We compared the rate of revision of two classes of primary anatomic shoulder arthroplasty, stemmed (aTSA) and stemless (sTSA) undertaken with cemented all polyethylene glenoid components.

A large national arthroplasty registry identified two cohort groups for comparison, aTSA and sTSA between 1^st January 2011 and 31^st December 2020. A sub-analysis from 1 January 2017 captured additional patient demographics. The cumulative percentage revision (CPR) was determined using Kaplan-Meier estimates of survivorship and hazard ratios (HR) from Cox proportional hazard models adjusted for age and gender.

Of the 7,533 aTSA procedures, the CPR at 8 years was 5.3% and for 2,567 sTSA procedures was 4.0%. There was no difference in the risk of revision between study groups (p=0.128).

There was an increased risk of revision for aTSA and sTSA undertaken with humeral head sizes <44mm (p=0.006 and p=0.002 respectively). Low mean surgeon volume (MSV) (<10 cases per annum) was a revision risk for aTSA (p=0.033) but not sTSA (p=0.926).

For primary diagnosis osteoarthritis since 2017, low MSV was associated with an increased revision risk for aTSA vs sTSA in the first year (p=0.048). Conversely, low MSV was associated with a decreased revision risk for sTSA in the first 6 months (p<0.001). Predominantly aTSA was revised for loosening (28.8%) and sTSA for instability/dislocation (40.6%).

Revision risk of aTSA and sTSA was associated with humeral head size and mean surgeon volume but not patient characteristics. Inexperienced shoulder arthroplasty surgeons experience lower early revision rates with sTSA in the setting of osteoarthritis. Revision of aTSA and sTSA occurred for differing reasons.

Aims

Controversy about the use of an anatomical total shoulder arthroplasty (aTSA) in young arthritic patients relates to which is the ideal form of fixation for the glenoid component: cemented or cementless. This study aimed to evaluate implant survival of aTSA when used in patients aged < 60 years with primary glenohumeral osteoarthritis (OA), and to compare the survival of cemented all-polyethylene and cementless metal-backed glenoid components.

BACKGROUND. Stability of the glenoid component is essential to ensure successful long-term outcomes following Total shoulder arthroplasty (TSA), and may be improved through better glenoid component design. As such, this study assessed identical all-polyethylene glenoid components stability, having various fixation types, using component micromotion under simulated joint loading in an osteoarthritic patient cohort. METHODS. Five all-polyethylene glenoid component designs were compared (Keel, Central-Finned 4-Peg, Peripheral 4-Peg, Cross-Keel, and Inverted-Y). A cement mantle surrounded each fixation type, except the Central-Finned 4-Peg which was surrounded by bone. The humeral component had a non-conforming radius of curvature. Scapular models of six type A1 osteoarthritic male patients (mean: 61 years old, range: 48 to 76 years old) were assigned heterogeneous bone properties based on CT intensity. Each of the 30 scapula models were truncated and fully constrained on the medial scapular border. The bone/cement interface was fully bonded, and the fixation feature/cement interface was frictionally constrained. A ‘worst case’ load magnitude of 125% BW of a 50th percentile male was used. A purely compressive load was applied to the center of the glenoid component, followed by superior, superior-posterior, posterior, inferior-posterior, and inferior loads. Stability of the glenoid component based solely on the fixation type was determined using the mean and maximum normal (liftoff) and tangential (sliding) micromotion in six regions of the glenoid component. RESULTS. The greatest mean normal micromotion occurred for the Inverted-Y (90 ± 36 μm) in the anterior- inferior region of the component under a posterior-superior directed load. The mean normal micromotions were significantly less for the same region and loading direction in the Peripheral 4-peg (48 ± 16 μm; p < .001) and Central-Finned 4-Peg (35 ± 13 μm; p < .001), but not significantly different for the Keel (78 ± 37 μm; p = .029), or Cross-Keel (82 ± 32 μm; p = .143). The same region and loading direction produced the maximum normal micromotion in the Inverted-Y (109 ± 43 μm), which was significantly greater than the other four components (Peripheral 4-peg, 61 ± 25 μm; p < .001, Keel, 89 ± 36 μm; p < .001, Central-Finned 4-Peg, 47 ± 19 μm; p < .001, and Cross-Keel, 92 ± 37 μm; p = .002). The greatest mean tangential micromotion occurred for the Cross-Keel (100 ± 36 μm) in the posterior-superior region of the glenoid component under a posterior-superior directed load. The mean tangential micromotions for all other components were significantly less (p < .001) for the same region and loading direction (Peripheral 4-peg, 73 ± 19 μm, Keel, 73 ± 22 μm, Central-Finned 4-Peg, 73 ± 26 μm, and Inverted-Y, 83 ± 24 μm). The same region and loading direction for the maximum tangential micromotion was also in the Cross-Keel (146 ± 46 μm), which was significantly greater (p < .001) from the other four components (Peripheral 4-peg, 111 ± 21 μm, Keel, 115 ± 34 μm, Central-Finned 4-Peg, 111 ± 39 μm, and Inverted-Y, 117 ± 34 μm). DISCUSSION. This study addressed the contribution of all-polyethylene glenoid component fixation types on component stability under simulated joint loading. Pegged components were significantly more stable than keeled components. An inverse relationship between normal and tangential micromotion was observed, with the greatest sliding (tangential micromotion) occurring in the direction of the applied load, and the greatest liftoff (normal micromotion) occurring opposite the applied load. This likely occurs due to polyethylene deformation of both the fixation features and the component as a whole

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

Total shoulder arthroplasty (TSA) is an excellent surgical solution for patients with shoulder arthritis, providing good to excellent results in the vast majority of patients. Complications are rare, however, when they occur, can be devastating for both the patient and surgeon. An increasingly recognised complication of TSA is glenoid component failure. In a recent review of nearly 4000 shoulder arthroplasties, symptomatic glenoid component loosening occurs at a rate of 1.2% per year, while asymptomatic radiolucent lines occur at a rate of 7.3% per year. In addition, keeled glenoid components have been found to have an increased incidence of radiolucent lines compared to pegged glenoid components at both short and longer-term follow-up. Further, pegged glenoid components are associated with a lower risk of revision arthroplasty compared to keeled glenoid components. In a separate study of approximately 4600 shoulder arthroplasties, metal-backed glenoid components were found to have significantly lower rates of radiolucent lines, radiographic loosening, and component failure compared to all-polyethylene glenoid components. Despite these findings, however, metal-backed components are significantly more likely to require revision surgery (3:1) compared to all-polyethylene components. For the failed TSA due to glenoid component failure, revision with glenoid reimplantation may be considered, but is associated with a high rate of recurrent glenoid loosening. Alternatively, revision to a reverse shoulder arthroplasty, is feasible, but is technically demanding with high complication and reoperation rates. This paper will discuss the etiology, work-up, and treatment of patients with glenoid component failure following TSA

Aims

To report early (two-year) postoperative findings from a randomized controlled trial (RCT) investigating disease-specific quality of life (QOL), clinical, patient-reported, and radiological outcomes in patients undergoing a total shoulder arthroplasty (TSA) with a second-generation uncemented trabecular metal (TM) glenoid versus a cemented polyethylene glenoid (POLY) component.

Introduction. the aim of this study was to analyse the long-term radiological changes following tsa in order to better understand the mechanisms responsible for loosening. Material and methods. between 1991 and 2003, in 10 European centers, 611 shoulder arthroplasties were performed for primary osteoarthritis using a third generation anatomic prosthesis with a cemented all-polyethylene keeled glenoid component. Full radiographic and clinical follow-up greater than 5 years was available for 518 shoulders. Kaplan-meier survivorship analysis was performed with glenoid revision for loosening and radiological loosening as end points; clinical outcome was assessed with the constant score, patient satisfaction score, subjective shoulder value and range of movement. Results. after a mean follow-up of 103,6 months (61-209 months),the constant score improved significantly(p<0,0001) from 30,1 points pre-operatively to 65,2 points at latest follow-up. the active anterior elevation increased from 91,5 to 138,1 degrees (p<0,0001),and active external rotation increased from 7,9 to 33,2 degrees (p<0,0001). 90,3% of patients were either very satisfied or satisfied with their outcome and the average ssv was 77,1%. radiological loosening was found in 166 cases(32%).three pattern of glenoid component migation were observed in 136 cases: superior tilting (10%), posterior tilting(6,3%), and a subsidence (7,9%) of the glenoid component. different risk factors were statistically associated with the migration of the glenoid component(p<0,001):proximal migration of the humeral head, excessive reaming of the glenoid, type of glenoid preparation for the keel (i.e. curettage technique described by neer in 1972 versus cancellous compaction tecnique described by gazielly in 2003).survivorship with the end-point being glenoid revision for loosening was 99,8% at 5 years,95,9% at 10 years, and 77,5% at 15 years. Conclusion- to reduce risk of loosening of the glenoid component, we recommand consideration of the following: optimization of the design and size of the implant, limit the amount of reaming so as to not sacrifice the subchondral glenoid bone, and prepare the glenoid with cancellous compaction rather than curettage technique

The purpose of the study was to reduce peak cement mantle stresses occurring at the tip of the keel for an all-polyethylene cemented glenoid component using finite element (FE) techniques. Loosening of the glenoid component remains to be one of the most determinant factors in the outcome of total shoulder arthroplasty. Due to the off-centre loading that occurs, there is bending of the glenoid component with high shearing forces. These forces are transmitted to the underlying cement mantle and bone. It has been reported in previous FE studies that high cement mantle stresses occurs at the tip of the keel and at the edges of the cement flange. These stresses at the bone-cement interface can exceed the fatigue life of the cement, therefore initiating crack formation and damage accumulation. This results in loosening of the component and thus failure. A three-dimensional (3D) model of the scapula was developed using CT data. Surfaces of the inner and outer contours of the cortical shell were created within commercially available software, using a threshold algorithm. The glenoid bone geometry was then produced. Material properties for the reconstructed glenoid were taken from literature, using four differing material properties. The articulating surface of the keeled glenoid component was modelled with a 3mm radial mismatch. This was positioned in the glenoid bone with a uniform cement mantle thickness of 2mm. The resulting FE mesh consisted of solid parabolic tetrahedral elements. The effect of varying the angle on the keel of the component in the superior/inferior (S/I) direction was studied with uniform cement mantle thickness. The S/I length of the keel at the lateral end where it meets the back face of the component was maintained (juncture with flange), whilst the S/I length of the keel at the medial end (tip of the keel) was reduced as the change in angle increased. Two load cases were studied, involving a physiological load for 90 degrees of abduction and a central load of same magnitude. It was found that by increasing the angle of the keel, where the S/I length at the tip of the keel was reduced, resulted in lower cement mantle stresses in this area of interest. This can be attributed to it being further away from the stiffer cortical bone where high tensile stresses exist due to inherent bending of the glenoid construct under loading. Therefore by reducing these high cement mantle stresses at the tip of the keel, fatigue failure of the cement mantle could be reduced

Aims

The Mathys Affinis Short is the most frequently used stemless total shoulder prosthesis in the UK. The purpose of this prospective cohort study is to report the survivorship, clinical, and radiological outcomes of the first independent series of the Affinis Short prosthesis.