Glenoid Track Concept Research Articles

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.

Belt and suspender technique for bipolar bone loss in shoulder instability

Bipolar glenohumeral bone loss is a challenging condition to address in patients with recurrent anterior shoulder instability. In this category of patients, most isolated soft-tissue procedures such as remplissage or infraspinatus capsulotenodesis are associated with high risk of failure and instability recurrence. Even bony procedures such as Latarjet may fail to provide absolute stability, and instability may eventually recur. For a better understanding of the cause of failure in this particular type of patient, we may refer to the glenoid track concept which has been described as a useful tool for surgical planning. In fact, Latarjet procedure alone may leave a place for engagement of the Hill-Sachs defect on the anterior glenoid resulting in an off-track situation and secondary glenohumeral instability. In this technical note, we present the combination of arthroscopic remplissage and an open Latarjet procedure to treat patients with bipolar glenohumeral bone loss with good results at 31-month follow-up. Our aim is to propose these techniques as a possible rescue procedure for highly unstable shoulders combining engaged Hill-Sachs lesion and glenoid bone loss of more than 25%. We believe this technique would be a good option for patients who present other risk factors of recurrence such as past medical history of epilepsy, laxity, and psychiatric illnesses.

Young Age And High Number Of Dislocations Predispose To Off-Track Hill-Sachs Lesions In Anterior Shoulder Instability

To define preoperative demographic, clinical and functional features of patients with anterior glenohumeral instability according to glenoid track concept and to analyze risk factors for the development of an off-track Hill-Sachs (HS) lesion.

Managing Bone Loss in Shoulder Instability-Techniques and Outcomes: a Scoping Review.

The aim of this scoping review is to provide an overview of the literature published over the past 5 years related to the management of bone loss in anterior shoulder instability. During recent years, there has been a focus on patients at high risk for failure following soft tissue anterior stabilization (Bankart repair). A growing body of evidence suggests that anterior capsulolabral repair is insufficient in the setting of subcritical glenoid bone loss with an off-track Hill Sachs lesion. In such cases, the addition of a remplissage procedure to a Bankart repair or a bone-block augmentation to the glenoid (Latarjet, for example) is often advocated to decrease the risk of recurrent instability. Recent studies have also evaluated the role of alternative bone-block procedures in comparison to the Latarjet, outcomes with arthroscopic and open techniques as well as various fixation methods and radiological outcomes (bone graft resorption, glenohumeral osteoarthritis). Advances in our understanding of subcritical glenoid bone loss and the glenoid track concept have significantly impacted clinical decision making and treatment selection. The development of arthroscopic techniques has allowed for minimally invasive and safe arthroscopic bone-block procedures as an alternative to open procedures. Further research related to free bone-block procedures will inform long-term outcomes between these procedures and the gold standard Latarjet. Additionally, high-quality evidence is lacking to identify the ideal treatment for patients with glenoid subcritical glenoid bone defect. Variability in outcome reporting suggests the need to standardize outcome measures for future instability trials.

Arthroscopy Limits on Anterior Shoulder Instability.

Much is discussed about the limits of the treatment of anterior shoulder instability by arthroscopy. The advance in understanding the biomechanical repercussions of bipolar lesions on shoulder stability, as well as in the identification of factors related to the higher risk of recurrence have helped us to define, more accurately, the limits of arthroscopic repair.We emphasize the importance of differentiation between glenoid bone loss due to erosion (GBLE) and glenoid edge fractures, because the prognosis of treatment differs between these forms of glenoid bone failure. In this context, we understand that there are three types of bone failure: a) bone Bankart (fracture); b) combined; and c) glenoid bone loss due to anterior erosion (GBLE), and we will address the suggested treatment options in each situation. Until recently, the choice of surgical method was basically made by the degree of bone involvement. With the evolution of knowledge, the biomechanics of bipolar lesions and the concept of glenoid track , the cutoff point of critical injury, has been altered with a downward trend. In addition to bone failures or losses, other variables were added and made the decision more complex, but a little more objective. The present update article aims to make a brief review of the anatomy with the main lesions found in instability; to address important details in arthroscopic surgical technique, especially in complex cases, and to bring current evidence on the issues of greatest divergence, seeking to guide the surgeon in decision making.

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.

On-Track Lesions with a Small Distance to Dislocation Are Associated with Failure After Arthroscopic Anterior Shoulder Stabilization.

Off-track lesions are strongly associated with failure after arthroscopic Bankart repair. However, on-track lesions with a small distance-to-dislocation (DTD) value, or "near-track lesions," also may be at risk for failure. The purpose of the present study was to determine the association of DTD with failure after arthroscopic Bankart repair. We performed a retrospective analysis of 173 individuals who underwent primary arthroscopic Bankart repair between 2007 and 2015. Glenoid bone loss and Hill-Sachs lesion size were measured with use of previously reported methods. Patients with failure were defined as those who sustained a dislocation after the index procedure, whereas controls were defined as individuals who did not. DTD was defined as the distance from the medial edge of the Hill-Sachs lesion to the medial edge of the glenoid track. Receiver operating characteristic (ROC) curves were constructed for DTD to determine the critical threshold that would best predict failure. The study population was subdivided into individuals ≥20 years old and <20 years old. Twenty-eight patients (16%) sustained a recurrent dislocation following Bankart repair. Increased glenoid bone loss (p < 0.001), longer Hill-Sachs lesion length (p < 0.001), and decreased DTD (p < 0.001) were independent predictors of failure. ROC curve analysis of DTD alone demonstrated that a threshold value of 8 mm could best predict failure (area under the curve [AUC] = 0.73). DTD had strong predictive power (AUC = 0.84) among individuals ≥20 years old and moderate predictive power (AUC = 0.69) among individuals <20 years old. Decreasing values of DTD were associated with a stepwise increase in the failure rate. A "near-track" lesion with a DTD of <8 mm, particularly in individuals ≥20 years old, may be predictive of failure following arthroscopic Bankart repair. When using the glenoid track concept as the basis for surgical decision-making, clinicians may need to consider the DTD value as a continuous variable to estimate failure instead of using a binary on-track/off-track designation. Prognostic Level III. See Instructions for Authors for a complete description of Levels of Evidence.

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.

Measuring Bone Loss in the Unstable Shoulder: Understanding and Applying the Track Concept.

An interesting international debate has been developed over the past 10 years (the last decade) surrounding the surgical procedure for recurrent anteroinferior instability and a definitive consensus is lacking on the factors which favor one technique over another, especially when bone loss is present (soft tissue vs. bone block). Glenoid bone loss is commonly observed in the shoulder with anterior instability, and it is difficult to evaluate the shape of the glenoid using plain radiograph, therefore, computed tomography or intraoperative observation is recommended for accurate assessment of glenoid bone loss and Hill-Sachs lesion. When we consider the bony defect of the glenoid as a risk factor for surgical failure, it is crucial to take into consideration the features of a concomitant Hill-Sachs lesion. However, all the previous reports focusing on the size of the Hill-Sachs lesion or on the glenoid bone loss in isolation, overlook the interaction of the 2 lesions through the arc of range of motion and how this may influence instability. The glenoid track is the first model to determine, in a dynamic way, how bone loss on both sides of the joint can lead to instability. The glenoid track is a zone of contact created by the glenoid on the humeral articular surface when the arm is moved along the end-range of motion (abduction and external rotation). The use of the glenoid track concept can potentially help guide surgical decision-making.

Évaluation de la cinématique gléno-humérale au moyen d’un modèle numérique d’épaule par éléments finis

BackgroundThe 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. ObjectiveTo evaluate the glenoid track in a finite element numerical model of the shoulder. MethodsWe 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. ResultsThe 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. ConclusionThe 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 evidenceBasic science study; computer modelling.

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

BackgroundThe 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. ObjectiveTo evaluate the glenoid track in a finite element numerical model of the shoulder. MethodsWe 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. ResultsThe 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. ConclusionThe 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 evidenceBasic 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.

Glenoid Track Instability Management Score: Radiographic Modification of the Instability Severity Index Score

The purpose of this study is (1) to test the proposed treatment algorithm, the Glenoid Track Instability Management Score (GTIMS), which incorporates the glenoid track concept into the instability severity index score (ISIS), and (2) to compare treatment decision-making using either GTIMS versus ISIS in 2 cohorts of patients with operatively treated anterior instability. A multicenter, retrospective review of two consecutive groups consisting of 72 and 189 patients treated according to ISIS and GTIMS, respectively, was conducted. Inclusion criteria for all patients were ≥2 confirmed traumatic anterior shoulder instability events and a physical examination demonstrating a positive anterior apprehension and relocation test. The GTIMS was graded for all 189 patients in the cohort, which uses 3-dimensional computed tomography as the sole radiographic parameter to assess on-track (0 points) versus off-track (4 points) Hill-Sachs lesions. This method differs from ISIS, which uses multiple plain radiographs for the 4-point imaging portion of the score. Outcomes scores were compared within the GTIMS and ISIS groups, as well as between them for overall comparisons based on the Western Ontario Shoulder Instability Index (WOSI), the Single Assessment Numerical Evaluation (SANE) score, and the mean rates of recurrent instability. A total of 261 consecutive patients from 2009 to 2014 who presented with recurrent anterior shoulder instability were treated according to either ISIS (n= 72/261, 27.6%) or GTIMS (n= 189/261, 72.4%). At a mean follow-up time of 33.2months (range 24-49months), the overall cohort mean ISIS of 2.9 ± 2.2 (range 0-9) was significantly higher than the mean GTIMS of 1.9 ± 1.9 (range= 0-9, P < .001). Of the 72 ISIS treated patients, 50 (69.4%) had an ISIS score of ≥ 4 and underwent a Latarjet, and the 22 patients (30.6%) with an ISIS score of < 4 underwent an arthroscopic Bankart repair. Based on GTIMS in the 189-patient cohort, using the same cutoff of 4 to indicate the need for a Latarjet, 162 patients were treated with arthroscopic Bankart repair (85.7%) and 27 with Latarjet (14.3%). The overall outcomes improved for patients treated with a Latarjet in both groups (GTIMS WOSI from 1099 [47.7% normal] to 395 [81.3% normal]; GTIMS SANE from 48 to 81; ISIS WOSI from 1050 [50% normal] to 345 [83.4% normal]; ISIS SANE from 50 to 84; P < .01). Similar positive outcomes were seen in patients treated with arthroscopic Bankart repair (GTIMS WOSI from 1062 [49.2% normal] to 402 [80.6% normal]; GTIMS SANE from 49 to 82; ISIS WOSI from 1080 [51.8% normal] to 490 [76.7% normal]; ISIS SANE from 48 to 77; P < .01). Of note, the patients with arthroscopically indicated ISIS had significantly worse outcomes scores than those treated arthroscopically according to GTIMS (P < .01). Of the 189 patients graded with GTIMS, there would have been 33 more Latarjet procedures recommended based on ISIS score. Thus the distribution of procedures based on ISIS versus GTIMS was significantly different (χ2= 45.950; P < .001), indicating a higher rate of recommending Latarjets when using ISIS versus GTIMS. When ISIS scoring and plain radiograph parameters only are used, this predicted a 2-fold increase in recommending a Latarjet versus GTIMS scoring criteria, which uses advanced imaging and the on- and off-track principle to more conservatively delineate anterior instability treatment with promising postoperative patient outcomes. Overall, there were minimal differences in outcomes between GTIMS and ISIS Latarjet patients; however, better outcomes were seen in patients indicated for arthroscopic Bankart repair according to GTIMS and on-off track computed tomography scanning indications. II, Prospective Cohort Study.

Remplissage Procedure: When and How?

Hill-Sachs lesions were first described in 1940 as grooved defect in the posterior aspect of the humeral head associated with traumatic anterior glenohumeral dislocation. The reported incidence of ...

Bipolar Bone Loss And Glenoid Bone Loss Alone are Both Associated with Failure After Arthroscopic Anterior Shoulder Stabilization

Objectives: Glenoid and humeral bone loss are both known risk factors for failure after anterior shoulder stabilization. Several models have previously been proposed to characterize bone loss and its association with recurrent instability. The purpose of this study was to determine the association of failure after arthroscopic anterior stabilization with three different models of shoulder instability. Methods: 128 individuals who underwent primary anterior shoulder stabilization between 2007-2015 were included in this study. Subjects were excluded on the basis of prior shoulder surgery, multidirectional instability, presence of connective tissue disorder, and concomitant rotator cuff pathology. Glenoid bone loss and Hill-Sachs lesion size were measured using previously reported methods. Cases were defined as individuals who sustained either a subluxation or dislocation event after the index procedure, while controls were defined as individuals who did not. The association between failure and three different models of instability were investigated. In the first model, a receiver-operating curve was constructed to determine the amount of glenoid bone loss alone that would best predict failure. In the second model, lesions were classified as on-track or off-track based on the glenoid track concept. In the third model, a distance-to-dislocation was determined based on the glenoid track concept. Combinations of glenoid bone loss and distance-to-dislocation were varied to determine the combination that was most closely associated with failure. T-test, chi-square, and Fisher exact testing was conducted to determine associations between categorical and continuous variables with failure. Results: There were 44 cases and 80 controls. There was no difference in age (p =.72) and sex (p= .69) between the two cohorts. Receiver-operator analysis of glenoid bone loss alone demonstrated that a threshold value of approximately 12% could best predict failure (AOC = 0.72). 21/25 (84%) of individuals with at least 12% bone loss failed surgery compared to 23/103 (22.3%) who had less than 12% bone loss (p &lt; .001). Using the glenoid track model, 4/4 (100%) of individuals with off-track lesions failed surgery compared to 40/124 (32%) with on-track lesions (p &lt; .001). Using a bipolar bone loss model, the combination thresholds of 9% glenoid bone loss and 11 mm distance-to-dislocation was associated with failure in 18/20 (90%) of subjects while 26/108 (24.1%) of subjects who did not meet this threshold failed surgery (p &lt; .001). Intra-rater reliability for glenoid bone loss (ICC = 0.79) and Hill-Sachs lesion size (ICC = 0.75) were excellent. Conclusion: In our study, a threshold value of 12% glenoid bone loss predicted failure following an arthroscopic Bankart repair and all off-track Hill-Sachs lesions failed as well. Further, when both glenoid bone loss and glenoid track were subcritical, the combined use of a bipolar bone loss model accurately predicted failure. This model may be particularly useful for lesions felt to be on the cusp but not beyond threshold values for critical glenoid bone loss and off-track Hill-Sachs defects.

In Vivo Glenoid Track Width Can Be Better Predicted With the Use of Shoulder Horizontal Extension Angle

Background: The glenoid track concept has been widely used to assess the risk of instability caused by a bipolar lesion. The mean glenoid track width is reported to be 83% of the glenoid width. However, this width seems to be affected by the range of motion of the shoulder. By clarifying the relationship between the range of shoulder motion and the glenoid track width, a more precise determination of the glenoid track width for each individual could be possible. Purpose: To determine the relationship between the glenoid track width and the range of motion of healthy volunteers. Study Design: Descriptive laboratory study. Methods: Magnetic resonance imaging was taken in 41 shoulders of 21 healthy volunteers (mean age, 32 years) with the arm in maximum horizontal extension, with the arm kept in 90° of abduction and 90° of external rotation. Three-dimensional surface bone models of the glenoid and the humerus were created with image analysis software. The distance from the anterior rim of the glenoid to the medial margin of the footprint of the rotator cuff tendon was defined as the glenoid track width. Active and passive ranges of shoulder motion were measured in the supine and sitting positions. The correlations between the glenoid track width and the ranges of shoulder motion were investigated with Pearson correlation coefficients. Intra- and interobserver reliabilities based on the intraclass correlation coefficient were also analyzed to assess the reliability of the glenoid track measurement. Results: The intra- and interobserver reliabilities for the glenoid track measurement were excellent (0.988 and 0.988, respectively). Among all the measurements, the glenoid track width and the active range of motion in horizontal extension in the sitting position showed the greatest correlation coefficient (r = −0.623, P < .0001). A correlation between the glenoid track width and this angle was expressed as Y = −0.49X + 90, where X is the horizontal extension angle (degrees) and Y is the glenoid track width (percentage of glenoid width). Conclusion: The present data demonstrate that the greater the horizontal extension angle in abduction and external rotation, the smaller the glenoid track width. An individualized glenoid track width can be obtained by measuring the active horizontal extension angle with the arm in abduction and external rotation in the sitting position. Clinical Relevance: An individualized glenoid track width enables selection of a more precise surgical option by the on-track/off-track concept.

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

BackgroundThe 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.MethodsWe 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.ResultsAmong 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.ConclusionClinical 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.

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

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. Patients who underwent arthroscopic Bankart repair with selective Remplissage procedure for recurrent anterior shoulder instability and were followed up for at least 2years 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. 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). 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. III.

The Glenoid Track and How It Can Guide Management

The classification and treatment of bone loss in anterior shoulder instability remain as significant challenges to the shoulder surgeon, particularly when bipolar lesions are present. The concept of the glenoid track was developed in order to be able to predict whether engagement of a humeral Hill-Sachs lesion (HSL) would occur in the anterior apprehension position of the shoulder. A rational classification system for HSL as “on-track” (nonengaging) or “off-track” (engaging) flowed out of the biomechanical knowledge of the glenoid track. An “on-track, off-track” treatment paradigm has subsequently been described whereby “off-track” HSL are recommended to be treated by arthroscopic remplissage and Bankart repair to restore shoulder stability and prevent engagement. This article contains a discussion of the history, the biomechanics, and the treatment considerations of Hill-Sachs lesions with a focus on bipolar bone loss as informed by the glenoid track.

Glenoid Track Instability Management Score: Radiographic Modification of the Instability Severity Index Score (ISIS)

Although the Instability Severity Score (ISIS) has been traditionally used to predict risk of recurrence following treatment of shoulder instability, the score includes limited radiographic parameters to define bony injuries of the glenohumeral joint. Therefore, the purposes of this study are to (1) To test a new scoring method, termed the "Glenoid Track Instability Management Score (GTIMS)", which incorporates the glenoid track concept into the Instability Severity Index Score (ISIS), (2) compare the GTIMS to ISIS for treatment decision making in a consecutive cohort of patients.