Rate of Successful Shoulder Reduction on First Confirmatory Imaging in the Emergency Department.

BACKGROUND: Management of acute shoulder dislocation in the emergency department (ED) is common. OBJECTIVE: This study describes the rate, risk factors, and length of stay (LOS) associated with shoulder dislocation reduction failure in the ED. METHODS: The study was a retrospective case-control study of patients 18 years and older presenting to the ED with acute shoulder dislocation who underwent attempted reduction. Patients with successful reduction on post-reduction first confirmatory imaging are compared with those requiring multiple attempts. RESULTS: Of 398 ED encounters when a shoulder reduction was attempted in the ED, 18.8% (75/398 [95% CI 15.2-22.9%]) required multiple reduction attempts. Patients with successful reduction on first confirmatory imaging were more commonly male (80.2% [95% CI 75.6-84.3%] vs. 68.0% [95% CI 56.8-77.8%]; p = 0.0220), discharged home from the ED (95.4% [95% CI 92.6-97.3%] vs. 84.0% [95% CI 74.4-91.0%]; p = 0.0004), reduced using a traction/countertraction technique (42.1% [95% CI 36.8-47.6%] vs. 29.3% [95% CI 19.9-40.4%]; p = 0.0415), and less likely to have a pre-reduction fracture (26.0% [95% CI 21.4-31.0%] vs. 45.3% [95% CI 34.4-56.7%]; p = 0.0010). Mean length of stay (LOS) for those with successful reduction on first confirmatory imaging was 2 hours and 8 minutes shorter than for those with more than one attempt (p < 0.001). CONCLUSIONS: The rate of failed first-pass reduction is higher than previously reported. Furthermore, the ED LOS was significantly longer in patients requiring multiple attempts. Knowledge of the failure rate and risk factors may raise physician awareness and guide future studies evaluating approaches for verification of reduction success.

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.

Efficacy and safety of the Latarjet procedure for the treatment of athletes with glenoid bone defects ≥ 20%: a single-arm meta-analysis.

BACKGROUND: The shoulder joint is the most commonly dislocated joint in the human body, and the recurrence rate exceeds 50% after nonsurgical treatment. Although surgical treatment reduces the recurrence rate, there is controversy regarding the optimal surgical approach. Previous studies suggest that the Latarjet procedure yields favourable outcomes for specific populations at risk of recurrence, such as competitive athletes with significant glenoid defects. However, most of the existing related research consists of nonrandomized controlled trials with small sample sizes, and there is a lack of strong evidence regarding the efficacy and safety of the Latarjet procedure. METHODS: The PubMed, Embase, Cochrane Library, and Web of Science databases were systematically searched. Athletes with ≥ 20% glenoid defects were selected for inclusion. The following data were extracted: general patient information, instability rates, return to sports (RTS) rates, imaging features (graft positioning rate and graft healing rate), functional assessments [Rowe score, Athletic Shoulder Outcome Scoring System(ASOSS), visual analogue scale (VAS), forward flexion function, and external rotation function], and complications. RESULTS: After excluding suspected duplicate cases, a total of 5 studies were included in this meta-analysis. The studies involved a total of 255 patients, including 237 males (93%) and 18 females (7%). The average age at the time of surgery was 25.4 ± 8.5 years. All the studies had a minimum follow-up period of 2 years, with an average follow-up time of 48.7 ± 18.9 months. The pooled rate of return to sport (RTS) was 94.3% (95% CI: 87.3%, 98.8%), and 86.1% (95% CI: 78.2%, 92.5%) of patients returned to their preoperative level of activity. The pooled redislocation rate was 1.1% (95% CI: 0%, 3.8%). Regarding the imaging results, the combined graft retention rate was 92.1% (95% CI: 88.1%, 95.5%), and the graft healing rate was 92.1% (95% CI: 88%, 95.4%). Postoperative functional evaluation revealed that the combined Rowe score, ASOSS score, and VAS score were 93.7 ± 6.5 points, 88.5 ± 4.4 points, and 1.1 ± 10 points, respectively. The forward flexion and external rotation angles were 170.9 ± 6.9 degrees and 65.6 ± 4.5 degrees, respectively. After excluding one study with unclear complications, the combined complication rate was 9.4% (95% CI: 1.0%, 23.6%). CONCLUSION: For athletes with shoulder instability and a total of ≥ 20% glenoid bone defects, the Latarjet procedure can achieve excellent functional outcomes, with the majority of patients returning to preoperative levels of sports activity. This procedure also leads to a low recurrence rate. Therefore, the Latarjet procedure has been proven to be a safe and effective treatment.

Reconstruction of recurrent shoulder dislocation with glenoid bone defect with 3D-printed titanium alloy pad: outcomes at 2-year minimum follow-up.

BACKGROUND: To evaluate the outcome of shoulder arthroscopy-assisted implantation of three-dimensional (3D)-printed titanium pads for recurrent shoulder dislocation with glenoid bone defects. METHODS: From June 2019 to May 2020, the clinical efficacy of 3D printed titanium pad implantation assisted by shoulder arthroscopy, for the treatment of recurrent shoulder dislocations with shoulder glenoid defects was retrospectively analyzed. The American Shoulder and Elbow Surgeons (ASES) shoulder, Rowe, and Constant scores were recorded before surgery and at 3 months, 6 months, 1 year, and 2 years after surgery. 3D computed tomography (CT) and magnetic resonance imaging were used to evaluate the location of the glenoid pad, bone ingrowth, joint degeneration, and osteochondral damage. RESULTS: The mean age of the 12 patients was 21.4 (19-24) years and the mean follow-up time was 27.6 (24-35) months. The Visual Analog Scale score significantly improved from 5.67 ± 1.98 preoperatively to 0.83 ± 0.58 postoperatively (p = 0.012). The postoperative ASES score was significantly increased to 87.91 ± 3.47 compared with preoperative ASES score (46.79 ± 6.45) (p < 0.01). Rowe and Constant scores also improved from 22.5 ± 12.34 and 56.58 ± 7.59 preoperatively to 90.83 ± 4.69 and 90.17 ± 1.89 at 2 years postoperatively, respectively. CT performed 2 years after surgery showed that the pad perfectly replenished the bone-defective part of the shoulder glenoid and restored the articular surface curvature of the shoulder glenoid in the anterior-posterior direction, and the bone around the central riser of the pad was tightly united. Magnetic resonance imaging 2 years after surgery showed that the humeral head osteochondral bone was intact, and there was no obvious osteochondral damage. CONCLUSIONS: 3D printed titanium pads are a reliable, safe, and effective surgical procedure for treating recurrent shoulder dislocations with glenoid bone defects.

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.

[Imaging of posttraumatic shoulder instability : Current concepts]. / Bildgebung bei posttraumatischen Instabilitäten der Schulter : Aktuelle Konzepte.

Posttraumatic instability accounts for more than 95% of all shoulder instabilities with the highest incidence in patients between 20 and 30 years of age. In this age group, lesions of the capsulolabral complex are the most common sequelae after the first shoulder dislocation. Typical acute findings are the Bankart and Perthes lesions and humeral avulsion of the glenohumeral ligament (HAGL). Chronic sequelae are anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesions, and nonclassifiable lesions with deficient anterioinferior labrum and glenohumeral ligaments. Recently, quantification of Hill-Sachs and bony Bankart lesions with glenoid defects have become the focus of interest: bipolar bone loss has emerged to be one important factor of recurrent instability that has not been addressed during the first stabilizing operation. The glenoid track concept emphasizes the importance of bipolar bone loss, where the glenoid track refers to the contact area between the humeral head and the glenoid at the end-range of motion in abduction, extension and external rotation. Any lesion of the humeral head that extends beyond the glenoid track is considered high risk for engagement of the humeral head at the glenoid margin with subsequent dislocation. Both the Hill-Sachs interval and the glenoid track can be determined using computed tomography (CT) and magnetic resonance imaging and, thus, help to define the status of the shoulder (on-track vs. off-track), which is prerequisite for planning the appropriate operative procedure. Similar tendencies also exist for posttraumatic posterior instabilities which are much rarer.

Missed Osteochondral Shear Injury of the Humeral Head Following Anterior Shoulder Dislocation - A Case Report.

CASE: Two months after anterior shoulder dislocation and spontaneous reduction, a 41-year-old man presented movement-related shoulder pain and a functional deficit. An initially missed osteochondral shearing injury of the humeral head with a Bankart lesion was diagnosed. Due to an extensive posteroinferior defect, an open reduction and internal fixation (ORIF) using bioabsorbable chondral darts was performed. At the 1-year follow-up, magnetic resonance images showed a completely healed osteochondral fragment and the patient presented an unrestricted shoulder function. CONCLUSION: Even in missed osteochondral shear injuries, ORIF with bioabsorbable implants can be associated with an excellent functional outcome and sufficient integrity of the fragment. The absorbable implants are biocompatible, therefore the risk of revision surgery due to implant irritations is minimized.

Latarjet in women for anterior shoulder instability: a case series analysis.

PURPOSE: The Latarjet procedure is traditionally used to treat chronic anterior shoulder instability associated with glenoid bone loss. However, few series have analyzed outcomes in a female-only population. The objective of this study was to evaluate the clinical and radiological outcomes of a Latarjet bone block in this specific population. METHODS: This single-center retrospective study included 15 women (mean age 35 ± 11.3; 19-60) reviewed with a minimum follow-up of 2 years. The procedure was performed using the open bone block screw technique (n = 7) or by arthroscopy with cortical button (n = 8). Clinical evaluation was based on active range of motion measurements, Rowe and Walch-Duplay scores, and subjective shoulder value (SSV). Radiographic analysis explored bone block healing at the last follow-up. RESULTS: At a mean follow-up of 48 months (32-86), no recurrence was reported. The mean Rowe score was 91 points (70-100), Walch-Duplay 90 points (60-100), and SSV 87% (70-100). The active mobilities reached 169° (± 9°) in elevation, 57° (± 15°) in external rotation at side, and 89° (± 6°) in abduction. The return-to-sport rate was 91%. Five patients experienced persistent anterior pain, with screws requiring hardware removal in 2 (p = 0.02). Radiological assessment detected one case of nonunion (7%). CONCLUSION: Women treated with the Latarjet procedure experienced satisfactory midterm clinical outcomes. The arthroscopic technique using cortical button fixation seems to avoid residual anterior pain requiring hardware removal.

Automated quantification of glenoid bone loss in CT scans for shoulder dislocation surgery planning.

PURPOSE: Estimation of glenoid bone loss in CT scans following shoulder dislocation is required to determine the type of surgery needed to restore shoulder stability. This paper presents a novel automatic method for the computation of glenoid bone loss in CT scans. METHODS: The model-based method is a pipeline that consists of four steps: (1) computation of an oblique plane in the CT scan that best matches the glenoid face orientation; (2) selection of the glenoid oblique CT slice; (3) computation of the circle that best fits the posteroinferior glenoid contour; (4) quantification of the glenoid bone loss. The best-fit circle is computed with newly defined Glenoid Clock Circle Constraints. RESULTS: The pipeline and each of its steps were evaluated on 51 shoulder CT scans (44 patients). Ground truth oblique slice, best-fit circle, and glenoid bone loss measurements were obtained manually from three clinicians. The full pipeline yielded a mean absolute error (%) for the bone loss deficiency of 2.3 ± 2.9 mm (4.67 ± 3.32%). The mean oblique CT slice selection difference was 1.42 ± 1.32 slices, above the observer variability of 1.74 ± 1.82 slices. The glenoid bone loss deficiency measure (%) on the ground truth oblique glenoid CT slice has a mean average error of 0.54 ± 1.03 mm (4.76 ± 3.00%), close to the observer variability of 0.93 ± 1.40 mm (2.98 ± 4.97%). CONCLUSION: Our pipeline is the first fully automatic method for the quantitative analysis of glenoid bone loss in CT scans. The computed glenoid bone loss report may assist orthopedists in selecting and planning surgical shoulder dislocation procedures.

The arthroscopic double-button Latarjet does not modify the static posterior translation of the humeral head.

INTRODUCTION: The Latarjet procedure treats anterior instability of the shoulder and is based on a triple anterior lock, where the conjoint tendon straps the lower third of the subscapularis muscle. Excessive posterior translation of the humeral head is a known risk factor for shoulder osteoarthritis. No in vivo study has investigated the effect of the bone block on the posterior static translation of the humeral epiphysis. The purpose of this study was to evaluate the effect of the bone block on the static posterior translation of the humeral head. The hypothesis was that this procedure increased this translation. MATERIALS AND METHODS: This retrospective study included patients treated arthroscopically for anterior shoulder instability by a double-button Latarjet. An independent examiner analyzed the CT scans preoperatively, at 15 days, and at least 6 months postoperatively according to a standardized protocol. The analysis focused on the position of the bone block in the axial and coronal planes relative to the glenoid. The posterior translation was automatically calculated using the Blueprint© planning software. RESULTS: Thirty-five patients were included with a mean age of 25 years (16-43), according to a 4M/1F sex ratio. The graft was perfectly flush to the subchondral bone in 63% (n=22) of cases and subequatorial in 91% (n=32). Preoperative posterior humeral translation was 52%. The mean immediate postoperative posterior humeral translation was 56%, and 57% at more than 6 months. The change in mean posterior humeral translation between preoperative/6 months was +0.94% [-20%; +12%] (p=0.29) and immediate postoperative/6 months +0.34% [-18%; +15%] (p=0.84). Gender, hypermobility and the axial position of the bone block did not influence the change in posterior humeral translation. The equatorial position of the bone block appeared to increase posterior humeral translation by +10%±5.2% [-0.427; 20.823] (p=0.07). CONCLUSION: This work refutes our initial hypothesis. The change in static posterior humeral translation after arthroscopic Latarjet bone block remains stable at more than 6 months of follow-up. This procedure does not alter the anatomical position of the humeral head in relation to the glenoid. On the other hand, a more cranial positioning of the bone block could have an influence. LEVEL OF EVIDENCE: IV.

Posterolateral dislocation and incarceration of the long head of the biceps tendon: a rare cause of irreducible anterior glenohumeral joint dislocation-a case report and brief review of the literature.

Failure of closed reduction of anterior glenohumeral joint dislocation is infrequent. It can be secondary to osseous (e.g., fracture fragments or Hill-Sachs lesion) or soft tissue (e.g., labrum or rotator cuff tendon) impediments. Herein, we present a case of a prolonged irreducible glenohumeral joint secondary to a posterolaterally dislocated and incarcerated long head of the biceps tendon after an episode of anterior instability, highlight the utility of MR imaging for guiding management, and review the literature of this sporadic diagnosis.

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.

Humeral Head Reconstruction of Reverse Hill-Sachs Lesions.

Compared with anterior instability, posterior shoulder dislocations are a rare entity and are often missed at presentation. A concomitant anteromedial impression fracture of the humeral head, or a reverse Hill-Sachs lesion, is commonly present with these dislocations and is more pronounced with a longer timeline to reduction. Treatment of these defects ranges from nonsurgical treatment to soft-tissue procedures, bony reconstruction, and arthroplasty. Management may be dictated by various factors, such as patient demands, defect size and location, concomitant injuries, and underlying etiology. Small reverse Hill-Sachs defects without engagement can generally be treated nonsurgically or with benign neglect, whereas larger defects (>20%) often require surgery. The most reported surgical techniques are the (arthroscopic) McLaughlin and modified McLaughlin procedure, disimpaction and bone grafting, or reconstruction of the defect with autograft or with fresh (or fresh-frozen) osteochondral allograft. Finally, arthroplasty is generally required for large defects, where more than 45% to 50% of the articular cartilage is involved. Overall, reported outcomes generally reflect patient satisfaction for most patients, with a low incidence of secondary instability or posttraumatic arthritis, although better results are achieved when recognizing and treating these injuries in the more acute setting.

[Problems of expert application of «Medical criteria to determine the severity of harm caused to human health¼ in closed injury of the shoulder joint]. / Problemy ekspertnogo primeneniya «Meditsinskikh kriteriev opredeleniya stepeni tyazhesti vreda, prichinennogo zdorov'yu cheloveka¼ pri zakrytoi travme plechevogo sustava.

The represented analysis shows the mechanism of formation of traumatic shoulder dislocation and potential intra-articular anatomic-morphological damages of humeral head according to the Hill-Sachs type in order to objectify the criteria of determination the severity of harm caused to human health. The potential Hill - Sachs classifications of shoulder dislocation are considered depending on size of humeral head defect. During the period of 2015 to 2020, 250 «conclusions¼ of forensic investigations of patients with the injuries of the shoulder joint were analyzed, performed by an expert traumatologist. It was identified, that in 8 patients with shoulder joint dislocation among 32 cases of shoulder injury, experts interpret this injury as a severe harm caused to human health without sufficient justification, using the conclusions of radiology specialists who gave a very brief description of X-rays indicating the diagnosis «fracture of humeral head according to the Hill-Sachs type¼. The severe harm caused to human health was detected correctly only in 2 patients with impression fracture of humeral head.

The V angle compliments radiographic assessment of acute acromioclavicular joint dislocations by differentiating between Rockwood types III versus V and by considering dynamic horizontal translation in coronal radiographs.

PURPOSE: Acromioclavicular joint (ACJ) dislocations are usually graded radiographically according to Rockwood, but differentiation between Rockwood types III and V may be ambiguous. The potentially clinically relevant horizontal instability is barely addressed in coronal radiographs. It was hypothesized that a new radiologic parameter (V angle) would complement ACJ diagnostics on anteroposterior radiographs by differentiating between cases of Rockwood III and V while also considering the aspect of dynamic horizontal translation (DHT). METHODS: Ninety-five patients with acute ACJ dislocations (Rockwood types III and V) were included retrospectively between 2017 and 2020. On anteroposterior views (weightbearing: n = 62, non-weight-bearing: n = 33), the coracoclavicular (CC) distance and the newly introduced V angle for assessing scapular orientation were measured bilaterally. This angle is referenced between the spinal column and a line crossing the superior scapular angle and the crossing point between the supraspinatus fossa and the medial base of the coracoid process, reported as the side-comparative difference (non-injured side *minus* injured side). DHT on Alexander views was divided into stable, partially unstable or completely unstable. RESULTS: The V angle on the injured side alone (mean 50.0°; 95% confidence interval (CI), 48.6°-51.3°) showed no correlation with the side-comparative CC distance [%] (r = - 0.040; n.s.). Thus, the V angle on the non-injured side was considered, displaying a normal distribution (n.s.) with a mean of 58.0° (95% CI, 56.6°-59.4°). The side-comparative V angle showed a correlation with the side-comparative CC distance (r = 0.83; p < 0.001) and was able to differentiate between Rockwood types III (4.7°; 95% CI, 3.9°-5.5°; n = 39) and V (10.3°; 95% CI, 9.7°-11.0°; n = 56) (p < 0.001). A cut-off value of 7° had a 94.6% sensitivity and an 82.1% specificity (area under curve, AUC: 0.954; 95% CI, 0.915-0.994). The side-comparative V angle was greater for cases with complete DHT (8.7°; 95% CI, 7.9°-9.5°; n = 78) than for cases with partial DHT (4.8°; 95% CI, 3.3°-6.3°; n = 16) (p < 0.001). A cut-off value of 5° showed a sensitivity of 84.6% and a specificity of 66.7% (AUC 0.824; 95% CI, 0.725-0.924). CONCLUSION: The scapular-based V angle on anteroposterior radiographs distinguishes between Rockwood types III and V as well as cases with partial or complete DHT. STUDY DESIGN: Diagnostic study. LEVEL OF EVIDENCE: Level II.

[A study of the correlation between glenohumeral joint congruence and stability in recurrent shoulder dislocations].

Objective: To investigate the correlation between glenohumeral joint congruence and stability in recurrent shoulder dislocations. Methods: Eighty-nine patients (89 sides) with recurrent shoulder dislocation admitted between June 2022 and June 2023 and met the selection criteria were included as study subjects. There were 36 males and 53 females with an average age of 44 years (range, 20-79 years). There were 40 cases of left shoulder and 49 cases of right shoulder. The shoulder joints dislocated 2-6 times, with an average of 3 times. The three-dimensional models of the humeral head and scapular glenoid were reconstructed using Mimics 20.0 software based on CT scanning images. The glenoid track (GT), inclusion index, chimerism index, fit index, and Hill-Sachs interval (HSI) were measured, and the degree of on/off track was judged (K value, the difference between HSI and GT). Multiple linear regression was used to analyze the correlation between the degree of on/off track (K value) and inclusion index, chimerism index, and fit index. Results: Multiple linear regression analysis showed that the K value had no correlation with the inclusion index ( P>0.05), and was positively correlated with the chimerism index and the fit index ( P<0.05). Regression equation was K=-24.898+35.982×inclusion index+8.280×fit index, R 2=0.084. Conclusion: Humeral head and scapular glenoid bony area and curvature are associated with shoulder joint stability in recurrent shoulder dislocations. Increased humeral head bony area, decreased scapular glenoid bony area, increased humeral head curvature, and decreased scapular glenoid curvature are risk factors for glenohumeral joint stability.

Performance of the Fresno-Quebec Rule in identifying patients with concomitant fractures not requiring a radiograph before shoulder dislocation reduction: a multicenter retrospective cohort study.

BACKGROUND AND IMPORTANCE: Although shoulder dislocation diagnosis is often solely based on clinical examination, physicians may order a radiograph to rule out a concomitant shoulder fracture before performing reduction. The Fresno-Québec decision rule aims to identify patients requiring a radiograph before reduction to avoid unnecessary systematic imaging. However, this novel approach needs further validation. OBJECTIVE: To evaluate the performance of the Fresno-Québec rule in identifying patients who do not require a prereduction radiograph and assess the variables associated with a clinically significant fracture. DESIGN, SETTINGS, AND PARTICIPANTS: A multicenter, retrospective cohort study from 2015 to 2021. Data were extracted from three ED university-affiliated tertiary-care centers. Patients aged ≥18 years with a final diagnosis of anterior glenohumeral dislocation were included. OUTCOMES MEASURE AND ANALYSIS: Accuracy metrics [sensitivity (Se), specificity (Sp), positive (PPV), negative predictive value (NPV), positive likelihood ratio (PLR) and negative likelihood ratio (NLR)] of the Fresno-Québec rule were measured. Multivariable logistic regression model was used to identify variables associated with the presence of a concomitant clinically significant fracture. MAIN RESULTS: A total of 2129 patients were included, among whom 9.7% had a concomitant fracture. The performance metrics of the Fresno-Québec rule were as follows: Se 0.96 95% confidence interval (0.92-0.98), Sp 0.36 (0.34-0.38), PPV 0.14 (0.12-0.16), NPV 0.99 (0.98-0.99), PLR 1.49 (1.42-1.55) and NLR 0.12 (0.06-0.23). A total of 678 radiographs could have been avoided, corresponding to a reduction of 35.2%. Age ≥40 years, first dislocation episode [odds ratio (OR) = 3.18 (1.95-5.38); P  < 0.001], the following mechanisms: road collision [OR = 6.26 (2.65-16.1)], low-level fall [OR = 3.49 (1.66-8.28)], high-level fall [OR = 3.95 (1.62-10.4)], and seizure/electric shock [OR = 10.6 (4.09-29.2)] were associated with the presence of a concomitant fracture. CONCLUSION: In this study, the Fresno-Québec rule has excellent Se in identifying concomitant clinically significant fractures in patients with an anterior glenohumeral dislocation. The use of this clinical decision rule may be associated with a reduction of approximately a third of unnecessary prereduction radiographs.

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.

Does glenoid bone loss accompany posterior shoulder instability with only labral tear? A magnetic resonance imaging-based study.

BACKGROUND: The primary aim of this study was to investigate bone loss in the glenoid with magnetic resonance imaging in posterior shoulder instability with only a labral tear. METHODS: A total of 76 patients operated on because of posterior and anteroposterior shoulder instability only with a labral tear between 2006 and 2019 (n = 40 and n = 36, respectively) were included in this study. The instability type, a presence of an additional superior labrum anteroposterior (SLAP) lesion, the number of dislocations, and the magnetic resonance imaging-based measurements (the glenoid diameter and the bone defect size in the glenoid, the Hill-Sachs lesion [HSL] and the reverse HSL [rHSL] length, the angle and the arc length of HSL and rHSL, and the humerus head diameter and its area) were analyzed. RESULTS: The size of the anterior glenoid defect, the rHSL measurements (length, angle, and arc length), and the ratio of the anterior glenoid defect size to the glenoid diameter were significantly higher for anteroposterior instability (P < .01) cases. There was no significant difference (P = .49, .64, and .82, respectively) for the presence of an additional SLAP pathology, the glenoid diameter, the posterior glenoid defect, and the ratio of the posterior glenoid defect size to the glenoid diameter in posterior and anteroposterior instability groups. The increased number of dislocations was associated with increased rHSL length and total arc length (P = .04 and .03, respectively). An additional SLAP lesion in posterior shoulder instabilities was not associated with the bone defect size (P = .29). CONCLUSION: Although the posterior shoulder instability with only a labral tear is likely to cause a bone defect, we have shown that the instability is not expected to be caused by the bone defect. Therefore, this study points out that only soft tissue repair without considering the bone defect could be promising in this patient group.