Arthroscopic Bristow-Latarjet Combined With Bankart Repair Restores Shoulder Stability in Patients With Glenoid Bone Loss

BACKGROUND: Arthroscopic Bankart repair alone cannot restore shoulder stability in patients with glenoid bone loss involving more than 20% of the glenoid surface. Coracoid transposition to prevent recurrent shoulder dislocation according to Bristow-Latarjet is an efficient but controversial procedure. QUESTIONS/PURPOSES: We determined whether an arthroscopic Bristow-Latarjet procedure with concomitant Bankart repair (1) restored shoulder stability in this selected subgroup of patients, (2) without decreasing mobility, and (3) allowed patients to return to sports at preinjury level. We also evaluated (4) bone block positioning, healing, and arthritis and (5) risk factors for nonunion and coracoid screw pullout. METHODS: Between July 2007 and August 2010, 79 patients with recurrent anterior instability and bone loss of more than 20% of the glenoid underwent arthroscopic Bristow-Latarjet-Bankart repair; nine patients (11%) were either lost before 2-year followup or had incomplete data, leaving 70 patients available at a mean of 35 months. Postoperative radiographs and CT scans were evaluated for bone block positioning, healing, and arthritis. Any postoperative dislocation or any subjective complaint of occasional to frequent subluxation was considered a failure. Physical examination included ROM in both shoulders to enable comparison and instability signs (apprehension and relocation tests). Rowe and Walch-Duplay scores were obtained at each review. Patients were asked whether they were able to return to sports at the same level and practice forced overhead sports. Potential risk factors for nonhealing were assessed. RESULTS: At latest followup, 69 of 70 (98%) patients had a stable shoulder, external rotation with arm at the side was 9° less than the nonoperated side, and 58 (83%) returned to sports at preinjury level. On latest radiographs, 64 (91%) had no osteoarthritis, and bone block positioning was accurate, with 63 (90%) being below the equator and 65 (93%) flush to the glenoid surface. The coracoid graft healed in 51 (73%), it failed to unite in 14 (20%), and graft osteolysis was seen in five (7%). Bone block nonunion/migration did not compromise shoulder stability but was associated with persistent apprehension and less return to sports. Use of screws that were too short or overangulated, smoking, and age higher than 35 years were risk factors for nonunion. CONCLUSIONS: The arthroscopic Bristow-Latarjet procedure combined with Bankart repair for anterior instability with severe glenoid bone loss restored shoulder stability, maintained ROM, allowed return to sports at preinjury level, and had a low likelihood of arthritis. Adequate healing of the transferred coracoid process to the glenoid neck is an important factor for avoiding persistent anterior apprehension. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence

Hemiarthroplasty versus reverse shoulder arthroplasty in 4-part displaced fractures of the proximal humerus: Multicenter retrospective study

Introduction: Complex 4-part fractures of the proximal humerus are one of the most difficult fractures to manage. For several years, reverse total arthroplasty (RSA) has been proposed as an alternative to hemiarthroplasty (HA) when internal fixation is insufficient. The goal of this study was to compare the short and intermediate term results of these 2 different types of arthroplasty. Materials and methods: In a retrospective, multicenter study, 57HA and 41 RSA were reviewed after a follow-up of at least 2 years. The clinical evaluation was based on the absolute and adjusted Constant scores, Simple shoulder value (SSV) and the quick-DASH scores. The radiological assessment included standard radiological tests. Results: After a mean follow-up of 39 months, the RSA group had a significantly higher adjusted Constant score than the HA group (83% vs 73%, respectively P = 0.02). However, there was no significant difference in the absolute Constant score, the quick-DASH or the SSV scores. Active anterior elevation was better in the RSA group, while internal rotation was better in the HA group (130◦ vs 112◦, P = 0.01; sacrum vs L3, P = 0.03). There was no significant difference in external rotation (28◦ vs 23◦, P = 0.31). The rate of complications was higher in the HA group than in the RSA group (24% vs 10%, P = 0.01). The radiological rate of union of the greater tuberosity was similar in both groups (70%) and scapular notching was found in 23% of the RSA group. Conclusion: The short and intermediate term clinical outcomes are better with RSA than with HA. The complication rate is higher with HA. Nevertheless, scapular notching occurred in more than 20% of patients with RSA, suggesting that care should be taken when using this prosthesis in young, active patients

Robustness and Reproducibility of a Glenoid-Centered Scapular Coordinate System Derived From Low-Dose Stereoradiography Analysis

A robust and reproducible scapular coordinate system is necessary to study scapulo-thoracic kinematics. The coordinate system recommended by the ISB (International Society of Biomechanics) is difficult to apply in studies using medical imaging, which mostly use a glenoid-centered coordinate system. The aim of this study was to assess the robustness of a glenoid-centered coordinate system compared to the ISB coordinate system, and to study the reproducibility of this coordinate system measure during abduction. A Monte-Carlo analysis was performed to test the robustness of the two coordinate systems. This method enabled the variability of the orientation of the coordinate system to be assessed in laboratory setting. A reproducibility study of the glenoid-centered coordinate system in the thorax reference frame was performed during abduction in the scapular plane using a low-dose stereoradiography system. We showed that the glenoid-centered coordinate system was slightly more robust than the ISB-recommended coordinate system. Most reproducible rotation was upward/downward rotation (x axis) and most reproducible translation was along the Y axis (superior-inferior translation). In conclusion, the glenoid-centered coordinate system can be used with confidence for scapular kinematics analysis. The uncertainty of the measures derived from our technique is acceptable compared to that reported in the literature. Functional quantitative analysis of the scapular-thoracic joint is possible with this method.We would like to thank Guillaume Simer and Benjamin Aubert for their technical support. Funding: IRSST, ParisTech BiomecAM Chair, Société Générale and Covea

How the greater tuberosity affects clinical outcomes after reverse shoulder arthroplasty for proximal humeral fractures

BACKGROUND: Our purpose was to evaluate the clinical and radiologic outcomes of reverse shoulder arthroplasty for proximal humeral fractures in a large cohort of elderly patients and compare the results in the case of tuberosity excision, failed fixation, or anatomic healing. METHODS: In this retrospective multicenter study, 420 patients underwent review and radiography with a minimum follow-up period of 12 months. The patients were divided into 3 groups according to the status of the greater tuberosity (GT) on the last anteroposterior radiographs: anatomic GT healing (group A, n = 169); GT resorption, malunion, or nonunion (group B, n = 131); and GT excision (group C, n = 120). Complications were recorded; shoulder function, active mobility, and subjective results were assessed. RESULTS: At a mean follow-up of 28 months, the mean Simple Shoulder Value in group A (75%) outperformed the results found in groups B (69%, P < .001) and C (56%, P < .001). Overall, the mean adjusted Constant-Murley score was significantly higher in group A (93% ± 22%) than in group B (82% ± 22%) and group C (80% ± 24%) (P < .001), but there was no difference between groups B and C (P = .88). Anterior active elevation and external rotation were significantly better in group A than in groups B and C (P < .001). The instability rate was significantly higher in group C (n = 15 [12.5%], P < .001) than in group A (n = 2) or group B (n = 3). CONCLUSION: In elderly patients who have undergone a reverse shoulder arthroplasty for acute proximal humeral fractures, anatomic tuberosity healing improves objective and subjective outcomes. GT excision is associated with the worst functional results and increases the risk of postoperative shoulder instability

Three-Dimensional Rotations of the Scapula During Arm Abduction: Evaluation of the Acromion Marker Cluster Method in Comparison With a Model-Based Approach Using Biplanar Radiograph Images

Noninvasive methods enabling measurement of shoulder bone positions are paramount in clinical and ergonomics applications. In this study, the acromion marker cluster (AMC) method is assessed in comparison with a model-based approach allowing scapula tracking from low-dose biplanar radiograph images. Six healthy male subjects participated in this study. Data acquisition was performed for 6 arm abduction positions (0°, 45°, 90°, 120°, 150°, 180°). Scapula rotations were calculated using the coordinate systems and angle sequence was defined by the ISB. The comparison analysis was based on root mean square error (RMSE) calculation and nonparametric statistical tests. RMSE remained under 8° for 0° to 90° arm abduction and under 13.5° for 0° to 180° abduction; no significant differences were found between the 2 methods. Compared with previous works, an improved accuracy of the AMC approach at high arm abduction positions was obtained. This could be explained by the different sources of data used as the "gold standard.

3D scapular orientation on healthy and pathologic subjects using stereoradiographs during arm elevation.

Background Alterations of the scapular kinematics in different pathologic conditions have been widely studied. However, results have shown considerable discrepancies concerning the direction and the amplitude of scapular movement. The lack of consistency in the literature probably has several explanations. The purpose of this study was to analyze scapular orientation with the arm at rest and with 90° lateral elevation in healthy and pathologic subjects by use of stereoradiographs. Materials and methods All participants (n = 65) underwent a clinical examination and magnetic resonance imaging of the shoulder to assess rotator cuff status. Participants were separated into 3 groups: healthy, rotator cuff tear (RCT), and RCT and subacromial impingement syndrome (RCT+ SIS). A 3-dimensional model of the scapula was fitted to each low-dose stereoradiograph acquired with the arm at rest and 90° arm elevation. Results Orientation of the scapula with the arm at rest was not significantly different between groups. During lateral elevation, scapular orientation was not significantly different between the healthy group and the RCT group. However, upward rotation was significantly reduced in the RCT + SIS group. Conclusion Alterations of scapular kinematics in symptomatic subjects are multifactorial. We observed a link between clinically assessed subacromial impingement and scapular orientation during lateral elevation of the arm.Funding: IRSST, ParisTech BiomecAM Chair, Société Générale, and Covea

Inflation on a non-commutative space–time

We study inflation on a non-commutative space–time within the framework of enveloping algebra approach which allows for a consistent formulation of general relativity and of the standard model of particle physics. We show that within this framework, the effects of the non-commutativity of spacetime are very subtle. The dominant effect comes from contributions to the process of structure formation. We describe the bound relevant to this class of non-commutative theories and derive the tightest bound to date of the value of the non-commutative scale within this framework. Assuming that inflation took place, we get a model independent bound on the scale of space–time non-commutativity of the order of 19TeV

Investigation of 3D glenohumeral displacements from 3D reconstruction using biplane X-ray images: Accuracy and reproducibility of the technique and preliminary analysis in rotator cuff tear patients

Rotator cuff (RC) tears may be associated with increased glenohumeral instability; however, this instability is difficult to quantify using currently available diagnostic tools. Recently, the three-dimensional (3D) reconstruction and registration method of the scapula and humeral head, based on sequences of low-dose biplane X-ray images, has been proposed for glenohumeral displacement assessment. This research aimed to evaluate the accuracy and reproducibility of this technique and to investigate its potential with a preliminary application comparing RC tear patients and asymptomatic volunteers. Accuracy was assessed using CT scan model registration on biplane X-ray images for five cadaveric shoulder specimens and showed differences ranging from 0.6 to 1.4 mm depending on the direction of interest. Intra- and interobserver reproducibility was assessed through two operators who repeated the reconstruction of five subjects three times, allowing defining 95% confidence interval ranging from ±1.8 to ±3.6 mm. Intraclass correlation coefficient varied between 0.84 and 0.98. Comparison between RC tear patients and asymptomatic volunteers showed differences of glenohumeral displacements, especially in the superoinferior direction when shoulder was abducted at 20 and 45 . This study thus assessed the accuracy of the low-dose 3D biplane X-ray reconstruction technique for glenohumeral displacement assessment and showed potential in biomechanical and clinical research.Fondation Paris-Tech Programme BIOMECAM Chaire ParisTech Institut de Recherche Robert-Sauvé en Santé et Sécurité du Travail du Québec Natural Science and Engineering Research Council of Canada Fonds de Recherche sur la Nature et les Technologies du Québec Fonds de Recherche en Santé du Québec, EOS Imaging, and French pôle de compétitivité MEDICEN (STEREOS + program)

Analyse morphologique et biomécanique des articulations scapulo-humérale et scapulo-thoracique

Existence of a full thickness rotator cuff tear is really common in the general population with prevalence near 20%. This prevalence increases with age as the existence of asymptomatic cuff tear. How can we explain that tendinous injuries do not cause symptoms?The essential action of the rotator cuff is to center the humeral head in front of the glenoid cavity in order to enable a maximal action of the deltoid muscle. This centering action is still possible in case of supra-spinatus tendon tear and the shoulder can keep a satisfying function if equilibrium is conserved between the anterior cuff (Sub-scapularis muscle) and the posterior cuff (Infra-spinatus and Teres Minor muscles). How can we explain that supra-spinatus tears, even small, can induce functional impairment of the shoulder?There is a real dissociation between anatomy and clinic for the rotator cuff tears and the clinical expression of cuff tears is multifactorial and variable. It depends of the size of the tear and its evolution, of the existence of a sub-acromial bursitis and of the existence of a long head biceps tendinopathy.Comparison between symptomatic and asymptomatic subjects which present a rotator cuff tear permitted to show the importance of the periscapular muscles for the understanding of the rotator cuff tears. Indeed, the function of the periscapular muscles is to orientate the scapula and the glenoid during arm movements. When periscapular muscles are altered, there are anomalies in the scapular orientation which are called scapular dyskinesis.In previous works, we studied the feasibility of pseudo-kinematic studies of the scapula during arm elevation according to the thorax coordinate system derived from low-dose EOS® stereoradiographs. However, this method which was based on the location of specific scapular bony landmarks on each stereoradiographs, presented a low reproducibility and was difficult to use in clinical conditions.The aim of this Thesis was first to optimize this promising method In order to obtain a functional quantitative analysis of the scapula reliable and reproducible. Then, we would like to use this method in-vivo in order to assess the orientation of the scapula during arm elevation on pathologic subjects.L'existence d'une lésion transfixiante de la coiffe des rotateurs est très fréquente dans la population générale avec une prévalence de près de 20%. Cette prévalence augmente avec l'âge tout comme l'existence de lésions asymptomatiques. Comment explique-t-on l'existence de lésions tendineuses qui ne provoquent pas de symptômes ?Le rôle essentiel de la coiffe des rotateurs est de center la tête humérale en face de la glène pour permettre une action optimale du deltoïde. Cette action de centrage est toujours possible en cas de lésion du supra-spinatus et l'épaule peut conserver une fonction satisfaisante à condition que l'équilibre soit conservé entre la coiffe antérieure (Sub-Scapularis) et la coiffe postérieure (Infra-Spinatus et Teres Minor). Comment expliquer alors que des lésions, même petites du supra-épineux peuvent-être à l'origine d'une impotence fonctionnelle de l'épaule ?Il existe une réelle dissociation anatomo-clinique des ruptures de la coiffe des rotateurs et l'expression clinique des lésions de la coiffe est multifactorielle et inconstante. Elle dépend de la taille de la lésion et de son évolutivité, de l'existence d'une bursite sous-acromiale et de l'existence d'une tendinopathie du long biceps.La comparaison de sujets symptomatiques et de sujets asymptomatiques présentant une rupture de coiffe a permis de pointer du doigt l'importance des muscles péri-scapulaires dans la compréhension du retentissement des lésions de coiffe des rotateurs. En effet, ces muscles péri-scapulaires ont pour fonction d'orienter la scapula et la glène lors des mouvements du bras. Lorsque ceux-ci sont altérés, les anomalies d'orientation de la scapula sont appelés dyskinésies scapulaires.Lors de précédents travaux, nous avons étudié la faisabilité d'étude pseudo-cinématique de la scapula par rapport au thorax lors d'un mouvement d'élévation du bras à l'aide de stéréoradiographies basse-dose EOS®. Cependant cette technique basée sur la localisation de points précis de la scapula sur les différentes vues radiographiques s'est montrée peu reproductible et difficile à utiliser en routine clinique.L'objectif de ce travail de Thèse était tout d'abord d'optimiser cette technique d'analyse prometteuse et peu-irradiante afin d'obtenir une analyse fonctionnelle quantitative fiable et reproductible de la scapula. Ensuite, nous avons souhaité utiliser cette technique in-vivo, sur une cohorte de sujets pour évaluer le comportement de la scapula dans différentes situations pathologiques