Reverse Shoulder Arthroplasty Designs Research Articles

Reverse shoulder arthroplasty: Current trend in elective surgery

While reverse shoulder arthroplasty (RSA) is not generally accepted as a successful procedure until recent years, the concept of RSA has long been proposed. Several RSA designs were originally developed for treatment of cuff tear arthropathy (CTA) in the 1970’s, which all underwent in failure. From 1987 to 1995, Paul Grammont and his team proposed successful modern reverse designs of total shoulder arthroplasty for CTA. Medializing and distalizing the center of rotation are the most distinguished principles of Grammont’s RSA. The use of RSA has been increased dramatically over the past decades. The indications for RSA have expanded to massive irrepairable rotator cuff tears, proximal humerus fractures, fracture sequelae, inflammatory arthropathy, osteoarthritis with abnormal glenoid morphology, revision cases following failed shoulder arthroplasty, and tumor reconstruction, in addition to CTA. Contraindications to RSA includes infection, complete axillary nerve palsy, neuroarthropathy, and substantial glenoid bone erosion or defects. The number of complications and reoperations of RSA has been increased significantly with the wide application of RSA. RSA complications can be classified into non-specific complications, specific complications associated with RSA and brand-related specific problems. Glenoid bone loss is not uncommon in patients undergoing RSA, which is a challenging problem. Current methods for addressing glenoid bone loss during RSA include asymmetric reaming, use of a lateralized implant, bone grafting, and use of an augmented baseplate. Three-dimensional imaging preoperative planning software and patient-specific instruments have become commercially available for guidance in the insertion of the glenoid component in RSA in recent years. Surgeons performing RSA should select proper patients, be familiar with new surgical techniques and pay attention to technical details, so that the currently high complication rate of RSA can be reduced.

Stemless Shoulder Arthroplasty: Review of Early Clinical and Radiographic Results.

➢ Stemless anatomic and reverse shoulder arthroplasty designs have been shown to have equivalent short-term clinical outcomes compared with stemmed designs; however, to our knowledge, there have been no published long-term follow-up studies.➢ Radiographic results in the short-term follow-up period show a low prevalence of component loosening, stress shielding, or osteolysis.➢ Stemless arthroplasty requires an accurate humeral-head osteotomy to properly restore humeral anatomy because of the lack of a stem as a guide.➢ There is only 1 design approved by the U.S. Food and Drug Administration (FDA) currently available, to our knowledge, but there are several ongoing Investigational Device Exemption (IDE) studies.

Biomechanical analysis of the humeral tray positioning in reverse shoulder arthroplasty design

Despite the widespread use of reverse total shoulder arthroplasty, the fundamental effects of implant configuration on certain biomechanical outcomes have not been completely elucidated especially for the most innovative prostheses. Aim of this work is to investigate the behaviour of a new reverse shoulder prosthesis, characterized by a humeral tray with a variable offset, designed to increase the range of motion and to reduce the impingement. The purposes of this study were to evaluate the effect of reverse shoulder implant design parameters on the deltoid muscle forces, required to produce abduction, and on the shoulder range of motion, in order to provide a more systematic understanding of the fundamental effects of humeral component positioning on the implant performances. The study has been implemented using virtual prototypes of the shoulder-prosthesis assembly. The shape of the prosthesis has been digitally acquired via a 3D scanner and the CAD models of all the components have been created. Through CT images, 3-dimensional models of the shoulder bones have been reconstructed and assembled with the prosthesis components. Numerical FEM models have been set up in order to evaluate how the abduction force changes depending on the humeral tray offset. Using the virtual prototypes of the shoulder-prosthesis assembly, a range of motion analysis has been carried out by setting up a collision detection analysis in a 3D parametric modeling environment. Different humeral tray positions were investigated and four different motions of the arm were simulated. Obtained results have demonstrated that a suitable positioning of the humeral tray can offer significant biomechanical advantages in terms of range of motion and abduction force.

Effect of lateralized design on muscle and joint reaction forces for reverse shoulder arthroplasty

Manufacturers of reverse shoulder arthroplasty (RSA) implants have recently designed innovative implants to optimize performance in rotator cuff-deficient shoulders. These advancements are not without tradeoffs and can have negative biomechanical effects. The objective of this study was to develop an integrated finite element analysis-kinematic model to compare the muscle forces and joint reaction forces (JRFs) of 3 different RSA designs. A kinematic model of a normal shoulder joint was adapted from the Delft model and integrated with the well-validated OpenSim shoulder model. Static optimizations then allowed for calculation of the individual muscle forces, moment arms, and JRFs relative to net joint moments. Three-dimensional computer models of 3 RSA designs-humeral lateralized design (HLD), glenoid lateralized design, and Grammont design-were integrated, and parametric studies were performed. Overall, there were decreases in deltoid and rotator cuff muscle forces for all 3 RSA designs. These decreases were greatest in the middle deltoid of the HLD model for abduction and flexion and in the rotator cuff muscles under both internal rotation and external rotation. The JRFs in abduction and flexion decreased similarly for all RSA designs compared with the normal shoulder model, with the greatest decrease seen in the HLD model. These findings demonstrate that the design characteristics implicit in these modified RSA prostheses result in mechanical differences most prominently seen in the deltoid muscle and overall JRFs. Further research using this novel integrated model can help guide continued optimization of RSA design and clinical outcomes.

Medialized Versus Lateralized Center of Rotation in Reverse Shoulder Arthroplasty.

Reverse shoulder arthroplasty may be performed using components that medialize or lateralize the center of rotation. The purpose of this prospective study was to directly compare 2 reverse shoulder arthroplasty designs. Two treatment groups and 1 control group were identified. Group I comprised 9 patients using a medialized Grammont-style (GRM) prosthesis with a neck-shaft angle of 155°. Group II comprised 9 patients using a lateralized (LAT) prosthesis with a neck-shaft angle of 135°. Pre- and postoperative assessment of range of motion, American Shoulder and Elbow Surgeons score, and visual analog scale pain score were performed. Radiographic measurements of lateral humeral offset and acromiohumeral distance were compared. The GRM prosthesis achieved greater forward flexion (143.9° vs 115.6°; P=.05), whereas the LAT achieved greater external rotation (35.0° vs 28.3°; P=.07). The lateral humeral offset was greater for the LAT prosthesis compared with the GRM prosthesis, but this distance was not significantly different from that found in the control group. The acromiohumeral distance was significantly greater in the GRM prosthesis group compared with both the LAT and the control groups. The results of this study confirm that different reverse shoulder arthroplasty designs produce radiographically different anatomy. Whereas the GRM prosthesis significantly alters the anatomy of the shoulder, the LAT design can preserve some anatomic relationships found in the normal shoulder. The clinical outcomes indicate that this may have an effect on range of motion, with traditional designs achieving greater forward flexion and lateralized designs achieving greater external rotation.

Effects of the humeral tray component positioning for onlay reverse shoulder arthroplasty design: a biomechanical analysis

Recent shoulder prostheses have introduced a concept of a universal humeral stem component platform that has an onlay humeral tray for the reverse total shoulder arthroplasty (RTSA). No studies have reported how humeral tray positioning can affect the biomechanics of RTSA. The Newcastle Shoulder Model was used to investigate the biomechanical effect of humeral tray positioning in the Biomet Comprehensive Total Shoulder System (Biomet, Warsaw, IN, USA) RTSA. Five humeral tray configuration positions were tested: no offset, and 5 mm offset in the anterior, posterior, medial, and lateral positions. Superior and inferior impingement were evaluated for abduction, scapular plane elevation, forward flexion, and external/internal rotation with the elbow at the side (adduction) and at 90° of shoulder abduction. Muscle lengths and moment arms (elevating and rotational) were calculated for the deltoid, the infraspinatus, the teres minor, and the subscapularis. Inferior impingement was not affected by the humeral tray position. There was less superior impingement during abduction, scapular plane elevation, and rotation with the shoulder when the tray was placed laterally or posteriorly. The subscapularis rotational moment arm was increased with a posterior offset, whereas infraspinatus and teres minor rotational moment arms were increased with an anterior offset. Very little change was observed for the deltoid elevating moment arm or for its muscle length. Positioning the humeral tray with posterior offset offers a biomechanical advantage for patients needing RTSA by decreasing superior impingement and increasing the internal rotational moment arm of the subscapularis, without creating inferior impingement.

A reverse shoulder arthroplasty with increased offset for the treatment of cuff-deficient shoulders with glenohumeral arthritis.

Inherent disadvantages of reverse shoulder arthroplasty designs based on the Grammont concept have raised a renewed interest in less-medialised designs and techniques. The aim of this study was to evaluate the outcome of reverse shoulder arthroplasty (RSA) with the fully-constrained, less-medialised, Bayley-Walker prosthesis performed for the treatment of rotator-cuff-deficient shoulders with glenohumeral arthritis. A total of 97 arthroplasties in 92 patients (53 women and 44 men, mean age 67 years (standard deviation (sd) 10, (49 to 85)) were retrospectively reviewed at a mean follow-up of 50 months ((sd 25) (24 to 96)). The mean Oxford shoulder score and subjective shoulder value improved from 47 (sd 9) and 24 points (sd 18) respectively before surgery to 28 (sd 11) and 61 (sd 24) points after surgery (p < 0.001). The mean pain at rest decreased from 5.3 (sd 2.8) to 1.5 (sd 2.3) (p < 0.001). The mean active forward elevation and external rotation increased from 42(°)(sd 30) and 9(°) (sd 15) respectively pre-operatively to 78(°) (sd 39) and 24(°) (sd 17) post-operatively (p < 0.001). A total of 20 patients required further surgery for complications; 13 required revision of components. No patient developed scapular notching. The Bayley-Walker prosthesis provides reliable pain relief and reasonable functional improvement for patients with symptomatic cuff-deficient shoulders. Compared with other designs of RSA, it offers a modest improvement in forward elevation, but restores external rotation to some extent and prevents scapular notching. A longer follow-up is required to assess the survival of the prosthesis and the clinical performance over time.

Reverse shoulder arthroplasty - a literature review.

Professor Grammont revolutionised shoulder surgery with his reverse shoulder arthroplasty design. Patients who had poor results from a conventional shoulder replacement because of cuff deficiency can now be treated effectively. Although designed for cuff tear arthropathy, indications continue to evolve and broaden. The initial results look very promising and the implant has gained much popularity over the years. The article provides an extensive literature review of the indications, results and complications for reverse shoulder arthroplasty.

The Classic: Delta Shoulder Prosthesis for Rotator Cuff Rupture

We provide a link to the original description of the “delta” reverse shoulder arthroplasty published in 1993 by Paul Grammont and Emmanuel Baulot. While many surgeons view “anatomic reconstruction” as essential for virtually all operations, Grammont recognized that not all reconstructions needed to be anatomic and in fact some problems with so-called anatomic reconstructions could be solved by developing nonanatomic approaches. Through careful reasoning and intuition, Grammont and Baulot suggested placing the ball of the shoulder on the glenoid and the concave matching surface on the humerus in patients with an absent rotator cuff (essentially rendering any anatomic reconstruction “nonanatomic” when the cuff function could not be normally restored). They argued the deltoid muscle could compensate for an absent rotator cuff if four conditions were present: (1) a lever arm effective from the start of movement; (2) a fixed center of rotation; (3) inherent stability; (4) maintenance of adequate external rotation. The result of their reasoning was the Delta Shoulder Prosthesis, the prototype of all other modern reverse shoulder arthroplasty designs. They briefly reported 14 patients with 2-year followup, finding acceptably restored function in 13. (Editor’s Note: The original article had no Abstract; this Abstract was therefore written to provide readers a summary.) The Classic article is © 1993 and is reprinted from Grammont PM, Baulot E. Delta Shoulder Prosthesis for Rotator Cuff Rupture. Orthopedics. 1993;16:65–68 available at http://www.orthosupersite.com/view.aspx?rid=84164. An accompanying biographical sketch of Paul Grammont is available at DOI 10.1007/s11999-011-1959-y.

How Reverse Shoulder Arthroplasty Works

The reverse total shoulder arthroplasty was introduced to treat the rotator cuff-deficient shoulder. Since its introduction, an improved understanding of the biomechanics of rotator cuff deficiency and reverse shoulder arthroplasty has facilitated the development of modern reverse arthroplasty designs. We review (1) the basic biomechanical challenges associated with the rotator cuff-deficient shoulder; (2) the biomechanical rationale for newer reverse shoulder arthroplasty designs; (3) the current scientific evidence related to the function and performance of reverse shoulder arthroplasty; and (4) specific technical aspects of reverse shoulder arthroplasty. A PubMed search of the English language literature was conducted using the key words reverse shoulder arthroplasty, rotator cuff arthropathy, and biomechanics of reverse shoulder arthroplasty. Articles were excluded if the content fell outside of the biomechanics of these topics, leaving the 66 articles included in this review. Various implant design factors as well as various surgical implantation techniques affect stability of reverse shoulder arthroplasty and patient function. To understand the implications of individual design factors, one must understand the function of the normal and the cuff-deficient shoulder and coalesce this understanding with the pathology presented by each patient to choose the proper surgical technique for reconstruction. Several basic science and clinical studies improve our understanding of various design factors in reverse shoulder arthroplasty. However, much work remains to further elucidate the performance of newer designs and to evaluate patient outcomes using validated instruments such as the American Society for Elbow Surgery, simple shoulder test, and the Constant-Murley scores.

Bony Increased-Offset Reverse Shoulder Arthroplasty (BIO-RSA) for Cuff Tear Arthropathy

Given the disappointing results of hemiarthoplasty and the unacceptably high failure rates of total shoulder protheses, reverse shoulder arthroplasty (RSA) has become an attractive treatment option for patients with painful cuff tear arthropathy. Grammont's original medialized design represented a major advance in the restoration of shoulder function for these patients. Scapular notching, prosthetic instability, limited shoulder rotation, and loss of shoulder contour are all problems resulting from the medialization of the center of rotation, stimulating others, in turn, to develop lateralized RSA designs. Rather than changing the geometry of the glenoid prosthesis, our approach to achieving lateralization has been to increase the bony offset of the glenoid. In this article, we present the surgical technique of bony increase-offset reverse shoulder arthroplasty (BIO-RSA). By using a modified base-plate with a lengthened central peg, we place a cancellous bone graft harvested from the humeral head beneath the baseplate of the RSA, effectively creating a long-necked scapula. At a minimum of 2 years after surgery, in a prospective cohort of 42 patients receiving BIO-RSA, there were no cases of glenoid loosening or prosthetic instability. Computed tomography and plain radiographic review demonstrated healing of all glenoid bone grafts. Scapular notches were observed in only 9 cases. Significant improvements were observed when disease-specific outcome measures were used and in all planes of shoulder mobility. BIO-RSA appears as a biological solution to minimize inferior scapular notching and to maximize shoulder stability and mobility without increasing the risk of glenoid component failure. Healing of the humeral bone graft on the native glenoid is consistently observed, allowing the creation of a scapula with a long neck. In contrast to metallic increased-offset, BIO-RSA offers the advantage of maintaining the center of rotation of the joint at the prosthesis-glenoid interface and therefore minimizing torque on the glenoid component.

A history of reverse total shoulder arthroplasty.

Management of the cuff-deficient arthritic shoulder has long been challenging. Early unconstrained shoulder arthroplasty systems were associated with high complication and implant failure rates. The evolution toward the modern reverse shoulder arthroplasty includes many variables of constrained shoulder arthroplasty designs. This review explores the development of reverse shoulder arthroplasty, specifically describing (1) the evolution of reverse shoulder arthroplasty designs, (2) the biomechanical variations in the evolution of this arthroplasty, and (3) the current issues relevant to reverse shoulder arthroplasty today. Using a PubMed search, the literature was explored for articles addressing reverse shoulder arthroplasty, focusing on those papers with historical context. Results of the early designs were apparently poor, although they were not subjected to rigorous clinical research and usually reported only in secondary literature. We identified a trend of glenoid component failure in the early reverse designs. This trend was recognized and reported by authors as the reverse shoulder evolved. Authors reported greater pain relief and better function in reverse shoulder arthroplasty with the fundamental change of Grammont's design (moving the center of rotation medially and distally). However, current reports suggest lingering concerns and challenges with today's designs. The history of reverse shoulder arthroplasty involves the designs of many forward-thinking surgeons. Many of these highly constrained systems failed, although more recent designs have demonstrated improved longevity and implant performance. Reverse shoulder arthroplasty requires ongoing study, with challenges and controversies remaining around present-day designs.