Glenoid Track Concept Research Articles

Management of bone loss in anterior shoulder instability.

Bone defects are frequently observed in anterior shoulder instability. Over the last decade, knowledge of the association of bone loss with increased failure rates of soft-tissue repair has shifted the surgical management of chronic shoulder instability. On the glenoid side, there is no controversy about the critical glenoid bone loss being 20%. However, poor outcomes have been described even with a subcritical glenoid bone defect as low as 13.5%. On the humeral side, the Hill-Sachs lesion should be evaluated concomitantly with the glenoid defect as the two sides of the same bipolar lesion which interact in the instability process, as described by the glenoid track concept. We advocate adding remplissage to every Bankart repair in patients with a Hill-Sachs lesion, regardless of the glenoid bone loss. When critical or subcritical glenoid bone loss occurs in active patients (> 15%) or bipolar off-track lesions, we should consider anterior glenoid bone reconstructions. The techniques have evolved significantly over the last two decades, moving from open procedures to arthroscopic, and from screw fixation to metal-free fixation. The new arthroscopic techniques of glenoid bone reconstruction procedures allow precise positioning of the graft, identification, and treatment of concomitant injuries with low morbidity and faster recovery. Given the problems associated with bone resorption and metal hardware protrusion, the new metal-free techniques for Latarjet or free bone block procedures seem a good solution to avoid these complications, although no long-term data are yet available.

Similar outcomes in collision athletes with subcritical glenoid bone loss and on-Track Hill Sachs lesion versus off-track Hill Sachs lesion managed with open Bankart repair plus inferior capsular shift.

Open Bankart repair plus inferior capsular shift has not yet been tested under the concept of glenoid track as a predictor of failure. The aim of this study was to compare the subjective and objective outcomes in collision athletes with subcritical glenoid bone loss and on-track Hill Sachs lesions versus those with off-track Hill Sachs lesions, all treated with open Bankart repair. Two study groups were created: 50 patients had on-track Hill Sachs lesions, while 38 had off-track lesions. The subcritical glenoid bone loss was ≤ 10%. A minimum follow-up period of 3 years was established. Preoperative and postoperative evaluation of each group and between them was performed. The Western Ontario Shoulder Instability Index score and the American Shoulder and Elbow Surgeons scale were used to assess subjective outcomes. Recurrence rate, range of motion and return to sport were evaluated as objective outcomes. Significant differences were reported in the WOSI and ASES scores between preoperative and postoperative values in each group. There were no significant differences between the two groups (p-value = 0.36 and 0.71). Three dislocations (6%) in the on-track group and 3 (7.8%) in the off-track group were recorded, showing no differences between the two groups (p-value = 0.83). There were no differences in ROM between pre- and post-operatively in each group or when comparing the two groups. We found no differences between the outcomes of the two groups. According to the surgeon's preference, we recommend performing open Bankart repair plus inferior capsular shift as a treatment alternative in collision athletes with SGBL ≤ 10% independently of the type of Hill Sachs lesion.

Poster 111: MRI Offers Greater Reliability for Assessment of Glenoid Track Concept than CT

Poster 111: MRI Offers Greater Reliability for Assessment of Glenoid Track Concept than CT

Open Bankart repair plus inferior capsular shift versus isolated arthroscopic Bankart repair in collision athletes with recurrent anterior shoulder instability: a prospective study

BackgroundOpen Bankart repair plus inferior capsular shift and isolated arthroscopic Bankart repair have never been prospectively compared under the concept of glenoid track in collision athletes with recurrent anterior shoulder instability. The aim of this study was to compare the functional outcomes, range of motion and recurrence rate between these two surgical techniques. We hypothesized that open Bankart repair plus inferior capsular shift would provide similar functional outcomes to isolated arthroscopic Bankart repair but with a lower recurrence rate. MethodsA prospective cohort study was conducted with 86 collision athletes divided into two groups of 43 patients each. All patients had a subcritical glenoid bone loss ≤ 13.5% and an on-track Hill Sachs lesion. The average follow-up was 66 (60-93) months for the open group and 68 (60-97) months for the arthroscopic group. The primary functional outcomes of each group were evaluated at baseline, 6 months, 1 year and for a minimum of 5 years after surgery. The functional outcomes were also compared between the two groups. The assessment tools included the WOSI and ASES scores. In addition, recurrent instability and range of motion were also evaluated. ResultsIn each group, there were significant differences in WOSI and ASES scores between the pre and postoperative periods. There were no differences between the groups at the end of follow-up (P = 0.47 and 0.22). Three dislocations (6.9%) in the open group and 10 dislocations (23.2%) in the arthroscopic group were reported showing significant differences (P = .012). In addition, there were no differences in range of motion between pre and postoperative periods for each group as well as between them. ConclusionWe found no differences in functional outcomes and range of motion between the two groups. The recurrence rate was significantly higher in the arthroscopic group. We recommend performing open Bankart repair plus inferior capsular shift as a treatment alternative in collision athletes with recurrent anterior shoulder instability.

Effective glenoid track: A novel concept for shoulder instability

BackgroundAssessment and quantification of bone loss in cases of shoulder instability is critical for surgical decision making. The glenoid track concept was initially developed to assess Hill Sachs lesions taking into account the native glenoid diameter of the contralateral shoulder and assessing the degree of glenoid bone loss. However, it can not be reverse calculated to determine the effect of an addition of a bone block. We have developed a novel model to help address this problem yielding an “effective glenoid track” (EGT). MethodsBegin as we always do by using Itoi's concept for assessment of tracking based on the CT scan cuts. Next step is to calucate the Hill Sach's interval (HSI) which will require an MRI scan. ConclusionThe EGT allows for calculation of residual tracking of Hill Sachs lesions post a bone block addition and will aid in surgical decision making.

The Global Track Concept for Assessment of Engaging Hill-Sachs Defects in Anterior Shoulder Instability

Background: The glenoid track concept is used to determine preoperatively whether a Hill-Sachs defect is engaging or not. Currently, the glenoid track concept relies on measurements of bony structures as well as on the confines and elasticity of the rotator cuff as a reference point, which varies extensively among individuals and therefore limits the reliability and accuracy of this concept. Purpose: To evaluate the reliability of the global track concept, which determines the angular distance of the Hill-Sachs defect from the center of the articular surface of the humeral head as a new reference point with the help of an automated image analysis software and 3-dimensional analysis of the humeral head. Study Design: Controlled laboratory study. Methods: Computed tomography scans of 100 patients treated for anterior shoulder instability with different sizes of Hill-Sachs defects were evaluated manually by 2 orthopaedic surgeons independently using the software OsiriX as well as automatically by using a dedicated prototype software (ImFusion). Obtained manual and automated measurements included the Hill-Sachs length, Hill-Sachs width, and Hill-Sachs depth of the defect; the Hill-Sachs interval (HSI); and the glenoid width for the glenoid track concept, as well as the angular distance of the Hill-Sachs defect from the center of the articular surface of the humeral head (global track concept). The reliability of the different measurement techniques was compared by calculating intraclass correlation coefficients (ICCs). Results: There was a significant difference for all obtained parameters comparing manual and automatic measurements. For manually obtained parameters, measurements referring to bony boundaries (glenoid width, Hill-Sachs length, and Hill-Sachs width) showed good to excellent agreement (ICC, 0.86, 0.82, and 0.62, respectively), while measurements referring to soft tissue boundaries (HSI and glenoid track; ICC, 0.56 and 0.53, respectively) or not directly identifiable reference points (center of articular surface and global track) only showed fair reliability (ICC middle excursion, 0.42). When the same parameters were measured with the help of an automated software, good reliability for the glenoid track concept and excellent reliability for the global track concept in the middle excursion were achieved. Conclusion: The present study showed that the more complex global track measurements of humeral defects are more reliable than the current standard HSI and glenoid track measurements. However, this is only true when automated software is used to perform the measurements. Clinical Relevance: Future studies using the new proposed method in combination with an automated software need to be conducted to determine critical threshold values for defects prone to engagement.

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

BackgroundThe glenoid track concept identifies patients with “off-track” (engaging) Hill-Sachs lesions (HSLs) as poor candidates for arthroscopic Bankart repair (ABR) due to high risk of shoulder instability recurrence. PurposeTo 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”) Hill-Sachs lesions on preoperative CT-scan. Type of StudyComputed tomography scan study MethodsPreoperative computed tomography (CT) scan of 45 patients, seen in our facility for failed ABR, were 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 Hill-Sachs 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). ResultsPreoperative 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 two groups (off-track versus 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 Hill-Sachs width was greater than 20mm 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 versus 6.6 ±1.7, p=0.453). 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 versus 6.6 ±1.7). ConclusionsThe 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.

Longer peripheral-track lesions are associated with instability after arthroscopic Bankart repair

BackgroundThe Glenoid track concept has enabled the categorization of Hill-Sachs lesions (HSLs) into on-track lesions and off-track lesions. Furthermore, among the on-track lesions, further categorization has been established based on the distance from the medial edge of the Hill-Sachs lesion to the medial edge of the glenoid track, into peripheral-track lesions and central-track lesions. Recent studies on peripheral-track lesions and central-track lesions within the glenoid track have shown inconsistencies in failure rates, which deserves further investigation. MethodsA retrospective cohort comparison of patients who underwent arthroscopic Bankart repair between 2015 and 2020 was performed. 102 patients with peripheral-track HSLs were included. The patients were divided into two groups based on the results of the postoperative apprehension test: the apprehension positive group (n=30), and the apprehension negative group (n=72). Using preoperative computed tomography and an image reconstruction program, three-dimensional images were segmented to calculate the length, width, depth, and distance of the HSLs. A multivariate logistic regression was used to determine the risk factors of recurrence, for which odds ratio (OR) and 95% confidence interval (CI) were provided. ResultsA multivariate logistic regression analysis revealed that the length of the peripheral-track HSLs was a significant independent predictor of failure in this study. (OR 1.380; 95% CI 1.170–1.627; P<0.001). The receiver operating characteristics curve demonstrated a predictive power (area under the curve = 0.841) and a threshold value of 14.2 mm. ConclusionLength was the only risk factor for the recurrent instability of peripheral-track HSLs after ABR. In the context of surgical decision-making, utilizing the glenoid track concept, medical practitioners may need to evaluate instability by considering the length as a continuous factor, while differentiating between peripheral-track and central-track classifications.

Validating the Glenoid Track Concept Using Dynamic Arthroscopic Assessment.

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. To determine the accuracy and reliability of using the glenoid track concept against dynamic arthroscopic assessment of Hill-Sachs lesion engagement. Cohort study (diagnosis); Level of evidence, 3. 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. 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). 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.

Defining Critical Humeral Bone Loss: Inferior Craniocaudal Hill-Sachs Extension as Predictor of Recurrent Instability After Primary Arthroscopic Bankart Repair

Background: The glenoid track concept for shoulder instability primarily describes the medial-lateral relationship between a Hill-Sachs lesion and the glenoid. However, the Hill-Sachs position in the craniocaudal dimension has not been thoroughly studied. Hypothesis: Hill-Sachs lesions with greater inferior extension are associated with increased risk of recurrent instability after primary arthroscopic Bankart repair. Study Design: Case-control study; Level of evidence, 3. Methods: The authors performed a retrospective analysis of patients with on-track Hill-Sachs lesions who underwent primary arthroscopic Bankart repair (without remplissage) between 2007 and 2019 and had a minimum 2-year follow-up. Recurrent instability was defined as recurrent dislocation or subluxation after the index procedure. The craniocaudal position of the Hill-Sachs lesion was measured against the midhumeral axis on sagittal magnetic resonance imaging (MRI) using either a Hill-Sachs bisecting line through the humeral head center (sagittal midpoint angle [SMA], a measure of Hill-Sachs craniocaudal position) or a line tangent to the inferior Hill-Sachs edge (lower-edge angle [LEA], a measure of Hill-Sachs caudal extension). Univariate and multivariate regression were used to determine the predictive value of both SMA and LEA for recurrent instability. Results: In total, 176 patients were included with a mean age of 20.6 years, mean follow-up of 5.9 years, and contact sport participation of 69.3%. Of these patients, 42 (23.9%) experienced recurrent instability (30 dislocations, 12 subluxations) at a mean time of 1.7 years after surgery. Recurrent instability was found to be significantly associated with LEA >90° (ie, Hill-Sachs lesions extending below the humeral head equator), with an OR of 3.29 (P = .022). SMA predicted recurrent instability to a lesser degree (OR, 2.22; P = .052). Post hoc evaluation demonstrated that LEA >90° predicted recurrent dislocations (subset of recurrent instability) with an OR of 4.80 (P = .003). LEA and SMA were found to be collinear with Hill-Sachs interval and distance to dislocation, suggesting that greater LEA and SMA proportionally reflect lesion severity in both the craniocaudal and medial-lateral dimensions. Conclusion: Inferior extension of an otherwise on-track Hill-Sachs lesion is a highly predictive risk factor for recurrent instability after primary arthroscopic Bankart repair. Evaluation of Hill-Sachs extension below the humeral equator (inferior equatorial extension) on sagittal MRI is a clinically facile screening tool for higher-risk lesions with subcritical glenoid bone loss. This threshold for critical humeral bone loss may inform surgical stratification for procedures such as remplissage or other approaches for at-risk on-track lesions.

Association of Instability History and Off-Track Hill-Sachs Lesions in Anterior Shoulder Instability.

The glenoid track concept is now widely accepted, and its evaluation is considered essential for making decisions about surgery. To define preoperative descriptive data and clinical and functional features in patients with anterior glenohumeral instability according to glenoid track status and to analyze the influence of off-track Hill-Sachs (HS) lesions on preoperative shoulder function. Case-control study; Level of evidence, 3. Preoperative magnetic resonance imaging or computed tomography scans were used to measure the glenoid track. Descriptive data and preoperative objective and subjective clinical and functional features were compared between patients with on-track HS lesions versus off-track HS lesions. Multivariate regression analysis was conducted to identify potential risk factors for off-track HS lesion development. A total of 235 patients (201 men, 34 women; mean age, 29.6 ± 8.6 years) were included- 134 shoulders (57%) with on-track HS lesions and 101 shoulders (43%) with off-track HS lesions. Age <20 years at first dislocation, number of dislocations, and ≥2 years between first dislocation and surgery were significantly different between the study groups (P = .005, P = .0001, and P = .01, respectively). Regarding these characteristics, the odds ratios for the risk of developing an off-track lesion were 2.67 (95% CI, 1.2-5.99)-1.2 times higher for each additional instability episode (95% CI, 1.025-1.14) and 2.42 times higher (95% CI, 1.176-4.608) for patients whose first dislocation was ≥2 years before surgery, respectively. Patients with off-track HS lesions had a significantly greater degree of instability (P = .04), worse Rowe scores (48.8 ± 15.3 vs 54.8 ± 28.3 for on-track HS lesions; P = .04), and lower Western Ontario Shoulder Instability scores (975 ± 454 vs 1179 ± 428 for on-track HS lesions; P = .01). Characteristics related to a history of instability (age <20 years at first instability episode, larger number of dislocations, ≥2 years between first dislocation and surgery) were found to be risk factors for the development of an off-track HS lesion in this study. Off-track lesions led to a higher degree of instability and worse objective and subjective preoperative shoulder function versus on-track HS lesions.

Current Concepts in the Measurement of Glenohumeral Bone Loss.

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 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.

Paper 01: Capsuloligamentous Laxity is a Risk Factor for Failure in Near Track Lesions Following Arthroscopic Anterior Shoulder Stabilization

Objectives: Recurrent anterior shoulder instability after arthroscopic Bankart repair presents a challenging clinical problem, with the primary stabilization procedure often portending the best chance for clinical success. While the glenoid track concept continues to evolve, a limitation of the glenoid track is that it relies on bony anatomy without specific considerations for capsuloligamentous integrity or the effect that capsular laxity may have on the glenohumeral contact points throughout shoulder range of motion. The purpose of the study was to determine if capsuloligamentous laxity has a modifying effect on the glenoid track, specifically for on-track lesions with a small distance to dislocation (DTD) from being an off-track lesion or the so-called “near-track” lesion. This may explain why some on-track lesions are at an increased risk of recurrent instability. We hypothesized that patients with ligamentous laxity and “near track” lesions would be at increased risk of recurrent instability following arthroscopic Bankart repair. Methods: Consecutive patients with on-track Hill-Sachs lesions who underwent primary arthroscopic Bankart repair alone without remplissage for recurrent anterior glenohumeral instability between January 2007 and December 2015 at a single institution were retrospectively reviewed. Patients with less than 2-year follow up, glenoid bone loss &gt; 20%, off-track lesions, concomitant remplissage, and atraumatic instability were excluded. Determination of shoulder laxity was based on exam under anesthesia (EUA), including anterior load and shift, posterior load and shift, and sulcus testing at the time of surgery before arthroscopy. Capsuloligamentous shoulder hyperlaxity was defined as external rotation of &gt;85o and/or grade of 2+ or greater load and shift in two or more planes. Measurements of glenoid bone loss, Hill-Sachs interval (HSI), and glenoid track (GT) were performed based on prior described methods. DTD was calculated (DTD=GT-HSI, with DTD&gt;0 classified as on-track lesions). Near track lesions were defined as 0&lt;DTD&lt;8mm. Failure was defined as recurrent dislocation. Results: A total of 173 patients were initially identified, of which 151 met inclusion criteria and were included for analysis. 72.8% of patients were males and mean age was 20.1 ± 5.7 years. Patients were divided into two groups based on shoulder laxity; group 1 consisted of 74 patients with hyperlaxity, and group 2 consisted of 77 patients without hyperlaxity. Overall, 21 patients (13.9%) sustained a recurrent dislocation and 35 patients (23.2%) had recurrent instability episodes. Failure was associated with glenoid bone loss (p&lt;0.001 ), longer HS length ( p=0.007), occurrence of &gt;1 instability episode preoperatively (p=0.018 ), and smaller DTD ( p=0.0008). Hyperlaxity was associated with the use of more anchors ( p=0.0001). Shoulder laxity was not independently predictive of overall failure (Figure 1, p=0.18); however, DTD was significantly associated with failure risk and recurrent instability in patients with hyperlaxity ( p=0.006) specifically in younger patients with hyperlaxity (Figure 1, Table 1). Conclusions: Our study suggests that while capsuloligamentous laxity is not independently predictive of failure after arthroscopic Bankart repair for on-track lesions, laxity may play a significant role in clinical outcomes in patients with a small DTD or near-track lesions. In younger patients with near-track lesions, hyperlaxity may be particularly predictive of failure after arthroscopic Bankart repair. As our understanding of the glenoid track continues to evolve, surgeons may need to consider the track concept as a continuum with evolving surgical algorithms other than an arthroscopic Bankart alone in young patients with near track lesions and hyperlaxity. [Table: see text]

Decision-Making in Anterior Shoulder Instability

The shoulder is the most frequently dislocated joint, accounting for more than half of all joint dislocations. Several classification systems have been proposed for glenohumeral instability. A physical exam is mandatory, despite which classification system is applied. When treating patients with anterior shoulder instability, surgeons must be aware of the subcritical and critical size of bone loss, which is commonly seen. The glenoid track concept may guide surgeons in decision-making by using the glenoid track measurement. A detailed assessment of the existing soft tissue injury to the labrum, capsule, glenohumeral ligaments, and rotator cuff is also mandatory, as their presence influences the surgical outcome. Non-operative measures such as rehabilitation, arthroscopic repair techniques, open Bankart procedure, remplissage, and bone-block procedures offer the surgeon different treatment options according to the characteristic of the patient and the lesions to be treated.

Distance to Dislocation and Recurrent Shoulder Dislocation After Arthroscopic Bankart Repair: Rethinking the Glenoid Track Concept

Background: The “distance to dislocation” (DTD) calculation has been proposed as 1 method to predict the risk of recurrent dislocation after arthroscopic Bankart repair for an “on-track” shoulder. Rates of recurrent dislocation at specific DTD values are unknown. Hypothesis: Among patients with “on-track” shoulder lesions who underwent primary arthroscopic Bankart repair, the rate of recurrent dislocation would increase as DTD values decrease. Study Design: Case-control study; Level of evidence, 3. Methods: We performed a retrospective analysis of 188 patients with “on-track” shoulder lesions who underwent primary arthroscopic anterior labral repair between 2007 and 2019, with a minimum 2-year follow-up. Glenoid bone loss, Hill-Sachs interval, glenoid track, and DTD were determined from preoperative magnetic resonance imaging scans. The rate of recurrent dislocation was determined at 2-mm DTD intervals. Univariate and multivariate regression analyses were used to evaluate the relationship between recurrent dislocation, patient characteristics, and bone loss variables. A multivariate regression model was created to predict the probability of failure at continuous DTD values. A subgroup analysis of failure rate based on collision sports participation was also performed. Results: A total of 29 patients (15.4%) sustained recurrent dislocations. Patient age (P = .046), multiple dislocations (P = .03), glenoid bone loss (P < .001), Hill-Sachs interval length (P < .001), and DTD (P < .001) were all independent predictors of failure. As the DTD decreased, the rate of recurrent dislocation increased. Below a DTD threshold of 10 mm, the recurrent dislocation rate increased exponentially. Up to a threshold of 24 mm, the failure rate for collision athletes remained >12.3%, independent of the DTD. Conversely, the failure rate among noncollision athletes decreased steadily as the DTD increased. Conclusion: For “on-track” shoulder lesions, as the DTD approached 0 mm (“off-track” threshold), the risk of recurrent dislocation after arthroscopic Bankart repair increased significantly. Below a DTD threshold of 10 mm, the risk of failure increased exponentially. The risk of recurrent dislocation for collision sports athletes remained elevated at higher DTD values than for noncollision athletes.

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.

High rate of return to sport and excellent patient-reported outcomes after an open Latarjet procedure.

The purpose of this study was to report return to sport, patient-reported outcomes (PROs), subjective outcomes, and complications or failures in patients who underwent open Latarjet surgery. Patients who underwent open Latarjet surgery performed by 2 fellowship-trained surgeons between August 2006 and November 2018 were included. Prospectively collected data were reviewed. Recurrent instability and revision surgical procedures were recorded. Subjective outcomes included return to sport and fear of reinjury or activity modification as a result of patients' instability history. PROs included the American Shoulder and Elbow Surgeons (ASES) score, Short Form 12 Physical Component Summary score, Single Assessment Numeric Evaluation score, Quick Disabilities of the Arm, Shoulder and Hand score, and satisfaction. Age, sex, sports participation, pain, primary vs. revision surgery (prior failed arthroscopic or open Bankart repair), dislocation number, glenoid bone loss, glenoid track concept, and projected glenoid track were evaluated. Failure was defined as an ASES score <70, recurrent dislocation, or revision instability surgery. A total of 126 shoulders (125 patients) met the inclusion criteria, with a mean age of 28.1 years (range, 15-57 years). Of 126 shoulders, 7 (5.5%) underwent additional procedures prior to final follow-up and were excluded from outcome analyses; failure occurred in 6 of these shoulders. Mean follow-up data at 3.7 years (range, 2-9.3 years) were attained in 86.6% of patients (103 of 119). All PROs significantly improved from preoperative baseline (ASES score, from 69.7 to 90.2; Single Assessment Numeric Evaluation score, from 55.8 to 85.9; and Quick Disabilities of the Arm, Shoulder and Hand score, from 28.4 to 10.5). PROs did not differ based on sex, sports participation type, dislocation with or without sports, primary vs. revision procedure, and preoperative dislocation number. No correlations existed between PROs and age, glenoid bone loss, or number of previous surgical procedures. On-track lesions (50 of 105, 47.6%) and projected on-track lesions (90 of 105, 85.7%) correlated with better patient satisfaction but not PROs. Despite not having recurrences, 63 of 99 patients (63.6%) reported activity modifications and 44 of 99 patients (44.4%) feared reinjury. These groups had statistically worse PROs, although the minimal clinically important difference was not met. Return to sport was reported by 97% of patients (86 of 89), with 74% (66 of 89) returning at the same level or slightly below the preinjury level. Revision stabilization surgery was required 6 of 126 cases (4.8%), and 6 of 103 shoulders (5.8%) had ASES scores <70. The open Latarjet procedure led to significant improvements in all PROs, and overall, 97% of patients returned to sport. Fear of reinjury and activity modifications were common after open Latarjet procedures but did not appear to affect clinical outcomes. On-track and projected on-track measurements correlated with better patient satisfaction but not improved PROs.

The Glenoid Track Concept: On-Track and Off-Track—A Narrative Review

Shoulder instability is described as a functional deficiency caused by excessive mobility of the humeral head over the glenoid. Various Glenohumeral Instability (GI) types have been described, but the traumatic anteroinferior form is the most frequent. The differences between engaging and non-engaging Hill–Sachs lesions (HSLs) are linked to bone loss assessment. On the contrary, the novel difference between “on-track” and “off-track” lesions is strictly related to surgical techniques. The specific involvement of glenoid and humerus bone defects in recurrent GI was poorly assessed in the literature before the glenoid-track concept (GT). Magnetic Resonance Imaging (MRI) and Arthro-MRI have been widely used to identify and characterize lesions to the ligamentous structures. However, only new technologies (3 Tesla MRI) accurately detect HSLs. On the contrary, Computed Tomography (CT) has been adopted to quantify glenoid bone deficit. The GT concept is a valuable tool for evaluating anterior shoulder instability in patients. Shoulders out of alignment may require more than just an arthroscopic Bankart, and a remplissage or bone transfer may be necessary. Specifically, isolated Bankart repair should be considered in patients with recurrent instability and an on-track lesion with less than 25% glenoid bone loss. In off-track lesions and less than 25% glenoid bone loss, remplissage should be used. Bone transplant surgery is required for patients with a glenoid bone defect of more than 25%. This narrative review aims to report the most updated findings on “on-track” and “off-track” lesions in GI.

Paper 70: "Distance to Dislocation" as a Predictor of Surgical Failure Following Primary Arthroscopic Anterior Labral Repair: Rethinking the Glenoid Track Concept

Objectives:Larger amounts of bipolar bone loss have a strong association with shoulder re-dislocation following arthroscopic labral repair. Development of the Glenoid Track (GT) concept has helped propose bone loss cut-offs for shoulders that should not be managed with arthroscopic labral repair alone. Recent literature has suggested the use of the glenoid track as a continuous variable rather than a binary “on-track/off-track” concept. The re-dislocation risk for “on-track” shoulders with smaller distances to dislocation (DTD), or “near-track” shoulders, has not been previously described. We hypothesized that decreasing DTD, or on-track lesions approaching an off-track lesion, would result in an increased risk of failure following arthroscopic Bankart repair alone.Methods:We performed a retrospective analysis of 197 patients who had undergone primary arthroscopic anterior labral repair between 2007 and 2019 with minimum 2-year follow-up. Glenoid bone loss using a perfect-circle method and Hills-Sachs (HS) interval, were measured from pre-operative MRIs. GT was calculated using previously described methods. Surgical failure was defined as a patient who re-dislocated their shoulder following surgery. DTD was calculated by subtracting the HS measurement from the GT calculation. Patients with “off-track” lesions (negative DTD), and those who had undergone a concomitant arthroscopic remplissage were excluded. We performed a logistical regression model to evaluate the relationship between surgical failure and DTD, glenoid bone loss, Hill-Sachs lesion size, number of anchors used, and patient age. We then created a risk estimator tool that calculates the risk of dislocation with DTD as a continuous variable.Results:Twenty-eight patients (14%) sustained recurrent shoulder dislocations following anterior shoulder labral repair. Average follow up was 7.8 years and there were no demographic differences between those with recurrence and those without (p>0.05). All patients had less than 25% glenoid bone loss (range 0-23%). Increased DTD (p < 0.0005) and glenoid bone loss (p < 0.0005) were independent predictors of surgical failure. After adjusting for glenoid bone loss and patient age, logistic regression modeling showed that for every 1mm decrease in DTD, there was an associated 13.6% increase in re-dislocation risk (p = 0.003). Patient age, Hill-Sachs length, participation in collision sports, and number of anchors used were not significantly associated with failure risk (p>0.05). A DTD <10mm had a 4.26 times greater odds of failure compared to those with DTD >10mm (OR 4.26; 95% CI 1.57-11.65; p = 0.005). The risk estimator tool developed using a logistic regression modeling demonstrated a 19% risk of failure for DTD 10mm, 26% risk for DTD 8mm, 36% risk for DTD 6mm, 49% risk for DTD 4mm, and 67% risk for DTD 2mm after adjusting for glenoid bone loss and patient age (Figure 1).Conclusions:The main finding of this study was that on-track lesions approaching off-track lesions, the so-called “near track” lesions, are associated with an exponentially increased risk of recurrent dislocation following primary arthroscopic anterior stabilization with labral repair alone. Furthermore, DTD values of <10mm were associated with the highest odds ratios for failure and were 4 times more likely to fail than for patients with DTD values >10mm. All of the patients included in this analysis had “on-track” shoulder lesions and <25% glenoid bone loss. Historically, these values have been identified as “cut-offs” used to identify patients who can be treated successfully with arthroscopic labral repair without a remplissage or other augmentation. DTD is a simple calculation for bipolar bone loss that can be used to predict risk of recurrent dislocation. Our results demonstrate potential pitfalls in making treatment decisions for bipolar bone loss using a binary “on-track, off-track” construct. Rather, the glenoid track concept applied as a continuum may be more useful for optimizing treatment.“On-track” shoulder lesions <10mm with diminishing DTD have a substantially higher risk of surgical failure with arthroscopic labral repair alone. As the DTD approaches 0mm (“off track lesion”), the risk of failure increases exponentially. When making treatment decisions for shoulder instability, bipolar bone loss should be viewed as a continuum rather than discreet “on-track, off-track” entities. For high-risk patients with a DTD approaching 0mm, additional augmentation with remplissage or open approaches should be considered.DTD can be used to estimate patient’s risk of recurrent dislocation following primary arthroscopic anterior labral repair for treatment of anterior shoulder instability. Application of this calculation would help surgeons decide the best surgical treatment for patients following anterior shoulder dislocation and can be particularly valuable for high risk patients. Understanding the association between lower DTD values and failure can also help inform the surgeon and patient regarding the risks and benefits of available treatment options.

Poster 135: Minimum 2 year Clinical Outcomes after Latarjet for anterior shoulder instability: clinical and imaging factors that correlate with success or failure

Objectives:The open Latarjet procedure has been demonstrated to be reliable in achieving acceptable patient reported outcomes (PROs). However, clinical predictors of outcome, return to sport and complications/failures have been more variable. The purpose of this study is to report patient reported outcomes (PROs), clinical correlations, and predictors of failure in patients who have received an open Latarjet surgery.Methods:Patients who received an open Latarjet with by two fellowship–trained surgeons between August 2006 - November 2018 were included. Prospectively collected data was reviewed, and PROs included ASES, SF–12 PCS, SANE, QuickDASH, and satisfaction. Age, sex, sports participation, pain, primary vs. revision (prior failed arthroscopic/open Bankart) surgery, dislocation number, glenoid bone loss (GBL), glenoid track concept, and projected glenoid track were evaluated. Projected track was calculated using the axial diameter of the corcoid as part of the glenoid track concept. Postoperative ASES <70, recurrent dislocation, or revision instability surgery were considered failures.Results:126 shoulders (125 patients) met inclusion criteria with mean age of 28.1 years (range 15–57). 7/126 (5.5%) had revision surgery prior to final follow-up and were excluded from outcomes analyses. Mean follow-up 3.7 years (range 2–9.3 years) was attained in 86.6% (103/119) of patients. All PROs significantly improved from preoperative baseline (ASES: 69.7→90.2; SANE: 55.8→85.9; QuickDASH: 28.4→10.5). PROs did not differ with sex, sport participation type, dislocation with/without sports, primary/revision, and preoperative dislocation number. No correlations existed between PROs and age, GBL, or number of previous surgeries. On-track (50/105, 47.6%) and projected on-track (90/105, 85.7%) lesions correlated with better patient satisfaction, but not PROs. A total of 97% (86/89) returned to sport, with 74% (66/89) at the same/slightly below pre-injury level. Failures included 13/126 (10.3%) postoperative dislocations and 6/126 (4.7%) with ASES scores <70.Conclusions:The open Latarjet procedure lead to significant improvements in all PROs, and overall 97% of patients returned to sport. On-track and projected on-track measurements correlated with better patient satisfaction, but not improved PROs. No other factors were predictive of outcomes, nor clinically correlated with failure.