Lateralization in reverse shoulder arthroplasty: a descriptive analysis of different implants in current practice

Optimizing range of motion in reverse shoulder arthroplasty

Aims

Optimal glenoid positioning in reverse shoulder arthroplasty (RSA) is crucial to provide impingement-free range of motion (ROM). Lateralization and inclination correction are not yet systematically used. Using planning software, we simulated the most used glenoid implant positions. The primary goal was to determine the configuration that delivers the best theoretical impingement-free ROM.

Methods

With the use of a 3D planning software (Blueprint) for RSA, 41 shoulders in 41 consecutive patients (17 males and 24 females; means age 73 years (SD 7)) undergoing RSA were planned. For the same anteroposterior positioning and retroversion of the glenoid implant, four different glenoid baseplate configurations were used on each shoulder to compare ROM: 1) no correction of the RSA angle and no lateralization (C-L-); 2) correction of the RSA angle with medialization by inferior reaming (C+M+); 3) correction of the RSA angle without lateralization by superior compensation (C+L-); and 4) correction of the RSA angle and additional lateralization (C+L+). The same humeral inlay implant and positioning were used on the humeral side for the four different glenoid configurations with a 3 mm symmetric 135° inclined polyethylene liner.

Results

The configuration with lateralization and correction of the RSA angle (C+L+) led to better ROM in flexion, extension, adduction, and external rotation (p ≤ 0.001). Only internal rotation was not significantly different between groups (p = 0.388). The configuration where correction of the inclination was done by medialization (C+M+) led to the worst ROM in adduction, extension, abduction, flexion, and external rotation of the shoulder.

Conclusion

Our software study shows that, when using a 135° inlay reversed humeral implant, correcting glenoid inclination (RSA angle 0°) and lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM.

Reverse shoulder arthroplasty or nothing for patients with displaced proximal humeral fractures: a randomized controlled trial

BACKGROUND

The benefits of reverse shoulder arthroplasty compared to nonoperative treatment for patients presenting with complex proximal fractures have been rarely explored. The aim of this prospective study was to compare the functional results of reverse shoulder arthroplasty with those of nonsurgical treatment in patients with displaced proximal humeral fractures.

METHODS

A multicentric prospective randomized control trial of patients older than 70 years who sustained an acute proximal humeral fracture (3 or 4 parts), with less than 3 weeks of evolution, and had no previous condition or surgery on the affected shoulder was conducted. Patients were randomly assigned to the intervention group (implantation of a reverse shoulder arthroplasty and tuberosities reattachment) or the control group (nonoperative treatment). Functional outcome was assessed using the Constant-Murley score (CMS) at the 1-year follow-up. Complications and reinterventions were considered secondary outcomes. The power of the study relied on the inclusion of 81 patients to recognize a statistically significant difference of 10 points between CMS scores in the groups. Analysis was performed based on the intention to treat principle.

RESULTS

Eighty-one patients were randomized to surgical treatment or nonoperative treatment, while 66 patients completed the 1-year follow-up evaluation. There was no significant difference between the groups in terms of age (76.1 yo vs. 77.43 yo, P = .43), sex (81.08% women in the surgical group vs. 84.09% in the nonoperative group, P = .72), or type of fracture according to Neer's classification system (P = .06). At the 1-year follow-up, the group assigned to undergo the intervention had better functional outcomes than the nonoperative treatment group (mean CMS; 61.24, SD: 13.33 vs. mean CMS: 52.44, SD: 16.22, P: .02), with a mean difference of 8.84 points, 95% CI (1.57, 16.11). Two patients in the intervention group (6.5%) suffered major complications (periprosthetic joint infection and axillary nerve palsy). No major complications were observed in the nonoperative group. One patient in the intervention group underwent secondary surgery for a periprosthetic joint infection.

CONCLUSIONS

Treatment with reverse shoulder arthroplasty provides superior functional outcomes compared with conservative treatment for patients presenting with an acute proximal humeral fracture. The difference in CMS is close to the clinically significant thresholds, and some harms are associated with the operative treatment.

The effect of tuberosity healing on functional outcomes after reverse shoulder arthroplasty for proximal humerus fractures: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis compared clinical outcome measures in patients undergoing reverse shoulder arthroplasty (RSA) for proximal humerus fracture (PHF) with healed versus non-healed greater tuberosity (GT).

METHODS

We performed a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines querying PubMed/MEDLINE, EMBASE, Web of Science, and Cochrane for studies that stratified results by the GT healing status. Studies that did not attempt to repair the GT were excluded. We extracted and compared clinical outcomes including postoperative forward flexion (FF), external rotation (ER), internal rotation (IR), Constant score, and complications and revision rates.

RESULTS

Of the included patients, 295 (78.5%) demonstrated GT healing while 81 did not (21.5%). The healed GT cohort exhibited increased postoperative FF (P < .001), ER (P < .001), IR (P = .006), and Constant score (P = .006) compared to the non-healed GT cohort. The overall dislocation rate was 0.8% with no study differentiating GT status of dislocation cases.

CONCLUSION

Healing of the GT after RSA for PHF yields improved postoperative range of motion and strength, whereas patient-reported pain and function were largely not affected by GT healing indicating merit to RSA for PHF regardless of the likelihood of the GT healing.

Instability after reverse shoulder arthroplasty: a retrospective review of thirty one cases

PURPOSE

A retrospectively analyze of instability after RSA in terms of aetiology, treatment and final functional outcome.

METHODS

A bicentric retrospective study of 31 patients (mean age 67.6 years; 42-83) treated for RSA instability using RSA Arrow System (FH Orthopedics, Mulhouse, France), mean follow-up 41months (range 12-158). Aetiologies for dislocation were evaluated using a previously described classification system for RSA instability. Actions performed during the Revision Surgeries were analyzed and grouped into five categories. Clinical outcome measures included range of motion, SSV, VAS, Constant-Murley scores, satisfaction level and recurrence of instability.

RESULTS

The most frequent aetiology for RSA instability was loss of compression (18), followed by impingement (8) and loss containment (5). Total RSA revision (bipolar procedure) involving both distalization and lateralization occurred in 13 instances. Isolated distalization through the humerus was performed in ten patients and Isolated lateralization through the glenoid in three patients. Three cases of components exchange due to mechanical failure were noted. Bone graft was used in nine instances. Three patients (10%) suffered recurrent instability following Revision Surgery and required an additional stabilizing procedure. At final follow-up all 31 RSA were reported as stable with a mean VAS of 1.1, SSV 54.5%, constant score 48.3, constant ponderate 74.9%.

CONCLUSION

The management of unstable RSA represent a challenge that can be successfully overcome with a revision surgery with compromised functional results. Loss of compression was the most common cause for primary and recurrent RSA instability that were treated principally with bipolar revisions involving component lateralization and distalization.

A gender and size specific evaluation of Grammont-type inlay versus lateralizing onlay stem designs in achieving lateralization and distalization in reverse shoulder arthroplasty

INTRODUCTION

In reverse shoulder arthroplasty (RSA) new designs enable greater amounts of lateralization to prevent instability and scapular notching and increase range of motion, however, excessive lateralization leads to stress upon the acromion that can result in scapular spine fatigue fractures. Aim of this study was to gender- and size-specifically assess the influence of glenosphere size and different humeral designs on lateralization, distalization, and bony impingement-free range of motion (ROM) in patients undergoing RSA.

METHODS

Computed tomography scans from 30 osteoarthritic patients (f:15, m:15) and 20 cuff tear arthropathy patients (f:10, m:10) were used to virtually simulate RSA implantation. The efficacy of an inlay Grammont-type system vs. an onlay lateralizing system combined with different glenosphere sizes (36 mm vs. 42 mm) in achieving ROM, lateralization, and distalization was evaluated. Moreover, gender and patient's constitution were correlated to humeral size by radiologically measuring the best-fit circle of the humeral head.

RESULTS

A different amount of relative lateralization was achieved in both genders using large glenospheres and onlay designs. Latter yielded a higher ROM in all planes for men and women with a 42 mm glenosphere; with the 36 mm glenosphere, an increased ROM was observed only in men. The 155° inlay design led to joint medialization only in men, whereas all designs led to lateralization in women. When adjusting the absolute amount of lateralization to humerus' size (or patient's height), regardless of implant type, women received greater relative lateralization using 36 mm glenosphere (inlay: 1%; onlay 12%) than men with 42 mm glenosphere (inlay: -3%; onlay: 8%).

CONCLUSION

The relative lateralization achieved using onlay design is much higher in women than men. Small glenospheres yield greater relative lateralization in women compared to large glenospheres in men. Humeral lateralization using onlay designs should be used cautiously in women, as they lead to great relative lateralization increasing stress onto the acromion.

LEVEL OF EVIDENCE

Basic Science Study, Computer Modeling.

Does preoperative forward elevation weakness affect clinical outcomes in anatomic or reverse total shoulder arthroplasty patients with glenohumeral osteoarthritis and intact rotator cuff?

BACKGROUND

This study sought to determine if preoperative forward elevation (FE) weakness affects outcomes of anatomic (aTSA) and reverse total shoulder arthroplasty (rTSA) for patients with rotator cuff-intact glenohumeral osteoarthritis (RCI-GHOA).

METHODS

A retrospective review of a single institution's prospectively collected shoulder arthroplasty database was performed between 2007 and 2020, including 333 aTSAs and 155 rTSAs for primary RCI-GHOA with a minimum 2-year follow-up. Defining preoperative weakness as FE strength ≤4.9 lb (2.2 kg), three cohorts were matched 1:1:1 by age, sex, and follow-up: weak (n=82) to normal aTSAs, weak (n=44) to normal rTSAs, and weak aTSAs (n=61) to weak rTSAs. Compared outcomes included range of motion, outcome scores, and complication and revision rates at latest follow-up.

RESULTS

Weak aTSAs and weak rTSAs achieved similar postoperative outcome measures to normal aTSAs and normal rTSAs, respectively (P>0.05). Compared to weak rTSAs, weak aTSAs achieved superior postoperative passive (P=0.006) and active external rotation (ER) (P=0.014) but less favorable postoperative Shoulder Pain and Disability Index (P=0.032), American Shoulder and Elbow Surgeons (P=0.024), and University of California, Los Angeles scores (P=0.008). Weak aTSAs achieved the minimal clinically important difference and substantial clinical benefit at a lower rate for abduction (P=0.045 and P=0.003) and FE (P=0.011 and P=0.001). Weak aTSAs had a higher revision rate (P=0.025) but a similar complication rate (P=0.291) compared to weak rTSAs.

CONCLUSIONS

Patients with RCI-GHOA and preoperative FE weakness obtain postoperative outcomes similar to patients with normal preoperative strength after either aTSA or rTSA. Preoperatively, weak aTSAs achieved greater ER but lower rates of clinically relevant improvement in overhead motion compared to weak rTSAs. Level of evidence: III.

Insertion sites of latissimus dorsi tendon transfer performed during reverse shoulder arthroplasty: A systematic review and meta-analysis

BACKGROUND

Reverse shoulder arthroplasty (RSA) with concurrent latissimus dorsi transfer (LDT) is a potential treatment option for restoration of external rotation (ER). Biomechanical studies have emphasized the importance of the insertion site location for achieving optimal outcomes. In this systematic review and meta-analysis, we aimed to describe what insertion sites for LDT are utilized during concomitant RSA and their associated clinical outcomes.

METHODS

A systematic review and meta-analysis were performed per PRISMA guidelines. We queried PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify articles reporting on patients who received RSA with LDT to restore ER and specified the site of tendon transfer insertion on the humerus. We first describe reported insertion sites in the literature. Secondarily, we present preoperative and postoperative range of motion and Constant score for different insertion sites as well as reported complications.

RESULTS

Sixteen studies, analyzed as 19 separate cohorts (by insertion site and tendon-transfer), reporting on 264 RSAs with LDT (weighted mean age 66 years, follow-up 39 months, 61% female) were evaluated. Of these, 143 (54%) included a concomitant teres major transfer (LDT/TMT) and 121 (46%) were LDT-only. Fourteen cohorts (14/19, 74%) reported insertion at the posterolateral aspect of the greater tuberosity, four cohorts (4/19, 21%) reported insertion site at the lateral bicipital groove, and one cohort (1/19, 5%) reported separate LDT and TMT with insertion of the TMT to the posterolateral aspect of the greater tuberosity and LDT to the lateral bicipital groove. Meta-analysis revealed no differences in range of motion or Constant score based on humeral insertion site or whether the LDT was transferred alone or with TMT. Leading complications included dislocation, followed by infection and neuropraxia. No discernible correlation was observed between postoperative outcomes and the strategies employed for tendon transfer, prosthesis design, or subscapularis management.

CONCLUSION

The posterolateral aspect of the greater tuberosity was the most-utilized insertion site for LDT performed with RSA. However, in the current clinical literature, LDT with or without concomitant TMT result in similar postoperative ROM and Constant score regardless of insertion site. Analysis of various proposed transfer sites reinforce the ability of LDT with RSA to restore both FE and ER in patients with preoperative active elevation and external rotation loss. Meta-analysis revealed significant improvements in range of motion and Constant score regardless of humeral insertion site or whether the LDT was transferred alone or with TMT, although future studies are needed to determine whether an ideal tendon transfer technique exists.

LEVEL OF EVIDENCE

IV.

Reverse shoulder arthroplasty design-inlay vs. onlay: does it really make a difference?

BACKGROUND

The design of reverse shoulder arthroplasty (RSA) implants has evolved significantly over the past 50 years. Today there are many options available that differ in design of the glenoid and humeral components, fixation methods, sizes, and modularity. With respect to the humeral component, the literature has generally focused on the differences between inlay and onlay designs and the potential impact on outcomes. However, inlay and onlay design represents only one factor of many.

METHODS

It is our hypothesis that separating onlay and inlay designs into 2 distinct entities is an oversimplification as there can be a wide overlap of the 2 designs, depending on surgical technique and the implant selected. As such, the differences between inlay and onlay designs should be measured in absolute terms-meaning combined distalization and lateralization.

RESULTS

By reviewing the many factors that can contribute to the glenosphere-humerus relationship, the role of inlay and onlay humeral designs as an important distinguishing feature is shown to be limited. Preliminary studies suggest that the amount of distalization and lateralization of the construct may be the most accurate method of describing the differences in the constructs.

CONCLUSIONS

Inlay and onlay humeral component design represents only one factor of many that may impact outcomes. A more accurate method of defining specific design and technique factors in RSA is the degree of lateralization and distalization.

Optimizing stability and motion in reverse shoulder arthroplasty with a 135° neck-shaft-angle: a computer model study of standard versus retentive humeral inserts

Background

There has been a trend to shift from a 155° and 145° neck-shaft-angle (NSA) to a more "anatomical" reverse shoulder arthroplasty with less distalization and a 135° NSA. Multiple studies have shown that a 135° NSA is beneficial for motion. There are some concerns about primary implant stability with a 135° NSA. When instability is detected, increasing the tension with thicker inlays or changing the NSA to 145° are possible solutions. A retentive 135° (Ret135) inlay may be an alternative to avoiding increased distalization; however, retentive liners are widely regarded as salvage options reducing range of motion (ROM) and avoided by most surgeons. The hypothesis of this study was that a retentive 135° insert of the tested implant system may not have drawbacks for impingement-free ROM compared to a standard 145° insert (Sta145).

Methods

In this computer model study, 22 computed tomographic scans (11 males/11 females) were used to create models with a constant humeral stem (Perform/Stryker) and +3 mm lateralized baseplate +36 mm glenosphere for females and +6 mm lateralized baseplate +39 mm glenosphere for males using Blueprint software (Imascap, Brest, France). A Ret135, standard 135° (Sta135), and Sta145 (+10°) insert were compared for adduction (ADD), extension (EXT), external rotation (ER), and internal rotation (IR) all with the arm at the side as well as for combined IR (CIR = EXT + IR) and combined notching relevant (CNR) ROM (EXT + ER + IR + ADD).

Results

Sta135 showed significantly better ROM for ER, IR, ADD, EXT, CNR ROM, and CIR compared to Ret135 (P < .05) and significantly better EXT and ADD compared to Sta145 (P < .0001). Comparison of Ret135 and Sta145 showed equivalent ROM performance, which was slightly better but nonsignificant for ADD (P = .16), EXT (P = .31), CNR ROM (P = .7), and CIR (P = .54) in favor of Ret135. Isolated IR (P = .39) and ER (P = .32) were slightly better but nonsignificant in favor of a Sta145.

Conclusion

For this implant system tested in a computer model, a 135° standard liner offers the best ROM. A 135° retentive liner maintains at least equivalent CIR and motion to prevent notching compared to a standard 145° liner. 135° retentive liners are more than salvage options and may help to prevent distalization and overtensioning by increased liner thickness.

Mitigating the Risk of Instability After Reverse Shoulder Arthroplasty: A Critical Analysis Review of Patient and Surgical Factors

» Instability and dislocation after reverse shoulder arthroplasty may occur in up to 31% of patients.

» Clinical risk factors for instability include younger age, male sex, increased body mass index, preoperative diagnosis of proximal humerus fracture or rotator cuff pathology, history of instability of the native shoulder or after surgery, and a medical history of Parkinson's disease.

» Patients with rheumatoid arthritis and decreased proximity to the coracoid may also be at greater risk.

» In patients at a high risk of instability, surgeons should consider a more lateralized prosthesis (particularly in patients with an incompetent rotator cuff), repairing the subscapularis (particularly when using a medialized prosthesis), and upsizing the glenosphere (>40 mm in male and 38-40 mm in female patients).

» While potentially useful, less evidence exists for the use of a constrained liner (particularly with a lateralized glenosphere and/or in low-demand patients) and rotating the polyethylene liner posteriorly to avoid impingement.

Greater distance from the glenosphere center to the acromion reduces risk of acromial impingement in semi-inlay reverse shoulder arthroplasty

Background

Recently, the issue of subacromial notching, caused by acromial impingement has been reported. The purpose of this study was to assess the impact of differences in the distance between the glenosphere center and the greater tuberosity (DGT) and the distance between the glenosphere center and the acromion (DA) on the closest distance between the greater tuberosity and the acromion during active abduction in shoulders with reverse total shoulder arthroplasty (RSA).

Methods

Eleven shoulders with semiinlay RSA were analyzed. Subjects underwent fluoroscopy during active scapular plane abduction. Computed tomography of their shoulders was performed to create three-dimensional (3D) implant models at a mean of 16 months after surgery. Using model-image registration techniques, poses of 3D implant models were iteratively adjusted to match their silhouettes with the silhouettes in the fluoroscopic images (shape matching), and 3D kinematics of implants were computed. The closest distance between the acromion and greater tuberosity was computed at maximum abduction. DA and DGT were measured from 3D surface models. Shoulders were divided into two groups based on DA and DGT measurements and their closest distance data were compared between the groups.

Results

There were 7 shoulders with DA ≥ DGT, and 4 shoulders with DA < DGT. Shoulders with DA ≥ DGT showed a significantly wider distance between the greater tuberosity and acromion at maximum abduction compared to those with DA < DGT (5.9 ± 2.4 mm vs. 0.6 ± 0.7 mm, respectively, P = .0021). There were no significant differences in maximum glenohumeral abduction angle and humeral abduction angle between the two groups. Although DA was significantly greater in shoulders with DA ≥ DGT than in those with DA < DGT (43.7 ± 4.4 mm vs. 35.1 ± 6.7 mm, respectively, P = .0275), there was no significant difference in DGT between the two groups.

Conclusion

When DGT is less than DA in shoulders with RSA, the closest distance between the greater tuberosity and the acromion at maximum abduction is significantly wider compared to cases where DGT is greater than DA by 3D measurement. Therefore, acromial impingement is less likely to occur in shoulders with RSA when DA is greater than DGT. To avoid acromial impingement, it might be important to make DA greater than DGT.

Influence of design features and brand of reverse shoulder arthroplasties on survivorship and reasons for revision surgery: results of 5,494 arthroplasties with up to 15 years' follow-up reported to the Norwegian Arthroplasty Register 2007-2022

BACKGROUND AND PURPOSE

We aimed to report the survival of different reverse shoulder arthroplasty (RSA) designs and brands, and factors associated with revision. The secondary aim was to evaluate the reasons for revision.

METHODS

We included 4,696 inlay and 798 onlay RSAs reported to the Norwegian Arthroplasty Register (NAR) 2007-2022. Kaplan-Meier estimates of survivorship and Cox models adjusted for age, sex, diagnosis, implant design, humeral fixation, and previous surgery were investigated to assess revision risks. The reasons for revision were compared using competing risk analysis.

RESULTS

Overall, the 10-year survival rate was 94% (confidence interval [CI] 93-95). At 5 years all brands exceeded 90%. Compared with Delta Xtend (n = 3,865), Aequalis Ascend Flex (HR 2.8, CI 1.7-4.6), Aequalis Reversed II (HR 2.2, CI 1.2-4.2), SMR (HR 2.5, CI 1.3-4.7), and Promos (HR 2.2, CI 1.0-4.9) had increased risk of revision. Onlay and inlay RSAs had similar risk of revision (HR 1.2, CI 0.8-1.8). Instability and deep infection were the most frequent revision causes. Male sex (HR 2.3, CI 1.7-3.1), fracture sequelae (HR 3.1, CI 2.1-5.0), and fractures operated on with uncemented humeral stems had increased risk of revision (HR 3.5, CI 1.6-7.3).

CONCLUSION

We found similar risk of revision with inlay and onlay designs. Some prosthesis brands had a higher rate of revision than the most common implant, but numbers were low.

Optimizing Muscle-Tendon Lengths in Reverse Total Shoulder Arthroplasty: Evaluation of Surgical and Implant-Design-Related Parameters

BACKGROUND

Optimizing the function of muscles that cross the glenohumeral articulation in reverse total shoulder arthroplasty (RTSA) is controversial. The current study used a geometric model of the shoulder to systematically examine surgical placement and implant-design parameters to determine which RTSA configuration most closely reproduces native muscle-tendon lengths of the deltoid and rotator cuff.

METHODS

A geometric model of the glenohumeral joint was developed and adjusted to represent small, medium, and large shoulders. Muscle-tendon lengths were assessed for the anterior deltoid, middle deltoid, posterior deltoid, and supraspinatus from 0 to 90° of scaption; for the subscapularis from 0° to 60° of internal rotation (IR) and 0° to 60° of scaption; for the infraspinatus from 0° to 60° of external rotation (ER) and 0° to 60° of scaption; and for the teres minor from 0° to 60° of ER at 90° of scaption. RTSA designs were virtually implanted using the following parameters: (1) surgical placement with a centered or inferior glenosphere position and a humeral offset of 0, 5, or 10 mm relative to the anatomic neck plane, (2) implant design involving a glenosphere size of 30, 36, or 42 mm, glenosphere lateralization of 0, 5, or 10 mm, and humeral neck-shaft angle of 135°, 145°, or 155°. Thus, 486 RTSA-shoulder size combinations were analyzed. Linear regression assessed the strength of association between parameters and the change in each muscle-tendon length from the native length.

RESULTS

The configuration that most closely restored anatomic muscle-tendon lengths in a small shoulder was a 30-mm glenosphere with a centered position, 5 mm of glenoid lateralization, 0 mm of humeral offset, and a 135° neck-shaft angle. For a medium shoulder, the corresponding combination was 36 mm, centered, 5 mm, 0 mm, and 135°. For a large shoulder, it was 30 mm, centered, 10 mm, 0 mm, and 135°. The most important implant-design parameter associated with restoration of native muscle-tendon lengths was the neck-shaft angle, with a 135° neck-shaft angle being favored (β = 0.568 to 0.657, p < 0.001). The most important surgical parameter associated with restoration of native muscle-tendon lengths was humeral offset, with a humeral socket placed at the anatomic neck plane being favored (β = 0.441 to 0.535, p < 0.001).

CONCLUSIONS

A combination of a smaller, lateralized glenosphere, a humeral socket placed at the anatomic neck plane, and an anatomic 135° neck-shaft angle best restored native deltoid and rotator cuff muscle-tendon lengths in RTSA.

CLINICAL RELEVANCE

This study of surgical and implant factors in RTSA highlighted optimal configurations for restoration of native muscle-tendon lengths of the deltoid and rotator cuff, which has direct implications for surgical technique and implant selection. Additionally, it demonstrated the most influential surgical and implant factors with respect to muscle-tendon lengths, which can be used to aid intraoperative decision-making.

Evolution of Reverse Shoulder Arthroplasty Design Rationales and Where We Are Now

Reverse shoulder arthroplasty (RSA) will soon reach its 20-year anniversary in the United States and has now become the most performed shoulder arthroplasty in the United States. The evolution from Grammont style implants to lateralized designs continues to generate debate as comparable outcomes have been reported with both types of systems. While early literature focused on fixation and expanded indications, recent studies have evaluated component design and position and their effect on functional outcomes and complications. The purpose of this article was to provide a synopsis of design rationales of current RSA prostheses and review outcomes related to RSA design and position.

Convertible-platform shoulder arthroplasty

Background

Shoulder arthroplasty has become an increasingly common procedure used to treat degenerative, inflammatory, and traumatic conditions of the glenohumeral joint. With a significant increase in primary anatomic and reverse total shoulder arthroplasty, revision procedures have likewise increased. Updates in shoulder arthroplasty have allowed for the convertibility of implants, which allows for the retention of both glenoid and humeral components during revision surgery. This review aims to highlight the epidemiology, indications, and outcomes of convertible-platform total shoulder arthroplasty procedures.

Methods

A review of the current literature surrounding convertible-platform shoulder arthroplasty was completed to highlight the advantages and disadvantages of commercially available instrumentation and implant systems as well as their outcomes.

Discussion

Leading causes of shoulder arthroplasty revision surgery include glenoid failure, implant instability, and rotator cuff dysfunction. Variations in implant design between inlay and onlay humeral components and metal-backed glenoid components are important considerations at the time of revision surgery. Advantages of convertible-platform systems include increased efficiency and decreased complications during revision procedures as well as shorter recovery, lower cost, and better functional outcomes. Limitations of convertible systems include poorly positioned components during the index procedure, excessive soft-tissue tensioning, and problems associated with metal-backed glenoid implants. Changes in arm length have also been documented. These findings indicate the benefit of additional research and design to improve the effectiveness and utility of convertible-platform shoulder arthroplasty systems.

Latissimus dorsi and teres major transfer in reverse shoulder arthroplasty: A systematic review

Background

This paper aims to conduct a systematic review of the current literature to evaluate the clinical outcomes of concurrent latissimus dorsi and teres major (LD/TM) tendon transfer in reverse shoulder arthroplasty (RSA), and to compare that to isolated RSA.

Methods

A comprehensive search on PubMeb, Web of Science, Embase and CINAHL was performed from inception up to January 20, 2023, in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses. Cohort studies, case-control studies, randomized controlled trials and case series that were written in English, which involved patients who underwent RSA with LD/TM transfer were included. Quality of studies was appraised using the Cochrane Risk Of Bias In Nonrandomized Studies of Interventions tool. Systematic review of Constant-Murley Score (CMS) and range of movement (ROM) was conducted.

Results

Eight studies with a total of 265 patients were included. The average mean follow-up time was 42.5 months, with a range of 6 months to 136 months. Of the studies that reported outcomes of RSA with LD/TM transfer, five reported the CMS, five reported external rotation (ER) ROM and six reported forward flexion ROM. Comparing postoperative to preoperative scores, there was an improvement above the minimal clinically important difference for CMS (mean difference (MD) range = 22.40 to 41.80), ER (MD range = 29° to 36°) and forward flexion (MD range = 50° to 75°). Three studies that compared postoperative ER between RSA with and without LD/TM reported no significant difference.

Conclusion

RSA with LD/TM transfer has good clinical outcomes postoperatively, but there is insufficient comparative data to suggest that it is superior or inferior to an isolated RSA.

Anatomic Versus Reverse Total Shoulder Arthroplasty for Primary Osteoarthritis With an Intact Rotator Cuff: A Midterm Comparison of Early Top Performers

BACKGROUND

Several surgeons state that their best anatomic total shoulder arthroplasty (aTSA) outperforms their best reverse total shoulder arthroplasty (rTSA) when performed for rotator cuff-intact glenohumeral osteoarthritis. We identified the top-performing aTSAs and rTSAs at short-term follow-up and compared their clinical performance at midterm follow-up to validate this common claim.

METHODS

A retrospective review of a multicenter shoulder arthroplasty database was conducted. All shoulders undergoing primary aTSA or rTSA for rotator cuff-intact glenohumeral osteoarthritis between 2007 and 2020 were reviewed. Shoulders with a follow-up clinical visit between 2 and 3 years and a clinical follow-up of minimum 5 years were included. Two separate cohorts were identified: patients with a top 20% (1) American Shoulder and Elbow Surgeons (ASES) score and (2) Shoulder Arthroplasty Smart (SAS) score at 2 to 3 years of follow-up. Clinical outcomes including range of motion, outcome scores, and rates of complications and revision surgeries were compared at minimum 5-year follow-up.

RESULTS

The ASES score cohort comprised 185 aTSAs (mean age 67 years, 42% female) and 49 rTSAs (mean age 72 years, 45% female). The SAS score cohort comprised 145 aTSAs (mean age 67 years, 59% female) and 42 rTSAs (mean age 71 years, 57% female). Active external rotation (ER) was greater after aTSA at midterm follow-up in both ASES and SAS score cohorts; however, preoperative to postoperative improvement was equivalent. Postoperative ER and SAS scores were greater after aTSA in both cohorts (P < 0.05); however, no other significant differences in any preoperative or postoperative clinical outcomes were present (P > 0.05), and patients achieved the minimal clinically important difference and substantial clinical benefit at similar rates for all outcomes. No difference was found in the incidence of complications and revision surgeries between top-performing aTSAs and rTSAs.

CONCLUSION

Among top-performing shoulder arthroplasties at early follow-up, aTSA does not appear to outperform rTSA, except superior ER at midterm follow-up.

LEVEL OF EVIDENCE

Retrospective comparative cohort study, Level Ⅲ.

Thresholds for diminishing returns in postoperative range of motion after total shoulder arthroplasty

BACKGROUND

Satisfaction following total shoulder arthroplasty (TSA), which is commonly reported using patient-reported outcome measures (PROMs), is partially dependent upon restoring shoulder range of motion (ROM). We hypothesized there exists a minimum amount of ROM necessary to perform functional tasks queried in PROM questionnaires, beyond which further ROM may provide no further improvement in PROMs.

METHODS

A retrospective review of a multicenter international shoulder arthroplasty database was performed between 2004 and 2020 for patients undergoing anatomic or reverse TSA (aTSA, rTSA), with minimum 2-year follow-up. Our primary outcome was to determine the threshold in postoperative active ROM (abduction, forward elevation [FE], external rotation [ER], and internal rotation [IR] score), whereby additional improvement was not associated with additional improvement in PROMs (Simple Shoulder Test, American Shoulder and Elbow Surgeons score, and the Shoulder Pain and Disability Index). For comparison, we also evaluated the Shoulder Arthroplasty Smart (SAS) score, which is not subject to the ceiling effect.

RESULTS

We included 4459 TSAs (1802 aTSAs, 2657 rTSAs) with minimum 2-year follow-up (mean, 56 ± 32 months). The threshold in postoperative ROM that were associated with no further improvement were active abduction, 107-113° for PROMs vs. 163° for the SAS score; active FE, 149-162° for PROMs vs. 176° for the SAS score; active ER, 50-52° for PROMs vs. 72° for the SAS score; IR score, 4-5 points for all PROMs vs. 6 points for the SAS score. Out of 3508 TSAs with complete postoperative ROM data, 8.5% achieved or exceeded all ROM thresholds (14.5% aTSAs, 4.8% rTSAs).

CONCLUSIONS

Our findings demonstrate that postoperative ROM exceeding 113° of abduction, 162° of FE, 52° of ER, and IR to L1 is associated with minimal additional improvement in PROMs. While individual patient needs vary, the thresholds may provide helpful targets for patients undergoing postoperative rehabilitation.

Glenoid lateralization in reverse shoulder arthroplasty: metal vs. bone offset in different implant designs

Background

Higher bone or metal glenoid offset in reverse shoulder arthroplasty (RSA) reduces scapular notching, improves range of motion (ROM), and reduces postoperative instability. This retrospective multicenter study compared two implant designs to evaluate the short-term clinical and radiologic results of bone increased offset RSA (BIO-RSA) and metal increased offset RSA (MIO-RSA) in reverse shoulder. We hypothesized no difference between groups.

Methods

This study analyzed n = 62 BIO-RSA and n = 90 MIO-RSA cases with a mean follow-up of 29.7 ± 6.0 months (BIO-RSA, range 24-49 months) and 24.0 ± 1.1 months (MIO-RSA, range 22-28 months). A 145°-onlay humeral stem was utilized in BIO-RSA cases, while a 135°-semi-inlay humeral stem was implanted in all MIO-RSA cases. Preoperative and postoperative radiologic imaging was reviewed to identify signs of scapular notching. Additionally, lateralization was evaluated according to Erickson et al. The constant score, subjective shoulder value, and ROM were evaluated during the baseline and follow-up consultations, and the findings of both groups were subsequently compared.

Results

Scapular notching was observed in 7.0% (n = 8) of MIO-RSA cases and 8.1% (n = 5) of BIO-RSA cases (P = .801). MIO-group had a higher lateralization angle (P = .020) and the BIO-group had a higher distalization angle (P = .005). At baseline, mean constant score in the MIO-RSA group was higher than in the BIO-RSA group (P < .001), and it significantly increased to 67.8 ± 12.1P (MIO-RSA) and 69.5 ± 12.3P (BIO-RSA) to a similar level (P = .399). ROM improved in both groups with no significant difference between the two groups at follow-up.

Conclusion

BIO-RSA and MIO-RSA in two distinct implant designs provide comparable short-term outcomes with a similar increase in shoulder function with notable variations in the lateralization and distalization angles between both implants. Scapular notching was rarely seen and unaffected by the method of glenoid lateralization. Follow-up investigations of both techniques are necessary to complement and track changes in the long-term outcome.

Clinical Outcomes Do Not Deteriorate Over Time Following Primary Reverse Total Shoulder Arthroplasty: Minimum 10-Year Follow-up of 135 Shoulders

Background

Reverse total shoulder arthroplasty (RTSA) offers satisfactory mid-term outcomes for a variety of pathologies, but long-term follow-up data are limited. This study demonstrates the long-term clinical and radiographic outcomes as well as the predictive factors for an inferior outcome following RTSA.

Methods

Using the prospective database of a single, tertiary referral center, we included all primary RTSAs that were performed during the study period and had a minimum 10-year follow-up. Clinical outcomes included the absolute Constant-Murley score (CS), relative CS, Subjective Shoulder Value (SSV), range of motion, pain, complication rate, and reintervention rate. Radiographic measurements included the critical shoulder angle (CSA), lateralization shoulder angle (LSA), distalization shoulder angle (DSA), reverse shoulder angle (RSA), acromiohumeral distance (ACHD), center of rotation, glenoid component height, notching, radiolucent lines, heterotopic ossification, and tuberosity resorption.

Results

A total of 135 shoulders (133 patients) were available for analysis at a mean follow-up of 10.9 ± 1.6 years. The mean age was 69 ± 8 years, and 76 shoulders (76 patients; 56%) were female. For most of the clinical outcomes, initial improvements were observed in the short term and were sustained in the long term without notable deterioration, with >10-year follow-up values of 64 ± 16 for the absolute CS, 79% ± 18% for the relative CS, 79% ± 21% for the SSV, and 14 ± 3 for the CS for pain. However, after initial improvement, deterioration was seen for flexion and external rotation, with values of 117° ± 26° and 25° ± 18°, respectively, at the final follow-up. Scapular notching, heterotopic ossification, and radiolucent lines of <2 mm progressed during the study period. Younger age (p = 0.040), grade-II notching (p = 0.048), tuberosity resorption (p = 0.015), and radiolucent lines of <2 mm around the glenoid (p = 0.015) were predictive of an inferior outcome. The complication rate was 28%, with a reintervention rate of 11%.

Conclusions

RTSA provided improved long-term results that did not significantly deteriorate over time for most of the clinical parameters. Negative clinical outcome predictors were younger age, grade-II notching, tuberosity resorption, and radiolucent lines of <2 mm around the glenoid.

Level of Evidence

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Bone Density Changes at the Origin of the Deltoid Muscle following Reverse Shoulder Arthroplasty

Background: Reverse total shoulder arthroplasty (RSA) significantly impacts deltoid length, tension, and structure. Studies have extensively investigated various modifications in deltoid characteristics, such as perfusion, elasticity, caliber, histological changes, and strength post-RSA. However, to date, there is a notable absence of research evaluating changes in bone mineral density (BMD) at the deltoid muscle origin after the RSA procedure. Methods: A retrospective analysis of a consecutive series of RSAs performed between May 2011 and May 2022 was conducted. Inclusion criteria comprised primary RSAs with both preoperative and last follow-up shoulder CT scans and a minimum follow-up of 12 months. Trabecular attenuation measured in Hounsfield units (HU) was calculated using a rapid region-of-interest (ROI) method. BMD analysis involved segmenting three ROIs in both pre- and postoperative CT scans of each patient: the acromion, clavicle, and spine of the scapula. Results: A total of 44 RSAs in 43 patients, comprising 29 women and 14 men, were included in this study. The mean follow-up duration was 49 ± 22.64 months. Significant differences were observed between preoperative and postoperative HU values in all analyzed regions. Specifically, BMD increased in the acromion and spine, while it decreased in the clavicle (p-values 0.0019, <0.0001, and 0.0088, respectively). Conclusions: The modifications in shoulder biomechanics and, consequently, deltoid tension post-implantation result in discernible variations in bone quality within the analyzed regions. This study underscores the importance of thorough preoperative patient planning. By utilizing CT images routinely obtained before reverse shoulder replacement surgery, patients at high risk for fractures of the acromion, clavicle, and scapular spine can be identified.

Tendon transfers in reverse total shoulder arthroplasty: A systematic review and descriptive synthesis of biomechanical studies

BACKGROUND

The role of tendon transfer and ideal insertion sites to improve axial rotation in reverse total shoulder arthroplasty (RTSA) is debated. We systematically reviewed the available biomechanical evidence to elucidate the ideal tendon transfer and insertion sites for restoration of external and internal rotation in the setting of RTSA and the influence of implant lateralization.

PATIENTS AND METHODS

We queried the PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify biomechanical studies examining the application of tendon transfer to augment shoulder external or internal rotation range of motion in the setting of concomitant RTSA. A descriptive synthesis of six included articles was conducted to elucidate trends in the literature.

RESULTS

Biomechanics literature demonstrates that increasing humeral-sided lateralization optimized tendon transfers performed for both ER and IR. The optimal latissimus dorsi (LD) transfer site for ER is posterior to the greater tuberosity (adjacent to the teres minor insertion); however, LD transfer to this site results in greater tendon excursion compared to posterodistal insertion site. In a small series with nearly 7-year mean follow-up, the LD transfer demonstrated longevity with all 10 shoulders having>50% ER strength compared to the contralateral native shoulder and a negative Hornblower's at latest follow-up; however, reduced electromyography activity of the transferred LD compared to the native contralateral side was noted. One study found that transfer of the pectoralis major has the greatest potential to restore IR in the setting of lateralized humerus RTSA.

CONCLUSION

To restore ER, LD transfer posterior on the greater tuberosity provides optimal biomechanics with functional longevity. The pectoralis major has the greatest potential to restore IR. Future clinical investigation applying the biomechanical principles summarized herein is needed to substantiate the role of tendon transfer in the modern era of lateralized RTSA.

LEVEL OF EVIDENCE

IV; systematic review.

Can we separately measure glenoid vs. humeral lateralization and distalization in reverse shoulder arthroplasty?

BACKGROUND

Lateralization and distalization in reverse shoulder arthroplasty (RSA) can be measured on anteroposterior (AP) radiographs using 2 previously described angles: lateralization shoulder angle (LSA) and distalization shoulder angle (DSA). However, these 2 angles measure global lateralization and distalization but do not allow to differentiate how much lateralization or distalization are attributable to the glenoid and the humerus. We hypothesized that new angles could allow us to separately measure glenoid vs. humeral lateralization and distalization. A more precise understanding of independent glenoid and humeral contributions to lateralization and distalization may be beneficial in subsequent clinical research.

METHOD

Retrospective analysis of postoperative AP radiographs of 100 patients who underwent primary RSA for cuff-tear arthropathy, massive cuff tear, or glenohumeral osteoarthritis were analyzed. The new angles that we proposed use well-known bony landmarks (the acromion, glenoid, and humerus) and the most lateral point of the glenosphere, which we termed the "glenoid pivot point" (GPP). For lateralization, we used the GPP to split LSA into 2 new angles: glenoid lateralization angle (GLA) and humeral lateralization angle (HLA). For distalization, we introduced the modified distalization shoulder angle (mDSA) that can also be split into 2 new angles: glenoid distalization angle (GDA) and humeral distalization angle (HDA). Three orthopedic surgeons measured the new angles, using the online tool Tyche. Mean values with overall and individual standard deviations as well as intraclass correlation coefficients (ICCs) were calculated.

RESULTS

Because the angles form a triangle, the following equations can be made: LSA = GLA + HLA, and mDSA = GDA + HDA. All angles showed excellent inter- and intraobserver reliability (ICC = 0.92-0.97) with low means of individual standard deviations that indicate a precision of 2° for each angle.

CONCLUSION

Use of the most lateral part of the glenosphere (termed glenoid pivot point) allows us to separately measure glenoid vs. humeral lateralization and distalization. The 4 new angles (HLA, GLA, GDA, HDA) described in the present study can be used on true AP radiographs, routinely obtained after shoulder replacement, and the measured angles may be used with all types of reverse prostheses available.

Pectoralis major tendon transfer in reverse total shoulder arthroplasty with irreparable subscapularis: surgical technique and preliminary clinical and radiological results

Hypothesis/Background

Addressing irreparable subscapularis in conjunction with reverse total shoulder arthroplasty (RTSA) presents challenges. RTSA without subscapularis repair leads to similar clinical results compared to those with a subscapularis repair but with less range of motion in internal rotation (IR). Optimization of IR and anterior stability after RTSA, in the setting of an irreparable subscapularis may be achieved with a pectoralis major (PM) tendon transfer. This study aims to describe a novel surgical technique involving PM transfer in RTSA for irreparable subscapularis and report the initial clinical and radiological outcomes.

Methods

This study included 13 patients with an average of 65.5 years (range, 52-82 years). All patients underwent a lateralized RTSA with concurrent PM transfer, associated to an irreparable subscapularis, performed by a single surgeon (PV). Preoperative and postoperative range of motion, including internal rotation 1, internal rotation 2, external rotation 1 (ER1) and forward elevation, were measured. The absolute Constant score, the age and sex-adjusted Constant Murley score, Visual Analog Scale and subjective shoulder value were evaluated by the same surgeon. Standard X-rays, preoperative magnetic resonance imaging, and computed tomography scan were performed for all patients.

Results

With an average follow-up of 37 months, the mean Constant score improved from 17.7 preoperatively to 61 postoperative (P < .05). Postoperative clinical outcomes significantly improved across the study group. Mean internal rotation 2 increased from 44.6° to 61.5° (P < .05), while internal rotation 1 improved from 2.6 to 5 (P < .05). The Gerber test yielded positive results for all patients, while the belly press test was negative for eleven patients. Postoperative imaging assessment of the transferred PM tendon transfer showed intact repair, a good cicatrization on the lesser tuberosity with excellent trophicity of the muscle without any fatty infiltration in all patients.

Conclusion

PM transfer combined with a lateralized RSTA in cases of irreparable subscapularis leads to improved shoulder range of motion, particularly in IR, increased strength and pain relief.

[Reverse Shoulder Arthroplasty - Current Concepts]

Due to first promising long term outcome data, reverse shoulder arthroplasty experienced an immense increase of usage during the past decade. Moreover, the initial Grammont concept has constantly been refined and adapted to current scientific findings. Therefore, clinical and radiological problems like scapular notching and postoperative instability were constantly addressed but do still remain an area of concern.This article summarises current concepts in reverse shoulder arthroplasty and gives an overview of actual indications like cuff tear arthropathy, severe osteoarthritis, proximal humerus fractures, tumours, fracture sequelae as well as revision surgery and their corresponding clinical and radiological results.

Clinical outcomes of anatomic vs. reverse total shoulder arthroplasty in primary osteoarthritis with preoperative external rotation weakness and an intact rotator cuff: a case-control study

BACKGROUND

Anatomic (aTSA) and reverse total shoulder arthroplasty (rTSA) are well-established treatments for patients with primary osteoarthritis and an intact cuff. However, it is unclear whether aTSA or rTSA provides superior outcomes in patients with preoperative external rotation (ER) weakness.

METHODS

A retrospective review of a prospectively collected shoulder arthroplasty database was performed between 2007 and 2020. Patients were excluded for preoperative diagnoses of nerve injury, infection, tumor, or fracture. The analysis included 333 aTSAs and 155 rTSAs performed for primary cuff-intact osteoarthritis with 2-year minimum follow-up. Defining preoperative ER weakness as strength <3.3 kilograms (7.2 pounds), 3 cohorts were created and matched: (1) weak aTSAs (n = 74) vs. normal aTSAs (n = 74), (2) weak rTSAs (n = 38) vs. normal rTSAs (n = 38), and (3) weak rTSAs (n = 60) vs. weak aTSAs (n = 60). We compared range of motion, outcome scores, strength, complications, and revision rates at the latest follow-up.

RESULTS

Despite weak aTSAs having poorer preoperative strength in forward elevation and ER (P < .001), neither of these deficits persisted postoperatively compared with the normal cohort. Likewise, weak rTSAs had poorer preoperative strength in forward elevation and ER, overhead motion, and Constant, Shoulder Pain and Disability Index, and University of California, Los Angeles scores (P < .029). However, no statistically significant differences were found between preoperatively weak and normal rTSAs. When comparing weak aTSA vs. weak rTSA, no differences were found in preoperative and postoperative outcomes, proportion of patients achieving the minimal clinically important difference and substantial clinical benefit, and complication and rate of revision surgery.

CONCLUSIONS

In preoperatively weak patients with cuff-intact primary osteoarthritis, aTSA leads to similar postoperative strength, range of motion, and outcome scores compared with patients with normal preoperative strength, indicating that preoperative weakness does not preclude aTSA use. Furthermore, patients who were preoperatively weak in ER demonstrated improved postoperative rotational motion after undergoing aTSA and rTSA, with both groups achieving the minimal clinically important difference and substantial clinical benefit at similar rates.

Analysis of three different reverse shoulder arthroplasty designs for cuff tear arthropathy - the combination of lateralization and distalization provides best mobility

BACKGROUND

The two major reverse shoulder arthroplasty (RSA) designs are the Grammont design and the lateralized design. Even if the lateralized design is biomechanically favored, the classic Grammont prosthesis continues to be used. Functional and subjective patient scores as well as implant survival described in the literature so far are comparable to the lateralized design. A pure comparison of how the RSA design influences outcome in patients has not yet been determined. The aim of this study was a comparison focused on patients with cuff tear arthropathy (CTA).

METHODS

We analyzed registry data from 696 CTA patients prospectively collected between 2012 and 2020 in two specialized orthopedic centers up to 2 years post-RSA with the same follow-up time points (6,12 24 months). Complete teres minor tears were excluded. Three groups were defined: group 1 (inlay, 155° humeral inclination, 36 + 2 mm eccentric glenosphere (n = 50)), group 2 (inlay, 135° humeral inclination, 36 + 4 mm lateralized glenosphere (n = 141)) and group 3 (onlay, 145° humeral inclination, + 3 mm lateralized base plate, 36 + 2 mm eccentric glenosphere (n = 35)) We compared group differences in clinical outcomes (e.g., active and passive range of motion (ROM), abduction strength, Constant-Murley score (CS)), radiographic evaluations of prosthetic position, scapular anatomy and complications using mixed models adjusted for age and sex.

RESULTS

The final analysis included 226 patients. The overall adjusted p-value of the CS for all time-points showed no significant difference (p = 0.466). Flexion of group 3 (mean, 155° (SD 13)) was higher than flexion of group 1 (mean, 142° (SD 18) and 2 (mean, 132° (SD 18) (p < 0.001). Values for abduction of group 3 (mean, 145° (SD 23)) were bigger than those of group 1 (mean, 130° (SD 22)) and group 2 (mean, 118° (SD 25)) (p < 0.001). Mean external rotation for group 3 (mean, 41° (SD 23)) and group 2 (mean, 38° (SD 17)) was larger than external rotation of group 1 (mean, 24° (SD 16)) (p < 0.001); a greater proportion of group 2 (78%) and 3 (69%) patients reached L3 level on internal rotation compared to group 1 (44%) (p = 0.003). Prosthesis position measurements were similar, but group 3 had significantly less scapular notching (14%) versus 24% (group 2) and 50% (group 1) (p = 0.001).

CONCLUSIONS

Outcome scores of different RSA designs for CTA revealed comparable results. However, CTA patients with a lateralized and distalized RSA configuration were associated with achieving better flexion and abduction with less scapular notching. A better rotation was associated with either of the lateralized RSA designs in comparison with the classic Grammont prosthesis.

LEVEL OF EVIDENCE

Therapeutic study, Level III.

Humeral head size predicts baseplate lateralization in reverse shoulder arthroplasty: a comparative computer model study

Background

In reverse shoulder arthroplasty (RSA), the ideal combination of baseplate lateralization (BL), glenosphere size (GS), and glenosphere overhang (GOH) with a commonly used 145° neck shaft angle (NSA) is unclear. This is the first study evaluating correlations of body height (BH), humeral head size (HS), glenoid height (GH), and association of gender with best glenoid configurations for range of motion (ROM) maintaining anatomic lateralization (aLAT) for optimized muscle length in 145° and less distalized 135° RSA.

Methods

In this computer model study, 22 computed tomographies without joint narrowing were analyzed (11 male/female). A standardized semi-inlay 145° platform stem was combined with 20 glenoid configurations (baseplate [B] 25, 25 + 3/+6 lateralized [l], 29, 29 + 3/6l combined with glenosphere 36, 36 + 2 eccentric [e], 36 + 3l, 39, 39 + 3e, 39 + 3l , 42, 42 + 4e). Abduction-adduction, flexion-extension, external rotation-internal rotation, total ROM (TROM), and total notching relevant (TNR) ROM were computed, best TROM models respecting aLAT (-1 mm to +1 mm) and HS/GH recorded. Second, the 145° models (Ascend Flex stem; Stryker, Kalamazoo, MI, USA) were converted and compared to a 135° inlay RSA (New Perform stem; Stryker, Kalamazoo, MI, USA) maintaining GOH (6.5-7 mm) and aLAT.

Results

Best 145° models had eccentric glenospheres (mean BL: 3.5 mm, GOH 8.8 mm, GS 38.1 mm, distalization 23 mm). The 135° models had concentric glenospheres, mean BL 3.8 mm, GOH 6.9 mm, GS 39.7 mm, and distalization 14.1 mm. HS showed the strongest positive correlation with BL in 145° and 135° models (0.65/0.79). Despite reduced GOH in smaller females with a 135° NSA, adduction, external rotation, extension, TNR ROM, and TROM were significantly increased (P = .02, P = .005, P = .005, P = .004, P = .003), abduction however reduced (P = .02). The same trends were seen for males.

Conclusion

HS is a practical measure in surgery or preoperatively, and the strong positive correlation with BL is a useful planning aid. Despite reduction of GOH, conversion to a less distalized 135° NSAinlay design is powerful to maintain and even significantly increase all components of TNR ROM (extension/external rotation/adduction) in small females with the drawback of reduced abduction which may however be compensated by scapula motion. Lateralization with a less distalized 135° RSA optimizes muscle length, may facilitate subscapularis repair, and maintains highest rigid body motion.

Influence of lateralized versus medialized reverse shoulder arthroplasty design on external and internal rotation: a systematic review and meta-analysis

BACKGROUND

Restoration of external (ER) and internal rotation (IR) after Grammont-style reverse shoulder arthroplasty (RSA) is often unreliable. The purpose of this systematic review was to evaluate the influence of RSA medio-lateral offset and subscapularis repair on axial rotation after RSA.

METHODS

We conducted a systematic review of studies evaluating axial rotation (ER, IR, or both) after RSA with a defined implant design. Medio-lateral implant classification was adopted from Werthel et al. Meta-analysis was conducted using a random-effects model.

RESULTS

Thirty-two studies reporting 2,233 RSAs were included (mean patient age, 72.5 years; follow-up, 43 months; 64% female). The subscapularis was repaired in 91% (n=2,032) of shoulders and did not differ based on global implant lateralization (91% for both, P=0.602). On meta-analysis, globally lateralized implants achieved greater postoperative ER (40° [36°-44°] vs. 27° [22°-32°], P<0.001) and postoperative improvement in ER (20° [15°-26°] vs. 10° [5°-15°], P<0.001). Lateralized implants with subscapularis repair or medialized implants without subscapularis repair had significantly greater postoperative ER and postoperative improvement in ER compared to globally medialized implants with subscapularis repair (P<0.001 for both). Mean postoperative IR was reported in 56% (n=18) of studies and achieved the minimum necessary IR in 51% of lateralized (n=325, 5 cohorts) versus 36% (n=177, 5 cohorts) of medialized implants.

CONCLUSIONS

Lateralized RSA produces superior axial rotation compared to medialized RSA. Lateralized RSA with subscapularis repair and medialized RSA without subscapularis repair provide greater axial rotation compared to medialized RSA with subscapularis repair. Level of evidence: 2A.

Stemless Reverse Shoulder Arthroplasty

Since the Food and Drug Administration (FDA) approval nearly two decades ago, the indications for and utilization of reverse shoulder arthroplasty (RSA) have expanded considerably. Stemless RSA designs have been used in Europe since 2005, but have only recently been introduced in domestic Investigational Device Exemption trials. Potential advantages of stemless RSA are similar to those of stemless anatomic total shoulder arthroplasty, which may include fewer shaft-related complications, avoidance of stress shielding, bone preservation, and easier revision surgery. European data support similar outcomes between certain stemless RSA prostheses compared with that of stemmed RSA implants at early and mid-term follow-up. However, long-term outcomes remain to be seen and differences exist between the stemless RSA designs used in Europe and those being studied in domestic clinical trials. An understanding of the potential advantages and disadvantages of stemless RSA, differences between existing designs, and reported clinical outcomes is prudent for the safe and meaningful implementation of this new technology in the United States.

Influence of Lateralization and Distalization on Joint Function after Primary Reverse Total Shoulder Arthroplasty

The purpose of this study was to investigate how lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) are related to clinical and kinematic outcomes after reverse total shoulder arthroplasty. Thirty-three patients were evaluated at least six months postoperatively. The Single Assessment Numeric Evaluation (SANE), Constant Murley Score (CMS), Simple Shoulder Test (SST), and Visual Analogue Scale (VAS) were used. Shoulder kinematics was evaluated with a stereophotogrammetric system. LSA and DSA inter-rater reliability was analysed through the interclass correlation coefficient (ICC). Stepwise forward linear regression analysis was conducted between LSA and DSA with clinical scales and kinematic measures, between which a correlation analysis was conducted. The inter-rater reliability for LSA (mean ICC = 0.93) and DSA (mean ICC = 0.97) results were good to excellent. Greater LSA values were associated with higher peaks of internal rotation (p = 0.012, R2 = 0.188) and range of motion (ROM) (p = 0.037, R2 = 0.133). SANE (p = 0.009), CMS (p = 0.031), and SST (0.026) were positively correlated to external rotation, while VAS (p = 0.020) was negatively related. Abduction peaks were positively related to CMS (p = 0.011) and SANE (p = 0.037), as well as abduction ROM (SANE, p = 0.031; CMS, p = 0.014).

Clinical outcomes of anatomical versus reverse total shoulder arthroplasty in patients with primary osteoarthritis, an intact rotator cuff, and limited forward elevation

Aims

Both anatomical and reverse total shoulder arthroplasty (aTSA and rTSA) provide functional improvements. A reported benefit of aTSA is better range of motion (ROM). However, it is not clear which procedure provides better outcomes in patients with limited foward elevation (FE). The aim of this study was to compare the outcome of aTSA and rTSA in patients with glenohumeral osteoarthritis (OA), an intact rotator cuff, and limited FE.

Methods

This was a retrospective review of a single institution's prospectively collected shoulder arthroplasty database for TSAs undertaken between 2007 and 2020. A total of 344 aTSAs and 163 rTSAs, which were performed in patients with OA and an intact rotator cuff with a minimum follow-up of two years, were included. Using the definition of preoperative stiffness as passive FE ≤ 105°, three cohorts were matched 1:1 by age, sex, and follow-up: stiff aTSAs (85) to non-stiff aTSAs (85); stiff rTSAs (74) to non-stiff rTSAs (74); and stiff rTSAs (64) to stiff aTSAs (64). We the compared ROMs, outcome scores, and complication and revision rates.

Results

Compared with non-stiff aTSAs, stiff aTSAs had poorer passive FE and active external rotation (ER), whereas there were no significant postoperative differences between stiff rTSAs and non-stiff rTSAs. There were no significant differences in preoperative function when comparing stiff aTSAs with stiff rTSAs. However, stiff rTSAs had significantly greater postoperative active and passive FE (p = 0.001 and 0.004, respectively), and active abduction (p = 0.001) compared with stiff aTSAs. The outcome scores were significantly more favourable in stiff rTSAs for the Shoulder Pain and Disability Index, Simple Shoulder Test, American Shoulder and Elbow Surgeons score, University of California, Los Angeles score, and the Constant score, compared with stiff aTSAs. When comparing the proportion of stiff aTSAs versus stiff rTSAs that exceeded the minimal clinically important difference and substantial clinical benefit, stiff rTSAs achieved both at greater rates for all measurements except active ER. The complication rate did not significantly differ between stiff aTSAs and stiff rTSAs, but there was a significantly higher rate of revision surgery in stiff aTSAs (p = 0.007).

Conclusion

Postoperative overhead ROM, outcome scores, and rates of revision surgery favour the use of a rTSA rather than aTSA in patients with glenohumeral OA, an intact rotator cuff and limited FE, with similar rotational ROM in these two groups.

Impact of reverse shoulder arthroplasty design and patient shoulder size on moment arms and muscle fiber lengths in shoulder abductors

BACKGROUND

Reverse shoulder arthroplasty (RSA) increases the moment arm of the deltoid; however, there is limited knowledge on the accompanying changes in muscle architecture that play a role in muscle force production. The purpose of this study was to use a geometric shoulder model to evaluate the anterior deltoid, middle deltoid, and supraspinatus regarding (1) the differences in moment arms and muscle-tendon lengths in small, medium, and large native shoulders and (2) the impact of 3 RSA designs on moment arms, muscle fiber lengths, and force-length (F-L) curves.

METHODS

A geometric model of the native glenohumeral joint was developed, validated, and adjusted to represent small, medium, and large shoulders. Moment arms, muscle-tendon lengths, and normalized muscle fiber lengths were assessed for the supraspinatus, anterior deltoid, and middle deltoid from 0° to 90° of abduction. RSA designs were modeled and virtually implanted, including a lateralized glenosphere with an inlay 135° humeral component (lateral glenoid-medial humerus [LGMH]), a medialized glenosphere with an onlay 145° humeral component (medial glenoid-lateral humerus [MGLH]), and a medialized glenosphere with an inlay 155° humeral component (medial glenoid-medial humerus [MGMH]). Descriptive statistics were used to compare moment arms and normalized muscle fiber lengths.

RESULTS

As shoulder size increased, the moment arms and muscle-tendon lengths for the anterior deltoid, middle deltoid, and supraspinatus increased. All RSA designs achieved greater moment arms for the anterior and middle deltoid, with the MGLH design achieving the largest increase. The resting normalized muscle fiber length of the anterior and middle deltoid was substantially increased in the MGLH (1.29) and MGMH (1.24) designs, shifting the operating ranges of these muscles to the descending portions of their F-L curves, whereas the LGMH design maintained a resting deltoid fiber length (1.14) and operating range similar to the native shoulder. All RSA designs demonstrated a decrease in the native supraspinatus moment arm in early abduction, with the largest decrease in the MGLH design (-59%) and minimal decrease in the LGMH design (-14%). The supraspinatus operated on the ascending limb of its F-L curve in the native shoulder and remained on this portion of the F-L curve for all RSA designs.

CONCLUSION

Although the MGLH design maximizes the abduction moment arm for the anterior and middle deltoid, overlengthening of the muscle may compromise deltoid muscle force production by forcing the muscle to operate on the descending portion of its F-L curve. In contrast, the LGMH design increases the abduction moment arm for the anterior and middle deltoid more modestly while allowing the muscle to operate near the plateau of its F-L curve and maximizing its force-producing potential.

Associations between radiographic parameters in the reverse shoulder arthroplasty and patient outcomes

Background

Various radiological parameters have been measured in the Reverse Shoulder Arthroplasty (RSA) and correlated to patient outcomes, to determine best baseplate position. Results remain unclear with respect to certain parameters such as inferior baseplate tilt. We have investigated our series of patients to clarify the relationship between radiological parameters and patient outcomes.

Methods

We conducted a UK based bi-centre retrospective review of 156 prostheses. Critical shoulder angle (CSA), RSA angle (RSAA), Overhang and Deltoid Lever Arm (DLA) were measured on preoperative and postoperative radiographs. Range of motion and Oxford Shoulder Score (OSS) (range 1-8 years) were obtained. We assessed for scapular notching at minimum 1 year follow up (n = 138).

Results

Decreased postoperative CSA and increased DLA were associated with higher OSSs (P = 0.001 and 0.019). Increased overhang and DLA were associated with increased flexion (P = 0.033 and 0.024 respectively). Multivariate analysis showed that CSA and DLA affected notching rate (P = 0.002 and 0.007).

Conclusions

Baseplate tilt in relation to the acromion (CSA) and DLA are the most predictive parameters for notching and OSS. We recommend considering a maximum CSA of 26 degrees to decrease notching rate and improve OSS. We recommend considering an Overhang of at least 6 mm to improve FF.

Discordance between patient-reported and objectively measured internal rotation after reverse shoulder arthroplasty

BACKGROUND

Patient satisfaction after reverse shoulder arthroplasty (RSA) partly relies on restoring functional internal rotation (IR). Although postoperative assessment of IR includes objective appraisal by the surgeon and subjective report from the patient, these evaluations may not vary together uniformly. We assessed the relationship between objective, surgeon-reported assessments of IR and subjective, patient-reported ability to perform IR-related activities of daily living (IRADLs).

METHODS

Our institutional shoulder arthroplasty database was queried for patients undergoing primary RSA with a medialized-glenoid lateralized-humerus design between 2007-2019 and minimum 2-year follow-up. Patients who were wheelchair bound or had a preoperative diagnosis of infection, fracture, and tumor were excluded. Objective IR was measured to the highest vertebral level reached with the thumb. Subjective IR was reported based on patients' rating (normal, slightly difficult, very difficult, or unable) of their ability to perform 4 IRADLs (tuck in shirt with hand behind back, wash back or fasten bra, personal hygiene, and remove object from back pocket). Objective IR was assessed preoperatively and at latest follow-up and reported as median and interquartile ranges.

RESULTS

A total of 443 patients were included (52% female) at a mean follow-up of 4.4 ± 2.3 years. Objective IR improved pre- to postoperatively from L4-L5 (buttocks to L1-L3) to L1-L3 (L4-L5 to T8-T12) (P < .001). Preoperatively reported IRADLs of "very difficult" or "unable" significantly decreased postoperatively for all IRADLs (P ≤ .004) except those unable to perform personal hygiene (3.2% vs. 1.8%, P > .99). The proportions of patients who improved, maintained, and lost objective and subjective IR was similar between IRADLs; 14%-20% improved objective IR but lost or maintained subjective IR and 19%-21% lost or maintained the same objective IR but improved subjective IR depending on the specific IRADL assessed. When ability to perform IRADLs improved postoperatively, objective IR also increased (P < .001). In contrast, when subjective IRADLs worsened postoperatively, objective IR did not significantly worsen for 2 of 4 IRADLs assessed. When examining patients who reported no change in ability to perform IRADLs pre- vs. postoperatively, statistically significant increases in objective IR were found for 3 of 4 IRADLs assessed.

CONCLUSIONS

Objective improvement in IR parallels improvements in subjective functional gains uniformly. However, in patients with worse or equivalent IR, the ability to perform IRADLs postoperatively does not uniformly correlate with objective IR. When attempting to elucidate how surgeons can ensure patients will have sufficient IR after RSA, future investigations may need to use patient-reported ability to perform IRADLs as the primary outcome measure rather than objective measures of IR.

The association between humeral lengthening and clinical outcomes after reverse shoulder arthroplasty: a systematic review and meta-analysis

BACKGROUND

The purpose of this study was to evaluate the relationship between humeral lengthening and clinical outcomes after reverse shoulder arthroplasty (RSA) with stratification based on measurement method and implant design.

METHODS

This systematic review was performed using PRISMA-P guidelines. PubMed/Medline, Cochrane Trials, and Embase were queried for articles evaluating the relationship between humeral lengthening and clinical outcomes inclusive of range of motion (ROM), strength, outcome scores, and pertinent complications (acromial and scapular spine fractures, nerve injury) after RSA. The relationship between humeral lengthening and clinical outcomes was reported descriptively overall and stratified by measurement method and implant design (globally medialized vs. lateralized). A positive association was defined as increased humeral lengthening being associated with greater ROM, outcome scores, or a greater incidence of complications, whereas a negative association denoted that increased humeral lengthening was associated with poorer ROM, outcome scores, or a lower incidence of complications. Meta-analysis was performed to compare humeral lengthening between patients with and without fractures of the acromion or scapular spine.

RESULTS

Twenty-two studies were included. Humeral lengthening was assessed as the acromiohumeral distance (AHD), the distance from the acromion to the greater tuberosity (AGT), the acromion to the deltoid tuberosity (ADT), and the acromion to the distal humerus (ADH). Of 11 studies that assessed forward elevation, a positive association with humeral lengthening was found in 6, a negative association was found in 1, and 4 studies reported no association. Of studies assessing internal rotation (n = 9), external rotation (n = 7), and abduction (n = 4), all either identified a positive or lack of association with humeral lengthening. Studies assessing outcome scores (n = 11) found either a positive (n = 5) or no (n = 6) association with humeral lengthening. Of the studies that assessed fractures of the acromion and/or scapular spine (n = 6), 2 identified a positive association with humeral lengthening, 1 identified a negative association, and 3 identified no association. The single study that assessed the incidence of nerve injury identified a positive association with humeral lengthening. Meta-analysis was possible for AGT (n = 2) and AHD (n = 2); greater humeral lengthening was found in patients with fractures for studies using the AGT (mean difference 4.5 mm, 95% CI 0.7-8.3) but not the AHD. Limited study inclusion and heterogeneity prohibited identification of trends based on method of measuring humeral lengthening and implant design.

CONCLUSION

The relationship between humeral lengthening and clinical outcomes after RSA remains unclear and requires future investigation using a standardized assessment method.

Multiplanar analysis of proximal humerus anatomy of patients with rotator cuff arthropathy and relevance to reverse shoulder press-fit stems

Background

Short stems have become increasingly popular in reverse shoulder arthroplasty (RSA) due to their ability to preserve bone stock for revision surgery. However, short stems may be more at risk for malalignment or loosening, and commercially available stems have varied designs. The purpose of this study was to perform a multiplanar analysis of proximal humerus anatomy in patients with rotator cuff arthropathy to better define canal geometry and identify differences based on sex.

Methods

A retrospective review was performed of a consecutive series of patients undergoing RSA for rotator cuff arthropathy. A total of 117 patients were identified with preoperative computed tomography scans. Measurements were undertaken following multiplanar reconstruction of the computed tomography scans. Measured parameters included the following: transition point (TP), anteroposterior (AP) and mediolateral (ML) distances, intramedullary (IM) and bone diameter, and cortical thickness. The TP was defined as the distance from the periosteal border of the greater tuberosity to the level of the IM canal where the endosteal borders became parallel. Measurements started at the metaphysis, and then proceeded 25 and 50 mm distal to the metaphysis followed by 10 mm increments thereafter. Each level was compared to the level above with t tests in the overall cohort and separately by sex. Height was correlated to ML-AP difference and IM diameter with Pearson correlation coefficient. Potential stem sizes that extended 50, 60, 70, and 80 mm from the metaphysis were analyzed to record the percentage of patients in whom the stem would reach past the TP.

Results

The mean TP for all patients was 55.6 ± 7.4 mm (37.5-78.4) from the greater tuberosity, 53.3 ± 6.6 mm (37.5-67.0) in females and 58.1 ± 7.5 mm (41.9-78.4) in males. ML and AP distances and IM diameter became consistent at level 3 (mean, 83 mm distal to the greater tuberosity) in the overall cohort and in both sexes. Height positively correlated with IM diameter. Males had significantly larger IM diameters compared to females at all levels. Cortical thickness remained relatively consistent throughout the proximal humerus. A stem length of 70 mm would extend past the TP in 98% of patients.

Conclusion

Humeral implants in RSA with a stem of at least 70 mm in length would extend distally past the TP in the majority of cases regardless of sex. At this point, the canal's area remains consistent which would facilitate diaphyseal fixation if required.

Latissimus Dorsi and Teres major tendon transfer increases internal rotation torque following lateralized reverse shoulder arthroplasty with subscapularis insufficiency

INTRODUCTION

Limitation of active Internal Rotation (IR) following Reverse Shoulder Arthroplasty (RSA) in patients with massive Rotator Cuff Tears (mRCTs) with subscapularis insufficiency remains a challenge. Recently, RSA with Latissimus dorsi and Teres major (LDTM) transfer in patients with limited active IR has been demonstrated as a reliable treatment option. The purpose of this study was to biomechanically compare the IR torque following LDTM transfer with RSA in mRCT with subscapularis insufficiency to RSA without tendon transfer.

METHODS

Eight cadaveric shoulders were tested (mean age: 64.5 ± 1.9 years) using a custom shoulder testing system that permits loading conditions of mRCT with subscapularis insufficiency. Two conditions were tested and compared. The first condition was RSA alone and the second condition was RSA with LDTM transfer. RSA with a medialized glenoid and lateralized humerus design was used for all specimens. The specimens were tested at 0°, 20° and 40° abduction at three different muscle loads: baseline, double, and triple, while the Teres minor and deltoid loads were kept constant. IR torque was measured with a torque wrench at 0°, 20°, and 40° abduction and 60° and 45° IR positions. Force required for anterior dislocation was measured at 20° abduction and 10° IR position.

RESULTS

RSA with LDTM transfer had significantly higher IR torque at all abductions and muscle loading compared with RSA without transfer (average at all positions; RSA without transfer: 0.80 ± 0.02 Nm, LDTM transfer for all loads: 1.43 ± 0.10 Nm). RSA with LDTM transfer (91.4 ± 3.9 N) needed higher force for anterior dislocation compared to RSA alone (89.4 ± 4.1 N), but there was no significant difference.

CONCLUSION

LDTM transfer with RSA increases IR torque compared to RSA without tendon transfer in a cadaveric model. LDTM transfer with RSA may be a reliable treatment option for patients with mRCT and subscapularis insufficiency who are expected to have limited active IR following RSA.

Subacromial notching after reverse total shoulder arthroplasty

BACKGROUND

Scapular notching is a well-known postoperative complication of reverse total shoulder arthroplasty (RTSA). However, subacromial notching (SaN), a subacromial erosion caused by repeated abduction impingement after RTSA, has not been previously reported in a clinical setting. Therefore, this study aimed to assess the risk factors and functional outcomes of SaN after RTSA.

METHODS

We retrospectively reviewed the medical records of 125 patients who underwent RTSA with the same design between March 2014 and May 2017 and had at least 2 years of follow-up. SaN was defined as subacromial erosion observed at the final follow-up but not on the X-ray 3 months after surgery. Radiologic parameters representing the patient's native anatomy and degrees of lateralization and/or distalization during surgery were evaluated using preoperative and 3 months postoperative X-rays. The visual analogue scale of pain, active range of motion, and American Shoulder and Elbow Surgeons score were assessed preoperatively and at the final follow-up to evaluate the functional outcomes of SaN.

RESULTS

SaN occurred in 12.8% (16/125) of enrolled patients during the study period. Preoperative center of rotation-acromion distance (P = .009) and postoperative humerus lateralization offset, which evaluated the degree of lateralization after RTSA (P = .003), were risk factors for SaN. The preoperative center of rotation-acromion distance and postoperative humerus lateralization cutoff values were 14.0 mm and 19.0 mm, respectively. The visual analogue scale of pain (P = .01) and American Shoulder and Elbow Surgeons score (P = .04) at the final follow-up were significantly worse in patients with SaN.

CONCLUSIONS

SaN might adversely affect postoperative clinical outcomes. As SaN correlated with patients' anatomical characteristics and degree of lateralization during RTSA, the implant's degree of lateralization should be adjusted according to the patient's own anatomical characteristics.

Long-Term Results of Primary Reverse Shoulder Arthroplasty for Massive, Irreparable Rotator Cuff Tears Without Glenohumeral Arthritis with a Mean Follow up of 9.4 Years

Background

The aim of this single-center study was to analyze the long-term clinical results of reverse shoulder arthroplasty in patients with massive, irreparable rotator cuff tears without glenohumeral arthritis.

Methods

A retrospective cohort study of 105 patients (115 shoulders) was conducted. The mean age of the patient group was 76 years (range, 65 to 87 years). The mean clinical follow-up was 9.4 years (range, 5 to 17 years). Pain, range of motion, and complication rates were analyzed pre-operatively and at the last follow-up.

Results

The mean Constant-Murley score increased from 29 points (range, 21 to 34 points) preoperatively to 68.1 points (range, 57 to 81 points) postoperatively (p<0.05). Scapular notching was present in 50 shoulders (43.5%) and it was grade 1 or 2 in 47 of 115 cases (40.9%) and grade 3 or 4 in 3 of 115 cases (2.6%). Complications occurred in 19 patients (17%). Seven patients (6%) underwent revision surgery. The mean satisfaction rate was 94%.

Conclusions

Reverse shoulder arthroplasty is a viable treatment for massive, irreparable rotator cuff tears without glenohumeral arthritis with satisfactory clinical outcomes and low complication and reoperation rates with a mean follow up of 9.4 years after surgery.

Spontaneous Deltoid Tear in Cuff Tear Arthropathy and Its Effect on the Outcome of Reverse Total Shoulder Arthroplasty: A Comparison Using Propensity Score Matching

Background

Deltoid function critically influences the results of reverse total shoulder arthroplasty (RTSA), and spontaneous deltoid attrition tears are frequently detected in cuff tear arthropathy (CTA) patients; however, the clinical impacts of these tears on RTSA outcomes are undetermined. Our aim was to determine the effect of spontaneous deltoid attrition tears on postoperative outcomes after RTSA without an additional deltoid procedure.

Methods

Seventy-two patients who underwent RTSA for CTA with preoperative magnetic resonance imaging (MRI) and a minimum clinical follow-up of 1 year (mean, 32 months) were retrospectively reviewed in the study. Patients with a history of previous shoulder surgery or injury were excluded. The presence and location of deltoid attrition tears were determined in preoperative MRI. Propensity score matching (1:1) was performed to construct tear and no-tear groups. Finally, 21 patients, matched with respect to age, sex, hand dominance, symptom duration, medical comorbidity (obesity, diabetes mellitus, and coronary artery disease), Hamada grade, and implant type, were assigned to each group. Clinical outcomes (functional scores, isometric power, and range of motion) in the two groups were compared.

Results

Deltoid attrition tears were detected in 21 of the 72 enrolled cases (29.1%). Anterolateral deltoid was the most frequent location and no tear was detected in the posterior deltoid. The tear rate increased with disease severity (Hamada G2, 4.8%; G3, 23.8%; > G4, 71.4%). No pre- or postoperative clinical variables differed significantly between the tear and no tear groups.

Conclusions

Deltoid attrition tears were detected in 29% of CTA patients who underwent RTSA. The most common site was the anterolateral region and tear prevalence tended to increase with CTA progression. However, RTSA was found to provide satisfactory outcomes regardless of the presence of a deltoid attrition tear.

Outcomes of Reverse Total Shoulder Arthroplasty with Latissimus Dorsi Tendon Transfer for External Rotation Deficit: A Systematic Review and Meta-Analysis

BACKGROUND

Latissimus dorsi transfer (LDT) has been purported to restore motion in patients undergoing reverse shoulder arthroplasty (RSA) who have preoperative combined loss of forward elevation (FE) and external rotation (ER). This systematic review summarizes the available evidence for the functional outcomes and complications after RSA with LDT. Furthermore, the effect of implant design and whether a concomitant teres major transfer (TMT) was performed were studied.

METHODS

A systematic review was performed per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We queried PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify articles reporting on LDT with RSA to restore ER. Our primary outcomes were ER, FE, Constant score, and complication incidence. Secondarily, we reported postoperative internal rotation (IR) and compared ER, FE, and Constant score based on lateralized versus medialized global implant design and whether concomitant TMT was performed.

RESULTS

Nineteen studies were evaluated; functional outcomes were assessed in 16 articles reporting on 258 RSAs (123 LDT, 135 LDT-TMT). Surgical indication was most commonly cuff tear arthropathy and massive irreparable cuff tear. Mean ER was -12° preoperatively and 25° postoperatively, FE was 72° preoperatively and 141° postoperatively. Mean postoperative Constant score was 65. Of 138 patients (8 studies) describing IR, only 25% reported a mean postoperative IR ≥L3. Subanalysis comparing lateralized versus medialized implants and whether TMT was concomitantly performed demonstrated no significant difference in postoperative ER, FE, and Constant score, nor preoperative to postoperative improvement in ER and FE. The complication rate was 14.1% (of 291 shoulders from 16 studies), including tear in the tendon transfer (n = 3), revision tendon repair (n = 1), nerve-related complication (n = 9), and dislocation (n = 9).

CONCLUSIONS

RSA with LDT is a reliable option to restore motion, with a comparable complication rate with standard RSA. The use of medialized versus lateralized implants and whether the TM was concomitantly transferred may not influence clinical outcomes.

LEVEL OF EVIDENCE

Level IV. See Instructions for Authors for a complete description of levels of evidence.

The Evolution of Reverse Total Shoulder Arthroplasty-Where Do We Stand and What Comes Next?

Over 35 years ago, the pioneer Paul Grammont from Lyon published his ideas of a reversed semi-constraint prosthesis improving the moment arm of the deltoid by medializing the center of rotation and lengthening of the arm and thus increasing deltoid muscle tension [...].

Challenges for Optimization of Reverse Shoulder Arthroplasty Part I: External Rotation, Extension and Internal Rotation

A detailed overview of the basic science and clinical literature reporting on the challenges for the optimization of reverse shoulder arthroplasty (RSA) is presented in two review articles. Part I looks at (I) external rotation and extension, (II) internal rotation and the analysis and discussion of the interplay of different factors influencing these challenges. In part II, we focus on (III) the conservation of sufficient subacromial and coracohumeral space, (IV) scapular posture and (V) moment arms and muscle tensioning. There is a need to define the criteria and algorithms for planning and execution of optimized, balanced RSA to improve the range of motion, function and longevity whilst minimizing complications. For an optimized RSA with the highest function, it is important not to overlook any of these challenges. This summary may be used as an aide memoire for RSA planning.

Challenges for Optimization of Reverse Shoulder Arthroplasty Part II: Subacromial Space, Scapular Posture, Moment Arms and Muscle Tensioning

In part II of this comprehensive review on the optimization of reverse shoulder arthroplasty (RSA), we focus on three other challenges: 1. "Conservation of sufficient subacromial and coracohumeral space"; 2. "Scapular posture"; and 3. "Moment arms and muscle tensioning". This paper follows a detailed review of the basic science and clinical literature of the challenges in part I: 1. "External rotation and extension" and 2. "Internal rotation". "Conservation of sufficient subacromial and coracohumeral space" and "Scapular posture" may have a significant impact on the passive and active function of RSA. Understanding the implications of "Moment arms and muscle tensioning" is essential to optimize active force generation and RSA performance. An awareness and understanding of the challenges of the optimization of RSA help surgeons prevent complications and improve RSA function and raise further research questions for ongoing study.

Reverse shoulder arthroplasty using an onlay humeral prosthesis, offset humeral tray, and augmented glenoid baseplate: surgical technique and review of the impact of prosthesis design on scapular fractures following reverse shoulder arthroplasty

Reverse total shoulder arthroplasty (RSA) has become the most utilized form of arthroplasty of the shoulder. Acromial stress fractures and scapular spine stress fractures are rare, yet well-recognized complications of RSA with ongoing studies identifying whether patient factors or prosthetic designs serve as risk factors. Specifically, it remains unclear if or how the position of the humeral tray (inlay or onlay) in RSA affects rates of periscapular fractures. The purpose of this article is to describe our technique for RSA using an onlay prosthesis, a variable-offset humeral tray, and an augmented glenoid baseplate, as well as to review the published results of acromial and scapular spine fractures after RSA based on humeral implant design.

Comparison of Clinical Performance of Inlay versus Onlay Humerus Implants in Reverse Total Shoulder Arthroplasty

Background

Reverse total shoulder arthroplasty (RTSA) has become the treatment of choice for the management of massive rotator cuff tears combined with cuff tear arthropathy, and many novel designs have been proposed to overcome the shortcomings of classic RTSA. This study sought to evaluate and compare RTSA outcomes among patients with cuff tear arthropathy treated by a medialized inlay humerus implant with a neck shaft angle of 155° or a lateralized onlay implant with a neck shaft angle of 145°.

Methods

A retrospective review of 32 inlay implants and 32 onlay implants was performed. The active range of motion (ROM), visual analog scale (VAS) for pain, motor power for elevation and external rotation, and functional scores including the American Shoulder and Elbow Surgeons score, Constant score, and Korean Shoulder Scoring system were assessed before surgery, at 3, 6, and 12 months after surgery, and at the last follow-up at least 24 months after surgery. Scapular notching, lateral humeral offset, and deltoid wrapping offset were assessed for radiographic evaluation.

Results

The preoperative demographic data of both groups showed no significant differences (p > 0.05). The mean follow-up period was 24.9 months. Significant improvements in forward flexion, functional scores, and pain VAS score were observed in both groups at the last follow-up. No significant differences in ROM or functional scores were found between two groups at each time point, except that the onlay implant group exhibited a significantly greater range of external rotation at 3 and 12 months after surgery and at the last follow-up. The rate of scapular notching and the final power improvement did not show significant differences between the groups.

Conclusions

Primary RTSA using inlay or onlay humerus implants was associated with recovery from pseudoparalysis and good clinical outcomes. However, RTSA with onlay humerus implantation led to clinically superior results in terms of external rotation.