Reconsidering the clinical outcomes of the stemless reverse total shoulder arthroplasty design implant
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This paper focuses on the radiographic and clinical outcomes of stemless reverse total shoulder arthroplasty (RTSA) after a minimum follow-up of 2 years [1]. The final findings include significant improvements of patient outcome including forward flexion and internal rotation; no significant change was observed in external rotation. Clinical scores, such as visual analog scale score, Korean Shoulder Scoring system, and American Shoulder and Elbow Surgeons, also showed notable improvement. Not all RTSA implants are the same. The clinical outcomes of stemless RTSA have been increasingly studied in Europe, with several studies demonstrating its effectiveness and benefits [2-4]. In this study, 50 patients using stemless RTSA with Lima SMR glenoid and 61 humeral component (Lima Corporate) were enrolled. The current paper describes the first case series of stemless RTSA using the Lima system in Korea with a minimum of 2 years of follow-up.
In a systemic review of stemless RTSA, stemless these implants had lower humeral complication rates compared with traditional stemmed systems. The stemless implants also offer advantages in preserving bone stock and reducing complications and revisions, making them a viable option for select patients [4]. Stemless RTSA is not yet widely adopted in Korea. However, the current study concluded that the procedure demonstrates favorable short-term outcomes (in a minimum 2 years of follow-up). Longer-term studies are needed to further validate these findings. We also observed a low complication rate and good early clinical outcomes, indicating that this approach can be considered for broader use in the future.
In this study, conventional complications like subluxation, dislocation, infection, periprosthetic fracture, osteolysis, or loosening of the stemless humeral component (SHC) were not observed. Radiographically, minor radiolucent lines (<2 mm) were noted, but no cases of osteolysis or humeral component loosening were reported. Humeral component failure occurred in one case (not described in this paper), where the SHC was dislodged one week after surgery, requiring revision surgery with a stemmed component. In this study, Bone mineral density (BMD) was measured preoperatively, and attention was paid to the bone quality of the proximal humeral metaphysis. Even if osteoporosis was not observed in the spine or hip, the results suggested that BMD evaluation of the proximal humerus is necessary before performing stemless RTSA.
This study is the first case series of stemless RTSA using an inlay design in Korea. These stemless design features a 135° neck-shaft angle and 20° retroversion. The most notable complication in this study was scapular notching, observed in 18 of 50 cases (36%). Scapular notching was grade 1 in 15 cases and grade 2 in 3 cases, with no occurrences of the more severe grade 3 or 4. In conventional RTSA, scapular notching is the most common complication, and the incidence varies widely, ranging from 4.6% to 96% [5]. In the systemic review by Kostretzis et al. [4], scapular notching was reported in 15.2% of cases, and lucencies around humeral component were reported in 0.8% of shoulders. Recent studies evaluating the effects of implant design and position report notching rates as low as 10%–30%, indicating that these two factors play important roles in scapular notching [6-8]. While stemless RTSA implants differ from conventional implants, stemless design used in this study did not present any humeral component issues.
Mechanical engagement of the humeral cup with the scapular neck has been related to bone loss, polyethylene wear, osteolysis, and glenoid implant loosening and failure, all of which can negatively impact clinical outcomes. Careful observation for scapular notching is essential following RTSA. When notching is diagnosed, grading the lesion helps assess its severity and guide treatment. Radiographic evaluation, including Grashey anteroposterior, lateral, and axillary views, is important for accurate grading. The system by Sirveaux et al. [9] classifies notching from grade 1 (affecting the pillar) to grade 4 (involving the central post). Grades 1 and 2 result from mechanical impingement or erosion, while grades 3 and 4 are more likely due to a biological response to particles. In the current study, grade 1 and 2 notching occurred, and we speculate that scapular notching is a result of improper components due to limited glenoid exposure caused by high neck cutting. Notably, higher grade (grade 3 or 4) notching is often associated with longer follow-up periods. Therefore, a longer-term follow up evaluation of scapular notching for stemless RTSA is necessary.
Compared with conventional stemmed RTSA, stemless RTSA offers several advantages, including preservation of humeral bone stock (important for future revision surgery), reduced risk of periprosthetic fractures, increased flexibility in reconstruction, simplified revision surgeries, and avoidance of stress shielding. However, stemless RTSA also presents challenges, such as dependence on bone quality, difficulties in glenoid exposure, and risk of component loosening. These disadvantages underscore the importance of proper patient selection and surgical expertise for successful outcomes. Despite these challenges, the advantages of stemless RTSA contribute to its growing popularity, particularly in patients with good bone quality. Further research with a longer follow-up is needed to determine the optimal treatment strategies for stemless RTSA especially in the Korean population.
Notes
Author contributions
Conceptualization: JHJ. Data curation: BSK. Formal analysis: BSK. Methodology: BSK. Validation: BSK, JHJ. Writing – original draft: BSK. Writing – review & editing: BSK, JHJ.
Conflict of interest
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Data availability
Contact the corresponding author for data availability.
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