, respectively. FA and GV were significantly different for XR and CT (p < 0.001) but not for 3DCT (p = 0.725). The inter-rater reliability, intra-rater reliability and accuracy of FA were not significantly different from GV and were 0.929 to 0.948, 0.779 to 0.974 and 0.674 to 0.705, respectively. However, the absolute difference of FA was closer to the gold standard (3DCT) than GV for XR (0.330° versus 11.172°) and CT (1.871° versus 5.178°) (p < 0.001).

CONCLUSIONS

FA showed comparable reliability and accuracy to GV. However, FA more accurately reflected the gold standard.

Morphologic variations of the scapula in 3-dimensions: a statistical shape model approach

BACKGROUND

Morphologic variations of the scapula and acromion have been found to be associated with shoulder pathology. This study used statistical shape modelling to quantify these variations in healthy shoulders.

MATERIALS AND METHODS

A statistical shape model of the scapula was created using 3-dimensional computed tomography reconstructions of 108 survey-confirmed nonpathologic shoulders of 54 patients. The mean shape and the 95% confidence interval were calculated and analyzed in the first 5 shape modes.

RESULTS

The first 5 shape modes consisted of consecutively sized (72% of total variation), rotation of the coracoacromial complex (5%), acromial shape and slope (4%), shape of the scapular spine (2%), and acromial overhang (2%).

DISCUSSION AND CONCLUSION

In healthy shoulders, a certain variation in rotation of the coracoacromial complex and in acromial shape and slope was observed. These new parameters might be correlated with shoulder pathology such as glenohumeral osteoarthritis or rotator cuff tears.

Relationship of Intraoperative Anatomical Landmarks, the Scapular Plane and the Perpendicular Plane with Glenoid for Central Guide Insertion during Shoulder Arthroplasty

Background

This study was undertaken to evaluate the positional relationship between planes of the glenoid component (the scapular plane and the perpendicular plane to the glenoid) and its surrounding structures.

Methods

Computed tomography (CT) images of both shoulders of 100 patients were evaluated using the 3-dimensional CT reconstruction program (Aquarius^®; TeraRecon). We determined the most lateral scapular bony structure of the scapular plane and measured the shortest distance between the anterolateral corner of the acromion and the scapular plane. The distance between the scapular plane and the midpoint of the line connecting the posterolateral corner of acromion and the anterior tip of the coracoid process (fulcrum axis) was also evaluated. The perpendicular plane was then adjusted to the glenoid and the same values were re-assessed.

Results

The acromion was the most lateral scapular structure of scapular plane and perpendicular plane to the glenoid. The average distance from the anterolateral corner of the acromion to the scapular plane was 10.44 ± 5.11 mm, and to the plane perpendicular to the glenoid was 9.55 ± 5.13 mm. The midpoint of fulcrum axis was positioned towards the acromion and was measured at 3.90 ± 3.21 mm from the scapular plane and at 3.84 ± 3.17 mm from the perpendicular plane to the glenoid.

Conclusions

Our data indicates that the relationship between the perpendicular plane to the glenoid plane and its surrounding structures is reliable and can be used as guidelines during glenoid component insertion (level of evidence: Level IV, case series, treatment study).

Glenoid component loosening associated with increased critical shoulder angle at midterm follow-up

BACKGROUND

Glenoid component loosening is a common failure mode of total shoulder arthroplasty (TSA). A larger critical shoulder angle (CSA) may cause superior glenoid component loading and more rapid component loosening. The purpose of this study was to define the relationship between the CSA and glenoid component loosening in midterm follow-up after TSA.

METHODS

We conducted a retrospective study of 61 primary TSAs for osteoarthritis with an average follow-up of 5.0 ± 2.2 years without surgical revision. Standard true anteroposterior radiographs postoperatively and at longest follow-up were graded in a blinded and repetitive nature for pegged glenoid radiolucent lines and measured for the CSA. An "at-risk" glenoid was defined as grade 3 or higher lucency.

RESULTS

The average CSA was 32° ± 5°, median midterm lucency grade was 2 (range, 0-5), and median progression of lucency grade was 1 (range, -1 to 4). At midterm follow-up, 20% of TSAs were grade 3 or higher mean glenoid lucency, with an average CSA of 36°. There was a statistically significant correlation between CSA and both glenoid lucency grade (odds ratio, 1.20 per degree CSA) and progression of lucency grade (odds ratio, 1.24). An increase in CSA of 10° was associated with a 6.2-fold increased odds of having an at-risk glenoid.

CONCLUSION

This study identifies the CSA as a risk factor for glenoid component loosening after TSA. Our findings suggest that the CSA may be a modifiable factor during surgery to improve glenoid component outcomes.

Posterior open wedge osteotomy of the scapula neck for the treatment of advanced shoulder osteoarthritis with posterior head migration in young patients

BACKGROUND

Treatment of young, active patients with symptomatic glenohumeral osteoarthritis, excessive glenoid retroversion, and static posterior humeral subluxation is challenging. Correction of glenoid retroversion may lead to centric loading and perhaps recenter the humeral head. We describe the functional and radiologic outcomes after corrective osteotomy of the glenoid in this population of patients.

MATERIALS AND METHODS

In this retrospective study, we included 10 shoulders (8 patients) that were observed for a mean of 33.4 months (range, 24-52 months) after corrective osteotomy of the glenoid. The mean age at surgery was 41.5 years (range, 24-51 years). On standardized axial images, glenoid retroversion and posterior static humeral subluxation were measured preoperatively and postoperatively and at the final follow-up. At final follow-up, anterior and posterior axial radiographs were performed to determine humeral head position in different arm positions. Clinical follow-up included Constant-Murley score, subjective shoulder value, and patient satisfaction.

RESULTS

The mean Constant-Murley score improved significantly from 45.1 points (range, 24-71) to 64.1 points (range, 44-92; P < .001). The average degree of anterior flexion improved significantly from 117° (range, 50°-160°) to 143° (range, 110°-180°; P = .006). The mean glenoid retroversion changed from 16° (range, 11°-31°) preoperatively to 5° (range, 13° anteversion-16° retroversion; P = .003) at the final follow-up. The mean posterior static subluxation of the humeral head changed from 5 mm (range, 0-10 mm) preoperatively to 6 mm (range, 0-14 mm; P = .259) at the final follow-up.

CONCLUSIONS

This study shows that posterior open wedge osteotomy of the glenoid neck provides excellent correction of glenoid retroversion.

The morphometric anatomy of the delto-fulcral triangle: A 3D CT-based reconstruction study

This study introduced the new delto-fulcral triangle (DFT), the first anatomical model of its kind. As seen from the orthopaedician's supraspinatus-outlet view, the antero-superior point of the coracoid process along with the lateral- and posterior-most acromial landmarks form the boundaries of the DFT. Since these osseous scapular landmarks accounted for both dynamic and static stabilisers of the glenohumeral joint, knowledge of the anatomical features of the DFT may prove beneficial to the orthopaedic surgeon. This study thus aimed to investigate the morphometry of the new DFT. The bony surfaces of one-hundred and sixty-nine (n = 169) normal and pathological (Omarthrosis and Cuff-Tear Arthropathy) shoulders from the hospital's CT scan database were reconstructed (Mimics^®: Materialise, Leuven, Belgium). Statistical significance was observed between all three groups for Side 2 (LACPF: distance between most lateral and most posterior points of the acromion) and angles α (angle between sides 1 and 3) and β (angle between sides 1 and 2) of the DFT. It was postulated that although pathological cases present with a smaller lateral acromial distance (LACPF), their lateral acromion landmark is more posteriorly placed from the scapular plane than that of a normal case. As the aspects of the morphometric anatomy of the DFT presented with levels of statistical significance, it may provide a means to evaluate the anatomy of normal and pathological cases. Additionally, the three osseous scapular landmarks that create the DFT are clearly visualised and palpable, therefore they are easily reproducible from both X-ray images and CT scans.

Computerized 3D morphological analysis of glenoid orientation

An accurate preoperative measurement of glenoid orientation is crucial for evaluating pathologies and successful total shoulder arthroplasty. Existing methods may be labor-intensive, observer-dependent, and sensitive to the misalignment between the scapula plane and CT scanning direction. In this study, we proposed a computation framework and performed an automated analysis of the glenoid orientation based on 3D surface data. Three-dimensional models of 12 scapulae were analyzed. The glenoid cavity and external anatomical features were automatically extracted from these 3D models. Glenoid version was calculated using the scapula plane and the fulcrum axis alternatively. Glenoid inclination was measured both relative to transverse axis of the scapula and the medial pole-inferior tip axis. The mean (±SD) of the fulcrum-based glenoid version was -0.55° (±4.17°), while the scapular-plane-based glenoid version was -5.05° (±3.50°). The mean (±SD) of glenoid inclinations based on the medial pole and inferior tip was 12.75° (±5.03°) while the mean (±SD) of the glenoid inclination based on the medial pole and glenoid center was 4.63° (±4.86°). Our computational framework was able to extract the reproducible morphological measures free of inter- and intra- observer variability. For the first time in 3D, we showed that the fulcrum axis was practically perpendicular to the glenoid plane normal (radial line), and thus extended the fulcrum-based glenoid version for quantifying 3D glenoid orientation.

Application of the fulcrum axis to estimate the central scapular axis

BACKGROUND

Glenoid resurfacing can be a challenging component of total shoulder arthroplasty when significant glenoid retroversion or deformity is present. The purpose of this study was to determine whether a newly designed glenoid-targeting guide using the parallel relationship between glenoid version and an anatomic fulcrum axis could accurately estimate the central axis of the scapula.

MATERIALS AND METHODS

Three orthopaedic surgeons used a newly designed glenoid-targeting guide to place a guide pin into 6 normal Sawbones scapulae (Pacific Research Laboratories, Vashon Island, WA, USA), 6 retroverted Sawbones scapulae, 8 cadaveric scapular specimens, and 5 cadaveric shoulder specimens. Angles of deviation from the central scapular axis and from perpendicular to the fulcrum axis were measured.

RESULTS

The mean pin deviation angle from the central scapular axis and the mean fulcrum deviation angle for the normal Sawbones scapulae were 1.7° (SD, 1.2°) and 2.1° (SD, 1.5°), respectively. For altered retroverted Sawbones scapulae, the mean deviation angles were 1.8° (SD, 1.2°) and 2.8° (SD, 1.6°), respectively. The combined mean pin deviation angle and mean fulcrum deviation angle for cadaveric shoulder specimens were 2.8° (SD, 3.3°) and 2.3° (SD, 2.3°), respectively. The surgeons' results did not differ significantly whether using Sawbones models, cadaveric scapular specimens, or cadaveric shoulder specimens.

CONCLUSION

A glenoid-targeting guide based on the relationship of the fulcrum axis and glenoid version can be used to accurately estimate the central scapular axis. Such a tool can be accurate and reliable intraoperatively, aiding in glenoid component placement to within 5° of ideal version, irrespective of glenoid deformity.

[Indication for primary fracture prosthesis of the shoulder]

Although fractures of the proximal humerus are one of the most common osteoporotic fracture types, no generally accepted treatment algorithm exists in the current literature. For young patients with high functional demands and good rehabilitation potential, we recommend humeral head salvage therapy. If symptomatic humeral head necrosis occurs, the implantation of an anatomic endoprothesis is possible on a secondary basis. For patients with a biological age > 70 years suffering from a persisting defect of the rotator cuff along with a humeral head fracture or from a multiple fragment fracture of the humeral head, we increasingly prefer implantation of a reverse shoulder prosthesis due to good clinical results. However, because of technical aspects and a high complication rate, treatment using the reverse fracture prosthesis should be reserved for surgeons with expertise in this particular field. After analyzing the fracture- and patient-specific risk factors and performance expectations, the trauma surgeon can select the best individual therapy with the patient.

A comparison of glenoid morphology and glenohumeral range of motion between professional baseball pitchers with and without a history of SLAP repair

PURPOSE

We sought to examine the relation among glenoid morphology, glenohumeral range of motion (ROM), and history of shoulder injury in professional baseball pitchers.

METHODS

We studied 58 professional baseball pitchers. Internal rotation (IR) and external rotation (ER) ROM was measured at 90° of abduction. Horizontal adduction (HAdd) ROM was also measured. Glenoid superior inclination and glenoid retroversion (GRV) were then measured radiographically. Separate mixed-model analyses of variance were used to compare dependent measures between the dominant and nondominant shoulders of pitchers with or without a history of SLAP repair. Significant interaction effects were interpreted by use of a test for simple main effects (α = .05).

RESULTS

GRV was significantly greater on the dominant side (8.7° ± 5.6°) versus nondominant side (5.5° ± 5.2°) (P = .001), whereas glenoid superior inclination was equivalent (99.5° ± 4.3° for dominant side v 99.2° ± 4.4° for nondominant side, P = .853). Post hoc analysis indicated that pitchers with a history of SLAP repair did not display an adaptive increase in dominant GRV compared with nondominant GRV (P = .016). There were no statistical differences between groups for ER (P = .29), IR (P = .39), or HAdd (P = .39). The dominant shoulder displayed greater ER (mean increase, 6.2° ± 12.2°) with a complementary decrease in IR (mean decrease, 5.8° ± 13.2°) and HAdd (mean decrease, 8.9° ± 13.7°) compared with the nondominant side.

CONCLUSIONS

Our findings suggest that the development of increased GRV in the dominant shoulder of professional baseball pitchers may be a protective adaptive change not reflected in glenohumeral ROM measures.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Bony adaptation of the proximal humerus and glenoid correlate within the throwing shoulder of professional baseball pitchers

BACKGROUND

Elite throwing athletes have increased proximal humeral retrotorsion (HRT) and glenoid retroversion (GRV) in their throwing shoulders compared with their nonthrowing shoulders. These adaptive morphologic changes are thought to be independently protective against shoulder injury; however, their relationship to each other is poorly understood.

PURPOSE

To determine if an association exists between HRT and GRV within the same shoulders of professional pitchers.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

The HRT and GRV measurements were determined using published techniques in asymptomatic bilateral shoulders of 32 professional pitchers (mean age, 23 years). Three measurements for each variable were averaged, and the reliability of the techniques was verified. The relationship between HRT and GRV within the same shoulders was determined with Pearson correlation coefficients. Paired t tests were used to compare HRT and GRV between the throwing and nonthrowing shoulder. Simple ratios were calculated between HRT and GRV.

RESULTS

Humeral retrotorsion and GRV were both significantly greater on the throwing side compared with the nonthrowing side (HRT: throwing = 9.0° ± 11.4° and nonthrowing = 22.1° ± 10.7°, P < .001; GRV: throwing = 8.6° ± 6.0° and nonthrowing = 4.9° ± 4.8°, P = .001). Within the same shoulders, there was a statistically significant positive association between HRT and GRV on the throwing side (r = 0.43, P = .016) but not on the nonthrowing side (r = -0.13, P = .50). The HRT:GRV ratio was 2.3:1 for throwing shoulders and 7:1 for nonthrowing shoulders.

CONCLUSION

The concurrent increases in dominant shoulder HRT and GRV were observed as a 2:1 "thrower's ratio." As this relationship was not observed on the nondominant shoulder, it suggests that bony adaptation of the proximal humerus and glenoid are coupled during skeletal development in the throwing shoulder. Longitudinal studies are needed to confirm this hypothesis.

Glenoid spherical orientation and version

HYPOTHESIS

Glenoid orientation likely plays an important role in shoulder mechanics and has been associated with glenohumeral instability, rotator cuff tears, and total shoulder arthroplasty outcome. Glenoid version and inclination measurements are widely used, but these measurements are 2-dimensional, and orientation of the central face must be inferred from 2 points on the outer rim. This study tested the hypothesis that sphere fitting provides an optimal assessment of glenoid face 3-dimensional orientation, and clinically important differences will exist in some individuals between sphere fit orientation and traditional version measurement.

MATERIALS AND METHODS

Computed tomography scans of 20 normal glenoids were obtained. Glenoid version was measured from resliced, pure transverse images at a series of glenoid heights. Separately, the 3-dimensional surface of each glenoid face was reconstructed. A sphere was fit to the glenoid face, and its orientation was described by 2 angles analogous to version and inclination.

RESULTS

"Sphere fit version" averaged -3.2° ± 3.4° (negative indicating retroversion), and "sphere fit inclination" averaged 1.3° ± 4.7°. Absolute differences between sphere fit version and the standard mid-glenoid version averaged 1.5° (maximum 4.0°) across patients. The glenoids were, on average, 5.5° more retroverted at the 80% height than at the 20% height.

DISCUSSION

Three-dimensional aspects of the glenoid, including the spiraling twist evidenced by increased retroversion superiorly, are accounted for in this novel sphere-fitting approach for assessing glenoid orientation.

CONCLUSIONS

For most normal glenoids, midglenoid version appears to provide an adequate measure of glenoid central face orientation. Sphere fitting has potential utility in optimizing glenoid implant alignment in total shoulder arthroplasty.

Glenoid version: how to measure it? Validity of different methods in two-dimensional computed tomography scans

HYPOTHESIS

Recognition of the glenoid version is important for evaluation of different pathologies such as degenerative wear, shoulder instability, or congenital deformity. Surgical strategies can change significantly in the presence of major retroversion. There is no consensus on the method to use to evaluate version. This study compared different measurement strategies in 116 patients with shoulder computed tomography (CT) scans. We hypotheses that the methods will give different value for evolution.

METHODS

Shoulder axial CT images were reviewed, and the image inferior to the base of the coracoid was selected. The glenoid version was measured according to the Friedman method and the scapula body method. Three orthopedic surgeons independently examined the images 2 times, and intraobserver and interobserver reliability was calculated using intraclass correlation (ICC).

RESULTS

Group 1 (n = 53): The average glenoid version was significantly different between the 2 measurement techniques for all 3 observers, with an average of -7.29° for the scapula body method and -10.43° for Friedman method. For group 2 (B2 glenoid group, n = 63): The most reliable method for measurement of B2 glenoid (glenoid with posterior erosion) version was the association of the Friedman line for the scapula axis and the intermediate glenoid line, with excellent intraobserver reliability (ICC > 0.957) and interobserver reliability (ICC = 0.954).

DISCUSSION

The glenoid version measurement is reliable on a 2D CT Scan. According to correlation found in our paper and those of the literature it seems that there is no advantage on 3D CT Scan to assess version in terms of reliability of measures.

CONCLUSION

Combining the Friedman method to determine the scapula axis with an intermediate glenoid line in B2 glenoid yield the most reliable measurements.

Posterosuperior and anterosuperior impingement of the shoulder in overhead athletes-evolving concepts

During throwing motion the athlete puts enormous stress on both the dynamic and the static stabilisers of the shoulder. Repetitive forces cause adaptive soft tissue and bone changes that initially improve performance but ultimately may lead to shoulder pathologies. Although a broad range of theories have been suggested for the pathophysiology of internal impingement, the reasons are obviously multifactorial. This review aims to critically analyse the current literature and to summarise clinically important information. The cardinal lesions of internal impingement, articular-sided rotator cuff tears and posterosuperior labral lesions, have been shown to occur in association with a number of other findings, most importantly glenohumeral internal rotation deficit and SICK scapula syndrome, but also with posterior humeral head lesions, posterior glenoid bony injury and, rarely, with Bankart and inferior glenohumeral ligament lesions. Extensive biomechanical and clinical research is necessary before a complete understanding and reconciliation of the varying theories of the pathomechanisms of injury can be developed.

Use of the fulcrum axis improves the accuracy of true anteroposterior radiographs of the shoulder

In 100 patients the fulcrum axis which is the line connecting the anterior tip of the coracoid and the posterolateral angle of the acromion, was used to position true anteroposterior radiographs of the shoulder. This method was then compared with the conventional radiological technique in a further 100 patients.

Three orthopaedic surgeons counted the number of images without overlap between the humeral head and glenoid and calculated the amount of the glenoid surface visible in each radiograph. The analysis was repeated for intraobserver reliability. The learning curves of both techniques were studied.

The amount of free visible glenoid space was significantly higher using the fulcrum-axis method (64 vs 31) and the comparable glenoid size increased significantly (8.56 vs 6.47). Thus the accuracy of the anteroposterior radiographs of the shoulder is impaired by using this technique. The intra and interobserver reliability showed a high consistency. No learning curve was observed for either technique.