Wear performance of inverted non-conforming bearings in anatomic total shoulder arthroplasty

Background Glenoid component failures still represent the most common complication in total shoulder arthroplasty. These failures depend on several factors, including ultra-high molecular weight polyethylene (UHMWPE) wear. One reason for UHMWPE wear in total shoulder arthroplasty may be the current use of a spherical prosthetic humeral head against a radially mismatched UHMWPE glenoid component, which leads to reduced glenohumeral translations, glenoid edge loading and high translational forces during shoulder motions. The aim of this study was to assess the in vitro wear of an anatomic total shoulder prosthesis with non-spherical non-conforming bearings with inverted conventional materials. Methods The wear of a vitamin E-blended UHMWPE non-spherical humeral head articulating against a non-conforming titanium-niobium nitride (TiNbN)-coated metallic glenoid was tested using a joint simulator. The wear test was performed by applying a constant load of 756 N with angular motions and translations. Results After 2.5 million cycles, the mean wear rate of the humeral head was 0.28 ± standard deviation (SD) 0.45 mg/million cycles. Conclusion The low wear rate of the vitamin E UHMWPE humeral head supports the use of non-spherical non-conforming bearings with inverted conventional materials in anatomic total shoulder arthroplasty.

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Glenoid Component Position Does Not Affect Short-Term Clinical and Radiologic Outcomes in Total Shoulder Arthroplasty

Journal of Clinical Medicine ◽

10.3390/jcm10245773 ◽

2021 ◽

Vol 10 (24) ◽

pp. 5773

Author(s):

Maciej J. K. Simon ◽

Helen Crofts ◽

Treny Sasyniuk ◽

Kayla Johnston ◽

Derek Plausinis ◽

...

Keyword(s):

Shoulder Arthroplasty ◽

Humeral Head ◽

Total Shoulder Arthroplasty ◽

Female Gender ◽

Glenoid Component ◽

Component Position ◽

Short Term ◽

Patient Reported ◽

Patient Reported Measures

Background: Malpositioning of the glenoid component in total shoulder arthroplasty (TSA) remains the primary source of loosening. The purpose of this study is firstly, to quantify postoperative glenoid component position in patients having a TSA and secondly, to explore whether glenoid component radiolucency is associated with glenoid position, clinical outcomes and patient-reported measures in the short-term (two year) follow-up period. Methods: This study was a sub-study of a larger clinical trial that included patients who underwent a TSA and who were randomized into two different glenoid types with a minimum two-year follow-up period. Post-operative radiographic assessments (six weeks and two years) were used to measure glenoid component position (version, inclination, offset) and humeral head centering anterior–posterior (AP) and superior–inferior (SI), and to assess glenoid component radiolucent scoring (modified Lazarus). Pre-operative X-rays were used to measure glenoid version, inclination and Walch classification. Patient-reported measures (PROMs) included the EQ-5D health slider and the Western Ontario Osteoarthritis (WOOS) and American Shoulder and Elbow Surgeons (ASES) score and were captured at baseline and two years postoperative. Clinical outcomes including range of motion and complications were also documented. Statistical analysis included t-tests and regression modeling. Results: Ninety-one patients with an average age of 69.9 ± 6.2 years were included in this study. Glenoid component position improved significantly in version (−19.4 ± 8.6° to −17.7 ± 8.5°; p < 0.045) and inclination (11.5 ± 7.1° to 5.9 ± 6.3°; p < 0.00001) from preoperative to six weeks postoperative. Glenoid component offset in SI and humeral head centering in AP remained unchanged throughout the follow-up. Radiolucency (Lazarus classification) was recorded in 21 cases (17.3%) with a Lazarus score of 1 (15 cases) and 2 (6 cases). The EQ-5D health slider, WOOS and ASES, and ROM confirmed continuous improvements from the preoperative scores to the two-year follow-up (p < 0.05). Regression models showed no correlation between glenoid component radiolucency at two years and the postoperative week six glenoid component position; however, female gender was a significant variable. Conclusion: Glenoid component changes from its original native glenoid were observed following TSA. Glenoid inclination was improved more than version from baseline, and the humeral head remained well-centered in AP and SI at two years. Radiolucency of the glenoid at two years is not negatively associated with PROMs or component position; however, female gender was identified as a significant predictor and warrants further investigation. Complications are not associated with glenoid position or radiolucency, but longer-term follow-up is required.

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In-vitro evaluation of a polyurethane compliant-layer glenoid for use in shoulder arthroplasty

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1243/09544119jeim626 ◽

2009 ◽

Vol 224 (4) ◽

pp. 551-563 ◽

Cited By ~ 2

Author(s):

C Geary ◽

E Jones ◽

D Fitzpatrick ◽

C P Kelly ◽

C Birkinshaw

Keyword(s):

Shoulder Arthroplasty ◽

Friction And Wear ◽

Total Shoulder Arthroplasty ◽

Glenoid Component ◽

Wear Performance ◽

In Vitro Evaluation ◽

Biomimetic Approach ◽

Compliant Layer ◽

Ultra High Molecular Weight

A polyurethane glenoid component has been designed and manufactured as part of a total shoulder arthroplasty (TSA) system based on compliant-layer (CL) technology. Compared with conventional TSA designs, this biomimetic approach offers reduced friction and wear and potentially improved longevity. In-vitro evaluation of the glenoid system has included loosening and stability tests, and wear measurement using a specially constructed wear simulator. The results obtained support the hypothesis that a CL glenoid design may provide improved resistance to dynamic loosening and rim erosion, and demonstrate superior wear performance over a standard ultra-high molecular weight polyethylene design. This study not only confirms the feasibility of a CL glenoid component but also highlights the potential to increase implant longevity, thereby allowing earlier surgical intervention before poor glenoid bone stock and soft tissue compromise the outcome of TSA.

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Effect of glenoid component inclination on its fixation and humeral head subluxation in total shoulder arthroplasty

Clinical Biomechanics ◽

10.1016/j.clinbiomech.2004.07.001 ◽

2004 ◽

Vol 19 (10) ◽

pp. 1000-1008 ◽

Cited By ~ 30

Author(s):

R. Oosterom ◽

P.M. Rozing ◽

H.E.N. Bersee

Keyword(s):

Shoulder Arthroplasty ◽

Humeral Head ◽

Total Shoulder Arthroplasty ◽

Glenoid Component

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In vivo wear of polyethylene glenoid components in total shoulder arthroplasty

e-Polymers ◽

10.1515/epoly.2005.5.1.123 ◽

2005 ◽

Vol 5 (1) ◽

Cited By ~ 3

Author(s):

Wojciech Swieszkowski ◽

Mark Frankle ◽

Harald E. N. Bersee ◽

Krzysztof J. Kurzydlowski

Keyword(s):

Wear Rate ◽

Shoulder Arthroplasty ◽

Total Shoulder Arthroplasty ◽

Laser Scanner ◽

Sem Analysis ◽

Glenoid Component ◽

Wear Depth ◽

Volumetric Wear ◽

Revision Operation

AbstractLoosening of the glenoid component after a total shoulder arthroplasty, leading to pain and the need for a revision operation, accounts for one third of all shoulder replacement complications. It has been shown that glenoid loosening could be a result of osteolysis of periprosthetic bone induced by polymeric wear debris. The aim of this study was to determine the amount and pattern of in vivo wear of polyethylene glenoid components by examining a set of so-called retrievals. Six glenoid components were retrieved and examined (5 all-polyethylene and 1 metal-backed). The average time of functioning of these components in human bodies was 10 years with the shortest time of 7 and longest 14 years. Four components were scanned using a laser scanner. The results of measurements have been used to generate geometrical models of the retrievals using CAD software. These models have been subsequently used to determine the maximum depth and volumetric wear rate for each component. All six retrievals were examined using scanning electron microscopy (SEM). The maximum volumetric wear rate and wear depth for the analyzed retrievals was 30 mm3/year and 0.2 mm/year, respectively. From SEM analysis of the retrievals it was found that at macroscopic level the worn surfaces consist of (a) polished and (b) scratched regions. Intensive wear areas and fine multidirectional scratches were dominant in all retrievals. Random scratches were also observed, most probably due to third body wear (cement particles). In two implants pitting areas and surface micro-cracks have been observed, which most likely result from subsurface fatigue.

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Anatomic Augmented Glenoid Implants for the Management of the B2 Glenoid

Journal of Shoulder and Elbow Arthroplasty ◽

10.1177/2471549219870350 ◽

2019 ◽

Vol 3 ◽

pp. 247154921987035

Author(s):

Lisa GM Friedman ◽

Grant E Garrigues

Keyword(s):

Bone Loss ◽

Shoulder Arthroplasty ◽

Humeral Head ◽

Basic Science ◽

Total Shoulder Arthroplasty ◽

Clinical Results ◽

Glenoid Component ◽

Posterior Subluxation ◽

Component Loosening ◽

Reverse Total Shoulder

The B2 glenoid is defined by Walch et al. as a glenoid that is biconcave with posterior erosion accompanied by posterior humeral head subluxation. This creates unique challenges for the treating orthopedic surgeon. Bone loss, excessive retroversion, and posterior subluxation make anatomic shoulder arthroplasty in this setting fraught with increased complications, including instability, glenoid component loosening, and poor clinical outcomes. Many techniques have been devised to treat the arthritic shoulder with a B2 glenoid, including hemiarthroplasty, total shoulder arthroplasty using eccentric reaming, bone grafting and custom implantation, and reverse total shoulder arthroplasty. In this review, we will focus on anatomic total shoulder arthroplasty using augmented glenoid implants to treat the B2 glenoid. Indications, clinical results, and basic science analyses of augmented anatomic glenoids are also discussed.

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Elliptical heads result in increased glenohumeral translation along with micro-motion of the glenoid component during axial rotation in total shoulder arthroplasty

Archives of Orthopaedic and Trauma Surgery ◽

10.1007/s00402-021-04018-4 ◽

2021 ◽

Author(s):

Lukas N. Muench ◽

Cameron Kia ◽

Matthew Murphey ◽

Elifho Obopilwe ◽

Mark P. Cote ◽

...

Keyword(s):

Internal Rotation ◽

Shoulder Arthroplasty ◽

Humeral Head ◽

External Rotation ◽

Total Shoulder Arthroplasty ◽

Axial Rotation ◽

Glenoid Component ◽

Spherical Design ◽

Inferior Aspect ◽

Micro Motion

Abstract Introduction Elliptical-shaped humeral head prostheses have recently been proposed to reflect a more anatomic shoulder replacement. However, its subsequent effect on micro-motion of the glenoid component is still not understood. Materials and methods Six fresh-frozen, cadaveric shoulders (mean age: 62.7 ± 9.2 years) were used for the study. Each specimen underwent total shoulder arthroplasty using an anatomic stemless implant. At 15°, 30°, 45° and 60° of glenohumeral abduction, 50° of internal and external rotations in the axial plane were alternatingly applied to the humerus with both an elliptical and spherical humeral head design. Glenohumeral translation was assessed by means of a 3-dimensional digitizer. Micro-motion of the glenoid component was evaluated using four high-resolution differential variable reluctance transducer strain gauges, placed at the anterior, posterior, superior, and inferior aspect of the glenoid component. Results The elliptical head design showed significantly more micro-motion in total and at the superior aspect of glenoid component during external rotation at 15° (total: P = 0.004; superior: P = 0.004) and 30° (total: P = 0.045; superior: P = 0.033) of abduction when compared to the spherical design. However, during internal rotation, elliptical and spherical heads showed similar amounts of micro-motion at the glenoid component at all tested abduction angles. When looking at glenohumeral translation, elliptical and spherical heads showed similar anteroposterior and superoinferior translation as well as compound motion during external rotation at all tested abduction angles. During internal rotation, the elliptical design resulted in significantly more anteroposterior translation and compound motion at all abduction angles when compared to the spherical design (P < 0.05). Conclusion In the setting of total shoulder arthroplasty, the elliptical head design demonstrated greater glenohumeral translation and micro-motion at the glenoid component during axial rotation when compared to the spherical design, potentially increasing the risk for glenoid loosening in the long term. Level of evidence Controlled Laboratory Study

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Assessment of glenoid baseplate initial micromotion and fixation strength in reverse total shoulder arthroplasty designs using a direct shear force methodology

Shoulder & Elbow ◽

10.1177/17585732211032945 ◽

2021 ◽

pp. 175857322110329

Author(s):

Therese E Parr ◽

Jennifer K Anderson ◽

Alan M. Marionneaux ◽

John M Tokish ◽

Stefan J Tolan ◽

...

Keyword(s):

Shoulder Arthroplasty ◽

Shear Force ◽

Total Shoulder Arthroplasty ◽

Reverse Total Shoulder Arthroplasty ◽

Fixation Strength ◽

Shoulder Prosthesis ◽

Direct Shear ◽

Device Failure ◽

Glenoid Baseplate ◽

Reverse Total Shoulder

Background In a reverse total shoulder arthroplasty, the altered glenohumeral joint center of rotation subjects the glenoid baseplate to increased shear forces and potential loosening. Methods This study examined glenoid baseplate micromotion and initial fixation strength with the application of direct shear force in a Sawbone model. The reverse total shoulder arthroplasty systems examined were the DJO Reverse® Shoulder Prosthesis, the Exactech Equinoxe® Reverse System, and the Tornier AequalisTM Reverse Shoulder Prosthesis. Specimens were cyclically tested with increasing shear loads until 150 µm of displacement between the implant and glenoid was achieved, and subsequently until failure, classified as either 1 cm of implant/glenoid displacement or fracture. Results The average load withstood for the 150 µm threshold for DJO, Tornier, and Exactech was 460 ± 88 N, 525 ± 100 N, and 585 ± 160 N, respectively. The average total load at device failure for DJO, Tornier, and Exactech was 980 ± 260 N, 1260 ± 120 N, and 1350 ± 230 N, respectively. Discussion The Exactech implant design trended toward requiring more load to induce micromotion at each threshold and to induce device failure, most commonly seen as inferior screw pull out. This study proposes design features that may enhance fixation and suggests little risk of initial micromotion or failure during initial post-operative recovery.

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