Do Stemless Implants Have a Role in Anatomic TSA?
In a multicenter randomized controlled trial, researchers reported equivalent outcomes with the use of a stemless and a traditional stemmed humeral implant, both from the same manufacturer.
Timothy G. Reish, MD
Romeo AA, Erickson BJ, Costouros J, Long N, Klassen J, Araghi, A, Brown, J, Setter K, Port J, Tyndall W, Verma N, Sears B, Brandon T, Smith M, McFadden E, Patterson P, Stein J, Cohen B, Abboud J. Eclipse stemless shoulder prosthesis vs. Univers II shoulder prosthesis: a multicenter, prospective randomized controlled trial. J Shoulder Elbow Surgery. 2020 Nov 29(11): 2200-2212.
In this multicenter, prospective, randomized, controlled trial, Romeo et al evaluated 2-year outcomes with a traditional stemmed humeral prosthesis (Univers II) for anatomic total shoulder arthroplasty (TSA) versus a stemless humeral implant (Eclipse), both from the same manufacturer (Arthrex; Naples, Florida).
Between 2013 and 2018, researchers at 16 sites in the US enrolled 327 patients (237 stemless, 90 traditional) who were indicated for anatomic TSA for glenohumeral degenerative joint disease (DJD) unresponsive to conservative treatment. To avoid confounding variables, strict inclusion criteria were followed, such as age over 21 years, an intact or reparable rotator cuff, and DJD due to osteoarthritis, post-traumatic arthritis, avascular necrosis, or rheumatoid arthritis. Patients had to have adequate bone stock and a Constant score of less than 50.
Patients were excluded if they had glenoid bone deficiency precluding replacement, post-traumatic humeral deformity requiring stem fixation, or osteoporosis defined by a bone density T score of less than -2.5. The researchers also excluded patients with major comorbidities, psychiatric disorders, workers’ compensation claims, or ipsilateral shoulder surgery within the last 12 months prior to the planned arthroplasty.
After a thorough review, 296 patients were included in the study (218 stemless, 78 traditional). Patients were followed over a 2-year period at 3, 6, 12, and 24 months postoperatively. The subscapularis was managed by surgeon choice, but the postoperative rehabilitation protocol was standardized. This included use of a sling for 2 weeks, physical therapy focusing on passive range of motion (ROM) and protection of the subscapularis repair, and then progression of physical therapy to active and active-assisted ROM. Strengthening commenced once full ROM was achieved, with resisted internal rotation beginning no sooner than 3 months postoperatively.
Patients were evaluated by the Composite Clinical Success (CCS) score, which includes the Constant Score, radiographic analysis, complications, revision rate, and reoperations. Successful outcomes were defined as a Constant score improvement of more than 10 and absence of radiographic lucency, migration, or subsidence at 2-year follow-up. In addition, any evidence of implant failure, periprosthetic fracture, reoperation, or implant removal was deemed an unsuccessful outcome.
At the end of 2 years, 149 patients (93.5%) in the stemless group and 68 patients (89.5%) in the traditional group were available for analysis. The CCS score was 95% for the stemless group and 89.7% for the traditional group. No patient in either group had any evidence of radiographic complications.
Reoperations were performed in 7 patients (3.2%) in the stemless group and 3 (3.8%) patients in the standard group. These numbers are from the entire cohort, not just the patients who had completed the 2-year follow-up. Reoperations were done for infection or traumatic/attritional rotator cuff rupture. No intraoperative fractures were observed in the stemless group, while there were 2 intraoperative fractures in the standard group.
The authors concluded that the stemless humeral prosthesis was safe and effective in patients with glenohumeral DJD and that its use provided outcomes similar to those of the traditional stemmed humeral implant for anatomic TSA.
Anatomic TSA is becoming increasingly common in the US as a consequence of the rising incidence of glenohumeral DJD, particularly in younger patient populations. The growing number of younger patients undergoing anatomic TSA is expected to lead to an increased incidence of revision surgery, creating problems for surgeons and potentially compromising patient outcomes.
Eliminating complicating factors inherent in revision surgery is paramount to optimizing outcomes. The study by Romeo et al provides evidence to support the use of a stemless humeral implant in anatomic TSA by showing that clinical and radiographic outcomes are equivalent to those of a traditional stemmed humeral implant. Furthermore, the study’s findings suggest that the complication rate is equal to, if not superior to, that of stemmed humeral prostheses.
Stemless humeral implants overcome many of the problems with traditional stemmed implants:
- Preservation of humeral bone stock, which eliminates the need for osteotomy and the potential for bone loss on the humeral side in the revision setting
- Implant placement irrespective of the constraints of the humeral canal, allowing the surgeon to more easily match the patient’s native version and inclination angle, which is especially significant when faced with post-traumatic deformity
- Reduction in intraoperative blood loss, surgical time, and, potentially, postoperative pain by eliminating the need to broach and violate the humeral canal
- Reduction in the risk of intraoperative fracture, as verified by this study: 2 intraoperative fractures in the traditional group versus 0 intraoperative fractures in the stemless group
Stress shielding can be a significant problem with traditional stemmed humeral implants that gain distal fixation, leading to problems with proximal humeral reconstruction in the revision setting. The study by Romeo et al showed no evidence of radiographic problems associated with the stemless humeral implant at 2-year follow-up.
This study suggests that the stemless humeral implant is a safe and effective alternative to the traditional stemmed humeral prosthesis and that in the appropriate patient, the stemless implant may replace the need for a stemmed device.
Timothy G. Reish, MD, is a Clinical Assistant Professor, Division of Sports Medicine, Department of Orthopaedic Surgery, NYU Langone Medical Center – Hospital for Joint Diseases, New York, New York.
Disclosures: Dr. Reish has disclosed that he is a paid presenter/speaker for Arthrex, Inc.