Lateralized vs. classic Grammont-style reverse shoulder arthroplasty for cuff deficiency Hamada stage 1-3: does the design make a difference?

Clinical and radiological comparison of three different reverse shoulder arthroplasty designs for patients with primary osteoarthritis

AIMS

In reverse shoulder arthroplasty (RSA), different implant designs range from medializing implants to strongly lateralizing onlay designs with different neck-shaft-angles (NSA). Thus different degrees of lateralization are currently used. Aim of this study was to compare clinical and radiological outcomes of three different implant designs in a homogeneous patient cohort with primary osteoarthritis (OA).

METHODS

Patients with OA who underwent RSA between 03/2014 and 01/2020 were included and categorized into three groups based on RSA design: group MD (medialized-distalized design: eccentric glenosphere, 155° NSA), group L (lateralized design: + 4 mm centric glenosphere, 135° NSA), group LD (lateralized-distalized design: eccentric glenospheres, + 3 mm baseplate, curved onlay stem 145° NSA). Inclusion criteria were complete clinical and radiological 24 months follow-up (FU) including range of motion (ROM), Constant-Murley score (CS), Subjective Shoulder Value (SSV). In addition, scapular notching and adverse events were recorded.

RESULTS

Group MD including 26 patients (81% female; mean age: 77.9 years) reached 71 (range: 60-85) points in CS and 90% (range: 40-100) in SSV. In group L, 46 patients (98% female; mean age: 75.2 years) achieved a CS of 75 (59-85) points and SSV was 95% (60-100). In group LD, 25 patients (68% female; mean age: 76.3 years) presented a CS of 79 (30-100) points and SSV of 93% (50-100). Group L and group LD achieved significantly better abduction, internal and external rotation (p < 0.001), forward flexion (p = 0.023) and SSV (p = 0.046). Scapular notching was present in 22% of MD patients (13% grade 1; 4% grade 2; 4% grade 4), 16% in group L (all grade 1) and 9% in group LD (all grade 2). No prosthesis related complication occurred in any group.

CONCLUSION

In patients with primary OA, the lateralized and lateralized-distalized designs result in superior subjective satisfaction in SSV and improved ROM in all planes compared to the traditional distalized-medialized implant designs. In all three groups, no implant related complications were noted.

Mid-Term Outcomes of a Rectangular Stem Design with Metadiaphyseal Fixation and a 135° Neck-Shaft Angle in Reverse Total Shoulder Arthroplasty

Background/Objectives: Classical reverse shoulder arthroplasty (RSA) with a high neck-shaft angle (NSA) of 155° has shown satisfactory outcomes. However, newer RSA designs aim to improve results by modifying the stem design. This study evaluates the 5-year outcomes of a stem design featuring a rectangular metadiaphyseal fixation and a 135° NSA. Methods: This prospective bicentric case series included and longitudinally followed up patients that were treated for cuff arthropathy, massive irreparable rotator cuff tears, or eccentric osteoarthritis using a non-cemented rectangular metadiaphyseal fixation stem with a 135° NSA (Univers Revers, Arthrex, Naples, FL, USA). Subjective and objective functional outcome scores (Constant-Murley Score (CS), Shoulder Pain and Disability Index (SPADI), and Subjective Shoulder Value (SSV)), range of motion (ROM), radiographic outcome, adverse events, complications, and quality of life were investigated. Results: This study enrolled 132 patients (59% female, mean age 75 years, SD 6). At the 5-year follow-up, subjective and objective outcomes significantly improved compared to baseline: CS (32.9 to 71.7, p < 0.001), SPADI (38.7 to 86.2, p < 0.001), and SSV (43.0 to 84.1, p < 0.001). ROM improved in flexion (80° to 142.4°, p < 0.001), abduction (71.5° to 130.2°, p < 0.001), internal rotation (p < 0.001), internal rotation at 90° abduction (12.7° to 45.0°, p < 0.001), and abduction strength (0.8 kg to 5.2 kg, p < 0.001). External rotation remained unchanged (32.1° to 32.0°, p = 0.125), but external rotation at 90° abduction improved (20.9° to 52.7°, p < 0.001). No signs of implant migration, subsidence, shift, tilt, alignment loss, or wear were observed, but scapular bone spur formation (11%), scapular notching grade 1 (10%), bone resorption (10%), and partial humeral radiolucent lines (1%) were reported. Conclusions: Rectangular stems with metadiaphyseal fixation and a 135° neck-shaft angle in RSA consistently improve shoulder function, showing no aseptic loosening and minimal radiological changes at 5 years.

Optimizing post-surgical outcomes: unveiling the importance of patient-reported outcomes with insights from the schulthess local shoulder arthroplasty registry

OBJECTIVE

The establishment of clinical registries is essential for the comprehensive evaluation of surgical outcomes. In 2006, the Schulthess Shoulder Arthroplasty Registry (SAR) was launched to systematically assess safety, implant longevity, functional outcomes, pain levels, quality of life, and patient satisfaction in individuals undergoing shoulder arthroplasty. This paper aims to outline the registry data and demonstrate how it is leveraged to improve clinical outcomes. Additionally, we provide guidance for organizations currently collecting or planning to collect similar data.

PARTICIPANTS

Our SAR systematically records adult patients' data undergoing either anatomic or reverse shoulder joint replacement at the Schulthess Clinic. Both primary and revision surgeries are comprehensively documented within the registry.

CURRENT OUTCOMES

From March 2006 to December 2023, the SAR included 98% of eligible operations. A total of 2301 patients were recruited, accounting for 3576 operations and 14,487 person-years of follow-up. At baseline, the mean age was 71 (range: 20-95), with 65% being female patients. The most prevalent indication was cuff tear arthropathy (46%), and the mean preoperative Constant Score was (31 ± 15). Notably, functional recovery peaked at 12 months postoperatively, displaying no clinically significant deterioration during the initial ten follow-up years in the overall cohort (including both primary arthroplasty and revisions). The registry has been instrumental in addressing various clinical and methodological inquiries, focusing particularly on comparing different implant configurations and surgical techniques to optimize functional recovery. Additionally, SAR data played a pivotal role in substantiating the clinical significance and reliability of radiological monitoring for cortical bone resorption, scapular notching, and glenoid component loosening.

Lateralization of the humerus in reverse total shoulder arthroplasty: can preoperative planning software predict postoperative lateralization and does lateralization influence outcomes?

BACKGROUND

Reverse total shoulder arthroplasty (RTSA) can result in varying amounts of humeral medialization or lateralization. The amount of medial or lateral change-in-arm-position can be predicted using 3D computed tomography planning software. It is not clear if the preoperatively predicted change-in-arm-position correlates with the actual radiographically measured change-in-arm-position or if the predicted or actual change-in-arm-position correlates with patient-reported outcomes or complications.

METHODS

Patients who received RTSA underwent preoperative 3D computed tomography planning to predict the postoperative medial-to-lateral change-in-arm-position (PCAP). Preoperative and postoperative radiographs were used to calculate the actual medial-to-lateral change-in-arm-position using the measurement of the lateral edge of the greater tuberosity to the lateral edge of the acromion (RCAP-LHO). The Western Ontario Osteoarthritis Score (WOOS), American Shoulder and Elbow Surgeons score (ASES), and Single Assessment Numeric Evaluation (SANE) were recorded at baseline, 1 year, and 2 years. Rates of complications were recorded.

RESULTS

A total of 250 patients were eligible for this study including 189 patients reaching the 1-year clinical follow-up point and 144 patients reaching the 2-year clinical follow-up point. One-year and 2-year follow-up rates were 89% and 91%, respectively. The mean PCAP was 3 ± 5 mm and the mean RCAP-LHO was 1 ± 8 mm. There was a moderate correlation between PCAP and RCAP-LHO. There was a weak correlation between increased PCAP lateralization and higher WOOS and ASES at 2 years and an improvement from baseline to 2 years in WOOS. There was a very weak correlation between increased PCAP lateralization and improvement compared with baseline in 1-year SANE and improvement compared with baseline in 2-year SANE. There was a weak correlation between lateralized RCAP-LHO and 2-year postoperative SANE. There was superior 2-year WOOS, ASES, and SANE, and improvement in SANE at 1 year compared with baseline in patients with a lateralized PCAP compared with a medialized or neutral PCAP. There was superior 2-year WOOS, improvement in WOOS from baseline to 2-year follow-up, and 2-year SANE in patients with a lateralized RCAP-LHO compared with a medialized or neutral RCAP-LHO. Overall complication rates were similar between groups although the dislocation rate in shoulders with a lateralized change-in-arm-position was significantly less than that in shoulders with a medial or neutral change-in-arm-position.

CONCLUSIONS

PCAP correlated with actual RCAP-LHO. Correlations exist with increased humeral lateralization and improved patient-determined outcomes. Patient-determined outcomes in patients with a lateralized change-in-arm-position were the same as or better than those with a medialized or neutral change-in-arm-position. A lateralized change-in-arm-position did not result in increased overall complications and was protective against postoperative instability.

Scapulothoracic orientation has a significant influence on the clinical outcome after reverse total shoulder arthroplasty

BACKGROUND

Computer simulation has indicated a significant effect of scapulothoracic orientation and posture on range of motion (ROM) after reverse total shoulder arthroplasty (RTSA). We analyzed this putative effect on the clinical and radiologic outcome post-RTSA.

METHODS

We retrospectively assessed 2-year follow-up data of RTSA patients treated at our clinic between 2008 and 2019. Patients were categorized into posture types A, B, and C based on an established method using scapular internal rotation on preoperative cross-sectional imaging. We compared differences in clinical ROM, pain, Subjective Shoulder Value, Constant Score, Shoulder Pain and Disability Index (SPADI), quality of life (EuroQol-5 Dimensions-5 Level utility index), and radiologic outcomes between posture types using linear regression analyses.

RESULTS

Of 681 included patients, 225 had type A posture, 326 type B, and 130 type C. Baseline group characteristics were comparable, although the type C group had a higher proportion of females (60% [A], 64% [B], 80% [C]) with lower abduction strength (0.7 kg [A], 0.6 kg [B], 0.3 kg [C]) and a slightly higher proportion with a Grammont design RTSA (41% [A], 48% [B], 54% [C]). There were significant adjusted differences in mean (±standard deviation) active flexion (A: 137° ± 21°; B: 136° ± 20°; C: 131° ± 19°) and passive flexion (A: 140° ± 19°; B: 138° ± 19°; C: 134° ± 18°), active (A: 127° ± 26°; B: 125° ± 26°; C: 117° ± 27°) and passive abduction (A: 129° ± 24°; B: 128° ± 25°; C: 121° ± 25°), SPADI (A: 81 ± 18; B: 79 ± 20; C: 73 ± 23), and pain (A: 1.2 ± 1.7; B: 1.6 ± 2.2; C: 1.8 ± 2.4) between posture types at 2 years (P ≤ .035). A higher distalization shoulder angle was associated with better abduction in type C patients (P = .016). Type C patients showed a trend toward a higher complication rate (3.9% vs. 1.1% [A], 3.2% [B]) (P = .067).

CONCLUSIONS

Type C posture influences the 2-year clinical outcome of RTSA patients in terms of worse flexion, abduction, SPADI, and pain. Scapulothoracic orientation and posture should be considered during the patient selection process, preoperative planning, and implantation of an RTSA.

Lateralization and inclination angle in reverse arthroplasty-what do we know?

Since the original Grammont design of a reverse shoulder arthroplasty there has been a trend to decrease inclination angle from 155° to 145 or 135°. Furthermore, lateralization on the glenoid side has been advocated. These changes decrease the risk for impingement between humerus and the inferior part of the glenoid (notching). These changes were also made to improve restoration of rotation. However, there is very little evidence that rotation has improved due to these changes. A negative effect of lateralization is that it increases the risk for glenoid loosening. Furthermore, the stress on acromion increases which may lead to more acromion or scapula spine fractures. More randomized studies are needed to define optimal design of a reverse shoulder arthroplasty.

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.

The lateralization and distalization index is more reliable than angular radiographic measurements in reverse shoulder arthroplasty

BACKGROUND

The lateralization shoulder angle (LSA) and distalization shoulder angle (DSA) are used to reproducibly measure lateralization and distalization after reverse shoulder arthroplasty (RSA). However, LSA and DSA may not offer a precise measurement of humeral lateralization and distalization and this relationship has not been explored. The aim of this study was to evaluate the validity of these measurements and to propose new measurement methods to estimate implant lateralization and distalization.

METHODS

3D models were constructed from computed tomography (CT) scans of 30 patients using a software platform. For each patient 24 different RSA modifications were created, resulting in 720 different RSA configurations. For each configuration LSA and DSA angles as well as lateralization and distalization distances were measured. Moreover, for each configuration two new measurements were done: the lateralization index (LI) and distalization index (DI). Correlations of the lateralization and distalization parameters were evaluated between measurements.

RESULTS

Weak correlations were founded between LSA and lateralization (r = 0.36, p < 0.01), whereas moderate correlations were observed between LI and lateralization (r = 0.72, p < 0.01). No significant correlations were found between DSA and distalization (r = 0.17, p = 0.113). In contrast, moderate correlations were identified between DI and distalization (r = 0.69, p < 0.01).

CONCLUSION

LI and DI are more reliable methods to estimate implant lateralization and distalization compared to angular radiographic measurements. However, the prognostic significance in predicting clinical outcomes after RSA remains unknown.

Does glenoid inclination affect the anterior stability of reverse total shoulder arthroplasty? A biomechanical study

PURPOSE

The anterior stability of reverse total shoulder arthroplasty is affected by multiple factors. However, the effect of glenosphere inclination on stability has rarely been investigated, which is what this study aims to look into.

METHODS

Reverse shoulder arthroplasty was performed on 15 cadaveric human shoulders. The anterior dislocation forces and range of motion in internal rotation in the glenohumeral joint (primary measured parameters) were tested in a shoulder simulator in different arm positions and implant configurations, as well as with a custom-made 10° inferiorly inclined glenosphere. The inclination and retroversion of the baseplate as well as the distance between the glenoid and coracoid tip in two planes (secondary measured parameters) were evaluated on CT scans.

RESULTS

In biomechanical testing, the custom-made inclined glenosphere showed no significant influence on anterior stability other than glenoid lateralisation over all arm positions as well as the neck-shaft angle in two arm positions. The 6 mm lateralised glenosphere reduced internal rotation at 30° and 60° of glenohumeral abduction. In 30° of glenohumeral abduction, joint stability was increased using the 155° epiphysis compared with the 145° epiphysis. The mean inclination was 16.1°. The inclination was positively, and the distance between the glenoid and coracoid tip in the anterior-to-posterior direction was negatively correlated with anterior dislocation forces.

CONCLUSIONS

The custom-made inferiorly inclined glenosphere did not influence anterior stability, but baseplate inclination itself had a significant effect on stability.

Metallic Lateralized-Offset Glenoid Reverse Shoulder Arthroplasty

Background

Metallic lateralized-offset glenoid reverse shoulder arthroplasty (RSA) for cuff tear arthropathy combines the use of a metallic augmented baseplate with a metaphyseally oriented short stem design that can be applied at a 135° or 145° neck-shaft angle, leading to additional lateralization on the humeral side. Lateralization of the center of rotation decreases the risk of inferior scapular notching and improves external rotation, deltoid wrapping, residual rotator cuff tensioning, and prosthetic stability1-4. Metallic increased-offset RSA (MIO-RSA) achieves lateralization and corrects inclination and retroversion while avoiding graft resorption and other complications of bony increased-offset RSA (BIO-RSA)5-8. Reducing the neck-shaft angle from the classical Grammont design, in combination with glenoid lateralization, improves range of motion9,10 by reducing inferior impingement during adduction at the expense of earlier superior impingement during abduction2,11. Lädermann et al.12 investigated how different combinations of humeral stem and glenosphere designs influence range of motion and muscle elongation. They assessed 30 combinations of humeral components, as compared with the native shoulder, and found that the combination that allows for restoration of >50% of the native range of motion in all directions was a 145° onlay stem with a concentric or lateralized tray in conjunction with a lateralized or inferior eccentric glenosphere. In addition, the use of a flush-lay or a slight-onlay stem design (like the one utilized in the presently described technique) may decrease the risk of secondary scapular spine fracture13,14. The goal of this prosthetic design is to achieve an excellent combination of motion and stability while reducing complications.

Description

This procedure is performed via a deltopectoral approach with the patient in the beach-chair position under general anesthesia combined with a regional interscalene nerve block. Subscapularis tenotomy and capsular release are performed, the humeral head is dislocated, and any osteophytes are removed. An intramedullary cutting guide is placed for correct humeral resection. The osteotomy of the humeral head is performed in the anatomical neck with an inclination of 135° and a retroversion of 20° to 40°, depending on the anatomical retroversion. The glenoid is prepared as usual. The lateralized, augmented baseplate is assembled with the central screw and the baseplate-wedge-screw complex is placed by inserting the screw into the central screw hole. Four peripheral screws are utilized for definitive fixation. An eccentric glenosphere with inferior overhang is implanted. The humerus is dislocated, and the metaphysis is prepared. Long compactors are utilized for proper stem alignment, and an asymmetric trial insert is positioned before the humerus is reduced. Stability and range of motion are assessed. The definitive short stem is inserted and the asymmetric polyethylene is impacted, resulting in a neck-shaft angle of 145°. Following reduction, subscapularis repair and wound closure are performed.

Alternatives

BIO-RSA is the main alternative to MIO-RSA. Boileau et al.15 demonstrated satisfactory early and long-term outcomes of BIO-RSA for shoulder osteoarthritis. A larger lateral offset may also be achieved with a thicker glenosphere2,16. Mark A. Frankle developed an implant that addressed the drawbacks of the Grammont design: a lateralized glenosphere combined with a 135° humeral neck-shaft angle. The 135° neck-shaft angle provides lateral humeral offset, preserving the normal length-tension relationship of the residual rotator cuff musculature, which optimizes its strength and function. The lateralized glenosphere displaces the humeral shaft laterally, minimizing the potential for impingement during adduction2,9,17,18. The advantage of BIO-RSA and MIO-RSA over lateralized glenospheres is that the former options provide correction of angular deformities without excessive reaming, which can lead to impingement19.

Rationale

BIO-RSA has been proven to achieve excellent functional outcomes15,20,21; however, the bone graft can undergo resorption, which may result in early baseplate loosening. Bipolar metallic lateralized RSA is an effective strategy for achieving lateralization and correction of multiplanar defects while avoiding the potential complications of BIO-RSA6,7,22-24. MIO-RSA also overcomes another limitation of BIO-RSA, namely that BIO-RSA is not applicable when the humeral head is not available for use (e.g., humeral head osteonecrosis, revision surgery, fracture sequelae).

Expected Outcomes

A recent study evaluated the clinical and radiographic outcomes of metallic humeral and glenoid lateralized implants. A total of 42 patients underwent primary RSA. Patients were documented prospectively and underwent follow-up visits at 1 and 2 years postoperatively. That study demonstrated that bipolar metallic lateralized RSA achieves excellent clinical results in terms of shoulder function, pain relief, muscle strength, and patient-reported subjective assessment, without instability or radiographic signs of scapular notching23. Kirsch et al.25 reported the results of primary RSA with an augmented baseplate in 44 patients with a minimum of 1 year of clinical and radiographic follow-up. The use of an augmented baseplate resulted in excellent short-term clinical outcomes and substantial deformity correction in patients with advanced glenoid deformity. No short-term complications and no failure or loosening of the augmented baseplate were observed. Merolla et al.7 compared the results of 44 patients who underwent BIO-RSA and 39 patients who underwent MIO-RSA, with a minimum follow-up of 2 years. Both techniques provided good clinical outcomes; however, BIO-RSA yielded union between the cancellous bone graft and the surface of the native glenoid in <70% of patients. On the other hand, complete baseplate seating was observed in 90% of MIO-RSA patients.

Important Tips

When performing subscapularis tenotomy, leave an adequate stump to allow end-to-end repair.Tenotomize the superior part of the subscapularis tendon in an L-shape, sparing the portion below the circumflex vessels.As glenoid exposure is critical, perform a 270° capsulotomy.Continuously check the orientation of the baseplate relative to the prepared hole and reamed surface to ensure accurate implantation of the full wedge baseplate to achieve a proper fit.Aim for 70% to 80% seating of the baseplate onto the prepared glenoid surface. Avoid overtightening or excessive advancement of the baseplate into the subchondral bone. Gaps between the baseplate and glenoid surface should also be avoided.In order to avoid varus or valgus malpositioning of the final implant, obtain proper diaphyseal alignment by following "the three big Ls": large, lateral, and long. Use a large metaphyseal component to fill the metaphysis. Place the guide pin for the reaming of the metaphysis slightly laterally into the resected surface of the humerus. Use long compactors for diaphyseal alignment to avoid varus or valgus malpositioning of the final implant.Use an intramedullary cutting guide for correct humeral resection.Utilize the correct liner in order to obtain proper tensioning and avoid instability.

Acronyms and Abbreviations

K wire = Kirschner wireROM = range of motion.

Biomechanical Characteristics of Glenosphere Orientation Based on Tilting Angle and Overhang Changes in Reverse Shoulder Arthroplasty

Background

Glenoid position and inclination are important factors in protecting against scapular notching, which is the most common complication that directly affects the longevity of reverse shoulder arthroplasty (RSA). This study aimed to investigate the biomechanical characteristics of glenosphere orientation, comparing neutral tilt, inferior overhang with an eccentric glenosphere at the same placement of baseplate, and inferior tilt after 10° inferior reaming in the lower part of the glenoid in RSA.

Methods

Nine cadaveric shoulders were tested with 5 combinations of customized glenoid components: a centric glenosphere was combined with a standard baseplate (group A); an eccentric glenosphere to provide 4-mm inferior overhang than the centric glenosphere was combined with a standard baseplate (group B); a centric glenosphere was combined with a wedge-shaped baseplate tilted inferiorly by 10° with the same center of rotation (group C); an eccentric glenosphere was attached to a wedge-shaped baseplate (group D); and 10° inferior reaming was performed on the lower part of the glenoid to apply 10° inferior tilt, with a centric glenosphere secured to the standard baseplate for simulation of clinical tilt (group E). Impingement-free angles for adduction, abduction, forward flexion, external rotation, and internal rotation were measured. The capability of the deltoid moment arm for abduction and forward flexion, deltoid length, and geometric analysis for adduction engagement were evaluated.

Results

Compared with neutral tilt, inferior tilt at the same position showed no significant difference in impingement-free angle, moment arm capability, and deltoid length. However, group D resulted in better biomechanical properties than a central position, regardless of inferior tilt. Group E demonstrated a greater range of adduction, internal and external rotation, and higher abduction and forward flexion capability with distalization, compared to corresponding parameters for inferior tilt with a customized wedge-shaped baseplate.

Conclusions

A 10° inferior tilt of the glenosphere, without changing the position of the baseplate, had no benefit in terms of the impingement-free angle and deltoid moment arm. However, an eccentric glenosphere had a significant advantage, regardless of inferior tilt. Inferior tilt through 10° inferior reaming showed better biomechanical results than neutral tilt due to the distalization effect.

[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.

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.

Medium-term results of inlay vs. onlay humeral components for reverse shoulder arthroplasty: a New Zealand Joint Registry study

BACKGROUND

The purpose of this study was to compare medium-term results of inlay and onlay humeral components in reverse shoulder arthroplasty (RSA). Specifically, we report differences in revision rate and functional outcomes between the 2 designs.

METHODS

The 3 most used inlay (in-RSA) and onlay (on-RSA) implants by volume from the New Zealand Joint Registry were included in the study. In-RSA was defined as having a humeral tray that recessed within the metaphyseal bone, whereas on-RSA was defined as having a humeral tray that rested on the epiphyseal osteotomy surface. The primary outcome was revision up to 8 years postsurgery. Secondary outcomes included the Oxford Shoulder Score (OSS), implant survival, and revision cause for in-RSA and on-RSA as well as individual prostheses.

RESULTS

There were 6707 patients (5736 in-RSA; 971 on-RSA) included in the study. For all causes, in-RSA demonstrated a lower revision rate compared to on-RSA (revision rate/100 component years: in-RSA 0.665, 95% confidence interval [CI] 0.569-0.768; on-RSA 1.010, 95% CI 0.673-1.415). However, the mean 6-month OSS was higher for the on-RSA group (mean difference 2.20, 95% CI 1.37-3.03; P < .001). However, this was not clinically significant. At 5 years, there were no statistically or clinically significant differences between the 2 groups with respect to the OSS.

CONCLUSION

The medium-term survival of in-RSA was higher than that of on-RSA. However, functional outcomes at 6 months were better for on-RSA compared to in-RSA. Further follow-up is required to understand the long-term survivorship and functional outcomes between these designs.

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.