The shape of the inferior part of the glenoid: a cadaveric study

Magnetic resonance imaging evaluation of normal glenoid length and width: an anatomic study

PURPOSE

The purpose of this study was to evaluate the measured dimensions of the normal glenoid on sagittal magnetic resonance (MR) imaging to determine whether a fixed ratio of glenoid length and width can be determined.

METHODS

MR images of 90 glenoids in 84 patients were analyzed. The mean age was 54.8 years, with 44 male and 40 female patients. Glenoid length and width at the widest dimension were measured and recorded by 3 independent examiners. The ratio of length to width and the ratio of the length of the superior pole at the widest point to the total length were calculated. Intraclass correlation coefficients, Spearman and Pearson correlations, regression analysis with cross validation, and coefficients of variation were calculated.

RESULTS

The mean glenoid length was 37.5 ± 3.8 mm, whereas the mean width was 24.4 ± 2.9 mm. The mean ratio of length to width was 1.55 ± 0.1, whereas the mean ratio of the distance from the superior pole to the widest point to the total glenoid length was 0.64 ± 0.03. The calculated ratios were less variable than the absolute length and width. Cross validation of length for width showed a 95% prediction band width of 4.48 mm, with an average absolute error of prediction of 1.46 mm, and was equally specific when separated by gender. The width was equal to 0.65 times the length.

CONCLUSIONS

Measurement of glenoid length and width using MR imaging results in a consistent ratio of length to width independent of patient age and gender, where the width was equal to 0.65 times the length at a point two-thirds along the inferosuperior axis.

LEVEL OF EVIDENCE

Level IV, case series.

Shoulder instability in the setting of bipolar (glenoid and humeral head) bone loss: the glenoid track concept

BACKGROUND

An assortment of variables has been used in predicting anterior shoulder instability resulting from pathologic engagement of Hill-Sachs lesions on the glenoid. The glenoid track is a unique biomechanical model that relates both Hill-Sachs and bony Bankart lesions to predict shoulder engagement. We examined the glenoid track concept to determine if it provides a model that unifies glenoid rim and humeral head bone loss in predicting engagement.

QUESTIONS/PURPOSES

In this review we addressed two questions: (1) How are humeral head and glenoid rim bony defects and their interactions quantified? (2) Why is the concept of the glenoid track important?

METHODS

We performed a systematic review of the literature using PubMed (MEDLINE) and OVID for biomechanical studies and peer-reviewed articles published until March 2013. Twenty-four studies fit the inclusion criteria. These were subdivided into four anatomic studies, four studies quantifying glenohumeral bone loss, nine studies biomechanically defining shoulder engagement, six studies analyzing current treatment models, and one clinical study to be included in the final review.

RESULTS

Data demonstrate pathologic engagement is dependent on the medial margin of the Hill-Sachs lesion traveling outside the glenoid track. The width of the glenoid track decreases accordingly if there is a glenoid defect, making engagement more likely. Most treatment models focus on widening the glenoid track before addressing Hill-Sachs lesions.

CONCLUSIONS

The glenoid track uses both glenoid and humeral head bone loss to predict subsequent risk of humeral head engagement and possible dislocation. The glenoid track shows us that restoring the track to its natural width should be among the surgeon's first priority in restoring shoulder stability. Humeral head lesions, also known as Hill-Sachs lesions, are surgically addressed when they cause clinical symptoms. Symptoms arise when the medial margin of the defect engages the glenoid track.

Arthroscopic distal clavicular autograft for treating shoulder instability with glenoid bone loss

Glenoid bone loss is a significant risk factor for failure after arthroscopic shoulder stabilization. Multiple options are available to reconstruct this bone loss, including coracoid transfer, iliac crest bone graft, and osteoarticular allograft. Each technique has strengths and weaknesses. Coracoid grafts are limited to anterior augmentation and, along with iliac crest, do not provide an osteochondral reconstruction. Osteochondral allografts do provide a cartilage source but are challenged by the potential for graft rejection, infection, cost, and availability. We describe the use of a distal clavicular osteochondral autograft for bony augmentation in cases of glenohumeral instability with significant bone loss. This graft has the advantages of being readily available and cost-effective, it provides an autologous osteochondral transplant with minimal donor-site morbidity, and it can be used in both anterior and posterior bone loss cases. The rationale and technical aspects of arthroscopic performance will be discussed. Clinical studies are warranted to determine the outcomes of the use of the distal clavicle as a graft in shoulder instability.

The quantification of glenoid bone loss in anterior shoulder instability; MR-arthro compared to 3D-CT

OBJECTIVE

The purpose of this study is to investigate if magnetic resonance imaging with intra-articular contrast (MR-arthro) is as reliable as three-dimensionally reconstructed computed tomography imaging (3D-CT) in quantifying the glenoid bone loss in patients with anterior shoulder instability.

MATERIALS AND METHODS

Thirty-five patients were included. Sagittal MR-arthro and 3D-CT images of the glenoid surface were obtained pre-operatively. Two observers measured these images twice with OsiriX software in a randomized and blinded way. The intraclass correlations (ICC) of the intra- and inter-observer reliability within one method and an additional Bland-Altman plot for calculating agreement between the two methods were obtained.

RESULTS

The joint estimates of the intra-observer reliability, taking into account the data from both observer A and B, for 3D-CT and MR-arthro were good to excellent. The intra-observer reliability was 0.938 (95% CI: 0.879, 0.968) for 3D-CT and 0.799 (95% CI: 0.639, 0.837) for MR-arthro. The inter-observer reliability between the two observers within one method (3D-CT or MR-arthro) was moderate to good. 3D-CT: 0.724 (95% CI: 0.236, 0.886) and MR-arthro: 0.534 (95% CI: 0.128, 0.762). Comparing both the 3D-CT and MR-arthro method, a Bland-Altman plot showed satisfying differences with the majority of outcomes (89%) within 1 SD.

CONCLUSIONS

Good to excellent intra- and moderate to good inter-observer correlations and a satisfying Bland-Altman plot when compared to 3D-CT show tendencies that MR-arthro is reliable and valid for measuring bony defects of the glenoid.

Feasibility of an osteochondral allograft for biologic glenoid resurfacing

BACKGROUND

Concerns regarding insufficient press fit and glenoid vault cortical blowout make glenoid osteochondral allografting uncommon. We used 3-dimensional computed tomography modeling to test glenoid osteochondral allografting feasibility.

MATERIALS AND METHODS

Sixteen cadaveric shoulders without osteoarthritis underwent computed tomography scans to create 3-dimensional models. The diameter of circular center-based reaming reaching the medial endosteal surface at depths of 4, 6, and 8 mm and the clock face position of the most shallow points were calculated. Demographic factors associated with graft diameter were analyzed by step-wise multiple regressions.

RESULTS

Shallower graft depths allowed larger graft diameters (P < .001). With a graft depth of 4 mm, 56% of glenoids allowed 20-mm-diameter grafts and 94% accommodated 16-mm grafts versus 31% and 75%, respectively, for a graft depth of 6 mm and 13% and 38%, respectively, for a graft depth of 8 mm. Increasing graft depth decreased graft glenoid coverage: mean coverage was 51.9% ± 12.2%, 36.3% ± 12.9%, and 23.8% ± 14.2% for 4-, 6-, and 8-mm depths, respectively. The glenoid's most shallow point was between the 1:30 clock face position and 3-o'clock position in reference to a right shoulder in 69%, 75%, and 44% of glenoids for 4-, 6-, and 8-mm depths, respectively. Although female gender, patient height, and glenoid height and width were associated with graft diameter, multiple regression analysis showed that patient height was the only independent variable associated with accommodated graft diameter at depths of 4, 6, and 8 mm (P = .001, P = .001, and P = .003, respectively).

CONCLUSION

Most glenoids support center-based grafts of 16 to 20 mm in diameter at a depth of 4 mm, covering an average of 51.9% of the glenoid. Accommodated graft size decreases as reaming depth increases.

Validity of arthroscopic measurement of glenoid bone loss using the bare spot

PURPOSE

Our aim was to test the validity of using the bare spot method to quantify glenoid bone loss arthroscopically in patients with shoulder instability.

METHODS

Twenty-seven patients with no evidence of instability (18 males, nine females; mean age 59.1 years) were evaluated arthroscopically to assess whether the bare spot is consistently located at the center of the inferior glenoid. Another 40 patients with glenohumeral anterior instability who underwent shoulder arthroscopy (30 males, ten females; mean age 25.9 years) were evaluated for glenoid bone loss with preoperative three-dimensional computed tomography (3D-CT) and arthroscopic examination. In patients without instability, the distances from the bare spot of the inferior glenoid to the anterior (Da) and posterior (Dp) glenoid rim were measured arthroscopically. In patients with instability, we compared the percentage glenoid bone loss calculated using CT versus arthroscopic measurements.

RESULTS

Among patients without instability, the bare spot could not be identified in three of 27 patients. Da (9.5±1.2 mm) was smaller than Dp (10.1±1.5 mm), but it was not significantly different. However, only 55% of glenoids showed less than 1 mm of difference between Da and Dp, and 18% showed more than 2 mm difference in length. The bare spot could not be identified in five of 40 patients with instability. Pearson's correlation coefficient showed significant (P<0.001) and strong (R (2)=0.63) correlation in percentage glenoid bone loss between the 3D-CT and arthroscopy method measurements. However, in ten shoulders (29%), the difference in percentage glenoid bone loss between 3D-CT and arthroscopic measurements was greater than 5%.

CONCLUSION

The bare spot was not consistently located at the center of the inferior glenoid, and the arthroscopic measurement of glenoid bone loss using the bare spot as a landmark was inaccurate in some patients with anterior glenohumeral instability.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Use of 3D MR reconstructions in the evaluation of glenoid bone loss: a clinical study

OBJECTIVE

To assess the ability of 3D MR shoulder reconstructions to accurately quantify glenoid bone loss in the clinical setting using findings at the time of arthroscopy as the gold standard.

MATERIALS AND METHODS

Retrospective review of patients with MR shoulder studies that included 3D MR reconstructions (3D MR) produced using an axial Dixon 3D-T1W-FLASH sequence at our institution was conducted with the following inclusion criteria: history of anterior shoulder dislocation, arthroscopy (OR) performed within 6 months of the MRI, and an estimate of glenoid bone loss made in the OR using the bare-spot method. Two musculoskeletal radiologists produced estimates of bone loss along the glenoid width, measured in mm and %, on 3D MR using the best-fit circle method, which were then compared to the OR measurements.

RESULTS

There were a total of 15 patients (13 men, two women; mean age, 28, range, 19-51 years). There was no significant difference, on average, between the MRI (mean 3.4 mm/12.6 %; range, 0-30 %) and OR (mean, 12.7 %; range, 0-30 %) measurements of glenoid bone loss (p = 0.767). A 95 % confidence interval for the mean absolute error extended from 0.45-2.21 %, implying that, when averaged over all patients, the true mean absolute error of the MRI measurements relative to the OR measurements is expected to be less than 2.21 %. Inter-reader agreement between the two readers had an IC of 0.92 and CC of 0.90 in terms of percentage of bone loss.

CONCLUSIONS

3D MR reconstructions of the shoulder can be used to accurately measure glenoid bone loss.

Shoulder instability with concomitant bone loss in the athlete

Thorough evaluation of the athlete with persistent shoulder instability and appropriate use of imaging modalities, such as 3-dimensional computed tomography, can help quantify the severity of bony deficiency. Based on obtained imaging and examination, surgical and nonsurgical methods can be considered. In many situations both the humeral- and glenoid-sided bone loss must be addressed. Depending on the extent of bone loss, athletic demands, and surgeon experience, arthroscopic or open surgical options can provide shoulder stability and return athletes to their prior level of activity.

The medial-ridge sign as an indicator of anterior glenoid bone loss

BACKGROUND

The goal of this study was to investigate the incidence of a medial bony ridge at the scapular neck in patients with recurrent anterior shoulder instability and analyze its reliability in identifying anterior glenoid rim bone loss.

METHODS

A total of 109 shoulders in 105 consecutive patients underwent primary surgical stabilization for recurrent anterior shoulder instability with preoperative 2-dimensional and 3-dimensional computed tomography (CT) evaluation. The CT images of each affected shoulder were analyzed for the extent of anterior glenoid bone loss and the presence of a "medial-ridge sign." The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the medial-ridge sign were calculated for different sizes of glenoid rim defects.

RESULTS

A positive medial-ridge sign was detected in 77.1% of the shoulders. The sensitivity of the medial-ridge sign ranged from 81.6% (95% confidence interval [CI], 73.0%-87.9%) for defects greater than 0% to 100% (95% CI, 82.4%-100%) for defects ≥20%. The PPV of the medial-ridge sign decreased from 100% for defects >0% to 11.9% for defects ≥25%. The specificity of the medial-ridge sign decreased from 100% (95% CI, 61.0-100%) for defects >0%, to 25.3% (95% CI, 17.7%-34.6%) for defects ≥25%. The NPV of the medial-ridge sign increased from 24.0% for defects >0% to 100% for defects >20%.

CONCLUSION

The medial-ridge sign represents a CT-based radiologic sign with high sensitivity and NPV for identification of significant anterior glenoid rim defects in case of recurrent anterior shoulder instability.

Glenoid bare area: arthroscopic characterization and its implications on measurement of bone loss

PURPOSE

The purpose of this study was to characterize arthroscopically the frequency and location of the glenoid bare area.

METHODS

Three fellowship-trained orthopaedic sports surgeons evaluated and characterized the bare area of the glenoid in 52 consecutive patients undergoing arthroscopic surgery of the shoulder without a diagnosis of instability. Among the patients with a visible bare area, the position was measured, and when eccentrically located, an apparent bone loss or gain was calculated.

RESULTS

The bare area of the glenoid was observed in only 48% of patients undergoing arthroscopic surgery, and when observed, it was at the center only 37% of the time. Of the glenoids with visible bare areas, 8% were located anteriorly enough to result in an apparent bone loss calculation of greater than 20%. An additional 25% of visible bare areas were posteriorly located, resulting in an apparent bone gain.

CONCLUSIONS

The glenoid bare area is a variably visible and eccentric landmark on the glenoid and thus should not be used as the sole reference point to measure glenoid bone loss.

Reliability and validity assessment of a glenoid bone loss measurement using the Bernageau profile view in chronic anterior shoulder instability

BACKGROUND

One of the identified risk factors for anterior shoulder instability is bone loss on the anterior-inferior glenoid rim. The aim of our study was to assess intraobserver and interobserver reproducibility of the Bernageau view to estimate glenoid bone loss and validate this radiographic method with computed tomography (CT) scan. The second objective was to find correlation between Bernageau and arthroscopic bone loss measurements.

MATERIALS AND METHODS

Twenty patients were included retrospectively. Two independent observers evaluated glenoid bone loss with the ratio between glenoid joint surface diameters of the pathologic and healthy shoulders on Bernageau views. Results were compared with CT (gold standard) and arthroscopic measurements. Validity and reliability of Bernageau measurement were assessed with Spearman correlation coefficients (r) and intraclass correlation coefficients (ρ).

RESULTS

The interobserver and intraobserver reliability and the validity of Bernageau measurement compared with the reference test, the CT scan, were all excellent, with a Spearman ρ between 0.56 (P = .0002) and 0.95 (P < .00001) and an intraclass correlation coefficient between 0.82 (P = .0007) and 0.97 (P < .10(-5)). There was no correlation with arthroscopic evaluation.

CONCLUSION

The glenoid bone defect measurement on the Bernageau profile view is a valid and reliable method. Furthermore, it is easy to use in current clinical practice. Surgeons can therefore consider it as a tool for preoperative planning, and its use could decrease CT scan indications.

Determination of a reference system for the three-dimensional study of the glenohumeral relationship

OBJECTIVE

Knowledge of the normal and pathological three-dimensional glenohumeral relationship is imperative when planning and performing a total shoulder arthroplasty. There is, however, no consensus on which references should be used when studying this relationship. The purpose of the present study was to define the most suitable glenoid plane with normally distributed parameters, narrowest variability, and best reproducibility.

MATERIALS AND METHODS

Three-dimensional reconstruction CT scans were performed on 152 healthy shoulders. Four glenoid planes, each determined by three surgically accessible bony reference points, were determined. Two planes were triangular, with the same base defined by the most anterior and posterior point of the glenoid. The most inferior and the most superior point of the glenoid, respectively, define the top of Saller's inferior plane and the Saller's superior plane. The two other planes are formed by best-fitting circles. The circular max plane is defined by the superior tubercle, and two points at the distal third of the glenoid. The circular inferior plane is defined by three points at the rim of the inferior quadrants of the glenoid.

RESULTS

The parameters of all four planes behave normally. The humeral center of rotation is identically positioned for both the circular max and circular inferior plane (X = 91.71°/X = 91.66° p = 0.907 and Y = 90.83°/Y = 91.7° p = 0.054, respectively) and different for the Saller's inferior and Saller's superior plane (p ≤ 0.001). The circular inferior plane has the lowest variability to the coronal scapular plane (p < 0.001).

CONCLUSIONS

This study provides arguments to use the circular inferior glenoid plane as preferred reference plane of the glenoid.

Clinical Application of the "Glenoid Track" Concept for Defining Humeral Head Engagement in Anterior Shoulder Instability: A Preliminary Report

Background:

The optimal treatment of Hill-Sachs injuries is difficult to determine and is potentiated by the finding that a Hill-Sachs injury becomes more important in the setting of glenoid bone loss, making engagement of the humeral head on the glenoid inherently easier. The “glenoid track” concept was developed to biomechanically quantify the effects of a combined glenoid and humeral head bony defects on instability.

Purpose:

To clinically evaluate humeral head engagement on the glenoid by utilizing glenoid track measurements of both humeral head and glenoid bone loss.

Study Design:

Retrospective cohort.

Methods:

A total of 205 patients with recurrent anterior shoulder instability were evaluated, and of these, 140 patients (68%; 9 females [6%] and 131 males [94%]) with a Hill-Sachs lesion and a mean age of 27.6 years (range, 15-47 years; standard error of mean [SEM], 0.59) were included in the final magnetic resonance angiogram [MRA]) analysis. Bipolar bone loss measures of glenoid bone loss (sagittal oblique MRA) and multiple size measures of the Hill-Sachs injury (coronal, axial, and sagittal MRA) were recorded. Based on the extent of the bipolar lesion, patients were classified with glenoid track as either outside and engaging of the glenoid on the humeral head (OUT-E) or inside and nonengaging (IN-NE). The 2 groups were then compared with clinical evidence of engagement on examination under anesthesia (EUA) using video arthroscopy, number of dislocations, length of instability, and patient age.

Results:

The mean glenoid bone loss was 7.6% (range, 0%-29%; SEM, 1.20%), and 31 of 140 (22%) patients demonstrated clinical engagement on EUA. Radiographically, 19 (13.4%) patients were determined to be OUT-E, while 121 (86.6%) were IN-NE and not expected to engage. Of those 19 patients with suggested radiographic engagement (OUT-E), 16 (84.5%) had clinical evidence of engagement versus only 12.4% that clinically engaged (15/121) without radiographic evidence of engagement (IN-NE) (P < .001). Younger age and a greater number of recurrence events were jointly predictive of a patient being classified as OUT-E (11.8 vs 6.4 dislocations; P = .015).

Conclusion:

This study demonstrates that glenohumeral engagement was well predicted based on preoperative glenoid and humeral head bone loss measurements using the glenoid track method. In addition, younger age and a greater number of recurrences were predictive of engagement. The glenoid track concept may be important to fully assess the overall risk for engagement prior to surgery and may help guide surgical decision making such as bony augmentation procedures.

A new method to evaluate glenoid erosion in instable shoulder

Background

Methods

Results

Conclusions

Diagnostic accuracy of MRI in the measurement of glenoid bone loss

OBJECTIVE

The purpose of this study is to assess the accuracy of MRI quantification of glenoid bone loss and to compare the diagnostic accuracy of MRI to CT in the measurement of glenoid bone loss.

MATERIALS AND METHODS

MRI, CT, and 3D CT examinations of 18 cadaveric glenoids were obtained after the creation of defects along the anterior and anteroinferior glenoid. The defects were measured by three readers separately and blindly using the circle method. These measurements were compared with measurements made on digital photographic images of the cadaveric glenoids. Paired sample Student t tests were used to compare the imaging modalities. Concordance correlation coefficients were also calculated to measure interobserver agreement.

RESULTS

Our data show that MRI could be used to accurately measure glenoid bone loss with a small margin of error (mean, 3.44%; range, 2.06-5.94%) in estimated percentage loss. MRI accuracy was similar to that of both CT and 3D CT for glenoid loss measurements in our study for the readers familiar with the circle method, with 1.3% as the maximum expected difference in accuracy of the percentage bone loss between the different modalities (95% confidence).

CONCLUSION

Glenoid bone loss can be accurately measured on MRI using the circle method. The MRI quantification of glenoid bone loss compares favorably to measurements obtained using 3D CT and CT. The accuracy of the measurements correlates with the level of training, and a learning curve is expected before mastering this technique.

Operative guidelines for the reconstruction of the native glenoid plane: an anatomic three-dimensional computed tomography-scan reconstruction study

BACKGROUND

Reconstruction of the native plane in biconcave eroded glenoids is difficult. Nevertheless, accurate reconstruction of this plane is imperative for successful total shoulder arthroplasty. This study aims to determine guidelines that can increase the accuracy of glenoid component positioning.

METHODS

Three different circular planes were determined on 3-dimensional computed tomography (CT) scans of 152 healthy shoulders. First, the circular max (CM) plane is formed with the superior tubercle and 2 points, 1 anterior and 1 posterior, at the rim of the inferior third of the glenoid. Second, the circular inferior (CI) plane is formed by 3 points at the inferior 2 quadrants of the glenoid rim. Third, the circular minima (Cm) plane is formed with 3 points situated at the noneroded sector of the anterior glenoid. The angulation of the spinal scapular axis (SSA), the line between the most medial point of the scapular spine and the center of the three different glenoid planes, and the correlation coefficient between the radius of the circle and the length of SSA are calculated.

RESULTS

Angle SSA in the x-axis were 94°, 93°, 93° and in the y-axis were 95°, 111°, and 111° for CM, CI, and Cm, respectively. Correlation coefficient between the radius of the circle and the length of SSA: r = 0.69 for CM, r = 0.75 for CI, and r = 0.75 for Cm.

CONCLUSION

Three points situated at the native anterior glenoid can reconstruct, within 2° accuracy (95% confidence interval, 1.8°-2.3°), the CI plane. A relationship exists between the radii of the 3 glenoid circles and the width of the scapula (SSA length).

The evaluation of arthroscopic remplissage by high-resolution magnetic resonance imaging

BACKGROUND

Arthroscopic remplissage is a novel procedure recently advocated for the treatment of large Hill-Sachs lesions with recurrent anterior glenohumeral instability. We have shown previously that infraspinatus tenodesis and Bankart repair reduce the risk of recurrent instability in high-risk patients. The ability to perform this procedure arthroscopically and without the need for bone grafting or an open approach makes this an appealing alternative to more traditional techniques.

PURPOSE

To evaluate and characterize the postoperative appearance of the remplissage procedure on high-resolution magnetic resonance imaging (MRI) and to correlate these findings to clinical outcome (Western Ontario Shoulder Instability [WOSI] score, range of motion).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

In patients who had undergone arthroscopic remplissage for recurrent glenohumeral instability with large Hill-Sachs defects, images were acquired with a 3-T protocol (and reviewed by 2 musculoskeletal radiologists) with the shoulder in the abduction-external rotation (ABER) and neutral positions at the time of the latest clinical examination. Measured parameters included signal intensity of tissue within the prior defect, signal intensity of the residual infraspinatus, degree of fatty infiltrate and muscle atrophy as a percentage of fat signal versus muscle signal (Goutallier grade), presence of marrow edema, and number of anchors in the defect. Functional scores were obtained with the WOSI questionnaire, and comprehensive range of motion data were recorded with a goniometer.

RESULTS

In 11 patients with an average clinical follow-up of 18.0 months (range, 8.8-27.2 months), the average size of the Hill-Sachs deformity was 334.3 mm(3) (range, 93.6-825.1 mm(3)). The percentage of the deformity filled in with tendon was 75% to 100%, and the degree of atrophy was 0% to 25% for all patients studied. No defects were left unfilled. Two patients had granulation tissue filling the lesion, and 3 patients had fibrous tissue, while the rest of the patients had the MRI appearance of both granulation and fibrous tissue. Four of 9 patients had tendinopathy or partial tears of the residual infraspinatus tendon insertion, and 1 patient demonstrated residual bone marrow edema. The average number of anchors used was 1.4 (range, 1-3). The average WOSI score was 74.3% (range, 41.6%-99.2%), with an average external rotation loss of 5.8° (range, 0°-22°). One patient had recurrence of instability.

CONCLUSION

Our data suggest that there is evidence of tendon incorporation and fill into the Hill-Sachs defect following arthroscopic remplissage at 8 months and beyond. Although MRI findings did not correlate with the clinical findings, patients were satisfied with the procedure and demonstrated minimal loss of external rotation (average, 5.8°) at early follow-up.

The importance of the recognition and treatment of glenoid bone loss in an athletic population

CONTEXT

Osseous injury to the glenoid is increasingly being recognized as one of the most important aspects in the successful management of recurrent shoulder instability. Proper early recognition of glenoid bone injury in the setting of recurrent instability will lead to successful nonoperative and operative decision making, particularly in the athletic patient.

EVIDENCE ACQUISITION

We conducted a MEDLINE search on shoulder instability from 2000 to 2010. The emphasis was placed on patient-oriented Level 1 literature from 2000 to 2010.

RESULTS

After a traumatic anterior dislocation of the shoulder, the most common structural injury is an avulsion of the anteroinferior capsulolabrum, which is also known as a Bankart lesion. If this specific injury is accompanied by an associated fracture in the glenoid rim, the term bony Bankart lesion is more applicable. With diminished articular constraints, the glenohumeral joint is subject to recurrent instability, thereby potentiating the bony injury cycle. Additionally, patients with osseous defects usually complain of instability within the midranges of motion, or they recall a progression of instability. If glenoid bone loss is present, the humeral head often easily subluxates over the glenoid in the midranges of abduction (30°-90°) and lower levels of external rotation. Imaging workup should begin with plain radiographs, but advanced imaging should be obtained if there is any suspicion of bone loss. Treatment includes both nonoperative and operative interventions.

CONCLUSIONS

Estimation of the amount of glenoid bone loss and the failure of nonoperative care is essential for guiding management, patient expectations, and surgical decision making.

Calculating anterior glenoid bone loss using the Bernageau profile view

OBJECTIVE

To determine if it is possible to measure glenoid bone loss by using the Bernageau view and to compare it to a 3D CT scan.

MATERIALS AND METHODS

Fifty healthy subjects with a mean age of 34 ± 8 years old and 31 (62 %) male were submitted to the Bernageau view X-ray of both shoulders. Three blinded evaluators measured the distance between the posterior and anterior glenoid rim. Ten patients with multiple episodes of unilateral traumatic anterior shoulder dislocation with a mean age of 34 ± 9.1 years old and 90 % male were submitted to the same X-ray technique to determine the percentage of glenoid bone loss. They were also submitted to a bilateral 3D CT scan to be compared to the radiographs.

RESULTS

In the 50 asymptomatic subjects, the AP distance was 24.48 mm ± 3.32 mm in the left shoulder and 24.82 mm ± 3.16 mm in the right shoulder. Comparing the X-ray study and the 3D CT scan of the ten patients with multiple episodes, there was no significant statistical difference of the AP normal distance in both methods (p = 0.646), the AP erosion distance (p = 0.386), as well as the percentage of bone loss (p = 0.513). Moreover, the differences between the percentages of bone loss in the X-ray, compared with the 3D CT scan were, on average 2.28 % (range 0 to 6.05 %).

CONCLUSIONS

The Bernageau radiographic view is an accurate and reproducible technique for measuring the presence of glenoid erosion, with similar results when compared to the 3D CT scan.

Restoration of anterior glenoid bone defects in posttraumatic recurrent anterior shoulder instability using the J-bone graft shows anatomic graft remodeling

BACKGROUND

The J-bone graft technique has previously been reported for anatomic restoration of the bony glenoid surface in cases of posttraumatic recurrent anterior shoulder instability with significant glenoid bone loss.

PURPOSE

To analyze the physiological remodeling process of the J-bone graft over time.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Thirty-one consecutive patients treated with anatomic glenoid restoration surgery using the J-bone graft for posttraumatic recurrent anterior shoulder instability with a significant bony glenoid defect were included in this study. Twenty patients received 3-dimensional computed tomography scans of the affected shoulder preoperatively, postoperatively, and at 1-year follow-up. On "en face" views of the glenoid, the change over time of the glenoid diameter, glenoid area, and glenoid defect size in relation to a best-fit circle indicating 100% was measured.

RESULTS

The average glenoid diameter increased from 81.0% preoperatively to 110.4% postoperatively (P < .001). At 1-year follow-up, the diameter had decreased significantly to 100.6% (P < .001), which is concordant to a theoretical perfect glenoid diameter of 100% (P = .73). The average glenoid surface area increased from 80.8% preoperatively to 110.0% postoperatively (P < .001). At 1-year follow-up, a decrease to 102.2% (P < .005) was measured, which again is close to a theoretical perfect glenoid surface area of 100% (P = .15). By applying the J-bone graft, the average missing surface area of the glenoid was reduced from 19.2% preoperatively to 3.9% postoperatively (P < .001). At 1-year follow-up, an average of 3.6% was calculated, indicating no statistically significant change over time (P = .90).

CONCLUSION

Anatomic glenoid reconstructive surgery using the J-bone graft technique benefits from a physiological remodeling process, molding the bone graft closely into the original shape of an uninjured anterior glenoid rim. While parts of the graft lying inside the projected former surface area of the glenoid are preserved, the parts lying outside are resorbed over time, suggestive of strain-adapted graft remodeling.

Area-based determination of bone loss using the glenoid arc angle

In patients with anterior glenohumeral instability, the most commonly observed osseous defect involves the anterior portion of the inferior glenoid. The amount of glenoid bone loss guides surgical treatment, with progressively larger defects not being amenable to arthroscopic soft-tissue procedures. Currently, there is no universally accepted method of quantifying glenoid bone loss. Two-dimensional area-based methods and 1-dimensional methods of measuring bone loss have both been described but cannot be used interchangeably. The surface area of a glenoid bony defect is a more comprehensive descriptor of its magnitude than the 1-dimensional width of the defect. Calculating surface area can be challenging. We describe a method of quantifying glenoid bone loss using a glenoid arc angle that corresponds to the surface area of the defect. The arc angle is easily measured by use of commonly used imaging software tools and is independent of the size of the glenoid or defect orientation. This method may prove valuable in preoperative planning for patients with anterior glenohumeral instability.

Comparisons of glenoid bony defects between normal cadaveric specimens and patients with recurrent shoulder dislocation: an anatomic study

BACKGROUND

The location and degree of bony defects that can affect clinical outcomes remains controversial in recurrent shoulder dislocation. The purpose of this study was to define the most common location of glenoid bony defects in patients with recurrent shoulder dislocation.

MATERIALS AND METHODS

We analyzed the shape and aspect ratio of 44 glenoids from deceased donors. Glenoid size was analyzed using a 3-dimensional (3D) computed tomography (CT) scan in 24 patients with recurrent shoulder dislocation who underwent arthroscopic Bankart repair. We measured the distances from the center of the longitudinal axis of the glenoid to the anterior glenoid rim at 9 positions, 10° apart, from 3:00 to 6:00 o'clock positions in the cadaver and patient groups. We compared the quantification of glenoid defects in the 24 patients using the 3D CT scan. A predictive model based on a discriminant analysis was developed.

RESULTS

The largest length differences of the glenoid were at the 3:20 o'clock position. When percentage of bone antidefect of the 3:20 o'clock position was used, the model predicted the existence of a defect with 89.7% hit ratio.

CONCLUSIONS

The major direction of the glenoid defect was in a more anterior position rather than the anteroinferior glenoid in patients with recurrent shoulder dislocation. The 3:20 o'clock position was most common location of glenoid defect in shoulder instability. This pattern of bone loss should be considered by the surgeon when operating on these patients, especially when performing arthroscopic procedures for Bankart repair or bone block operations to the glenoid.

Recurrent anterior shoulder instability: accuracy of estimations of glenoid bone loss with computed tomography is insufficient for therapeutic decision-making

OBJECTIVE

To evaluate the reliability of glenoid bone loss estimations based on either axial computed tomography (CT) series or single sagittal ("en face" to glenoid) CT reconstructions, and to assess their accuracy by comparing with actual CT-based bone loss measurements, in patients with anterior glenohumeral instability.

MATERIALS AND METHODS

In two separate series of patients diagnosed with recurrent anterior glenohumeral instability, glenoid bone loss was estimated on axial CT series and on the most lateral sagittal (en face) glenoid view by two blinded radiologists. Additionally, in the second series of patients, glenoid defects were measured on sagittal CT reconstructions by an independent observer.

RESULTS

In both series, larger defects were estimated when based on sagittal CT images compared to axial views. In the second series, mean measured bone loss was 11.5% (SD = 6.0) of the total original glenoid area, with estimations of 9.6% (SD = 7.2) and 7.8% (SD = 4.2) for sagittal and axial views, respectively. Correlations of defect estimations with actual measurements were fair to poor; glenoid defects tended to be underestimated, especially when based on axial views.

CONCLUSION

CT-based estimations of glenoid bone defects are inaccurate. Especially for axial views, there is a high chance of glenoid defect underestimation. When using glenoid bone loss quantification in therapeutic decision-making, measuring the defect instead of estimating is strongly advised.

Analysis of risk factors for glenoid bone defect in anterior shoulder instability

BACKGROUND

Glenoid bone defect is frequently associated with anterior shoulder instability and is considered one of the major causes of recurrence of instability after shoulder stabilization.

HYPOTHESIS

Some risk factors are significantly associated with the presence, size, and type of glenoid bone defect.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

One hundred sixty-one patients affected by anterior shoulder instability underwent morphologic evaluation of the glenoid by computed tomography scans to assess the presence, size, and type of glenoid bone defect (erosion or bony Bankart lesion). Bone loss greater than 20% of the area of the inferior glenoid was considered "critical" bone defect (at risk of recurrence). Outcomes were correlated with the following predictors: age, gender, arm dominance, frequency of dislocation, age at first dislocation, timing from first dislocation, number of dislocations, cause of first dislocation, generalized ligamentous laxity, type of sport, and manual work.

RESULTS

Glenoid bone defect was observed in 72% of the cases. Presence of the defect was significantly associated with recurrence of dislocation compared with a single episode of dislocation, increasing number of dislocations, male gender, and type of sport. Size of the defect was significantly associated with recurrent dislocation, increasing number of dislocations, timing from first dislocation, and manual work. Presence of a critical defect was significantly associated with number of dislocations and age at first dislocation. Bony Bankart lesion was significantly associated with male gender and age at first dislocation.

CONCLUSION

The number of dislocations and age at first dislocation are the most significant predictors of glenoid bone loss in anterior shoulder instability.

Comparison between 2D and 3D computed tomography evaluation of glenoid bone defect in unilateral anterior gleno-humeral instability

PURPOSE

This study evaluated the agreement between 2D and 3D computed tomography (CT) measurements in identifying the size and type of glenoid-bone defect in anterior glenohumeral instability.

MATERIALS AND METHODS

One hundred patients affected by unilateral anterior glenohumeral instability underwent a CT of both shoulders. Images were processed with both 2D [multiplanar reconstruction (MPR)] and 3D [volumerendering (VR)] methods. The area of the missing glenoid was calculated in comparison with the healthy glenoid and expressed as a percentage. Agreement between the two measurements was assessed according to the Bland-Altman method; a 5% mean difference was considered as clinically relevant.

RESULTS

Analysis of agreement between MPR and VR measurements of the percentage of missing glenoid showed a mean difference equal to 0.62%±1.96%. Percent agreement between the two measurements in detecting the presence of bone defect was 97% (p<0.0001). Percent agreement between the two measurements in discriminating the type of bone defect was 97% (p<0.0001).

CONCLUSIONS

Agreement between 2D (MPR) and 3D (VR) CT measurements to identify the size and type of glenoid-bone defect in anterior glenohumeral instability was so high that the two measurements can be considered interchangeable.

Management of failed instability surgery: how to get it right the next time

Traumatic anterior shoulder dislocations are the most frequent type of joint dislocation and affect approximately 1.7% of the general population. The literature supports the consideration of primary stabilization in high-risk patients because of reported recurrences as high as 80% to 90% with nonoperative treatment regimens. Successful stabilization of anterior glenohumeral instability relies on not only good surgical techniques but also careful patient selection. Failure rates after open and arthroscopic stabilization have been reported to range from 2% to 8% and 4% to 13%, respectively. Recurrent shoulder instability leads to increased morbidity to the patient, increased pain, decreased activity level, prolonged time away from work and sports, and a general decrease in quality of life. This article reviews the potential pitfalls in anterior shoulder stabilization and discusses appropriate methods of addressing them in revision surgery.

Arthroscopic management of anterior instability: pearls, pitfalls, and lessons learned

Despite advances in the understanding of anterior shoulder instability, failure rates after open and arthroscopic surgery have been reported to be as high as 30%. In general, a successful operative outcome for patients with shoulder instability requires the surgeon to perform a complete preoperative evaluation, a thorough diagnostic arthroscopy to evaluate for concomitant co-pathology, and implement an effective postoperative therapy program tailored to the repair strategy. In addition to the Bankart lesion, the treating surgeon must be aware of other co-pathologies, such as the HAGL lesion, ALPSA lesion, and SLAP tears, that can occur in concert with capsular pathology and present as potential barriers to a successful outcome. This article focuses specifically on the pearls and pitfalls that are important to recognize in the preoperative workup, intraoperative evaluation, and arthroscopic surgery to optimize surgical outcomes for anterior instability.

Normalization of glenohumeral articular contact pressures after Latarjet or iliac crest bone-grafting

BACKGROUND

Multiple bone-grafting procedures have been described for patients with glenoid bone loss and shoulder instability. The purpose of this study was to investigate the alterations in glenohumeral contact pressure associated with the placement and orientation of Latarjet or iliac crest bone graft augmentation and to compare the amount of glenoid bone reconstruction with two coracoid face orientations.

METHODS

Twelve fresh-frozen cadaver shoulders were tested in static positions of humeral abduction (30 degrees , 60 degrees , and 60 degrees with 90 degrees of external rotation) with a 440-N compressive load. Glenohumeral contact pressure and area were determined sequentially for (1) the intact glenoid; (2) a glenoid with an anterior bone defect involving 15% or 30% of the glenoid surface area; (3) a 30% glenoid defect treated with a Latarjet or iliac crest bone graft placed 2 mm proud, placed flush, or recessed 2 mm in relation to the level of the glenoid; and (4) a Latarjet bone block placed flush and oriented with either the lateral (Latarjet-LAT) or the inferior (Latarjet-INF) surface of the coracoid as the glenoid face. The amount of glenoid bone reconstructed was compared between the Latarjet-LAT and Latarjet-INF conditions.

RESULTS

Bone grafts in the flush position restored the mean peak contact pressure to 116% of normal when the iliac crest bone graft was used (p < 0.03 compared with the pressure with the 30% defect), 120% when the Latarjet-INF bone block was used (p < 0.03), and 137% when the Latarjet-LAT bone block was used (p < 0.04). Use of the Latarjet-LAT bone block resulted in mean peak pressures that were significantly higher than those associated with the iliac crest bone graft (p < 0.02) or the Latarjet-INF bone block (p < 0.03) at 60 degrees of abduction and 90 degrees of external rotation. With the bone grafts placed in a proud position, peak contact pressure increased to 250% of normal (p < 0.01) in the anteroinferior quadrant and there was a concomitant increase in the posterosuperior glenoid pressure to 200% of normal (p < 0.02), indicating a shift posteriorly. Peak contact pressures of bone grafts placed in a recessed position revealed high edge-loading. Augmentation with the Latarjet-LAT bone block led to restoration of the glenoid articular contact surface from the 30% defect state to a 5% defect state. Augmentation of the 30% glenoid defect with the Latarjet-INF bone block resulted in complete restoration to the intact glenoid articular surface area.

CONCLUSIONS

Glenohumeral contact pressure is optimally restored with a flush iliac crest bone graft or with a flush Latarjet bone block with the inferior aspect of the coracoid becoming the glenoid surface. Bone grafts placed in a proud position not only increase the peak pressure anteroinferiorly, but also shift the articular contact pressure to the posterosuperior quadrant. Glenoid bone augmentation with a Latarjet bone block with the inferior aspect of the coracoid as the glenoid surface resulted in complete restoration of the 30% anterior glenoid defect to the intact state. These findings indicate the clinical utility of a flush iliac crest bone graft and utilization of the inferior surface of the coracoid as the glenoid face for glenoid bone augmentation with a Latarjet graft.

Reliability of the glenoid plane

HYPOTHESIS

The purpose of this study was to investigate the 3-dimensional (3-D) orientation of the glenoid and scapular planes. Different definitions of the glenoid plane were used and different planes measured, and we hypothesed that the 3-D plane with the least variation would be best to define the most reliable glenoid plane.

METHODS

We studied 150 CT scans from nonpathological shoulders from patients between 18 and 80. The scapular plane and 5 different glenoid planes were determined: inferior, anterior, posterior, superior, and neutral. All plane versions and inclination angles were measured. Because all examinations were done in a standardized position to the coronal, sagittal, and transverse planes of the body, the scapular plane could be defined versus the coronal, sagittal, and transverse planes of the body.

RESULTS

The version (mean, 3.76) of the inferior glenoid plane showed a significantly lower standard deviation than the version of the anterior (P < .001), posterior (P=.001), and superior (P=.001) glenoid plane (ANOVA). For inclination all planes have a similar variance. The scapular plane was different between gender (P=.022) and correlated with age.

CONCLUSION

This study showed that the retroversion of the inferior glenoid is reasonably constant. The osseous anthropometry of the inferior glenoid can offer a reproducible point of reference to be used in prosthetic surgery of the shoulder.

Intra-observer and interobserver reliability of the 'Pico' computed tomography method for quantification of glenoid bone defect in anterior shoulder instability

OBJECTIVE

To evaluate the intra-observer and interobserver reliability of the 'Pico' computed tomography (CT) method of quantifying glenoid bone defects in anterior glenohumeral instability.

MATERIALS AND METHODS

Forty patients with unilateral anterior shoulder instability underwent CT scanning of both shoulders. Images were processed in multiplanar reconstruction (MPR) to provide an en face view of the glenoid. In accordance with the Pico method, a circle was drawn on the inferior part of the healthy glenoid and transferred to the injured glenoid. The surface of the missing part of the circle was measured, and the size of the glenoid bone defect was expressed as a percentage of the entire circle. Each measurement was performed three times by one observer and once by a second observer. Intra-observer and interobserver reliability were analyzed using intraclass correlation coefficients (ICCs), 95% confidence intervals (CIs), and standard errors of measurement (SEMs).

RESULTS

Analysis of intra-observer reliability showed ICC values of 0.94 (95% CI = 0.89-0.96; SEM = 1.1%) for single measurement, and 0.98 (95% CI = 0.96-0.99; SEM = 1.0%) for average measurement. Analysis of interobserver reliability showed ICC values of 0.90 (95% CI = 0.82-0.95; SEM = 1.0%) for single measurement, and 0.95 (95% CI = 0.90-0.97; SEM = 1.0%) for average measurement.

CONCLUSION

Measurement of glenoid bone defect in anterior shoulder instability can be assessed with the Pico method, based on en face images of the glenoid processed in MPR, with a very good intra-observer and interobserver reliability.

A new arthroscopic technique to determine anterior-inferior glenoid bone loss: validation of the secant chord theory in a cadaveric model

PURPOSE

The accuracy of a previously described method using the glenoid bare spot (GBS) as a reference point was compared with a new method using the secant chord theory (SCT), which relies on the circular geometry of the inferior glenoid to calculate bone loss.

METHODS

In 7 embalmed cadaveric shoulders a digital image of the glenoid face was used to calculate the area of the best-fit circle of the inferior glenoid. Osteotomy templates from the 3-o'clock to 6-o'clock position were created to make a simulated anterior-inferior bone defect of 12.5% and 25% of the area of the circle. Measurements were taken with an arthroscopic probe from 2 simulated posterior portal positions (9 and 10 o'clock) by use of 2 techniques-SCT and GBS-in the intact, 12.5% loss, and 25% loss states.

RESULTS

In the intact state, measurements showed a mean SCT loss of 4.1% and GBS loss of 4.4%. In the 12.5% loss state, mean percent bone loss with GBS was 23.1% compared with 14.8% with SCT (P = .0001) at the 10-o'clock portal and 22.2% compared with 15.9% (P = .006) at the 9-o'clock portal. In the 25% loss state, mean percent bone loss with GBS was 31.5% compared with 26.6% with SCT (P = .002) at the 10-o'clock portal and 30.4% compared with 28.9% (P = .48) at the 9-o'clock portal.

CONCLUSIONS

The SCT is shown to be a more accurate method of determining glenoid bone loss in an arthroscopic model; however, additional mathematic calculations are necessary. As shown in the intact state, there is an inherent small error of approximately 4% when arthroscopically determining bone loss.

CLINICAL RELEVANCE

The technique may aid the clinician in quantifying glenoid bone loss and help determine when bone augmentation may be advisable.

[Anterior glenoid rim defects of the shoulder]

Bony instability of the shoulder due to glenoid defects has recently received increasing attention. Glenoid defects can be divided into acute fragment-type lesions (type I), chronic fragment-type lesions (type II) and glenoid bone loss without a bony fragment (type III). The diagnosis and classification are mainly based on imaging methods including a radiographic instability series and/or computed tomography. The management of anterior glenoid rim lesions depends on many factors including the clinical presentation, type of lesion, concomitant pathology as well as age and functional demands of the patient. If bony-mediated instability is present, surgery is indicated. In the majority of cases fragment-type lesions can be successfully treated using either arthroscopic or open reconstruction techniques.Small erosion-type lesions can also be managed via soft-tissue procedures, whereas large erosion-type lesions with significant bone loss may necessitate bone-grafting procedures (autologous iliac crest or coracoid transfer) to restore glenoid concavity and shoulder stability. Although glenoid bone grafting is usually performed via an open approach, recent clinical studies have shown that it can be successfully managed by advanced arthroscopic techniques.

Glenoid bone deficiency in recurrent anterior shoulder instability: diagnosis and management

Recurrent anterior shoulder instability may result from a spectrum of overlapping, often coexistent factors, one of which is glenoid bone loss. Untreated, glenoid bone loss may lead to recurrent instability and poor patient satisfaction. Recent studies suggest that the glenoid rim is altered in up to 90% of shoulders with recurrent instability, thus underscoring the need for careful diagnosis, quantification, and preoperative evaluation. Biomechanical and clinical studies offer criteria that may be used in both primary and revision settings to judge whether shoulder stability is compromised by a bony defect. Along with patient activity level, these criteria can help guide the surgeon in selecting treatment options, which range from nonsurgical care to isolated soft-tissue repair as well as various means of bony reconstitution.

Bony instability of the shoulder

Instability of the shoulder is a common problem treated by many orthopaedists. Instability can result from baseline intrinsic ligamentous laxity or a traumatic event-often a dislocation that injures the stabilizing structures of the glenohumeral joint. Many cases involve soft-tissue injury only and can be treated successfully with repair of the labrum and ligamentous tissues. Both open and arthroscopic approaches have been well described, with recent studies of arthroscopic soft-tissue techniques reporting results equal to those of the more traditional open techniques. Over the last decade, attention has focused on the concept of instability of the shoulder mediated by bony pathology such as a large bony Bankart lesion or an engaging Hill-Sachs lesion. Recent literature has identified unrecognized large bony lesions as a primary cause of failure of arthroscopic reconstruction for instability, a major cause of recurrent instability, and a difficult diagnosis to make. Thus, although such bony lesions may be relatively rare compared with soft-tissue pathology, they constitute a critically important entity in the management of shoulder instability. Smaller bony lesions may be amenable to arthroscopic treatment, but larger lesions often require open surgery to prevent recurrent instability. This article reviews recent developments in the diagnosis and treatment of bony instability.

Quantification of a glenoid defect with three-dimensional computed tomography and magnetic resonance imaging: a cadaveric study

Bone loss of the glenoid is a common finding in anterior glenohumeral instability. Several methods to measure the size of a glenoid defect have been described but have not been validated. In this study, 14 cadaver glenoids with a randomly created anteroinferior glenoid defect were used for validation of the so-called circle method. Measurements were done by 2 researchers on digital photographs, 3-dimensional (3D) computed tomography (CT) scans, and magnetic resonance images (MRI). The correlation coefficient (r(2)) for comparing measurements from the digital photographs with the CT scans was 0.97 for researcher 1 and 0.90 for researcher 2. When they compared digital images with MRI, the r(2) was 0.93 for researcher 1 and 0.92 for researcher 2. No statistical differences were found between the 2 researchers. The circle method is a simple method for preoperative quantification of a glenoid defect. Measurements can be done with 3D CT scans as well as MRI.