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.

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.

Bipolar bone defect in the shoulder anterior dislocation.

In the anterior shoulder instability with glenoid bone loss among 25 % or more of the inferior glenoid diameter (inverted-pear glenoid), the consensus of recent authors is that glenoid bone grafting (Latarjet procedure) should be performed. The engaging Hill-Sachs lesion has been recognized as a risk factor for recurrent anterior shoulder instability. We have developed a method using radiographic and arthroscopic studies and the concept of the glenoid track to determine whether a Hill-Sachs lesion will engage the anterior glenoid rim, whether or not there is concomitant anterior glenoid bone loss. If the Hill-Sachs lesion engages, it is called an "off-track" Hill-Sachs lesion; if it does not engage, it is an "on-track" lesion. On the basis of our quantitative method, we have developed a treatment paradigm with specific surgical criteria for all patients with anterior shoulder instability (first dislocation or recurrent dislocation), both with and without bipolar bone loss.

Glenohumeral translation in ABER position during muscle activity in patients treated with Latarjet procedure: an in vivo MRI study.

PURPOSE: The Latarjet procedure is frequently performed when treating traumatic anteroinferior shoulder instability. This procedure is supposed to have a triple effect: osseous, muscular and ligamentous. The main stabilizing mechanism in cadaver studies on fresh-frozen shoulders seems to be the sling effect produced by the subscapularis and the conjoint tendon. It has been hypothesized that muscle contraction in ABER position (abduction-external rotation) is able to translate the humeral head posteriorly and superiorly due to the sling effect. The aim of this study was to analyse the humeral head translation relative to the glenoid with the arm in ABER position with and without muscle contraction. METHODS: Twenty-one subjects divided into two groups (Group A: after Latarjet; Group B: healthy subjects) were examined with an open MRI system with the shoulder in abduction-external rotation (ABER) position to analyse humeral head translation during muscle activity. RESULTS: In normal shoulders, there was no significant difference in anteroposterior or superoinferior translation between the rest position and the muscle-activated state. In subjects after the Latarjet procedure, the difference was significant and was also significant between both groups of subjects for posterior translation, but not for superior translation. CONCLUSION: In patients treated with Latarjet procedure, there are significant changes in glenohumeral translation during muscular activity when in ABER position, with the humeral head going more posteriorly, in comparison with normal shoulders. This study confirms the stabilizing sling effect of the transposed conjoint tendon in the ABER position. LEVEL OF EVIDENCE: Retrospective case-control study, Level III.

Does the presence of glenoid bone loss influence coracoid bone graft osteolysis after the Latarjet procedure? A computed tomography scan study in 2 groups of patients with and without glenoid bone loss.

BACKGROUND: Coracoid bone graft osteolysis and fibrous union are the principal causes of failure in patients treated with the Latarjet procedure. This study aims to investigate the hypothesis that coracoid bone graft osteolysis is more pronounced in cases without glenoid bone loss, which may be due to a diminished mechanotransduction effect at the bone healing site. METHODS: We prospectively followed up 34 patients, treated with a mini-plate Latarjet procedure, divided into 2 groups (group A patients had glenoid bone loss >15% and group B patients had no glenoid bone loss). A computed tomography scan evaluation with 3-dimensional reconstruction was then performed on all patients to evaluate coracoid bone graft osteolysis according to our coracoid bone graft osteolysis classification. RESULTS: The computed tomography scan analysis showed a different distribution of osteolysis between group A and group B. The statistical analysis showed a significant difference (P < .01, Bonferroni test) between groups A and B for the following sections: proximal/lateral/superficial, proximal/medial/deep, distal/lateral/superficial, and distal/lateral/deep. On average, the coracoid grafts in group A patients showed less osteolysis than the coracoid grafts in group B patients (39.6% vs 65.1%). DISCUSSION: The coracoid bone graft underwent much less osteolysis in patients with significant glenoid bone loss (>15%) than in those without it. Because factors of blood supply, compression, and surgical technique were the same for both groups, we believe that the mechanotransduction effect from the humeral head on the graft influences its remodeling. CONCLUSION: The results of this study suggest that the bone graft part of the Latarjet procedure plays a role in patients with significant coracoid bone loss but much less so when there is no bone loss.

Management of humeral head deficiencies and glenoid track.

When considering the management of shoulder anterior instability with glenoid bone loss ≥25 % of the inferior glenoid diameter (inverted-pear glenoid), the consensus among recent authors is that glenoid bone grafting should be done. Although the engaging Hill-Sachs lesion has been recognized as a risk factor for recurrent anterior instability, there has been no generally accepted methodology for quantifying the Hill-Sachs lesion taking into account the geometric interplay of various sizes and various orientations of bipolar (humeral-sided plus glenoid-sided) bone loss. Keeping the glenoid track concept in mind, if a Hill-Sachs lesion engages the anterior glenoid rim, with or without concomitant anterior glenoid bone loss, it is possible to manage this pathology, reducing the risk of recurrent shoulder instability after surgery. If the Hill-Sachs engages, "Remplissage" or "Latarjet" surgical procedures are indicated depending of glenoid bone loss.

Coracoid bone graft osteolysis after Latarjet procedure: A comparison study between two screws standard technique vs mini-plate fixation.

AIMS: One of the reason for Latarjet procedure failure may be coracoid graft osteolysis. In this study, we aimed to understand if a better compression between the coracoid process and the glenoid, using a mini-plate fixation during the Latarjet procedure, could reduce the amount of coracoid graft osteolysis. MATERIALS AND METHODS: A computed tomography scan analysis of 26 prospectively followed-up patients was conducted after modified Latarjet procedure using mini-plate fixation technique to determine both the location and the amount of coracoid graft osteolysis in them. We then compared our current results with results from that of our previous study without using mini-plate fixation to determine if there is any statistical significant difference in terms of corcacoid bone graft osteolysis between the two surgical techniques. RESULTS: The most relevant osteolysis was represented by the superficial part of the proximal coracoid, whereas the deep part of the proximal coracoid graft is least involved in osteolysis and has best bone healing. The current study showed a significant difference only for the deep part of the distal coracoid with our previous study (P < 0.01). DISCUSSION: To our knowledge, there are no studies in literature that show the causes of coracoid bone graft osteolysis after Latarjet procedure. CONCLUSION: Our study suggests that there is a significant difference only for the deep part of the distal coracoid in terms of osteolysis. At clinical examination, this difference did not correspond with any clinical findings. LEVEL OF EVIDENCE: Level 4. CLINICAL RELEVANCE: Prospective case series, Treatment study.

Coracoid graft osteolysis after the Latarjet procedure for anteroinferior shoulder instability: a computed tomography scan study of twenty-six patients.

BACKGROUND: The Latarjet procedure has been advocated as an option for the treatment of anteroinferior shoulder instability in certain patients. However, progression of the transferred coracoid bone graft to osteolysis has been reported in the literature. We propose that the coracoid bone graft osteolysis could be one of the causes of failure of the Latarjet procedure. MATERIALS AND METHODS: A computed tomography scan analysis was done of 26 patients prospectively followed-up after the Latarjet procedure to determine the location and the amount of the coracoid graft osteolysis. RESULTS: The most relevant osteolysis was represented by the superficial part of the proximal coracoid, whereas the distal region of the coracoid bone graft, especially in the deep portion, was the least involved in osteolysis and had the best bone healing. DISCUSSION: To our knowledge, this is the first study to quantify and localize coracoid osteolysis after Latarjet procedure for anteroinferior shoulder instability using CT scan analysis. CONCLUSION: Our study suggests that the bone-block effect from the Latarjet procedure may not be the principal effect in its treatment of anteroinferior shoulder instability in patients without significant bony defects.