Background. Stemless prostheses are recognized to be an effective solution for anatomic total shoulder arthroplasty (TSA) while providing bone preservation and shortest operating time. Reverse shoulder arthroplasty (RSA) with stemless has not showed the same effectiveness, as clinical and biomechanical performances strongly depend on the design. The main concern is related to stability and bone response due to the changed biomechanical conditions; few studies have analyzed these effects in anatomic designs through Finite Element Analysis (FEA), however there is currently no study analyzing the reverse configuration. Additionally, most of the studies do not consider the effect of changing the neck-shaft angle (NSA) resection of the humerus nor the proper assignment of spatial bone properties to the bone models used in the simulations. The aim of this FEA study is to analyze bone response and primary stability of the SMR Stemless prosthesis in reverse with two different NSA cuts and two different reverse angled liners, in bone models with properties assigned using a quantitative computed tomography (QCT) methodology. Methods. Sixteen fresh-frozen cadaveric humeri were modelled using the QCT-based finite element methodology. The humeri were CT-scanned with a hydroxyapatite phantom to allow spatial bone properties assignment [Fig. 1]. Two implanted SMR stemless reverse configurations were considered for each humerus: a 150°-NSA cut with a 0° liner and a 135°-NSA cut with a 7° sloped liner [Fig. 2]. A 105° abduction loading condition was simulated on both the implanted reverse models and the intact (anatomic) humerus; load components were derived from previous dynamic biomechanical simulations on RSA implants for the implanted stemless models and from the OrthoLoad database for the intact humeri. The postoperative bone volume expected to resorb or remodel [Fig. 3a] in the implanted humeri were compared with their intact models in sixteen metaphyseal regions of interest (four 5-mm thick layers parallel to the resection and four anatomical quadrants) by means of a three-way repeated measures ANOVA followed by post hoc tests with Bonferroni correction. In order to evaluate primary stability, micromotions at the bone-Trabecular Titanium interface [Fig. 3b] were compared between the two configurations using a Wilcoxon matched-pairs signed-rank test. The significance level α was set to 0.05. Results. With the exception of the most proximal layer (0.0 – 5.0 mm), the 150°-NSA configuration showed overall a statistically significant lower bone volume expected to resorb (p = 0.011). In terms of bone remodelling, the 150°-NSA configuration had again a better response, but fewer statistically significant differences were found. Regarding micromotions, there was a median decrease (Mdn = 3.2 μm) for the 135°-NSA configuration (Mdn = 40.3 μm) with respect to the 150°-NSA configuration (Mdn = 43.5 μm) but this difference was non-significant (p = 0.464). Conclusions. For the analyzed SMR Stemless configurations, these results suggest a reduction in the risk of bone resorption when a 0° liner is implanted with the humerus cut at 150°. The used QCT-based methodology will allow further investigation, as this study was limited to one single design and load case. For any figures or tables, please contact the authors directly

Aims

The use and variety of stemless humeral components in anatomical total shoulder arthroplasty (TSA) have proliferated since their advent in 2004. Early outcomes are reassuring but independent mid-term results are scarce. This independent study reports a consecutive series of 143 Eclipse stemless shoulder prostheses with a minimum five-year (5 to 10) follow-up.

Aims. The purpose of this study was to compare clinical results, long-term survival, and complication rates of stemless shoulder prosthesis with stemmed anatomical shoulder prostheses for treatment of osteoarthritis and to analyze radiological bone changes around the implants during follow-up. Methods. A total of 161 patients treated with either a stemmed or a stemless shoulder arthroplasty for primary osteoarthritis of the shoulder were evaluated with a mean follow-up of 118 months (102 to 158). The Constant score (CS), the Disabilities of the Arm, Shoulder and Hand (DASH) score, and active range of motion (ROM) were recorded. Radiological analysis for bone adaptations was performed by plain radiographs. A Kaplan-Meier survivorship analysis was calculated and complications were noted. Results. The ROM (p < 0.001), CS (p < 0.001), and DASH score (p < 0.001) showed significant improvements after shoulder arthroplasty for both implants. There were no differences between the groups treated with stemmed or stemless shoulder prosthesis with respect to the mean CS (79.2 (35 to 118) vs 74.4 (31 to 99); p = 0.519) and DASH scores (11.4 (8 to 29) vs 13.2 (7 to 23); p = 0.210). The ten-year unadjusted cumulative survival rate was 95.3% for the stemmed anatomical shoulder prosthesis and 91.5% for the stemless shoulder prosthesis and did not differ between the treatment groups (p = 0.251). The radiological evaluation of the humeral components in both groups did not show loosening of the humeral implant. The main reason for revision for each type of arthroplasties were complications related to the glenoid. Conclusion. The use of anatomical stemless shoulder prosthesis yielded good and reliable results and did not differ from anatomical stemmed shoulder prosthesis over a mean period of ten years. The differences in periprosthetic humeral bone adaptations between both implants have no clinical impact during the follow-up. Cite this article: Bone Joint J 2021;103-B(7):1292–1300

In the past century several shoulder reconstruction systems with different types of prostheses and fixation methods have been developed to improve shoulder arthroplasty, especially to cover a wide range of pathologies and revision situations. The aim of this prospective trial was to report clinical and radiological mid-term results of a stemless humeral head replacement with metaphyseal hollow screw fixation. A consecutive series of 147 shoulders in 138 patients (84 female, 54 male; mean age of 67 years, range 40–84) undergoing stemless humeral head arthroplasty were considered for this single-centre trial. We prospectively followed 120 shoulders (40 hemi- and 80 total-arthroplasties) for an average of five years or until a reoperation. Patient's clinical and functional outcome was evaluated according to the Constant score and active range of motions (ROM) was measured. Patient's satisfaction with the treatment was evaluated. Additionally, operating times and complications were recorded. Radiological assessment for radiolucencies or implant migration was performed. The mean Constant score significantly increased from 35 points preoperatively to 62 points at the last follow-up (p<0.001). All subcomponents (pain, daily activity, ROM, strength) of the Constant score were significantly (p<0.001) higher at follow-up. Active flexion improved from 90° to 150° (p<0.001), active abduction from 78° to 120° (p<0.001), and active external rotation from 20° to 40° (p<0.001) between preoperative and last clinical assessment. Furthermore, 54% of the patients were very satisfied, 34% satisfied, and 12% unsatisfied. Operating times of the new stemless prosthesis were significantly shorter compared to a stemmed prosthesis. Over the follow-up period, all humeral head components were radiological centred, changing radiolucencies were detected; however no implant loosening occurred. Revision surgery for implant loosening only occurred in the metal-backed glenoid component with hollow screw fixation; otherwise no complication due to implant loosening was detected. The promising five-year results suggest that the concept of this stemless humeral head replacement might be an expedient alternative to existing shoulder replacements. Anatomical cutting of the humeral head and hollow screw fixation allow a familiar access to the glenoid combined with a shaft independent, less complex bone-sparing surgery along with shorter operating times and favourable revision situation

Introduction. The new era of shoulder arthroplasty is moving away from long stemmed, cemented humeral components to cementless, stemless and metaphyseal fixed implants and to humeral resurfacing. The early clinical results and functional outcome of stemless shoulder arthroplasty is presented. Methods. A retrospective single-surgeon series of stemless shoulder prostheses implanted from 2011 to 2013 at our institution was evaluated. Perioperative complications, Theatre time and length of hospital stay (LOS) were recorded. Postoperative radiographic and clinical evaluation including measurement of joint mobility, the Oxford Shoulder Score (OSS), and Disabilities of the Arm, Shoulder and Hand (DASH) score by independent evaluators were made. Results. A total of 23 stemless shoulder arthroplasty were implanted in 22 patients. Mean age was 57.8 years. Mean follow up was 22 months (8–45). Symptomatic primary gleno-humeral osteoarthritis was the main indication for implantation (83%). None of the patients experienced periprosthetic fractures, glenoid notching, and implant loosening/migration. Mean OSS (44 ± 6.0) and mean DASH score (11 ± 6.5). Mean operative time was (88 ± 16.0 min) and mean length of hospital stay (1.1 ± 0.82 day). Active shoulder motion improved by (mean): 30° (95% CI 10–45) external rotation, 67° (95% CI 30- 100) forward elevation and 54° (95% CI 35- 90) Abduction. Conclusion. The implantation of stemless shoulder prosthesis in our institution offered good clinical results manifested by improved range of motion and favourable patient reported outcome measures. Although long term follow up is warranted, early results appear promising in young patients with symptomatic gleno-humeral osteoarthritis

Aims

Stemless humeral implants have been developed to overcome stem-related complications in total shoulder arthroplasty (TSA). However, stemless implant designs may hypothetically result in less stable initial fixation, potentially affecting long-term survival. The aim of this study is to investigate early fixation and migration patterns of the stemless humeral component of the Simpliciti Shoulder System and to evaluate clinical outcomes.

Introduction: The Motus (Osteo) total knee replacement design is an uncemented, stemless, hydroxyapatite-coated prosthesis designed as a low profile resurfacing implant. Aim: To review the results after five to eight years of the use of this prosthesis by one surgeon and to discuss the perceived advantages of its design. Methods: Between 1992 and 1996 the Motus (Osteo) prosthesis was used in 606 primary total knee replacements in 409 patients. The evaluation was undertaken using a clinical knee score based on the Knee Society Score and the Hospital for Special Surgery (HSS) score, which produces a maximum score of 200/200. Results: The mean age was 69 years (range: 31 to 88 years) with 53% of the patients being female. Osteoarthritis was the underlying pathology in the majority of the cases. The minimum time to follow up was 60 months (mean: 79, range: 60 to 104 months). The mean pre-operative knee score was 98/200 with a range of movement from six degrees to 122 degrees. After five years, the mean knee score was 180/200 with a range of movement from one degree to 113 degrees. To date only two patients have required a revision procedure, both for deep infection. Twenty-six patients have died and six have been lost to follow-up as they are overseas. Conclusion: At a minimum five-year review, the Motus (Osteo) total knee replacement prosthesis produced excellent functional and clinical results with a low rate of complications

Summary Statement. The current biomecahnical study demonstrated that the stemless peripheral leg humeral component prototype and central screw humeral component prototype achieved similar initial fixation as stemmed Global Advantage humeral component in terms of resultant micromotion in total shoulder arthroplasty. Introduction. A stemless humeral component may offer a variety of advantages over its stemmed counterpart, e.g. easier implantation, preservation of humeral bone stock, fewer humeral complications, etc. However, the initial fixation of a stemless humeral component typically depends on cementless metaphyseal press-fit, which could pose some challenges to the initial stability. Long-term success of cementless implants is highly related to osseous integration, which is affected by initial implant-bone interface motion. 1. The purpose of the study was to biomechanically compare micromotion at the implant-bone interface of three humeral components in total shoulder arthroplasty. Patients & Methods. Three humeral components were evaluated: Global Advantage, a central screw prototype, and a peripheral leg prototype. All components were the smallest sizes available. Global Advantage is a stemmed design. Both central screw prototype and peripheral leg prototype are stemless designs. Five specimens were tested for each design. Composite analogue humeral models were utilized to simulate the humeral bone. The cortical wall had a thickness of 3 mm and a density of 481 kg/m. 3. , while the cancellous density was 80 kg/m. 3. The model was custom fabricated to accommodate 40 mm humeral component and had a 45° resected surface and a square base to facilitate test setup. Each humeral component was implanted per its surgical technique. The construct was clamped in a vise with the humeral shaft angled at 27°. A MTS test system was employed to conduct the test. A sinusoidal compressive load from 157 N to 1566 N (2BW) was applied to the humeral component at 1 Hz for 100 cycles. The implant-bone interface micromotion was measured with a digital image correlation system which had a resolution of less than 1 micron. The micromotion measurement was transformed to 2 components: 1 was parallel and the other perpendicular to the humeral resection surface. Peak-valley micromotion from the last 10 cycles were averaged and utilised for data analyses. A one-way ANOVA and post-hoc Tukey tests were performed to compare the micromotion of different designs (α=0.05). Results. Micromotion of Global Advantage parallel to the resection (X-Axis) was significantly less than that of central screw prototype and peripheral leg prototype. Micromotion of peripheral leg prototype perpendicular to the resection (Y-Axis) was significantly less than Global Advantage and central screw prototype. There was no significant difference between different designs in resultant micromotion. Discussion/Conclusion. Clinical studies have shown that current stemless shoulder prosthesis yielded encouraging results in mid-term follow-ups. Particularly, the stemless Arthrex Eclipse humeral component, a central screw design, has been reported to have a secure bony fixation and ingrowth at an average of 23 months postoperatively. 4. The current study demonstrated that the stemless peripheral leg prototype and central screw prototype achieved similar initial fixation as stemmed Global Advantage in terms of resultant micromotion, and provided biomechanical evidence that stemless humeral components could have comparable initial stability to stemmed counterparts

We prospectively reviewed 1000 consecutive patients who underwent a cementless, hydroxyapatite-coated, stemless, total knee replacement over a period of nine years. Regular post-operative clinical follow-up was performed using the Knee Society score. The mean pre-operative score was 96, improving to 182 and 180 at five and ten years, respectively. To date, there have been seven (0.5%) cases which required revision, primarily for septic loosening (four cases), with low rates of other post-operative complications. The cumulative survival at ten years with revision as the end-point, was 99.14% (95% confidence interval 92.5 to 99.8). These results support the use of hydroxyapatite in a cementless total knee replacement since it can give reliable fixation with an excellent clinical and functional outcome.

We carried out a prospective study of 118 hydroxyapatite-coated, cementless total knee replacements in patients who were ≤ 55 years of age and who had primary (92; 78%) or post-traumatic (26; 22%) osteoarthritis. The mean period of follow-up was 7.9 years (5 to 12.5). The Knee Society clinical scores improved from a pre-operative mean of 98 (0 to 137) to a mean of 185 (135 to 200) at five years, and 173 (137 to 200) at ten years. There were two revisions of the tibial component because of aseptic loosening, and one case of polyethylene wear requiring further surgery. There was no osteolysis or progressive radiological loosening of any other component. At 12 years, the overall rate of implant survival was 97.5% (excluding exchange of spacer) and 92.1% (including exchange of spacer).

Cementless total knee replacement can achieve excellent long-term results in young, active patients with osteoarthritis. In contrast to total hip replacement, polyethylene wear, osteolysis and loosening of the prosthesis were not major problems for these patients, although it is possible that this observation could change with longer periods of follow-up.