The effects of progressive lateralization of the joint center of rotation of reverse total shoulder implants

Costantini, Oren; Choi, Daniel; Kontaxis, Andreas; Gulotta, Lawrence V.

doi:10.1016/j.jse.2014.11.040

Cited by 75 publications

(55 citation statements)

References 40 publications

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“…The effects of cup depth and GLat are likely due to impingement, while increasing NSA is advantageous for muscle capability. This is supported by several studies that have reported increases in JCFs with increasing GLat, which can be attributed to higher deltoid force production resulting from decreases in elevation muscle moment arms . Therefore, increases in ROM due to increased GLat are not likely a result of increased muscle efficiency.…”

Section: Discussionsupporting

confidence: 70%

“…Previous studies related to ROM of rTSA generally characterize ranges of motions that are contained within a subset of single paths (i.e., abduction, flexion, axial rotation, etc.) . However, conclusions pertaining to implant performance drawn from a subset of investigated motions may be misleading, as it has been shown that differing implant designs maximize different motions .…”

Section: Discussionmentioning

confidence: 99%

“…It should be noted that the geometries of the humeral cup and glenosphere were generic representations of the existing designs. The design parameters that were varied, as well as their values, have been commonly investigated in the previous studies, as they represent a range of commercially available designs …”

Section: Methodsmentioning

confidence: 99%

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Development and Application of a Novel Metric to Characterize Comprehensive Range of Motion of Reverse Total Shoulder Arthroplasty

Elwell

Athwal

Willing

2019

Journal Orthopaedic Research

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Active range of motion (ROM) of reverse total shoulder arthroplasty (rTSA) can be limited by bony impingement, muscle inability, and joint instability. The aim of this study was to develop a novel metric representative of comprehensive ROM of rTSA, which is evaluated in the context of all three factors. It was hypothesized that the metric, termed global circumduction ROM (GC‐ROM), would capture differences resulting from directional changes in rTSA design parameters known to increase ROM. GC‐ROM was calculated for a set of 18 rTSA configurations with humeral polyethylene cup depths of 6 and 8.1 mm, glenosphere lateralization (GLat) distances of 0, 5, and 10 mm, and neck‐shaft angles (NSA) of 135°, 145°, and 155°. For any implant configuration, arm positions were defined by internal/external (IE) rotation angle and two spherical coordinates representing the elevation plane angle and elevation angle. At each IE rotation angle, incremental positions with variable elevation plane and elevation angles were checked for feasibility based on impingement, muscle ability, and risk of instability. Coordinates of feasible positions were mapped to unit spheres and connected to form regions, of which the surface area was calculated to represent allowable circumduction ROM. ROMs were averaged across all IE rotation angles to produce a single metric, GC‐ROM. The results showed that decreasing cup depth and increasing GLat and NSA increased GC‐ROM. In conclusion, a novel metric to characterize comprehensive ROM, evaluated based on several ROM‐limiting factors, was developed as a performance metric through which rTSA designs can be compared. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:880‐887, 2020

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Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

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Development and Application of a Novel Metric to Characterize Comprehensive Range of Motion of Reverse Total Shoulder Arthroplasty

Elwell

Athwal

Willing

2019

Journal Orthopaedic Research

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“…However, this may come at the cost of compromising primary implant stability and long-term survival of rTSA, because lateralization of the COR increases joint contact forces and bending moments at the bone-implant interface of the glenoid (Costantini et al, 2015). The effect of lateralizing the COR on primary mechanical stability (micromotion) of the glenoid-side implant component (the baseplate) has previously been investigated using bone substitute (Harman et al,2005; Virani et al,2008).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the competing relationship between adduction range of motion and baseplate micromotion with lateralization of reverse total shoulder arthroplasty

Elwell

Choi

Willing

2017

Journal of Biomechanics

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Lateralizing the center of rotation (COR) of reverse total shoulder arthroplasty (rTSA) could improve functional outcomes and mitigate scapular notching, a commonly occurring complication of the procedure. However, resulting increases in torque at the bone-implant interface may negatively affect initial fixation of the glenoid-side component, especially if only two fixation screws can be placed. Shoulder-specific finite element (FE) models of four fresh-frozen cadaveric shoulders were constructed. Scapular geometry and material property distributions were derived from CT data. Generic baseplates with two and four fixation screws were virtually implanted, after which superiorly-oriented shear loads, accompanied by a compressive load, were applied incrementally further from the glenoid surface to simulate lateralization of the COR. Relationships between lateralization, adduction range of motion (ROM), the number of fixation screws and micromotion of the baseplate (initial implant fixation) were characterized. Lateralization significantly increases micromotion (p = 0.015) and adduction ROM (p = 0.001). Using two, versus four, baseplate fixation screws significantly increases micromotion (p = 0.008). The effect of lateralization and the number of screws on adduction ROM and baseplate fixation is variable on a shoulder-specific basis. Trade-offs exist between functional outcomes, namely adduction ROM, and initial implant fixation and the negative effect of lateralization on implant fixation is amplified when only two fixation screws are used. The possibility of lateralizing the COR in order to improve functional outcomes of the procedure should be considered on a patient-specific basis accounting for factors such as availability and quality of bone stock.

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“…Several biomechanical studies have investigated the effect of glenosphere lateralization on RSA. The literature has shown that lateralization can increase impingement free ROM, but it can also increase the deltoid force required during abduction, and thus increase joint loading . Biomechanical studies have already studied the effects of SSc repair in RSA and showed how its adducting moment arm increases (post RSA) and acts antagonistic to the deltoid.…”

mentioning

confidence: 99%

The biomechanics of subscapularis repair in reverse shoulder arthroplasty: The effect of lateralization and insertion site

Eno

Kontaxis

Novoa-Boldo

et al. 2019

Journal Orthopaedic Research

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Functional outcomes of subscapularis (SSc) repair following reverse shoulder arthroplasty (RSA) remains controversial. SSc repair in combination with glenosphere lateralization was reported to yield worse clinical outcomes compared with the non‐lateralized glenosphere. The aim of this biomechanical study was to investigate how glenosphere lateralization and different re‐insertion sites can affect the biomechanics of the SSc after RSA. Nine patient‐specific RSA shoulder models were created from patients' computed tomography scans. Moment arms and SSc length were calculated for abduction, forward flexion, and internal rotation in 20° and 90° abduction for three configurations of glenosphere lateralization (standard/+0, +5, and +10 mm) and three SSc repair sites (native, superior, and inferior) and compared with the native shoulder. When compared with the native shoulder, RSA resulted in large adducting SSc moment arms that were antagonistic to the deltoid. Glenosphere lateralization had no effect on SSc moment arms in any motion. However, lateralization increased SSc tension beyond its anatomic length for +5 and +10 mm of lateralization when attached to its native insertion. A superior SSc repair site created the least adductive moment arm as well as the least amount of SSc lengthening. Increased glenosphere lateralization showed a significant increase in the SSc length, which in combination with its adductive moment arm can be antagonistic to deltoid function. However, a superior SSc repair site may help reduce the adductive SSc moment arm and allow for reduced tension on the repair as its length in that location is less than that of the native SSc. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:888‐894, 2020

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The effects of progressive lateralization of the joint center of rotation of reverse total shoulder implants

Cited by 75 publications

References 40 publications

Development and Application of a Novel Metric to Characterize Comprehensive Range of Motion of Reverse Total Shoulder Arthroplasty

Development and Application of a Novel Metric to Characterize Comprehensive Range of Motion of Reverse Total Shoulder Arthroplasty

Quantifying the competing relationship between adduction range of motion and baseplate micromotion with lateralization of reverse total shoulder arthroplasty

The biomechanics of subscapularis repair in reverse shoulder arthroplasty: The effect of lateralization and insertion site

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