Stemless Prosthesis for Total Shoulder Arthroplasty

Stemless Reverse Shoulder Arthroplasty

Since the Food and Drug Administration (FDA) approval nearly two decades ago, the indications for and utilization of reverse shoulder arthroplasty (RSA) have expanded considerably. Stemless RSA designs have been used in Europe since 2005, but have only recently been introduced in domestic Investigational Device Exemption trials. Potential advantages of stemless RSA are similar to those of stemless anatomic total shoulder arthroplasty, which may include fewer shaft-related complications, avoidance of stress shielding, bone preservation, and easier revision surgery. European data support similar outcomes between certain stemless RSA prostheses compared with that of stemmed RSA implants at early and mid-term follow-up. However, long-term outcomes remain to be seen and differences exist between the stemless RSA designs used in Europe and those being studied in domestic clinical trials. An understanding of the potential advantages and disadvantages of stemless RSA, differences between existing designs, and reported clinical outcomes is prudent for the safe and meaningful implementation of this new technology in the United States.

Stemless components lead to improved radiographic restoration of humeral head anatomy compared with short-stemmed components in total shoulder arthroplasty

BACKGROUND

Restoring the native center of rotation (COR) in total shoulder arthroplasty (TSA) has been shown to improve postsurgical function, subjective outcomes, and implant longevity. The primary purpose of this study was to compare postoperative radiographic restoration of the humeral COR between short-stem and stemless humeral implants by evaluating the mean COR shift between the 2 techniques. Secondary outcomes evaluated were comparisons of COR shift outliers, humeral head implant thickness and diameter, direction of COR shift, and neck-shaft angle (NSA).

METHODS

This study was a multicenter retrospective comparative study using a consecutive series of primary anatomic TSA patients who received either a short-stem or stemless humeral implant. Radiographically, COR and NSA were measured by 2 fellowship-trained surgeons using the best-fit circle technique on immediate postoperative Grashey radiographs.

RESULTS

A total of 229 patients formed the final cohort for analysis that included 89 short stems and 140 stemless components. The mean COR shift for short stems was 2.7 mm (±1.4 mm) compared with 2.1 mm (±0.9 mm) for stemless implants (P < .001). The percentage of short-stem implant patients with a >2 mm COR difference from native was 66.0% (n = 62) compared with 47.4% (n = 64) for stemless (P = .006). The percentage of short-stem patients with a >4 mm COR difference from native was 17.0% (n = 16) compared with 3.0% (n = 4) for stemless (P < .001). The mean humeral implant head thickness for short stems was 18.7 ± 2.2 mm compared with 17.2 ± 1.3 mm for stemless implants (P < .001). The mean humeral head diameter for short stems was 48.7 ± 4.4 mm compared with 45.5 ± 3.5 mm for stemless implants (P < .001). The NSA for the short-stem cohort was 136.7° (±3.6°) compared with 133.5° (±6.0°) for stemless (P < .001).

CONCLUSIONS

Stemless prostheses placed during TSA achieved improved restoration of humeral head COR and were less likely to have significant COR outliers compared with short-stem implants.

Medium-term results of stemless, short, and conventional stem humeral components in anatomic total shoulder arthroplasty: a New Zealand Joint Registry study

BACKGROUND

The purpose of this study was to compare the medium-term results for anatomic total shoulder arthroplasty by humeral component stem length. We hypothesize that the newer stemless implants may have comparable results to short-stem and conventional stemmed implants.

METHODS

The 12 most used anatomic total shoulder arthroplasty implants on the New Zealand Joint Registry were included in the study. Implants were categorized by stem length-conventional, short, and stemless. The primary outcome was revision up to 7 years postsurgery. Secondary outcomes included revision cause, implant survival, and early functional outcomes as evaluated by the Oxford Shoulder Score. Analysis was stratified by age and surgeon volume to control for potential confounding.

RESULTS

A total of 3952 patients (conventional, 3114; short, 360; stemless, 478) were included in the study. No significant difference in revision rate per 100 component-years was found between stemless, short-stem, and conventional stemmed implants (revision rate per 100 component-years: conventional, 1.01 [95% confidence interval (CI) 0.89-1.14]; short, 0.54 [95% CI 0.25-1.03]; stemless, 0.99 [95% CI 0.51-1.74]). This finding was irrespective of patient age or surgeon volume. There were no cases of humeral loosening up to 7 years' follow-up and no cases of intraoperative humeral fracture in the stemless group. Functional outcomes at 6 months postsurgery suggested better outcomes in the stemless group compared with the conventional stem group (mean Oxford Shoulder Score: conventional, 39.4; stemless, 40.7; P value = .023).

CONCLUSION

The medium-term survival of stemless implants for anatomic total shoulder arthroplasty appears comparable to short-stem and conventional stemmed implants. Further follow-up is required to understand the long-term survivorship and functional outcomes between these groups.

A Comparison of Operative Time and Intraoperative Blood Volume Loss Between Stemless and Short‐stem Anatomic Total Shoulder Arthroplasty: A Single Institution's Experience

There has been increasing interest in the use of stemless humeral implants for total shoulder arthroplasty when compared with both short-stem (SS) and standard-length implants. Although evidence for decreased surgical time and blood loss exists for stemless versus standard-length stems, far less literature exists comparing these clinical parameters for stemless versus SS implants.

Lesser Tuberosity Osteotomy Does Not Appear to Compromise Fixation or Function Compared With Peel in Short-Stem Anatomic Shoulder Arthroplasty

Several methods are available for subscapularis management in total shoulder arthroplasty (TSA). The goal of this study was to compare radiographic and clinical outcomes of short-stem TSA stratified by subscapularis management technique. A multicenter trial was completed evaluating primary short-stem TSA performed with a subscapularis peel (n=80) or lesser tuberosity osteotomy (LTO) (n=59). The primary outcome measure was subscapularis function, as measured by internal rotation and strength at 1 year postoperatively. Secondary outcomes included patient-reported outcomes, radiographic changes, and implant loosening. Patients in the peel group obtained better active internal rotation by spinal level (P=.004). No difference was seen between groups for internal rotation with 90° shoulder abduction (P=.862) or belly press (P=.903). Statistically significant improvements in functional outcomes were seen without clinical differences. Radiographic changes showed no difference in stem shift, subsidence, or at-risk loosening rate. Anterior subluxation of the humerus was observed among 2% of the LTO group vs 17% of the peel group (P=.006). At short-term follow-up, those in the peel group appear to have a better final spinal level of internal rotation, whereas those in the LTO group have a significantly lower rate of anterior humeral subluxation. Both LTO and subscapularis peel appear safe for short-stem TSA, with no radiographic evidence of loosening. [Orthopedics. 2022;45(3):151-155.].

A biomechanical comparison of subscapularis tenotomy repair techniques for stemless shoulder arthroplasty

BACKGROUND

One of the leading challenges for surgeons shifting to stemless anatomic total shoulder arthroplasty (TSA) is subscapularis repair. In the available literature reporting outcomes after stemless TSA, subscapularis tenotomy with side-to-side repair is the most common technique despite some concerns regarding this technique in the biomechanical and clinical literature. Accordingly, this study investigated subscapularis tenotomy repair with stemless TSA with 2 primary objectives: (1) to evaluate the subscapularis tendon dimensions with reference to subscapularis tenotomy to determine the amount of tendon remaining for side-to-side repair after shoulder arthroplasty and (2) to biomechanically compare 2 methods of subscapularis tenotomy repair after stemless TSA-side-to-side repair and anchor-based repair.

METHODS

We used 12 male shoulder specimens for this study. To address our first objective, measurements were made to calculate the dimensions of the subscapularis tendon at the superior, middle, and inferior levels to determine the amount of tendon remaining after tenotomy. These specimens were then divided into 2 groups (n = 6 in each group) to biomechanically compare subscapularis tenotomy repair with (1) traditional side-to-side repair and (2) anchor-based repair. The shoulders then underwent biomechanical testing with primary outcomes including load to failure and cyclic displacement.

RESULTS

The mean subscapularis tendon width measured from the medial insertion at the lesser tuberosity to the muscle-tendon junction varied depending on the level: 19.5 mm superiorly (95% confidence interval [CI], 16.2-22.8 mm); 18.3 mm at the midportion (95% CI, 13.6-23.0 mm); and 13.1 mm inferiorly (95% CI, 9.1-17.1 mm). With a tenotomy made 1 cm medial to the lesser tuberosity insertion, a mean of 3.1 mm of tendon remained medially at the inferior subscapularis, with one-third of specimens having no tendon left medially at this level. On comparison of tenotomy repair techniques, the anchor-based technique had a 57% higher ultimate load to failure compared with the side-to-side repair (448 N vs. 249 N, P < .001). There were no significant differences in cyclic displacement (6.1 mm vs. 7.1 mm, P = .751) and construct stiffness (38.1 N/mm vs. 42.9 N/mm, P = .461) between techniques.

CONCLUSIONS

With traditional techniques for subscapularis tenotomy for anatomic TSA, there is very little tendon remaining inferiorly for side-to-side repair. When subscapularis tenotomy is performed for stemless TSA, a double-row anchor-based repair has a better time-zero ultimate load to failure compared with side-to-side repair.

Mid-term outcomes of a stemless ceramic head anatomic total shoulder replacement

Background

In an anatomic shoulder replacement (aTSR) good results have been reported with the use of a stemless humeral prosthesis. In vitro a ceramic articulation with polyethylene has been shown to produce less polyethylene wear particles than with metal. This study aims to evaluate clinical and radiographic results of a stemless aTSR with a ceramic head articulating with a polyethylene glenoid component, with mid-term follow-up.

Methods

All patients (n = 92) in this prospective study had an aTSR utilizing a stemless humeral component with a ceramic head and a cemented double pegged cemented polyethylene glenoid component for glenohumeral osteoarthritis. Pre- and postoperative clinical evaluations at 2 years were performed using the ASES score, Constant score, SPADI score, DASH score, VAS pain score, patient satisfaction and range of motion. There was a 5-year evaluation of SPADI, ASES, pain, and satisfaction, plus radiographic assessment of glenoid component radiolucent lines and humeral osteolysis.

Results

Seventy-four cases (68.1 ± 7.1 years) had a five-year follow-up and demonstrated active elevation improvement from 91.3° preoperatively to 151.1° (p < 0.001). Further improvement was identified with the ASES from 41.6 to 94.3, the SPADI from 62.9 to 4.3, VAS pain from 5.6 to 0.4 (0–10), and satisfaction levels were at 96%. Sixty-two cases had no glenoid radiolucent lines with a maximum Lazarus score of 2 in one patient. Constant scores, available up to 2 years, improved significantly from 30.3 to 77.9 (p < 0.001). There was one case that required revision for glenoid loosening.

Conclusions

Overall, the 5-year results of this ceramic head prosthesis demonstrated good radiographic and clinical outcomes.

Trial registration

ACTRN12613001183774. Registered: 29 October 2013 - Retrospectively registered.

Australian New Zealand Clinical Trials Registry (ANZCTR).

Subscapularis management in stemmed and stemless total shoulder arthroplasty: a surgeon decision-making analysis study

Background

Stemless total shoulder arthroplasty (TSA) continues to grow in popularity as an evolution of stemmed humeral implants. Proposed advantages include bone preservation and ease of potential revision. However, absence of a stem may necessitate a change in subscapularis takedown approach. Specifically, there is theoretical concern about violation of supportive bone with lesser tuberosity osteotomy when using a stemless device. Therefore, the goal of this study was to identify if surgeons change their subscapularis takedown preference when performing stemless vs. stemmed TSA.

Methods and materials

Data from a consecutive series of patients who underwent stemmed and stemless TSA at an academic institution were collected. The subscapularis management technique was documented. Subscapularis takedown techniques were divided into 2 groups: soft-tissue approach (subscapularis tenotomy or peel) and bony approach (lesser tuberosity osteotomy). Historical preference for each surgeon was determined by evaluating techniques employed using stemmed TSA. A Cramers V analysis was run to determine the strength of association between this historical preference and subscapularis management technique used for stemless TSA.

Results

One hundred and fifty-four patients were included in this analysis. There were 72 and 82 stemmed and stemless arthroplasty cases performed, respectively. Of the 154 patients, 50.6% were women. The average age of patients was 64.2 years. Four surgeons were included in this study. In all, there were 79 and 75 bony and soft-tissue subscapularis techniques, respectively. The historical preference for 3 of the surgeons was a subscapularis bony approach, and the historical preference for one of the surgeons was a soft-tissue approach. A Cramer's V analysis was used to measure the relative strength of association between patient factors, historical subscapularis management preference, and subscapularis takedown approach in stemless TSA. Our analysis yielded a value of 0.65 (P < .01), indicating a redundant association between subscapularis management approach used between stemmed and stemless implant per surgeon.

Conclusion

In determining subscapularis tendon management strategy, in surgeons who performed stemmed TSA before stemless TSA, the subscapularis takedown approach used for stemless TSA is strongly associated with surgeon's historical preference for stemmed TSA. Future research will be needed to determine the clinical ramifications of this finding.

Biomechanical evaluation of 2 techniques of repair after subscapularis peel for stemless shoulder arthroplasty

BACKGROUND

Stemless anatomic total shoulder arthroplasty (TSA) has been gaining significant popularity but poses unique challenges for subscapularis repair. Tenotomy with side-to-side repair has been the most frequently reported technique for subscapularis repair with stemless TSA but has the poorest biomechanical properties, and clinical failures have been reported. There is limited biomechanical evidence evaluating other subscapularis repair techniques for stemless TSA. Therefore, the goal of this study was to investigate 2 additional techniques using a subscapularis peel for subscapularis repair with a stemless TSA.

METHODS

We used 18 male cadaveric specimens to investigate the native subscapularis (n = 6) and 2 subscapularis repair techniques (n = 12) after stemless anatomic TSA (Eclipse). A subscapularis peel with double-row, knotless anchor-based repair (n = 6) was compared with a subscapularis peel with a "backpack" repair (n = 6). The specimens then underwent biomechanical testing, including cyclic displacement and load-to-failure testing. The mode of failure was also recorded.

RESULTS

The native tendon had the highest ultimate load to failure (mean, 1017.1 N). Load to failure was similar between the 2 study groups: 397.9 N for the peel and backpack repair and 593.7 N for the knotless anchor-based repair (P > .05 for all comparisons). Moreover, no significant differences in cyclic displacement or construct stiffness were found between the groups (P > .05 for all comparisons).

CONCLUSIONS

A double-row, knotless anchor-based repair of a subscapularis peel for stemless anatomic shoulder arthroplasty has similar biomechanical properties to a backpack repair technique; however, both techniques fail to reproduce the native biomechanical properties at time zero.

Assessing the Value to the Patient of New Technologies in Anatomic Total Shoulder Arthroplasty

BACKGROUND

Publications regarding anatomic total shoulder arthroplasty (TSA) have consistently reported that they provide significant improvement for patients with glenohumeral arthritis. New TSA technologies that have been introduced with the goal of further improving these outcomes include preoperative computed tomography (CT) scans, 3-dimensional preoperative planning, patient-specific instrumentation, stemless and short-stemmed humeral components, as well as metal-backed, hybrid, and augmented glenoid components. The benefit of these new technologies in terms of patient-reported outcomes is unknown.

METHODS

We reviewed 114 articles presenting preoperative and postoperative values for commonly used patient-reported metrics. The results were analyzed to determine whether patient outcomes have improved over the 20 years during which new technologies became available.

RESULTS

The analysis did not identify evidence that the results of TSA were statistically or clinically improved over the 2 decades of study or that any of the individual technologies were associated with significant improvement in patient outcomes.

CONCLUSIONS

Additional research is required to document the clinical value of these new technologies to patients with glenohumeral arthritis.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Stemless total shoulder arthroplasty in elderly patients with primary osteoarthritis of shoulder - a developing country experience

BACKGROUND

We evaluated the imaging and functional outcomes of anatomic stemless shoulder arthroplasty (ECLIPSE) in elderly patients with primary osteoarthritis of the glenohumeral joint in Asian developing countries.

METHODS

Thirty patients were treated using stemless TSA in 26 months period (years 2017 and 2019), and were followed for a minimum of 24 months. Functional outcomes were assessed using Constant and ASES scores. Radiolucent lines and osteopenia were analyzed on radiographs.

RESULTS

Pre-surgery Constant and ASES scores improved from 27.33(21-38) and 29.67(22-38) to 68(54-78) and 71(71.4(56-79) at final follow up. Around the humeral component, one patient had calcar thinning and a radiolucent line thicker than 2 mm, while six patients had radiolucent lines less than 2 mm. The mean glenoid radiolucency score was 2± 1.1.

CONCLUSION

In our setting, stemless total shoulder arthroplasty demonstrated significant improvement in functional scores at short- to mid-term follow-up. Radiographic findings did not correlate with functional scores.

3D-Analysis of the Proximal Humeral Anatomy Before and After Stemless Shoulder Arthroplasty-A Prospective Case Series Study

BACKGROUND

Stemless shoulder arthroplasty (SSA) is used to anatomically reconstruct proximal humerus geometry and preserve proximal humerus bone stock. The current literature lacks 3D-analysis of pre- and postoperative proximal humeral anatomy after SSA. The aim of this study was to prospectively analyze the humeral head anatomy using a computer-assisted topography mapping technique after SSA in relation to the preoperative status and the contralateral (not affected) side.

METHODS

Twenty-nine patients (mean age: 63.5 ± 11.7 years) affected by primary shoulder osteoarthritis and treated with SSA were included. Preoperative and postoperative CT scans of the affected and contralateral sites were analyzed regarding joint geometry. Clinical outcome was assessed by Constant and Disabilities of the Arm, Shoulder and Hand (DASH) score shortly before and one year after surgery.

RESULTS

Clinical outcome improved significantly. No correlation between clinical outcome and the evaluated anatomical parameters was found. There was a significant decrease of the humeral head height (p < 0.01) and radius (p = 0.03) in the preoperative versus the postoperative joint geometry. The comparison to the contralateral site showed also a significant decrease of the humeral head height (p < 0.01). All other parameters showed no significant differences.

CONCLUSION

Proximal humeral anatomy can be almost anatomically reconstructed by SSA. Solely the humeral head height differs significantly to the preoperative as well as contralateral morphology.

Radiographic humeral head restoration after total shoulder arthroplasty: does the stem make a difference?

BACKGROUND

Humeral stem designs for total shoulder arthroplasty have varied over the years, with a recent trend toward shorter stems. The purpose of this study was to examine the impact of humeral component stem length on the ability to restore the native humeral head anatomy.

METHODS

We performed a retrospective review including patients who underwent total shoulder arthroplasty for primary osteoarthritis between 2007 and 2017 with complete operative reports and adequate radiographs. Surgical data including stem design were collected. Preoperative and postoperative radiographic measurements of the center of rotation (COR), humeral head height (HH), and neck-shaft angle were performed. Restoration of the native humeral anatomy was deemed "acceptable" based on postoperative differences in the COR ≤ 3 mm, HH ≤ 5 mm, and neck-shaft angle > 130°. Deviations between preoperative and postoperative measurements were compared across stem types. All available 2-year stemless implant radiographs were also analyzed.

RESULTS

In total, 261 patients were included, with 31 stemless, 43 short-stem, and 187 standard-stem implants. There was no significant difference in COR restoration in the x-axis direction (P = .060) or y-axis direction (P = .579). There was no significant difference in restoration of acceptable HH by stem type (P = .339). Stemless arthroplasty implants were more likely to be placed in varus (22.6%) compared with short-stem (7.0%) and standard-stem (3.7%) designs (P < .001).

CONCLUSION

Restoration of humeral anatomic parameters occurred significantly less with stemless implants than with short- and standard-stem implants. The stem of a shoulder arthroplasty implant aids surgeons in accurately restoring patient-specific anatomy.

Eclipse stemless shoulder prosthesis vs. Univers II shoulder prosthesis: a multicenter, prospective randomized controlled trial

BACKGROUND

Total shoulder arthroplasty is an accepted treatment for glenohumeral osteoarthritis. The Arthrex Eclipse shoulder prosthesis is a stemless, canal-sparing humeral prosthesis with bone ingrowth capacity on the trunnion, as well as through the fenestrated hollow screw, that provides both diaphyseal and metaphyseal load sharing and fixation.

METHODS

Between 2013 and 2018, 16 sites in the United States enrolled 327 patients (Eclipse in 237 and Arthrex Univers II in 90). All patients had glenohumeral arthritis refractory to nonsurgical care. Strict exclusion criteria were applied to avoid confounding factors such as severe patient comorbidities, arthritis not consistent with osteoarthritis, and medical or prior surgical treatments that may have affected outcomes. Patients were randomized to the Eclipse or Univers II group via block randomization.

RESULTS

In total, 149 Eclipse and 76 Univers II patients reached 2-year follow-up (139 Eclipse patients [93.3%] and 68 Univers II patients [89.5%] had complete data). The success rate using the Composite Clinical Success score was 95% in the Eclipse group vs. 89.7% in the Univers II group. No patient exhibited radiographic evidence of substantial humeral radiolucency, humeral migration, or subsidence at any point. Reoperations were performed in 7 patients (3.2%) in the Eclipse group and 3 (3.8%) in the Univers II group.

CONCLUSION

The Arthrex Eclipse shoulder prosthesis is a safe and effective humeral implant for patients with glenohumeral arthritis at 2-year follow-up, with no differences in outcomes compared with the Univers II shoulder prosthesis.

Proximal humeral osteolysis and glenoid radiolucent lines in an anatomic shoulder arthroplasty: a comparison of a ceramic and a metal humeral head component

BACKGROUND

In vitro wear studies demonstrate decreased polyethylene wear with a ceramic compared with a metal humeral head. In this in vivo study, we analyzed prospectively collected 5-year data, comparing the outcomes of 2 types of humeral implants.

METHODS

Sixty-two anatomic total shoulder arthroplasties (TSAs) (59 patients) were performed using the same glenoid component and 2 types of modular humeral implants (metal-head long-stem prosthesis in group A vs. ceramic-head stemless prosthesis in group B). Radiographic analysis for proximal humeral osteolysis and glenoid component radiolucent lines was performed at an average of 5.5 years. Functional outcomes were prospectively evaluated according to the visual analog scale score for pain; satisfaction level; American Shoulder and Elbow Surgeons score; active elevation; Shoulder Pain and Disability Index score; and Disabilities of the Arm, Shoulder and Hand score.

RESULTS

There were 39 TSAs in group A (mean age, 68.1 years) and 23 TSAs in group B (mean age, 67 years). Clinical improvement was similar for both groups. Some proximal humeral osteolysis occurred in 56% of all TSAs. Group A showed increased osteolysis compared with group B (72% vs. 30%, P = .005). Glenoid radiolucent lines were far more frequent in group A, and group A showed a direct relationship between the extent of humeral osteolysis and the severity of glenoid radiolucent lines (P < .001).

CONCLUSION

The stemless ceramic-head replacements showed fewer glenoid radiolucent lines and less humeral osteolysis than the long-stem metal-head replacements. In the group with metal-head replacements, correlation was shown between glenoid radiolucent lines and humeral osteolysis.

Cementless metaphyseal reverse shoulder arthroplasty: our preliminary experience

Reverse shoulder arthroplasty (rTSA) is a largely used procedure with a wide variety of indications. The incidence of this surgery is increased in recent years and the literature expects similar trend for the future. Metaphyseal stem rTSA seems to be a promising solution considering major objectives the preservation of humeral bone stock and ease of revision. In our study we analyzed 19 patients treated with cementless metaphyseal stem rTSA for osteoarthritis (group A) and acute fractures (group B). In group A (7 patients) the average Constant score improved from 21,57 (16-29) to 56,85 (38-72), the average SST improved from 2,29 (1-4) to 9,43 (8-12) and the mean VAS score improved from 14,29 to 4,86. In group B (12 patients) the mean Constant-Murlay score at last follow up was 42,17; the average SST was 7 and average pain score was 8,92. Overall active range-of-motion (ROM) improved significantly. Surgical considerations, clinical (analyzing Constant score and Simple Shoulder Test) and radiological short-term outcomes are encouraging, with low rate of complications. Long term follow-up studies are necessary to confirm our findings and the potential benefits related to these implants. (www.actabiomedica.it)