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

BACKGROUND: Current treatment paradigms for anterior shoulder instability are based on radiologic measurements of glenohumeral bone defects, and mathematical calculation of the glenoid track (GT) is used to classify lesions into on-track and off-track morphology. However, radiologic measurements have shown high variability, and GT widths under dynamic conditions have been reported to be significantly smaller than those under static radiologic conditions. The purpose of this study was to assess the reliability, reproducibility, and diagnostic validity of dynamic arthroscopic standardized tracking (DAST) in comparison to the gold-standard radiologic track measurement method for the identification of on- and off-track bony lesions in patients with anteroinferior shoulder instability. METHODS: Between January 2018 and August 2022, 114 patients with traumatic anterior shoulder instability were evaluated using 3-T magnetic resonance imaging or computed tomography scans; glenoid bone loss, Hill-Sachs interval, GT, and Hill-Sachs occupancy ratio (HSO) were measured, and defects were classified as on-track or off-track defects and peripheral-track defects (based on HSO percentage) by 2 independent researchers. During arthroscopy, a standardized method (DAST method) was used by 2 independent observers to classify defects into on-track defects (central and peripheral) and off-track defects. Interobserver reliability of the DAST and radiologic methods was calculated using the κ statistic and reported as percentage agreement. Diagnostic validity (sensitivity, specificity, positive predictive value, and negative predictive value) of the DAST method was calculated using the radiologic track (HSO percentage) as the gold standard. RESULTS: The radiologically measured mean glenoid bone loss percentage, Hill-Sachs interval, and HSO in off-track lesions were lower with the arthroscopic method (DAST) as compared with the radiologic method. The DAST method showed nearly perfect agreement between the 2 observers for the on-track/off-track classification (κ = 0.96, P < .001) and the on-track central or peripheral /off-track classification (κ = 0.88, P < .001). The radiologic method showed greater interobserver variability (κ = 0.31 and κ = 0.24, respectively) with only fair agreement for both classifications. Inter-method agreement varied between 71% and 79% (95% confidence interval, 62%-86%) between the 2 observers, and reliability was assessed as slight (κ = 0.16) to fair (κ = 0.38). Overall, for identification of an off-track lesion, the DAST method showed maximum specificity (81% and 78%) when radiologic peripheral-track lesions (HSO percentage of 75%-100%) were considered off-track and showed maximum sensitivity when arthroscopic peripheral-track lesions were classified as off-track. CONCLUSION: Although inter-method agreement was low, a standardized arthroscopic tracking method (DAST method) showed superior interobserver agreement and reliability for lesion classification in comparison to the radiologic track method. Incorporating DAST into current algorithms may help reduce variability in surgical decision making.

Native Glenoid Depth and Hill-Sachs Lesion Morphology in Traumatic Anterior Shoulder Instability.

BACKGROUND: Although Hill-Sachs lesions (HSLs) are assumed to be influenced by glenoid characteristics in the context of bipolar bone loss, little is known about how glenoid concavity influences HSL morphology. PURPOSE: To investigate the relationship between the native glenoid depth and HSL morphological characteristics. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Computed tomography images of bilateral shoulders from 151 consecutive patients with traumatic unilateral anterior shoulder instability were retrospectively reviewed. Patients were categorized into flat (<1 mm), moderate (1-2 mm), and deep (>2 mm) groups based on the native glenoid depth measured from the contralateral unaffected shoulder. The HSL morphological characteristics included size (depth, width, length, and volume), location (medial, superior, and inferior extent), and orientation (rim and center angle). The glenoid characteristics included diameter, depth, version, and bone loss. The patient, glenoid, and HSL morphological characteristics were compared among the 3 depth groups. Subsequently, the independent predictors of some critical HSL morphological characteristics were determined using multivariate stepwise regression. RESULTS: After exclusion of 55 patients, a total of 96 patients were enrolled and classified into the flat group (n = 31), moderate group (n = 35), and deep group (n = 30). Compared with those in the flat group, patients in the deep group were more likely to have dislocation (38.7% vs 93.3%; P = .009) at the primary instability and had a significantly larger number of dislocations (1.1 ± 1.0 vs 2.2 ± 1.8; P = .010); moreover, patients in the deep group had significantly deeper, wider, larger volume, more medialized HSLs and higher incidences of off-track HSLs (all P≤ .025). No significant differences were detected among the 3 groups in HSL length, vertical position, and orientation (all P≥ .064). After adjustment for various radiological and patient factors in the multivariate regression model, native glenoid depth remained the strongest independent predictor for HSL depth (ß = 0.346; P < .001), width (ß = 0.262; P = .009), volume (ß = 0.331; P = .001), and medialization (ß = -0.297; P = .003). CONCLUSION: The current study sheds light on the association between native glenoid depth and the morphology of HSLs in traumatic anterior shoulder instability. Native glenoid depth was independently and positively associated with HSL depth, width, volume, and medialization. Patients with deeper native glenoids were more likely to have off-track HSLs and thus require more attention in the process of diagnosis and treatment.

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

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

Acute Shoulder Injuries in Adults.

Acute shoulder pain lasting less than six months is a common presentation to the primary care office. Shoulder injuries can involve any of the four shoulder joints, rotator cuff, neurovascular structures, clavicle or humerus fractures, and contiguous anatomy. Most acute shoulder injuries are the result of a fall or direct trauma in contact and collision sports. The most common shoulder pathologies seen in primary care are acromioclavicular and glenohumeral joint disease and rotator cuff injury. It is important to conduct a comprehensive history and physical examination to identify the mechanism of injury, localize the injury, and determine if surgical intervention is needed. Most patients with acute shoulder injuries can be treated conservatively using a sling for comfort and participating in a targeted musculoskeletal rehabilitation program. Surgery may be considered for treating middle third clavicle fractures and type III acromioclavicular sprains in active individuals, first-time glenohumeral dislocation in young athletes, and those with full-thickness rotator cuff tears. Surgery is indicated for types IV, V, and VI acromioclavicular joint injuries or displaced or unstable proximal humerus fractures. Urgent surgical referral is indicated for posterior sternoclavicular dislocations.

Predictors of Bone Loss in Anterior Glenohumeral Instability.

BACKGROUND: Anterior shoulder instability can result in bone loss of both the anterior glenoid and the posterior humerus. Bone loss has been shown to lead to increased failure postoperatively and may necessitate more complex surgical procedures, resulting in worse clinical outcomes and posttraumatic arthritis. HYPOTHESIS/PURPOSE: The purpose of this study was to investigate predictors of glenoid and humeral head bone loss in patients undergoing surgery for anterior shoulder instability. It was hypothesized that male sex, contact sport participation, traumatic dislocation, and higher number of instability events would be associated with greater bone loss. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 892 patients with anterior shoulder instability were prospectively enrolled in the Multicenter Orthopaedic Outcomes Network (MOON) Shoulder Instability cohort. The presence and amount of anterior glenoid bone loss and accompanying Hill-Sachs lesions were quantified. Descriptive information and injury history were used to construct proportional odds models for the presence of any bone defect, for defects >10% of the anterior glenoid or humeral head, and for combined bony defects. RESULTS: Anterior glenoid bone loss and Hill-Sachs lesions were present in 185 (20.7%) and 470 (52.7%) patients, respectively. Having an increased number of dislocations was associated with bone loss in all models. Increasing age, male sex, and non-White race were associated with anterior glenoid bone defects and Hill-Sachs lesions. Contact sport participation was associated with anterior glenoid bone loss, and Shoulder Actitvity Scale with glenoid bone loss >10%. A positive apprehension test was associated with Hill-Sachs lesions. Combined lesions were present in 19.4% of patients, and for every additional shoulder dislocation, the odds of having a combined lesion was 95% higher. CONCLUSION: An increasing number of preoperative shoulder dislocations is the factor most strongly associated with glenoid bone loss, Hill-Sachs lesions, and combined lesions. Early surgical stabilization before recurrence of instability may be the most effective method for preventing progression to clinically significant bone loss. Patients should be made aware of the expected course of shoulder instability, especially in athletes at high risk for recurrence and osseous defects, which may complicate care and worsen outcomes. REGISTRATION: NCT02075775 (ClinicalTrials.gov identifier).

Arthroscopic findings of the glenohumeral joint in symptomatic anterior instabilities: comparison between overhead throwing disorders and traumatic shoulder dislocation.

BACKGROUND: The term shoulder instability refers to a variety of mechanisms and clinical presentations. One of the common pathologies of throwing disorders is internal impingement with anterior instability. Most throwing athletes with symptomatic internal impingement with anterior instability exhibit positive apprehension and relocation test results, whereas those with recurrent anterior shoulder instability display positive apprehension test results. While the glenoid labrum-inferior glenohumeral ligament complex is a significant critical stabilizer for the prevention of anterior shoulder dislocation, the characteristics of the essential lesion in internal impingement with anterior instability have not been determined yet. This study aimed to compare the intra-articular lesion of athletes with internal impingement related to the overhead throwing motion in athletes with a traumatic shoulder dislocation. METHODS: Sixty-one athletes (all men; mean age, 25.2 ± 12.6 yr) who underwent an arthroscopic procedure were divided into 2 groups: 25 in the throwing group and 36 in the dislocation group. All shoulders had subtle glenohumeral instability defined by a positive anterior apprehension test and a relocation test. Those with voluntary and multidirectional instability and large glenoid bone loss (more than 25%) were excluded from the current study. All shoulders were evaluated for the following evidence: rotator cuff injury, superior labrum tear anterior and posterior lesions, labral pathologies including Bankart lesions, osteochondral lesions to the humeral head, biceps tendon fraying or rupture, and inferior glenohumeral ligament and middle glenohumeral ligament (MGHL) conditions. RESULTS: Arthroscopic findings of the throwing group showed more supraspinatus injuries (92% and 25%, P < .001), type II superior labrum tear anterior and posterior lesions (60% and 3%, P < .001), posterosuperior labral lesions (92% and 39%, P < .001), and hypoplastic MGHLs (56% and 6%, P < .001) and lesser Bankart lesions (8% and 92%, P < .05) than those of the dislocation group. CONCLUSIONS: These results indicate that the characteristic lesions of internal impingement with anterior instability in throwing athletes include partial thickness rotator cuff tears, superior labrum tear anterior and posterior lesions, posterosuperior labral tears, and hypoplastic MGHLs. As expected, the physiopathology of internal impingement with anterior instability in throwing athletes may be related to the dysfunction of the anterosuperior glenohumeral capsular ligament, including the MGHL, rather than the inferior glenohumeral ligament as in traumatic anterior shoulder dislocations. These findings would be useful for defining treatment strategies for internal impingement with anterior instability in overhead throwing athletes.

Does reverse total shoulder arthroplasty with allograft-prosthesis composite (APC) have surgical benefits over hemiarthroplasty with APC in patients with tumors of the proximal humerus?

BACKGROUND: The research on surgical outcomes of hemiarthroplasty and reverse total shoulder arthroplasty using allograft-prosthesis composites for the proximal humeral oncologic condition is still scarce. Therefore, this study aimed to compare surgical outcomes of shoulder joint reconstruction with hemiarthroplasty and reverse total shoulder arthroplasty using allograft-prosthesis composites for tumors of the proximal humerus. METHODS: Eleven patients underwent hemiarthroplasty or reverse total shoulder arthroplasty using allograft-prosthesis composites for tumors of the proximal humerus between July 2011 and April 2018 were reviewed. Radiographic analysis for bone union of allograft-host bone junction, implant loosening, stress shielding and shoulder dislocation or subluxation was performed. Functional outcomes were evaluated using visual analog scales for pain, range of motion, Simple Shoulder Test score and Musculoskeletal Tumor Society score. Furthermore, oncologic outcome and complications were also assessed, respectively. RESULTS: There were five patients with hemiarthroplasty (mean age, 23.2 years) and six patients with reverse total shoulder arthroplasty (mean age, 46.8 years, P = 0.05). Radiographically, there were no events associated with implant loosening, stress shielding and shoulder dislocation or subluxation in the two groups. There were no differences in functional outcomes between the two groups. There was no local recurrence in entire cohort. In the hemiarthroplasty group, one patient was required revision surgery to reverse total shoulder arthroplasty at postoperative 6 years due to rotator cuff dysfunction. In the reverse total shoulder arthroplasty group, one patient showed the fracture occurred at allograft-host bone junction at postoperative 6 months. CONCLUSIONS: Surgical outcomes of hemiarthroplasty with allograft-prosthesis composites were not inferior to reverse total shoulder arthroplasty when applied in properly selected patients. The authors recommended that hemiarthroplasty with allograft-prosthesis composites could be used for young age patients without glenoid metastasis involvement, and reverse total shoulder arthroplasty with allograft-prosthesis composites could be used for patients with old age or metastatic bone tumors.

Acromioclavicular dislocation associated with scapular fractures - pathoanatomy of the injury.

INTRODUCTION: No detailed study dealing with an injury to the AC joint in combination with scapular fractures has been published to date. The aim of this study is to describe pathoanatomy of these injuries. METHODS: In a series of 519 scapular fractures in adult patients from the period of 20022020 we identified a total of 20 (3.9%) cases associated with AC dislocation. The group comprised 17 men and 3 women with the mean age of 49 years (range, 2178). Radiographs of the shoulder joint followed by CT examination, including 3D reconstructions, were performed in all patients. This documentation allowed assessment of the scapular fracture pattern and type of injury to the AC joint. RESULTS: AC dislocation was associated with a simple scapular fracture in 15 cases (7 fractures of the coracoid base, 4 fractures of the acromion or the lateral spine, 2 fractures of the scapular body, 1 fracture of the superior and 1 fracture of the inferior glenoid). In 5 cases AC dislocation accompanied multiple or complex scapular fractures (once a combination of a coracoid fracture and a fracture of the lateral scapular spine, once a combination of a fracture of the superior glenoid and of the acromion, 2 cases of a complex intraarticular fracture and 1 case of scapulothoracic dissociation). CONCLUSION: AC dislocation is relatively infrequent injury accompanying scapular fractures. It is most commonly associated with fractures of coracoid, acromion/lateral spine or superior glenoid. No case of AC dislocation was recorded in a fracture of the scapular neck.

Prospective Evaluation of Posterior Glenoid Bone Loss After First-time and Recurrent Posterior Glenohumeral Instability Events.

BACKGROUND: Although posterior glenohumeral instability is becoming an increasingly recognized cause of shoulder pain, the role of posterior glenoid bone loss on outcomes remains incompletely understood. PURPOSES: To prospectively determine the amount of bone loss associated with posterior instability events and to determine predisposing factors based on preinstability imaging. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 1428 shoulders were evaluated prospectively for ≥4 years. At baseline, a subjective history of shoulder instability was ascertained for each patient, and bilateral noncontrast magnetic resonance imaging (MRI) scans of the shoulders were obtained regardless of any reported history of shoulder instability. The cohort was prospectively followed during the study period, and those who were diagnosed with posterior glenohumeral instability were identified. Postinjury MRI scans were obtained and compared with the screening MRI scans. Glenoid version, perfect-circle-based bone loss was measured for each patient's pre- and postinjury MRI scans using previously described methods. RESULTS: Of the 1428 shoulders that were prospectively followed, 10 shoulders sustained a first-time posterior instability event and 3 shoulders sustained a recurrent posterior instability event. At baseline, 11 of 13 shoulders had some amount of glenoid dysplasia and/or bone loss. The change in glenoid bone loss was 5.4% along the axis of greatest loss (95% CI, 3.8%-7.0%; P = .009), 4.4% at the glenoid equator (95% CI, 2.7%-6.2%; P = .016), and 4.2% of total glenoid area (95% CI, 2.9%-5.3%; P = .002). Recurrent glenoid instability was associated with a greater amount of absolute bone loss along the axis of greatest loss compared with first-time instability (recurrent: 16.8% ± 1.1%; 95% CI, 14.6%-18.9%; first-time: 10.0% ± 1.5%; 95% CI, 7.0%-13.0%; P = .005). Baseline glenoid retroversion ≥10° was associated with a significantly greater percentage of bone loss along the axis of greatest loss (≥10° of retroversion: 13.5% ± 2.0%; 95% CI, 9.6%-17.4%; <10° of retroversion: 8.5% ± 0.8%; 95% CI, 7.0%-10.0%; P = .045). CONCLUSIONS: Posterior glenohumeral instability events were associated with glenoid bone loss of 5%. The amount of glenoid bone loss after a recurrent posterior glenohumeral instability event was greater than that after first-time instability. Glenoid retroversion ≥10° was associated with a greater amount of posterior glenoid bone loss after a posterior instability event.

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.

Clinical Outcomes in Patients With Humeral Avulsion Glenohumeral Ligament Lesions in the Setting of Anterior Shoulder Instability: A Retrospective Comparative Study.

BACKGROUND: Humeral avulsion glenohumeral ligament (HAGL) lesions are often underreported but have been shown to occur in up to 10% of cases of anterior shoulder instability. PURPOSE: To compare clinical outcomes and recurrence rates of patients with HAGL lesions undergoing open stabilization for anterior shoulder instability versus a pair-matched control. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective review of all patients who underwent both arthroscopic and open stabilization procedures with a minimum 24-month follow-up was performed. Patients with HAGL lesions were pair-matched in a 1:6 ratio for age, sex, sport, level of preoperative play, and follow-up length with those without HAGL lesions who underwent arthroscopic Bankart repair alone. Return to play (RTP), the level of return, and the timing of return were assessed. In addition, recurrence, visual analog scale for pain (VAS), Subjective Shoulder Value (SSV), Rowe score, satisfaction, and whether they would undergo the same surgery again were compared. RESULTS: A total of 15 patients with HAGL lesions who underwent shoulder stabilization procedures were included, with a mean age of 21.5 ± 4.1 years and mean follow-up of 53.5 ± 17.4 months, and were pair-matched to 90 patients without HAGL lesions. Overall, there was no significant difference in any of the clinical outcome scores (VAS, Rowe, SSV, satisfaction) used between the 2 groups (1.6 vs 1.7, P = .86; 83.4 vs 88.0, P = .06; 85.7 vs 87.2, P = .76; and 86.7% vs 94.5%, P = .26, respectively). In addition, there were no significant differences in terms of overall rates, levels, and timing of RTP between the 2 groups (93.3% vs 90.0%, P > .99; 80.0% vs 78.9%, P > .99; and 5.3 ± 2.2 vs 5.9 ± 2.9 months, P = .45, respectively). There was no significant difference in the rates of apprehension, subluxation, and recurrent instability between the HAGL and pair-matched control groups (26.7% vs 26.7%, P > .99; 6.7% vs 3.3%, P = .47; and 13.3% vs 6.7% months, P = .32, respectively). CONCLUSION: Patients with anterior shoulder instability undergoing surgical stabilization with open HAGL repair demonstrate excellent functional outcomes and high rates of RTP, with low rates of recurrence in the medium term compared with a control group without HAGL lesions who underwent arthroscopic Bankart repair alone.

In-Season Management of Anterior Shoulder Instability.

Anterior shoulder instability commonly occurs in young and active individuals, particularly those participating in contact or collision sports. At the intercollegiate level, rates of anterior instability have been reported to be 0.12 events per 1000 athlete exposures. The treatment of in-season athletes with anterior instability presents a challenge for the team physician. The desire to return to play within the same season with nonoperative management must be weighed against the increased risk of recurrence as well as athlete and team specific demands. The purpose of this chapter is to discuss the key considerations for the management of the athlete with anterior shoulder instability that occurs within the competitive season.

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.

Chapter 6: Attritional Glenoid Bone Loss in the Shoulder: Operative Considerations.

Patients with recurrent anterior shoulder instability often have glenoid bone loss present in addition to soft tissue pathologies. It is known that patients with significant glenoid bone loss are best treated with a boney augmentation procedure as opposed to a soft tissue Bankart repair because of the high rate of recurrent instability that results from a Bankart repair. Although the Latarjet technique has been the gold-standard treatment for patients with glenoid bone loss because of the low incidence of recurrent instability, it has a high complication rate and a steep learning curve. Herein, the authors present the technique and outcomes for arthroscopic anatomic glenoid reconstruction that has a similar complication rate to the Bankart repair but with a low recurrence rate similar to the Latarjet. This procedure is safe, has a short learning curve, low recurrence rate, and positive patient-reported outcomes.

Bilateral Erecta Luxation: A Case Report and Literature Review.

CASE: A 69-year-old man fell from a height, resulting in direct axial loading while both shoulders were fully abducted. He was referred to the surgical ward, and both shoulders were reduced by closed reduction using the traction-countertraction maneuver. After little improvement of complaints of pain in the right shoulder over 45 days, magnetic resonance demonstrated traumatic rupture of the supraspinatus. CONCLUSION: Inferior dislocation (luxation erecta) is an uncommon event, with bilateral dislocation being even rarer. Treatment should be initiated urgently via closed reduction or, if this is not possible, through open reduction. The long-term prognosis is favorable after appropriate treatment.

Mechanism and patterns of bone loss in patients with anterior shoulder dislocation.

BACKGROUND: Bony defects are common injuries associated with anterior shoulder dislocation. It is generally thought that these bony defects are created at the time of dislocation. However, there have been no biomechanical reports demonstrating the exact time point when these lesions occur. The purpose of this study was to clarify when, how, and which types of bony defects were created during experimental dislocation in cadaveric shoulders. METHODS: Fifteen fresh-frozen cadaveric shoulders (mean age at the time of death, 79 years) were fixed in a custom testing machine. First, the glenohumeral joint was inspected by arthroscopy. Then, the arm was held at 60° of abduction and maximum external rotation and was manually extended horizontally under fluoroscopy until an anterior dislocation occurred. Next, a force of 800 N was applied to a Kirschner wire inserted in the humeral head in the direction of the pectoralis major with use of an air cylinder. We waited until the arm came to equilibrium under this condition. Finally, the glenohumeral joint was arthroscopically examined. We further performed x-ray micro-computed tomography and histologic examination in 1 shoulder with a bipolar lesion. RESULTS: After the anterior dislocation, a Bankart lesion was created in 9 of 15 shoulders and a fragment-type glenoid defect (avulsion fracture) was created in 4. A Hill-Sachs lesion, on the other hand, was not observed after the dislocation. The equilibrium arm position was 40° ± 17° in flexion, 45° ± 22° in abduction, and 27° ± 19° in external rotation. In this arm position, newly created lesions were Hill-Sachs lesions in 6 shoulders and erosion-type glenoid defects (compression fracture) in 7. Micro-computed tomography, performed in a single specimen, showed a flattened anterior glenoid rim with collapse of trabecular bone. Histologic analysis of nondecalcified sections using hematoxylin-eosin staining indicated that the anterior rim of the glenoid was compressed and flattened. The cortex of the anterior glenoid rim could be clearly observed. CONCLUSION: The fragment-type glenoid defect (avulsion fracture) was observed at the time of dislocation, whereas the erosion-type defect (compression fracture) was observed when the arm came to equilibrium in the midrange of motion. Hill-Sachs lesions were created not at the time of dislocation but after the arm came to equilibrium.

Influence of coracoid anatomy on the location of glenoid rim defects in anterior shoulder instability: 3D CT-scan evaluation of 51 patients.

PURPOSE: Glenoid bony lesions play a role in approximately half of anterior shoulder instability cases. The purpose of this study is to see if the anatomy of the coracoid affects the location of glenoid rim defects. We hypothesized that a prominent coracoid (lower and lateral) would be more likely to cause an anterior-inferior glenoid lesion, and a less prominent coracoid more prone to cause an anterior lesion. The null hypothesis being the absence of correlation. METHODS: Fifty-one shoulder CT-scans from a prospective database, with 3D reconstruction, were analyzed. The position of glenoid lesions was identified using the validated clock method, identifying the beginning and end time. The size of bony glenoid defects was calculated using the validated glenoid ratio method. The position of the coracoid tip was measured in three orthogonal planes. RESULTS: Analysis included 25 right shoulders and 26 left shoulders in seven females and 41 males. The vertical position of the coracoid tip relative to the top of the glenoid was highly correlated to the location of the glenoid defect on the profile view (r = -0.625; 95% CI 0.423-0.768; p = 0.001). Thus, higher coracoids were associated with anterior lesions, while lower coracoids were associated with anterior-inferior lesions. A more laterally prominent coracoid was also correlated with anterior-inferior lesions (r = 0.433; 95% CI 0.179-0.633; p = 0.002). CONCLUSION: This study shows that coracoid anatomy affects the location of bony Bankart defects in anterior shoulder instability. Lower and laterally prominent coracoids are associated with anterior-inferior lesions. This variation in anatomy should be considered during pre-op planning for surgeries involving bone graft. LEVEL OF EVIDENCE: Level 4 basic science.

Surgical treatment of acute Rockwood III acromioclavicular dislocations-Comparative study between two flip-button techniques.

Acromioclavicular joint dislocation is a common shoulder injury, usually caused by direct violence on the shoulder. Optimal treatment of type III is still a hot discussion currently in orthopedic surgeons. With the advent of many flip-button techniques, Tightrope system and Endobutton system become popular techniques for reconstruction of coracoclavicular ligaments. The purpose of the study was to compare the clinical and radiological results between the two techniques. A retrospective case-control study was conducted in 60 patients with acute Rockwood III acromioclavicular joint dislocation. The two techniques conducted were open procedures using Twin Tail Tightrope system (Group A, n = 30) and Endobutton system (Group B, n = 30). 60 patients were followed up at least two years. Surgical parameters including incision length, operation time and operative blood loss were analyzed. Functional outcomes were evaluated using the Constant-Murley Score. Radiological results were assessed based on coracoclavicular distance preoperatively, one day postoperatively, and at the final follow-up. 60 patients were followed up for at least 24 months (range 24 to 32). The incision length and operation time were shorter in Group A than that in Group B. The blood loss of surgery was significantly less in the Group A. There were no significant differences between the two groups regarding the Constant-Murley Score at the final follow-up. No significant differences were found in the coracoclavicular distance preoperatively, immediately postoperatively, and at the final follow-up. Both techniques offered satisfying functional outcomes, however the Tightrope system provided better surgical parameters.

Return to sports after glenoid reconstruction using an implant-free iliac crest bone graft.

PURPOSE: The purpose of this study was to evaluate sports ability and the rate of return to sports after implant-free iliac bone graft for recurrent, anterior shoulder instability and anterior glenoid bone loss. Subgroups of younger and older patients and patients who had previous arthroscopic Bankart surgery and those who did not have such surgery before implant-free iliac bone graft were formed and compared. METHODS: We retrospectively analyzed 34 patients; 14 patients had previous arthroscopic Bankart surgery, and 20 patients did not have the surgery; The median age at the time of iliac bone graft was 35.3 years (range, 23 to 75), 17 patients were over the age of 35, and 17 patients were under the age of 35. The mean follow-up was 40 months (range: 25 to 56). RESULTS: All the 34 patients were engaged in pre- and post-operative sport, which represents a return to sport rate of 100%. Although the number of sport disciplines decreased significantly from 6 before the operation to 4.8 after the operation (p=0.002), the number of sports sessions per week did not change significantly, and the duration per session did not change significantly. More than two-thirds of all patients returned to sports within 6 months. Overall, 41% of patients changed sport disciplines, 15% of whom cited shoulder-related causes; however, all patients returned to the same sport level. CONCLUSIONS: Overall and within the subgroups, the return to sport rate after implant-free iliac bone grafting was high, with a high sense of well-being. The number of sport disciplines decreased significantly and more than one-third of the patients changed disciplines, of which 15% percent changed due to shoulder-related causes. The sport level remained equal, and no other parameters changed significantly compared with the time before the onset of restrictive shoulder symptoms.

Effect of subcritical glenoid bone loss on activities of daily living in patients with anterior shoulder instability.

BACKGROUND: It has been biomechanically demonstrated that 20% to 25% is a critical glenoid bone loss. Recently, there are several reports describing that a bone loss less than 20% to 25% needed to be treated because patients may have decreased quality of life without recurrent instability events. The purpose of this study was to clarify the presence of subcritical bone loss that would affect postoperative instability or quality of life. METHODS: Subjects were 43 patients aged≤40years with less than 25% glenoid bone loss who had undergone arthroscopic Bankart repair. These patients were assessed at a mean follow-up of 32months. The Western Ontario Shoulder Instability (WOSI) and Rowe scores were used for the clinical evaluation. Patients were divided in 3 groups based on the percentage of bone loss: group 1: <8%; group 2: 8% to 17%; and group 3: >17%. RESULTS: The recurrence rate was 7% (3/43 shoulders). A weak negative correlation was seen between bone loss and sports/recreation/work domain of the WOSI score (r=-0.304, p=0.0191). The WOSI for group 3 was significantly lower than that for group 1 and 2 (p=0.0009). The male WOSI scores were significantly lower than the female ones (p=0.0471). The WOSI scores of the contact athletes were significantly lower than those of non-contact athletes (p=0.0275). All the patients in Group 3 were males and participated in contact sports. CONCLUSION: Glenoid bone loss between 17% and 25% is considered to be a "subcritical bone loss" in our series, especially in male patients who are involved in sports or high-level activities. LEVEL OF EVIDENCE: III, retrospective study.