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Abstract Introduction In reverse shoulder arthroplasty (RSA) new designs enable greater amounts of lateralization to prevent instability and scapular notching and increase range of motion, however, excessive lateralization leads to stress upon the acromion that can result in scapular spine fatigue fractures. Aim of this study was to gender- and size-specifically assess the influence of glenosphere size and different humeral designs on lateralization, distalization, and bony impingement-free range of motion (ROM) in patients undergoing RSA. Methods Computed tomography scans from 30 osteoarthritic patients (f:15, m:15) and 20 cuff tear arthropathy patients (f:10, m:10) were used to virtually simulate RSA implantation. The efficacy of an inlay Grammont-type system vs. an onlay lateralizing system combined with different glenosphere sizes (36 mm vs. 42 mm) in achieving ROM, lateralization, and distalization was evaluated. Moreover, gender and patient’s constitution were correlated to humeral size by radiologically measuring the best-fit circle of the humeral head. Results A different amount of relative lateralization was achieved in both genders using large glenospheres and onlay designs. Latter yielded a higher ROM in all planes for men and women with a 42 mm glenosphere; with the 36 mm glenosphere, an increased ROM was observed only in men. The 155° inlay design led to joint medialization only in men, whereas all designs led to lateralization in women. When adjusting the absolute amount of lateralization to humerus’ size (or patient’s height), regardless of implant type, women received greater relative lateralization using 36 mm glenosphere (inlay: 1%; onlay 12%) than men with 42 mm glenosphere (inlay: -3%; onlay: 8%). Conclusion The relative lateralization achieved using onlay design is much higher in women than men. Small glenospheres yield greater relative lateralization in women compared to large glenospheres in men. Humeral lateralization using onlay designs should be used cautiously in women, as they lead to great relative lateralization increasing stress onto the acromion. Level of evidence Basic Science Study, Computer Modeling.

Introduction: In reverse shoulder arthroplasty (RSA) new designs enable greater amounts of lateralization to prevent instability and scapular notching and increase range of motion, however, excessive lateralization leads to stress upon the acromion that can result in scapular spine fatigue fractures. Aim of this study was to gender- and size-specifically assess the influence of glenosphere size and different humeral designs on lateralization, distalization, and bony impingement-free range of motion (ROM) in patients undergoing RSA. Methods: Computed tomography scans from 30 osteoarthritic patients (f:15, m:15) and 20 cuff tear arthropathy patients (f:10, m:10) were used to virtually simulate RSA implantation. The efficacy of an inlay Grammont-type system vs. an onlay lateralizing system combined with different glenosphere sizes (36 mm vs. 42 mm) in achieving ROM, lateralization, and distalization was evaluated. Moreover, gender and patient's constitution were correlated to humeral size by radiologically measuring the best-fit circle of the humeral head. Results: A different amount of relative lateralization was achieved in both genders using large glenospheres and onlay designs. Latter yielded a higher ROM in all planes for men and women with a 42 mm glenosphere; with the 36 mm glenosphere, an increased ROM was observed only in men. The 155° inlay design led to joint medialization only in men, whereas all designs led to lateralization in women. When adjusting the absolute amount of lateralization to humerus' size (or patient's height), regardless of implant type, women received greater relative lateralization using 36 mm glenosphere (inlay: 1%; onlay 12%) than men with 42 mm glenosphere (inlay: -3%; onlay: 8%). Conclusion: The relative lateralization achieved using onlay design is much higher in women than men. Small glenospheres yield greater relative lateralization in women compared to large glenospheres in men. Humeral lateralization using onlay designs should be used cautiously in women, as they lead to great relative lateralization increasing stress onto the acromion. Level of evidence: Basic Science Study, Computer Modeling. [ABSTRACT FROM AUTHOR]

Although cementation of humeral stems has long been considered the gold standard for anatomic shoulder arthroplasty (aTSA), cementless, or press-fit, fixation offers a relatively cheaper and less demanding alternative, particularly in the setting of a revision procedure. However, this approach has been accompanied by concerns of implant loosening and high rates of radiolucency. In the present study, we performed a propensity-matched comparison of clinical and patient-reported outcomes between cemented and cementless fixation techniques for aTSA. We hypothesized that cemented fixation of the humeral component would have significantly better implant survival while providing comparable functional outcomes at final follow-up. This study was a retrospective comparison of 50 shoulders undergoing aTSA: 25 using cemented humeral fixation vs. 25 using press-fit humeral fixation. Patients in the 2 groups were propensity matched according to age, sex, and preoperative American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score. Primary outcome measures included range of motion (ROM) (forward elevation, external rotation, internal rotation), patient-reported outcomes (ASES, Simple Shoulder Test [SST], visual analog scale [VAS]), and implant survival. At baseline, the 2 fixation groups were similar in regard to age, sex, body mass index, preoperative ASES score, and surgical indication. Mean follow-up was 11.7 ± 4.95 years in the cemented cohort and 9.13 ± 3.77 years in the press-fit cohort (P =.045). Both groups demonstrated significant improvements postoperatively in all included ROM and patient-reported outcomes. However, press-fit patients reported significantly better VAS, ASES, and SST scores. Mean VAS pain score was 1.1 ± 1.8 in press-fit patients and 3.2 ± 3.0 in cemented patients (P =.005). The mean ASES score was 87.7 ± 12.4 in press-fit patients and 69.5 ± 22.7 in cemented patients (P =.002). Lastly, the mean SST score was 9.8 ± 3.1 in press-fit patients and 7.7 ± 3.7 in cemented patients (P =.040). Both fixation techniques provided lasting implant survivorship with only a single revision operation in each of the cohorts. Herein, we provide a propensity-matched, long-term comparison of patients receiving anatomic shoulder arthroplasty stratified according to humeral stem fixation technique. The results of this analysis illustrate that both types of humeral fixation techniques yield durable and significant improvements in shoulder function with similar rates of survival at 10 years of follow-up. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to evaluate clinical and radiological outcomes of a short stem reverse shoulder prosthesis with metaphyseal fixation specifically in older patients. Methods: All patients, older than 70 years, submitted to a Reverse Shoulder Arthroplasty (RSA) using a cementless onlay short stem (Aequalis Ascend™ Flex Convertible Shoulder System (Stryker®)) from January 2017 to December 2021, with a minimum follow-up of 2 years, were included. Postoperative radiographs were assessed for stem loosening, subsidence, and varus-valgus tilt. Range of motion, visual analogue scale for pain, constant score, complication rate and revision rate were also analysed. Results: A total of 34 patients with a mean age of 75 years (range 71–83 years) were submitted to a cementless onlay short stem RSA with a Bone Increased Off-Set (BIO-RSA) construct. The mean follow-up period was 61 months (range 54–87). Significant improvements (p < 0.001) were observed for the constant score and range of motion from the preoperative state to final follow-up. One case exhibited a significant varus deviation (> 5˚) during the follow-up period. No case of stem loosening was identified. There was only one case of complication because of post-traumatic dislocation, but the stem didn't need revision. Conclusion: Short stem RSA, even in patients older than 70 years, can yield a stable fixation with a good clinical and radiological outcome at short-medium term follow-up. Level of Evidence: Level III; Retrospective Study [ABSTRACT FROM AUTHOR]

The use of uncemented humeral stems in total shoulder arthroplasty (TSA) is known to be associated with stress shielding. This may be decreased with smaller stems that are well-aligned and do not fill the intramedullary canal; however, the effect of humeral head positioning and incomplete head backside contact has not yet been investigated. The purpose of this study was to quantify the effect of changes in humeral head position and incomplete head backside contact on bone stresses and expected bone response following reconstruction. Three-dimensional finite element models of 8 cadaveric humeri were generated, which were then virtually reconstructed with a short-stem implant. An optimally sized humeral head was then positioned in both a superolateral and inferomedial position for each specimen that was in full contact with the humeral resection plane. Additionally, for the inferomedial position, 2 incomplete humeral head backside contact conditions were simulated whereby contact was defined between only the superior or inferior half of the backside of the humeral head and the resection plane. Trabecular properties were assigned based on computed tomography attenuation and cortical bone was applied uniform properties. Loads representing 45° and 75° of abduction were then applied, and the resulting differentials in bone stress versus the corresponding intact state and the expected time-zero bone response were determined and compared. The superolateral position reduced resorbing potential in the lateral cortex and increased resorbing potential in the lateral trabecular bone, while the inferomedial position produced the same effects but in the medial quadrant. For the inferomedial position, full backside contact with the resection plane was best in terms of changes in bone stress and expected bone response, although a small region of the medial cortex did experience no load transfer. The implant-bone load transfer of the inferior contact condition was concentrated at the midline of the backside of the humeral head, leaving the medial aspect largely unloaded as a result of the lack of lateral backside support. This study shows that inferomedial humeral head positioning loads the medial cortex at the cost of unloading the medial trabecular bone, with the same occurring for the superolateral position except that the lateral cortex is loaded at the cost of unloading the lateral trabecular bone. Inferomedial positioned heads also were predisposed to humeral head lift-off from the medial cortex, which may increase the risk of calcar stress shielding. For the inferomedial head position, full contact between the implant and resection plane was preferable. [ABSTRACT FROM AUTHOR]

Background: Implant manufacturers typically offer several sizes of a humeral stem for shoulder arthroplasty so that time zero fixation can be achieved with the optimal size. Stem size can be templated preoperatively but is definitively determined intraoperatively. The purpose of this study was to determine if preoperatively acquired parameters, including patient demographics and imaging, could be used to reliably predict intraoperative humeral stem size. Methods: A cohort of 290 patients that underwent shoulder arthroplasty (116 anatomic and 174 reverse) was analyzed to create a regression formula to predict intraoperative stem size. The initial cohort was separated into train and test groups (randomly selected 80% and 20%, respectively). Patient demographics, anatomical measurements, and statistical shape model parameters determined from a preoperative shoulder arthroplasty planning software program were used for multilinear regression. The implant used for all cases was a short-stemmed metaphyseal-fit prosthesis. Results: Metaphyseal bone density, humeral statistical shape model parameters, and humeral intramedullary canal diameter were identified as highly predictive of intraoperative final humeral prosthesis size. On the train group, a coefficient of determination R2 of 0.63 was obtained for the multilinear regression equation combining these parameters. When analyzing the cohort for the prediction of stem size in the test group, 95% were within plus or minus one size of that used during surgery. Conclusion: Preoperative criteria such as humeral geometry and proximal humeral bone density can be combined in a single multilinear equation to predict intraoperative humeral stem size within one size variation. Embedding the surgeon’s decision-making process into an automated algorithm potentially allows this process to be applied across the surgical community. Predicting intraoperative decisions such as humeral stem size also has potential implications for the management of implant stocks for both manufacturers and health-care facilities.

The successive refinement in implant design and operative technique alongwith improved understanding has resulted in increased incidence of total shoulder arthroplasty (TSA). Simultaneously, the indications of TSA have widened and include a range of shoulder pathologies. Using the keywords and relevant literature, we have described an overview of the different stem sizes used in shoulder arthroplasty. Relevant description of clinical and radiological outcome is done with regards to different stem sizes. There are plethora of shoulder replacement systems, based on unique philosophy and having their own advantages and disadvantages. Additionally, the rise in ageing population had increased the need for revision TSA, thereby necessitating the judicious choice of implant at primary TSA. We further present the role of cemented and uncemented humeral stems and discuss the findings of finite element analysis. The choice of humeral stem size and use of cemented or uncemented stems have been reported to affect the clinical and radiological outcomes. [ABSTRACT FROM AUTHOR]

Fatigue failure of the humeral stem is a severe long-term failure after shoulder arthroplasty, causing harm to patients and resulting in complex revision surgeries. However, there are few studies on humeral stem fatigue testing, and corresponding testing standards have not been established. Therefore, this study aims to investigate the fatigue performance of the humeral stem by establishing an efficient numerical simulation method. Material properties are obtained by uniaxial tensile and fatigue tests. A parameterized static analysis program was written, and an automated fatigue numerical simulation platform was established using Abaqus, Fe-safe, and Isight in combination, enabling the establishment of a numerical simulation method for the fatigue performance of the humeral stem. Standard testing conditions include an 8 mm diameter humeral stem, a 40-21B humeral head, an 8° tilt angle, and a 2 mm fillet radius. Further research found that the fatigue life of the humeral stem decreases with increasing patient weight, and patients should control their weight after surgery. The established automated fatigue numerical simulation platform avoids repetitive operations and efficiently completes large-scale calculations, guiding preoperative humeral stem selection and testing. [ABSTRACT FROM AUTHOR]

Variations in humeral component designs in hemiarthroplasty and anatomic total shoulder arthroplasty cases can impact the degree of difficulty during a revision surgery that necessitates the removal of the humeral stem. However, no metric exists to define stem extraction effort nor to identify associated factors that contribute to extraction difficulty. The purpose of this study is to describe a method to quantify stem extraction difficulty and to define features that will impact the effort during stem removal. This was a retrospective review of 58 patients undergoing revision of hemiarthroplasty or anatomic total shoulder arthroplasty requiring stem extraction. Each included patient had existing preoperative radiographic examination, an intraoperative video of the stem removal process, and explants available for analysis by 3 surgeons. The following factors were assessed for the impact on extraction difficulty: (1) preoperative features such as cement use, fill of proximal humerus, and stem design features; (2) intraoperative data on extraction time and bone removal; and (3) postoperative findings related to extraction artifacts (EAs). A scoring system was established to distinguish easy (Easy group) and difficult (Difficult group) stem removal cases and further used to identify the features that may affect intraoperative difficulty of stem removal. The Difficult group accounted for 26% (15/58) of the study population with an 18-minute average stem extraction time, average EA count of 69, and 35 mm of bone removed. The Easy group accounted for 74% (43/58) of patients, with a 4-minute average extraction time, average EA count of 23, and 10 mm of bone removed. Logistic regression model was able to correctly classify 82% of the cases, explaining 26.7% of the variance in humeral stem removal with cement and proximal coating variables. The likelihood of cemented stem removal being difficult is 5 times greater compared to an uncemented stem, and having proximal coating doubles the likelihood of a difficult stem removal compared to cases with no coating. Quantifying stem extraction difficulty is possible with intraoperative video as well as explant analysis. Preoperative features of the fixation type and specific features of stem design such as proximal coating will impact difficulty of stem extraction. [ABSTRACT FROM AUTHOR]

Purpose: Some patients show severe humeral bone stress shielding even one year after press-fit humeral stem, which can be a risk factor for implant durability. This study compared humeral stress shielding and clinical outcomes between high and low filling ratio (HFR and LFR) stems in primary reverse shoulder arthroplasty (RSA).Methods: From 2015 to 2020, 104 patients who underwent RSA with a non-cemented standard-length humeral stem were examined. The humeral stems included large press-fit stems (HFR group, 53 patients) or small non-press-fit stems with autogenous cancellous bone grafting (LFR group, 51 patients). The radiologic and clinical outcomes were compared between the groups one year post-operatively.Results: One patient in the LFR group with early infectious dislocation was excluded from the 1-one year evaluation. No stress shielding was observed in 27/50 (54.0%) and 5/53 (9.4%) of patients in the LFR and HFR groups, while 3/50 (6%) and 19/53 (35.8%) patients showed high-stress shielding, respectively. However, the stem alignment change, subsidence, complications and evidence of loosening did not differ between the groups. The final range-of-motion and functional scores were significantly poorer in the LFR group than those in the HFR group, although the difference was minimal.Conclusion: Even at one year follow-up, patients receiving LFR stems with autogenous bone grafting had significantly less humeral stress shielding compared to patients with HFR stem with press-fit in primary RSA, without compromising stem stability. [ABSTRACT FROM AUTHOR]

While short stems in total shoulder arthroplasty (TSA) preserve bone stock and facilitate revision surgery, they have been associated with higher rates of malalignment and loosening in some cases compared to standard length stems. The purpose of this study was to analyze the intramedullary canal in progressive increments distal to the greater tuberosity to provide anatomic information about the optimal length of press-fit short stems for alignment and stability in TSA. We hypothesized that the humeral canal diameter will remain variable for the first 50 to 75 mm distal to the greater tuberosity and will become consistent thereafter. A retrospective review of 99 consecutive patients undergoing TSA with CT scans was performed. Intramedullary anterior-posterior (AP) and medial-lateral (ML) width as well as diameter were analyzed on two-dimensional computed tomography following multiplanar reconstruction. Measurements were taken at consistent distances distal to the greater tuberosity (GT). The transition point was measured at the proximal level of the humerus where endosteal borders of the medial and lateral cortices became parallel. The mean transition point was 73 mm from the GT (range: 53 to 109 mm). ML and AP widths became consistent 80 mm distal to the GT. IM diameter became consistent after 90 mm distal to the GT and a stem length of 90 mm extended past the transition point in 91.9% of cases. In TSA, a humeral stem length of 90 mm is required to predictably reach points at which the humeral canal becomes cylindrical and consistent in diameter. This information may aid data-driven decisions on humeral stem length during press-fit fixation, assuring consistency of alignment and implant stability, while maintaining ease of revision associated with a short stem implant. Level of evidence: III [ABSTRACT FROM AUTHOR]

Background: Stress shielding of the humeral stem is a known complication in press-fit total shoulder arthroplasty (TSA), but there remain limited data on its prevalence and clinical impact in midterm follow-up. The purpose of this study was to determine the prevalence of humeral stem stress shielding and its impact on functional outcomes at minimum 5-year follow-up in standard length press-fit TSA. The hypothesis was that the presence of stress shielding at minimum 5-year follow-up would not affect functional outcome scores or range of motion (ROM). Methods: A multicenter retrospective review of primary TSAs performed with a press-fit standard length humeral stem. Functional outcome scores, ROM, and radiographs were reviewed at minimum 5-year follow-up. Prevalence of stress shielding was determined by presence of medial calcar osteolysis and adaptive changes. Function was assessed with the visual analog scale (VAS) pain score, Simple Shoulder Test (SST) score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, and Single Assessment Numeric Evaluation (SANE) score, and ROM. Results: Forty-seven patients with 47 TSAs were available for follow-up at a mean of 79 months postoperation. Overall, 15 of 47 humeral stems had high adaptive change scores (31.9%), and 20 demonstrated medial calcar osteolysis (42.6%). Stems with evidence of stress shielding showed no significant change in SST, VAS, ASES, or SANE scores and minimal change in ROM measurements at minimum 5-year follow-up. Conclusion: Stress shielding is common at midterm follow-up in press-fit TSA but does not appear to affect functional outcomes.

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The purpose of this study was to evaluate the relative contribution of the reverse shoulder arthroplasty (RSA) humeral stem length on initial implant fixation, which may contribute to the long-term success of uncemented shoulder implants. Three RSA humeral components were randomly divided into the following testing groups: (1) 100% Stem length (n = 7); (2) 50% Stem length (n = 7); (3) 0% Stem length (n = 7). Each humeral stem was press-fit into twenty-one 4th Generation Osteoporotic Sawbones humeri. Torque and compressive axial load were applied to the humerus for 10,000 cycles at ±2.5 Nm and −392 N, respectively. Rotational micromotion of the implant was measured. Micromotion for all 3 testing groups was below the 150 µm micromotion threshold throughout testing. The overall micromotion in Group 2 was significantly larger than Group 1 (P <.001) and Group 3 (P <.001). Overall micromotion between Group 1 and Group 3 were not significantly different (P =.686). All stem lengths studied maintained micromotion below the 150 µm threshold, suggesting that any of these treatment groups would provide adequate initial fixation to allow bony on-growth. Clinically, stemless or short-stemmed prosthesis design offer theoretical benefits such as the degree of freedom for humeral stem placement independent of diaphysis. This study concluded that the zero-length stem will allow for this and provide adequate fixation comparable to the full-length stem. Basic Science Study. [ABSTRACT FROM AUTHOR]

Introduction: Shorter humeral reverse total shoulder arthroplasty (RTSA) stems may reduce stress shielding, however, potentially carry the risk of varus/valgus malalignment. This radiographic study's purpose was to measure the incidence of stem malalignment and thus the realized neck-shaft angle (NSA). The hypothesis was that malalignment of the stem is a frequent postoperative radiographic finding.Methods: Radiographs of an uncemented curved short stem RTSA with a 145° NSA were reviewed. The study group included 124 cases at a mean age of 74 (range 48-91) years. The humeral stem axis was measured and defined as neutral if the value fell within ± 5° of the longitudinal humeral axis. Angular values > 5° were defined as malaligned in valgus or varus. The filling ratio of the implant within the humeral shaft was measured at the level of the metaphysis (FRmet) and diaphysis (FRdia).Results: The average humeral stem axis angle was 4 ± 3° valgus, corresponding to a true mean NSA of 149 ± 3°. Stem axis was neutral in 73% (n = 90) of implants. Of the 34 malaligned implants, 82% (n = 28) were in valgus (NSA = 153 ± 2°) and 18% (n = 6) in varus (NSA = 139 ± 1°). The average FRmet and FRdia were 0.68 ± 0.11 and 0.72 ± 0.11, respectively. A low positive association was found between stem diameter and filling ratios (r = 0.39; p < 0.001); indicating smaller stem sizes were more likely to be misaligned.Conclusion: Uncemented short stem implants may decrease stress shielding; however, approximately one quarter were implanted > 5° malaligned. The majority of malaligned components (86%) were implanted in valgus, corresponding to an NSA of > 150°. As such, surgeons must be aware that shorter and smaller stems may lead to axial malalignment influencing the true SA.Level Of Evidence: Level IV, retrospective study. [ABSTRACT FROM AUTHOR]

Reverse shoulder arthroplasty (RSA) is a reliable, long-term treatment option for degenerative shoulder pathology. However, the functional outcomes degrade around the fifth year postoperation, particularly for internal and external rotation. Long-term radiographic changes have been reported around the humeral stem, depending on the fixation method. The primary objective was to compare the clinical outcomes of RSAs by fixation method—cemented vs. press-fit—after a minimum follow-up of 5 years. We hypothesized that proximal humeral osteolysis impacts the functional outcomes. Our study compared 2 matched cohorts: 56 RSAs with cemented stems and 56 RSAs with press-fit stems. We evaluated all the patients using the Constant-Murley score (CMS) and range of motion (ROM), which we measured preoperatively and at the final follow-up visit. We evaluated radiographs from the final follow-up visit to look for proximal humeral osteolysis with tuberosity resorption, signs of stress shielding, periprosthetic radiolucent lines, and scapular notching. At a mean follow-up of 9.5 years (5-21), regardless of the fixation method, the RSA procedure helped to improve the CMS and active joint ROM postoperatively, except for internal and external rotation with elbow at side in the press-fit group. Shoulder ROM was significantly better in the group with cemented stems for anterior elevation (P <.001), abduction (P =.006), and external (P =.02) and internal rotation with elbow at side (P =.02). The CMS did not differ between groups. The presence of tuberosity resorption or scapular notching had no effect on the CMS and active ROM in either group. Osteopenia, which was more prevalent in the press-fit group, had no impact on the functional outcome. There was no significant difference between groups in the CMS, although the active shoulder ROM was significantly worse in the press-fit group. This difference could be attributed to more frequent tuberosity resorption in this group. [ABSTRACT FROM AUTHOR]

Reverse shoulder arthroplasties have progressed in recent decades to become the most popular type of arthroplasty. Short stems with metaphyseal fixation have been developed to preserve bone stock and facilitate possible revision. Accurate positioning of these implants can be challenging using the superolateral approach. This study aimed to evaluate the clinical and radiologic results of reverse short-stem arthroplasties using a superolateral approach with a minimum of 2 years' follow-up. Between January 2015 and December 2016, a total of 76 patients underwent reverse shoulder arthroplasty surgery (79 shoulders) using a short uncemented humeral stem for shoulder arthritis with irreparable rotator cuff tear. Arthroplasties for post-traumatic osteoarthritis were excluded. Functional outcomes were assessed using Constant Score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), visual analog scale (VAS), and range of motion. Radiographic analysis was used to evaluate component loosening, implant position, and implant filling ratio. The mean age was 70.8 years. At a mean of 38.8-month follow-up, there were significant improvements in Constant score (44.2 to 87.9, P <.001), ASES score (36.2 to 84.3, P <.001), and VAS score (6.8 to 0.4, P <.001). Forward flexion improved from 89°to 131°(P <.001), and external rotation improved from 25° to 36°(P <.001). No evidence of periprosthetic loosening was visible. Mean varus of the humeral stem was 1°(±6°). The mean glenoidal inclination was 98°(±7°), which corresponds to a lower tilt of 8°. The average filling ratio was between 50% and 60% in both the metaphysis and the diaphysis. The clinical results obtained in this study were satisfying, with a significantly low complication rate. Hence, short-stem reverse shoulder arthroplasty using a superolateral approach, while taking particular care to protect the deltoid, remains our method of choice. [ABSTRACT FROM AUTHOR]

Several humeral stem design modifications for shoulder arthroplasty, including reduced stem length, changes to metaphyseal geometry, and alterations to implant surface texture, have been introduced to reduce stress shielding. However, the effect of changes in the diametral size of short-stem humeral components remains poorly understood. The purpose of this finite element study was to quantify the effect of varying the size of short-stem humeral components on the changes in bone stress from the intact state to the reconstructed state. Three-dimensional models of 8 male cadaveric humeri (mean age, 68 ± 6 years; all left-sided humeri) were constructed from computed tomography data using Mimics software. Each humerus was then reconstructed with 2 short-stem components (Exactech Preserve), one having a larger diametral size (SH+) and one having a smaller diametral size (SH–). Modeling was conducted for loading states consistent with 45° and 75° of abduction, and the resulting changes in bone stress compared with the intact state and the expected bone response were determined. The smaller (SH–) short-stem implant produced humeral cortical and trabecular bone stresses that were closer to the intact state than the larger (SH+) short-stem implant at several locations beneath the humeral head resection (P ≤.032). A similar trend was observed for expected bone response, where the smaller (SH–) short-stem implant had a smaller proportion of bone that was expected to resorb following reconstruction compared with the larger (SH+) short-stem implant for several slice depths in the medial quadrant (P ≤.02). These findings may indicate that smaller short-stem components are favorable in terms of stress shielding. [ABSTRACT FROM AUTHOR]

Background Several short-stemmed press-fit humeral components have been developed in recent years for anatomic total shoulder arthroplasty (TSA) as well as reverse shoulder arthroplasty (RSA). Varying radiographic outcomes have been reported, with some studies reporting concerning rates of aseptic loosening. This study analyzed the radiographic findings of a press-fit convertible short-stemmed humeral component in both TSA and RSA. Methods There were 150 anatomic TSAs (group 1) and 77 RSAs (group 2) analyzed radiographically at a minimum follow-up of 2 years postoperatively. Plain radiographs were reviewed for stem loosening, alignment, signs of stress shielding, and the filling ratio. Results At final follow-up, 49% of group 1 and 65% of group 2 had no evidence for radiographic changes. In those with radiographic changes, low bone adaptions were found in 83% and high adaptions in 17% in both groups. Larger stem sizes with higher filling ratios were associated with high radiographic adaptions in both groups (P =.02). The overall filling ratios were higher in group 2 (P =.002). Cortical contact of the stem led to higher bone adaptions (P =.014). Conclusions The short humeral component analyzed in this study showed encouraging survival rates without aseptic loosening. Radiographic changes are associated with a higher filling ratio and cortical contact of the stem. Surgeons should aim to achieve fixation with the minimal required canal filling to minimize radiographic changes with the uncemented humeral component used in this study. [ABSTRACT FROM AUTHOR]

Anatomical total shoulder arthroplasty in its modern form where it reproduces the normal shoulder has been utilized clinically for more than half a century. As the technology and the designs have changed to recreate the humeral and glenoid sides of the joint, the sophistication of design has resulted in the growing number of cases annually worldwide. This increase is due in part to the increasing number of indications that the prosthesis can treat with successful results. On the humeral side, there have been design changes to better reflect the proximal humeral anatomy, and humeral stems are increasingly placed safely without cement. Platform systems which allow conversion of a failed arthroplasty to a reverse configuration without stem extraction is another design change. Similarly, there has been increasing utilization of short stem and stemless humeral components. Extensive experience with shorter stem and stemless devices, however, has yet to demonstrate the purported advantages of these devices, as recent studies have demonstrated equivalent blood loss, fracture rates, operative times, and outcome scores. Easier revision with these shorter stems remains to be definitively established, with only one study comparing the ease of revision between stem types. On the glenoid side, hybrid cementless glenoids, inlay glenoids, cementless all-polyethylene glenoids, and augmented glenoids have all been investigated; however, the indications for these devices remain unclear. Lastly, innovative surgical approaches to implanting shoulder arthroplasty and the use of patient specific guides and computerized planning, while interesting concepts, still await validation before they are utilized on a widespread basis. While reverse shoulder arthroplasty has been increasingly used to reconstruct the arthritic shoulder, anatomic glenohumeral replacement maintains a significant role in the armamentarium of the shoulder surgeon., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background The influence of primary humeral stem fixation method (cemented or press fit) on intraoperative or postoperative outcomes in the setting of revision shoulder arthroplasty is unknown. Methods A retrospective analysis of a prospectively collected cohort of revision shoulder arthroplasty patients from a single tertiary center was performed. Demographic variables, intraoperative data, and 90-day complication rates were compared between cemented and press-fit primary stem fixation cohorts. Follow-up radiographs were graded and compared using a modified Gruen system for humeral lucencies. Results Eighty-six primary shoulder replacements (34 hemiarthroplasties, 39 anatomic total shoulder arthroplasties, 13 reverse total shoulder arthroplasties) underwent revision arthroplasty with humeral stem removal between 2004 and 2017. Forty-five patients had cemented primary humeral fixation and 41 had press-fit fixation. The cemented cohort was older than the cementless cohort (66.6 vs. 61.4 years; P  = .03) but otherwise demonstrated no difference in gender, body mass index, type of primary prosthesis (hemi, total, or reverse), or time between primary and revision operations. The cemented and cementless cohorts showed similar rates of humeral osteotomy (28.9% vs. 29.3%; P  = .97), operative time (133.5  vs. 121.3 minutes; P  = .16), and 90-day complication rates (13.3% vs. 9.8%; P  = .61). Cemented vs. press-fit primary stems also had similar rates of humeral lucencies seen on follow-up radiographs after revision (77.1% vs. 60.6%; P  = .14). Conclusion Humeral stem fixation with or without cement during primary shoulder arthroplasty demonstrated similar operative time, need for intraoperative humeral osteotomy, and postoperative complication rates in the setting of revision arthroplasty. [ABSTRACT FROM AUTHOR]

Revision total shoulder arthroplasty is performed for a variety of patient symptoms, including shoulder pain, instability, or stiffness. The technical reasons found for revision include component loosening or malposition. Removing the humeral stem during revision can increase morbidity and blood loss during a procedure. The ability to use a universal stem that can be utilized in both anatomic and reverse shoulder arthroplasty can be beneficial in three main areas. For revision surgeries, cost is much less, OR time is decreased, and complications are much less frequent. [ABSTRACT FROM AUTHOR]

Background: Aseptic implant loosening is one of the most common complications leading to revision surgery in total elbow arthroplasty. Different humeral stem lengths are available with varying designs. In general, the decision of which stem length to use depends on the surgical diagnosis or simply the surgeon preference. Often, the longer stem is used for post-traumatic or revision cases while for rheumatoid patients the shorter stem is preferred. There are no data in the literature to favor one humeral stem size over the other according to the diagnosis. Methods: We analyzed the total elbow joint database of the Coonrad-Morrey design at our institution for aseptic loosening leading to revision and compared the revision rate and the survival of the 4- and 6-inch humeral stems. Results: Overall, revision for aseptic humeral loosening is infrequent and occurred in only 16 of 711 total elbow arthroplasties during a mean follow-up of 88 months. There was no significant difference in the revision rate between the 2 stem lengths (1.9% for the 4-inch stems and 2.6% for the 6-inch stem). Conclusion: Revision rate was correlated to the surgical diagnosis and was significantly higher for post-traumatic patients than for rheumatoid patients (5.1% vs 0.66%, P < .001). Of interest, and possibly not surprising, the mean time to revision was shorter for the 4-inch stems than it was for the 6-inch stems (37 vs 95 months, P = .034). [Copyright &y& Elsevier]

Background: The successive refinement in implant design and operative technique alongwith improved understanding has resulted in increased incidence of total shoulder arthroplasty (TSA). Simultaneously, the indications of TSA have widened and include a range of shoulder pathologies., Methods: Using the keywords and relevant literature, we have described an overview of the different stem sizes used in shoulder arthroplasty. Relevant description of clinical and radiological outcome is done with regards to different stem sizes., Discussion: There are plethora of shoulder replacement systems, based on unique philosophy and having their own advantages and disadvantages. Additionally, the rise in ageing population had increased the need for revision TSA, thereby necessitating the judicious choice of implant at primary TSA. We further present the role of cemented and uncemented humeral stems and discuss the findings of finite element analysis. The choice of humeral stem size and use of cemented or uncemented stems have been reported to affect the clinical and radiological outcomes., Competing Interests: None., (© 2022 Published by Elsevier B.V. on behalf of Professor P K Surendran Memorial Education Foundation.)

Background: Implant manufacturers typically offer several sizes of a humeral stem for shoulder arthroplasty so that time zero fixation can be achieved with the optimal size. Stem size can be templated preoperatively but is definitively determined intraoperatively. The purpose of this study was to determine if preoperatively acquired parameters, including patient demographics and imaging, could be used to reliably predict intraoperative humeral stem size., Methods: A cohort of 290 patients that underwent shoulder arthroplasty (116 anatomic and 174 reverse) was analyzed to create a regression formula to predict intraoperative stem size. The initial cohort was separated into train and test groups (randomly selected 80% and 20%, respectively). Patient demographics, anatomical measurements, and statistical shape model parameters determined from a preoperative shoulder arthroplasty planning software program were used for multilinear regression. The implant used for all cases was a short-stemmed metaphyseal-fit prosthesis., Results: Metaphyseal bone density, humeral statistical shape model parameters, and humeral intramedullary canal diameter were identified as highly predictive of intraoperative final humeral prosthesis size. On the train group, a coefficient of determination R 2 of 0.63 was obtained for the multilinear regression equation combining these parameters. When analyzing the cohort for the prediction of stem size in the test group, 95% were within plus or minus one size of that used during surgery., Conclusion: Preoperative criteria such as humeral geometry and proximal humeral bone density can be combined in a single multilinear equation to predict intraoperative humeral stem size within one size variation. Embedding the surgeon's decision-making process into an automated algorithm potentially allows this process to be applied across the surgical community. Predicting intraoperative decisions such as humeral stem size also has potential implications for the management of implant stocks for both manufacturers and health-care facilities., (© 2022 The Author(s).)

Press fit fixation is becoming more popular in RSA to preserve, in theory, bone capital. Several studies report that bone resorption can be very high around humeral stems depending on their size, shape and mode of fixation. The aim of the current study is to mid-term follow-up clinical and radiological result of a press fit ovoid regular stem RSA in non acute trauma cases., Materials and Methods: We performed a retrospective monocentric study of patients continuously implanted with the Humeris® stem RSA for degenerative change of the shoulder. Nineteen shoulders, in eighteen patients (74.6 y.o (from 69 to 81)), were available at minimum five years follow-up., Results: The mean final adjusted Constant score was 111.9 (65 to 130), and the mean ASES score was 49.82 (10 to 60). Humeral resorption was observed in 21% of cases. We found a statistically significant ( p  = .014) lower adjusted Constant score in patients presenting with resorption on post-operative X-rays compared to those without resorption (115.6 vs. 98.25). Half cases of patients presenting a resorption underwent L'Episcopo procedure during surgery. Humeral resorption occurs the first year after surgery and do not increase even 8 years after surgery. Analysis demonstrated no correlation between the value of filling ratios and bone resorption., Conclusion: The current study confirms a low rate of stress shielding around the studied stem, with rare bony resorption and no osteopenia around the humeral stem. This study highlights the importance of choosing the appropriate proximal shape and length of the humeral stem for press fit fixation in RSA., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Geoffroy Nourissat and Howard Harris are consultant for FX Shoulder solution, (© The Author(s) 2022.)

Background: Press-fit humeral components for total shoulder arthroplasty have notable potential complications that may be minimized by preoperative templating and improvements in stem design. The purpose of this study was to develop a 3-dimensional templating technique for the humeral stem and to validate this templating in cadaveric specimens. Materials and methods: A cylindrical stem and a stem with a rectangular cross-section were selected for templating and force measurements. Templating was carried out for 15 clinical patients and 16 cadaveric shoulders, including calculation of the cortical-implant volume ratio (CIVR). Insertion forces for stem broaching and impaction were measured for 15 patients and 8 paired cadaveric shoulders. Hoop strain and periprosthetic fractures were monitored in cadaveric shoulders with strain gauges. Results: A significant difference in the CIVR was noted between rectangular and cylindrical stems. No difference was observed in impact forces for ideally sized rectangular or cylindrical stems. A difference in insertion forces was found between oversized cylindrical and oversized rectangular implant stems and also between ideal and oversized cylindrical implant stems. The difference in maximal hoop strain between ideally sized rectangular and cylindrical stems was also statistically significant. Conclusions: CIVR is useful to predict an ideal humeral stem size. Cylindrical stems have a different design rationale for fixation than rectangular stems. Surgeon awareness of the fixation rationale for a particular stem design is important because different stem types have different effects on the insertion force. More anatomic humeral stem designs may help to minimize the risk of complications and optimize stem fixation. [ABSTRACT FROM AUTHOR]

Cemented humeral stem fixation in shoulder joint arthroplasty has been, and continues to be the “gold standard” to ensure satisfactory implant orientation and stability. The most commonly performed type of shoulder arthroplasty is hemi-arthroplasty in the face of comminuted fracture. Appropriate stem height and version relative to the glenoid is paramount in obtaining a satisfactory result. This has been proven to be reliably reproducible through cement fixation of the stem with careful reattachment of the tuberosities. Total shoulder arthroplasty in rheumatoid patients with questionable bone stock likewise has relied upon “cementation” of the humeral component to ensure secure fixation, prevent loosening and avoid subsidence. In younger patients it is tempting to want to avoid cement in the proximal humerus, nonetheless most studies have demonstrated loosening of the humeral component not to be problematic once cement has been used. In addition, newer modular componentry allows head removal (without stem removal) providing ready access to the glenoid should glenoid revision be needed. The ability to add antibiotics within the cement mantle in high-risk patients additionally affords an advantage in treating and/or avoiding infection. Survivorship studies have not demonstrated any advantage of cementless versus cement fixation of the humeral component in shoulder arthroplasty. Temporizing techniques such as cup arthroplasty and hybrid techniques such as placing tantalum weave surfaces proximally for enhanced tuberosity fixation may have a role, but do not replace the long-standing efficacy of cement fixation of the humeral component in the vast majority of patients requiring shoulder arthroplasty. [ABSTRACT FROM AUTHOR]

Background: A flanged humeral stem design can be advantageous in achieving an interlock between the prosthetic and bone interface leading to a long-term stable loading pattern. The purpose of this study is to report a short case series involving revision of a flanged humeral prosthesis. Our hypothesis was that a greater percentage of the flanged prostheses undergoing revision would require some form of bone expansion to achieve stem removal compared to the nonflanged. Methods and Results: In the period from October 2004 to July 2008, 43 patients underwent revision of a humeral prosthetic stem by a single surgeon. Of these, 6 prostheses were of a triflanged design. Of these six, five (83%) could not be removed with longitudinal force and required some expansion of the bone in order to achieve stem extraction. Of the nonflanged humeral stems, 3/37 (8%) required bone expansion to achieve extraction. Analysis of the 2 groups showed a statistical difference in the need for humeral expansion (P < .000001). Conclusions: Surgeons preparing to revise a flanged humeral stem should include expansion of the humeral shaft, by episiotomy or windowing, as part of their preoperative planning and informed consent of the patient. Level of evidence: Level IV, Case Series, Treatment Study. [Copyright &y& Elsevier]

There is an increasing shift toward the use of uncemented stems in total shoulder arthroplasty (TSA) and a rapidly growing collection of stem designs and geometries. However, there are limited data in the literature analyzing the performance or the optimal fixation technique of these various designs. Twenty-nine patients underwent TSA with a press-fit humeral stem using cancellous fixation. Radiostereometric analysis was used to detect stem loosening postoperatively. At 2-year follow-up, radiolucencies were detected in 4 of 26 stems with no clinical evidence of component loosening. Cancellous fixation of the humeral stem appears adequate for a stable bone–prosthesis interface in TSA. [ABSTRACT FROM AUTHOR]

Background: Stress shielding of the humeral stem is a known complication in press-fit total shoulder arthroplasty (TSA), but there remain limited data on its prevalence and clinical impact in midterm follow-up. The purpose of this study was to determine the prevalence of humeral stem stress shielding and its impact on functional outcomes at minimum 5-year follow-up in standard length press-fit TSA. The hypothesis was that the presence of stress shielding at minimum 5-year follow-up would not affect functional outcome scores or range of motion (ROM)., Methods: A multicenter retrospective review of primary TSAs performed with a press-fit standard length humeral stem. Functional outcome scores, ROM, and radiographs were reviewed at minimum 5-year follow-up. Prevalence of stress shielding was determined by presence of medial calcar osteolysis and adaptive changes. Function was assessed with the visual analog scale (VAS) pain score, Simple Shoulder Test (SST) score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, and Single Assessment Numeric Evaluation (SANE) score, and ROM., Results: Forty-seven patients with 47 TSAs were available for follow-up at a mean of 79 months postoperation. Overall, 15 of 47 humeral stems had high adaptive change scores (31.9%), and 20 demonstrated medial calcar osteolysis (42.6%). Stems with evidence of stress shielding showed no significant change in SST, VAS, ASES, or SANE scores and minimal change in ROM measurements at minimum 5-year follow-up., Conclusion: Stress shielding is common at midterm follow-up in press-fit TSA but does not appear to affect functional outcomes., (© 2019 The Author(s).)

Aims: A number of methods have been described to remove a well-fixed humeral implant as part of revision shoulder arthroplasty. These include the use of cortical windows and humeral osteotomies. The router bit extraction technique uses a high-speed router bit to disrupt the bone-implant interface. The implant is then struck in a retrograde fashion with a square-tip impactor and mallet. The purpose of this study was to determine the characteristics and frequency of the different techniques needed for the removal of a well-fixed humeral stem in revision shoulder arthroplasty., Patients and Methods: Between 2010 and 2018, 288 revision shoulder arthroplasty procedures requiring removal of a well-fixed humeral component were carried out at a tertiary referral centre by a single surgeon. The patient demographics, indications for surgery, and method of extraction were collected., Results: Of the 288 revisions, 284 humeral stems (98.6%) were removed using the router bit extraction technique alone. Four humeral stems (1.39%) required an additional cortical window. Humeral osteotomy was not necessary in any procedure. Most of the humeral stems removed (78.8%) were cementless. Of the four humeral stems that required a cortical window, three involved removal of a hemiarthroplasty. Two were cemented and two were cementless., Conclusion: The router bit extraction technique removed a well-fixed humeral component in a very high proportion of patients (98.6%). This method allows surgeons to avoid more invasive approaches involving a cortical window or humeral osteotomy, and their associated complications. Cite this article: Bone Joint J 2019;101-B:1280-1284.

Uncemented press-fit humeral stems were developed with the goal of decreasing operative time, preserving bone stock, and easing revision. In recent years, short stems and stemless humeral implants have also become available. These press-fit humeral implants have varying designs that can lead to changes in stress distribution in the proximal humerus. Such stress shielding manifests as bony adaptations and may affect long-term functional outcome and the ability to perform revision. However, current studies of humeral fixation during total shoulder arthroplasty are complicated because a variety of classification systems have been used to report findings. The purpose of this report is to review the current literature on press-fit fixation of the humeral component during total shoulder arthroplasty and propose minimum requirements for radiographic descriptions of stress shielding., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Recent experiences with Grammont reverse shoulder arthroplasty (RSA) have revealed some problems related to the biomechanical changes of the shoulder and humeral stem complications. We analyzed humeral complications in a long-term follow-up of a large series of RSAs, searching for correlations between these and the initial etiology, the follow-up duration, and the clinical outcomes., Materials and Methods: Preoperative and postoperative clinical and radiologic assessments of 1035 RSAs with a minimum 5-year follow-up (implanted in 7 specialized shoulder centers between 1993 and 2010) were retrospectively collected. Postoperative humeral complications, managed conservatively or surgically, were radiographically documented., Results: Overall, a 3.3% rate of postoperative humeral complications was found in our database. We identified 17 cases (1.6%) with postoperative humeral fractures, 15 cases (1.4%) with aseptic humeral loosening, and 3 cases (0.3%) with humeral stem disassembly. The humeral complications were more frequent in RSAs implanted for tumors, fracture sequelae, and revision for failed arthroplasty., Discussion: Humeral complications after RSA are not rare, increase with longer follow-up, and have a negative impact on functional outcomes. Postoperative humeral fractures are more frequent in elderly patients, operated on through a superior approach, and after cemented stem implantation. In the absence of associated humeral loosening, conservative treatment should be preferred. Proximal humeral bone loss (due to revisions and tumors) is the most significant risk factor for humeral loosening. Implant unscrewing was initially related to a technological problem, which has been solved, and this complication has disappeared., (Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)