Arthroscopic Repair of Posterosuperior Rotator Cuff Tears Using a Modified Mason-Allen Suture Technique With a Transosseous-Equivalent Construct: A Technical Note.

Iterative evolutions in arthroscopic rotator cuff repair aim to improve its biomechanical and biological properties. This technical note describes an arthroscopic rotator cuff repair technique that combines the advantages of a modified Mason-Allen suture technique with the advantages of an arthroscopic transosseous-equivalent construct. Two alternatives for creating this construct are described. The Mason-Allen stitch is easy to perform, is cost-effective, and increases tissue security without tendon strangulation. The arthroscopic transosseous-equivalent construct increases footprint contact pressure and coverage, aiding healing of the repaired rotator cuff.

Navigated augmented reality through a head-mounted display leads to low deviation between planned, intra- and postoperative parameters during glenoid component placement of reverse shoulder arthroplasty: a proof-of-concept case series.

BACKGROUND: Navigated augmented reality (AR) through a head-mounted display (HMD) has led to accurate glenoid component placement in reverse shoulder arthroplasty (RSA) in an in-vitro setting. The purpose of this study is to evaluate the deviation between planned, intraoperative, and postoperative inclination, retroversion, entry point, and depth of the glenoid component placement during RSA, assisted by navigated AR through an HMD, in a surgical setting. METHODS: A prospective, multicenter study was conducted. All consecutive patients undergoing RSA in 2 institutions, between August 2021 and January 2023, were considered potentially eligible for inclusion in the study. Inclusion criteria were as follows: age >18 years, surgery assisted by AR through an HMD, and postoperative computed tomography (CT) scans at 6 weeks. All participants agreed to participate in the study and informed consent was provided in all cases. Preoperative CT scans were undertaken for all cases and used for 3-dimensional (3D) planning. Intraoperatively, glenoid preparation and component placement were assisted by a navigated AR system through an HMD in all patients. Intraoperative parameters were recorded by the system. A postoperative CT scan was undertaken at 6 weeks, and 3D reconstruction was performed to obtain postoperative parameters. The deviation between planned, intraoperative, and postoperative inclination, retroversion, entry point, and depth of the glenoid component placement was calculated. Outliers were defined as >5° for inclination and retroversion and >5 mm for entry point. RESULTS: Seventeen patients (9 females, 12 right shoulders) with a mean age of 72.8 ± 9.1 years (range, 47.0-82.0) met inclusion criteria. The mean deviation between intra- and postoperative measurements was 1.5° ± 1.0° (range, 0.0°-3.0°) for inclination, 2.8° ± 1.5° (range, 1.0°-4.5°) for retroversion, 1.8 ± 1.0 mm (range, 0.7-3.0 mm) for entry point, and 1.9 ± 1.9 mm (range, 0.0-4.5 mm) for depth. The mean deviation between planned and postoperative values was 2.5° ± 3.2° (range, 0.0°-11.0°) for inclination, 3.4° ± 4.6° (range, 0.0°-18.0°) for retroversion, 2.0 ± 2.5 mm (range, 0.0°-9.7°) for entry point, and 1.3 ± 1.6 mm (range, 1.3-4.5 mm) for depth. There were no outliers between intra- and postoperative values and there were 3 outliers between planned and postoperative values. The mean time (minutes : seconds) for the tracker unit placement and the scapula registration was 03:02 (range, 01:48 to 04:26) and 08:16 (range, 02:09 to 17:58), respectively. CONCLUSION: The use of a navigated AR system through an HMD in RSA led to low deviations between planned, intraoperative, and postoperative parameters for glenoid component placement.

Effect of patient-specific scapular morphology on the glenohumeral joint force and shoulder muscle force equilibrium: a study of rotator cuff tear and osteoarthritis patients.

Introduction: Osteoarthritis (OA) and rotator cuff tear (RCT) pathologies have distinct scapular morphologies that impact disease progression. Previous studies examined the correlation between scapular morphology and glenohumeral joint biomechanics through critical shoulder angle (CSA) variations. In abduction, higher CSAs, common in RCT patients, increase vertical shear force and rotator cuff activation, while lower CSAs, common in OA patients, are associated with higher compressive force. However, the impact of the complete patient-specific scapular morphology remains unexplored due to challenges in establishing personalized models. Methods: CT data of 48 OA patients and 55 RCT patients were collected. An automated pipeline customized the AnyBody™ model with patient-specific scapular morphology and glenohumeral joint geometry. Biomechanical simulations calculated glenohumeral joint forces and instability ratios (shear-to-compressive forces). Moment arms and torques of rotator cuff and deltoid muscles were analyzed for each patient-specific geometry. Results and discussion: This study confirms the increased instability ratio on the glenohumeral joint in RCT patients during abduction (mean maximum is 32.80% higher than that in OA), while OA patients exhibit a higher vertical instability ratio in flexion (mean maximum is 24.53% higher than that in RCT) due to the increased inferior vertical shear force. This study further shows lower total joint force in OA patients than that in RCT patients (mean maximum total force for the RCT group is 11.86% greater than that for the OA group), attributed to mechanically advantageous muscle moment arms. The findings highlight the significant impact of the glenohumeral joint center positioning on muscle moment arms and the total force generated. We propose that the RCT pathomechanism is related to force magnitude, while the OA pathomechanism is associated with the shear-to-compressive loading ratio. Overall, this research contributes to the understanding of the impact of the complete 3D scapular morphology of the individual on shoulder biomechanics.

Paget-Schroetter Syndrome in a Patient With Posterior Shoulder Subluxation: A Case Report.

ABSTRACT: Paget-Schroetter syndrome describes a primary thrombosis of the subclavian vein induced by effort. In most cases, the clinical presentation includes painful swelling, discoloration, and visible collateral circulation in the arm. Paget-Schroetter syndrome is treated with anticoagulation, rest, and physical therapy. In certain cases, invasive treatment such as thrombolysis and decompression surgery (first rib resection) may be necessary. We present the case of a 28-year-old healthy male patient with effort-induced deep vein thrombosis of the upper extremity after posterior shoulder subluxation. Anticoagulation, rest, and physical therapy were used to treat the patient, who became asymptomatic and was able to resume normal activities without restriction. To our knowledge, this is the first case of effort-induced upper extremity deep vein thrombosis after posterior shoulder subluxation. Paget-Schroetter syndrome is rare diagnosis that requires vigilance during musculoskeletal assessment for shoulder pain and swelling. The early detection, radiological confirmation, and prompt initiation of treatment are essential to successful management of Paget-Schroetter syndrome. The impact of associated posterior shoulder subluxation remains unclear.

Lower trapezius and latissimus dorsi transfer relieve teres minor activity into the physiological range in Collin D irreparable posterosuperior massive rotator cuff tears: a biomechanical analysis.

BACKGROUND: Tendon transfers are established techniques to regain external rotation mobility in patients with an irreparable, posterosuperior massive rotator cuff tear (MRCT). Posterosuperior MRCT with intact teres minor (type D MRCT) can lead to excessive teres minor loading to maintain external rotation. We hypothesize that tendon transfers are effective in relieving teres minor loading in type D MRCTs. Our aim was to biomechanically assess muscle synergism with latissimus dorsi (LD transfer) and lower trapezius (LT transfer) tendon transfer during external rotation at different abduction heights. METHODS: Using musculoskeletal modeling, we analyzed and compared the moment arm, muscle torque, and muscle activity between a healthy and type D MRCT pathologic model with and without the LD- or LT transfer at infraspinatus and teres minor insertion sites. Output measures were analyzed during external rotation at different abduction angles and 10-50 N resistance against external rotation. We assessed its impact on teres minor loading in a type D MRCT. Morphologic variations were parameterized using the critical shoulder angle and the acromiohumeral distance to address variations among patients. RESULTS: Both transfer types reduced teres minor torque and activity significantly, reaching physiological state at 40 N external resistance (P < .001), with insertion to infraspinatus site being more effective than teres minor site (P < .001). External rotation moment arms of LD transfer were larger than LT transfer at 90° abduction (25.1 ± 0.8 mm vs. 21.2 ± 0.6 mm, P < .001) and vice versa at 0° abduction (17.4 ± 0.5 mm vs. 24.0 ± 0.2 mm, P < .001). Although the healthy infraspinatus was the main external rotator in all abduction angles (50%-70% torque), a type D MRCT resulted in a 70%-90% increase of teres minor torque and an up to 7-fold increase in its activity leading to excessive loadings beyond 10 N resistance against external rotation. Varying the critical shoulder angle and the acromiohumeral distance led to minor variations in muscle moment arm and muscle activity. CONCLUSION: We identified biomechanical efficacy of both tendon transfers in type D MRCT regarding teres minor load relief and superior performance of the transfers at the infraspinatus insertion site.

How to treat stiffness after proximal humeral fractures?

Shoulder stiffness is a frequent complication after proximal humeral fractures treated with or without surgery. Shoulder stiffness is associated with high rates of absence from work and a significant financial burden for the healthcare system. Secondary stiffness is characterized by additional extracapsular adhesions, including subacromial, subcoracoid, and subdeltoid spaces, usually derived from post-fracture or post-surgical extraarticular hematomas. Several secondary causes may coexist with capsular and extracapsular adhesions decreasing the shoulder motion, such as malunion, nonunion, metalwork failure, infection, and osteoarthritis, among others. Conservative treatment, usually prescribed for primary shoulder stiffness, has shown unfavorable results in secondary stiffness, and surgical intervention may be required. Surgical interventions need to be patient-specific. Usually, open or arthroscopic fibro-arthrolysis and subacromial release are performed, together with plate removal and biceps tenotomy/tenodesis. In severe osteoarthritis, shoulder replacement may be indicated. Ruling out infection is recommended in every case.

Current concepts in chronic traumatic anterior shoulder instability.

Chronic traumatic anterior shoulder instability can be defined as recurrent trauma-associated shoulder instability requiring the assessment of three anatomic lesions: a capsuloligamentous and/or labral lesion; anterior glenoid bone loss and a Hill-Sachs lesion. Surgical treatment is generally indicated. It remains controversial how risk factors should be evaluated to decide between a soft-tissue, free bone-block or Latarjet-type procedure. Patient risk factors for recurrence are age; hyperlaxity; competitive, contact and overhead sports. Trauma-related factors are soft tissue lesions and most importantly bone loss with implications for treatment. Different treatment options are discussed and compared for complications, return to sports parameters, short- and long-term outcomes and osteoarthritis. Arthroscopic Bankart and open Latarjet procedures have a serious learning curve. Osteoarthritis is associated with the number of previous dislocations as well as surgical techniques. Latarjet-type procedures have the lowest rate of dislocation recurrence and if performed correctly, do not seem to increase the risk of osteoarthritis.

Glenoid component placement in reverse shoulder arthroplasty assisted with augmented reality through a head-mounted display leads to low deviation between planned and postoperative parameters.

BACKGROUND: Navigated augmented reality (AR) through a head-mounted display (HMD) may lead to accurate glenoid component placement in reverse shoulder arthroplasty (RSA). The purpose of this study is to evaluate the deviation between planned, intra- and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement assisted by a navigated AR through HMD during RSA. METHODS: Both shoulders of 6 fresh frozen human cadavers, free from fractures or other bony pathologies, were used. Preoperative computed tomography (CT) scans were used for the 3-dimensional (3D) planning. The glenoid component placement was assisted using a navigated AR system through an HMD in all specimens. Intraoperative inclination, retroversion, depth, and rotation were measured by the system. A postoperative CT scan was performed. The pre- and postoperative 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement. Additionally, a comparison between intra- and postoperative values was calculated. Outliers were defined as >10° inclination, >10° retroversion, >3 mm entry point. RESULTS: The registration algorithm of the scapulae prior to the procedure was correctly completed for all cases. The deviations between planned and postoperative values were 1.0° ± 0.7° for inclination, 1.8° ± 1.3° for retroversion, 1.1 ± 0.4 mm for entry point, 0.7 ± 0.6 mm for depth, and 1.7° ± 1.6° for rotation. The deviation between intra- and postoperative values were 0.9° ± 0.8° for inclination, 1.2° ± 1.1° for retroversion, 0.6 ± 0.5 mm for depth, and 0.3° ± 0.2° for rotation. There were no outliers between planned and postoperative parameters. CONCLUSION: In this study, the use of a navigated AR system through an HMD for RSA led to low deviation between planned and postoperative values and between intra- and postoperative parameters.

Massive rotator cuff tears with short tendon length can be successfully repaired using synthetic patch augmentation.

BACKGROUND: Choosing the optimal treatment for massive rotator cuff tears (MRCTs) still poses a surgical problem. In MRCTs with good muscle quality, but short tendon length, nonaugmented repairs lead to high failure rates of up to 90%. The aim of the study was to evaluate midterm clinical and radiologic outcomes of massive rotator cuff tears with good muscle quality, but short tendon length, which were repaired with synthetic patch augmentation. METHODS: A retrospective study of patients who underwent arthroscopic or open rotator cuff repairs with patch augmentation between 2016 and 2019 was performed. We included patients older than 18 years, who presented with an MRCT confirmed by an magnetic resonance imaging (MRI) arthrogram showing good muscle quality (Goutallier ≤ II) and short tendon length (length <15 mm). Constant-Murley score (CS), Subjective Shoulder Value (SSV), and range of motion (ROM) were compared pre- and postoperatively. We excluded patients older than 75 years or with presence of rotator cuff arthropathy Hamada stage ≥2a. Patients were followed up for 2 years minimum. Clinical failures were defined by reoperation, forward flexion <120° or a relative CS < 70. Structural integrity of the repair was assessed using an MRI scan. Comparison between different variables and outcomes was performed using Wilcoxon-Mann-Whitney and χ2 tests. RESULTS: Fifteen patients (mean age 57 years, 13 [86.7%] male, 9 [60%] right shoulders) were reevaluated with a mean follow-up of 43.8 months (27-55 months). There was a significant improvement in the absolute CS (from 33 to 81 points, P = .03), the relative CS (from 41% to 88%, P = .04), the SSV (from 31% to 93%, P = .007), and forward flexion (from 111° to 163°, P = .004) but not in external rotation (from 37° to 38°, P = .5). There were 3 clinical failures (1 atraumatic, 2 traumatic) with reoperations (2 reverse total shoulder arthroplasties and 1 refixation). Structurally, there were 3 Sugaya grade 4 and 5 Sugaya grade 5 reruptures resulting in a retear rate of 53%. The presence of a complete or partial rerupture was not associated with inferior outcomes compared with intact cuff repairs. There were no correlations between the grade of retraction, muscle quality, or rotator cuff tear configuration and rerupture or functional outcomes. CONCLUSION: Patch augmented cuff repair leads to a significant improvement of functional and structural outcomes. Partial reruptures were not associated with inferior functional outcomes. Prospective randomized trials are needed to confirm the results found in our study.

Deep-Learning-Based Segmentation of the Shoulder from MRI with Inference Accuracy Prediction.

Three-dimensional (3D)-image-based anatomical analysis of rotator cuff tear patients has been proposed as a way to improve repair prognosis analysis to reduce the incidence of postoperative retear. However, for application in clinics, an efficient and robust method for the segmentation of anatomy from MRI is required. We present the use of a deep learning network for automatic segmentation of the humerus, scapula, and rotator cuff muscles with integrated automatic result verification. Trained on N = 111 and tested on N = 60 diagnostic T1-weighted MRI of 76 rotator cuff tear patients acquired from 19 centers, a nnU-Net segmented the anatomy with an average Dice coefficient of 0.91 ± 0.06. For the automatic identification of inaccurate segmentations during the inference procedure, the nnU-Net framework was adapted to allow for the estimation of label-specific network uncertainty directly from its subnetworks. The average Dice coefficient of segmentation results from the subnetworks identified labels requiring segmentation correction with an average sensitivity of 1.0 and a specificity of 0.94. The presented automatic methods facilitate the use of 3D diagnosis in clinical routine by eliminating the need for time-consuming manual segmentation and slice-by-slice segmentation verification.

Effect of PARP-1 Inhibition on Rotator Cuff Healing: A Feasibility Study Using Veliparib in a Rat Model of Acute Rotator Cuff Repair.

BACKGROUND: PARP-1 (poly[ADP-ribose]) was shown to influence the inflammatory response after rotator cuff tear, leading to fibrosis, muscular atrophy, and fatty infiltration in mouse rotator cuff degeneration. So far, it is not known how PARP-1 influences enthesis healing after rotator cuff tear repair. HYPOTHESIS/PURPOSE: This study aimed to examine the feasibility of oral PARP-1 inhibition and investigate its influence on rat supraspinatus enthesis and muscle healing after rotator cuff repair. The hypothesis was that oral PARP-1 inhibition would improve enthesis healing after acute rotator cuff repair in a rat model. STUDY DESIGN: Controlled laboratory study. METHODS: In 24 Sprague-Dawley rats, the supraspinatus tendon was sharply detached and immediately repaired with a single transosseous suture. The rats were randomly allocated into 2 groups, with the rats in the inhibitor group receiving veliparib with a target dose of 12.5 mg/kg/d via drinking water during the postoperative recovery period. The animals were sacrificed 8 weeks after surgery. For the analysis, macroscopic, biomechanical, and histologic methods were used. RESULTS: Oral veliparib was safe for the rats, with no adverse effects observed. In total, the inhibitor group had a significantly better histologic grading of the enthesis with less scar tissue formation. The macroscopic cross-sectional area of the supraspinatus muscles was 10.5% higher (P = .034) in the inhibitor group, which was in agreement with an 8.7% higher microscopic muscle fiber diameter on histologic sections (P < .0001). There were no statistically significant differences in the biomechanical properties between the groups. CONCLUSION: This study is the first to investigate the influence of PARP-1 inhibition on healing enthesis. On the basis of these findings, we conclude that oral veliparib, which was previously shown to inhibit PARP-1 effectively, is safe to apply and has beneficial effects on morphologic enthesis healing and muscle fiber size. CLINICAL RELEVANCE: Modulating the inflammatory response through PARP-1 inhibition during the postoperative healing period is a promising approach to improve enthesis healing and reduce rotator cuff retearing. With substances already approved by the Food and Drug Administration, PARP-1 inhibition bears high potential for future translation into clinical application.

Glenoid Component Placement Assisted by Augmented Reality Through a Head-Mounted Display During Reverse Shoulder Arthroplasty.

Component positioning is a key factor for avoiding complications and improving functional outcomes in reverse shoulder arthroplasty. Preoperative planning can improve component positioning. However, translating the preoperative plan into the surgical procedure can be challenging. This is particularly the case for the glenoid component positioning in severe deformity or limited visualization of the scapula. Different computational-assisted techniques have been developed to aid implementation of the preoperative plan into the surgical procedure. Navigated augmented reality (AR) refers to the real world augmented with virtual real-time information about the position and orientation of instruments and components. This information can be presented through a head-mounted display (HMD), which enables the user to visualize the virtual information directly overlaid onto the real world. Navigated AR systems through HMD have been validated for shoulder arthroplasty using phantoms and cadavers. This article details a step-by-step guide use of a navigated AR system through HMD, in the placement of the glenoid bony-augmented component.

Patient-specific instrumentation reduces deviations between planned and postosteotomy humeral retrotorsion and height in shoulder arthroplasty.

BACKGROUND: Patient-specific instrumentation (PSI) may potentially improve humeral osteotomy in shoulder arthroplasty. The purpose of this study was to compare the deviation between planned and postosteotomy humeral inclination, retrotorsion, and height in shoulder arthroplasty, using PSI vs. standard cutting guides (SCG). METHODS: Twenty fresh-frozen cadaveric specimens were allocated to undergo humeral osteotomy using either PSI or SCG, such that the 2 groups have similar age, gender, and side. Preosteotomy computed tomography (CT) scan was performed and used for the 3-dimensional (3D) planning. The osteotomy procedure was performed using a PSI designed for each specimen or an SCG depending on the group. A postosteotomy CT scan was performed. The preosteotomy and postosteotomy 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postosteotomy inclination, retrotorsion, and height. Outliers were defined as cases with 1 or more of the following deviations: >5° inclination, >10° retrotorsion, and >3 mm height. The deviation and outliers in inclination, retrotorsion, and height were compared between the 2 groups. RESULTS: The deviations between planned and postosteotomy parameters were similar among the PSI and SCG groups for inclination (P = .260), whereas they were significantly greater in the SCG group for retrotorsion (P < .001) and height (P = .003). There were 8 outliers in the SCG group, compared with only 1 outlier in the PSI group (P = .005). Most outliers in the SCG group were due to deviation >10° in retrotorsion. CONCLUSION: After 3D planning, PSI had less deviation between planned and postosteotomy humeral retrotorsion and height, relative to SCG.

What's the best surgical repair technique of an ulnar styloid fracture? A biomechanical comparison of different techniques.

INTRODUCTION: 8-10% of all Ulnar styloid fractures (USF) accompanying distal radius fractures are addressed surgically. The surgical fixation has to counteract forces of translation and rotation acting on the distal radioulnar joint (DRUJ). The different technics used were never compared biomechanically. Our study aims to compare the effects of different techniques of USF fixation on the forearm rotation and the dorsal-palmar (DP)-translation of the DRUJ. MATERIAL AND METHODS: 9 forearm specimens were mounted on a custom testing system. Load was applied for Pronosupination and DP-translation with the forearm placed in neutral position, pronation and supination. The positional change of the DRUJ was measured using a MicroScribe. Six different, sequential conditions were tested in the same specimen: intact, USF and 4 repair techniques (2 K-wire, tension band wiring (TBW), headless compression screw, suture anchor). RESULTS: The USF significantly increased DP-translation and pronosupination compared to the intact condition. The DP-translation in neutral was reduced significantly with all four techniques compared to the USF condition. TBW and suture anchor also showed a significant difference to the K-wire fixation. In supination only the TBW and suture anchor significantly decreased DP-Translation. The rotational stability of the DRUJ was only restored by the K-wire fixation and the TBW. CONCLUSIONS: All four USF repair techniques partially restored translational stability; however, only K-wire fixation and TBW techniques restored rotational stability. TBW was biomechanically superior to the other techniques as it restored translational stability and rotational stability.

Nonoperative and Operative Soft-Tissue, Cartilage, and Bony Regeneration and Orthopaedic Biologics of the Shoulder: An Orthoregeneration Network (ON) Foundation Review.

Orthoregeneration is defined as a solution for orthopaedic conditions that harnesses the benefits of biology to improve healing, reduce pain, improve function, and optimally, provide an environment for tissue regeneration. Options include drugs, surgical intervention, scaffolds, biologics as a product of cells, and physical and electro-magnetic stimuli. The goal of regenerative medicine is to enhance the healing of tissue after musculoskeletal injuries as both isolated treatment and adjunct to surgical management, using novel therapies to improve recovery and outcomes. Various orthopaedic biologics (orthobiologics) have been investigated for the treatment of pathology involving the shoulder including the rotator cuff tendons, glenohumeral articular cartilage, glenoid labrum, the joint capsule, and bone. Promising and established treatment modalities include hyaluronic acid (HA); platelet-rich plasma (PRP) and platelet rich concentrates (PRC); bone marrow aspirate (BMA) comprising mesenchymal stromal cells (MSCs alternatively termed medicinal signaling cells and frequently, misleadingly labelled "mesenchymal stem cells"); MSC harvested from adipose, umbilical, or placental sources; factors including vascular endothelial growth factors (VEGF), basic fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGFß), bone morphogenic protein (BMP), and matrix metalloproteinases (MMPs); prolotherapy; pulsed electromagnetic field therapy; microfracture and other marrow-stimulation techniques; biologic resurfacing using acellular dermal allografts, allograft Achilles tendons, allograft lateral menisci, fascia lata autografts, and porcine xenografts; osteochondral autograft or allograft); and autologous chondrocyte implantation (ACI). Studies involving hyaluronic acid, platelet rich plasma, and medicinal signaling cells of various origin tissues have shown mixed results to-date as isolated treatments and as surgical adjuncts. Despite varied results thus far, there is great potential for improved efficacy with refinement of current techniques and translation of burgeoning preclinical work. LEVEL OF EVIDENCE: Level V, expert opinion.

Evaluation of the Circles Measurement and the ABC Classification of Acromioclavicular Joint Injuries.

BACKGROUND: Acromioclavicular joint (ACJ) injuries are common. Despite this, it remains unclear how best to assess, classify, and manage these cases. A simple, reliable, valid, and accurate radiographic parameter to measure ACJ displacement would allow improved consistency of diagnosis and subsequent treatment pathways. PURPOSE: To evaluate "the circles measurement" and associated "ABC classification" as a tool for assessing ACJ displacement and injury classification. STUDY DESIGN: Descriptive laboratory study. METHODS: The circles measurement is taken from a lateral Alexander radiograph of the shoulder. The measurement is the center-to-center distance between 2 circles drawn to define the lateral extent of the clavicle and the anteromedial extent of the acromion; it is independent of the displacement plane, judging total ACJ displacement in any direction rather than trying to quantify vertical and/or horizontal displacement. When utilized clinically, the circles measurement is a single measurement calculated as the difference between values recorded for the injured and uninjured sides. Validation of the circles measurement was performed using lateral Alexander radiographs (including ±20° projection error in all planes) and computed tomography of standardized ACJ injury simulations. We assessed inter- and intrarater reliability, convergent validity, and discriminant validity of the circles measurement and subsequently generated a classification of ACJ injury based on displacement. RESULTS: Reliability and validity of the circles measurement was excellent throughout. Interrater reliability (ICC [intraclass correlation coefficient] [2,1], 95% CI; n = 78; 4 observers) was 0.976 (0.964-0.985). Intrarater reliability (ICC [2,1]; 95% CI; n = 78; 2 measures) was 0.998 (0.996-0.998). Convergent validity (Pearson correlation coefficient, r) was 0.970 for ideal radiographs and 0.889 with ±20° projection error in all planes. Discriminant validity, with 1-way analysis of variance, showed a P value of <.0001 and effect size (η2) of 0.960, with the ability to distinguish between the previously defined stable (Rockwood IIIA) and unstable (Rockwood IIIB) injuries. The results permitted objective, statistically sound parameters for the proposed ABC classification system. CONCLUSION: The circles measurement is a simple, reliable, valid, accurate, and resilient parameter for assessing ACJ displacement and can be used in conjunction with the proposed ABC classification to define ACJ injuries more accurately and objectively than previously described. CLINICAL RELEVANCE: This novel parameter has the potential to standardize the initial assessment and possibly the subsequent clinical management of ACJ injuries, in addition to providing a standardized measure for future research.

Editorial Commentary: No Difference in Knotted Versus Knotless Anchors for Labral Repair in the Shoulder.

In comparing knotted versus knotless anchors for labral repair in the shoulder, there are no significant differences in clinical outcomes or biomechanical properties including load to failure.

BiPOD arthroscopically assisted bidirectional stabilisation technique for high-grade acromioclavicular joint injury: two-year clinical and radiological outcomes.

PURPOSE: The purpose of this study was to evaluate the intermediate-term clinical and radiological outcomes for acute, unstable acromioclavicular joint (ACJ) injuries treated with the arthroscopically assisted BiPOD stabilisation technique. METHODS: Twenty-three patients who sustained acute, unstable ACJ injuries were included in this prospective study. We recorded demographics, injury classification, time to surgery, clinical scores, radiological outcomes and complications; each patient completed a minimum of 2 years post-operative observation. RESULTS: Mean follow-up was 26 months (range, 24-34). Clinical outcomes scores demonstrated good 2-year results: relative Constant score, 97.9/100; ACJ Index, 89.4/100; Subjective Shoulder Value, 92.4/100 and Taft = 11.1/12. Final C-C distance showed a mean of 0.7 mm (SD ± 1.8 mm) at 2 years. Complication rate was 9%. CONCLUSION: The BiPOD technique shows excellent, reliable intermediate-term results with a favourable complication rate compared to existing techniques; it provides a comprehensive surgical option for the stabilisation of acute ACJ injuries restoring both vertical and horizontal stability.

A biomechanical study comparing the mean load to failure of two different osteosynthesis techniques for step-cut olecranon osteotomy.

Background: Olecranon osteotomies are frequently used to expose distal humeral intraarticular fractures. The step-cut olecranon osteotomy (SCOOT) is an augmented version of the oblique olecranon osteotomy, which has recently been evaluated biomechanically with tension band wiring (TBW) fixation. However, complications with TBW are common. In this study, we, therefore, compared the mean load to failure of TBW with compression screws for SCOOT fixation. We hypothesized a higher load to failure for the compression screw group. Methods: We performed a SCOOT on 36 Sawbones. Eighteen were fixed with TBW, and another 18 with two compression screws. The humeroulnar joint was simulated using an established test setup, which allows the application of triceps traction force through a tendon model to the ulna, while the humeroulnar joint is in a fixed position. Eight models of each fixation group were tested at 20°, and eight at 70° of flexion by isometrical loading until failure, which was defined as either a complete fracture or gap formation of more than 2 mm at the osteotomy site. Results: At 20° of flexion, mean load to failure was similar between the TBW group (1360 ± 238 N) and the compression screw group (1401 ± 261 N) (P = .88). Also, at 70° of flexion, the mean load to failure was similar between the TBW group (1398 ± 215 N) and the compression screw group (1614 ± 427 N) (P = .28). Conclusions: SCOOTs fixed with TBW and compression screws showed similar loads to failure. A SCOOT fixed with compression screws might be a valuable alternative for surgeons when treating intraarticular distal humeral fractures. However, future in vivo studies are necessary to confirm our results in a clinical setting.

Impact of humeral and glenoid component variations on range of motion in reverse geometry total shoulder arthroplasty: a standardized computer model study.

BACKGROUND: Multiple modifications of reverse total shoulder arthroplasty (RTSA) since the first Grammont design have developed to improve range of motion (ROM) and avoid notching. The effect of these changes in shoulder kinematics and the best compromise for ROM is still under debate. This computer simulation study evaluates the influence of humeral design, humeral neck-shaft angle (NSA), glenoid lateralization, and glenoid eccentricity on ROM of RTSA. METHODS: We created a 3-dimensional computer model from computed tomography scans of 13 patients with primary osteoarthritis simulating implantation of a standardized reverse shoulder arthroplasty. We analyzed the effect of 4 different variables on impingement-free ROM: humeral design (inlay vs. semi-inlay vs. onlay), humeral NSA (135° vs. 145° vs. 155°), glenoid lateralization, and glenoid eccentricity on ROM. RESULTS: The use of different humeral stem designs did not have a significant effect on total global ROM. Reducing NSA demonstrated a significant increase in adduction, and external and internal rotation in adduction, whereas a decrease in abduction and external rotation in abduction. Glenosphere lateralization was the most effective method for increasing total global ROM (P < .0001); however, extreme lateralization (+12 mm) did not show significant benefit compared with moderate lateralization (+4 mm). Glenosphere eccentricity increased only adduction and internal rotation in adduction. CONCLUSION: Only glenoid lateralization has a significant effect on increasing total global ROM in RTSA. The use of the semi-inlay 145° model combined with 4 mm lateralization and 2 mm inferior eccentricity represents the middle ground and the most universal approach in RTSA.