Measurement of the Glenoid Track In Vivo as Investigated by 3-Dimensional Motion Analysis Using Open MRI

Arthroscopic remplissage: history, indications, and clinical outcomes

Several surgical procedures have been proposed to address anterior glenohumeral instability, which is one of the most common complaints in the general population. The remplissage, first described in early 2000s, is a procedure performed simultaneously with the arthroscopic Bankart repair to correct large, engaging Hill-Sachs lesions (HSLs). This procedure stabilizes the joint by tenodesing the infraspinatus tendon into the HSL to fill and disengage the defect. This procedure gained popularity because it has relatively low risk and is able to improve shoulder stability while being less invasive than other bone-blocking procedures. The remplissage has become a valuable add-on technique that can substantially improve outcomes in unstable patients undergoing arthroscopic Bankart repair. Nevertheless, several studies in the literature have raised concerns regarding its efficacy in critically unstable patients and the potential range of motion limitations that can arise postoperatively. Additional comparative studies and trials should be conducted to appropriately establish the role of remplissage in treating anterior instability, especially in patients with critical bone loss.

Glenoid track revisited

The risk of Hill-Sachs lesion (HSL) to cause instability depends not only on the HSL but also on the glenoid size. Clinically, the only method to assess the risk of instability considering the dynamic interaction of both, the HSL together with the glenoid bone loss, is the glenoid track concept. Since it was introduced in a cadaveric study, its clinical efficacy and validity have been reported in the literature. Sometimes, the medial margin of the footprint (lateral margin of the glenoid track) is difficult to identify when a HSL is overriding the footprint. In such cases, we propose a method to draw an imaginary line connecting 2 landmarks. Although 3-dimensional computed tomography is the most accurate and widely used method to assess on/off-track lesions, our interest gradually is shifting toward magnetic resonance imaging (MRI), which has no radiation concern. The current magnetic resonance method is still under way. There are various risk factors influencing the recurrent instability after surgery. The glenoid track concept deals with only 1 of these factors, that is, instability caused by bony lesions. Therefore, the following 2 issues are important: 1) how to assess the glenoid track precisely and 2) how to incorporate other risk factors into consideration. The former can be achieved by obtaining the custom-made glenoid track width using not the fixed value of 83%, but more individualized value obtained by measuring the active horizontal extension angle of the opposite shoulder in the sitting position. At the same time, the gray zone (peripheral-track lesion) needs to be clearly defined. The latter can be achieved by incorporating the risk factors other than the bony lesions. One example is the Glenoid Track Instability Management Score (GTIMS), a combination of the glenoid track concept and the instability severity index score. This new scoring system is expected to increase the predictive potential of the scoring system, and accordingly to enhance clinical decision-making.

Glenoid track and subcritical Hill-Sachs lesion

Background

We have proposed the concept of glenoid track ("on-track/off-track" lesion) to evaluate the risk of engagement of the Hill-Sachs lesion with the glenoid after arthroscopic Bankart repair. This concept has been widely used and many clinical validation studies have been reported. To measure the glenoid track width, we have recommended to use 3-dimensional computed tomography (CT) images. However, the CT method has the issue of radiation exposure and involves time and effort to make 3-dimensional CT images from 2-dimensional images. For these reasons, there are several reports describing the measurement method using magnetic resonance imaging. Recently, the threshold of the critical glenoid bone loss becomes lower. A zone of bone loss below the critical size is called "subcritical bone loss", which might be related to deterioration of quality of life and bone grafting is recommended. We applied the concept of "subcritical bone loss" to the glenoid track. Patients with "on-track" lesions can be divided into 2 subgroups: those with a "peripheral-track" lesion (most medial 1/4) and those with a "central-track" lesion (the rest 3/4). More recently, similar evaluation methods to evaluate the risk of "off-track" lesions have been reported: ''distance to dislocation'' and "Hill-Sachs interval/glenoid track ratio". Also, similar concept to "peripheral-track" lesion, "near-track" lesion was reported. The concept of "peripheral-track" lesion is a concept of assessing an "on-track" lesion which is very close to the medial margin of the glenoid track (subcritical bone loss).

Methods

Similar evaluation methods to evaluate the risk of "off-track" or "peripheral-track" lesions were proposed in the literature. A review was performed by searching PubMed. Journal articles published between January 2014 and January 2023 were taken into account. They were compared and their differences were explained.

Results

The "near-track" lesion concept is similar to "peripheral-track" lesion. However, the cutoff value is different: Hill-Sachs occupancy ≥ 75% is the "peripheral-track" lesion, whereas "distance to dislocation" < 8 mm is the "near-track" lesion.

Conclusion

We introduced update of the glenoid track concept including the evaluation method, peripheral-track lesion, and its clinical application.

The glenoid track concept is insufficient to predict Bankart failures: a computed tomography scan study

Background

The glenoid track concept identifies patients with "off-track" (engaging) Hill-Sachs lesions (HSLs) as poor candidates for arthroscopic Bankart repair (ABR) due to the high risk of shoulder instability recurrence.

Purpose

To retrospectively calculate the glenoid track index, using preoperative computed tomography (CT) scans, in a cohort of patients with failed ABR. We hypothesized that all patients with a failed ABR would have engaging ("off-track") HSLs on preoperative CT scan.

Type of Study

CT scan study.

Methods

Preoperative CT scan of 45 patients, seen in our facility for failed ABR, was used to retrospectively calculate the glenoid track index. The risk of recurrence was also calculated for each patient using Instability Severity Index Score (ISI-Score) and Glenoid Track Instability Management Score (GTIMS). There were 37 failed isolated ABRs and 8 associated HS remplissage. The mean t age at surgery was 24 years (range, 15-52) and instability recurred at a mean of 29 months postoperative (range, 3-167).

Results

Preoperative CT scan imaging identified "off-track" bony lesions in 85% of patients (38/45) and "on-track" lesions in 15% (7/45). No significant differences were noted between the 2 groups (off-track vs. on-track) regarding patient age, hyperlaxity, sports participation, size of HS lesion, or ISI-Score. The mean glenoid bone loss was 15.7% (range, 4-36%) with mean HS width was greater than 20 mm in 66% of CT scans. The preoperative ISI-Score was predictive of failures (>3 points in all patients) with no difference between on-track and off-track patients (6.3 ± 1.7 vs. 6.6 ± 1.7, P = .453). By contrast, the GTIMS did not predict failures as there was a significant difference between GTIMS for on-track and off-track patients (2.1 ± 1.3 vs. 6.6 ± 1.7).

Conclusions

The glenoid track concept alone is insufficient to predict Bankart failures: in the present series of failed ABR, 15% of shoulders had "on-track" (non-engaging) lesions on preoperative CT scan. In patients, with "on-track" bony lesions, the ISI-Score is a useful predictive tool to detect patients at risk of failure, while the GTIMS is not.

Validating the Glenoid Track Concept Using Dynamic Arthroscopic Assessment

Background

Failure after isolated Bankart repair has led surgeons to consider when to address the Hill-Sachs lesion, which is thought to be a contributor to recurrent instability. One approach utilizes the glenoid track concept to determine whether a Hill-Sachs lesion is classified as "off-track," suggesting that the addition of a remplissage procedure may aid stability. However, the accuracy and reliability of using this approach require validation using an appropriate reference.

Purpose

To determine the accuracy and reliability of using the glenoid track concept against dynamic arthroscopic assessment of Hill-Sachs lesion engagement.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

A total of 49 patients undergoing arthroscopic Bankart repair surgery for recurrent traumatic anterior shoulder instability were enrolled in this diagnostic validation study. Shoulders were classified as on-track or off-track using 3-dimensional computed tomography (3DCT) and static arthroscopic measurements. These classifications were compared with dynamic arthroscopic assessment (engagement of the Hill-Sachs lesion on the anterior glenoid rim in the 'athletic position') to determine their accuracy and reliability.

Results

The 3DCT-based measurements to determine glenoid track status had a higher positive predictive value (66% vs 42%), higher specificity (47% vs 42%), and higher accuracy (65% vs 59%) compared with static arthroscopic measurements. Static arthroscopic measurements to determine glenoid track status had a higher negative predictive value (96% vs 64%) and higher sensitivity (96% vs 81%) compared with 3DCT-based measurements. Interrater reliability (Krippendorff α) was 'fair' for determining the glenoid track status using 3DCT (0.368; 95% CI, 0.217-0.519) and 'moderate' for static arthroscopic measurements (0.523; 95% CI, 0.364-0.666). Intrarater reliability (intraclass correlation coefficient [ICC] 3,k) was 'moderate' for 3DCT measurements (0.660; 95% CI, 0.444-0.798) and 'good' for static arthroscopic measurements (0.769; 95% CI, 0.629-0.862).

Conclusion

Determining glenoid track status using either 3DCT or static arthroscopic measurements yielded moderate accuracy and reliability. Surgeons using the glenoid track concept to aid surgical decision-making in traumatic recurrent anterior shoulder instability should utilize 3DCT or static arthroscopic measurements with caution.

How does dynamic arthroscopic tracking compare with radiologic glenoid track for identification of on- and off-track lesions in anterior shoulder instability?

BACKGROUND

Current treatment paradigms for anterior shoulder instability are based on radiologic measurements of glenohumeral bone defects, and mathematical calculation of the glenoid track (GT) is used to classify lesions into on-track and off-track morphology. However, radiologic measurements have shown high variability, and GT widths under dynamic conditions have been reported to be significantly smaller than those under static radiologic conditions. The purpose of this study was to assess the reliability, reproducibility, and diagnostic validity of dynamic arthroscopic standardized tracking (DAST) in comparison to the gold-standard radiologic track measurement method for the identification of on- and off-track bony lesions in patients with anteroinferior shoulder instability.

METHODS

Between January 2018 and August 2022, 114 patients with traumatic anterior shoulder instability were evaluated using 3-T magnetic resonance imaging or computed tomography scans; glenoid bone loss, Hill-Sachs interval, GT, and Hill-Sachs occupancy ratio (HSO) were measured, and defects were classified as on-track or off-track defects and peripheral-track defects (based on HSO percentage) by 2 independent researchers. During arthroscopy, a standardized method (DAST method) was used by 2 independent observers to classify defects into on-track defects (central and peripheral) and off-track defects. Interobserver reliability of the DAST and radiologic methods was calculated using the κ statistic and reported as percentage agreement. Diagnostic validity (sensitivity, specificity, positive predictive value, and negative predictive value) of the DAST method was calculated using the radiologic track (HSO percentage) as the gold standard.

RESULTS

The radiologically measured mean glenoid bone loss percentage, Hill-Sachs interval, and HSO in off-track lesions were lower with the arthroscopic method (DAST) as compared with the radiologic method. The DAST method showed nearly perfect agreement between the 2 observers for the on-track/off-track classification (κ = 0.96, P < .001) and the on-track central or peripheral /off-track classification (κ = 0.88, P < .001). The radiologic method showed greater interobserver variability (κ = 0.31 and κ = 0.24, respectively) with only fair agreement for both classifications. Inter-method agreement varied between 71% and 79% (95% confidence interval, 62%-86%) between the 2 observers, and reliability was assessed as slight (κ = 0.16) to fair (κ = 0.38). Overall, for identification of an off-track lesion, the DAST method showed maximum specificity (81% and 78%) when radiologic peripheral-track lesions (HSO percentage of 75%-100%) were considered off-track and showed maximum sensitivity when arthroscopic peripheral-track lesions were classified as off-track.

CONCLUSION

Although inter-method agreement was low, a standardized arthroscopic tracking method (DAST method) showed superior interobserver agreement and reliability for lesion classification in comparison to the radiologic track method. Incorporating DAST into current algorithms may help reduce variability in surgical decision making.

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 Track Assessment at Imaging in Anterior Shoulder Instability: Rationale and Step-by-Step Guide

Anterior shoulder dislocation is the most common form of joint instability in humans, usually resulting in soft-tissue injury to the glenohumeral capsuloligamentous and labral structures. Bipolar bone lesions in the form of fractures of the anterior glenoid rim and posterolateral humeral head are often associated with anterior shoulder dislocation and can be a cause or result of recurrent dislocations. Glenoid track assessment is an evolving concept that incorporates the pathomechanics of anterior shoulder instability into its management. Currently widely endorsed by orthopedic surgeons, this concept has ramifications for prognostication, treatment planning, and outcome assessment of anterior shoulder dislocation. The glenoid track is the contact zone between the humeral head and glenoid during shoulder motion from the neutral position to abduction and external rotation. Two key determinants of on-track or off-track status of a Hill-Sachs lesion (HSL) are the glenoid track width (GTW) and Hill-Sachs interval (HSI). If the GTW is less than the HSI, an HSL is off track. If the GTW is greater than the HSI, an HSL is on track. The authors focus on the rationale behind the glenoid track concept and explain stepwise assessment of the glenoid track at CT or MRI. Off-track to on-track conversion is a primary goal in stabilizing the shoulder with anterior instability. The key role that imaging plays in glenoid track assessment warrants radiologists' recognition of this concept along with its challenges and pitfalls and the production of relevant and actionable radiology reports for orthopedic surgeons-to the ultimate benefit of patients. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

A numerical study of the contact geometry and pressure distribution along the glenoid track

The glenoid track geometry and the contact forces acting on the glenohumeral joint at static positions of 30°, 60°, 90° and 120° of abduction with 90° of external rotation were evaluated using a finite element model of the shoulder that, differently from most usual approximations, accounts the humeral head translations and the deformable-to-deformable non-spherical joint contact. The model was based on data acquired from clinical exams of a single subject, including the proximal humerus, scapula, their respective cartilages concerning the glenohumeral joint, and the rotator cuff and deltoid muscles. The forces acting on the glenohumeral joint were estimated using a simulation framework consisting of an optimization procedure allied with finite element analysis that seeks the minimum muscle forces that stabilize the joint. The joint reaction force magnitude increases up to 680.25 N at 90° of abduction and decreases at further positions. From 60° onward the articular contact remains at the anterior region of the glenoid cartilage and follows an inferior to superior path at the posterior region of the humeral head cartilage. The maximum contact pressure of 3.104 MPa occurs at 90° abduction. Although translating inferiorly throughout the movement, the projection of the humeral head center at the glenoid plane remains at the central region of the glenoid surface. The model results qualitatively matched the trends observed in the literature and supports the consideration of the translational degrees of freedom to evaluate the joint contact mechanics.

Glenoid Track Width Is Smaller Under Dynamic Conditions: An In Vivo Dual-Fluoroscopy Imaging Study

BACKGROUND

The glenoid track concept has been widely used to assess the risk of instability due to bipolar bone loss. The glenoid track width was commonly used as 83% of the glenoid width to determine if a lesion was on-track or off-track. However, the value was obtained under static conditions, and it may not be able to reflect the actual mechanism of traumatic dislocation during motion.

PURPOSE

To compare the glenoid track width under dynamic and static conditions using a dual-fluoroscopic imaging system.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 40 shoulders of 20 healthy volunteers were examined for both dynamic and static tests within a dual-fluoroscopic imaging system at 5 different arm positions: 30°, 60°, 90°, 120°, and 150° of abduction, keeping the shoulder at 90° of external rotation. The participants performed a fast horizontal arm backswing for dynamic tests while keeping their arm in maximum horizontal extension for static tests. Computed tomography scans were used to create 3-dimensional models of the humerus and scapula for 2-dimensional to 3-dimensional image registration. Magnetic resonance imaging scans were obtained to delineate the medial margin of the rotator cuff insertion. The glenoid track width was measured as the distance from the anterior rim of the glenoid to the medial margin of the rotator cuff insertion and compared between static and dynamic conditions.

RESULTS

The mean glenoid track widths at 30°, 60°, 90°, 120°, and 150° of abduction were significantly smaller under dynamic conditions (88%, 81%, 72%, 69%, and 68% of the glenoid width) than those under static conditions (101%, 92%, 84%, 78%, and 77% of the glenoid width) (all P < .001). The glenoid track width significantly decreased with the increasing abduction angles in the range of 30° to 120° under static conditions (all P < .003) and 30° to 90° under dynamic conditions (all P < .001).

CONCLUSION

A smaller dynamic-based value should be considered for the glenoid track width when distinguishing on-track/off-track lesions. Clinical evidence is needed to establish the superiority of the dynamic-based value over the static-based value as an indicator for augmentation procedures.

CLINICAL RELEVANCE

Some off-track lesions might be misclassified as on-track lesions when the original commonly used static-based value of 83% is used as the glenoid track width.

Arthroscopic Remplissage for the Treatment of Anterior Shoulder Instability: Current and Evolving Concepts

➢

A Hill-Sachs lesion (HSL) is a compression fracture on the posterolateral humeral head that can increase the risk of recurrent shoulder instability after isolated arthroscopic Bankart repair.

➢

Remplissage involves capsulotenodesis of the infraspinatus tendon and posterior capsule into the HSL to prevent its engagement with the glenoid rim through extra-articular conversion and restraint against humeral head anterior translation.

➢

The glenoid track concept can be applied preoperatively and intraoperatively to evaluate risk of recurrence and help direct clinical management options for recurrent shoulder instability.

➢

Recent literature supports expanding indications for remplissage to include patients with on-track HSLs who are at increased risk of recurrence including collision athletes, military personal, and patients with joint hyperlaxity.

➢

New techniques and suture constructs have demonstrated improved biomechanical strength while avoiding the need to access the subacromial space.

Comparison of computed tomography and 3D magnetic resonance imaging in evaluating glenohumeral instability bone loss

BACKGROUND

To determine whether the addition of 3-dimensional (3D) magnetic resonance imaging (MRI) to standard MRI sequences is comparable to 3D computed tomographic (CT) scan evaluation of glenoid and humeral bone loss in glenohumeral instability.

METHODS

Eighteen patients who presented with glenohumeral instability were prospectively enrolled and received both MRI and CT within 1 week of each other. The MRI included an additional sequence (volumetric interpolated breath-hold examination [VIBE]) that underwent postprocessing for reformations. The addition of a VIBE protocol, on average, is an additional 4-4.5 minutes in the scanner. CT data also underwent 3D postprocessing, and therefore each patient had 4 imaging modalities (2D CT, 2D MRI, 3D CT reformats, and 3D MRI reformats). Each sequence underwent the following measurements from 2 separate reviewers: glenoid defect, glenoid defect percentage, humeral defect, humeral defect percentage, and evaluation of glenoid track and version. Paired t tests were used to assess differences between imaging modalities and χ² for glenoid track. Intra- and interobserver reliability were evaluated. Bland-Altman tests were also performed to assess the agreement between CT and MRI. In addition, we determined the cost of each imaging modality at our institution.

RESULTS

3D MRI measurements for glenoid and humeral bone loss measurements were comparable to 3D CT (Table 1). There were no significant differences for glenoid defect size and percentage, or humeral defect size and percentage (P > .05) (Table 2). Bland-Altman analysis demonstrated strong agreement, with small measurement errors for 3D CT and 3D MRI percentage glenoid bone loss. There was also no difference in evaluation for determining on vs. off track between any of the imaging modalities. Inter- and intrarater reliability was good to excellent for all CT and MRI measurements (r ≥ 0.7).

CONCLUSION

3D MRI measurements for bone loss in glenohumeral instability through use of VIBE sequence were equivalent to 3D CT. At our institution, undergoing MRI with 3D reconstruction was 1.67 times cheaper than MRI and CT with 3D reconstructions. 3D MRI may be a useful adjuvant to standard MRI sequences to allow concurrent soft tissue and accurate assessment of glenoid and humeral bone loss in glenohumeral instability.

Ultrasonographic Assessment of Glenohumeral Joint Stability Immediately After Arthroscopic Bankart-Bristow Procedure

Background:

The changes in glenohumeral joint stability after surgery in a clinical setting are yet unknown.

Purpose/Hypothesis:

This study aimed to compare the anterior humeral head translation between pre- and postsurgical conditions using ultrasonography. It was hypothesized that ultrasonographic assessment would reveal decreased anterior translation.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 27 patients (24 male, 3 female; mean age, 24.1 ± 9.7 years) with anterior shoulder instability were studied prospectively. All the patients underwent the arthroscopic Bankart-Bristow procedure under general anesthesia, and ultrasonographic evaluation was performed before and immediately after surgery. The forearm was fixed with an arm positioner in the beach-chair position, and the ultrasonographic transducer was located at the posterior part of the shoulder to visualize the humeral head and glenoid rim at the level of interval between the infraspinatus tendon and teres minor tendon. The upper arm was drawn anteriorly with a 40-N force at 0°, 45°, and 90° of shoulder abduction with neutral rotation. The distance from the posterior edge of the glenoid to that of the humeral head was measured using ultrasonography with and without anterior force. Anterior translation was defined by subtracting the distance with anterior force from the distance without anterior force.

Results:

The humeral head position was translated posteriorly immediately after surgery in all patients. Anterior translation decreased significantly after surgery at 45° (7.7 ± 4.3 vs 5.8 ± 2.0 mm; P = .031) and 90° (8.9 ± 3.4 vs 6.1 ± 2.2 mm; P < .001) of abduction, whereas there was no difference between pre- and postsurgical translation at 0° of abduction (4.9 ± 2.3 vs 4.0 ± 2.1 mm, P = .089).

Conclusion:

Ultrasonographic assessment immediately after a Bankart-Bristow procedure showed the humeral head was translated posteriorly relative to the glenoid at 0°, 45°, and 90° of abduction. The surgery also decreased anterior translation in response to an anteriorly directed force at 45° and 90° of abduction.

Ultrasound Assessment of Anterior Humeral Head Translation in Patients With Anterior Shoulder Instability: Correlation With Demographic, Radiographic, and Clinical Data

Background:

Ultrasonography can be used to quantitatively assess anterior humeral head translation (AHHT) at different degrees of shoulder abduction. Risk factors for recurrent shoulder instability have been identified.

Hypothesis:

It was hypothesized that the number of dislocations or glenoid or humeral bone loss would be associated with more AHHT as measured using ultrasound.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 39 patients who underwent surgery for anterior shoulder instability were prospectively studied. Ultrasound assessment of AHHT was performed immediately after general anesthesia was induced. The upper arm was placed at 0°, 45°, and 90° of abduction, and a 40-N anterior force was applied to the proximal third of the arm. The distance from the posterior edge of the glenoid to that of the humeral head was measured at each abduction angle using ultrasound with and without a 40-N anterior force, and the AHHT was calculated. The differences in translation at each shoulder angle were compared. Additionally, the authors investigated the association between AHHT and demographic, radiographic, and clinical data.

Results:

Compared with the AHHT at 0° of abduction (5.29 mm), translation was significantly larger at 45° of abduction (8.90 mm; P < .01) and 90° of abduction (9.46 mm; P < .01). The mean translation was significantly larger in female patients than in male patients at all degrees of abduction (P ≤ .036 for all). There was no correlation between AHHT at any abduction angle and number of dislocations, clinical data, or radiographic data (including bone loss).

Conclusion:

Ultrasound assessment of AHHT showed larger amounts of laxity at 45° and 90° than at 0° of abduction. Anterior glenohumeral laxity was greater in female than male patients. Glenoid or humeral bone loss did not correlate with AHHT, thereby clarifying that bone loss has no direct effect on measurements of capsular laxity in neutral rotation.

Glenoid Bone Loss Directly Affects Hill-Sachs Morphology: An Advanced 3-Dimensional Analysis

BACKGROUND

While the glenoid track concept presents a useful prediction for recurrent glenohumeral instability, little is known about the humeral head bony architecture as it relates to glenoid erosion in the setting of bipolar bone loss.

PURPOSE

To (1) qualitatively and quantitatively analyze the interplay between glenoid bone loss (GBL) and Hill-Sachs lesions (HSLs) in a cohort of patients with anterior instability using 3-dimensional imaging software and (2) assess the relationships between GBL and HSL characteristics.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients were identified who had anterior shoulder instability with a minimum 5% GBL and evidence of HSL confirmed on computed tomography. Unilateral 3-dimensional models of the ipsilateral proximal humeral head and en face sagittal oblique view of the glenoid were reconstructed using MIMICS software (Materialise NV). GBL surface area, width, defect length, and glenoid track width were quantified. The volume, surface area, width, and depth of identified HSLs were quantified with their location (medial, superior, and inferior extent) on the humeral head. Severity of GBL was defined as percentage glenoid bone surface area loss and categorized as low grade (5%-10%), moderate grade (>10% to 20%), high grade (>20% to 30%), and extensive (>30%). Analysis of variance was then computed to determine significance (P < .05) between severity of GBL and associated HSL parameters.

RESULTS

In total, 100 patients met inclusion criteria (mean age, 27.9 years; range, 18-43 years), which included 58 right shoulders and 42 left shoulders (84 male, 16 female). Among groups, there were 32 patients with low-grade GBL (mean GBL = 6.1%), 38 with moderate grade (mean GBL = 16.2%), 17 with high grade (mean GBL = 23.7%), and 13 with extensive (mean GBL = 34.0%), with an overall mean GBL of 18.1% (range, 5%-39%). Patients with 5%-10% GBL had significantly narrower HSLs (average and maximum width; P < .03) and deeper HSLs (average depth; P = .002) as compared with all other GBL groups, while greater GBL was associated with wider and shallower HSLs. GBL width, percentage width loss, defect length, and glenoid track width all significantly differed across the 4 GBL groups (P < .05).

CONCLUSION

HSLs had significantly different morphological characteristics depending on the severity of GBL, indicating that GBL was directly related to the characteristics of HSLs. Patients presenting with smaller glenoid defects had significantly narrower and deeper HSLs with less humeral head surface area loss, while greater GBL was associated with wider and shallower HSLs.

Evaluating Bone Loss in Anterior Shoulder Instability

Anterior shoulder instability is a common orthopaedic condition that often involves damage to the bony architecture of the glenohumeral joint in addition to the capsulolabral complex. Patients with recurrent shoulder dislocations are at increased risk for glenohumeral bone loss, as each instability event leads to the accumulation of additional glenoid and/or humeral head bone defects. Depending on the degree of bone loss, successful treatment may need to address bony lesions in addition to injured soft-tissue structures. As such, a thorough understanding of methods for evaluating bone loss preoperatively, in terms of location, size, and significance, is essential. Although numerous imaging modalities can be used, three-dimensional imaging has proven particularly useful and is now an integral component of preoperative planning.

Does native glenoid anatomy predispose to shoulder instability? An MRI analysis

BACKGROUND

It is unclear if native glenohumeral anatomic features predispose young patients to instability and if such anatomic risk factors differ between males and females. The purpose of this study was to compare glenoid and humeral head dimensions between patients with a documented instability event without bone loss to matched controls and to evaluate for sex-based differences across measurements. The authors hypothesized that a smaller glenoid width and glenoid surface area would be significant risk factors for instability, whereas humeral head width would not.

METHODS

A prospectively maintained database was queried for patients aged <21 years who underwent magnetic resonance imaging (MRI) for shoulder instability. Patients with prior shoulder surgery, bony Bankart, or glenoid or humeral bone loss were excluded. Patients were matched by sex and age to control patients who had no history of shoulder instability. Two blinded independent raters measured glenoid height, glenoid width, and humeral head width on sagittal MRI. Glenoid surface area, glenoid index (ratio of glenoid height to width), and glenohumeral mismatch ratio (ratio of humeral head width to glenoid width) were calculated.

RESULTS

A total of 107 instability patients and 107 controls were included (150 males and 64 females). Among the entire cohort, there were no differences in glenoid height, glenoid width, glenoid surface area, humeral head width, or glenoid index between patients with instability and controls. Overall, those with instability had a greater glenohumeral mismatch ratio (P = .029) compared with controls. When stratified by sex, female controls and instability patients showed no differences in any of the glenoid or humerus dimensions. However, males with instability had a smaller glenoid width by 3.5% (P = .017), smaller glenoid surface area by 5.2% (P = .015), and a greater glenohumeral mismatch ratio (P = .027) compared with controls.

CONCLUSION

Compared with controls, males with instability were found to have smaller glenoid width and surface area, and a glenoid width that was proportionally smaller relative to humeral width. In contrast, bony glenohumeral morphology did not appear to be a significant risk factor for instability among females. These sex-based differences suggest that anatomic factors may influence risk of instability for male and female patients differently.

Dynamic Double-Sling Augmentation Prevents Anteroinferior Translation for Recurrent Anteroinferior Shoulder Dislocation With 20% Glenoid Bone Loss: A Cadaveric Biomechanical Study

PURPOSE

To biomechanically compare the dynamic double-sling with single-sling augmentation using the conjoined tendon (CT) with 20% of an anteroinferior glenoid bone defect under the high loads in shoulders.

METHODS

With the shoulder in 60° of glenohumeral abduction and 60° of external rotation, the 12 shoulders stability was tested sequentially in 5 conditions: intact, 20% glenoid bone loss, Bankart repair, single-sling augmentation with the CT, and double-sling augmentation with both the CT and long head of the biceps tendon (LHBT). The anteroinferior humeral head (HH) translation force of 20N, 30N, 40N, 50N, or 60N was applied to determine the shoulder stability in each condition.

RESULTS

The total HH translation over 8.77 mm represented the anteroinferior shoulder instability (95% confidence interval of bone defect: 7.76-8.77 mm). A significant increase in anteroinferior HH translation was demonstrated after the creation of 20% glenoid bone defect under the 20N translational force (10.52 ± 0.71 mm). Structural failure after the Bankart repair and the single-sling augmentation under the 30N (9.84 ± 1.25 mm) and 40N (9.59 ± 0.66 mm) translational forces, respectively, were observed. The double-sling augmentation effectively prevented the anteroinferior HH translation under the translational force of less than 40N, and only half of the augmentation structure (8.25 ± 1.66 mm) had failed under the 50N translational forces.

CONCLUSION

In the absence of any Hill-Sachs lesion and when tested at 60° abduction and external rotation in shoulders with 20% glenoid bone defects, at time-zero, the double-sling augmentation strategy could effectively prevent anteroinferior translation when compared with the Bankart repair or the single-sling augmentation technique under all magnitudes of the translational force in biomechanical simulation. Nevertheless, none of the constructs restored the HH translation to the normal intact state.

CLINICAL RELEVANCE

Double-sling augmentation technique may represent a reliable option for preventing anteroinferior translation.

Comparing in vivo three-dimensional shoulder elevation kinematics between standing and supine postures

Background

It is often assumed that body posture, standing vs. supine, changes shoulder muscle activation and range of motion, but these altered shoulder mechanics have not been objectively assessed. We expected the supine posture might facilitate scapular rotation and change subacromial pressure. The purpose of this study is to evaluate the influence of body posture on shoulder kinematics during arm elevation.

Methods

Ten males and eight females with a mean age of 33 years participated in this study. Shoulder kinematics were assessed during scapular plane elevation in the standing and supine postures by using single-plane fluoroscopic images. Kinematics were measured using 3-dimensional to 2-dimensional model-image registration techniques: matching the 3-dimensional bone model derived from computed tomography onto each fluoroscopic image. Glenohumeral superior/inferior translation, acromiohumeral distance, and scapular rotations were compared between the postures. The effect of sex also was evaluated.

Results

With the arm at the side position, the humeral head in the supine posture was located 0.5 mm superior compared to the standing posture (P < .001). During humeral elevation, the humeral head significantly shifted more inferiorly in the supine posture than in standing; the biggest mean difference was 0.6 mm, P = .003. But acromiohumeral distance during elevation was not significantly affected by the body posture (P = .05). Scapular upward rotation and posterior tilt were significantly different between the postures (P < .001). Sex had statistically significant, but quantitatively small, effects on shoulder kinematics.

Conclusions

Body postures affect shoulder kinematics during humeral elevation. This knowledge will be useful to optimize rehabilitation exercises and for diagnostic insight.

Limites da artroscopia na instabilidade anterior do ombro

Muito se discute sobre os limites do tratamento da instabilidade anterior do ombro por artroscopia. O avanço no entendimento das repercussões biomecânicas das lesões bipolares sobre a estabilidade do ombro, bem como na identificação de fatores relacionados ao maior risco de recidiva têm nos ajudado a definir, de forma mais apurada, os limites do reparo por via artroscópica.

Ressaltamos a importância de diferenciação entre perda óssea por erosão da glenoide (POAG) e fraturas da borda da glenoide, pois o prognóstico do tratamento diverge entre essas formas de falha óssea da glenoide. Neste contexto, entendemos que há três tipos de falha óssea: a) Bankart ósseo (fratura); b) combinada; e c) POAG, e abordaremos as opções de tratamento sugerido em cada situação.

Até há pouco tempo, a escolha do método cirúrgico era norteada basicamente pelo grau de acometimento ósseo. Com a evolução do conhecimento, da biomecânica das lesões bipolares e do conceito do glenoid track (trilho da glenoide), o ponto de corte da lesão crítica, vem sendo alterado com tendência de queda. Além das falhas ou perdas ósseas, outras variáveis foram adicionadas e tornaram a decisão mais complexa, porém um pouco mais objetiva.

O presente artigo de atualização tem como objetivo fazer uma breve revisão da anatomia com as principais lesões encontradas na instabilidade; abordar detalhes importantes na técnica cirúrgica artroscópica, em especial nos casos complexos, e trazer as evidências atuais sobre os assuntos de maior divergência, buscando guiar o cirurgião na tomada de decisão.

Current concepts in anterior glenohumeral instability: diagnosis and treatment

The glenohumeral joint is the most dislocated articulation, accounting for more than 50% of all joint dislocations. The reason behind shoulder instability should be investigated in detail for successful management, and the treatment plan should be individualized for all patients. Several classification systems have been proposed for glenohumeral instability. A physical exam is mandatory no matter what classification system is used. When treating patients with anterior shoulder instability, surgeons need to be aware of the critical size of the bone loss, which is commonly seen. The glenoid track concept was clinically adopted, and the measurement of the glenoid track for surgical decision-making is recommended. Detailed assessment of existing soft tissue injury to the labrum, capsule, glenohumeral ligaments, and rotator cuff is also mandatory as their presence influences the surgical outcome. Rehabilitation, arthroscopic repair techniques, open Bankart procedure, capsular plication, remplissage, Latarjet technique, iliac crest, and other bone grafts offer the surgeon different treatment options according to the type of patient and the lesions to be treated. Three-dimensional (3D) technologies can help to evaluate glenoid and humeral defects. Patient-specific guides are low-cost surgical instruments and can be used in shoulder instability surgery. 3D printing will undoubtedly become an essential tool to achieve the best results in glenohumeral instability surgery.

Editorial Commentary: Management of First-Time Anterior Shoulder Instability Requires Risk Stratification and Surgery for Many, But Not All

The management of a patient with a first-time anterior shoulder dislocation has been the subject of longstanding debate among shoulder surgeons. A number of prognostic factors for recurrent instability have been proposed, including younger age, male sex, contact sports, and glenoid bone loss. Predictive tools and scores have been developed to assist in risk stratifying this patient population; however, no universally agreed upon, clinically validated algorithm exists. More recently, there has been emerging evidence favoring early surgical stabilization, as it has been shown to result in better overall outcomes compared with patients undergoing surgery following episodes of recurrent instability. With each subsequent dislocation or subluxation event, there is increased glenoid bone loss (and development of inverted-pear glenoid), a greater prevalence of engaging (i.e., off-track) Hill-Sachs lesions, more extensive labral tears, a greater risk of rotator cuff involvement (in the older patient), and increased plastic and/or permanent deformation, elongation, and compromise of the antero-inferior glenohumeral joint capsule and associated inferior glenohumeral ligament complex. Moreover, there is now sufficient evidence to suggest that recurrence comes at a cost, as it is a major risk factor for poor outcomes following arthroscopic stabilization. However, one risk is overtreatment, potentially exposing those individuals who would not have had another instability event due to an unnecessary procedure. We should continue to use the available evidence within the literature to help risk-stratify patients and develop an individualized treatment plan through a shared decision-making process with the patient.

Arthroscopic Versus Open Anterior Shoulder Stabilization: A Prospective Randomized Clinical Trial With 15-Year Follow-up With an Assessment of the Glenoid Being "On-Track" and "Off-Track" as a Predictor of Failure

BACKGROUND

Recent studies have demonstrated equivalent short-term results when comparing arthroscopic versus open anterior shoulder stabilization. However, none have evaluated the long-term clinical outcomes of patients after arthroscopic or open anterior shoulder stabilization, with inclusion of an assessment of preoperative glenoid tracking.

PURPOSE

To compare long-term clinical outcomes of patients with recurrent anterior shoulder instability randomized to open and arthroscopic stabilization groups. Additionally, preoperative magnetic resonance imaging (MRI) studies were used to assess whether the shoulders were "on-track" or "off-track" to ascertain a prediction of increased failure risk.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A consecutive series of 64 patients with recurrent anterior shoulder instability were randomized to receive either arthroscopic or open stabilization by a single surgeon. Follow-up assessments were performed at minimum 15-year follow-up using established postoperative evaluations. Clinical failure was defined as any recurrent dislocation postoperatively or subjective instability. Preoperative MRI scans were obtained to calculate the glenoid track and designate shoulders as on-track or off-track. These results were then correlated with the patients' clinical results at their latest follow-up.

RESULTS

Of 64 patients, 60 (28 arthroscopic and 32 open) were contacted or examined for follow-up (range, 15-17 years). The mean age at the time of surgery was 25 years (range, 19-42 years), while the mean age at the time of this assessment was 40 years (range, 34-57 years). The rates of arthroscopic and open long-term failure were 14.3% (4/28) and 12.5% (4/32), respectively. There were no differences in subjective shoulder outcome scores between the treatment groups. Of the 56 shoulders, with available MRI studies, 8 (14.3%) were determined to be off-track. Of these 8 shoulders, there were 2 surgical failures (25.0%; 1 treated arthroscopically, 1 treated open). In the on-track group, 6 of 48 had failed surgery (12.5%; 3 open, 3 arthroscopic [P = .280]).

CONCLUSION

Long-term clinical outcomes were comparable at 15 years postoperatively between the arthroscopic and open stabilization groups. The presence of an off-track lesion may be associated with a higher rate of recurrent instability in both cohorts at long-term follow-up; however, this study was underpowered to verify this situation.

Editorial Commentary: Personalized Medicine for Shoulder Instability May Result in Best Outcomes With the Lowest Complication Rates

Personalization is a type of medical care in which the treatment is customized for an individual patient. When treating shoulder instability, we need to consider not only soft-tissue damage but also the bony lesion and patient characteristics. Of particular importance is the consideration of whether there is anterior glenoid bone loss, together with the presence of a Hill-Sachs lesion, on or off-track, as well as whether the patient is hyperlax and/or is an athlete, in which case in what type of sport. In hyperlax, nonoverhead sport athletes with recurrent anterior instability and glenoid bone loss <15%, Bankart repair with subscapularis augmentation is an effective procedure with a lower risk of complications and arthritis than a bony procedure. This is a perfect example of personalized medicine indicating a particular treatment to the benefit of patients.

Anterior and posterior glenoid bone augmentation options for shoulder instability: state of the art

Bony lesions are highly prevalent in anterior shoulder instability and can be a significant cause of failure of stabilisation procedures if they are not adequately addressed. The glenoid track concept describes the dynamic interaction between the humeral head and glenoid defects in anterior shoulder instability. It has been beneficial for understanding the role played by bone defects in this entity. As a consequence, the popularity of glenoid augmentation procedures aimed to treat anterior glenoid bone defects; reconstructing the anatomy of the glenohumeral joint has risen sharply in the last decade. Although bone defects are less common in posterior instability, posterior bone block procedures can be indicated to treat not only posterior bony lesions, attritional posterior glenoid erosion or dysplasia but also normal or retroverted glenoids to provide an extended glenoid surface to increase the glenohumeral stability. The purpose of this review was to analyse the rationale, current indications and results of surgical techniques aimed to augment the glenoid surface in patients diagnosed of either anterior or posterior instability by assessing a thorough review of modern literature. Classical techniques such as Latarjet or free bone block procedures have proven to be effective in augmenting the glenoid surface and consequently achieving adequate shoulder stability with good clinical outcomes and early return to athletic activity. Innovations in surgical techniques have permitted to perform these procedures arthroscopically. Arthroscopy provides the theoretical advantages of lower morbidity and faster recovery, as well as the identification and treatment of concomitant pathologies.

Imaging Modalities for the Glenoid Track in Recurrent Shoulder Instability: A Systematic Review

Background:

The glenoid track (GT) concept illustrates how the degree of glenoid bone loss and humeral bone loss in the glenohumeral joint can guide further treatment in a patient with anterior instability. The importance of determining which lesions are at risk for recurrent instability involves imaging of the glenohumeral joint, but no studies have determined which type of imaging is the most appropriate.

Purpose/Hypothesis:

The purpose of this study was to determine the validity and accuracy of different imaging modalities for measuring the GT in shoulders with recurrent anterior instability. We hypothesized that 3-dimensional computed tomography (3D-CT) would be the most accurate imaging technique.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using PubMed, Scopus, Medline, and Cochrane libraries between database inception and July 2019. We included all clinical trials or cadaveric studies that evaluated imaging modalities for assessing the GT.

Results:

A total of 13 studies were included in this review: 1 study using 2-dimensional CT, 6 studies using 3D-CT, 4 studies using magnetic resonance imaging (MRI), 1 study using magnetic resonance arthrography (MRA)/MRI, and 1 study combining CT and MRI. The mean sensitivity, specificity, and accuracy for 2D-CT was 92%, 100%, and 96%, respectively. For MRI, the means were 72.2%, 87.9%, and 84.2%, respectively. No papers included 3D-CT metrics. The mean intraclass correlation coefficients (ICCs) for intraobserver reliability were 0.9046 for 3D-CT and 0.867 for MRI. ICCs for interobserver reliability were 0.8164, 0.8845, and 0.43 for 3D-CT, MRI, and MRA/MRI, respectively.

Conclusion:

There is evidence to support the use of both CT and MRI imaging modalities in assessing the GT. In addition, few studies have compared radiographic measurements with a gold standard, and even fewer have looked at the GT concept as a predictor of outcomes. Thus, future studies are needed to further evaluate which imaging modality is the most accurate to assess the GT.

Failure Rates After Revision Arthroscopic Stabilization for Recurrent Anterior Shoulder Instability Based on Anterior Capsulolabral Complex Conditions

Background:

A labral retear is an important contributing factor to surgical failure after arthroscopic soft tissue stabilization for recurrent anterior shoulder instability. However, surgeons frequently encounter poor tissue conditions in the anterior capsule, such as capsular tears, during revision surgery.

Purpose:

To analyze the clinical outcomes and failure rates of revision arthroscopic stabilization after failed Bankart repair based on the tissue conditions of the anterior capsule and the labrum. Outcomes were compared for revision after failed Bankart repair because of a labral retear versus a healed labrum but with capsular tears.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 55 patients who underwent revision arthroscopic stabilization after failed Bankart repair were included. Revision surgery was indicated if patients had a history of recurrent instability with positive apprehension test results, regardless of magnetic resonance imaging (MRI) findings of a labral retear. Patients were allocated into 2 groups based on arthroscopic findings at the time of revision surgery: group 1 consisted of patients who had a healed labrum with definite anterior capsular tears, and group 2 comprised patients who had labral retears without capsular tears. Clinical outcomes were assessed using the American Shoulder and Elbow Surgeons score, Rowe score, and surgical failure rate.

Results:

Overall, 10 patients were included in group 1, and 45 patients were included in group 2. No capsular tears were detected on preoperative MRI or magnetic resonance arthrography scans in either group, whereas all patients in group 2 had evidence of anterior labral retears on imaging scans. After revision surgery, 9 patients (16.4%) showed surgical failure by 25.6 months postoperatively. Patients in group 1 had a significantly higher surgical failure rate than did those in group 2 (4 patients [40.0%] vs 5 patients [11.1%], respectively; P = .04). The incidence of capsular tears was significantly higher in patients with surgical failure versus those without surgical failure (44.4% vs 13.0%, respectively; P = .04).

Conclusion:

A capsular tear of the anterior capsulolabral complex was an important indicator for surgical failure after revision arthroscopic stabilization. If patients demonstrate symptomatic instability after arthroscopic soft tissue stabilization without evidence of labral retears on imaging scans, an anterior capsular tear should be considered as a possible factor for recurrence.

Evolving Concepts in the Management of Shoulder Instability

BACKGROUND

Shoulder instability exists on a spectrum ranging from subtle subluxation and pain to dislocation and can be the result of a traumatic event or repetitive microtrauma. Shoulder instability can result in significant disability and often requires surgical intervention, especially amongst younger, active patient populations. The optimal treatment of shoulder instability depends on the degree of instability and concomitant pathology involving the labrum, capsule, and bony anatomy of the glenoid and humeral head. Even with surgical intervention, recurrent instability remains a relatively common and difficult problem to address.

PURPOSE

With a focus on anterior instability, the purpose of this review article is to discuss the current assessment and treatment of shoulder instability, and highlight current and future treatment modalities, as well as to identify current trends and deficiencies in our current management. We also provide an algorithm for the surgical treatment of anterior shoulder instability.

METHODS

Literature databases were extensively searched for recent articles related to the mechanism, diagnosis, and treatment of shoulder instability to comprise a comprehensive review.

CONCLUSION

Although there are multiple treatment modalities available for shoulder instability, such as nonoperative management, open and arthroscopic Bankart repair, Latarjet procedures, and remplissage, orthopaedic surgeons continue to learn about the most appropriate method of management as increasing long-term outcomes become available.

Clinical and radiographic outcomes after Latarjet using suture-button fixation

Background

Latarjet has become a common treatment option for patients with shoulder instability in the setting of bone loss. The coracoid is commonly secured with screws

Methods

All patients who underwent Latarjet with suture-button fixation with minimum 1-year follow-up were eligible for inclusion. Preoperative demographic and clinical outcome data including American Shoulder and Elbow Surgeons (ASES), Single Assessment Numerical Evaluation (SANE), and Visual Analog Scale (VAS) were recorded and compared with postoperative scores. Radiographs were reviewed for signs of nonunion. Complications were recorded.

Results

Overall 21 patients (76% male, average age: 30.4 ± 11.3 years) underwent Latarjet with suture-button fixation. Significant improvements at 1 year were seen in ASES (P < 0.001), SANE (P < 0.001), and VAS (P = 0.011) scores compared with preoperative scores. Of the 21 patients who had reached 1-year follow-up, 17 (81%) reached 2-year follow-up. For the 17 patients who reached 2-year follow-up, there were significant improvements in ASES (P = 0.001), SANE (P = 0.001), and VAS (P = 0.005) scores from preoperative values. When isolating the 17 patients with 2-year follow-up, there were no significant differences between their 1-year and 2-year ASES (P = 0.73), SANE (P = 0.17), and VAS (P = 0.37) scores. Overall, 3 patients (14%) sustained a complication (one redislocation, one with coracoid migration and a fibrous union, and one superior labral tear requiring biceps tenodesis and superior labral repair).

Conclusion

Suture-button fixation of the coracoid during the Latarjet provides encouraging clinical and radiographic outcomes at 1 and 2 years.

Does an "Off-Track" Hill-Sachs Lesion That Is Misclassified as "Non-Engaging" Affect Outcomes From Bankart Repair Alone Compared With Bankart Repair Combined With Remplissage?

PURPOSE

To determine how intraoperative assessment (engagement test) may affect recurrent dislocation rate and to compare the clinical outcomes, recurrence rates, and presence of on-/off-track conditions between cases that received arthroscopic Bankart repair alone (nonengaged Hill-Sachs lesion) and Bankart repair with remplissage (engaged Hill-Sachs lesion).

METHODS

We retrospectively reviewed 213 patients who underwent arthroscopic Bankart repair alone (186 patients with nonengaging lesions, group A) or with remplissage (27 patients with engaging lesion, group B) for recurrent anterior shoulder instability with <25% glenoid bone defect. The presence of an engaging Hill-Sachs lesion was determined during arthroscopic evaluation. On-track or off-track lesions were assessed retrospectively from preoperative 3-dimensional (3D) computed tomography (CT).

RESULTS

Mean glenoid bone defect was 13.7% in group A and 20.7% in group B (P < .001). Off-track lesions were identified in 8.1% (15/186) and 100% (27/27) in group B. At the final follow-up (minimum 2 years; mean follow-up periods after surgery of 50.1 months in group A and 47.7 months in group B), there were no significant differences in shoulder functional scores and recurrence rates between groups, despite improvement after surgery. In the off-track lesion (group A-1: nonengaging but off-track lesion), recurrence instability occurred in 9 patients (60%, 9/15). Also, comparing group A-1 and group B, we noted significant differences in shoulder functional scores and recurrence rates (P < .001).

CONCLUSION

Of 186 patients, 8.1% with nonengaging Hill-Sachs lesions during direct arthroscopic examination under anesthesia actually demonstrated off-track lesions on preoperative 3D CT scans retrospectively, with 60% experiencing recurrent instability. Intraoperative manual assessment for Hill-Sachs engagement was inferior to 3D CT scan in establishing the presence of off-track defects.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Determining On-/Off-track Lesions in Glenohumeral Dislocation Using Multiplanar Reconstruction Computed Tomography Is Easier and More Reproducible Than Using 3-dimensional Computed Tomography

BACKGROUND

The glenoid track is a useful tool to predict engagement and therefore the risk of recurrence of dislocation in the presence of Hill-Sachs and/or bony Bankart lesions. To assess the glenoid track preoperatively, only methods using 3-dimensional reconstruction (3DR) have been described, but these lack a standardized, reliable, and easy description.

PURPOSE/HYPOTHESIS

The purpose was to evaluate a new method for determining the glenoid track using computed tomography (CT) scan with multiplanar reconstruction (MPR) in comparison with using 3DR images. Our hypothesis was that the MPR method would be easier to standardize and more reproducible.

STUDY DESIGN

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

METHODS

A total of 52 patients whose arthro-CT scan revealed a Hill-Sachs lesion, whether in combination with a bony Bankart lesion or not, were included. Digital Imaging and Communications in Medicine data from the 52 CT scans were all analyzed using open source image analysis software. Glenoid width, with or without associated bony defect, and the Hill-Sachs interval (HSI) were measured on MPR as well as on 3DR images. All measurements obtained using both methods were directly compared and evaluated for intra- and interobserver reliability.

RESULTS

In absolute values, only small differences were seen between the MPR and 3DR methods, amounting to a maximal difference of 0.07 cm for the HSI and 0.04 cm for the glenoid width. For glenoid measurements, both methods were similar. For humeral measurements, the MPR method demonstrated higher inter- and intraobserver reliability than did the 3DR method.

CONCLUSION

The newly described MPR method for the assessment of the glenoid track and HSI is at least as accurate as the published 3DR method, with better intra- and interobserver reliability. Because MPRs are also easier to obtain, this method could be recommended in daily practice.

Use of a 3D Virtually Reconstructed Patient-Specific Model to Examine the Effect of Acetabular Labral Interference on Hip Range of Motion

Background:

The labrum is likely to influence impingement, which may also depend on acetabular coverage. Simulating impingement using 3-dimensional (3D) computed tomography (CT) is a potential solution to evaluating range of motion (ROM); however, it is based on bony structures rather than on soft tissue.

Purpose:

To examine ROM when the labrum is considered in a 3D dynamic simulation. A particular focus was evaluation of maximum flexion and internal rotation angles before occurrence of impingement, comparing them in cases of cam-type femoroacetabular impingement (FAI) and borderline developmental dysplasia of the hip (BDDH).

Study Design:

Descriptive laboratory study.

Methods:

Magnetic resonance imaging (MRI) and CT scans of 40 hips (20 with cam-type FAI and 20 with BDDH) were reviewed retrospectively. The thickness and width of the labrum were measured on MRI scans. A virtual labrum was reconstructed based on patient-specific sizes measured on MRI scans. The impingement point was identified using 3D dynamic simulation and was compared with the internal rotation angle before and after labral reconstruction.

Results:

The thickness and width of the labrum were significantly larger in BDDH than in FAI (P < .001). In FAI, the maximum internal rotation angles without the labrum were 30.3° at 90° of flexion and 56.9° at 45° of flexion, with these values decreasing to 18.7° and 41.4°, respectively, after labral reconstruction (P < .001). In BDDH, the maximum internal rotation angles were 48.0° at 90° of flexion and 76.7° at 45° of flexion without the labrum, decreasing to 31.1° and 55.3°, respectively, after labral reconstruction (P < .001). The differences in the angles before and after labral reconstruction were larger in BDDH than in FAI (90° of flexion, P = .03; 45° of flexion, P = .01).

Conclusion:

As the labrum was significantly more hypertrophic in BDDH than in FAI, the virtual labral model revealed that the labrum’s interference with the maximum internal rotation angle was also significantly larger in BDDH.

Clinical Relevance:

The labrum has a significant effect on impingement; this is more significant for BDDH than for FAI.

Clinical and radiological examination of bony-mediated shoulder instability

The coexistence of glenoid and humeral head bone defects may increase the risk of recurrence of instability after soft tissue repair.

Revealed factors in medical history such as male gender, younger age of dislocation, an increasing number of dislocations, contact sports, and manual work or epilepsy may increase the recurrence rate of instability.

In physical examination, positive bony apprehension test, catching and crepitations in shoulder movement may suggest osseous deficiency.

Anteroposterior and axial views allow for the detection of particular bony lesions in patients with recurrent anterior shoulder instability.

Computed Tomography (CT) with multiplanar reconstruction (MPR) and various types of 3D rendering in 2D (quasi-3D-CT) and 3D (true-3D-CT) space allows not only detection of glenoid and humeral bone defects but most of all their quantification and relations (engaging/not-engaging and on-track/off-track) in the context of bipolar lesion.

Magnetic resonance imaging (MRI) is increasingly developing and can provide an equally accurate measurement tool for bone assessment, avoiding radiation exposure for the patient.

Cite this article: EFORT Open Rev 2020;5:815-827. DOI: 10.1302/2058-5241.5.200049

Risk Factors for Recurrent Anterior Glenohumeral Instability and Clinical Failure Following Primary Latarjet Procedures: An Analysis of 344 Patients

BACKGROUND

Patients with a greater risk of recurrent instability and inferior clinical outcomes following a primary Latarjet procedure can be preoperatively identified on the basis of clinical, radiographic, and demographic criteria. The purpose of this study was to identify risk factors influencing the rates of recurrent anterior glenohumeral instability and clinical failure following a primary Latarjet procedure.

METHODS

All patients who underwent a primary Latarjet procedure were prospectively enrolled and evaluated. The Western Ontario Shoulder Instability Index (WOSI) and Single Assessment Numeric Evaluation (SANE) outcome scores were collected at a minimum 5-year follow-up along with evidence of recurrent instability. Recurrent instability (recurrent subluxation or dislocation) was considered as a failure. Clinical failure was defined as a postoperative WOSI score of ≥630 points (≤70% normal) or a SANE score of ≤70 points.

RESULTS

From 2004 to 2014, 344 patients (358 shoulders) with a mean age of 30.6 years (range, 16 to 68 years) were enrolled and had a mean follow-up time of 75 months (range, 61 to 89 months). The median postoperative WOSI score was 265 points (range, 0 to 1,100 points), and the median SANE score was 88 points (range, 50 to 100 points). Recurrence occurred in 17 shoulders (4.7%), 5 with dislocation and 12 with subluxation; and 28 (8.2%) of 341 shoulders without recurrent instability were clinical failures following a Latarjet procedure. The risk factors for recurrence included atraumatic dislocation (odds ratio [OR], 4.6; p < 0.01) and bilateral instability (OR, 4.0; p = 0.01), whereas the risk factors for clinical failure (WOSI score of ≥630 points or SANE score of ≤70 points) were female sex (OR, 2.8; p < 0.01) and bilateral instability (OR, 4.6; p = 0.01).

CONCLUSIONS

Outcomes at a mean of >6 years following a primary Latarjet procedure for anterior shoulder instability were very good, with an overall recurrence rate of 4.7%. An additional 8.2% of cases were defined as clinical failures. Patients with an atraumatic mechanism of primary dislocation, bilateral instability, and female sex were identified to be at a greater risk of recurrence or clinical failure. Although additional work is necessary, patients with capsuloligamentous laxity, relatively atraumatic instability history, bilateral instability, and female sex may be preoperatively identified as having a higher risk of treatment failure after a primary Latarjet procedure.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

When to Abandon the Arthroscopic Bankart Repair: A Systematic Review

CONTEXT

Bone loss is a major factor in determining surgical choice in patients with anterior glenohumeral instability. Although bone loss has been described, there is no consensus on glenoid, humeral head, and bipolar bone loss limits for which arthroscopic-only management with Bankart repair can be performed.

OBJECTIVE

To provide guidelines for selecting a more complex repair or reconstruction (in lieu of arthroscopic-only Bankart repair) in the setting of glenohumeral instability based on available literature.

DATA SOURCES

An electronic search of the literature for the period from 2000 to 2019 was performed using PubMed (MEDLINE).

STUDY SELECTION

Studies were included if they quantified bone loss (humeral head or glenoid) in the setting of anterior instability treated with arthroscopic Bankart repair.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Study design, level of evidence, patient demographics, follow-up, recurrence rates, and measures of bone loss (glenoid, humeral head, bipolar).

RESULTS

A total of 14 studies met the inclusion criteria. Of these, 10 measured glenoid bone loss, 5 measured humeral head bone loss, and 2 measured "tracking" without explicit measurement of humeral head bone loss. Measurement techniques for glenoid and humeral head bone loss varied widely. Recommendations for maximum glenoid bone loss for arthroscopic repair were largely <15% of glenoid width in recent studies. Recommendations regarding humeral head loss were more variable (many authors providing only qualitative descriptions) with increasing attention on glenohumeral tracking.

CONCLUSION

It is essential that a standardized method of glenoid and humeral head bone loss measurements be performed preoperatively to assess which patients will have successful stabilization after arthroscopic Bankart repair. Glenoid bone loss should be <15%, and humeral head lesions should be "on track" if an arthroscopic-only Bankart is planned. If there is greater bone loss, adjunct or open procedures should be performed.

Glenoid track evaluation by a validated finite-element shoulder numerical model

BACKGROUND

The limits of the glenoid track have been defined through methods that do not take properly into account the physiological articular forces involved in the articular contact, which may interfere with its size. Finite elements numerical models can simulate joint forces more realistically.

OBJECTIVE

To evaluate the glenoid track in a finite element numerical model of the shoulder.

METHODS

We developed a finite element numerical model of the shoulder, based on imaging exams of a volunteer, including the proximal humerus, scapula, their respective articular cartilages, and the rotator cuff muscles. An algorithm to balance the weight of the arm calculated muscle, wrapping, and articular reaction forces. The model has freedom of translation in three axes. The articular contact characteristics and glenoid track's dimensions according to the literature references were evaluated in 60°, 90° and 120° of abduction, all at the 90° external rotation.

RESULTS

The model's anatomy and physiology were validated. The value of the glenoid track (according to Yamamoto's parameters) was 86% of glenoid length at 90° abduction before loading of forces, and 79% afterwards. The glenoid track at 60°, 90° and 120° of abduction (Omori's parameters) corresponded, respectively, to 71%, 88% and 104% of glenoid length before loading of forces, and 76%, 84% and 103% afterward.

CONCLUSION

The numerical model is suitable for the shoulder articular contact evaluation. The articular contact analysis ratifies the glenoid track concept and contributes to its evolution. This value is influenced by glenohumeral joint forces, which should be considered for the analysis.

LEVEL OF EVIDENCE

Basic Science Study; Computer Modelling.

Effects of Glenoid and Humeral Bone Defects on Recurrent Anterior Instability of the Shoulder

For proper treatment of recurrent anterior instability of the shoulder with a bone defect, the defect size should be assessed preoperatively with three-dimensional computed tomography or magnetic resonance imaging. In general, the risk of postoperative recurrence of instability is estimated on the basis of preoperative imaging of bipolar bone defects: more than 20%–25% glenoid bone loss and off-track Hill-Sachs lesions have been considered risk factors for recurrence. In patients with a glenoid bone defect more than 20%–25%, a bone graft procedure, such as the Latarjet procedure, is preferred regardless of the glenoid track concept, because compared with arthroscopic stabilization procedure, it provides greater postoperative stability. For patients with a borderline glenoid bone defect (around 20%), surgeons should discuss surgical options with the patients, considering their demand and physical activity level. In addition, the surgeon should take care to prevent postoperative instability and long-term complications. Arthroscopic soft-tissue reconstruction including labral repair and capsular plication combined with the additional remplissage procedure is an anatomical procedure and could be considered as one of the primary treatment methods for patients with glenoid bone defects around 20%. Therefore, treatment strategies for recurrent anterior shoulder instability combined with bone defects should be determined more flexibly on the basis of the patient's individual condition.

Editorial Commentary: Methodology of Measuring Bone Loss in Recurrent Shoulder Instability Surgery: Traditional Computed Tomography Scan and Magnetic Resonance Imaging Do Not Tell the Full Story

When measuring bone loss in recurrent shoulder instability, both computed tomography (CT) scan and magnetic resonance imaging (MRI) are accurate using the circle method. However, measurement of on- versus off-track lesions can be inconsistent, and measuring Hill-Sachs lesions on MRI relative to an extrapolated rotator cuff attachment is difficult. In the end, determination of on- versus off-track treatment is quite difficult, and for this determination, differences between CT scan and MRI may be clinically imperceptible. Thus, for now, we, and we believe, other surgeons will continue to stick with the circle technique when determining individual patient treatment for recurrent shoulder instability.

Peripheral-Track and Central-Track Hill-Sachs Lesions: A New Concept of Assessing an On-Track Lesion

BACKGROUND

It has been demonstrated biomechanically that 25% is a critical size defect of the glenoid. However, a recent clinical study reported that a bone loss between 13.5% and 20% (subcritical bone loss) led to impairment of quality of life but not a recurrence of instability.

PURPOSE

To clarify whether a subcritical bone loss exists in assessing a Hill-Sachs lesion via a disease-specific quality of life questionnaire.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Fifty patients (mean age, 27 years) with <25% glenoid defect who were treated with arthroscopic Bankart repair for recurrent anterior dislocation were assessed at a mean follow-up of 28 months. All had an on-track Hill-Sachs lesion. The Western Ontario Shoulder Instability Index (WOSI) and Rowe scores were used for the clinical evaluation. The Hill-Sachs interval was measured on 3-dimensional computed tomography images and divided by the glenoid track width, defined as the Hill-Sachs occupancy (in percentages). The glenoid track was divided into 4 zones based on the percentage of the Hill-Sachs occupancy: zone 1, <25%; zone 2, 25% to <50%; zone 3, 50% to <75%; and zone 4, ≥75%.

RESULTS

The recurrence rate was 6% (3 of 50 shoulders). The Rowe score significantly improved from 45.2 ± 4.7 (mean ± SD) preoperatively to 92.3 ± 6.5 at the final follow-up (P < .05). The WOSI score also significantly increased from 46.6% ± 19.3% preoperatively to 72.3% ± 21.0% at the final follow-up (P < .001). The WOSI score of patients in zone 4 (peripheral-track lesion) (n = 10) was significantly lower than those in the other zones (central-track lesion) (P = .0379). Of the 10 patients with the peripheral-track lesion, 5 had a <40% WOSI score, similar to the preoperative WOSI score (46.6%).

CONCLUSION

Patients with on-track lesions can be divided into 2 subgroups: those with the Hill-Sachs occupancy ≥75% (peripheral-track lesion) showed significantly worse WOSI score without recurrent instability events than those with the Hill-Sacks occupancy <75% (central-track lesion).

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.

Off-track Hill-Sachs lesions do not increase postoperative recurrent instability after arthroscopic Bankart repair with selective Remplissage procedure

PURPOSE

This study aimed to compare clinical outcomes and recurrence rates after arthroscopic Bankart repair with selective Remplissage procedure, between patients with off-track and on-track Hill-Sachs lesions.

METHODS

Patients who underwent arthroscopic Bankart repair with selective Remplissage procedure for recurrent anterior shoulder instability and were followed up for at least 2 years were included. Patients with a glenoid defect greater than 25% were excluded. According to the glenoid track concept, patients were divided into group I (off-track lesions) and group II (on-track lesions). After Bankart repair, an additional Remplissage procedure was performed selectively in patients who sustained engagement of the humeral head. The clinical outcomes and recurrence rates were evaluated.

RESULTS

A total of 193 patients (23 in group I and 170 in group II) were enrolled. No significant differences were found in clinical outcomes (n.s.) or recurrence rates (n.s.) between the two groups, despite larger glenoid defects in group I (group I:17.1 ± 6.1%, and group II:13.0 ± 6.4%, P = 0.003). In all patients, the incidence of off-track lesions was not significantly different according to the occurrence of postoperative recurrence (n.s.), whereas the glenoid defect size showed a significant difference (with recurrence: 17.9 ± 3.9%, and without recurrence: 13.2 ± 6.5%, P = 0.002).

CONCLUSIONS

The presence of an off-track lesion did not alter the clinical outcomes and recurrence rates after arthroscopic Bankart repair with selective Remplissage procedure. The glenoid defect size rather than the presence of an off-track lesion can more reliably predict postoperative recurrence. Arthroscopic Bankart repair with selective Remplissage procedure is considered one surgical option for the treatment of off-track lesions.

LEVEL OF EVIDENCE

III.

Risk of Recurrent Instability After Arthroscopic Stabilization for Shoulder Instability in Adolescent Patients

Background:

With the rise of adolescent sports participation, there has been a concomitant increase in not only the incidence but also the treatment of traumatic shoulder instability. Yet, there have been limited data on the failure rates of arthroscopic shoulder stabilization in this population as well as the potential risk factors.

Purpose/Hypothesis:

The purpose of this study was to determine the failure rates of adolescent patients who underwent arthroscopic labral reconstruction for traumatic anterior shoulder instability. We hypothesized that adolescent failure rates would be significantly higher than what has been reported in the adult population with regard to recurrent instability after surgical intervention.

Study Design:

Case series; Level of evidence, 4.

Methods:

This was a retrospective cohort study performed at a single center. Inclusion criteria consisted of all adolescent-aged patients identified who (1) had traumatic anterior shoulder instability, (2) had radiographic findings consistent with anteroinferior capsulolabral injury, and (3) underwent arthroscopic shoulder stabilization. Patient demographics, clinical presentation, imaging, intraoperative findings, and postoperative outcomes were analyzed.

Results:

A total of 36 patients were identified, with a mean ± SD follow-up of 35.6 ± 13.8 months. The mean patient age at the time of the index procedure was 16.03 ± 1.67 years. All patients underwent arthroscopic shoulder stabilization consisting of arthroscopic Bankart repair. Twelve patients (33.3%) reported either recurrent instability or apprehension, of whom 9 (25.0%) developed recurrent dislocation/subluxation at a mean of 20.67 months postoperatively (range, 16-51 months). No single sport was associated with a statistically significant increased risk of redislocation, although a trend was seen toward those with postoperative participation in high-risk sporting activity. Patients who redislocated their shoulders had a higher frequency of a Hill-Sachs lesion on magnetic resonance imaging (89%) compared with those who did not (52%, P = .048). History of multiple preoperative dislocations, presence of bony Bankart pathology, off-track lesions, and number of anchors utilized were not associated with postoperative dislocation/subluxation.

Conclusion:

This study demonstrates that adolescent patients treated with arthroscopic shoulder stabilization have a high rate of recurrent instability. The adolescent population may benefit from other stabilization strategies and/or activity modification. Further studies are necessary to determine the reasons for the high rate of redislocation and to develop strategies for prevention.

Management of Recurrent Anterior Shoulder Instability With Bipolar Bone Loss: A Systematic Review to Assess Critical Bone Loss Amounts

BACKGROUND

There is increasing evidence to suggest that the amount of glenoid bone loss to indicate bone block procedures may be lower than previously thought, particularly in the presence of a Hill-Sachs defect.

PURPOSE

To better establish treatment recommendations for anterior shoulder instability among patients with bipolar bone lesions.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

A systematic review of the literature was performed with PubMed, EMBASE, Cochrane Library, and Scopus databases according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. Studies evaluating outcomes of operative management in anterior shoulder instability that also reported glenoid bone loss in the presence of Hill-Sachs defects were included. Recurrence rates, glenoid bone loss, and humeral bone loss were pooled and analyzed with forest plots stratified by surgical procedure. Methods of quantification were analyzed for each article qualitatively.

RESULTS

Thirteen articles were included in the final analysis, with a total of 778 patients. The mean ± SD age was 24.9 ± 8.6 years. The mean follow-up was 30.1 months (range, 11-240 months). Only 13 of 408 (3.2%) reviewed bipolar bone loss articles quantified humeral and/or glenoid bone loss. Latarjet procedures had the greatest glenoid bone loss (21.7%; 95% CI, 14.8%-28.6%), followed by Bankart repairs (13.1%; 95% CI, 9.0%-17.2%), and remplissage (11.7%; 95% CI, 5.5%-18.0%). Humeral bone loss was primarily reported as percentage bone loss (22.2%; 95% CI, 13.1%-31.3% in Bankart repairs and 31.7%; 95% CI, 21.6%-41.1% in Latarjet) or as volumetric defects (439.1 mm³; 95% CI, 336.3-541.9 mm³ in Bankart repairs and 366.0 mm³; 95% CI, 258.4-475.4 mm³ in remplissage). Recurrence rates were as follows: Bankart repairs, 19.5% (95% CI, 14.5%-25.8%); remplissage, 4.4% (95% CI, 1.3%-14.0%); and Latarjet, 8.7% (95% CI, 5.0%-14.7%). Bankart repairs were associated with significantly greater recurrence of instability in included articles (P = .013).

CONCLUSION

There exists a need for universal and consistent preoperative measurement of humeral-sided bone loss. The presence of concomitant Hill-Sachs defects with glenoid pathology should warrant more aggressive operative management through use of bone block procedures. Previously established values of critical glenoid bone loss are not equally relevant in the presence of bipolar bone loss.

[Current concepts of diagnostic techniques and measurement methods for bone defect in patient with anterior shoulder instability]

Objective

To summarize the diagnosis and measurement methods of bone defect in anterior shoulder instability (glenoid bone defect and Hill-Sachs lesion).

Methods

The related literature on the diagnosis and measurement of the bone defect in anterior shoulder instability was reviewed and summarized.

Results

The commonly used techniques for the diagnosis of anterior glenoid bone defect and Hill-Sachs lesion of humeral head include X-ray, CT, MRI, arthroscopy, arthrography. The methods for measuring the degree of anterior glenoid bone defect include Griffith method, glenoid index method, Pico method, and best-fit circle method. The indexes for measuring the Hill-Sachs lesion include the length, width, depth, and volume. X-ray is mainly used for primary screening. Best-fit circle method on three-dimensional (3D) CT reconstruction is commonly used to measure the glenoid bone defect currently. Glenoid track theory on 3D CT reconstruction is popular in recent years. Reliability of measuring the glenoid bone defect and Hill-Sachs lesion with MRI and arthroscopy is still debatable. Arthrography is more and more used in the diagnosis of shoulder joint instability of bone defect and concomitant soft tissue injury.

Conclusion

How to improve the accuracy of evaluating glenoid bone defect and Hill-Sachs lesion before surgery still need further study.

Hill-Sachs Lesion Classification by the Glenoid Track Paradigm in Shoulder Instability: Poor Agreement Between 3-Dimensional Computed Tomographic and Arthroscopic Methods

PURPOSE

The purpose of this study was to determine the amount of agreement between preoperative 3-dimensional computed tomographic (3D-CT) and intraoperative arthroscopic classification of Hill-Sachs lesions (HSLs) according to the glenoid track (GT) paradigm.

METHODS

Records for patients treated surgically for anterior shoulder instability from a single surgeon's practice from August 2013 until March 2016 were retrospectively reviewed. Inclusion criteria were presence of an HSL, < 25% glenoid bone loss, bilateral 3D-CT, and arthroscopically recorded bone loss measurements. Records for patients with chronic dislocations or prior operations were excluded. Calculations by 3D-CT and arthroscopy were performed as follows: Hill-Sachs interval (HSI) was the distance from rotator cuff insertion to medial edge of the HSL; GT was 83% of the normal glenoid width minus any glenoid defect; on-track was HSI less than GT; off-track was HSI greater than GT.

RESULTS

Sixteen shoulders with HSL status determined as on- or off-track demonstrated agreement between the 2 methods in 10 of 16 cases (63%, Cohen's κ = 0.16). All 6 cases with disagreement were calculated as on-track by 3D-CT and off-track by arthroscopic measurement. The GT was larger as determined by 3D-CT measurement (22 ± 1 mm [21-24]) compared with arthroscopy (18 ± 1 mm [17-20], P = .002).

CONCLUSIONS

Preoperative 3D-CT showed slight agreement compared with intraoperative arthroscopic measurements in classifying HSL as on-track versus off-track in the GT paradigm; larger GT size by 3D-CT versus arthroscopy accounted for all discrepancies. Determination of off-track status based on preoperative 3D-CT versus determination with the arthroscopic method would result in fewer HSLs treated with remplissage if the GT treatment paradigm were followed. Surgeons using the GT paradigm to determine treatment of HSL by remplissage should recognize the potential for discordance between arthroscopic and radiographic measurements.

Surgical decision making based on the on-track/off-track concept for anterior shoulder instability: a case-control study

Background

The purpose of this study was to assess the clinical outcomes of patients with anterior shoulder instability who underwent surgical treatment according to the on-track/off-track concept.

Methods

We retrospectively analyzed patients who underwent surgical treatment according to the glenoid track concept with a minimum of 2 years’ follow-up. By use of preoperative 3-dimensional computed tomography images, surgical options were selected: arthroscopic Bankart repair (ABR) for patients with on-track lesions and the Latarjet procedure or ABR with the remplissage procedure for patients with off-track lesions. The recurrence rate was assessed at 2-year follow-up after surgery.

Results

Among 92 patients enrolled in this study, 81 had on-track lesions and underwent ABR. Of the 11 patients with off-track lesions, 1 underwent ABR with the remplissage procedure and 10 underwent the Latarjet procedure. Recurrences occurred in 4 patients treated by ABR (5%), whereas no recurrences were observed in off-track cases treated by the remplissage or Latarjet procedure.

Conclusion

Clinical application of the on-track/off-track concept for determining surgical options in preoperative planning seems to be useful to prevent recurrent instability after surgery.