MRI can assess glenoid bone loss after shoulder luxation: inter- and intra-individual comparison with CT

Current Concepts in the Measurement of Glenohumeral Bone Loss

PURPOSE

The extent of glenohumeral bone loss seen in anterior shoulder dislocations plays a major role in guiding surgical management of these patients. The need for accurate and reliable preoperative assessment of bone loss on imaging studies is therefore of paramount importance to orthopedic surgeons. This article will focus on the tools that are available to clinicians for quantifying glenoid bone loss with a focus on emerging trends and research in order to describe current practices.

RECENT FINDINGS

Recent evidence supports the use of 3D CT as the most optimal method for quantifying bone loss on the glenoid and humerus. New trends in the use of 3D and ZTE MRI represent exciting alternatives to CT imaging, although they are not widely used and require further investigation. Contemporary thinking surrounding the glenoid track concept and the symbiotic relationship between glenoid and humeral bone loss on shoulder stability has transformed our understanding of these lesions and has inspired a new focus of study for radiologists and orthopedist alike. Although a number of different advanced imaging modalities are utilized to detect and quantify glenohumeral bone loss in practice, the current literature supports 3D CT imaging to provide the most reliable and accurate assessments. The emergence of the glenoid track concept for glenoid and humeral head bone loss has inspired a new area of study for researchers that presents exciting opportunities for the development of a deeper understanding of glenohumeral instability in the future. Ultimately, however, the heterogeneity of literature, which speaks to the diverse practices that exist across the world, limits any firm conclusions from being drawn.

Glenoid bone loss in anterior shoulder dislocation: a multicentric study to assess the most reliable imaging method

PURPOSE

The aim of this multicentric study was to assess which imaging method has the best inter-reader agreement for glenoid bone loss quantification in anterior shoulder instability. A further aim was to calculate the inter-method agreement comparing bilateral CT with unilateral CT and MR arthrography (MRA) with CT measurements. Finally, calculations were carried out to find the least time-consuming method.

METHOD

A retrospective evaluation was performed by 9 readers (or pairs of readers) on a consecutive series of 110 patients with MRA and bilateral shoulder CT. Each reader was asked to calculate the glenoid bone loss of all patients using the following methods: best fit circle area on both MRA and CT images, maximum transverse glenoid width on MRA and CT, CT PICO technique, ratio of the maximum glenoid width to height on MRA and CT, and length of flattening of the anterior glenoid curvature on MRA and CT. Using Pearson's correlation coefficient (PCC), the following agreement values were calculated: the inter-reader for each method, the inter-method for MRA with CT quantifications and the inter-method for CT best-fit circle area and CT PICO. Statistical analysis was carried out to compare the time employed by the readers for each method.

RESULTS

Inter-reader agreement PCC mean values were the following: 0.70 for MRA and 0.77 for CT using best fit circle diameter, 0.68 for MRA and 0.72 for CT using best fit circle area, 0.75 for CT PICO, 0.64 for MRA and 0.62 for CT anterior straight line and 0.49 for MRA and 0.43 for CT using length-to-width ratio. CT-MRA inter-modality PCC mean values were 0.9 for best fit circle diameter, 0.9 for best fit circle area, 0.62 for anterior straight line and 0.94 for length-to-width methods. PCC mean value comparing unilateral CT with PICO CT methods was 0.8. MRA best fit circle area method was significantly faster than the same method performed on CT (p = 0.031), while no significant difference was seen between CT and MRA for remaining measurements.

CONCLUSIONS

CT PICO is the most reliable imaging method, but both CT and MRA can be reliably used to assess glenoid bone loss. Best fit circle area CT and MRA methods are valuable alternative measurement techniques.

Bankart Repair With or Without Concomitant Remplissage Results in Similar Shoulder Motion and Postoperative Outcomes in the Treatment of Shoulder Instability

Purpose

To compare the results of patients who underwent Bankart repair with or without concomitant remplissage for treatment of shoulder instability.

Methods

All patients who underwent shoulder stabilization for shoulder instability from 2014 to 2019 were evaluated. Patients who underwent remplissage were matched to those patients who received no remplissage based on sex, age, body mass index, and date of surgery. Glenoid bone loss and presence of an engaging Hill-Sachs lesion were quantified by 2 independent investigators. Postoperative complications, recurrent instability, revision, shoulder range of motion (ROM), return to sport (RTS), and patient-reported outcome measures (Oxford Shoulder Instability, Single Assessment Numeric Evaluation, and American Shoulder and Elbow Surgeons scores) were compared between groups.

Results

Overall, 31 patients who underwent remplissage were identified and matched to 31 patients who received no remplissage at a mean follow-up of 2.8 ± 1.8 years. Glenoid bone loss was similar between groups (11% vs 11%, P = .956); however, engaging Hill-Sachs lesions were more prevalent in the patients who underwent remplissage than the patients who received no remplissage (84% vs 3%, P < .001). There were no significant differences in rates of redislocation (remplissage: 12.9% vs no remplissage: 9.7%), subjective instability (45.2% vs 25.8%), reoperation (12.9% vs 0%), or revision (12.9% vs 0%) between groups (all P > .05). Also, there were no differences in RTS rates, shoulder range of motion, or patient-reported outcome measures (all P > .05).

Conclusions

If a patient is indicated for Bankart repair with concomitant remplissage, surgeons may expect shoulder motion and postoperative outcomes similar to those of patients without engaging Hill-Sachs lesions who undergo Bankart repair without concomitant remplissage.

Level of Evidence

Therapeutic case series, level IV.

Increased rates of subjective shoulder instability after Bankart repair with remplissage compared to Latarjet surgery

HYPOTHESIS AND BACKGROUND

Controversy exists as to the ideal management of young active patients with subcritical glenoid bone loss and an off-track Hill-Sachs lesion, and the Latarjet and arthroscopic Bankart with remplissage are effective surgical options. The purpose of this study was to compare rates of recurrent instability and reoperation, as well as patient-reported outcome measures, between Latarjet and arthroscopic Bankart repair with remplissage surgery patients. The authors hypothesized that there would be no difference in rates of recurrent instability, reoperation, and postoperative outcomes between patients who underwent Latarjet surgery and patients who underwent Bankart repair with concomitant remplissage postoperatively.

MATERIALS AND METHODS

All patients who underwent primary shoulder stabilization for shoulder instability from 2014 to 2019 were screened. Latarjet and Bankart repair with remplissage patients were included if arthroscopic surgery was performed in response to anterior shoulder instability. Recurrent instability, revision, shoulder range of motion, return to sport (RTS), and patient-reported outcome measures (Oxford Shoulder Instability, Single Assessment Numeric Evaluation, and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form scores) were compared between groups.

RESULTS

Overall, 43 Latarjet patients (age: 29.8 ± 12.1 years, 36 males 7 females) and 28 Bankart repair with remplissage patients (age: 28.2 ± 8.8 years, 25 males 3 females) were included with a mean follow-up of 3.3 ± 1.9 years. Patients who underwent Latarjet surgery had larger amounts of bone loss (19% vs. 11%, P < .001), a lower rate of off-track Hill-Sachs lesions (47% vs. 82%, P < .001), and more frequently had a history of chronic shoulder dislocations (88% vs. 43%, P < .001) compared to Bankart repair with remplissage patients. Latarjet patients less frequently reported feeling subjective shoulder instability after surgery (21% vs. 50%, P = .022), which was defined as feeling apprehension or experiencing a shoulder subluxation or dislocation event. There were no differences in rates of postoperative dislocation, revision, reoperation, or RTS, as well as patient-reported outcome scores, between groups (all P > .05).

CONCLUSION

Despite differences in osseous defects, Latarjet and Bankart repair with remplissage patients had similar rates of clinical, patient-reported, and RTS outcomes at a mean of 3.3 years postoperatively. Latarjet surgery patients may be less likely to experience subjective shoulder instability postoperatively than patients who undergo Bankart repair with concomitant remplissage.

Successful Outcomes and Return to Sport After Arthroscopic Bankart Repair in National Collegiate Athletic Association and National Football League Football Players

OBJECTIVE

To characterize recurrent instability, return to sport (RTS), and patient-reported outcomes (PROs) after arthroscopic Bankart repair for acute traumatic anterior shoulder instability in National Collegiate Athletic Association (NCAA) and National Football League (NFL) football players.

DESIGN

Case series.

SETTING

Orthopaedic and sports medicine clinic.

PARTICIPANTS

National Collegiate Athletic Association and NFL football athletes with traumatic anterior shoulder instability who underwent arthroscopic shoulder stabilization at a single institution with at least 2-year follow-up.

INTERVENTIONS OR ASSESSMENT OF RISK FACTORS OR INDEPENDENT VARIABLES

Arthroscopic Bankart repair.

MAIN OUTCOME MEASURES

Recurrent instability, RTS, patient satisfaction, the visual analog scale (VAS) for pain, American Shoulder and Elbow Surgeons (ASES) score, and Rowe score.

RESULTS

Thirty-three players were included with a mean age of 23.8 years (range, 18-33 years) and a mean follow-up of 6.3 years (range, 4.1-9.3 years). One shoulder (3.0%) had a postoperative subluxation event, and 1 shoulder (3.0%) required revision surgery for issues other than instability; 93.3% of players were able to RTS at the same level or higher for at least 1 season. Mean satisfaction was 8.9 ± 2.3. Mean VAS was 1.0 ± 1.7, and mean ASES and Rowe scores were 90.7 ± 18.5 and 89.7 ± 15.2, respectively.

CONCLUSION

Arthroscopic Bankart repair is an effective surgical intervention for traumatic anterior shoulder instability in NCAA and NFL football players. At a mean 6-year follow-up, surgery restored stability in 97% of cases and 93.3% returned to their preinjury level of sport.

The relationship of glenoid version and severity of glenoid bone loss in anterior shoulder instability patients: A retrospective cohort study

Background/objective

The effect of glenoid version on the severity of glenoid bone loss is not completely understood, although the variation of glenoid version angles is considered to reflect the degree of glenoid bone loss in anterior shoulder instability cases. The objective of this retrospective case-control study is to determine the relationship of the glenoid version and the severity of glenoid bone loss in a group of previously documented recurrent anterior shoulder dislocation patients.

Methods

We retrospectively collected magnetic resonance arthrogram (MRA) data from 72 patients with unidirectional recurrent anterior shoulder instability. The best-fit circle method was used to identify the percentage of glenoid bone loss. Measurements of glenoid labral, chondral, and bony versions were performed using the Friedman method.

Results

Using univariate regression analysis, it was found that a retroversion angle of more than 4 degrees was associated with an increased risk ratio for the occurrence of a critical glenoid defect by approximately 5 times.

Conclusions

24 Univariate logistic regression analysis, used to determine the presence of a critical glenoid bone defect, showed that both the bony version angle and the number of previous dislocations were significantly associated with the extent of glenoid bone loss. A retroversion angle of more than 4 degrees was associated with an approximately five-fold increase in the odds ratio for the presence of a critical glenoid defect. Surgeons may use the value of the measured glenoid version in prediction the required version of the reconstructive treatment.

Magnetic Resonance Imaging Versus Computed Tomography for Three-Dimensional Bone Imaging of Musculoskeletal Pathologies: A Review

Magnetic resonance imaging (MRI) is increasingly utilized as a radiation‐free alternative to computed tomography (CT) for the diagnosis and treatment planning of musculoskeletal pathologies. MR imaging of hard tissues such as cortical bone remains challenging due to their low proton density and short transverse relaxation times, rendering bone tissues as nonspecific low signal structures on MR images obtained from most sequences. Developments in MR image acquisition and post‐processing have opened the path for enhanced MR‐based bone visualization aiming to provide a CT‐like contrast and, as such, ease clinical interpretation. The purpose of this review is to provide an overview of studies comparing MR and CT imaging for diagnostic and treatment planning purposes in orthopedic care, with a special focus on selective bone visualization, bone segmentation, and three‐dimensional (3D) modeling. This review discusses conventional gradient‐echo derived techniques as well as dedicated short echo time acquisition techniques and post‐processing techniques, including the generation of synthetic CT, in the context of 3D and specific bone visualization. Based on the reviewed literature, it may be concluded that the recent developments in MRI‐based bone visualization are promising. MRI alone provides valuable information on both bone and soft tissues for a broad range of applications including diagnostics, 3D modeling, and treatment planning in multiple anatomical regions, including the skull, spine, shoulder, pelvis, and long bones.

Can magnetic resonance imaging accurately and reliably measure humeral cortical thickness?

Background

Historically, imaging osseous detail in three dimensions required a computed tomography (CT) scan with ionizing radiation that poorly visualizes the soft tissues. The purpose of this study was to determine the accuracy and reliability of ultrashort echo time (UTE) magnetic resonance imaging (MRI) in measuring humeral cortical thickness and cancellous density as compared with CT.

Methods

This was a comparative radiographic study in nine cadavers, each of which underwent CT and UTE MRI. On images aligned to the center of the humeral shaft, anterior, posterior, medial, and lateral humeral cortical thickness was measured 5, 10, and 15 cm distal to the top of the head. Cancellous density was measured as signal within a 1-cm diameter region of interest in the center of the head, the subtuberosity head, the subarticular head, and the subarticular glenoid vault. Glenoid cortical thickness was measured at the center of the glenoid. Cortical measurements were compared using mean differences and 95% confidence intervals, paired Student’s t-tests, and intraclass correlation coefficients (ICCs). We compared cancellous measurements using Pearson’s correlation coefficients. For all measurements, we calculated interobserver and intraobserver reliability using ICCs with 0.75 as the lower limit for acceptability.

Results

With regard to accuracy, for humeral cortical thickness measurements, there were no significant differences between MRI and CT measures, and ICCs were >0.75. The glenoid cortical thickness ICC was <0.75. There was no significant correlation between the cancellous signal on MRI and on CT in any region. For both MRI and CT, interobserver reliability and intraobserver reliability were acceptable (ie, >0.75) for almost all humeral cortical thickness measures.

Conclusion

UTE MRI can reliably and accurately measure humeral cortical thickness, but cannot accurately measure cancellous density or accurately and reliably measure glenoid cortical thickness.

The Bony Bankart: Clinical and Technical Considerations

Fractures of the anteroinferior aspect of the glenoid rim, known as a bony Bankart lesions, can occur frequently in the setting of traumatic anterior shoulder dislocation. If these lesions are large and are left untreated in active patients, then recurrent glenohumeral instability due to glenoid bone deficiency may occur. Therefore, the clinician must recognize these lesions when they occur and provide appropriate treatment to restore physiological joint stability. This article aims to provide an overview focusing on clinical and technical considerations in the diagnosis and treatment of bony Bankart lesions.

Glenoid Bone Loss in Shoulder Instability: Superiority of Three-Dimensional Computed Tomography over Two-Dimensional Magnetic Resonance Imaging Using Established Methodology

Backgroud

Recent literature suggests that three-dimensional magnetic resonance imaging (3D MRI) can replace 3D computed tomography (3D CT) when evaluating glenoid bone loss in patients with shoulder instability. We aimed to examine if 2D MRI in conjunction with a validated predictive formula for assessment of glenoid height is equivalent to the gold standard 3D CT scans for patients with recurrent glenohumeral instability.

Methods

Patients with recurrent shoulder instability and available imaging were retrospectively reviewed. Glenoid height on 3D CT and 2D MRI was measured by two blinded raters. Difference and equivalence testing were performed using a paired t-test and two one-sided tests, respectively. The interclass correlation coefficient (ICC) was used to test for interrater reliability, and percent agreement between the measurements of one reviewer was used to assess intrarater reliability.

Results

Using an equivalence margin of 1 mm, 3D CT and 2D MRI were found to be different (p = 0.123). The mean glenoid height was significantly different when measured on 2D MRI (39.09 ± 2.93 mm) compared to 3D CT (38.71 ± 2.89 mm) (p = 0.032). The mean glenoid width was significantly different between 3D CT (30.13 ± 2.43 mm) and 2D MRI (27.45 ± 1.72 mm) (p < 0.001). The 3D CT measurements had better interrater agreement (ICC, 0.91) than 2D MRI measurements (ICC, 0.8). intrarater agreement was also higher on CT.

Conclusions

Measurements of glenoid height using 3D CT and 2D MRI with subsequent calculation of the glenoid width using a validated methodology were not equivalent, and 3D CT was superior. Based on the validated methods for the measurement of glenoid bone loss on advanced imaging studies, 3D CT study must be preferred over 2D MRI in order to estimate the amount of glenoid bone loss in candidates for shoulder stabilization surgery and to assist in surgical decision-making.

Double-loaded suture anchors in the treatment of anteroinferior glenohumeral instability

Hypothesis

The purpose of this study was to determine the clinical outcomes of arthroscopic labral repair for anteroinferior glenohumeral instability with the use of double-loaded suture anchors.

Methods

This study evaluated a series of consecutive patients treated after the senior author changed from single- to double-loaded suture anchors for the treatment of anteroinferior glenohumeral instability with a minimum follow-up period of 2 years. We collected the following outcomes at final follow-up: visual analog scale pain score, Simple Shoulder Test score, American Shoulder and Elbow Surgeons score, and instability recurrence data.

Results

A total of 41 consecutive patients underwent arthroscopic labral repair with double-loaded anchors, of whom 30 (71%) were able to be contacted at a minimum of 2 years postoperatively. These patients included 4 contact or collision athletes (13%). The patients had an average of 12 ± 13 prior dislocations over an average period of 56 ± 57 months preoperatively. Mean glenoid bone loss measured 16% ± 10%, and 67% (18 of 27 patients) had glenoid bone loss ≥ 13.5%. Intraoperatively, 3.2 ± 0.4 anchors were used. No posterior repairs or remplissage procedures were performed. At an average of 6.7 ± 2.7 years' follow-up, the visual analog scale pain score was 0.8 ± 1.4; Simple Shoulder Test score, 11 ± 2; and American Shoulder and Elbow Surgeons score, 90 ± 14. Patients with bone loss < 13.5% had a 0% redislocation rate and 11% subluxation rate, whereas those with bone loss ≥ 13.5% had a 6% reoperation rate, 22% redislocation rate, and 22% subluxation rate.

Conclusion

Arthroscopic labral repair with double-loaded anchors provides satisfactory clinical results at early to mid-term outcome assessment when glenoid bone loss is <13.5%.

Accuracy of Currently Available Methods in Quantifying Anterior Glenoid Bone Loss: Controversy Regarding Gold Standard-A Systematic Review

PURPOSE

To determine the accuracy of glenoid bone loss-measuring methods and assess the influence of the imaging modality on the accuracy of the measurement methods.

METHODS

A literature search was performed in the PubMed (MEDLINE), Embase, and Cochrane databases from 1994 to June 11, 2019. The guidelines and algorithm of the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) were used. Included for analysis were articles reporting the accuracy of glenoid bone loss-measuring methods in patients with anterior shoulder instability by comparing an index test and a reference test. Furthermore, articles were included if anterior glenoid bone loss was quantified using a ruler during arthroscopy or by measurements on plain radiograph(s), computed tomography (CT) images, or magnetic resonance images in living humans. The risk of bias was determined using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.

RESULTS

Twenty-one studies were included, showing 17 different methods. Three studies reported on the accuracy of methods performed on 3-dimensional CT. Two studies determined the accuracy of glenoid bone loss-measuring methods performed on radiography by comparing them with methods performed on 3-dimensional CT. Six studies determined the accuracy of methods performed using imaging modalities with an arthroscopic method as the reference. Eight studies reported on the influence of the imaging modality on the accuracy of the methods. There was no consensus regarding the gold standard. Because of the heterogeneity of the data, a quantitative analysis was not feasible.

CONCLUSIONS

Consensus regarding the gold standard in measuring glenoid bone loss is lacking. The use of heterogeneous data and varying methods contributes to differences in the gold standard, and accuracy therefore cannot be determined.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II, III, and IV studies.

Does Bone Loss Imaging Modality, Measurement Methodology, and Interobserver Reliability Alter Treatment in Glenohumeral Instability?

PURPOSE

To determine, in the context of measuring bone loss in shoulder instability, whether measurement differences between magnetic resonance imaging (MRI) and computed tomography (CT), linear-based and area-based methods, and observers altered the proposed treatment when a standardized algorithm was applied.

METHODS

This was a retrospective, comparative imaging study of preoperative patients with anterior shoulder instability with both an MRI and CT scan within 1 year of one another. On parasagittal images reoriented en face to the glenoid, 2 attending orthopaedic surgeons measured glenoid width, glenoid area, glenoid defect width, and glenoid defect area. On axial images maximal Hill-Sachs width was measured. From these, linear percent glenoid bone loss (%GBL) and area %GBL were calculated, and on-versus off-track was determined. With these results, a recommended treatment was determined by applying a standardized algorithm, in which the Latarjet procedure was selected for %GBL >20%, arthroscopic labral repair and remplissage for off-track lesions with %GBL <20%, and arthroscopic labral repair on-track shoulders with %GBL <20%.

RESULTS

In total, 53 patients with mean ± standard deviation 45 ± 83 days between scans were include with a CT linear %GBL of 23.5 ± 9.6% (range 0%-47%). CT lead to larger measurements of %GBL than MRI (linear P = .008, area P = .003), and fewer shoulders being considered on-track (33.0% vs 40.5%), which would alter treatment in 25% to 34%. Linear measurements produced larger values for %GBL (CT, P < .001; MRI, P < .001), which would alter treatment in 25%. For %GBL, inter-rater reliability was good, with intraclass correlation coefficients varying from 0.727 to 0.832 and Kappa varying from 0.57 to 0.62, but these inter-rater differences would alter treatment in 31%.

CONCLUSIONS

The significant differences in bone loss measurement between imaging modality, measurement method, and observers may lead to differences in treatment in up to 34% of cases. Linear CT measurements resulted in the most aggressive treatment recommendations.

LEVEL OF EVIDENCE

Retrospective Comparative Study: Diagnostic, Level III.

Imaging Quantification of Glenoid Bone Loss in Patients With Glenohumeral Instability: A Systematic Review

To listen to the podcast associated with this article, please select one of the following: iTunes, Google Play, or direct download. OBJECTIVE. The purpose of this study is to determine the most accurate imaging techniques to measure glenoid bone loss in anterior glenohumeral instability through a systematic review of existing literature. MATERIALS AND METHODS. We performed a comprehensive literature search of five databases for original research measuring glenoid bone loss at radiography, CT, or MRI, using prospective or retrospective cohort, case-control, or cadaveric study designs up to January 2018. The Quality Assessment of Diagnostic Accuracy Studies-2 tool aided qualitative assessment of the methods. Data extraction included results, index test interobserver agreement, and accuracy analysis. RESULTS. Twenty-seven studies (evaluating 1425 shoulders) met inclusion criteria after full-text review by two independent readers. Glenoid bone loss was assessed, comparing several index tests to nonimaging (n = 18 studies) and imaging (n = 11) reference standards. Compared with arthroscopic or cadaveric measurements, 2D CT was accurate in six of seven studies (86%), 3D CT was accurate in eight of 10 studies (80%), 2D MRI was accurate in five of seven studies (71%), 3D MRI was accurate in four of four studies (100%), and radiographs were accurate in zero of four studies (0%). Best-fit circle methods (glenoid width or Pico surface area) were the most common and both were accurate (86-90% and 75-100%, respectively) using CT and MRI. Studies had good external validity (78%). Most risk for bias arose from patient selection and reference standards. Only two studies reported sensitivity and specificity, both comparing CT to arthroscopy using different bone loss thresholds (20% and 25%). CONCLUSION. CT and MRI (2D or 3D) accurately measure glenoid bone loss in anterior shoulder instability, but radiographs do not. Best-fit circle measurement techniques are reliable and accurate. Current literature about glenoid bone loss is heterogeneous, and future studies should focus on diagnosis of clinically relevant glenoid bone loss.

ACR Appropriateness Criteria® Shoulder Pain-Traumatic

Traumatic shoulder pain is pain directly attributed to a traumatic event, either acute or chronic. This pain may be the result of either fracture (the clavicle, scapula, or proximal humerus) or soft-tissue injury (most commonly of the rotator cuff, acromioclavicular ligaments, or labroligamentous complex). Imaging assessment of traumatic shoulder pain begins with conventional radiography and, depending on physical examination findings, will require MRI or MR arthrography for assessment of soft-tissue injuries and CT for delineation of fracture planes. Ultrasound excels in assessment of rotator cuff injuries but has limited usefulness for assessment of the deep soft-tissues. CT angiography and conventional arteriography are helpful for assessment of vascular injury, and bone scintigraphy can be used in assessment of complex regional pain syndrome after traumatic shoulder injury. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Does creating a trough on the anterior glenoid rim make a difference in Arthroscopic Bankart repair using suture anchors? A mid-term follow-up retrospective study

PURPOSE

Creating a trough on the anterior glenoid rim is one of the methods used for arthroscopic Bankart repair with suture anchors. The purpose of this study was to analyze clinical and radiological outcomes of arthroscopic Bankart repair with suture anchors; to compare between the outcomes of surgical procedures with and without trough.

METHODS

Clinical and radiological outcomes were evaluated for 116 patients who underwent arthroscopic Bankart repair at our institute from 2005 to 2011. The mean follow-up was 5.2 years (range, 2-8.8 years). All data were divided into trough group (n = 62) and non-trough group (n = 71). Clinical and functional outcomes were assessed pre- and postoperatively as range of motion (ROM), pain on the visual analog scale (p-VAS), function on the visual analog scale (f-VAS), and Rowe score. Radiological outcomes were also evaluated.

RESULTS

The overall postoperative clinical and functional outcomes improved significantly (P < .001). A total of 8 patients (6.8%) showed recurrent instability. Radiologic findings showed mild arthritis in 27 cases (23.1%), moderate arthritis in 6 cases (5.1%), and no severe arthritis. 32 patients showed anterior apprehension after surgery, and 22 out of those 32 patients were from non-trough group. However, no significant difference between the trough and non-trough groups was found with respect to clinical and functional outcomes (P > .05).

CONCLUSION

The additional procedure of creating a trough did not improve clinical outcomes in terms of frank dislocation; however, at the final follow-up, patients with the trough showed less anterior apprehension. Overall, arthroscopic Bankart repair using suture anchors had relatively good clinical outcome, with a redislocation rate of 6.8%.

LEVEL OF EVIDENCE

Level III, Case series.

Feasibility of using an inversion-recovery ultrashort echo time (UTE) sequence for quantification of glenoid bone loss

OBJECTIVE

To utilize the 3D inversion recovery prepared ultrashort echo time with cones readout (IR-UTE-Cones) MRI technique for direct imaging of lamellar bone with comparison to the gold standard of computed tomography (CT).

MATERIALS AND METHODS

CT and MRI was performed on 11 shoulder specimens and three patients. Five specimens had imaging performed before and after glenoid fracture (osteotomy). 2D and 3D volume-rendered CT images were reconstructed and conventional T1-weighted and 3D IR-UTE-Cones MRI techniques were performed. Glenoid widths and defects were independently measured by two readers using the circle method. Measurements were compared with those made from 3D CT datasets. Paired-sample Student's t tests and intraclass correlation coefficients were performed. In addition, 2D CT and 3D IR-UTE-Cones MRI datasets were linearly registered, digitally overlaid, and compared in consensus by these two readers.

RESULTS

Compared with the reference standard (3D CT), glenoid bone diameter measurements made on 2D CT and 3D IR-UTE-Cones were not significantly different for either reader, whereas T1-weighted images underestimated the diameter (mean difference of 0.18 cm, p = 0.003 and 0.16 cm, p = 0.022 for readers 1 and 2, respectively). However, mean margin of error for measuring glenoid bone loss was small for all modalities (range, 1.46-3.92%). All measured ICCs were near perfect. Digitally registered 2D CT and 3D IR-UTE-Cones MRI datasets yielded essentially perfect congruity between the two modalities.

CONCLUSIONS

The 3D IR-UTE-Cones MRI technique selectively visualizes lamellar bone, produces similar contrast to 2D CT imaging, and compares favorably to measurements made using 2D and 3D CT.

Estimation of anterior glenoid bone loss area using the ratio of bone defect length to the distance from posterior glenoid rim to the centre of the glenoid

PURPOSE

Estimation of anterior glenoid bone loss is important for surgical decision-making. The purpose of this study was to describe a method for estimating anterior glenoid bone loss.

METHODS

Thirty-nine cadaveric glenoids were digitized to obtain glenoid geometry. Glenoid bare spot centre, arthroscopic centre, and centre of the inferior glenoid circle relative to the geometric centre were measured. To simulate anterior glenoid bone loss, imaginary sequential osteotomies were created 0°, 22.5°, and 45° to the superior-inferior line in a 3D digitizing programme. Per cent of anterior glenoid bone loss area was calculated as the percentage of defect area relative to the entire area of the glenoid. The relationship between area loss and ratio of bone defect length to the distance from posterior glenoid to various centres was determined.

RESULTS

As the ratio of bone defect length to the distance from posterior glenoid to all three centres increased, the per cent area of bone loss increased exponentially. The ratio using the inferior circle centre and arthroscopic centre was highly correlated to the actual glenoid bone loss in all osteotomies (R ² > 0.90). The ratio using the centre of bare area had the lowest correlation. The ratio of defect length to distance from posterior glenoid to arthroscopic centre greater than 2.4 for 0° and 2.0 for 45° osteotomies results in bone loss area greater than 25 %. The bare area centre had the largest variation. Average bone loss was overestimated when the centre of bare spot was used compared to other centre locations.

CONCLUSION

Per cent of anterior glenoid bone loss can be estimated using the ratio of bone defect length to the distance from posterior glenoid rim to the centre of inferior glenoid circle or arthroscopic centre either preoperatively using 3D CT or arthroscopically which can be useful for determining surgical treatment.

Can glenoid wear be accurately assessed using x-ray imaging? Evaluating agreement of x-ray and magnetic resonance imaging (MRI) Walch classification

BACKGROUND

The Walch classification is the most recognized means of assessing glenoid wear in preoperative planning for shoulder arthroplasty. This classification relies on advanced imaging, which is more expensive and less practical than plain radiographs. The purpose of this study was to determine whether the Walch classification could be accurately applied to x-ray images compared with magnetic resonance imaging (MRI) as the gold standard. We hypothesized that x-ray images cannot adequately replace advanced imaging in the evaluation of glenoid wear.

METHODS

Preoperative axillary x-ray images and MRI scans of 50 patients assessed for shoulder arthroplasty were independently reviewed by 5 raters. Glenoid wear was individually classified according to the Walch classification using each imaging modality. The raters then collectively reviewed the MRI scans and assigned a consensus classification to serve as the gold standard. The κ coefficient was used to determine interobserver agreement for x-ray images and independent MRI reads, as well as the agreement between x-ray images and consensus MRI.

RESULTS

The inter-rater agreement for x-ray images and MRIs was "moderate" (κ = 0.42 and κ = 0.47, respectively) for the 5-category Walch classification (A1, A2, B1, B2, C) and "moderate" (κ = 0.54 and κ = 0.59, respectively) for the 3-category Walch classification (A, B, C). The agreement between x-ray images and consensus MRI was much lower: "fair-to-moderate" (κ = 0.21-0.51) for the 5-category and "moderate" (κ = 0.36-0.60) for the 3-category Walch classification.

DISCUSSION

The inter-rater agreement between x-ray images and consensus MRI is "fair-to-moderate." This is lower than the previously reported reliability of the Walch classification using computed tomography scans. Accordingly, x-ray images are inferior to advanced imaging when assessing glenoid wear.

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.

Three-Dimensional Magnetic Resonance Imaging Quantification of Glenoid Bone Loss Is Equivalent to 3-Dimensional Computed Tomography Quantification: Cadaveric Study

PURPOSE

To assess the ability of 3-dimensional (3D) magnetic resonance imaging (MRI, 1.5 and 3 tesla [T]) to quantify glenoid bone loss in a cadaveric model compared with the current gold standard, 3D computed tomography (CT).

METHODS

Six cadaveric shoulders were used to create a bone loss model, leaving the surrounding soft tissues intact. The anteroposterior (AP) dimension of the glenoid was measured at the glenoid equator and after soft tissue layer closure the specimen underwent scanning (CT, 1.5-T MRI, and 3-T MRI) with the following methods (0%, 10%, and 25% defect by area). Raw axial data from the scans were segmented using manual mask manipulation for bone and reconstructed using Mimics software to obtain a 3D en face glenoid view. Using calibrated Digital Imaging and Communications in Medicine images, the diameter of the glenoid at the equator and the area of the glenoid defect was measured on all imaging modalities.

RESULTS

In specimens with 10% or 25% defects, no difference was detected between imaging modalities when comparing the measured defect size (10% defect P = .27, 25% defect P = .73). All 3 modalities demonstrated a strong correlation with the actual defect size (CT, ρ = .97; 1.5-T MRI, ρ = .93; 3-T MRI, ρ = .92, P < .0001). When looking at the absolute difference between the actual and measured defect area, no significance was noted between imaging modalities (10% defect P = .34, 25% defect P = .47). The error of 3-T 3D MRI increased with increasing defect size (P = .02).

CONCLUSIONS

Both 1.5- and 3-T-based 3D MRI reconstructions of glenoid bone loss correlate with measurements from 3D CT scan data and actual defect size in a cadaveric model. Regardless of imaging modality, the error in bone loss measurement tends to increase with increased defect size. Use of 3D MRI in the setting of shoulder instability could obviate the need for CT scans.

CLINICAL RELEVANCE

The goal of our work was to develop a reproducible method of determining glenoid bone loss from 3D MRI data and hence eliminate the need for CT scans in this setting. This will lead to decreased cost of care as well as decreased radiation exposure to patients. The long-term goal is a fully automated system that is as approachable for clinicians as current 3D CT technology.

Outcomes After Arthroscopic Bankart Repair in Adolescent Athletes Participating in Collision and Contact Sports

Background:

Literature on arthroscopic stabilization in adolescent patients participating in collision and contact sports is limited, as most studies include adolescents within a larger sample group comprised primarily of adults.

Purpose:

To review the outcomes of arthroscopic Bankart repair for anterior shoulder instability in an adolescent population participating in collision and contact sports.

Study Design:

Case series; Level of evidence, 4.

Methods:

This retrospective review included 39 shoulders in 37 adolescent (≤19 years) athletes who underwent primary arthroscopic Bankart repair using suture anchors with at least 2-year follow-up. All patients had a history of trauma to their shoulder resulting in an anterior dislocation. Outcome measures included patient satisfaction, the visual analog scale (VAS) for pain, American Shoulder and Elbow Surgeons (ASES) score, and Rowe score. Recurrence of dislocation and return to sporting activity were also assessed.

Results:

The mean age at the time of surgery was 16.9 years (range, 15-19 years), and the mean follow-up was 6.3 years (range, 4.3-10.0 years); 58.6% of patients participated in collision sports. Time to surgery after the initial dislocation episode was 9.2 months (range, 0.5-36.2 months). Four shoulders (10.3%) had dislocation events postoperatively. The majority (78.1%) of patients returned to sports at the same level of competition. Mean VAS was 0.49 ± 1.0, and the mean ASES and Rowe scores were 92.8 ± 12.6 and 85.0 ± 24.2, respectively. Univariate analyses demonstrated that subjective functional outcomes were negatively correlated with recurrence (ASES, P = .005; Rowe, P = .001) and failure to return to sport (ASES, P = .016; Rowe, P = .004). Independent variables shown to have no significant relationship to functional outcomes included age, follow-up, number of preoperative dislocations, time to surgery, sport classification, competition level, tear extent, number of anchors, concurrent Hill-Sachs lesion, and repair of a superior labral anterior-posterior (SLAP) lesion.

Conclusion:

Arthroscopic Bankart repair is an effective surgical option for traumatic shoulder instability in adolescents participating in collision and contact sports. At a minimum 4-year follow-up, arthroscopic Bankart repair effectively restored stability in 90% of cases; 80% returned to their preinjury level of sport.

Comparison of Intra-articular Findings and Clinical Features Between Patients With Symptomatic Anterior Instability After Recurrent Shoulder Subluxation and Dislocation

PURPOSE

The purpose of this study was to compare the prevalence of concomitant intra-articular pathologies and clinical manifestations after arthroscopic stabilization between patients with symptomatic anterior instabilities following recurrent shoulder subluxations and dislocations.

METHODS

Among patients who underwent arthroscopic stabilization, 28 patients who experienced shoulder subluxations (subluxation group, 26.7 ± 1.8 years) and 84 who had shoulder dislocations (dislocation group, 25.9 ± 2.2 years) were included. Recurrent shoulder subluxation was defined as instability caused by repeated injuries without a history of frank dislocation or manual reduction maneuver. Common inclusion criteria were positive clinical test of anterior instability and Bankart lesion with less than 25% of glenoid bone loss. The pathoanatomies in radiologic and arthroscopic examinations and postoperative clinical outcomes were compared.

RESULTS

The number of instability events was significantly fewer in the subluxation group (5.0 ± 1.3) than in the dislocation group (12.1 ± 2.0; P = .01). The pathologic findings in preoperative radiology demonstrated no intergroup differences, except for the prevalence of Hill-Sachs lesions. In the subluxation group, the Hill-Sachs lesions were significantly less commonly detected with computed tomography and magnetic resonance arthrography (28.6%) than in the dislocation group (63.1%, 60.7%; P = .001, P = .003, respectively). There were no significant differences in arthroscopic findings in both groups including superior labral anterior to posterior lesion (subluxation group, 39.3%; dislocation group, 45.2%), anterior labral periosteal sleeve avulsion lesion (21.4%, 29.8%), and bony Bankart lesion (21.4%, 28.6%). Preoperative and postoperative functional outcomes also did not differ between the groups. There was no statistical difference in terms of the rate of revision or postoperative subjective instability.

CONCLUSIONS

Patients who had anterior instability after recurrent shoulder subluxation demonstrated a similar rate of concomitant intra-articular pathologies requiring the same level of management as recurrent shoulder dislocation. Recurrent shoulder subluxation also displayed similar functional outcomes and failure rate after arthroscopic stabilization procedures as recurrent dislocation. Thus, the clinical importance of symptomatic recurrent subluxation should be considered comparable with that of recurrent dislocation.

LEVEL OF EVIDENCE

Level IV, case control study.

Mean Glenoid Defect Size and Location Associated With Anterior Shoulder Instability: A Systematic Review

BACKGROUND

There is a strong correlation between glenoid defect size and recurrent anterior shoulder instability. A better understanding of glenoid defects could lead to improved treatments and outcomes.

PURPOSE

To (1) determine the rate of reporting numeric measurements for glenoid defect size, (2) determine the consistency of glenoid defect size and location reported within the literature, (3) define the typical size and location of glenoid defects, and (4) determine whether a correlation exists between defect size and treatment outcome.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

PubMed, Ovid, and Cochrane databases were searched for clinical studies measuring glenoid defect size or location. We excluded studies with defect size requirements or pathology other than anterior instability and studies that included patients with known prior surgery. Our search produced 83 studies; 38 studies provided numeric measurements for glenoid defect size and 2 for defect location.

RESULTS

From 1981 to 2000, a total of 5.6% (1 of 18) of the studies reported numeric measurements for glenoid defect size; from 2001 to 2014, the rate of reporting glenoid defects increased to 58.7% (37 of 63). Fourteen studies (n = 1363 shoulders) reported defect size ranges for percentage loss of glenoid width, and 9 studies (n = 570 shoulders) reported defect size ranges for percentage loss of glenoid surface area. According to 2 studies, the mean glenoid defect orientation was pointing toward the 3:01 and 3:20 positions on the glenoid clock face.

CONCLUSION

Since 2001, the rate of reporting numeric measurements for glenoid defect size was only 58.7%. Among studies reporting the percentage loss of glenoid width, 23.6% of shoulders had a defect between 10% and 25%, and among studies reporting the percentage loss of glenoid surface area, 44.7% of shoulders had a defect between 5% and 20%. There is significant variability in the way glenoid bone loss is measured, calculated, and reported.

Diagnosis of Engaging Bipolar Bone Defects in the Shoulder Using 2-Dimensional Computed Tomography: A Cadaveric Study

BACKGROUND

Anatomic studies have demonstrated that bipolar glenoid and humeral bone loss have a cumulative effect on shoulder instability and that these defects may engage in functional positions depending on their size and location, potentially resulting in failure of stabilization procedures. Determining which lesions pose a risk for engagement remains challenging, with arthroscopic assessments and a 3-dimensional computed tomography (CT)-based glenoid track method being accepted approaches at this time.

PURPOSE

The purpose was to investigate the interaction of humeral and glenoid bone defects on shoulder engagement in a cadaveric model. Two alternative approaches to predicting engagement were evaluated: (1) CT of the shoulder in abduction and external rotation (ABER) and (2) measurement of the glenoid lesion width and measurement of a novel parameter, the intact anterior articular angle (IAAA), on conventional 2-dimensional multiplane reformats.

STUDY DESIGN

Controlled laboratory study.

METHODS

Hill-Sachs and glenoid defects of varying sizes were created in 12 cadaveric upper limbs, producing 45 bipolar defect combinations. The defect characteristics were assessed using CT with the shoulder in a neutral position. ABER CT was performed with the shoulder positioned in 60° of glenohumeral abduction (corresponding to 90° of abduction relative to the trunk) and 90° of external rotation. The IAAA was measured as the cartilage arc angle anterior to the Hill-Sachs defect on the axial slice bisecting the humeral head. The performance of the ABER CT and IAAA approaches to predicting engagement were compared with the glenoid track method.

RESULTS

Of the 45 defect combinations, 24 (53%) were classified as engaging using the glenoid track method. ABER CT predicted engagement accurately in 43 of 45 (96%), with a sensitivity and specificity of 92% and 100%, respectively. A logistic model based on the glenoid defect width and IAAA provided a prediction accuracy of 87%, with a sensitivity and specificity of 92% and 81%, respectively.

CONCLUSION/CLINICAL RELEVANCE

Bipolar lesions at risk for engagement can be identified accurately using an ABER CT scan or by performing 2-dimensional measurements of the glenoid defect width and IAAA on conventional CT multiplane reformats. This information will be useful for surgical planning in the setting of bipolar bone defects before shoulder stabilization.

Radiographic sclerotic contour loss in the identification of glenoid bone loss

PURPOSE

Quantification of glenoid bone loss guides surgical management in the setting of anterior shoulder instability. Glenoid defects resulting in ≥20 % articular area loss require bony reconstruction. The objective of this study was to evaluate the utility of sclerotic glenoid contour loss on true anteroposterior radiography in the detection of varying quantities of simulated glenoid bone loss using a cadaveric model.

METHODS

Eight cadaveric scapulae with full radiographic sclerotic contour were osteotomized to produce glenoid surface area reductions of 10-50 %. Radiography was performed initially and following each osteotomy, and assessed by an orthopedic surgeon and radiologist twice. Quantity of glenoid loss was compared using Fisher's exact test. Sensitivity, specificity, and reliability analyses were performed.

RESULTS

On the first radiographic review, sclerotic contour loss was detected in 6 out of 8 scapulae with 50 % area loss, but only 1 out of 8 scapulae with 20 % area loss. There was a significantly higher proportion of radiographs containing sclerotic contour loss for defects with 50 % area loss compared to those with 0-25 % loss (p ≤ 0.02). In the detection of ≥20 % area loss, sclerotic contour loss had a sensitivity of 33-43 % and specificity of 88-100 %. Moderate inter-observer reliability (Cohen's kappa value of 0.42-0.53) and intra-observer reliability (kappa value of 0.46-0.58) were found.

CONCLUSION

Radiographic sclerotic contour loss is commonly observed in radiographs of scapulae with 40-50 % glenoid area loss and less often with smaller lesions. However, this finding lacks utility in discerning specific quantifications of glenoid bone loss. In a clinical setting, sclerotic contour loss suggests the presence of a large glenoid defect that may require bony reconstruction. However, an intact sclerotic contour does not rule out significant bone loss.

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.

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.

Techniques to evaluate glenoid bone loss

Assessing glenoid morphology as well as quantifying bone loss is critical when treating patients with recurrent anterior glenohumeral instability because this greatly affects surgeons surgical planning. Although many surgeons agree that 3-dimensionally reconstructed computed tomography (3DCT) images with humeral head digitally subtracted has been considered to be a gold standard when assessing glenoid morphology, there are some surgeons who are making an attempt to replace computed tomography with magnetic resonance imaging to reduce cost for imaging studies and avoid possible radiation exposure, and demonstrated that MRI was equally valuable as 3DCT to quantify glenoid bone loss. However, the role of preoperative imaging study is not only quantifying glenoid bone loss but to assess the glenoid shape and morphology to facilitate surgeons stabilizing the shoulder. In this view, 3DCT is the most recommended preoperative imaging study for bony tissue which provides critical and substantial information of the glenoid.