This paper presents an ongoing review of the use of a wedge-shaped porous metal augments in the shoulder to address glenoid retroversion as part of anatomical total shoulder arthroplasty (aTSA). Seventy-five shoulders in 66 patients (23 women and 43 men, aged 42 to 85 years) with Walch grade B2 or C glenoids underwent porous metal glenoid augment (PMGA) insertion as part of aTSA. Patients received either a 15º or 30º PMGA wedge (secured by screws to the native glenoid) to correct excessive glenoid retroversion before a standard glenoid component was implanted using bone cement. Neither patient-specific guides nor navigation were used. Patients were prospectively assessed using shoulder functional assessments (Oxford Shoulder Score [OSS], American Shoulder and Elbow Standardized Shoulder Assessment Form [ASES], visual analogue scale [VAS] pain scores and forward elevation [FE]) preoperatively, at three, six, and 12 months, and yearly thereafter, with similar radiological surveillance. Forty-nine consecutive series shoulders had a follow-up of greater than 24 months, with a median follow-up of 48 months (range: 24–87 months). Median outcome scores improved for OSS (21 to 44), ASES (24 to 92), VAS (7 to 0), and FE (90º to 140º). Four patients died, but no others were lost to follow-up. Apart from one infection at 18 months postoperatively and one minor peg perforation, there were no complications, hardware failures, implant displacements, significant lucency or posterior re-subluxations. Radiographs showed good incorporation of the wedge augment with correction of glenoid retroversion from median 22º (13º to 46º) to 4º. All but four glenoids were corrected to within the target range (less than 10º retroversion). The porous metal wedge-shaped augments effectively addressed posterior glenoid deficiency as part of aTSA for rotator cuff intact osteoarthritis, producing satisfactory clinical outcomes with no signs of impending future failure

Objective. We aimed to analyse the clinical outcomes and survivorship of anatomic total shoulder arthroplasty using a stemless humeral component with cemented pegged polyethylene glenoid performed with the technique of eccentric reaming to partially correct retroversion. These results were then compared with TSA using the same implant for end-stage shoulder arthritis with a normal version of the native glenoid. Design and methods. A retrospective case series was performed using a prospectively collected database of anatomic TSA patients operated at Woodend General Hospital, Aberdeen, UK. Between 2010 and 2019, 107 total shoulder arthroplasties (TSA) were done using standard anatomic stemless TSA implants (Affinis Short, Mathys Ltd, Bettlach, Switzerland) in 98 patients. Standardized preoperative and postoperative shoulder radiological imaging for glenoid retroversion was collected. Depending on the angle of native glenoid version, patients were divided into retroverted and non-retroverted glenoid as per the Walch Classification. To assess the radiological outcome at the final follow-up, radiolucency was assessed on the glenoid and humeral side using the Lazarus grading. The final clinical and radiologic outcome from the retroverted group was compared with the population with a non-retroverted glenoid. Five TSAs were excluded from the analysis as they did not have satisfactory postoperative radiographs. Hence, a total of 102 shoulders were available for analysis. Results. The mean follow-up was 3.48 years (2-10.2 years) in the retroverted group (n=44) and 3.9 years (2-8.9 years) in the non-retroverted group (n=58). The mean pre-operative retroversion of the glenoid in the retroverted group was 20.18, and the post-operative retroversion was 15.87, with a mean correction of 4.31. There was no significant difference between the two groups in the percentage of radiological loosening. The mean Oxford shoulder score was 41.4 (16-48) in the retroverted group, while it was 42.1 (20-48) in the non-retroverted group. Three patients in the retroverted group required revision surgery for rotator cuff failure. There were no revisions for aseptic loosening or instability. Conclusion. The degree of severity of retroversion of the glenoid was not associated with poor clinical outcomes, revisions, or failure in stemless TSA. At medium-term follow-up, partial correction of retroversion seems to provide comparable outcomes compared to a non-retroverted glenoid

Introduction. Despite the positive outcomes in shoulder joint replacements in the last two decades, polyethylene wear debris in metal-on-polyethylene artificial shoulder joints is well-known as a limitation in the long-term survival of shoulder arthroplasties systems. Consequently, there is an interest in the use of novel materials as an alternative to hard bearing surfaces such as pyrolytic carbon layer (PyroCarbon). Materials and Methods. In the present study, the unique Newcastle Shoulder Wear Simulator was used (Smith et al., 2015; Smith et al., 2016) to evaluate the wear behavior of four commercially available PyroCarbon humeral heads 43 mm diameter, articulating against conventional ultra-high molecular weight polyethylene (UHMWPE) glenoid inserts with a radius of curvature of 17.5 mm to form an anatomic total shoulder arthroplasty. A physiological combined cycled “Repeat-motion-load” (RML) (Ramirez-Martinez et al., 2019) obtained from the typical activities of daily life of patients with shoulder implants was applied as a simulator input. A fifth sample of the same size and design was used as a soak control and subjected to dynamic loading without motion during the wear test. The mean volumetric wear rate of PyroCarbon-on-polyethylene was evaluated over 5 million cycles gravimetrically and calculated on the basis of linear regression, as well as the change in surface roughness (S. a. ) of the components using a non-contacting white light profilometer throughout the test. Results. The gravimetric analysis showed a mean volumetric wear rate and standard deviation of 19.3±9.5 mm. 3. /million cycles for the UHMWPE glenoid inserts, whereas PyroCarbon humeral head counterparts did not exhibit a loss in mass throughout the test. The roughness values of the UHMWPE glenoid inserts decreased (P < .001), changing from 296±28 nm to 32±8 nm at the end of the test. In contrast, the PyroCarbon humeral heads did not show a significant change (P = .855) over the 5 million cycles; remained in the same range (21±2 nm to 20±10 nm) with no evidence of wear damage on the surface. Conclusions. This is the first in-vitro shoulder simulator study of a PyroCarbon on UHMWPE articulation. Wear rates were similar to that found to well-proven metal on UHMWPE shoulder arthroplasties. While it was interesting to see that the PyroCarbon did not roughen over the test duration, the lack of an appreciable reduction in wear of the UHMWPE component when articulated with an expensive and complex to manufacture PyroCarbon component likely means there is little clinical cost-benefit in the use of a PyroCarbon on UHMWPE shoulder implant. Declaration of competing interest. Prof. Ian A. Trail received some royalties and research support from Wright Medical Group N.V. None of the other authors, their immediate families, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article. For any figures or tables, please contact authors directly

INTRODUCTION. Preoperative planning software for anatomic total shoulder arthroplasty (ATSA) allows surgeons to virtually perform a reconstruction based off 3D models generated from CT scans of the glenohumeral joint. The purpose of this study was to examine the distribution of chosen glenoid implant as a function of glenoid wear severity, and to evaluate the inter-surgeon variability of optimal glenoid component placement in ATSA. METHODS. CT scans from 45 patients with glenohumeral arthritis were planned by 8 fellowship trained shoulder arthroplasty specialists using a 3D preoperative planning software, planning each case for optimal implant selection and placement. The software provided three implant types: a standard non-augmented glenoid component, and an 8° and 16° posterior augment wedge glenoid component. The software interface allowed the surgeons to control version, inclination, rotation, depth, anterior- posterior and superior-inferior position of the glenoid components in 1mm and 1° increments, which were recorded and compared for final implant position in each case. RESULTS. Five cases were excluded due to extreme glenoid wear. For resultant implant version, a bimodal distribution was observed with a local maxima occurring at 0 degrees, and a bell-shaped distribution at −5° of version. Upon individual surgeon analysis, it was revealed that certain surgeons had a preference to correct to 0 degrees, whereas others were more accepting of residual version. Shoulders ranged in native version from 0° to −27° with an average of −11°, indicating a high frequency of posterior glenoid wear. The frequency of different implants used for each degree of version shows that standard implants were never used when version was > −11°. Conversely, 16° augmented glenoids were never used when the version was < −9°. Based on this distribution, version was divided into 3 ranges: < −6°, −7 to −14°, and > −15°. Standard glenoids were used 79% of the time when the version was <−6°. 8° augmented glenoids were used 80% of the time when the version was between −7° and −14°, and 75% of the time when the version was > −15°. In the latter case, 16° augments were used in the other 25%. For inclination in ATSA, the same trends of a bimodal distribution seen for version were less pronounced. A local maxima of plans were focused around zero degrees, with some surgeons being more accepting of superior inclination in ATSA. CONCLUSION. While there was limited consensus on the optimal reconstruction in any one case, there appear to be thresholds of retroversion that favor the use of augmented glenoid components based on frequency of selection. Our data suggests when retroversion exceeds −7°, some degree of augmentation is helpful in achieving the goals of version correction while limiting bone loss through corrective reaming. Longer term clinical outcomes on specific implant positions will help to define true optimal implant placement

INTRODUCTION. 3D preoperative planning software for anatomic total shoulder arthroplasty (ATSA) provides surgeons with increased ability to visualize complex joint relationships and deformities. Interestingly, the advent of such software has seemed to create less of a consensus on the optimal way to plan an ATSA rather than more. In this study, a survey of shoulder specialists from the American Shoulder and Elbow Society (ASES) was conducted to examine thought patterns in current ATSA implant selection and placement. METHODS. 172 ASES members completed an 18-question survey on their thought process for how they select and place an ATSA glenoid implant. Data was collected using a custom online Survey Monkey survey. Surgeon answers were split into two cohorts based on number of arthroplasties performed per year: between 0–75 was considered low volume (LV), and between 75–200+ was considered high volume (HV). Data was analyzed for each cohort to examine differences in thought patterns, implant selection, and implant placement. RESULTS. 70 surgeons were grouped into the LV cohort, and 102 surgeons were grouped into the HV cohort. 46.1% of surgeons in the HV cohort reported using a preoperative planning software for the majority of cases vs. 41.4% in the LV cohort, 48% of surgeons in the HV cohort reported seldom use vs. 24.3% in the LV cohort, and 5.9% of surgeons in the HV cohort reported no use vs. 34.3% in the LV cohort (Figure 1). When questioned on what percentage of ATSA cases do surgeons use augmented glenoid implants, 20.6% in the HV cohort responded never using augments vs. 30% in the LV cohort, 39.2% responded using augments <15% of the time in the HV cohort vs. 34.3% in the LV cohort, 26.5% responded using augments between 15–45% of the time in the HV cohort vs. 28.6% in the LV cohort, and 13.7% responded using augments >45% of the time in the HV cohort vs. 7.2% in the LV cohort (Figure 2). When asked what the maximum allowable residual retroversion for an ATSA glenoid implant is, surgeons answered 0–5° 6.9% of the time in the HV cohort vs. 4.3% in the LV cohort, 6–9° 35.6% of the time in the HV cohort vs. 50% in the LV cohort, 10–12° 34.7% of the time in the HV cohort vs. 32.9% in the LV cohort, 13–15° 10.9% of the time in the HV cohort vs. 8.6% in the LV cohort, and lastly >16° 11.9% of the time in the HV cohort vs. 4.3% in the LV cohort (Figure 3). CONCLUSION. Research suggests ATSA glenoid implants may be less forgiving of malalignment than reverse shoulder glenoid implants, but the contrasting survey results in this study reveal that a consensus in optimal placement has yet to be reached. Interestingly, even though HV use more augmented glenoid components than LV surgeons, HV surgeons are more accepting of residual glenoid component retroversion than LV surgeons. Despite these differences, there is no way to prove the optimal implant selection and placement without long-term clinical outcomes. For any figures or tables, please contact the authors directly

Introduction

The clinical impact of radiolucent glenoid lines is controversial, where the presence of a radiolucent glenoid lines has been suggested to be an indicator of clinical glenoid loosening. The goal of this database analysis is to quantify and compare the pre- and post-operative outcomes of 427 patients who received a primary aTSA with one specific prosthesis and were sorted based upon the radiographic presence of a radiolucent glenoid line at latest clinical followup.

Introduction

Machine learning is a relatively novel method to orthopaedics which can be used to evaluate complex associations and patterns in outcomes and healthcare data. The purpose of this study is to utilize 3 different supervised machine learning algorithms to evaluate outcomes from a multi-center international database of a single shoulder prosthesis to evaluate the accuracy of each model to predict post-operative outcomes of both aTSA and rTSA.

The 2021 Australian Orthopaedic Association National Joint Replacement Registry report indicated that total shoulder replacement using both mid head (TMH) length humeral components and reverse arthroplasty (RTSA) had a lower revision rate than stemmed humeral components in anatomical total shoulder arthroplasty (aTSA) - for all prosthesis types and diagnoses. The aim of this study was to assess the impact of component variables in the various primary total arthroplasty alternatives for osteoarthritis in the shoulder. Data from a large national arthroplasty registry were analysed for the period April 2004 to December 2020. The study population included all primary aTSA, RTSA, and TMH shoulder arthroplasty procedures undertaken for osteoarthritis (OA) using either cross-linked polyethylene (XLPE) or non-cross-linked polyethylene (non XLPE). Due to the previously documented and reported higher revision rate compared to other anatomical total shoulder replacement options, those using a cementless metal backed glenoid components were excluded. The rate of revision was determined by Kaplan-Meir estimates, with comparisons by Cox proportional hazard models. Reasons for revision were also assessed. For a primary diagnosis of OA, aTSA with a cemented XLPE glenoid component had the lowest revision rate with a 12-year cumulative revision rate of 4.7%, compared to aTSA with cemented non-XLPE glenoid component of 8.7%, and RTSA of 6.8%. The revision rate for TMH was lower than aTSA with cemented non-XLPE, but was similar to the other implants at the same length of follow-up. The reason for revision for cemented aTSR was most commonly component loosening, not rotator cuff deficiency. Long stem humeral components matched with XLPE in aTSA achieve a lower revision rate compared to shorter stems, long stems with conventional polyethylene, and RTSA when used to treat shoulder OA. In all these cohorts, loosening, not rotator cuff failure was the most common diagnosis for revision

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

A reverse total shoulder arthroplasty (RSA) is frequently performed in the revision setting. The purpose of this study was to report the clinical outcomes and complication rates following revision RSA (RRSA) stratified according to the primary shoulder procedure undergoing revision, including failed hemiarthroplasty (HA), anatomic total shoulder arthroplasty (TSA), RSA, soft tissue repair (i.e., rotator cuff repair), and open reduction internal fixation (ORIF). A systematic review of the literature was performed using four databases (EMBASE, Medline, SportDISCUS, and Cochrane Controlled Trials Register) between January 1985 and September 2017. The primary outcomes of interest included active range-of-motion (ROM), pain, and functional outcome measures including the American Shoulder and Elbow Surgeons Score (ASES), Simple Shoulder Test (SST), and Constant-Murley (CS) Score. Secondary outcomes included complication rates, such as infection, dislocation, perioperative fracture, base plate failure, neurovascular injury, soft tissue injury, and radiological evidence of scapular notching. Clinical outcome data was assessed for differences between preoperative and postoperative results and complication results were reported as pooled complication rates. Forty-five studies met the inclusion criteria for analysis, which included 1,016 shoulder arthroplasties with a mean follow-up of 45.2 months (range, 31.1 to 57.2 months) (Fig. 1). The mean patient age at revision was 60.2 years (range, 36 to 65.2 years). Overall, RSA as a revision procedure for failed HA revealed favorable outcomes with respect to forward elevation (FE), CS pain, ASES, SST, and CS outcome assessment scores, with mean improvements of 52.5° ± 21.8° (P = < 0 .001), 6.41 ± 4.01 SD (P = 0.031), 20.1 ± 21.5 (P = 0.02), 5.2 ± 8.7 (P = 0.008), and 30.7 ± 9.4 (P = < 0 .001), respectively. RSA performed as a revision procedure for failed TSA demonstrated an improvement in the CS outcome score (33.8 ± 12.4, P = 0.016). RSA performed as a revision procedure for failed soft tissue repair demonstrated significant improvements in FE (60.2° ± 21.2°, P = 0.031) and external rotation (20.8° ± 18°, P = 0.016), respectively. Lastly, RSA performed as a revision procedure for failed ORIF revealed favorable outcomes in FE (61° ± 20.2°, P = 0.031). There were no significant differences noted in RSA performed as a revision procedure for failed RSA, or when performed for a failed TSA, soft tissue repair, and ORIF in any other outcome of interest. Pooled complication rates were found to be highest in failed RSA (10.9%), followed by soft tissue repair (7.1%), HA (6.8%), TSA (5.4%) and ORIF (4.7%). When compared to other revision indications, RRSA for failed HA demonstrated the most favorable outcomes, with significant improvements in ROM, pain, and in several outcome assessments. Complication rates were determined and stratified as per the index procedure undergoing RRSA, patients undergoing revision of a failed RSA were found to have the highest complication rates. With this additional information, orthopaedic surgeons will be better equipped to provide preoperative education regarding the risks, benefits and complication rates to those patients undergoing a RRSA. For any figures or tables, please contact authors directly

Experience has demonstrated in the hip and knee, related to total joint replacement arthroplasty, polymethyl methacrylate cement fixation can provide problems in terms of loosening, fragmentation, particulate wear and ultimate failure. These same problems have been recognised in total shoulder arthroplasty related to cement fixation of the glenoid. While cement fixation of the humeral component has proven much less problematic, there has been a swelling towards avoidance of using cement to secure the humeral component for fear of difficulty if revision is required. Surprisingly, with the high incidence of lucent lines, bone resorption and frank loosening, representing the most common source of failure in total shoulder arthroplasty, cementless fixation of the glenoid has not been, until now, embraced. The advent of reverse total shoulder arthroplasty has demonstrated the ability for secure cementless fixation to provide long-lasting secure implant retention in implants which have inherently higher shear and stress forces passing through the implant/bone interface. In anatomic total shoulder arthroplasty a woven tantalum anchor (Trabecular Metal) has proven to demonstrate secure cementless fixation as well. This presentation will discuss the use of trabecular metal anchored glenoid implants with and without additional screw fixation for anatomic and convertible reverse arthroplasty baseplates. Avoidance of complications with successful long-lasting outcomes requires meticulous surgical attention to detail

Patients over 70 years old have subclinical or impending rotator cuff dysfunction, raising concern about TSA in this population. The purpose of this study is to examine whether reverse total shoulder arthroplasty (RTSA) should be considered for the treatment of glenohumeral osteoarthritis in the presence of an intact rotator cuff (GHOA+IRC in patients older than 70 years of age. Twenty-five elderly (>70 years) patients at least one year status-post RTSA for GHOA+IRC were matched via age, sex, body mass index, smoking status, and whether the procedure involved the dominant extremity with 25 GHOA+IRC patients who received anatomic total shoulder arthroplasty (TSA). Standardised outcome measures, range of motion, and treatment costs were compared between the two groups. Treatment cost was assessed using implant and physical therapy costs as well as reimbursement. Patients who received RTSA for GHO+IRC had significantly lower pre-operative active forward elevation (AFE, 69° vs. 98°, p <0.001) and experienced a greater change in AFE (p=0.01), but had equivalent AFE at final follow-up (140° vs. 142°, p=0.71). Outcomes were otherwise equivalent between groups with no differences. In both those patients who underwent TSA and those that underwent RTSA, significant improvements between pre-operative and final follow-up were seen in all standardised outcome measures and in AFE (p<0.001 in all cases). RTSA provided these outcomes at a cost savings of $2,025 in Medicare reimbursement due to decreased physical therapy costs. In patients over the age of 70 with GHOA+IRC, RTSA provides similar improvement in clinical outcomes to TSA at a reduced cost while avoiding issues related to the potential for subclinical or impending rotator cuff dysfunction

Introduction. Previous hemodynamics studies in shoulder arthroplasty only evaluated Western population and mainly focused on risk factors of transfusion. However, Asians are relatively small, and have higher bleeding risk due to prothrombin-clotting-factor polymorphisms. Therefore, it is not appropriate to apply the results of previously studies directly to Asians. Authors compare different hemodynamics depending on the types of shoulder arthroplasties, and evaluate predictors for transfusion in Asian population. Methods. Total 212 shoulder arthroplasties (26 fracture hemiarthroplasty (fHA), 49 anatomical total shoulder arthroplasty (aTSA), 132 reverse total shoulder arthroplasty (rTSA), and 5 revision surgery) from August 2004 to January 2016 were retrospectively reviewed. Demographics, surgical factors and perioperative hemodynamic factors were compared for each type of arthroplasty. Multivariate regression analysis was conducted to determine predictors for transfusion. Results. Preoperative Hb and Hct level were lower in fHA group (11.9 ± 1.8g/dL, 35.1 ± 5.4%; p < 0.001, 0.001). Total drain output was higher in rTSA and revision (349.1 ± 191.7mL, 408.6 ± 125.8mL; p<0.001, <0.001), however, there was no significant difference of estimated blood loss (p=0.269). There was significant, but very weak correlation between drain output with Hb decrease in postoperative one day (r = 0.192; p = 0.007). However, there were not significant correlation between drain output with Hb decrease after postoperative 2 and 3 days (r = 0.185, 0.001; p = 0.241, 0.997). The overall transfusion rate was 11.3% (24/212); fHA 30.8% (8/26), aTSA 10.2% (5/49), rTSA 7.6% (10/132), revision 20% (1/5). In multivariate regression analysis, lower Hb level of preoperative period and postoperative 1 day were predictors for transfusion (OR = 0.481, 0.499; p = 0.002, 0.017) and cutoff-value were 12.15g/dL and 10.0g/dL, respectively (OR = 7.404, 5.499; p = <0.001, 0.001; Sensitivity=80%, 70%; Specificity=80%, 84%). Conclusion. In Asian, overall transfusion rate after shoulder arthroplasties was 11.3%, varied by type of arthroplasty. Lower Hb level of preoperative period (<12.15g/dL) and postoperative 1 day (<10.0g/dL) were predictors for transfusion. Surgeons should consider different hemodynamics depending on different types of shoulder arthroplasty, and close monitoring of perioperative Hb level is essential to decrease hemorrhage-related complications, because drain output could not represent perioperative hemorrhage

Purpose:. Glenoid loosening persists as a common cause of anatomic total shoulder arthroplasty (TSA) failure. Considering radiographic evidence of loosening as an endpoint, TSA has a reported survivorship of only 51.5% at 10 years. Component loosening may be related to cementation and it is postulated that poor cement penetration and heat-induced necrosis may partially be responsible. There is a growing interest among surgeons to minimize or abandon cement fixation and rely on biologic fixation to the polyethylene for long-term fixation. De Wilde et al. reported promising early clinical and radiographic results using a pegged, all-polyethylene ingrowth glenoid design implanted without cement. The goal of this study was to compare glenoid micromotion in an all-polyethylene, centrally fluted pegged glenoid using 3 cement fixation techniques. Materials and Methods:. Glenoid components (Anchor Peg Glenoid, Depuy Orthopaedics, Warsaw, IN, USA) (Figure 1) were implanted in polyurethane foam testing blocks with 3 different fixation methods (n = 5 per group). Group I glenoids were implanted with interference fit fixation with no added cement. Group II was implanted with a hybrid fixation, where only the peripheral pegs were cemented. Group III glenoids were fully cemented for implantation. Glenoid loosening was characterized according to ASTM Standard F-2028. The glenoid component and a 44 mm humeral head were mounted to a materials testing frame (858 Mini Bionix II, MTS Crop., Eden Prairie, MN, USA) with a 750N applied joint compressive force (Figure 1). A humeral head subluxation displacement of ± 0.5 mm was experimentally calculated as a value that simulates glenoid rim loading that may occur at higher load activities. For characterization of glenoid loosening, the humeral head was cycled 50,000 times along the superior-inferior glenoid axis, simulating approximately 5 years of device service. Glenoid distraction, compression, and superior-inferior glenoid migration were recorded with two differential variable reluctance transducers fixed to the glenoid prosthesis. Results:. All glenoid components completed the 50,000 cycles of humeral head translation successfully. With respect to glenoid distraction (Figure 2), interference fit fixation had significantly greater distraction compared to both hybrid and fully cemented fixation (p < 0.001). Hybrid fixation also displayed significantly higher distraction compared to fully cemented fixation (p < 0.001). In terms of glenoid compression (Figure 2), hybrid cementation had significantly greater compression compared to both interference-fit and fully cemented fixation (p < 0.001). Discussion:. This is the first biomechanics study comparing glenoid micromotion of a centrally fluted, pegged component using 3 different fixation techniques. Of all fixation methods, the fully cemented components displayed the least amount of motion in all parameters. Hybrid fixation exhibited lower distraction, higher compression, and comparable translation compared to interference-fit fixation. Results may indicate the differences in early motion and suggest little to no advantage of peripheral peg cementation over no cement with respect to initial fixation. Future studies are warranted to further evaluate interference-fit fixation as a viable option for implantation of a central fluted, all-polyethylene glenoid component