The sizing and suitability of nonspherical ellipsoid humeral heads for total shoulder arthroplasty

Spangenberg, Gregory W.; Faber, Kenneth J.; Langohr, G. Daniel G.; Reeves, Jacob M.

doi:10.1016/j.jse.2022.07.014

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…In addition, implant overhang beyond the cortical rim on axillary radiographs was minimized with an elliptical implant, as overhang beyond 10% was seen in 0%, 29%, and 52% of stemless elliptical, stemless spherical, and stemmed spherical implants, respectively. Consistent with Spangenberg et al, 19 elliptical implants were less likely to be oversized, potentially reducing risk of stiffness and late rotator cuff failure.…”

Section: Clinical and Radiographic Outcomessupporting

confidence: 77%

“…17 Some authors have proposed that elliptical implants that more closely match the cut surface of the humerus and allow easier judgement of head sizing intraoperatively. 18,19 Recently, Spangenberg et al 19 compared how accurately spherical and elliptical implants can provide coverage of the osteotomy site after humeral head resection. The authors performed a humeral head resection using a cutting guide on eight paired cadaveric humeri, and the cortical boundary of the resection plane was digitized.…”

Section: Anatomic Basis For Designmentioning

confidence: 99%

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Elliptical Humeral Head Implants in Anatomic Total Shoulder Arthroplasty

Cohn

Austin

Williams

et al. 2023

J Am Acad Orthop Surg

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Humeral implants for anatomic total shoulder arthroplasty and hemiarthroplasty have typically used spherical humeral heads that have a uniform diameter and radius of curvature. However, the native humeral head has a more elliptical morphology, which has spurred interest in nonspherical implant designs. Cadaveric studies indicate that the native humeral head diameter is 10% longer in the superior-inferior plane than the anterior‐posterior plane and has a radius of curvature that is approximately 8% greater. An elliptical implant that more closely replicates native anatomy may allow for more accurate coverage of the humeral resection surface with less implant overhang and risk of overstuffing. Biomechanical evidence suggests that an elliptical implant yields glenohumeral kinematics that mimic the native joint, and early clinical results are promising. As clinical research continues to emerge, it will become clearer whether encouraging cadaveric, biomechanical, and early clinical data translates to meaningful sustained improvements in patient outcomes.

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Section: Clinical and Radiographic Outcomessupporting

confidence: 77%

Section: Anatomic Basis For Designmentioning

confidence: 99%

Elliptical Humeral Head Implants in Anatomic Total Shoulder Arthroplasty

Cohn

Austin

Williams

et al. 2023

J Am Acad Orthop Surg

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“…Accordingly, biomechanical investigations have shown that elliptical head implants more accurately restored native shoulder kinematics in terms of glenohumeral translation and rotational range of motion [13][14][15]. Further, a joint replacement using elliptical heads was found to provide greater total resection and cortical coverage than implants with a spherical shape, while avoiding excessive overhang [16].…”

Section: Introductionmentioning

confidence: 99%

Contact Mechanics of Elliptical and Spherical Head Implants during Axial Rotation in Anatomic Total Shoulder Arthroplasty: A Biomechanical Comparison

Muench

Slater

Archambault

et al. 2023

JCM

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Background: Elliptical humeral head implants have been proposed to result in more anatomic kinematics following total shoulder arthroplasty (aTSA). The purpose of this study was to compare glenohumeral contact mechanics during axial rotation using spherical and elliptical humeral head implants in the setting of aTSA. Methods: Seven fresh-frozen cadaveric shoulders were utilized for biomechanical testing in neutral (NR), internal (IR), and external (ER) rotation at various levels of abduction (0°, 15°, 30°, 45°, 60°) with lines of pull along each of the rotator cuff muscles. Each specimen underwent the following three conditions: (1) native, and TSA using (2) an elliptical and (3) spherical humeral head implant. Glenohumeral contact mechanics, including contact pressure (CP; kPa), peak contact pressure (PCP; kPa), and contact area (CA; mm2), were measured in neutral rotation as well as external and internal rotation using a pressure mapping sensor. Results: Elliptical head implants showed a significantly lower PCP in ER compared to spherical implants at 0° (Δ−712.0 kPa; p = 0.034), 15° (Δ−894.9 kPa; p = 0.004), 30° (Δ−897.7 kPa; p = 0.004), and 45° (Δ−796.9 kPa; p = 0.010) of abduction, while no significant difference was observed in ER at 60° of abduction or at all angles in NR and IR. Both implant designs had similar CA in NR, ER, and IR at all tested angles of abduction (p > 0.05, respectively). Conclusions: In the setting of aTSA, elliptical heads showed significantly lower PCP during ER at 0° to 45° of abduction, when compared to spherical head implants. However, in NR and IR, PCP was similar between implant designs. Both designs showed similar CA during NR, ER, and IR at all abduction angles. Level of Evidence: basic science; controlled laboratory study.

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