Geometric modification of the humeral position after total reverse shoulder arthroplasty: what is the optimal lowering of the humerus?

Navigation in reverse shoulder arthroplasty: how the lateralization of glenosphere can affect the clinical outcome

INTRODUCTION

One of the main causes of RSA failure is attributable to the malpositioning of the glenoid component. Initial experiences with computer-assisted surgery have shown promising results in increasing the accuracy and repeatability of placement of the glenoid component and screws. The aim of this study was to evaluate the functional clinical results, in terms of joint mobility and pain, by correlating them with intraoperative data regarding the positioning of the glenoid component. The hypothesis was that the lateralization more than 25 mm of the glenosphere can led to better stability of the prosthesis but should pay in term of a reduced range of movement and increased pain.

MATERIALS AND METHODS

50 patients were enrolled between October 2018 and May 2022; they underwent RSA implantation assisted by GPS navigation system. Active ROM, ASES score and VAS pain scale were recorded before surgery. Preoperative data about glenoid inclination and version were collected by pre-op X-Rays an CT. Intraoperative data-inclination, version, medialization and lateralization of the glenoid component-were recorded using computer-assisted surgery. 46 patients had been further clinically and radiographically re-evaluated at 3-months, 6-months, 1-year, and 2-years follow-up.

RESULTS

We found a statistically significant correlation between anteposition and glenosphere lateralization value (DM - 6.057 mm; p = 0.043). Furthermore a statistically significant correlation has been shown between abduction movement and the lateralization value (DM - 7.723 mm; p = 0.015). No other statistically significant associations were found when comparing the values of glenoid inclination and version with the range of motion achieved by the patients after reverse shoulder arthroplasty.

CONCLUSION

We observed that the patients with the best anteposition and abduction results had a glenosphere lateralization between 18 and 22 mm. When increasing the lateralization above 22 mm or reducing it below 18 mm, on the other hand, both movements considered decreased their range.

LEVEL OF EVIDENCE

Level IV; Case Series; Treatment Study.

Preoperative Planning for Reverse Shoulder Arthroplasty: Does the Clinical Range of Motion Match the Planned 3D Humeral Displacement?

INTRODUCTION

The functional outcome after reverse shoulder arthroplasty (RSA) is closely linked to how much the humerus shifts because of the implants. While two-dimensional (2D) angle measurements have been used to capture this shift, it can be measured in three dimensions (3D) as the arm change position (ACP). In a previous study, the ACP was measured using 3D preoperative planning software with the passive virtual shoulder range of motion obtained after RSA. The main objective of this study was to evaluate the relationship between the ACP and the actual active shoulder range of motion measured after RSA. The hypothesis was that the ACP and the active clinical range of motion are related such that the ACP is a reliable parameter to guide the preoperative planning of an RSA. The secondary objective was to assess the relationship between 2D and 3D humeral displacement measurements.

MATERIALS AND METHODS

This prospective observational study enrolled 12 patients who underwent RSA and had a minimum follow-up of 2 years. The active range of motion in shoulder flexion, abduction, and internal and external rotation was measured. At the same time, ACP measurements were taken from a reconstructed postoperative CT scan, in addition to the radiographic measurements of humeral lateralization and distalization angles on AP views in neutral rotation.

RESULTS

The mean humeral distalization induced by RSA was 33.3 mm (±3.8 mm). A non-statistically significant increase in shoulder flexion was observed for humeral distalization beyond 38 mm (R² = 0.29, p = 0.07). This "threshold" effect of humeral distalization was also observed for the gains in abduction, as well as internal and external rotations, which seemed better with less than 38 mm or even 35 mm distalization. No statistical correlation was found between the 3D ACP measurements and 2D angle measurements.

CONCLUSION

Excessive humeral distalization seems to be detrimental to joint mobility, especially shoulder flexion. Humeral lateralization and humeral anteriorization measured using the ACP seem to promote better shoulder range of motion, with no threshold effect. These findings could be evidence of tension in the soft tissues around the shoulder joint, which should be taken into consideration during preoperative planning.

How common is nerve injury after reverse shoulder arthroplasty? A systematic review

BACKGROUND

Nerve injury following reverse shoulder arthroplasty (RSA) is a known risk factor with wide ranging incidences reported. This systematic review evaluates the overall incidence of nerve injury following primary and revision RSA and summarizes the characteristics of the nerve injuries reported in the current literature.

METHODS

A systematic review was performed using separate database searches (Pubmed, Embase, Web of Science, Cochrane) following the PRISMA guidelines. Search criteria included the title terms "reverse shoulder," "reverse total shoulder," "inverted shoulder," and "inverted total shoulder" with publication dates ranging from 01/01/2010 to 01/01/2022. Studies that reported neurological injuries and complications were included and evaluated for primary RSA, revision RSA, number of nerve injuries, and which nerves were affected.

RESULTS

After exclusion, our systematic review consisted of 188 articles. A total of 40,146 patients were included, with 65% female. The weighted mean age was 70.3 years. The weighted mean follow-up was 35.4 months. The rate of nerve injury after RSA was 1.3% (510 of 40,146 RSAs). The rate of injury was greater in revision RSA compared to primary RSA (2.4% vs. 1.3%). Nerve injury was most common in RSAs done for a primary diagnosis of acute proximal humerus fracture (4.0%), followed by cuff tear arthropathy (3.0%), DJD (2.6%), and inflammatory arthritis (1.7%). Massive rotator cuff tears and post-traumatic arthritis cases had the lowest nerve injury rates (1.0% and 1.4%, respectively). The axillary nerve was the most commonly reported nerve that was injured in both primary and revision RSA (0.6%), followed by the ulnar nerve (0.26%) and median nerve (0.23%). Brachial plexus injury was reported in 0.19% of overall RSA cases.

CONCLUSION

Based on current English literature, nerve injuries occur at a rate of 1.3% after primary RSA compared with 2.4% after revision RSA. The most common nerve injury was to the axillary nerve (0.64%), with the most common operative diagnosis associated with nerve injury after RSA being acute proximal humerus fracture (4.0%). Surgeons should carefully counsel patients prior to surgery regarding the risk of nerve injury.

The arm change position: Additional information for optimizing range of motion after reverse shoulder arthroplasty

INTRODUCTION

The arm change position (ACP) is a new parameter for evaluating the humerus' 3D displacement following reverse shoulder arthroplasty (RSA) during 3D pre operative planning. The purpose of this study was to analyze the relationship between ACP variations after RSA and simulated passive joint mobility. The assumption is that the ACP will to help optimize the passive joint mobility of a RSA implant.

METHODS

In 30 degenerative shoulders, four shoulder surgeons planned a RSA with virtual motion analysis. After this analysis, each plan was revised to optimize the range of motion. Relationships between the differences in movement amplitude and the differences in ACP were evaluated.

RESULTS

Arm lengthening and humerus lateralization were significantly associated with better joint mobility in all three planes (frontal, sagittal and axial). They were equally important for improving external rotation, extension, flexion and adduction. Anterior displacement of the humerus improved both internal and external rotation.

DISCUSSION

The ACP is a useful preoperative planning parameter for RSA. It could help with selecting the best implant combination, as well as determining their position, in order to optimize the simulated passive mobility relative to humerus displacement after RSA. To validate the value of the ACP in clinical practice, a prospective study is needed in which the postoperative joint mobility is measured in vivo as a function of the ACP.

LEVEL OF EVIDENCE

III, case control study.

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

BACKGROUND

Reverse shoulder arthroplasty (RSA) with a lateralized design is thought to improve outcomes. Our aim was to compare RSA with the classic Grammont prosthesis against a prosthesis with 135° inclination and a lateralized glenosphere for cuff-deficient shoulders.

METHODS

Patients with irreparable massive posterosuperior rotator cuff tear Hamada grade 1-3 underwent RSA and were documented prospectively up to 24 months postsurgery. Comparative RSA groups were "lateralized" (L), with 135° humeral inclination and 36+4-mm lateralized glenosphere (n = 44), and "Grammont" (G), with 155° humeral inclination and 36+2-mm eccentric glenosphere (n = 23). Range of motion including the Apley scratch test, abduction strength, Constant-Murley score (CS), and Shoulder Pain and Disability Index (SPADI) were assessed. Anteroposterior and axial radiographs were evaluated at 24 months, and additional measurements of scapular neck and glenoid anatomy, baseplate and glenosphere position, center of rotation, humeral offset, and lateralization and distalization shoulder angles were made. Linear regression and mixed models adjusted for sex differences and preoperative values were applied.

RESULTS

Overall CS and SPADI outcomes were not significantly different between groups (P ≥ .654). For group L, external rotation remained stable up to the 2-year follow-up and was higher than for group G (P = .012 ); a greater proportion of group L patients could reach the lumbar vertebra 3 (L3) (70% vs. 48% in group G) (P = .26). Group G had a higher inferior glenosphere overhang (P = .020) and center of rotation (COR) medialization (P < .001), whereas group L had higher humeral offset (P < .001) and lateralization shoulder angle (P < .001) with a trend toward higher baseplate positioning (P = .045). The rate of scapular notching was 2.9 times higher for group G than group L (P = .001).

CONCLUSION

RSA with 135° humeral inclination and a lateralized glenosphere shows similar outcome scores as the classic Grammont design but enables better preservation of external rotation and reduces the rate of scapular notching compared with the classic Grammont design in Hamada 1-3 patients with irreparable posterosuperior tears.

Radiographic geometry and clinical glenohumeral range of motion after reverse shoulder athroplasty, a retrospective cohort study

Background

The range of motion (ROM) in reverse shoulder arthroplasty (RSA), is mechanically limited by the surrounding bony obstacles especially in abduction and rotation planes. However, the clinical effect of implant positioning, prosthesis design, and individual differences in bone morphology, on ROM is obscure. The aim of this study was to investigate the correlation between radiographic geometry and clinical glenohumeral (GH) ROM after RSA.

Methods

RSA patients operated at Turku University Hospital during 2007–2013 were called for radiological and clinical follow-up. Pre- and postoperative true anteroposterior radiographs were obtained and the positioning of the center of rotation (COR) in relation to the surrounding bony structures was measured. Active and passive shoulder and GH abduction, flexion, internal and external rotation ROM were measured with goniometer. The Constant score (CS) and pain visual analogue scale (VAS) were recorded. The correlation between the radiographically measured parameters and the active and passive ROM and clinical outcome was statistically analyzed.

Results

91 shoulders were available for analyses with a mean follow-up of 38.7 months ± SD 20 (range 12–83) months. 77% of the patients were female, the mean age was 73 (SD 9) years. The mean angle between the line of supraspinatus fossa, and the line between COR and lateral edge of the acromion (α-angle) was 127° (SD 14) and the mean angle between the lines from lateral edge of the acromion to COR, and from there to the superior edge of the greater tubercle (β-angle) was 54° (SD 11). The mean active shoulder flexion at follow-up was 118° (SD 26), abduction 104° (SD 32), external rotation 41° (SD 22), internal rotation 77° (SD 21). The mean passive GH flexion was 80° (SD 19), abduction 67° (SD 15), external rotation 31° (SD 16) and internal rotation 34° (SD 14). The mean Constant score at follow-up was 53 (SD 18) and pain VAS 2 (SD 3). The positioning of the radiographically measured COR did not statistically significantly correlate with the ROM or clinical outcome scores.

Conclusions

Postoperative radiographically measured two-dimensional geometry and positioning of the COR does not significantly correlate with the glenohumeral range of motion or clinical results after RSA.

Level of evidence

Level 3, retrospective cohort study

Complications of reverse shoulder arthroplasty: a concise review

Reverse shoulder arthroplasty is an ideal treatment for glenohumeral dysfunction due to cuff tear arthropathy. As the number of patients treated with reverse shoulder arthroplasty is increasing, the incidence of complications after this procedure also is increasing. The rate of complications in reverse shoulder arthroplasty was reported to be 15%-24%. Recently, the following complications have been reported in order of frequency: periprosthetic infection, dislocation, periprosthetic fracture, neurologic injury, scapular notching, acromion or scapular spine fracture, and aseptic loosening of prosthesis. However, the overall complication rate has varied across studies because of different prosthesis used, improvement of implant and surgical skills, and different definitions of complications. Some authors included complications that affect the clinical outcomes of the surgery, while others reported minor complications that do not affect the clinical outcomes such as minor reversible neurologic deficit or minimal scapular notching. This review article summarizes the processes related to diagnosis and treatment of complications after reverse shoulder arthroplasty with the aim of helping clinicians reduce complications and perform appropriate procedures if/when complications occur.

Computer-Assisted Surgery in Reverse Shoulder Arthroplasty: Early Experience

BACKGROUND

In the last decade, new technologies have been applied to shoulder arthroplasty. The aim of this work was to show that navigated RSA allows the surgeon to reach the planned version/inclination in all cases. In this article are shown preliminary data, advantages, disadvantages and limits of the technique.

METHODS

Eighteen computer-assisted reverse shoulder arthroplasty were performed. Preoperative glenoid version and inclination were evaluated with preoperative CT scan using Orthoblue^® (Exactech, Gainesville, FL,USA) software, as well as baseplate type, planned glenoid component seating, planned postoperative version, planned postoperative inclination, intraoperative glenoid version/inclination, screw length and surgical time. A senior shoulder surgeon has analyzed the advantages, disadvantages and limitation of this kind of surgery.

RESULTS

Mean surgical time of the primary implants was 92 ± 12 min (min 75-max 110). Mean preoperative inclination was + 2.6° ± 6.4, mean preoperative version was - 7.6° ± 8.4. Mean planned postoperative inclination was - 2.7° ± 2.3, mean planned postoperative version was - 1.6° ± 2.9 and mean planned glenoid seating was 89% ± 8%. Planned settings were reached in all cases during surgery. Baseplate implanted were in nine cases 8° posterior augmented, in six cases standard and in three cases 10° superior augmented. Mean screw length was 33.5 mm ± 4.2 mm. No GPS system failure has been recorded. One coracoid fracture occurred during the first case.

DISCUSSION

Intraoperative navigation system is a reliable and user-friendly technology that allows the surgeon to reach planned glenoid positioning during surgery. Furthermore, this technology will allow the surgeon to compare clinical outcomes to component positioning data. The lack of humeral implant navigation is the main limit of this technique.

The modern reverse shoulder arthroplasty and an updated systematic review for each complication: part I

Background

Globally, reverse shoulder arthroplasty (RSA) has moved away from the Grammont design to modern prosthesis designs. The purpose of this 2-part study was to systematically review each of the most common complications of RSA, limiting each search to publications in 2010 or later. In this part (part I), we examined (1) scapular notching (SN), (2) periprosthetic infection (PJI), (3) mechanical failure (glenoid or humeral component), and (4) neurologic injury (NI).

Methods

Four separate PubMed database searches were performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Overall, 113 studies on SN, 62 on PJI, 34 on mechanical failure, and 48 on NI were included in our reviews. Univariate analysis was performed with the χ² or Fisher exact test.

Results

The Grammont design had a higher SN rate vs. all other designs combined (42.5% vs. 12.3%, P < .001). The onlay humeral design had a lower rate than the lateralized glenoid design (10.5% vs. 14.8%, P < .001). The PJI rate was 2.4% for primary RSA and 2.6% for revision RSA. The incidence of glenoid and humeral component loosening was 2.3% and 1.4%, respectively. The Grammont design had an increased NI rate vs. all other designs combined (0.9% vs. 0.1%, P = .04).

Conclusions

Focused systematic reviews of the recent literature with a large volume of RSAs demonstrate that with the use of non-Grammont modern prosthesis designs, complications including SN, PJI, glenoid component loosening, and NI are significantly reduced compared with previous studies. As the indications for RSA continue to expand, it is imperative to accurately track the rates and types of complications to justify its cost and increased indications.

Outcomes of reverse shoulder arthroplasty using a short stem through a superolateral approach

BACKGROUND

Reverse shoulder arthroplasties have progressed in recent decades to become the most popular type of arthroplasty. Short stems with metaphyseal fixation have been developed to preserve bone stock and facilitate possible revision. Accurate positioning of these implants can be challenging using the superolateral approach.

OBJECTIVE

This study aimed to evaluate the clinical and radiologic results of reverse short-stem arthroplasties using a superolateral approach with a minimum of 2 years' follow-up.

METHODS

Between January 2015 and December 2016, a total of 76 patients underwent reverse shoulder arthroplasty surgery (79 shoulders) using a short uncemented humeral stem for shoulder arthritis with irreparable rotator cuff tear. Arthroplasties for post-traumatic osteoarthritis were excluded. Functional outcomes were assessed using Constant Score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), visual analog scale (VAS), and range of motion. Radiographic analysis was used to evaluate component loosening, implant position, and implant filling ratio.

RESULTS

The mean age was 70.8 years. At a mean of 38.8-month follow-up, there were significant improvements in Constant score (44.2 to 87.9, P < .001), ASES score (36.2 to 84.3, P < .001), and VAS score (6.8 to 0.4, P < .001). Forward flexion improved from 89°to 131°(P < .001), and external rotation improved from 25° to 36°(P < .001). No evidence of periprosthetic loosening was visible. Mean varus of the humeral stem was 1°(±6°). The mean glenoidal inclination was 98°(±7°), which corresponds to a lower tilt of 8°. The average filling ratio was between 50% and 60% in both the metaphysis and the diaphysis.

CONCLUSION

The clinical results obtained in this study were satisfying, with a significantly low complication rate. Hence, short-stem reverse shoulder arthroplasty using a superolateral approach, while taking particular care to protect the deltoid, remains our method of choice.

Do short stems influence the cervico-diaphyseal angle and the medullary filling after reverse shoulder arthroplasties?

BACKGROUND

Shorter humeral stems were developed to improve bone preservation, vascularity and osteointegration in reverse total shoulder arthroplasty (RSA). While some studies examined the relationship between canal filling and radiographic changes, none evaluated the association between stem alignment and canal fill ratio (CFR).

HYPOTHESIS

The hypothesis was that stem misalignment after RSA would be associated with lower CFR.

PATIENTS AND METHODS

The authors retrospectively reviewed immediate postoperative radiographs of 157 patients, comprising 56 men (36%), who underwent RSA with a short uncemented stem with neck shaft angle (NSA) default of 145°. The parameters included postoperative NSA and metaphyseal CFR, both measured with excellent inter-observer agreement. Uni- and multivariable linear regressions were performed to determine associations between postoperative NSA and 5 variables (CFR, gender, age, BMI, and surgical approach).

RESULTS

Postoperative NSA was 149°±8°, exceeding 5° of varus in 15 shoulders (9%) and 5° of valgus in 60 shoulders (38%), and CFR was 58%±8%. CFR was lower in shoulders with varus stem alignment (54%±6%) than shoulders with neutral stem alignment (59%±8%, p=0.033). Multivariable regression revealed that postoperative NSA increased with age (beta: 0.20; p=0.008), was higher for shoulders operated with the subscapularis- and deltoid-sparing approach (beta: 3.82; p=0.040) but lower for men (beta: -4.14; p=0.002).

CONCLUSIONS

Stem misalignment exceeded 5° in 47% of the shoulders. Women, older age, and subscapularis- and deltoid-sparing approach are associated with greater risks of valgus stem positioning, while lower CFR seems to be associated with greater risks of varus stem positioning.

LEVEL OF EVIDENCE

IV; case series.

Effect of humeral stem and glenosphere designs on range of motion and muscle length in reverse shoulder arthroplasty

PURPOSE

To determine how different combinations of humeral stem and glenosphere designs for reverse shoulder arthroplasty (RSA) influence range of motion (ROM) and muscle elongation.

METHODS

A computed tomography scan of a non-pathologic shoulder was used to simulate all shoulder motions, and thereby compare the ROM and rotator cuff muscle lengths of the native shoulder versus 30 combinations of humeral components (1 inlay straight stem with 155° inclination and five onlay curved stems with 135°, 145° or 155° inclinations, using concentric, medialized or lateralized trays) and glenospheres (standard, large, lateralized, inferior eccentric and bony increased-offset (BIO-RSA)).

RESULTS

Only five of the 30 combinations restored ≥ 50% of the native ROM in all directions: the 145° onlay stem (concentric tray) combined with lateralized or inferior eccentric glenospheres and the 145° stem (lateralized tray) combined with either a large, lateralized or inferior eccentric glenosphere. Lengthening of the supraspinatus and infraspinatus, observed for all configurations, was greatest using onlay stems (7-30%) and BIO-RSA glenospheres (13-31%). Subscapularis lengthening was observed for onlay stems combined with BIO-RSA glenospheres (5-9%), while excessive subscapularis shortening was observed for the inlay stem combined with all glenospheres except the BIO-RSA design (> 15%).

CONCLUSIONS

The authors suggest implanting 145° onlay stems, with concentric or lateralized trays, together with lateralized or inferior eccentric glenospheres.