Prosthesis design and placement in reverse total shoulder arthroplasty
© Ackland et al. 2015
Received: 7 January 2015
Accepted: 22 June 2015
Published: 2 July 2015
The management of irreparable rotator cuff tears associated with osteoarthritis of the glenohumeral joint has long been challenging. Reverse total shoulder arthroplasty (RSA) was designed to provide pain relief and improve shoulder function in patients with severe rotator cuff tear arthropathy. While this procedure has been known to reduce pain, improve strength and increase range of motion in shoulder elevation, scapular notching, rotation deficiency, early implant loosening and dislocation have attributed to complication rates as high as 62 %. Patient selection, surgical approach and post-operative management are factors vital to successful outcome of RSA, with implant design and component positioning having a significant influence on the ability of the shoulder muscles to elevate, axially rotate and stabilise the humerus. Clinical and biomechanical studies have revealed that component design and placement affects the location of the joint centre of rotation and therefore the force-generating capacity of the muscles and overall joint mobility and stability. Furthermore, surgical technique has also been shown to have an important influence on clinical outcome of RSA, as it can affect intra-operative joint exposure as well as post-operative muscle function. This review discusses the behaviour of the shoulder after RSA and the influence of implant design, component positioning and surgical technique on post-operative joint function and clinical outcome.
While rotator cuff tear arthropathy remains the primary indication for RSA, applications now include a variety of conditions associated with rotator cuff deficiency or dysfunction. These include cuff tear pseudo-paralysis, tumour resection, revision shoulder arthroplasty [1, 5, 7–10], fracture sequelae [10–12] and, lately, severely comminuted non-reconstructable proximal humerus fractures . Complication rates for RSA are as high as 68 % , with substantially higher complication rates observed in revision surgery [15, 16]. The most common complications observed in RSA are scapular notching, glenohumeral dislocation, component loosening, acromion or spine of scapula facture, infection, nerve injury and deltoid weakness . With reported complication rates associated with RSA higher than those of conventional anatomic replacement [2, 18–20], significant efforts have been made to refine surgical implantation method and prosthesis design. Variables such as neck-shaft angle of the humerus, glenosphere diameter, eccentricity and lateral offset, glenoid base plate tilt and component fixation are known to influence clinical outcome and can vary significantly in different implant designs and surgical approaches .
Reverse shoulder prosthesis rationale and biomechanics
In the natural shoulder, the rotator cuff actively stabilises the glenohumeral joint by compressing the humeral head against the glenoid [22–24]. This is primarily facilitated by a transverse-plane force couple generated by the simultaneous activity of internal rotators (subscapularis, latissimus dorsi) and external rotators (infraspinatus and teres minor). An important function of this force couple is to resist the upward shear force generated by the deltoid, especially during initiation of abduction . In the case of rotator cuff dysfunction, the ability of the musculature to generate concavity compression may be compromised causing the humeral head to translate superiorly under the superior shear force produced by the deltoid. This may eventually result in acetabularisation of the glenoid and acromion arc and superior glenoid wear [26, 27]. Hemiarthroplasty has been an important standard of care in this environment, but offers only ‘limited goals’ for post-operative function [28–32], with pain relief and range of movement unpredictable [33–35]. Constrained prostheses were introduced to exceed these limited goals with little success. While many such designs may have provided effective short-term pain relief, they were not able to withstand the large shear forces transmitted through the upper limb and typically failed at the glenoid-prosthesis interface [17, 31].
Firstly, the humeral cup, oriented at approximately 155° with respect to the long axis of the humerus, covers less than half of the glenosphere . This has the advantage of lowering the humerus, resulting in increased tensioning of the deltoid. However, while greater passive tension in the deltoid may improve deltoid force-generating capacity and joint range of motion, overtensioning of the deltoid may result in fracture of the acromion and reduced shoulder function [37, 38]. Prolonged deltoid overtensioning is also thought to be the cause of mid- to long-term decline in deltoid function.
Secondly, medialisation of the centre of rotation of the glenohumeral joint recruits more fibres of the deltoid during elevation, improving force production and enhancing range of shoulder motion . Thirdly, the glenosphere offers a greater potential arc of movement of the humerus before impingement of the humeral component occurs. Due to the location of the glenohumeral centre of rotation at the glenoid surface, it reduces torque and shear force generated at the glenosphere-bone interface , which is a risk factor for base-plate failure in lateralised glenosphere designs.
Maximum and minimum moment arms of the middle, anterior and posterior sub-regions of the deltoid during scapular-plane abduction, coronal-plane abduction and flexion 
Surgical approach is an important factor in RSA, as it is known to greatly influence post-operative muscle function and therefore clinical outcome . The two most common techniques used are the delto-pectoral approach and the antero-superior deltoid splitting. The delto-pectoral approach minimises damage to the deltoid, which may improve post-operative elevation function and range of motion. In addition, it is thought that this approach allows for greater glenoid exposure therefore improving intra-operative implant positioning. Ultimately, this may influence the surgeon’s judgment of factors such as inferior glenoid tilt and glenoid version, which may contribute to scapular notching and affect post-operative range of motion and joint stability . Unfortunately the delto-pectoral approach is known to compromise the subscapularis and potentially increase risk of joint dislocation [43, 44]. The subscapularis is an important stabiliser of the shoulder joint, opposing the action of the teres minor, and thereby generating compressive joint force by the resultant transverse-plane force couple. Damage to the subscapularis may disrupt this stabilising mechanism, resulting in joint instability.
The antero-superior deltoid splitting approach preserves the integrity of the subscapularis, and therefore may result in better post-operative joint stability. Some reports suggest that this technique yields poor exposure of the glenohumeral joint and thus may lead to a tendency of the surgeon to inadvertently tilt the glenoid base plate superiorly, resulting in intra-operative impingement on the scapula by the proximal humerus . Other reports suggest a tendency for the surgeon to unintentionally resect more of the proximal humerus, which must then compensated for with a larger humeral polyethylene insert in order to obtain stable reduction .
Scapular notching and adduction deficit
Minimisation of scapular notching has been achieved using a more lateralised glenosphere offset and projecting the joint centre of rotation laterally relative to the glenoid face (Fig. 2c). This is the rationale behind the design of Reverse Shoulder Prosthesis (RSP, DJO Surgical, Austin, Texas, USA), which offers increased glenosphere proportions with up to 10 mm of lateral offset. While lateralised implant designs have resulted in lower incidence of notching [18, 49], they have also been associated with higher rates of base plate failure. This is due to the fact that a lateralised glenosphere creates a lever between the joint centre of rotation and the glenoid-baseplate interface, presenting risk of glenosphere failure due to torque transmitted from the upper limb directly to the glenoid baseplate.
Bony increased offset reverse shoulder arthroplasty (BIO RSA) is a technique modification used in conjunction with the Aequalis Reversed Shoulder System (Tornier Inc., Houston, Texas, USA). A discoid piece of bone autograft, generally harvested from the excised humeral head, is introduced between the native glenoid and the glenosphere and secured with use of a specific glenoid base plate (metaglene) incorporating a lengthened central peg . The BIO RSA technique maintains the centre of rotation at the glenoid face but lateralises the entire construct. As a consequence, the torque loads transmitted to the baseplate are potentially lower than those in the lateralised RSP or Arrow designs. The BIO RSA technique may prove useful for primary RSA with marked glenoid wear or in revision RSA with resulting glenoid bone loss.
Neck-shaft angle and effective angle of inclination
Changing the humeral neck-shaft angle from the Grammont standard 155° in the Delta III, to 145° in the Equinoxe (Exactech, Inc., Gainesville, Florida, USA) or to 135° in the RSP, SMR and Comprehensive (Biomet, Warsaw, Indiana), may confer biomechanical advantage and reduce adduction deficit , as the joint centre of rotation is shifted inferiorly.
Implants such as the Zimmer trabecular metal reverse shoulder system (Zimmer, Warsaw, Indiana) have a 5–10° wedged humeral polyethylene insert which can alter the effective angle of inclination; however, a thicker polyethylene liner can produce greater wear debris in the event of impingement and notching.
The eccentric glenosphere
Glenosphere eccentricity may be achieved by shifting the glenosphere centre of rotation without altering the position of the base plate. The SMR, Aequalis, Delta III, Arrow and several other designs offer an eccentric glenosphere option. Clinical studies, mathematical modelling and sawbone-based experiments suggest that inferior eccentricity of the glenosphere may mitigate adduction impingement by shifting the glenohumeral joint centre of rotation inferiorly [51–53]. Eccentricity may also be employed anteriorly or posteriorly in the event of impingement or instability.
In a cadaveric study, Nyffeler and colleagues demonstrated that by placing the metaglene base plate on the inferior glenoid margin rather than in the centre of the glenoid, a glenosphere overhang was created that made impingement far less likely due to the increased space created between the humeral tray and the scapula . This finding was confirmed in a retrospective clinical series by Simovitch  and corroborated in later computer modelling studies which concluded that shifting the metaglene inferiorly was the single most significant factor in mitigating impingement of the scapula [56, 57]. However, Nyffeler highlighted that this inferior shift may be complicated by insufficient distal bone stock in which to secure the obliquely oriented locking screw inferior to the central peg. A potential solution may be seen in the Affinis Inverse which has an additional horizontal peg rather than an inferior oblique screw.
Inferior angulation of the glenosphere
Traditional articular surfaces in the reverse shoulder prostheses have a metal glenosphere and a polyethylene cup insert over the humerus. However, others offer the reverse anatomy components with a polyethylene glenosphere and a metal cup insert over the humerus. Examples of this bearing surface style are the Affinis Inverse (Mathys, Bettiach, Switzerland) and the 40- and 44-mm glenospheres of the Shoulder Modular Replacement SMR (Lima Corporate, San Daniele del Friuli, Italy). This has the theoretical advantage of minimising polyethylene debris if impingement occurs; however, this remains to be proven in long-term clinical studies.
External rotation deficit
Prosthetic reverse shoulder components were developed to function in rotator cuff-deficient shoulders without the typical stabilising transverse-plane force couple produced by the simultaneous activity of the subscapularis, infraspinatus and teres minor. While their non-anatomical constructs shift the joint centre of rotation medially and inferiorly to recruit more fibres of the deltoid during abduction and flexion , biomechanical studies demonstrate that reverse prosthetic designs may shorten the external rotation moment arms of the teres minor and posterior sub-region of the deltoid, thereby reducing external rotation capacity . In a multicenter study, it was shown that 27 % of patients had lost some external rotation compared with their pre-operative state, while 13 % had negative or no external rotation . In a retrospective review of 191 replacements, a mixture of Delta III and Aequalis implants, Wall et al. found no statistical improvement in external rotation at a minimum of 2 years follow-up. When assessed with their arm at their side, the study population had an average of 6° of external rotation, down from 8° pre-operatively . In contrast, elevation is typically improved in RSA by recruitment of the deltoid; in the same study, elevation increased from an average of 86° to 137°. Clinical studies concur that fatty atrophy of the teres minor in RSA results in even greater loss of external rotation movement and poorer clinical outcome scores [9, 16, 62]. In such cases, latissimus dorsi tendon transfer may be used to restore external rotation function .
There is some evidence that lateralised designs may maximise the capacity of rotation movements by maintaining tension in any remaining rotator cuff muscles . This lateralisation has typically been achieved at the glenoid component. However, the Equinoxe and the Arrow have a lateralised centre of rotation not as a result of the glenoid component, but rather a lateralised intra-medullary axis for the humeral component. In this configuration, the polyethylene cup sits on top of the humeral stem in a lateralised position [65, 66]. Hamilton et al. suggest that one should consider RSA components with one of three design philosophies: medialised glenoid and medialised humerus (MGHM), lateralised glenoid and medialised humerus (LGMH, e.g. RSA), or medialised glenoid and lateralised humerus (MGLH, e.g. Equinoxe) . Using a computer model, they suggested a design-dependent increase in moment arms of the external rotators and therefore the potential of a corresponding increase in range of movement for the patient. While this has not been proven clinically, the disability caused by limitation of external rotation at the shoulder is well recognised and an important impairment in performing activities of daily living . Rotation appears to be of particular practical importance during abduction or elevation away from the body. Therefore, reports assessing shoulder axial rotation capacity with the elbow positioned by the side should be interpreted with caution. Sirveaux et al. reported that external rotation assessed with the arm at the side showed no statistical improvement in their 80 cases; however, when measured with the shoulder in 90° of abduction, a significant improvement was demonstrated post-operatively . Their suggested explanation was recruitment of the deltoid with abduction, which in turn aided external rotation.
Humeral version may also play a role in axial rotation. Gulotta et al., in a cadaveric model, investigated the effect of humeral version on muscle recruitment and impingement-free arc of movement . They could not demonstrate any meaningful change in biomechanical muscle force generated in teres minor but found that with increased humeral retroversion, there was an increased range of impingement-free external rotation; however, this was at the expense of internal rotation . Humeral version may simply alter the arc in which the available rotation occurs. While increasing retroversion may delay impingement during external rotation, it may mean that impingement occurs earlier in internal rotation .
A further factor that may contribute to loss of external rotation is inadvertent damage to the suprascapular nerve from malpositioning of baseplate metaglene screws [70, 71]. Penetration of the suprascapular nerve may affect infraspinatus function and therefore external rotation function. While the numbers of screws used in baseplate fixation varies with implant design, from two in the SMR, to four in the Delta III design, and six in the Equinoxe, the screws that present the greatest risk of nerve damage are the superior and, if present, the posterior screws. This is not likely to be a common factor in the determination of external rotation when compared to the pre-operative state of teres minor, the extent of construct medialisation or humeral version, but it is within the control of the operating surgeon and is another example of a design-dependent factor that may influence clinical outcome.
Dislocation was found to be the most common complication of RSA by Wall et al. when they retrospectively reviewed 199 procedures associated with a variety of indications. They identified fifteen dislocations, a prevalence of 7.5 % for their study population . It was also shown that revision procedures present higher risk of dislocation . When reviewing results of RSA for failed fracture hemiarthroplasty, Levy et al. describe dislocation in 5 of 29 patients, 3 of whom experienced recurrent dislocation . Thus, the risk of dislocation may be dependent on the original indication for surgery .
Reconstruction of the subscapularis affects the risk of dislocation in the reverse shoulder . Edwards et al., in a review of 138 consecutive Aequalis implants, identified seven patients who suffered dislocation within 2 months of their operation (5.1 %). All had been identified as having an irreparable tear to the subscapularis at the time of operation. Relative dislocation incidence in those without a subscapularis repair was just 1.9 % . The pre-operative diagnosis of a subscapularis repair was also strongly associated with dislocation incidence, perhaps reflecting the difficulty incurred in repairing the subscapularis.
Humeral version may also play a role in increasing joint stability post-operatively. Using a mechanical model, Favre et al. found that increasing glenoid retroversion produced glenohumeral instability, whereas increasing anteversion of the humerus produced greater stability by joint compression . They concluded that glenoid retroversion of more than 10° should be avoided and that humeral version should be neutral or slightly anteverted due to the negative effect on external rotation range of motion. Inferior glenoid inclination has also been suggested as mechanism to reduce dislocation. In a retrospective study, Randelli et al. describe a cohort of 33 patients all of whom underwent RSA with a Delta Xtend reverse prosthesis with varying degrees of glenoid tilt. Two atraumatic dislocations occurred (6 %) within the first 2 months. One had a positive inclination of 6.9° and the other a negative of 2.4°. All stable implants had an average negative inclination of 9.4° . While these results suggest a dislocation protection effect with inferior inclination, further prospective studies are required to explore this association and its effect on glenohumeral joint compression.
RSA is an evolving technique. Indications for surgery, operative technique, implant design and the avoidance of complication are dependent on fundamental principles of biomechanics. Surgical technique and prosthesis design can have a significant influence on clinical outcome of RSA and implant longevity. Scapular notching and external rotation deficit are predominantly influenced by joint centre of rotation position and post-operative muscle leverage, respectively. These factors can vary substantially with implant design. While short-term results of RSA remain positive, especially in cases of difficult to treat pathologies such as cuff tear arthropathy, uniformly satisfactory long-term results are yet to be achieved. Scope for future research and prosthetic design development lie in a better understanding of the influence of optimum bearing surfaces, glenoid diameters, implant version, inclination and offset and their effect on muscle and joint function, since these design parameters are highly relevant to clinical outcome.
- Grammont PM, Trouilloud P, Laffay JP, Deries X. Etude et réalisation d’une nouvelle prosthèse d’épaule. Rhumatologie. 1987;10:407–18.Google Scholar
- Boileau P, Watkinson DJ, Hatzidakis AM, Balg F. Grammont reverse prosthesis: design, rationale, and biomechanics. J Shoulder Elbow Surg. 2005;14(1 Suppl S):147S–61S.View ArticlePubMedGoogle Scholar
- Flatow EL, Harrison AK. A history of reverse total shoulder arthroplasty. Clin Orthop Relat Res. 2011;469(9):2432–9.View ArticlePubMed CentralPubMedGoogle Scholar
- Katz D, O’Toole G, Cogswell L, Sauzieres P, Valenti P. A history of the reverse shoulder prosthesis. Int J Shoulder Surg. 2007;1:108–13.View ArticleGoogle Scholar
- Rockwood Jr CA. The reverse total shoulder prosthesis. The new kid on the block. J Bone Joint Surg Am. 2007;89(2):233–5.View ArticlePubMedGoogle Scholar
- Schrumpf MA, Kristofer JJ, Dines DM. Reverse total shoulder arthroplasty: restoring function. Semin Arthroplasty. 2012;23:83–9.View ArticleGoogle Scholar
- Baulot E, Chabernaud D, Grammont PM. Results of Grammont’s inverted prosthesis in omarthritis associated with major cuff destruction. Apropos of 16 cases. Acta Orthop Belg. 1995;61 Suppl 1:112–9.PubMedGoogle Scholar
- Jacobs R, Debeer P, De Smet L. Treatment of rotator cuff arthropathy with a reversed Delta shoulder prosthesis. Acta Orthop Belg. 2001;67(4):344–7.PubMedGoogle Scholar
- Wall B, Nove-Josserand L, O’Connor DP, Edwards TB, Walch G. Reverse total shoulder arthroplasty: a review of results according to etiology. J Bone Joint Surg Am. 2007;89(7):1476–85.View ArticlePubMedGoogle Scholar
- Boileau P, Watkinson D, Hatzidakis AM, Hovorka I. Neer Award 2005: the Grammont reverse shoulder prosthesis: results in cuff tear arthritis, fracture sequelae, and revision arthroplasty. J Shoulder Elbow Surg. 2006;15(5):527–40.View ArticlePubMedGoogle Scholar
- Boileau P, Trojani C, Walch G, Krishnan SG, Romeo A, Sinnerton R. Shoulder arthroplasty for the treatment of the sequelae of fractures of the proximal humerus. J Shoulder Elbow Surg. 2001;10(4):299–308.View ArticlePubMedGoogle Scholar
- Boulahia A, Edwards TB, Walch G, Baratta RV. Early results of a reverse design prosthesis in the treatment of arthritis of the shoulder in elderly patients with a large rotator cuff tear. Orthopedics. 2002;25(2):129–33.PubMedGoogle Scholar
- Patel M, Nara K, Nara N, Bonato L. Primary reverse total shoulder arthroplasty for proximal humerus fractures in patients over the age of seventy. J Bone Joint Surg Br. 2012;94(Supp XXIII):161.Google Scholar
- Wierks C, Skolasky RL, Ji JH, McFarland EG. Reverse total shoulder replacement: intraoperative and early postoperative complications. Clin Orthop Relat Res. 2009;467(1):225–34.View ArticlePubMed CentralPubMedGoogle Scholar
- Matsen 3rd FA, Boileau P, Walch G, Gerber C, Bicknell RT. The reverse total shoulder arthroplasty. J Bone Joint Surg Am. 2007;89(3):660–7.PubMedGoogle Scholar
- Werner CM, Steinmann PA, Gilbart M, Gerber C. Treatment of painful pseudoparesis due to irreparable rotator cuff dysfunction with the Delta III reverse-ball-and-socket total shoulder prosthesis. J Bone Joint Surg Am. 2005;87(7):1476–86.View ArticlePubMedGoogle Scholar
- Bohsali KI, Wirth MA, Rockwood Jr CA. Complications of total shoulder arthroplasty. J Bone Joint Surg Am. 2006;88(10):2279–92.View ArticlePubMedGoogle Scholar
- Frankle M, Siegal S, Pupello D, Saleem A, Mighell M, Vasey M. The Reverse Shoulder Prosthesis for glenohumeral arthritis associated with severe rotator cuff deficiency. A minimum two-year follow-up study of sixty patients. J Bone Joint Surg Am. 2005;87(8):1697–705.View ArticlePubMedGoogle Scholar
- Boileau P, Gonzalez JF, Chuinard C, Bicknell R, Walch G. Reverse total shoulder arthroplasty after failed rotator cuff surgery. J Shoulder Elbow Surg. 2009;18(4):600–6.View ArticlePubMedGoogle Scholar
- Sirveaux F, Favard L, Oudet D, Huquet D, Walch G, Mole D. Grammont inverted total shoulder arthroplasty in the treatment of glenohumeral osteoarthritis with massive rupture of the cuff. Results of a multicentre study of 80 shoulders. J Bone Joint Surg Br. 2004;86(3):388–95.View ArticlePubMedGoogle Scholar
- Roche CP, Diep P, Hamilton M, Crosby LA, Flurin PH, Wright TW, et al. Impact of inferior glenoid tilt, humeral retroversion, bone grafting, and design parameters on muscle length and deltoid wrapping in reverse shoulder arthroplasty. Bull Hosp Jt Dis (2013). 2013;71(4):284–93.Google Scholar
- Ackland DC, Pandy MG. Lines of action and stabilizing potential of the shoulder musculature. J Anat. 2009;215:184–97.View ArticlePubMed CentralPubMedGoogle Scholar
- Bigliani LU, Kelkar R, Flatow EL, Pollock RG, Mow VC. Glenohumeral stability. Biomechanical properties of passive and active stabilizers. Clin Orthop. 1996;330:13–30.View ArticlePubMedGoogle Scholar
- Lippitt SB, Vanderhooft JE, Harris SL, Sidles JA, Harryman 2nd DT, Matsen 3rd FA. Glenohumeral stability from concavity-compression: a quantitative analysis. Journal of Shoulder and Elbow Surgery. 1993;2:27–35.View ArticlePubMedGoogle Scholar
- Kronberg M, Nemeth G, Brostrom LA. Muscle activity and coordination in the normal shoulder. An electromyographic study. Clin Orthop. 1990;257:76–85.PubMedGoogle Scholar
- Fenlin Jr JM. Total glenohumeral joint replacement. Orthop Clin North Am. 1975;6(2):565–83.PubMedGoogle Scholar
- Franklin JL, Barrett WP, Jackins SE, Matsen 3rd FA. Glenoid loosening in total shoulder arthroplasty. Association with rotator cuff deficiency. J Arthroplasty. 1988;3(1):39–46.View ArticlePubMedGoogle Scholar
- Levine WN, Djurasovic M, Glasson JM, Pollock RG, Flatow EL, Bigliani LU. Hemiarthroplasty for glenohumeral osteoarthritis: results correlated to degree of glenoid wear. J Shoulder Elbow Surg. 1997;6(5):449–54.View ArticlePubMedGoogle Scholar
- Neer 2nd CS, Watson KC, Stanton FJ. Recent experience in total shoulder replacement. J Bone Joint Surg Am. 1982;64(3):319–37.PubMedGoogle Scholar
- Pearl ML, Romeo AA, Wirth MA, Yamaguchi K, Nicholson GP, Creighton RA. Decision making in contemporary shoulder arthroplasty. Instr Course Lect. 2005;54:69–85.PubMedGoogle Scholar
- Post M, Haskell SS, Jablon M. Total shoulder replacement with a constrained prosthesis. J Bone Joint Surg Am. 1980;62(3):327–35.PubMedGoogle Scholar
- Young SW, Zhu M, Walker CG, Poon PC. Comparison of functional outcomes of reverse shoulder arthroplasty with those of hemiarthroplasty in the treatment of cuff-tear arthropathy: a matched-pair analysis. J Bone Joint Surg Am. 2013;95(10):910–5.View ArticlePubMedGoogle Scholar
- Neer 2nd CS, Craig EV, Fukuda H. Cuff-tear arthropathy. J Bone Joint Surg Am. 1983;65(9):1232–44.PubMedGoogle Scholar
- Williams Jr GR, Rockwood Jr CA. Hemiarthroplasty in rotator cuff-deficient shoulders. J Shoulder Elbow Surg. 1996;5(5):362–7.View ArticlePubMedGoogle Scholar
- Zuckerman JD, Scott AJ, Gallagher MA. Hemiarthroplasty for cuff tear arthropathy. J Shoulder Elbow Surg. 2000;9(3):169–72.View ArticlePubMedGoogle Scholar
- Ackland DC, Roshan-Zamir S, Richardson M, Pandy MG. Moment arms of the shoulder musculature after reverse total shoulder arthroplasty. J Bone Joint Surg Am. 2010;92(5):1221–30.View ArticlePubMedGoogle Scholar
- Hamid N, Connor PM, Fleischli JF, D’Alessandro DF. Acromial fracture after reverse shoulder arthroplasty. Am J Orthop (Belle Mead NJ). 2011;40(7):E125–9.PubMedGoogle Scholar
- Wahlquist TC, Hunt AF, Braman JP. Acromial base fractures after reverse total shoulder arthroplasty: report of five cases. J Shoulder Elbow Surg. 2011;20(7):1178–83.View ArticlePubMedGoogle Scholar
- Grammont PM, Baulot E. Delta shoulder prosthesis for rotator cuff rupture. Orthopedics. 1993;16(1):65–8.PubMedGoogle Scholar
- Kontaxis A, Johnson GR. The biomechanics of reverse anatomy shoulder replacement—a modelling study. Clin Biomech (Bristol, Avon). 2009;24(3):254–60.View ArticleGoogle Scholar
- Ackland DC, Richardson M, Pandy MG. Axial rotation moment arms of the shoulder musculature after reverse total shoulder arthroplasty. J Bone Joint Surg Am. 2012;94(20):1886–95.View ArticlePubMedGoogle Scholar
- Hsu SH, Greiwe RM, Saifi C, Hahmad CS. Reverse total shoulder arthroplasty—biomechanics and rationale. Oper Tech Orthop. 2011;21:52–9.View ArticleGoogle Scholar
- Mole D, Wein F, Dezaly C, Valenti P, Sirveaux F. Surgical technique: the anterosuperior approach for reverse shoulder arthroplasty. Clin Orthop Relat Res. 2011;469(9):2461–8.View ArticlePubMed CentralPubMedGoogle Scholar
- Chalmers PN, Rahman Z, Romeo AA, Nicholson GP. Early dislocation after reverse total shoulder arthroplasty. J Shoulder Elbow Surg. 2014;23(5):737–44.View ArticlePubMedGoogle Scholar
- Clouthier AL, Hetzler MA, Fedorak G, Bryant JT, Deluzio KJ, Bicknell RT. Factors affecting the stability of reverse shoulder arthroplasty: a biomechanical study. J Shoulder Elbow Surg. 2013;22(4):439–44.View ArticlePubMedGoogle Scholar
- Ladermann A, Lubbeke A, Collin P, Edwards TB, Sirveaux F, Walch G. Influence of surgical approach on functional outcome in reverse shoulder arthroplasty. Orthop Traumatol Surg Res. 2011;97(6):579–82.View ArticlePubMedGoogle Scholar
- Seebauer L. Reverse prosthesis through a superior approach for cuff tear arthropathy. Tech Shoulder Elbow Surg. 2006;7(1):13–26.View ArticleGoogle Scholar
- Levigne C, Boileau P, Favard L, Garaud P, Mole D, Sirveaux F, et al. Scapular notching in reverse shoulder arthroplasty. J Bone Joint Surg br. 2009;91-B(SUPP II):261.Google Scholar
- Kalouche I, Sevivas N, Wahegaonker A, Sauzieres P, Katz D, Valenti P. Reverse shoulder arthroplasty: does reduced medialisation improve radiological and clinical results? Acta Orthop Belg. 2009;75(2):158–66.PubMedGoogle Scholar
- Gutierrez S, Comiskey CA, Luo ZP, Pupello DR, Frankle MA. Range of impingement-free abduction and adduction deficit after reverse shoulder arthroplasty. Hierarchy of surgical and implant-design-related factors. J Bone Joint Surg Am. 2008;90(12):2606–15.View ArticlePubMedGoogle Scholar
- Chou J, Malak SF, Anderson IA, Astley T, Poon PC. Biomechanical evaluation of different designs of glenospheres in the SMR reverse total shoulder prosthesis: range of motion and risk of scapular notching. J Shoulder Elbow Surg. 2009;18(3):354–9.View ArticlePubMedGoogle Scholar
- Mizuno N, Denard PJ, Raiss P, Walch G. The clinical and radiographical results of reverse total shoulder arthroplasty with eccentric glenosphere. Int Orthop. 2012;36(8):1647–53.View ArticlePubMed CentralPubMedGoogle Scholar
- Poon PC, Chou J, Young SW, Astley T. A comparison of concentric and eccentric glenospheres in reverse shoulder arthroplasty: a randomized controlled trial. J Bone Joint Surg Am. 2014;96(16):e138.View ArticlePubMedGoogle Scholar
- Nyffeler RW, Werner CM, Gerber C. Biomechanical relevance of glenoid component positioning in the reverse Delta III total shoulder prosthesis. J Shoulder Elbow Surg. 2005;14(5):524–8.View ArticlePubMedGoogle Scholar
- Simovitch RW, Zumstein MA, Lohri E, Helmy N, Gerber C. Predictors of scapular notching in patients managed with the Delta III reverse total shoulder replacement. J Bone Joint Surg Am. 2007;89(3):588–600.View ArticlePubMedGoogle Scholar
- de Wilde LF, Poncet D, Middernacht B, Ekelund A. Prosthetic overhang is the most effective way to prevent scapular conflict in a reverse total shoulder prosthesis. Acta Orthop. 2010;81(6):719–26.View ArticlePubMed CentralPubMedGoogle Scholar
- Gutierrez S, Levy JC, Frankle MA, Cuff D, Keller TS, Pupello DR, et al. Evaluation of abduction range of motion and avoidance of inferior scapular impingement in a reverse shoulder model. J Shoulder Elbow Surg. 2008;17(4):608–15.View ArticlePubMedGoogle Scholar
- Edwards TB, Trappey GJ, Riley C, O’Connor DP, Elkousy HA, Gartsman GM. Inferior tilt of the glenoid component does not decrease scapular notching in reverse shoulder arthroplasty: results of a prospective randomized study. J Shoulder Elbow Surg. 2012;21(5):641–6.View ArticlePubMedGoogle Scholar
- Kempton LB, Balasubramaniam M, Ankerson E, Wiater JM. A radiographic analysis of the effects of glenosphere position on scapular notching following reverse total shoulder arthroplasty. J Shoulder Elbow Surg. 2011;20(6):968–74.View ArticlePubMedGoogle Scholar
- Gutierrez S, Walker M, Willis M, Pupello DR, Frankle MA. Effects of tilt and glenosphere eccentricity on baseplate/bone interface forces in a computational model, validated by a mechanical model, of reverse shoulder arthroplasty. J Shoulder Elbow Surg. 2011;20(5):732–9.View ArticlePubMedGoogle Scholar
- Mole D, Favard L. Excentered scapulohumeral osteoarthritis. Rev Chir Orthop Reparatrice Appar Mot. 2007;93(6 Suppl):37–94.View ArticlePubMedGoogle Scholar
- Flury MP, Frey P, Goldhahn J, Schwyzer HK, Simmen BR. Reverse shoulder arthroplasty as a salvage procedure for failed conventional shoulder replacement due to cuff failure—midterm results. Int Orthop. 2011;35(1):53–60.View ArticlePubMed CentralPubMedGoogle Scholar
- Favre P, Loeb MD, Helmy N, Gerber C. Latissimus dorsi transfer to restore external rotation with reverse shoulder arthroplasty: a biomechanical study. J Shoulder Elbow Surg. 2008;17(4):650–8.View ArticlePubMedGoogle Scholar
- Greiner S, Schmidt C, Konig C, Perka C, Herrmann S. Lateralized reverse shoulder arthroplasty maintains rotational function of the remaining rotator cuff. Clin Orthop Relat Res. 2013;471(3):940–6.View ArticlePubMed CentralPubMedGoogle Scholar
- Routman HD. The role of subscapularis repair in reverse total shoulder arthroplasty. Bull Hosp Jt Dis (2013). 2013;71 Suppl 2:108–12.Google Scholar
- Hamilton MA, Roche CP, Diep P, Flurin PH, Routman HD. Effect of prosthesis design on muscle length and moment arms in reverse total shoulder arthroplasty. Bull Hosp Jt Dis (2013). 2013;71 Suppl 2:S31–5.Google Scholar
- Langer JS, Sueoka SS, Wang AA. The importance of shoulder external rotation in activities of daily living: improving outcomes in traumatic brachial plexus palsy. J Hand Surg Am. 2012;37(7):1430–6.View ArticlePubMedGoogle Scholar
- Gulotta LV, Choi D, Marinello P, Knutson Z, Lipman J, Wright T, et al. Humeral component retroversion in reverse total shoulder arthroplasty: a biomechanical study. J Shoulder Elbow Surg. 2012;21(9):1121–7.View ArticlePubMedGoogle Scholar
- Berhouet J, Garaud P, Favard L. Influence of glenoid component design and humeral component retroversion on internal and external rotation in reverse shoulder arthroplasty: a cadaver study. Orthop Traumatol Surg Res. 2013;99(8):887–94.View ArticlePubMedGoogle Scholar
- Hart ND, Clark JC, Wade Krause FR, Kissenberth MJ, Bragg WE, Hawkins RJ. Glenoid screw position in the Encore Reverse Shoulder Prosthesis: an anatomic dissection study of screw relationship to surrounding structures. J Shoulder Elbow Surg. 2013;22(6):814–20.View ArticlePubMedGoogle Scholar
- Molony DC, Cassar Gheiti AJ, Kennedy J, Green C, Schepens A, Mullett HJ. A cadaveric model for suprascapular nerve injury during glenoid component screw insertion in reverse-geometry shoulder arthroplasty. J Shoulder Elbow Surg. 2011;20(8):1323–7.View ArticlePubMedGoogle Scholar
- Levy JC, Virani N, Pupello D, Frankle M. Use of the reverse shoulder prosthesis for the treatment of failed hemiarthroplasty in patients with glenohumeral arthritis and rotator cuff deficiency. J Bone Joint Surg Br. 2007;89(2):189–95.View ArticlePubMedGoogle Scholar
- Edwards TB, Williams MD, Labriola JE, Elkousy HA, Gartsman GM, O’Connor DP. Subscapularis insufficiency and the risk of shoulder dislocation after reverse shoulder arthroplasty. J Shoulder Elbow Surg. 2009;18(6):892–6.View ArticlePubMedGoogle Scholar
- Favre P, Sussmann PS, Gerber C. The effect of component positioning on intrinsic stability of the reverse shoulder arthroplasty. J Shoulder Elbow Surg. 2010;19(4):550–6.View ArticlePubMedGoogle Scholar
- Randelli P, Randelli F, Arrigoni P, Ragone V, D’Ambrosi R, Masuzzo P, et al. Optimal glenoid component inclination in reverse shoulder arthroplasty. How to improve implant stability. Musculoskelet Surg. 2014;98 Suppl 1:15–8.View ArticleGoogle Scholar
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