The acetabularization index: a novel measure of acromial bone loss prior to reverse shoulder arthroplasty.

BACKGROUND: Acromial stress fractures following reverse shoulder arthroplasty (RSA) have gained attention among specialized surgeons over the past decades craving answers regarding predisposing factors and technical aspects as how to avoid the complication. This study introduces the acetabularization index (AI) for the preoperative estimation of acromial bone loss attributed to acetabularization in cases of cuff tear arthropathy (CTA). METHODS: The acromiohumeral interval (AHI), extent of acromial acetabularization (AA), acromial height (AH), and width of acetabularization (r) were measured on preoperative radiographs and two-dimensional computed tomography scans (2D CT) of patients who underwent RSA within the timeline 2019-2023 for CTA. The AI calculated AI % = AA mm ÷ AH mm . The CTA grade was determined according to the Hamada classification. The AI values on radiographs and 2D CT were compared by a Student's t-test. Possible correlation between the AI and AHI was investigated via Pearson's coefficient. The intraclass correlation coefficient (ICC) was employed to test the interobserver reliability among two independent testers. RESULTS: The radiographs and 2D CT scans of thirty-three patients who underwent RSA were analyzed. The mean AHI, AH, AA, r, and AI values on radiographs were 5.5 ± 2 mm, 10 ± 2 mm, 2 ± 2 mm, 30 ± 4 mm, 16 ± 16%, respectively. On 2D CT, the corresponding mean values were 4.7 ± 2.5 mm, 10.8 ± 2.65 mm, 2.45 ± 2.35 mm, and 30 ± 4.5, and 22.3 ± 22%, respectively. There was a statistically significant difference between the AI values on radiographs and 2D CT (P = .000). The Pearson's correlation coefficient demonstrated a negative correlation between AI and AHI (r = - 0.33). Excellent reliability was observed by the ICC values for all parameters in both groups among two testers. CONCLUSION: The AI is a reliably measurable tool on radiographs and 2D CT scans; however, the measurements derived from radiographs vary significantly from CT based measurements due to projection restrictions. Grade IVB of the Hamada/Fukuda classification is associated with the highest AI values. Further research is warranted to assess the clinical utility of this index as a predictive tool for postoperative acromial stress fractures.

The Trillat procedure: the man and the technique revisited through the lens of arthroscopy.

The Trillat procedure, initially described by Albert Trillat, is historically one of the first techniques for addressing recurrent anterior shoulder instability, incorporating fascinating biomechanical mechanisms. After lowering, medializing, and fixing the coracoid process to the glenoid neck, the subcoracoid space is reduced, the subscapularis lowered, and its line of pull changed, accentuating the function of the subscapularis as a humeral head depressor centering the glenohumeral joint. Furthermore, the conjoint tendon creates a 'seatbelt' effect, preventing anteroinferior humeral head dislocation. Even though contemporary preferences lean towards arthroscopic Bankart repair with optional remplissage, bone augmentation, and the Latarjet procedure, enduring surgical indications remain valid for the Trillat procedure, which offers joint preservation and superior outcomes in two distinct scenarios: (i) older patients with massive irreparable cuff tears and anterior recurrent instability with an intact subscapularis tendon regardless of the extent of glenoid bone loss; (ii) younger patients with instability associated shoulder joint capsule hyperlaxity without concomitant injuries (glenoid bone loss, large Hill-Sachs lesion). Complications associated with the Trillat procedure include recurrent anterior instability, potential overtightening of the coracoid, leading to pain and a significant reduction in range of motion, risk of subcoracoid impingement, and restriction of external rotation by up to 10°, a limitation that is generally well-tolerated. The Trillat procedure may be an effective alternative technique for specific indications and should remain part of the surgical armamentarium for addressing anterior shoulder instability.

The base plate orientation angle: a plain radiographic technique for designing the base plate's inclination in reverse shoulder arthroplasty.

Background: Superior inclination of the base plate in reverse shoulder arthroplasty (RSA) is underestimated and may lead to major setbacks in terms of functional outcomes due to the altered biomechanics. Joint instability, scapular notching, and loosening of the glenoid component are considered the most serious sequelae. Therefore, a thorough preoperative radiological assessment of the affected shoulder joint and customized design of the prosthesis according to the glenoid morphology are decisive and directly correlated to the outcome. In this article, we propose a simple radiographic technique to assess the inclination of the glenoid preoperatively, which identifies the need for intraoperative correction. Materials and Methods: One hundred inconspicuous shoulder radiographs were included in the control group (CG) to define the normal ranges of the base plate orientation angle (BOA) and the base plate correction angle (BCA). Further, both angles were measured on 2-dimensional (2D) computed tomography scans of patients with proximal humerus fractures as well as radiographs, 2D and 3-dimensional (3D) computed tomography scans of patients with cuff tear arthropathy who underwent RSA between 2018 and 2021. The interobserver reliability among three independent testers was evaluated by calculating the intraclass correlation coefficient. In cuff tear arthropathy cases, the BOA and BCA measurements on different imaging modalities were compared using the Wilcoxon test. Possible variations of both angles' values based on glenoid erosion types, according to the Favard classification, were also investigated. Results: Regardless of the imaging modality used, the interobserver reliability was excellent among three independent observers. In the CG, the mean BOA and BCA values were 118° ± 6° and 17° ± 5°, respectively. The mean corrected BOA values of the CG and fracture group were 136° ± 5° and 140° ± 5°, respectively. In contrast to the BCA values, the BOA measurements on radiographs showed a statistically significant difference compared to those obtained on 2D- and 3D scans in the cuff arthropathy group. Further, both angles' values varied according to the extent and location of the glenoid erosion. The lowest mean BOA and highest mean BCA values were observed in cases with Favard glenoid type E3. Conclusions: The BOA and the BCA are reliable tools proposed to aid in precisely positioning the glenoid component in RSA in the preoperative setting. Whereas, the BOA determines the inclination of the inferior glenoid segment, the BCA represents the extent of correction required to obtain a neutral inclination of the base plate. Glenoid type E3 of the Favard classification with superior wear is particularly susceptible to base plate superior tilt.

The subtalar calcaneal angle: A novel angle for evaluation of displaced calcaneal fractures - A retrospective study.

Objectives: The radiological measurement of the Böhler angle (BA) and the critical angle of Gissane (CAG) is used not only to diagnose and corroborate the suspicion of the presence of calcaneal fractures but also to assess the prognosis of different injury patterns and to evaluate the operative reduction of calcaneal fractures. Notwithstanding, many previous studies indicated the poor intra- and interobserver reproducibility of both angles. In this retrospective study, we present the subtalar calcaneal angle (SCA) as an additional diagnostic tool -to BA and CAG-which can be applied on pre- and postoperative radiographs to assess calcaneal fractures involving the posterior facet. Design: Retrospective Study. Methods: Two retrospective groups were established, a 'CF-group' including radiographs of patients diagnosed with a calcaneal fracture and underwent operative treatment in the authors' traumatology department, and a 'control group' with 50 lateral calcaneal radiographs clear of skeletal lesions. Initially, the SCA, BA, and CAG were measured in both groups by three examiners. Those measurements were repeated one month later. The intra- and intertester reliabilities of all three angles were tested by determining the intraclass correlation coefficient (ICC). A paired t-test was used to prove the statistically significant difference between the SCA values for the pre- and postoperative groups, while the significant difference between the SCA values for the control and preoperative groups was tested through an independent-samples t-test. Results: The intra- and interobserver reliability of the SCA and the BA was in close proximity. The values of the SCA in both the control and postoperative groups were significantly different compared to the measurements of the preoperative group. The CAG showed poor intertester reliability. Conclusion: The subtalar calcaneal angle is a new instrument with proven reliability in estimating the prognosis of displaced calcaneal fractures and the postoperative alignment of the posterior facet. Level of clinical evidence: Diagnostic, Level III.