Impact of glenosphere size on clinical outcomes after reverse total shoulder arthroplasty: an analysis of 297 shoulders

Should the supraspinatus tendon be excised in the case of reverse shoulder arthroplasty for fracture?

PURPOSE

In the case of reverse shoulder arthroplasty (RSA) for proximal humeral fractures (PHFs) with tuberosity reconstruction, it is unclear whether the supraspinatus tendon continues to play a role. The aim of this study was to evaluate the clinical and radiological outcomes of RSA for PHFs in a large cohort of elderly patients and compare the results in the case of supraspinatus excision or preservation.

METHODS

In this retrospective multicentre study, 150 patients (mean age 77 years, 93% female) were reviewed and radiographed with a minimum follow-up of 24 months. The same Grammont prosthetic design was used in all cases (inclination angle 155°, non-lateralised glenosphere). Patients were divided into two groups: Group A (n = 117) underwent supraspinatus excision and Group B supraspinatus preservation (n = 33). Complications were recorded, and shoulder function, active mobility and subjective results were assessed.

RESULTS

At a mean follow-up of 59 months, there was no statistical difference in the complication rate (6% vs. 6.8%, p = 1), mean Constant score (61 points vs. 59 points, p = 0.52), simple shoulder value (74% vs. 73.9%, p = 0.9), active anterior elevation (125° vs. 128°, p = 0.45) and internal rotation (4.9 points vs. 4.1 points, p = 0.2). However, mean active external rotation was better in Group A (22° vs. 13°, p = 0.01). The greater tuberosity healing rate in satisfactory position did not differ statistically between the groups (68% vs. 55%, p = 0.14).

CONCLUSION

In the case of RSA with tuberosity reconstruction for acute PHFs, there is no clear evidence that supraspinatus preservation is advantageous.

Patient-reported outcomes of reverse total shoulder arthroplasty: a comparative risk factor analysis of improved versus unimproved cases

Background

The purpose of this study was to compare characteristics of patients who reported to be subjectively unimproved vs. improved after reverse total shoulder arthroplasty.

Methods

Data were derived from a prospective registry of patients who underwent reverse total shoulder arthroplasty with a minimum 2-year follow-up. Patients were asked to rate their subjective satisfaction and then divided into those who were unchanged or worse (unimproved group [UG]) vs. better or much better (improved group [IG]). The groups were compared for differences in demographic characteristics, preoperative factors, functional outcomes, and complications.

Results

There were 1425 patients in the IG and 134 patients in the UG. Patients in the IG were more likely to have a diagnosis of osteoarthritis. Patients in the UG were more likely to have coronary artery disease and diabetes and to have undergone prior surgery. No differences in implant configuration were found between groups. Preoperative measures for patients in the UG were worse for pain and function but not for range of motion. The outcomes in patients in the UG were worse for all postoperative measures, as well as for preoperative-to-postoperative improvement. Of the patients in the UG, 48% continued to have moderate to severe pain postoperatively. The complication rate was significantly higher in the UG.

Discussion

Up to 8.5% of patients rate themselves as unimproved after surgery. These patients are more likely to have certain comorbidities and to have undergone prior surgery. Although outcomes were significantly worse for all measures in the UG, improvement occurred in all measures despite patients subjectively being worse or unchanged. Residual pain and difficulty sleeping play a substantial role in subjective assessment of overall outcome.

How common are acromial and scapular spine fractures after reverse shoulder arthroplasty?: A systematic review

AIMS

Acromial fractures following reverse shoulder arthroplasty (RSA) have a wide range of incidences in reported case series. This study evaluates their incidence following RSA by systematically reviewing the current literature.

MATERIALS AND METHODS

A systematic review using the search terms "reverse shoulder", "reverse total shoulder", or "inverted shoulder" was performed using PubMed, Web of Science, and Cochrane databases between 1 January 2010 and 31 March 2018. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. Studies were included if they reported on RSA outcomes and the incidence rate of acromial and/or scapular spine fractures. The rate of these fractures was evaluated for primary RSA, revision RSA, RSA indications, and RSA implant design.

RESULTS

The review included 90 articles out of 686 identified after exclusions. The incidence rate of acromial and/or scapular spine fractures was 2.8% (253/9048 RSAs). The fracture rate was similar for primary and revision RSA (2.8% vs 2.1%; p = 0.4). Acromial fractures were most common after RSA for inflammatory arthritis (10.9%) and massive rotator cuff tears (3.8%). The incidence was lowest in RSA for post-traumatic arthritis (2.1%) and acute proximal humerus fractures (0%). Lateralized glenosphere design had a significantly higher rate of acromial fractures compared with medial glenosphere designs.

CONCLUSION

Based on current English literature, acromial and/or scapular spine fractures occur at a rate of 2.8% after RSA. The incidence is slightly more common after primary compared with revision arthroplasty. Also, higher rates of acromial fractures are reported in RSA performed for inflammatory arthritis and in the lateralized glenoid design. Cite this article: Bone Joint J 2019;101-B:627-634.

Acromial spine fracture after reverse total shoulder arthroplasty: a systematic review

BACKGROUND

Reverse total shoulder arthroplasty (RSA) accounts for nearly one-third of shoulder arthroplasty utilization nationally. The complication rate has increased concurrently. Consensus is lacking regarding the incidence, etiology, and treatment of acromial or scapular spine fractures after RSA. The purpose of our study was to perform a systematic review of the literature to analyze the occurrence and outcomes of this complication.

METHODS

The MEDLINE, Embase, Google Scholar, and Cochrane databases were queried in late 2017 for combinations of the words "acromial," "fracture," "reverse," "shoulder," and "arthroplasty." We included all studies that contained a clearly defined performance of RSA, acromial fracture(s) noted, and treatment (if any) and outcomes of treatment. The initial search yielded 50 studies; 32 met the inclusion criteria.

RESULTS

Among 3838 RSAs, 159 acromial fractures were reported, for an overall incidence of 4.14%; the mean time to diagnosis from surgery was 9 months (range, 1.3-24 months). Treatments included nonoperative treatment in a sling or abduction brace in 139 cases and open reduction-internal fixation in 20. Regardless of treatment, patients reported inferior function after fracture compared with initially after RSA. Forward flexion was 95° (range, 30°-110°), abduction was 76° (range, 30°-180°), the Constant score was 63 (range, 59-67.5), and the American Shoulder and Elbow Surgeons score was 57 (range, 7-83); all values were reduced compared with patients without fractures.

CONCLUSION

This study suggests the occurrence of acromial fractures after RSA is a common event, with a rate of over 4%. These fractures correlate with worse postoperative outcomes regardless of treatment method; open reduction-internal fixation was not shown to be clinically superior despite a limited complication rate. Additional high-quality studies addressing acromial spine fracture after RSA are needed.

Scapular Notching in Reverse Total Shoulder Arthroplasty

Scapular notching is a common radiographic finding occurring after reverse total shoulder arthroplasty, and it refers to an erosive lesion of the inferior scapular neck because of the impingement of the humeral implant during adduction. The clinical importance of notching is unclear, and the optimal treatment of severe notching is unknown. The incidence and severity of scapular notching is related to prosthetic design and surgical technique. Implant design factors include size, shape, and position of the glenosphere, inclination of the humeral neck-shaft angle, implant offset, and native scapular anatomy. Scapular notching may lead to deterioration of functional outcomes and glenoid implant loosening and failure. Lateral offset, inferior glenosphere overhang, and careful consideration of the presurgical glenoid morphology may help prevent scapular notching. Currently, there is limited evidence to direct the management of scapular notching, and further research is needed to elucidate optimal prevention and treatment strategies.

Reverse shoulder arthroplasty in recent proximal humerus fractures

Reverse shoulder arthroplasty is now the standard treatment for displaced, three- or four-part, proximal humeral fractures in patients older than 70 years. Inadequate tuberosity repair or inappropriate humeral stem position are associated with poorer outcomes, notably regarding rotation and stability. Strict operative technique during prosthesis implantation is therefore crucial to obtain reliable and reproducible outcomes. The objective of this article is to describe the surgical technique for reverse shoulder arthroplasty used to treat recent proximal humerus fractures.

Quantifying success after total shoulder arthroplasty: the substantial clinical benefit

BACKGROUND

An understanding of the substantial clinical benefit (SCB) after total shoulder arthroplasty (TSA) may help to gauge a minimum threshold beyond which a patient perceives his or her outcome as being substantially better. This study quantifies SCB for 7 outcome metrics and active motion measurements after shoulder arthroplasty and determines how these values vary based on prosthesis type, patient age at surgery, sex, and length of follow-up.

METHODS

A total of 1,568 shoulder arthroplasties with 2-year minimum follow-up were performed by 13 shoulder surgeons and enrolled in a multicenter registry. The SCB for the American Shoulder and Elbow Surgeons Shoulder Assessment, Constant Score, University of California Los Angeles Shoulder Rating Scale, Simple Shoulder Test, Shoulder Pain and Disability Index, global shoulder function, and visual analog scale pain scores, as well as active abduction, flexion, and external rotation were calculated for different patient cohorts using an anchor-based method.

RESULTS

The anchor-based SCB results were American Shoulder and Elbow Surgeons score, 31.5 ± 2.0; Constant Score, 19.1 ± 1.7; University of California Los Angeles Shoulder Rating Scale score, 12.6 ± 0.5; Simple Shoulder Test score,  3.4 ± 0.3; Shoulder Pain and Disability Index score,  45.4 ± 2.2; global shoulder function, 3.1 ± 0.2; visual analog scale, 3.2 ± 0.3; active abduction, 28.5° ± 3.1°; active forward flexion, 35.4° ± 3.5°; and active external rotation, 11.7° ± 1.9°. Anatomic TSA patients, male patients, and patients of longer follow-up duration were associated with higher SCB values than female patients, reverse TSA patients, and patients of shorter follow-up duration.

CONCLUSION

Our analysis demonstrated two-thirds of patients achieved the SCB threshold after TSA. Generally, a change of 30% of the total possible score for each outcome metric approximates or exceeds this SCB threshold.

Outcomes of reverse shoulder arthroplasty in small- and large-stature patients

BACKGROUND

As the worldwide use of reverse shoulder arthroplasty (RSA) increases, a range of implant sizes may be required to match regional and ethnic variation in patients' stature. Size-mismatched implants may possibly result in poorer surgical outcomes. The purpose of this study was to compare the outcomes of primary RSA in patients at the extreme ends of the growth curve with those in average-stature patients in the United States.

METHODS

A multicenter shoulder arthroplasty database was retrospectively reviewed to identify all primary RSAs using a single implant system with a minimum 2-year follow-up. Small patients were defined as the height of <155 cm, tall as >183 cm, and average as 162-178 cm. Active range of motion (ROM), visual analog scale pain score, and patient-reported outcomes (PROs) were compared among the 3 groups.

RESULTS

The study included 552 shoulders (130 small, 384 average, and 38 tall stature). Preoperatively, the average height group had significantly less ROM than the other groups, but there were no significant differences in postoperative ROM. This resulted in poorer improvements in postoperative ROM in the small and tall groups, with the small-stature patients having significantly less ROM improvement compared with average-stature patients. However, these differences did not result in poorer PROs between groups.

DISCUSSION

Small- and large-stature patients showed inferior improvements in ROM after RSA compared with average-stature patients. Our results suggest that current implants optimize ROM gains for average-stature patients and improve PROs independently of patient stature at a minimum 2-year follow-up.

Quantifying success after total shoulder arthroplasty: the minimal clinically important difference

BACKGROUND

Knowledge of the minimal clinically important difference (MCID) for different shoulder outcome metrics and range of motion after total shoulder arthroplasty (TSA) can be useful to establish a minimum threshold of improvement that defines successful treatment. This study quantifies how MCID varies with different prosthesis types, patient age, gender, and length of follow-up after TSA.

METHODS

A total of 466 anatomic TSA (aTSA) and reverse TSA (rTSA) with 2-year minimum follow-up were performed by 13 shoulder surgeons. The MCID for the American Shoulder and Elbow Surgeons, Constant, University of California Los Angeles Shoulder Rating Scale, Simple Shoulder Test, Shoulder Pain and Disability Index, global shoulder function, and visual analog scale for pain scores, as well as active abduction, forward flexion, and external rotation, were calculated for different prosthesis types and patient cohorts using an anchor-based method.

RESULTS

The anchor-based MCID results were American Shoulder and Elbow Surgeons = 13.6 ± 2.3, Constant score = 5.7 ± 1.9, University of California Los Angeles Shoulder Rating Scale = 8.7 ± 0.6, Simple Shoulder Test score = 1.5 ± 0.3, Shoulder Pain and Disability Index score = 20.6 ± 2.6, global shoulder function = 1.4 ± 0.3, pain visual analog scale  = 1.6 ± 0.3, active abduction = 7° ± 4°, active forward flexion = 12° ± 4°, and active external rotation = 3° ± 2°. Female gender and rTSA were associated with lower MCID values compared with male gender and aTSA patients.

CONCLUSION

The minimum improvement necessary for patients to achieve a result they believe is clinically meaningful after aTSA and rTSA is nominal and was achieved by at least 80% of the patients. Future endeavors should investigate the influence of different anchor questions on the MCID calculation.

Glenosphere size in reverse shoulder arthroplasty: is larger better for external rotation and abduction strength?

BACKGROUND

The role of glenosphere size in reverse shoulder arthroplasty (RSA) may be important in prosthetic stability, joint kinematics, rotator cuff tension and excursion, scapular impingement, humeral lateralization, deltoid wrap, and the occurrence of "notching." This study compared short- and midterm clinical and radiographic outcomes for 2 different glenosphere sizes of a single RSA type with respect to implant positioning, glenoid size, and morphology.

METHODS

This retrospective analysis included 68 RSA procedures that were prospectively documented in a local register during a 5-year postoperative period. Two glenosphere diameter sizes of 36 mm (n = 33) and 44 mm (n = 35) were used. Standard radiographs were made preoperatively (ie, baseline) and at 6, 12, 24, and 60 months after surgery. Range of motion, strength, the Constant-Murley score, and the Shoulder Pain and Disability Index were also assessed at all follow-up visits. The effect of glenosphere size on measured outcomes was adjusted for baseline values, patient gender, and humeral head diameter.

RESULTS

No significant differences were found in the functional scores between treatment groups at all follow-up assessments. At the 12-month follow-up, patients with a 44-mm glenosphere had greater external rotation in adduction (mean difference, 12°; P = .001) and abduction strength (mean difference, 1.4 kg; P = .026) compared with those with the smaller implant. These differences remained at 60 months. Scapular notching was observed in 38% of all patients, without any relevant difference between the groups.

CONCLUSION

An increase in glenosphere diameter leads to a clinically moderate but significant increase in external rotation in adduction and abduction strength at midterm follow-up.

Neer Award 2017: wear rates of 32-mm and 40-mm glenospheres in a reverse total shoulder arthroplasty wear simulation model

BACKGROUND

Larger glenosphere diameters have been used recently to increase prosthesis stability and impingement-free range of motion in reverse total shoulder arthroplasty. The goal of this study was to evaluate the rate of polyethylene wear for 32-mm and 40-mm glenospheres.

METHODS

Glenospheres (32 mm and 40 mm, n = 6/group) and conventional polyethylene humeral liners underwent a 5-million cycle (MC) wear simulation protocol. Abduction-adduction and flexion-extension motion profiles were alternated every 250,000 cycles. At each interval, mass loss was determined and converted to volume loss and wear rate. At 0, 2.5 MC, and 5 MC, liners were imaged using micro-computed tomography to determine surface deviation. White light interferometry was performed on liners and glenospheres at 0 and 5 MC to quantify surface roughness. Wear particle morphology was characterized by environmental scanning electron microscopy.

RESULTS

Total volume loss was significantly higher in 40-mm liners from 1.5 MC onward (P < .05). Overall, volumetric wear rate was significantly higher in 40-mm liners compared with 32-mm glenospheres (81.7 ± 23.9 mm³/MC vs. 68.0 ± 18.9 mm³/MC; P < .001). However, micro-computed tomography surface deviation results demonstrated increased linear penetration on 32-mm glenospheres compared with 40-mm glenospheres (0.36 ± 0.03 µm vs. 0.28 ± 0.01 µm; P = .002). Surface roughness measurements showed no difference for liners; however, increased roughness was noted for 40-mm glenospheres at 5 MC compared with 32 mm (P < .05).

CONCLUSION

Larger glenospheres underwent significantly greater polyethylene volume loss and volumetric wear rates, whereas smaller glenospheres underwent greater polyethylene surface deviations. The enhanced stability provided by larger glenospheres must be weighed against the potential for increased polyethylene wear.

Influence of glenosphere size on the development of scapular notching: a prospective randomized study

HYPOTHESIS

The objective of the study was to evaluate the development of scapular notching in reverse shoulder arthroplasty by comparing larger glenospheres (42 mm) with smaller glenospheres (38 mm).

METHODS

This was a prospective randomized study of 81 patients who had undergone reverse shoulder arthroplasty with a 2-year follow-up. Patients were randomized to receive either a 42-mm glenosphere (38 patients) or a 38-mm glenosphere (43 patients). Scapular notching development was assessed with an anteroposterior radiograph at the end of the follow-up. Functional outcome was assessed with the Constant score before surgery and at the end of follow-up. An independent blinded observer carried out radiologic and clinical assessments.

RESULTS

Scapular notching was present in 48.8% of the patients receiving a 38-mm glenosphere and in 12.1% of the patients receiving one of 42 mm, with significant differences between both (P < .001). No significant differences were noted between the 2 glenosphere size groups in terms of the total Constant score. Patients with a 42-mm glenosphere had a mean glenoid-glenosphere overhang of 6.1 mm, whereas patients with a 38-mm glenosphere had one of 4.2 mm, with significant differences between them (P < .001). No significant differences in the total Constant score were found between the patients whether they had scapular notching or not.

CONCLUSION

Bigger glenospheres (42 mm) significantly reduce development of scapular notching compared with smaller glenospheres (38 mm). Glenosphere size has no significant influence on functional outcomes measured with the Constant score.