Techniques to evaluate glenoid bone loss

Evaluation of the diagnostic performance of the simple method of computed tomography in the assessment of patients with shoulder instability: a prospective cohort study

Background

Physical examinations may reveal the instability of a glenohumeral joint but cannot diagnose the bony Bankart lesions. Soft tissue Bankart lesion cannot be visualized on traditional radiogram. Magnetic resonance images have high cost and availability issues. The purpose of the study was to access the diagnostic performance of the Computed Tomography (CT) in the assessment of patients with shoulder instability and to diagnose the Bankart and bony Bankart lesions.

Methods

A total of 145 patients with shoulder instability were included in the study. Patients were subjected to clinical examination tests, traditional radiography, and CT. Two orthopedic surgeons, two engineers (trained in musculoskeletal imaging), and two physiotherapists have analyzed the radiological images, CT scans, and the clinical examination tests respectively. The Chi-square test or one-way ANOVA/ Dunnett Multiple comparisons test was performed at 99% of confidence level.

Results

Sensitivity (0.972 ± 0.18 vs. 1, p = 0.11) and accuracy (0.942 ± 0.17 vs. 1, p < 0.0001, q = 3.88) for the clinical examination tests combining the traditional radiological images were same to CT. However, the clinical examination tests combining the traditional radiological images had more inconclusive results (5 vs. 1), false-positive results (6 vs. 5), and false negative results (4 vs. 1) than CT. The area that detects the Bankart and bony Bankart lesions at least one time for CT was higher than that of the clinical examination tests combining the traditional radiological images.

Conclusion

CT should be considered for evaluation in patients with shoulder instability and suspected Bankart and bony Bankart lesions.

Trial registration

Researchregistry3990 dated 15 December 2014 (www.researchregistry.com).

Bone Loss and Glenohumeral Instability

Glenohumeral instability secondary to glenohumeral bone loss presents a complex problem to the treating surgeon because of the complex biomechanics of the glenohumeral joint and its reliance on numerous dynamic and static stabilizers. The role of glenoid bone loss, specifically inferior-anterior glenoid bone loss, has been well characterized in the setting of recurrent unidirectional instability with greatly improved clinical results when following an algorithmic reconstructive approach to the location and percentage of overall bone loss. Furthermore, as the role of bipolar bone loss in the setting of glenohumeral engagement becomes more apparent, surgeons can more effectively address those lesions contributing to the recurrent instability. As such, surgeons should carefully and critically asses patients with recurrent anterior instability to optimize patient clinical outcomes.

Critical Glenoid Bone Loss in Posterior Shoulder Instability

BACKGROUND

There is currently no consensus regarding the amount of posterior glenoid bone loss that is considered critical. Critical bone loss is defined as the amount of bone loss that occurs in which an isolated labral repair will not sufficiently restore stability.

PURPOSE

The purpose is to identify the critical size of the posterior defect.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven cadaveric shoulders were tested. With the use of a custom robot device, a 50-N compressive force was applied to the glenohumeral joint, and the peak force that was required to translate the humeral head posteriorly and the lateral displacement that occurred with translation were measured. The defect size was measured as a percentage of the glenoid width. Testing was performed in 11 conditions: (1) intact glenoid and labrum, (2) simulated reverse Bankart lesion, (3) the reverse Bankart lesion repaired, (4) a 10% defect, (5) the reverse Bankart lesion repaired, (6) a 20% defect, (7) the reverse Bankart lesion repaired, (8) a 30% defect, (9) the reverse Bankart lesion repaired, (10) a 40% defect, and (11) the reverse Bankart repaired.

RESULTS

Force and displacement decreased as the size of the osseous defect increased. The mean peak force that occurred with posterior displacement in specimens with a glenoid defect ≥20% and a reverse Bankart repair (13 ± 9 N) was significantly lower than the peak force that occurred in specimens with an isolated reverse Bankart repair (22 ± 10 N) ( P = .0451). In addition, the mean lateral displacement was significantly less in the specimens with a 20% glenoid defect and a reverse Bankart repair (0.61 ± 0.57 mm) compared with the lateral displacement that occurred in specimens with an isolated reverse Bankart repair (1.6 ± 0.78 mm) ( P = .0058).

CONCLUSION

An osseous defect that is ≥20% of the posterior glenoid width remains unstable after isolated reverse Bankart repair.

CLINICAL RELEVANCE

A bony restoration procedure of the glenoid may be necessary in shoulders with a posterior glenoid defect that is ≥20% of the glenoid width.

Acute Versus Delayed Magnetic Resonance Imaging and Associated Abnormalities in Traumatic Anterior Shoulder Dislocations

Background:

The delayed management of patients with shoulder instability may increase the prevalence and severity of concomitant intra-articular shoulder injuries resulting from persistent subluxations and dislocations.

Hypothesis:

Patients with a longer delay from the initial dislocation event to undergoing magnetic resonance imaging (MRI) or magnetic resonance arthrography will demonstrate more subluxations or dislocations and a greater amount of intra-articular shoulder damage.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

We performed a retrospective review of 89 patients from a single institution with clinically and radiographically confirmed primary traumatic anterior shoulder dislocations. Patients were divided into 2 groups: those undergoing MRI less than 6 months (n = 44; LT6) or greater than 6 months (n = 45; GT6) from the initial dislocation event. The MRI assessment included evaluation of soft tissue injuries, including the labrum, capsule, rotator cuff, and cartilage damage severity along with bone loss.

Results:

The delayed MRI group (GT6) demonstrated a greater degree of intra-articular abnormalities compared to the early MRI group (LT6). A greater percentage of superior labral anterior-posterior (SLAP) tears (58% vs 34%, respectively) and cartilage damage (73% vs 27%, respectively) was present in the GT6 group compared to the LT6 group. Cartilage damage was 18% mild, 7% moderate, and 2% severe for the LT6 group as compared to 38% mild, 31% moderate, and 4% severe for the GT6 group. Additionally, more recurrent shoulder dislocations were seen in the GT6 group (n = 6) compared to the LT6 group (n = 2). In the LT6 group, there were more rotator cuff tears (50% vs 24%, respectively) and capsular tears (25% vs 9%, respectively) than the GT6 group. There was no difference in anterior glenoid bone loss, glenoid version, or humeral head subluxation between the 2 groups.

Conclusion:

Patients who undergo MRI greater than 6 months from the time of primary or initial shoulder dislocation had significantly more recurrent shoulder instability events and demonstrated a greater incidence and severity of intra-articular abnormalities, including SLAP tears, posterior labral tears, and anterior glenoid cartilage damage.

Radiographic Evaluation of Patients with Anterior Shoulder Instability

PURPOSE OF REVIEW

Injuries to the labrum, joint capsule (in particular the inferior glenohumeral ligament), cartilage, and glenoid periosteum are associated with anterior shoulder instability. The goal of this review is to provide common radiographic images and findings in patients with anterior shoulder instability. Furthermore, we will demonstrate the best methods for measuring anterior glenoid bone loss.

RECENT FINDINGS

Magnetic resonance (MR) imaging is highly relied upon for evaluating anterior shoulder instability and can diagnose soft tissue injuries with high sensitivity. While 3D computed tomography (CT) scan has been considered the optimal tool for evaluating osseous defects, certain MR imaging sequences have been shown to have similar diagnostic accuracy. Repair of Bankart lesions is critical to stabilizing the shoulder, and in the recent years, there has been an increasing focus on imaging to accurately characterize and measure glenoid bone loss to properly indicate patients for either arthroscopic repair or anterior bony reconstruction. Furthermore, Hill-Sachs lesions are commonly seen with shoulder instability, and importance must be placed on measuring the size and depth of these lesions along with possible engagement, as these factors will dictate management. The labral-ligamentous complex and rotator cuff are primary stabilizers of the shoulder. With anterior shoulder instability, the labrum is frequently injured. MRI with an arthrogram or provocative maneuvers is the gold standard for diagnosis. Various imaging modalities and methods can be performed to identify and measure Bankart and Hill-Sachs lesions, which can then be used for surgical planning and treating shoulder instability.

Imaging of the Unstable Shoulder

Background:

Unstable shoulder can occur in different clinical scenarios with a broad spectrum of symptoms and presentations: first-time (or recurrent) traumatic acute shoulder anterior dislocation or chronic anterior instability after repeated dislocations.

Imaging in unstable shoulder is fundamental for choosing the right treatment preventing recurrence.

The goal of imaging depends on clinical scenario and patient characteristics.

Method:

Careful selection and evaluation of the imaging procedures is therefore essential to identify, characterize and quantify the lesions. Proper imaging in unstable shoulder cases is critical to the choice of treatment to prevent recurrence, and to plan surgical intervention.

Results:

In acute setting, radiographs have to roughly detect and characterize the bone defects present. At about 7 days, it is recommended to perform a MR to demonstrate lesions to labrum and/or ligaments and bone defects: in acute setting, the MRA is not necessary, because of effusion and hemarthrosis that behave as the contrast medium.

In recurrence, it is fundamental not only to detect lesions but characterize them for planning the treatment. The first study to do is the MRI (with a magnetic field of at least 1.5 Tesla), and if possible MRA, above all in younger patients. Then, on the basis of the pathologic findings as bipolar lesion or severity of bone defects, CT can be performed. PICO method on 2D or 3D CT is helpful if you need to study a glenoid bone loss, with the “en face view” of glenoid, while a 3D CT reconstruction with the humeral head “en face view” is the gold standard to assess an Hill-Sachs lesion.

Conclusion:

The clinical diagnoses of anterior shoulder instability can be different and acknowledgement of imaging findings is essential to guide the treatment choice.

Imaging features are quite different in chronic than in acute scenario. This requires appropriate indications of many different imaging techniques.

Interobserver and intraobserver variability of glenoid track measurements

BACKGROUND

A method of assessing combined glenoid and humeral bone loss in traumatic shoulder instability with an associated treatment protocol was recently published. The aim of this study was to investigate its reliability and reproducibility.

METHODS

Seventy-one patients with unilateral anteroinferior shoulder instability underwent computed tomography scans, from which 3-dimensional images were derived. En face views of both glenoid fossae and with 3 views of the humeral head were provided to 4 assessors to determine interobserver reliability. From these measurements, the shoulder was assigned a treatment classification. Two observers repeated their assessments 1 month later to determine intraobserver reliability. For each measurement, the mean coefficient of variability was calculated.

RESULTS

Assessment of glenoid bone loss showed good interobserver (4 observers agreeing in 90.1% of cases) and also good intraobserver agreement (94% and 96%). There was a poor level of interobserver reliability regarding the on-track or off-track classification (72%). Intraobserver reliability for this measurement was less variable (90% and 80%). There was a poor level of agreement between observers (65%) regarding treatment classification. The coefficient of variability for the Hill-Sachs lesion measured 19.2%, indicating a high level of variability for this measurement compared with <4% for all other measures.

CONCLUSION

Linear bone loss on the glenoid can be measured reliably and reproducibly; however, evaluation of Hill-Sachs lesions demonstrates a high level of variability, and poor interobserver reliability.

Tomographic evaluation of Hill-Sachs lesions: is there a correlation between different methods of measurement?

BACKGROUND

Several methods are currently available to evaluate and quantify the glenoid or humeral bone loss; however, none is universally accepted, particularly in the case of Hill-Sachs (HS) lesions.

PURPOSE

To establish whether there is correlation among different methods of measuring HS lesions, and to investigate the correlation between glenoid bone loss and the various HS lesion measurements and to assess the inter-observer reliability of such measurements.

MATERIAL AND METHODS

We assessed computed tomography (CT) or arthro-CT scans taken from individuals with recurrent anterior glenohumeral dislocation. The scans were independently assessed by two examiners. The parameters assessed were as follows: HS lesion width and depth on the axial and coronal planes, articular arc loss on the axial plane, and percentage of glenoid bone loss on the sagittal plane.

RESULTS

Scans from 50 shoulders were assessed. The percentage of articular arc loss and HS lesion width on the axial plane were the only measurements that exhibited strong correlation (r = 0.83; P < 0.001). The values of the correlation coefficient corresponding to HS lesion depth on the coronal plane were the lowest. Most of the measurements exhibited moderate correlation. The inter-examiner reliability was good relative to all measurements except for HS lesion width and depth on the coronal plane, for which it was moderate.

CONCLUSION

The measurements of articular arc loss and HS lesion width on the axial plane exhibited strong correlation. The inter-examiner reliability relative to articular arc loss, HS lesion width and depth on the axial plane, and glenoid bone loss was good.

The J-Shaped Bone Graft for Anatomic Glenoid Reconstruction: A 10-Year Clinical Follow-up and Computed Tomography-Osteoabsorptiometry Study

BACKGROUND

The J-shaped bone graft procedure is one of the recommended methods to reconstruct significant glenoid rim defects.

PURPOSE

To evaluate long-term (minimum 10-year) clinical outcomes and show further details of the remodeling effects on the articular cavity of the glenoid after J-shaped bone grafting.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 14 patients treated with a J-shaped bone graft procedure were observed clinically. Additionally, bilateral preoperative and postoperative follow-up computed tomography (CT) scans were used for CT-osteoabsorptiometry (OAM) to evaluate the bony remodeling processes.

RESULTS

The follow-up rate was 93% at a mean follow-up time of 10.7 years (range, 10.08-11.75 years). Patients exhibited a mean Constant score of 92.5 (range, 80-100) on the clinical evaluation. All patients had free range of motion and were pain free without any recurrence of instability. Based on CT-OAM, comparable and almost anatomically reconstructed, bilaterally equal glenoid cavities were found postoperatively. The distribution patterns of glenoid subchondral mineralization were bilaterally equal in 85.7% of the patients.

CONCLUSION

The surgical treatment of recurrent shoulder instability with a significant bony Bankart lesion using the J-shaped bone graft procedure provided excellent long-term results. This study lends evidence to support the capability of the J-shaped bone graft procedure to restore the normal glenoid shape due to physiological remodeling processes.

Arthroscopic treatment of glenoid bone loss

Recurrent anterior instability of the glenohumeral joint has long been an arduous problem to solve surgically, owing to its difficulty to the need to restore both osseous and dynamic constraints in the unstable shoulder. Biomechanical studies have indicated that glenoid bone loss shortens the safe arc through which the glenoid can resist axial forces; in these cases, a soft tissue repair alone may be insufficient to maintain stability. Clinical studies have confirmed that major bone loss is associated with an unfavourable outcome. The benefits of using arthroscopic procedures for surgical stabilization of the shoulder include smaller incisions and less soft tissue dissection, better access for repair and, potentially, the maximum respect for the undamaged anatomical structures. The biggest disadvantage of arthroscopic procedures until recently was the inability to successfully treat a significant bone defect. Over the last 10 years, several new arthroscopic techniques have been developed, providing new surgical options for successfully treating soft tissues and bony lesions in anterior-inferior glenohumeral instability. Level of evidence V.

The effect of defect orientation and size on glenohumeral instability: a biomechanical analysis

PURPOSE

The purpose of this study was to determine the relationship between bony stability and percentage of anterior glenoid bone loss and the effect of bone loss orientation.

METHODS

Twelve cadaveric shoulders were studied. Glenoid bone defects were simulated in two different osteotomy angles: 0° and 45° to the superoinferior (SI) axis of the glenoid. The force and displacement required for dislocation were measured under two compressive forces of 40 and 60N. Testing was performed for the intact glenoid and glenoid defects of 2, 4, 6, 8, and 10 mm from the anterior margin.

RESULTS

The maximum force for dislocation with the 2-mm glenoid defect was significantly decreased compared with intact glenoid (p = 0.01), and this force also significantly decreased with each increase in defect size (p < 0.05). The dislocation force for 45° osteotomy was significantly higher than that for 0° osteotomy for all defect widths up to 8 mm with 40N compression and 6 mm with 60N compression (p < 0.001). The displacement at dislocation did not significantly decrease until the 8-mm defect with the 45° osteotomy but significantly decreased with the 4-mm defect with the 0° osteotomy. The required force for dislocation with 60N compression was significantly higher than that with 40N compression for all osteotomy sizes and orientations.

CONCLUSIONS

The decrease in stability even with glenoid bone loss as small as 2 mm or 7.5 % of the glenoid width suggests that bony restoration is recommended whenever any bone loss exists. Bone defects parallel to SI axis may be more susceptible to recurrent instability, and shoulder muscle strengthening exercises may increase glenohumeral compressive force and thus improve glenohumeral stability. Bony restoration is recommended whenever bone loss exists even with small bone fragments particularly those in line with the superior-inferior axis of the glenoid.

Analysis of Agreement Between Computed Tomography Measurements of Glenoid Bone Defects in Anterior Shoulder Instability With and Without Comparison With the Contralateral Shoulder

BACKGROUND

Computed tomography (CT) is frequently used to diagnose glenoid bone defects in anterior shoulder instability. The assessment of glenoid defects on 2-dimensional (2D) and 3-dimensional (3D) CT scans has been reported with and without a comparative study of the contralateral shoulder; however, no previous studies have analyzed if these 4 methods agree.

PURPOSE

To estimate agreement between CT assessments of glenoid defects by examination of the affected shoulder alone and by comparison with the contralateral side on both 2D and 3D CT scans.

STUDY DESIGN

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

METHODS

A total of 200 prospectively enlisted patients affected by unilateral anterior shoulder instability underwent CT of both shoulders. The area of the missing glenoid was calculated on 4 sets of CT scans (2D and 3D CT images with and without comparison with the contralateral shoulder) by using the circle method. Agreement between the 4 measurements in quantifying the bone defect was estimated according to the Bland-Altman method. Agreement between the 4 measurements in assessing the presence and type of defect (fracture or erosion) was analyzed with κ statistics.

RESULTS

Analysis of agreement between CT measurements in quantifying glenoid bone defects showed that the mean difference between the 4 measures was less than 1% of the area of the inferior glenoid in each pairwise comparison. Limits of agreement were always below the established acceptable limit of 5%. The assessment of the presence and type of bone defect showed strong to near-complete agreement between the 4 measurement methods.

CONCLUSION

CT assessments of glenoid bone defects with and without comparison with the contralateral shoulder showed very good agreement in identifying the size, presence, and type of defect in patients with anterior shoulder instability on both 2D and 3D CT scans.

Estimating Glenoid Width for Instability-Related Bone Loss: A CT Evaluation of an MRI Formula

BACKGROUND

Determining the magnitude of glenoid bone loss in cases of shoulder instability is an important step in selecting the optimal reconstructive procedure. Recently, a formula has been proposed that estimates native glenoid width based on magnetic resonance imaging (MRI) measurements of height (1/3 × glenoid height + 15 mm). This technique, however, has not been validated for use with computed tomography (CT), which is often the preferred imaging modality to assess bone deficiencies.

PURPOSE

The purpose of this project was 2-fold: (1) to determine if the MRI-based formula that predicts glenoid width from height is valid with CT and (2) to determine if a more accurate regression can be resolved for use specifically with CT data.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ninety normal shoulder CT scans with preserved osseous anatomy were drawn from an existing database and analyzed. Measurements of glenoid height and width were performed by 2 observers on reconstructed 3-dimensional models. After assessment of reliability, the data were correlated, and regression models were created for male and female shoulders. The accuracy of the MRI-based model's predictions was then compared with that of the CT-based models.

RESULTS

Intra- and interrater reliabilities were good to excellent for height and width, with intraclass correlation coefficients of 0.765 to 0.992. The height and width values had a strong correlation of 0.900 (P < .001). Regression analyses for male and female shoulders produced CT-specific formulas: for men, glenoid width = 2/3 × glenoid height + 5 mm; for women, glenoid width = 2/3 × glenoid height + 3 mm. Comparison of predictions from the MRI- and CT-specific formulas demonstrated good agreement (intraclass correlation coefficient = 0.818). The CT-specific formulas produced a root mean squared error of 1.2 mm, whereas application of the MRI-specific formula to CT images resulted in a root mean squared error of 1.5 mm.

CONCLUSION

Use of the MRI-based formula on CT scans to predict glenoid width produced estimates that were nearly as accurate as the CT-specific formulas. The CT-specific formulas, however, are more accurate at predicting native glenoid width when applied to CT data.

CLINICAL RELEVANCE

Imaging-specific (CT and MRI) formulas have been developed to estimate glenoid bone loss in patients with instability. The CT-specific formula can accurately predict native glenoid width, having an error of only 2.2% of average glenoid width.