Factors Influencing Acromial and Scapular Spine Strain after Reverse Total Shoulder Arthroplasty: A Systematic Review of Biomechanical Studies

Background: Acromial and scapular spine fractures after reverse total shoulder arthroplasty (RTSA) can be devastating complications leading to substantial functional impairments. The purpose of this study was to review factors associated with increased acromial and scapular spine strain after RTSA from a biomechanical standpoint. Methods: A systematic review of the literature was conducted based on PRISMA guidelines. PubMed, Embase, OVID Medline, and CENTRAL databases were searched and strict inclusion and exclusion criteria were applied. Each article was assessed using the modified Downs and Black checklist to appraise the quality of included studies. Study selection, extraction of data, and assessment of methodological quality were carried out independently by two of the authors. Only biomechanical studies were considered. Results: Six biomechanical studies evaluated factors associated with increased acromial and scapular spine strain and stress. Significant increases in acromial and scapular spine strain were found with increasing lateralization of the glenosphere in four of the included studies. In two studies, glenosphere inferiorization consistently reduced acromial strain. The results concerning humeral lateralization were variable between four studies. Humeral component neck-shaft angle had no significant effect on acromial strain as analysed in one study. One study showed that scapular spine strain was significantly increased with a more posteriorly oriented acromion (55° vs. 43°; p < 0.001). Another study showed that the transection of the coracoacromial ligament increased scapular spine strain in all abduction angles (p < 0.05). Conclusions: Glenoid lateralization was consistently associated with increased acromial and scapular spine strain, whereas inferiorization of the glenosphere reduced strain in the biomechanical studies analysed in this systematic review. Humeral-sided lateralization may increase or decrease acromial or scapular spine strain. Independent of different design parameters, the transection of the coracoacromial ligament resulted in significantly increased strains and scapular spine strains were also increased when the acromion was more posteriorly oriented. The results found in this systematic review of biomechanical in-silico and in-vitro studies may help in the surgical planning of RTSA to mitigate complications associated with acromion and scapular spine fracture.

Open Latarjet-Patte Procedure for Anterior Shoulder Stabilization: Critical Steps and Pearls for the Walch Technique

Background: Latarjet is a term used for different techniques and modifications to expose the glenoid and to transfer and fix the coracoid. The procedure is intricate and technically demanding. Outcomes and complications are heterogeneous in the literature. A master technique, the Walch technique, has been practiced for decades, with outstanding long-term results and patient satisfaction. Indications: Documented anterior dislocations with evidence for emergency reduction, with or without hyperlaxity and confirmation of a traumatic capsuloligamentous lesion. Contraindications include voluntary dislocations and multidirectional instability without these criteria. The Instability Severity Index Score can guide decision making on whether Bankart surgery is sufficient. Large Hill-Sachs lesions may be an indication for additional remplissage. Technique Description: Three key maneuvers and 6 surgical stages need to be mastered for consistent results. Key maneuvers include: (1) arm positioning for all stages, (2) retractor placement, and (3) safe conjoint tendon releases. Six key stages include: (1) coracoid exposure and initial release; (2) osteotomy and subsequent release; (3) bone preparation; (4) subscapularis split and arthrotomy; (5) 360° scapula neck exposure; and (6) cornerstone drill hole positioning, fixation, and simple capsuloplasty. Specific arm positioning facilitates coracoid exposure, releases, subscapularis split, arthrotomy, and retractor insertion, as well as capsular repair. A 360° anterior scapula neck exposure is crucial to drill the inferior cornerstone hole (2.5 for 4.0 partially threaded cancellous screw) 7 mm medial to the articular surface with mandatory direction parallel to the articular surface. The bone block can be dialed to the exact position, preventing lateral overhang. The capsule is closed to the coracoacromial ligament stump in 45° of external rotation. Results: A series of >80 cases with minimum 1-year follow-up (range: 1-5 years) demonstrated excellent results. Outcomes were good to excellent (small saphenous vein >80% in 95% of cases; Constant score >90% and Rowe score > 90%) in keeping with the Walch results (>1000 cases). The complication rate was low: 1 early coracoid fracture (1.3%), no dislocation and neurological complications, no new arthritis or progression, and good coracoid position without lateral overhang. Conclusion: The Walch technique, although technically demanding, provides excellent, consistently reproducible results once the 3 key surgical maneuvers and 6 stages of the procedure are mastered.

Morphology of the Undersurface of the Anterolateral Acromion and Its Relationship to Surrounding Structures

Background: A better understanding of the morphology underneath the acromion is needed to prevent complications after arthroscopic subacromial decompression. The precise correlations between the morphologic features underneath the acromion and the surrounding structures including the attachment of the coracoacromial ligament (CAL) and the origin of the deltoid middle head have not yet been determined in the absence of artifacts on the bony surface caused by dissection techniques. Moreover, anatomic findings in previous studies using only older-aged cadavers or dried bones may not reflect the morphologic features of younger and healthy specimens. Purpose: To characterize the anterolateral structures morphologically in the inferior aspect of the acromion, assess the relationships of these structures with surrounding structures without dissection artifacts on the bony surface, and verify the cadaveric data in the asymptomatic shoulders of living middle-aged patients. Study Design: Descriptive laboratory study. Methods: We initially analyzed the relationship between the morphology of the anterolateral structures and surrounding structures in 18 cadaveric shoulders (mean age, 81.8 years), 15 of which were subjected to macroscopic investigation of the CAL attachment and 3-dimensional micro—computed tomography investigation with radiopaque markers and 3 of which were subjected to histologic examination. We also analyzed the morphology underneath the anterolateral acromion in 24 asymptomatic shoulders of middle-aged patients (mean age, 54.8 years) to verify the cadaveric data. In both the cadaveric shoulders and the asymptomatic shoulders of live patients, the long axis, width, and height of the anterolateral prominence were measured by use of 3-dimensional CT imaging. Results: In cadavers, the anterolateral prominence underneath the acromion corresponded to the attachment of the CAL. Histologic evaluation revealed that the CAL was continuous to the deep layer of the deltoid middle head in the lateral acromion. The study in asymptomatic shoulders of middle-aged patients revealed bony prominences similar to those observed in cadavers. Conclusion: The anterolateral prominence, which corresponds to the attachment of the CAL below the acromion, may be a native structure below the acromion. Moreover, the CAL is continuous to the deep layer of the deltoid middle head in the lateral acromion.

Does Preservation of Coracoacromial Ligament Reduce the Acromial Stress Pathology Following Reverse Total Shoulder Arthroplasty?

Introduction Acromial pathologies (AP), such as acromial stress reaction (ASR), acromial stress occult fracture (ASOF), and acromial stress fracture (ASF), are known as complications that deteriorate the clinical score and patient satisfaction after reverse total shoulder arthroplasty (RSA). Several factors that increase stress on the acromion have been reported as risk factors for AP, but this is also unclear. Thecoracoacromial ligament (CAL) is a structure that distributes the stress loading on such an acromion, although its importance has been mentioned, there is a lack of research. Therefore, we investigated the incidence of AP according to the preservation of the CAL and whether it is a risk factor. Methods The study was retrospectively conducted on patients who underwent RSA from 2016 and 2018. Patients with CAL transection was classified into group 1 and CAL preservation was classified into group 2. ASR and ASOF were identified through symptoms and ultrasound, and ASF identified through simple radiograph or computed tomography. The incidence of AP in each group was checked and compared. Results Of the total of 265 patients. Among 197 cases of group 1, 21 cases of ASR(10.7%), 28 cases of ASOF (14.2%),10 cases of ASF (5.1%), and 59 cases of total AP (29.4%). Among 68 cases in group 2, 2 cases (2.9%) of ASR, 6 cases of ASOF(8.8%), 1 case of ASF (1.5%), and 9 cases of total AP (13.2%). It was confirmed that ASR and ASOP were significantly decreased in the group preserving CAL. (P = .008) Conclusion In the case of preservation of CAL during surgery, it was confirmed that the incidence of ASR, ASOF was reduced. Therefore, preservation of CAL can be regarded as a modifiable risk factor that can reduce the risk of AP by distributing the stress applied to acromion after RSA surgery.

Modified Arthroscopic Latarjet Procedure: Suture-button Fixation will not Cause Obvious Increasement of Superior Instability at 5-Year Follow-up

Background: Whether coracoacromial ligament (CAL) release during Latarjet procedure will increase superior instability of shoulder joint postoperatively remains controversial. This study aims to observe changes in the acromiaohumeral distance (AHD) of patients who underwent modified double-button Latarjet procedure and provide evidence to address the issue.Methods: A retrospective analysis was conducted among 155 patients who underwent modified double-button Latarjet procedure in our department from 2013 to 2015. Preoperative CT scan of bilateral shoulders were used for glenoid defect evaluation. CT scans were performed immediately after operation (PO 0) and during the follow-up at 6, 36, and 60 months postoperatively (POM) to observe the healing and remodeling of the graft, and AHD was measured. The intact sides were set as control group. VAS and objective shoulder scores, including ASES, ROWE, and Walch-Duplay scores, were recorded at each time point.Results: A total of 104 cases who met the criteria completed follow up. The average follow-up time was 62.6 ± 2.4 months. Compared with preoperative conditions, the function scores of the shoulders were significantly improved at the last follow-up. There were no statistical differences of the AHD values between bilateral shoulders preoperatively. The AHD values at PO 0 and POM 6 were significantly higher than those of intact side (p < 0.05). The AHD values at POM 36 and 60 were slightly higher than those of intact side and the differences were statistically significant (p < 0.05).Conclusions: The modified double-button Latarjet procedure not only offers satisfactory therapeutic effect but also will not cause obvious superior instability at the 5-year follow-up.