Abstract
Background
In patients with reverse shoulder arthroplasty (RSA), the relationship between the patient’s body size and implant size is important for postoperative shoulder function. Asian patients, who have a short stature, could find the conventional RSA implant too big and tight. This study aimed to evaluate the clinical and radiological outcomes after RSA in Asian patients using a new implant designed to fit the body size of Asian patients. We also aimed to compare these outcomes with those who received a conventional implant.
Methods
This prospective study enrolled 120 patients who underwent RSA for a symptomatic irreparable massive rotator cuff tear, cuff tear arthropathy, or primary osteoarthritis with a full-thickness rotator cuff tear. Patients were randomly allocated 2:1 to receive an Asian-type RSA implant (group I) or conventional RSA implant (group II). All patients underwent plain radiography to evaluate acromiohumeral distance, acromion-deltoid tuberosity distance, lateral humeral offset, and center of rotation distance. Postoperative 1-year computed tomography (CT) scans were obtained for all patients to evaluate the position of peg screws and baseplates and the presence of scapular notching. Clinical outcomes were evaluated using American Shoulder Elbow Surgeons (ASES) score, Constant score, and active range of motion.
Results
Finally, 112 patients (80 in group I and 32 in group II) were included in this study. The mean patient age was 74.0 ± 5.5 years, and the mean patient height was 154.6 ± 8.1 cm. At the last visit, clinical scores and active range of motion significantly improved in both groups; however, the improvements did not differ significantly between the 2 groups. On the postoperative 1-year CT scan, the glenoid baseplate was more anteriorly placed in group II than in group I. The supero-inferior position of the glenoid baseplate did not significantly differ between the 2 groups. Other radiological parameters obtained through plain radiography showed no significant differences between the 2 groups. No differences were found in scapular notching (p = 0.999) and acromial stress fracture (p = 0.872) between the 2 groups.
Conclusions
Asian-type RSA implants showed comparable clinical and radiological outcomes with conventional RSA implants. Asian-type RSA implants allowed more accurate positioning of the glenoid baseplate, although that did not translate into superior clinical and radiological outcomes.
Keywords: Shoulder, Arthroplasty, Asian, Body size, Implant
In patients with reverse shoulder arthroplasty (RSA), the relationship between the patient’s body size and implant size crucially influences postoperative shoulder function and pain.1,2,3) A match between the patient’s body size and implant size ensures optimal soft-tissue tension, especially in the deltoid muscle, after surgery. This tension affects the degree of deltoid wrapping or lengthening. It is essential to increase deltoid muscle tension to enhance shoulder motion after RSA. However, too much tension could cause postoperative shoulder pain or stress fracture in the long term.1,4)
Various RSA implants with different designs and sizes are available these days.5,6) Both of the implant design and size could influence the deltoid muscle tension after RSA. Generally, Asians have a shorter stature than Caucasians, and this can lead to a size mismatch if an Asian patient receives the same size of the implant during RSA as a Caucasian patient.1,7,8) Three-dimensional computed tomography (3D-CT) evidence suggests that the normal Japanese glenoid bone is significantly smaller than the French glenoid bone in both width and height.8) Asian patients could find the conventional RSA implant too big and tight, which could lead to postoperative pain, poor longevity due to high stress on the glenoid implant, or acromial stress fracture.3) To avoid these complications arising from the size mismatch between the patient’s body and the RSA implant, it is necessary to use a better anatomically matched implant for small patients such as Asians.
This study was conducted to evaluate the clinical and radiological outcomes after RSA in Asian patients who received a new RSA implant designed to fit their body size. The outcomes in these patients were also compared with the outcomes in patients who received the conventional RSA implant. We hypothesized that patients who underwent RSA using the new implan would have better clinical and radiological outcomes than patients using the conventional implant.
METHODS
The Institutional Review Board of Ewha Womans University approved this study (IRB No. SEUMC 2020-11-023), and all participants provided informed consent.
The present study prospectively evaluated patients who underwent RSA between February 2021 and February 2022 at 4 ertiary referral university hospitals. The surgical indications for RSA were symptomatic shoulder disorders combined with rotator cuff deficiency that failed to receive the appropriate period of conservative treatment. The patients included in this study had a symptomatic irreparable massive rotator cuff tear, cuff tear arthropathy (CTA), or primary osteoarthritis (OA) of the glenohumeral joint with a full-thickness rotator cuff tear. All patients had undergone RSA and 3D-CT at postoperative 1 year. They were followed up for at least 2 years after surgery. The exclusion criteria were as follows: diagnosis of sequelae of septic shoulder, shoulder fracture, revision arthroplasty, and other arthritis such as rheumatoid arthritis or traumatic OA. Patients were randomly allocated 2 : 1 to receive an Asian-type RSA implant (group I; Coralis reverse shoulder system, Corentec) or the conventional RSA implant (group II; Comprehensive reverse shoulder system, Zimmer Biomet).
Clinical Evaluations
Clinical assessment using shoulder functional outcomes and physical examination were performed preoperatively and postoperatively at 3, 6, and 12 months and at the last visit. Restoration of shoulder function was evaluated using the American Shoulder Elbow Surgeons (ASES) score, Constant score, and visual analog scale (VAS) for pain score. The active range of motion (ROM) was checked at each visit. Active forward flexion and external rotation (ER) with the affected arm at the side were measured using a goniometer. Active internal rotation (IR) behind the back was measured at the most cephalad vertebral level reached by the tip of the extended thumb. The IR levels were converted into numerical data such as 0 for sacral level, 1 to 5 for L5 to L1, and 6 to 12 for T12 to T6, respectively. The presence of pseudoparalysis was also checked preoperatively and at each visit. Preoperative parameters were assessed by 4 physician assistants with an average of 5 years of orthopedic experience who were not involved in this study (JYP, SML, KSJ, and JEJ).
Radiological Evaluations
All patients underwent plain radiography including anteroposterior (AP), axial, and Grashey views preoperatively and postoperatively at 3, 6, and 12 months and the last visit. Acromiohumeral distance, acromion-deltoid tuberosity distance, lateral humeral offset, and center of rotation distance were measured on the AP view preoperatively and postoperatively at the last visit using previously described methods.9) The preoperative scapular neck angle and the postoperative prosthesis-scapular neck angle were assessed on the Grashey view.10) Postoperative scapular notching was graded using the Sirveaux classification system.11)
The 3D-CT image was obtained for all patients preoperatively to detect the degree of glenoid bone wear and at the postoperative 1 year to evaluate the position of the peg screw and baseplate. Distances between the center of the peg screw and the anterior, posterior, and inferior rims of the glenoid bone were measured on the axial and sagittal views of 3D-CT. On the sagittal view of 3D-CT, the distance between the inferior screw and the inferior rim of the glenoid bone and the glenosphere inferior overhang distance were also measured. The glenoid inferior overhang was evaluated by the distance between the glenosphere inferior margin and the inferior scapular neck (Fig. 1). Four surgeons with 7–8 years of orthopedic experience in each hospital (MSK, HGK, JWP, and SHC) independently assessed these measurements.
Fig. 1. Computed tomography (CT) measurements for glenoid implant. (A) Distances between the center of the peg screw and the anterior (a) and posterior (b) rims of the glenoid bone were measured on the axial view of CT scan. (B) Distance between the center of the peg screw and inferior (c) rim of the glenoid bone was also measured on the sagittal view of CT scan. (C) On the sagittal view of CT scan, the distance between the inferior screw and the inferior rim of the glenoid bone (d) was measured. (D) The glenoid inferior overhang (e) was calculated by the distance between the glenosphere inferior margin and the inferior scapular neck.
Surgical Treatment
All surgeons at each hospital shared the same surgical indications and standardized the operating environment and techniques. All operative settings including the patient’s position and surgical approach for RSA were carried out according to previously described methods.10) After tenotomy of the subscapularis on the lesser tuberosity, the shoulder was dislocated. After humeral head resection and soft-tissue preparation around the glenoid bone, the glenoid baseplate was placed along the inferior margin of the glenoid bone by palpation. In group I, a 26-mm glenoid baseplate was fixated with a 10° inferior tilt using 4 locking screws. A 36-mm standard glenosphere with a 4.0-mm inferior glenoid offset was used in group I. In group II, a 25-mm glenoid baseplate was inserted with a 10° inferior tilt with 2 compression screws in the superior and inferior holes and 2 locking screws in the anterior and posterior holes. A 2.5-mm inferior glenoid offset was applied, and a 36-mm standard glenosphere was used. Both the Asian-type and conventional RSA implants have a medialized glenoid and lateralized humerus implant design and a similar size of the glenoid baseplate. However, the conventional RSA implant has 3 mm more offset between the glenosphere and baseplate and has a 1-mm thicker central post of the baseplate than the Asian-type implant (Fig. 2). In all patients, the humeral stem was inserted with a 20° retroversion. The subscapularis tendon was sutured using the transosseous technique during the last stage of the procedure when the subscapularis tendon was amenable to repair. All operation procedures were performed similarly by 4 orthopedic surgeons at each hospital (JHO, JCY, YSK, and SJS).
Fig. 2. Lateral offset of the glenoid implant. (A) An offset between the glenosphere and baseplate (red arrow) was calculated as 4 mm in the Asian-type reverse shoulder arthroplasty (RSA) implant. (B) Conventional RSA implant showed 3 mm more offset compared with the Asian-type RSA implant.
After surgery, patients were immobilized with an abduction brace for 4 weeks. Progressive passive and active ROM exercises were started at 4 weeks, and shoulder muscle strengthening exercises were initiated at 12 weeks postoperatively. Return to physical activities began at 6 months postoperatively. All patients were treated using the same rehabilitation protocol.
Statistical Analysis
The Student t-test and chi-squared test were used to compare the clinical outcomes and radiologic parameters between the 2 groups. The paired t-test was performed to compare preoperative and postoperative clinical outcomes. The randomization table was prepared using the fixed randomization method. Statistical analyses were conducted using SPSS version 21.0 (IBM Corp.). A p < 0.05 was considered to indicate statistical significance.
Power analysis was performed using Web-R software (version 4.3.1). Using the previously calculated minimal clinically important difference in the ASES score for patients who underwent RSA, we determined that a sample size of 32 patients per group was necessary to achieve a power of 85% at an alpha of 5%.12) Considering a 20% follow-up loss, 40 patients were needed in each group. Because of a lack of data regarding Asian-type RSA implants, we decided to evaluate double the number of patients with Asian-type RSA implants than those with conventional RSA implants. Finally, this study enrolled 120 patients, 80 for Asian-type RSA implants and 40 for conventional RSA implants.
RESULTS
Patient Selection
The study enrolled 120 patients; however, 8 patients were excluded because of missing postoperative 3D-CT data. Finally, 112 patients (80 in group I and 32 in group II) were included in this study, and there were 31 male and 81 female patients. The mean patient age was 74.0 ± 5.5 years, and the mean patient height was 154.6 ± 8.1 cm (range, 139–174 cm). Preoperatively, 58 patients had CTA, 36 had irreparable rotator cuff tear, and 18 had OA with reparable rotator cuff tear. There were no significant differences in preoperative demographic data between the 2 groups. Detailed demographic data are described in Table 1.
Table 1. Demographic Characteristics of the Study Population.
| Characteristic | Group I (n = 80) | Group II (n = 32) | p-value | |
|---|---|---|---|---|
| Age (yr) | 74.0 ± 5.4 | 74.1 ± 5.9 | 0.957 | |
| Sex | 0.689 | |||
| Male | 23 | 8 | ||
| Female | 57 | 24 | ||
| Dominant arm involvement | 73 (91.2) | 29 (90.6) | 0.917 | |
| Height (cm) | 154.4 ± 7.9 | 155.1 ± 8.6 | 0.646 | |
| Body weight (kg) | 61.5 ± 9.8 | 62.3 ± 9.8 | 0.681 | |
| BMI (kg/m2) | 25.8 ± 3.4 | 25.9 ± 3.4 | 0.922 | |
| BMD | –1.9 ± 1.1 | –2.0 ± 1.3 | 0.467 | |
| Preoperative diagnosis | 0.077 | |||
| Irreparable rotator cuff tear | 26 (32.5) | 10 (31.3) | ||
| Cuff tear arthropathy | 45 (56.3) | 13 (40.6) | ||
| Osteoarthritis with rotator cuff tear | 9 (11.2) | 9 (28.1) | ||
| History of rotator cuff repair surgery | 14 (17.5) | 5 (15.6) | 0.811 | |
Values are presented as mean ± standard deviation or number (%). Group I: patients with Asian-type RSA implant, Group II: patients with conventional RSA implant.
BMI: body mass index, BMD: bone mineral density, RSA: reverse shoulder arthroplasty.
Clinical Evaluations
Clinical outcomes significantly improved after surgery in groups I and II (ASES score: p < 0.001, Constant score: p < 0.001, and VAS for pain score: p < 0.001). There were no significant differences in clinical scores between the 2 groups preoperatively and postoperative 1 year (Table 2). Preoperatively, 22 patients (19.6%) had pseudoparalysis (14 in group I and 8 in group II, p = 0.367), and psedoparalysis improved in all patients after surgery. Active forward flexion significantly improved postoperatively in both groups (active forward flexion: p = 0.001 in group I and p = 0.007 in group II), whereas active external and IR did not significantly improve after surgery (active ER: p = 0.106 in group I and p = 0.395 in group II; active IR: 0.183 in group I and 0.430 in group II).
Table 2. Comparison of Clinical Outcomes According to Prosthesis.
| Characteristic | Group I (n = 80) | Group II (n = 32) | p-value | |
|---|---|---|---|---|
| ASES score | ||||
| Preoperative | 42.5 ± 17.0 | 38.5 ± 20.1 | 0.299 | |
| At the last visit | 74.1 ± 11.6 | 73.5 ± 13.4 | 0.838 | |
| p-value | < 0.001* | < 0.001* | ||
| Constant score | ||||
| Preoperative | 50.6 ± 17.8 | 48.7 ± 18.6 | 0.605 | |
| At the last visit | 67.6 ± 13.2 | 65.3 ± 13.4 | 0.409 | |
| p-value | < 0.001* | < 0.001* | ||
| VAS for pain | ||||
| Preoperative | 5.2 ± 2.3 | 5.9 ± 3.0 | 0.169 | |
| At the last visit | 2.2 ± 1.5 | 2.0 ± 1.9 | 0.511 | |
| p-value | < 0.001* | < 0.001* | ||
| Active forward flexion | ||||
| Preoperative | 118.0 ± 43.5 | 114.1 ± 40.4 | 0.660 | |
| At the last visit | 134.5 ± 18.6 | 134.5 ± 17.8 | 0.994 | |
| p-value | 0.001* | 0.007* | ||
| Active external rotation | ||||
| Preoperative | 45.0 ± 22.4 | 47.7 ± 24.2 | 0.580 | |
| At the last visit | 50.1 ± 24.4 | 51.7 ± 19.6 | 0.742 | |
| p-value | 0.106 | 0.395 | ||
| Active internal rotation | ||||
| Preoperative | 5.3 ± 3.4 | 5.5 ± 3.2 | 0.750 | |
| At the last visit | 4.6 ± 3.3 | 4.9 ± 3.3 | 0.738 | |
| p-value | 0.183 | 0.430 | ||
Values are presented as mean ± standard deviation. Group I: patients with Asian-type RSA implant, Group II: patients with conventional RSA implant.
ASES: American Shoulder Elbow Surgeons, VAS: visual analog scale, RSA: reverse shoulder arthroplasty.
*Significant difference with p < 0.05.
Radiological Evaluations
On the postoperative 1-year CT scan, the glenoid baseplate was more anteriorly placed in group II than in group I (Table 3). There was no significant difference in the superoinferior position of the glenoid baseplate. Other radiological parameters obtained from plain radiography showed no significant differences between the 2 groups (Table 3). Scapular notching occurred in 21 patients (18.8%), and the number of patients with scapular notching in the 2 groups was not significantly different (Table 4).
Table 3. Comparison of Radiological Outcomes According to Prosthesis.
| Characteristic | Group I (n = 80) | Group II (n = 32) | p-value | |
|---|---|---|---|---|
| Acromiohumeral distance (mm) | ||||
| Preoperative | 6.9 ± 4.0 | 6.4 ± 3.5 | 0.548 | |
| At the last visit | 27.6 ± 7.9 | 28.7 ± 7.0 | 0.476 | |
| Acromion-deltoid tuberosity distance (mm) | ||||
| Preoperative | 141.6 ± 11.8 | 142.8 ± 10.7 | 0.607 | |
| At the last visit | 155.8 ± 14.7 | 149.3 ± 21.4 | 0.068 | |
| Lateral humeral offset (mm) | ||||
| Preoperative | 13.6 ± 6.0 | 11.8 ± 7.7 | 0.185 | |
| At the last visit | 16.5 ± 6.6 | 16.0 ± 7.9 | 0.700 | |
| Center of rotation distance (mm) | ||||
| Preoperative | 24.6 ± 2.9 | 24.2 ± 3.1 | 0.478 | |
| At the last visit | 46.7 ± 6.4 | 45.7 ± 6.2 | 0.448 | |
| Position of glenoid implant (mm) | ||||
| Peg-glenoid anterior rim distance | 17.3 ± 2.1 | 16.3 ± 2.3 | 0.028* | |
| Peg-glenoid posterior rim distance | 17.4 ± 1.8 | 18.5 ± 2.1 | 0.008* | |
| Peg-glenoid inferior rim distance | 21.8 ± 3.8 | 22.1 ± 4.0 | 0.643 | |
| Inferior screw-glenoid rim distance | 10.6 ± 3.4 | 10.5 ± 3.7 | 0.941 | |
| Glenosphere inferior overhanging | 5.8 ± 2.9 | 6.5 ± 2.5 | 0.202 | |
Values are presented as mean ± standard deviation. Group I: patients with Asian-type RSA implant, Group II: patients with conventional RSA implant.
RSA: reverse shoulder arthroplasty.
*Significant difference with p < 0.05.
Table 4. Scapular Notching Grade at the Final Follow-up.
| Characteristic | Group I (n = 80) | Group II (n = 32) | p-value | |
|---|---|---|---|---|
| Scapular notching, no. (%) | 15 (18.8) | 6 (18.8) | 0.999 | |
| Stage 0 | 65 | 26 | ||
| Stage 1 | 15 | 6 | ||
| Stage 2–4 | 0 | 0 | ||
Group I: patients with Asian-type RSA implant, Group II: patients with conventional RSA implant.
RSA: reverse shoulder arthroplasty.
Complications
During the surgery, 1 patient in group II had a humerus diaphysis fracture around the humeral stem during humeral stem insertion. Postoperatively, 1 patient in group I developed a brachial plexus injury temporarily that improved with conservative treatment. Four patients (3 in group I and 1 in group II) suffered from acromial stress fracture; however, there was no significant difference between the 2 groups (p = 0.872). All patients who had acromial stress fracture were treated conservatively. There was no other postoperative complications such as periprosthetic fracture or infection.
DISCUSSION
The present study showed that the use of Asian-type RSA implants resulted in clinical and radiological outcomes comparable with conventional RSA implants. The Asian-type RSA implants allowed more accurate positioning of the glenoid baseplate in the Korean population, although this did not influence the clinical and radiological outcomes. The relationship between the patient’s body size and implant size is important for achieving satisfactory clinical outcomes after RSA. A match between the 2 ensures optimal deltoid muscle tension, which will result in appropriate shoulder function for active movement. Excessive deltoid muscle tension due to body and implant size mismatch can cause several complications.1,2) Individual variations in body size and sizes of implants offered by various companies provide surgeons with a broad range of choices from which they can use the proper size of the implant according to the patient’s body size. However, an average Asian patient has a smaller body size than the average Caucasian or American; therefore, even the smallest conventional RSA implant may be overstepping or too tight for Asian patients.8,13) In a study comparing the bony structure of French and Japanese patients, Mizuno et al.8) reported that the Japanese glenoid size was 25.5 mm wide and 33.3 mm high, making it significantly smaller than the French glenoid by 1 to 2 mm. Moreover, the glenoid size is smaller in Asian women.13,14) The body and implant size mismatch that occurs when using conventional RSA implants in Asian patients can create a number of complications.3,15) To overcome this mismatch, Asian-type RSA implants have been developed considering the body size of Asian patients. The Asian-type implant used in this study has a medialized glenoid and lateralized humerus implant design with a 26-mm glenoid baseplate, which provides 24.6 mm of contact area to the glenoid surface. The conventional RSA implant, which was used in the present study, also has a medialized glenoid and lateralized humerus implant design and provides a 28-mm standard baseplate and 25-mm low profile baseplate. However, the conventional RSA implant has 3 mm more offset between the glenosphere and the baseplate than the Asian-type implant, which relatively increases the lateralization effect of the glenoid implant. Although the lateralization effect of the glenoid implant could positively influence the deltoid wrapping, this different implant design could affect the body and implant size relationship after surgery, especially in small patients. Moreover, the Asian-type RSA implant has a 1-mm smaller diameter of the central post of the glenoid baseplate than the conventional implant, making it better fit into the small-sized glenoid of Asian patients. This study has significant clinical relevance because it is the first study to compare the Asian-type RSA implant with the conventional RSA implant in Asian patients.
The body and implant size mismatch, especially when the implant size is relatively large for the patient, can result in excessive tension in the deltoid muscle and peri-articular soft tissue, which increases the risk of intraor postoperative peri-prosthetic fracture.16,17,18,19) Acromial stress fractures due to postoperative stress accumulation are more common in patients with higher postoperative lateralization shoulder angle and increased soft-tissue tension.20) In addition, excessive tension in the peri-articular soft tissue after implantation would make joint reduction difficult during surgery, which could finally lead to periprosthetic fracture intraoperatively. In the present study, a periprosthetic fracture occurred in 1 patient during surgery using the conventional RSA implant. Although periprosthetic fracture can occur due to several causes, soft-tissue tightness arising due to the body and implant size mismatch could be a reason for the intraoperative periprosthetic fracture. There was no difference in the incidence of postoperative acromial stress fractures between the 2 groups during the study periord. However, since the number of patients was small and patients were followed up only for 2 years postoperatively, longer-term follow-up data are needed to evaluate postoperative stress fracture.
The body and implant size relationship could also affect the degree of postoperative pain. In general, the degree of postoperative pain is proportional to the deltoid muscle tension or tightness due to the RSA implant.21,22) However, in the present study, there was no difference in postoperative pain severity between patients with the Asian-type and conventional RSA implants. The lack of a significant difference could be because of various factors involved in postoperative pain.23) In this study, there were no significant differences in clinical outcomes between the 2 groups at the 2-year follow-up. Although longer-term follow-up data are needed to determine the longevity of the implant, the results of this study suggest that the Asian-type RSA implant achieves clinical results comparable with the conventional implant.
In this study, the position of the baseplate was significantly different between the 2 groups. On the postoperative CT scan, the position of the baseplate peg screw was more centered in the glenoid cavity in the group that received the Asian-type RSA implant than in the group that received the conventional RSA implant. This could mean that the Asian-type RSA implant improved the accessibility of the instrument during intraoperative peg screw drilling than the conventional RSA implant. With the conventional RSA implant, the peg screw of the baseplate was positioned about 1 mm anterior to the glenoid center, which could be because the peg screw guiding instrument was not positioned far enough posteriorly. The cutting level of the proximal humerus could have also resulted in the anterior location of the peg screw guiding instrument; however, in this study, the humeral head was cut at the same level for all patients, and the neck-shaft angle was the same for both types of implants. Therefore, the accessibility of the peg screw guiding instrument might have contributed to this result. Although the difference in baseplate position between the 2 groups in the present study did not lead to a difference in clinical outcomes, it is possible that the cumulative effect of the difference in the baseplate position could influence the clinical outcomes in the long term. Further long-term follow-up studies are needed to confirm this possibility.
This study had several limitations. First, the follow-up period was relatively short. Future studies with a longer-term follow-up are needed to obtain more significant outcomes; however, the findings are meaningful because in this study the position of the implant was identified by performing a CT scan in all patients at postoperative 1 year. Second, stress fracture was evaluated based on CT scans and plain radiographs; however, single photon emission CT or a bone scan is more sensitive for detecting stress fracture after surgery.24,25) Third, this was a multicenter study in which 4 different surgeons performed the surgical procedures, resulting in a bias. To overcome this limitation, we tried to standardize the operation environment, technique, and rehabilitation protocol.
Asian-type RSA implants showed comparable clinical and radiological outcomes with conventional RSA implants. Asian-type RSA implants allowed more accurate positioning of the glenoid baseplate, although that did not translate into superior clinical and radiological outcomes.
ACKNOWLEDGEMENTS
This work was supported by a Korea Medical Device Development Fund grant funded by the Korean government (Ministry of Science and ICT, Ministry of Trade, Industry and Energy, Ministry of Health & Welfare, Ministry of Food and Drug Safety) (Project no. RS-2020-KD000301, 1711138974).
We appreciate Joo Young Paik, RN (Department of Orthopedic Surgery, Ewha Womans University Seoul Hospital), Sang Min Lee, RN (Department of Orthopaedic Surgery, Samsung Medical Center), Kyung Soon Jung, RN (Department of Orthopaedic Surgery, Seoul National University Bundang Hospital), and Ji Eun Jung, RN (Department of Orthopedic Surgery, Seoul St. Mary’s Hospital) for clinical parameter assessment. We also appreciate Min-Su Kim, MD (Department of Orthopedic Surgery, Ewha Womans University Seoul Hospital), Hyun Gon Kim, MD (Department of Orthopaedic Surgery, Samsung Medical Center), Jae Woo Park, MD (Department of Orthopaedic Surgery, Seoul National University Bundang Hospital), and Sung-Hyun Cho, MD (Department of Orthopedic Surgery, Seoul St. Mary’s Hospital) for radiologic parameter assessment.
Footnotes
CONFLICT OF INTEREST: Sang-Jin Shin is an editorial board member of the journal but was not involved in the peer reviewer selection, evaluation, or decision process of this article. No other potential conflicts of interest relevant to this article were reported.
References
- 1.Cho CH, Kim DH, Kim YJ, Kim SG. Complications after reverse total shoulder arthroplasty in the Korean population: a single center study of 299 cases. J Shoulder Elbow Surg. 2025;34(5):e280–e286. doi: 10.1016/j.jse.2024.08.014. [DOI] [PubMed] [Google Scholar]
- 2.Hirakawa Y, Manaka T, Ito Y, et al. Comparison of short-term clinical outcomes and radiographic changes in Grammont reverse shoulder arthroplasty between the French and Japanese populations: a propensity score-matched analysis. J Orthop Sci. 2024;29(1):128–132. doi: 10.1016/j.jos.2022.11.008. [DOI] [PubMed] [Google Scholar]
- 3.Ji JH, Jeong JY, Song HS, et al. Early clinical results of reverse total shoulder arthroplasty in the Korean population. J Shoulder Elbow Surg. 2013;22(8):1102–1107. doi: 10.1016/j.jse.2012.07.019. [DOI] [PubMed] [Google Scholar]
- 4.Schenk P, Sutter N, Molina E, Wieser K, Gerber C, Bachmann E. High delta angle after reverse total shoulder arthroplasty increases stresses of the acromion: biomechanical study of different implant positions. J Shoulder Elbow Surg. 2024;33(12):2718–2724. doi: 10.1016/j.jse.2024.05.034. [DOI] [PubMed] [Google Scholar]
- 5.Hole RM, Fenstad AM, Gjertsen JE, Hallan G, Furnes ON. 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. Acta Orthop. 2024;95:463–471. doi: 10.2340/17453674.2024.41344. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Shah AA, Sheth M, McKee M, Lederman E. Evolution of reverse shoulder arthroplasty design rationales and where we are now. J Am Acad Orthop Surg. 2025;33(2):e61–e71. doi: 10.5435/JAAOS-D-23-01265. [DOI] [PubMed] [Google Scholar]
- 7.Matsumura N, Oki S, Ogawa K, et al. Three-dimensional anthropometric analysis of the glenohumeral joint in a normal Japanese population. J Shoulder Elbow Surg. 2016;25(3):493–501. doi: 10.1016/j.jse.2015.08.003. [DOI] [PubMed] [Google Scholar]
- 8.Mizuno N, Nonaka S, Ozaki R, Yoshida M, Yoneda M, Walch G. Three-dimensional assessment of the normal Japanese glenoid and comparison with the normal French glenoid. Orthop Traumatol Surg Res. 2017;103(8):1271–1275. doi: 10.1016/j.otsr.2017.08.015. [DOI] [PubMed] [Google Scholar]
- 9.Lee JH, Chun YM, Kim DS, Lee DH, Shin SJ. Early restoration of shoulder function in patients with the Grammont prosthesis compared to lateralized humeral design in reverse shoulder arthroplasty. J Shoulder Elbow Surg. 2021;30(11):2533–2542. doi: 10.1016/j.jse.2021.03.145. [DOI] [PubMed] [Google Scholar]
- 10.Kim MS, Rhee YG, Oh JH, Yoo JC, Noh KC, Shin SJ. Clinical and radiologic outcomes of small glenoid baseplate in reverse total shoulder arthroplasty: a prospective multicenter study. Clin Orthop Surg. 2022;14(1):119–127. doi: 10.4055/cios20301. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Sirveaux F, Favard L, Oudet D, Huquet D, Walch G, Mole D. Grammont inverted total shoulder arthroplasty in the treatment of glenohumeral osteoarthritis with massive rupture of the cuff: results of a multicentre study of 80 shoulders. J Bone Joint Surg Br. 2004;86(3):388–395. doi: 10.1302/0301-620x.86b3.14024. [DOI] [PubMed] [Google Scholar]
- 12.Werner BC, Chang B, Nguyen JT, Dines DM, Gulotta LV. What change in American Shoulder and Elbow Surgeons score represents a clinically important change after shoulder arthroplasty? Clin Orthop Relat Res. 2016;474(12):2672–2681. doi: 10.1007/s11999-016-4968-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Cabezas AF, Krebes K, Hussey MM, et al. Morphologic Variability of the Shoulder between the Populations of North American and East Asian. Clin Orthop Surg. 2016;8(3):280–287. doi: 10.4055/cios.2016.8.3.280. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Matsuki K, Sugaya H, Hoshika S, et al. Three-dimensional measurement of glenoid dimensions and orientations. J Orthop Sci. 2019;24(4):624–630. doi: 10.1016/j.jos.2018.11.019. [DOI] [PubMed] [Google Scholar]
- 15.Tashiro E, Takeuchi N, Kozono N, Nabeshima A, Teshima E, Nakashima Y. Risk of penetration of the baseplate peg in reverse total shoulder arthroplasty for an Asian population. Int Orthop. 2022;46(5):1063–1071. doi: 10.1007/s00264-022-05328-x. [DOI] [PubMed] [Google Scholar]
- 16.Haislup BD, Ashmyan R, Johnston PS, Wright MA, Abbasi P, Murthi AM. Effect of glenosphere lateralization with and without coracoacromial ligament transection on acromial and scapular spine strain in reverse shoulder arthroplasty. JSES Int. 2022;6(6):884–888. doi: 10.1016/j.jseint.2022.08.010. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Shah SS, Gentile J, Chen X, et al. Influence of implant design and parasagittal acromial morphology on acromial and scapular spine strain after reverse total shoulder arthroplasty: a cadaveric and computer-based biomechanical analysis. J Shoulder Elbow Surg. 2020;29(11):2395–2405. doi: 10.1016/j.jse.2020.04.004. [DOI] [PubMed] [Google Scholar]
- 18.Wong MT, Langohr GD, Athwal GS, Johnson JA. Implant positioning in reverse shoulder arthroplasty has an impact on acromial stresses. J Shoulder Elbow Surg. 2016;25(11):1889–1895. doi: 10.1016/j.jse.2016.04.011. [DOI] [PubMed] [Google Scholar]
- 19.Haase L, Ina J, Harlow E, Chen R, Gillespie R, Calcei J. The influence of component design and positioning on soft-tissue tensioning and complications in reverse total shoulder arthroplasty: a review. JBJS Rev. 2024;12(4):e23.00238. doi: 10.2106/JBJS.RVW.23.00238. [DOI] [PubMed] [Google Scholar]
- 20.Kriechling P, Weber F, Karczewski D, Borbas P, Wieser K. Predictive factors of acromial fractures following reverse total shoulder arthroplasty: a subgroup analysis of 860 shoulders. JSES Int. 2023;7(5):812–818. doi: 10.1016/j.jseint.2023.04.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Hao KA, Cueto RJ, Gharby C, et al. Influence of lateralized versus medialized reverse shoulder arthroplasty design on external and internal rotation: a systematic review and meta-analysis. Clin Shoulder Elb. 2024;27(1):59–71. doi: 10.5397/cise.2023.00577. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Oh JH, Jeong HJ, Won YS. Implant selection for successful reverse total shoulder arthroplasty. Clin Shoulder Elb. 2023;26(1):93–106. doi: 10.5397/cise.2022.01193. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Waheed I, Ediripolage F, Alvi I, Haider JM. Preoperative risk factors for pain after reverse total shoulder arthroplasty: a systematic review. Cureus. 2024;16(5):e60041. doi: 10.7759/cureus.60041. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Cho CH, Kim DH, Won KS. Potential utility of SPECT/CT for early detection of scapular stress reaction following reverse total shoulder arthroplasty. Clin Nucl Med. 2025;50(1):66–69. doi: 10.1097/RLU.0000000000005438. [DOI] [PubMed] [Google Scholar]
- 25.Park JH, Kim HG, Kim JS, Kim SC, Yoo JC. SPECT/CT for early detection of stress reactions after reverse shoulder arthroplasty: potential clinical significance. Clin Nucl Med. 2024;49(3):246–249. doi: 10.1097/RLU.0000000000005019. [DOI] [PubMed] [Google Scholar]