Evaluation of abduction range of motion and avoidance of inferior scapular impingement in a reverse shoulder model

doi:10.1016/j.jse.2007.11.010

Journal of Shoulder and Elbow Surgery

Volume 17, Issue 4, July–August 2008, Pages 608-615

https://doi.org/10.1016/j.jse.2007.11.010 Get rights and content

The purpose of this study was to determine the effects of prosthetic design and surgical technique of reverse shoulder implants on total abduction range of motion and impingement on the inferior scapular neck. Custom implants in three glenosphere diameters (30, 36, and 42 mm), with 3 different centers of rotation offsets (0, +5, and +10 mm), were placed into a Sawbones scapula (Pacific Research Laboratories, Vashon, WA) in 3 different positions: superior, center, and inferior glenoid. Humeral sockets were manufactured with a 130°, 150°, and 170° neck-shaft angle. Four independent factors (glenosphere diameter, center of rotation offset, glenosphere position on the glenoid, and humeral neck-shaft angle) were compared with the 2 dependent factors of range of motion and inferior scapular impingement. Center of rotation offset had the largest effect on range of motion, followed by glenosphere position. Neck-shaft angle had the largest effect on inferior scapular impingement, followed by glenosphere position. This information may be useful to the surgeon when deciding on the appropriate reverse implant.

Section snippets

Materials and methods

Reverse shoulder implant components consisted of a ball that was attached to the glenoid (glenosphere) and a humeral socket that was attached to a wooden dowel. These components were manufactured using Delrin (DuPont, Wilmington, DE), which is a wear-resistant, low-friction plastic. The glenospheres were manufactured with 3 diameters (30, 36, and 42 mm) and 3 COR offsets (0 mm or hemispherical, +5 mm, and +10 mm offset from the glenoid), as summarized in Table I. The glenoid components were

Total abduction range of motion

The greatest total abduction ROM was 117.5° (42 mm, +10-mm COR, and inferior, 170°), whereas the least maximum total abduction ROM was 40.2° (30 mm, 0-mm COR, and neutral, 170°; and 30 mm, 0-mm COR, and neutral, 150°; Table II). Maximal abduction was limited by impingement on either the acromion or the superior edge of the glenoid. Significant effects on total glenohumeral abduction ROM were found for all the factors studied (P < .0001). The factor with the greatest effect on total abduction

Discussion

A careful analysis of the outcomes after reverse shoulder replacement reveals variable improvement in shoulder elevation.2, 3, 12 To judge these improvements accurately, isolated glenohumeral motion must be evaluated; however, this information has been largely lacking up to now. Seebauer et al9, 10 conducted the only clinical study to isolate the improvement in glenohumeral elevation after a reverse shoulder implant. On the basis of dynamic fluoroscopic radiographs, they reported that the

References (14)

R.W. Nyffeler et al.
Biomechanical relevance of glenoid component positioning in the reverse Delta III total shoulder prosthesis
J Shoulder Elbow Surg
(2005)
P. Boileau et al.
Grammont reverse prosthesis: design, rationale, and biomechanics
J Shoulder Elbow Surg
(2005)
A. Boulahia et al.
Early results of a reverse design prosthesis in the treatment of arthritis of the shoulder in elderly patients with a large rotator cuff tear
Orthopedics
(2002)
M. Frankle et al.
The Reverse Shoulder Prosthesis for glenohumeral arthritis associated with severe rotator cuff deficiency. A minimum two-year follow-up study of sixty patients
J Bone Joint Surg Am
(2005)
P.M. Grammont et al.
Delta shoulder prosthesis for rotator cuff rupture
Orthopedics
(1993)
M. Harman et al.
Initial glenoid component fixation in “reverse” total shoulder arthroplasty: a biomechanical evaluation
J Shoulder Elbow Surg
(2005)
B. Lucas et al.
Estimation of transverse plane pelvic rotation using a posterior-anterior radiograph
Spine
(2005)

There are more references available in the full text version of this article.

Cited by (182)

Lateralization and distalization shoulder angles do not predict outcomes in reverse shoulder arthroplasty for cuff tear arthropathy
2024, Journal of Shoulder and Elbow Surgery
In reverse shoulder arthroplasty (RSA), there are a plethora of measurements regarding implant lateralization and distalization to optimize the center of rotation. Two specific measurements known as the “lateralization shoulder angle” (LSA) and “distalization shoulder angle” (DSA) have been the recent focus of studies to assess their association with RSA and postoperative function. The aim of this study was to evaluate the prognostic clinical value of the LSA and DSA in a large cohort of patients with cuff tear arthropathy (CTA) who were treated with different RSA systems.
Two local shoulder arthroplasty registries were reviewed for all RSA patients documented to have undergone a radiologic assessment and complete 2-year follow-up examination. The main inclusion criterion was primary RSA in patients with CTA. Patients with either a complete teres minor tear, os acromiale, or acromial stress fracture reported between the time of surgery and the 24-month follow-up were excluded. Five RSA implant systems with 4 neck-shaft angles (NSAs) were assessed. The Constant score, Subjective Shoulder Value, and range of motion at 2 years were correlated with both the LSA and DSA assessed on 6-month anteroposterior radiographs. Linear and parabolic univariable regressions were calculated for both shoulder angles, for each prosthesis system, and for the entire patient cohort.
Between May 2006 and November 2019, there were a total of 630 CTA patients who had undergone primary RSA. Of this large cohort of patients, 270 were treated with the Promos Reverse prosthesis system (NSA, 155°); 44, Aequalis Reversed II (NSA, 155°); 62, Lima SMR Reverse (NSA, 150°); 25, Aequalis Ascend Flex (NSA, 145°); and 229, Univers Revers (NSA, 135°). The mean LSA was 78° (standard deviation [SD], 10°; range, 6°-107°), and the mean DSA was 51° (SD, 10°; range, 7°-91°). The average Constant score at 24 months’ follow-up was 68.1 points (SD, 13 points; range, 13-96 points). Neither the linear nor parabolic regression calculations for the LSA or DSA revealed significant associations with any of the clinical outcomes.
Different patients may achieve different clinical outcomes despite having identical LSA and DSA values. There is no association between angular radiographic measurements and 2-year functional outcomes after RSA.
Measurement of lateralization and distalization in Grammont and onlay reverse total shoulder arthroplasty
2023, Seminars in Arthroplasty JSES
Reverse total shoulder arthroplasty (RTSA) implants allow variation in lateral and distal offset (LO and DO). The aim of this study was to measure, compare, and classify LO and DO and to assess the effects of modular changes using 2 humeral RTSA implants (one Grammont and one onlay-type) paired with a common modular glenoid component.
Three thousand eight hundred sixty virtual RTSA models were created. Measurements of LO and DO between reference points (B—center of the ‘baseplate;’ C—‘glenosphere’ center of rotation; P—pivot point of the ‘insert;’ M—midpoint of the distal surface of the ‘tray’ in the onlay humeral implant or midpoint of the proximal surface of the ‘spacer’ in the Grammont implant; J—junction of humeral stem and ‘tray,’ ‘liner’ or ‘spacer;’ H—distal end of stem) were taken. ‘Glenoid offset’ was distance BP (comprising BC and CP); ‘humeral offset’ was distance PH (comprising PJ, JM, and MH); their sum was the ‘global offset.’
Global LO and DO measurements were 14.9-30.9 mm and 13.1-36.3 mm, for the Grammont implant, and 23.0-52.6 mm and 18.0-42.2 mm for the onlay implant. Glenoid LO and DO measurements were 8.2-17.3 mm and 16.3-25.0 mm for the Grammont implant and 11.6-23.1 mm and 12.8-23.3 mm for the onlay implant. LO and DO did not vary proportionally in either implant type. Baseplate modularity affects distance BC; ‘glenosphere’ modularity affects distance BC, (‘glenosphere’ eccentricity and lateralization) and/or distance CP (‘glenosphere’ diameter). Humeral modularity affects distance PH (stem, ‘insert,’ ‘tray,’ and ‘spacer’ geometry, overall neck shaft angle [NSA]) and distance CP (overall NSA). Overall NSA also dictated the relative amount of humeral LO and DO resulting from other humeral modular changes.
Both Grammont and onlay humeral RTSA implants paired with a common modular glenoid component can be configured to create a large range of LO and DO, but values are typically greater when using the onlay humeral component. This is despite the higher NSA of the Grammont implant which would be expected to result in more DO. The described classification of DO together with LO may be beneficial. Previous classifications of RTSA based on their ‘glenoid’ (distance BP) and ‘humeral’ (distance PH) offsets are misleading. Distance BC should be considered as the measure of ‘glenoid’ and distance CH as the measure of ‘humeral’ offset. The ‘glenosphere’ is best thought of as a ‘nonglenoid, nonhumeral spacer’ that can affect both BC and CH.
Neck shaft angle in reverse shoulder arthroplasty: 135 vs. 145 degrees at minimum 2-year follow-up
2023, Journal of Shoulder and Elbow Surgery
The most common complication with reverse shoulder arthroplasty Grammont based design with a 155° neck shaft angle (NSA) is scapular notching. Scapular notching has been associated with reduced clinical outcomes. Reducing the humeral NSA from 155° has been shown to reduce the incidence of scapular notching however it is unknown whether there is a difference in scapular notching between a 145° and 135° NSA. The purpose of this study was to evaluate the effect of decreasing the NSA on scapular notching rate and postoperative range of motion comparing 145° and 135° NSA stems at minimum 2 yr of follow-up.
Consecutive patients undergoing primary reverse shoulder arthroplasty with a NSA of either 145° or 135° between January 2014 and February 2019 were retrospectively reviewed. Patients were included if they were over the age of 18, had minimum clinical follow-up of 24 mo with true postoperative anteroposterior radiographic view.
One hundred and three patients were included for the final analysis: 73 with a 145° NSA and 30 with a 135° NSA stem. The mean age and mean follow-up were respectively 70.9 yr (range, 52.0-89.0) and 32.1 mo. The overall incidence of scapular notching was 46.6 %. There was a statistically significant difference in scapular notching between the 145° (53.4%) and 135° (30%) NSA groups (P = .028). There was no difference in terms of postoperative Constant–Murley Score (mean, 66.1 vs. 68.2; P = .395), Subjective Shoulder Value (mean, 76.5 vs. 83.1%, P = .167), forward flexion (mean, 140° vs. 142°, P = .704), abduction (mean, 123.2° vs. 121.5°, P = .771), external rotation with the arm at the side (mean, 34.1° vs. 37.3°, P = .341) and internal rotation (mean, 5.3 vs. 5.4 pts P = .336) between the 2 groups.
This is the first study to compare the effect of a 145° vs. 135° NSA on scapular notching rates. The key finding of this study is that scapular notching rate was significantly reduced from 53% to 30% in 135° NSA compared to 145° NSA, after at least 24 mo of follow-up. Our data also show that glenoid lateralization and inferiorization has an influence on scapular notching. We are unable to state that the reduced scapular notching rate was due to a reduction in NSA alone. Despite a lower rate of scapular notching, the 135° NSA group has not shown any significant better clinical and functional outcomes.
Robotic biomechanical evaluation of six different reverse shoulder implants
2023, Seminars in Arthroplasty JSES
The reverse total shoulder arthroplasty is a popular surgical treatment for a degenerative shoulder with a nonfunctional rotator cuff. Currently, more than 36 different brands with small different features are available. This creates choice stress among many surgeons, who no longer know which parameters and surgical factors are important to optimize the placement of the implant.
The first purpose of this pilot study was to compare the passive range of motion (ROM) of 6 different implant designs implanted following the manufacturer’s guidelines. The second goal was to identify the impingements after implantation which determines the maximal ROM. The last goal of the study was to link the different parameters of an implant with the ROM.
Six implant systems were implanted on identical sawbones. The procedure was repeated 3 times on a different sawbone to objectify the surgical repeatability of the procedures. A Stäubli TX-90 robot was used to perform and control the humerus' kinematic movement. An optical tracking system was used to perform the system's calibrations, track the humerus and scapula in space, and compute the center of rotation.
There was a wide ROM in the scapular plane (44.8°-105.5°) while the minimal elevation (adduction) varied between −4.8° and 35.6°. The rotational movements were limited by contact of the superior humeral polyethylene inlay and the inferior scapular neck. The adduction in the coronal and scapular plane was limited by inferior scapular impingement, whereas the maximal abduction was limited either by bony contact between the humerus and acromion or by contact between the humeral polyethylene inlay and the superior glenoid cavity. A bigger radius of the glenosphere resulted in a larger passive humeroscapular ROM (P < .001). A larger Neck-Shaft-Angle results in a better abduction (P < .001) but compromised adduction (P < .001). The localization of the center of rotation has a significant impact on the ROM. The medialized designs have larger abduction and rotational angles (P < .001).
There is a wide variation in the measured glenohumeral ROM between the 6 frequently implanted prostheses. The most important factor to optimize the impingement-free ROM in all types of prostheses is the creation of the prosthetic overhang of the glenosphere to the bone. Too much lateralization of the center of the glenosphere with or without lateralization of the humeral stem can create a subacromial and/or subcoracoidal impingement.
Accuracy of reverse shoulder arthroplasty angle according to the size of the baseplate
2023, Journal of Shoulder and Elbow Surgery
Glenoid inclination must be assessed precisely during preoperative planning for reverse shoulder arthroplasty (RSA) to position the glenoid baseplate correctly. We hypothesized that a more dynamic measurement method would better match the diversity of glenoid heights in the population and the variety of commercialized glenoid baseplates. Our purpose was to describe a new method to measure the RSA angle accounting for the baseplate size.
Computed tomography scans of 50 shoulders that underwent RSA for primary osteoarthritis or cuff tear arthropathy between June 2019 and February 2020 were included (mean age, 76 years). Three variants of the RSA angle were measured: the RSA angle as originally described by Boileau et al, the relative RSA 25 angle (which simulates the implantation of a 25-mm baseplate), and the relative RSA 29 angle (which simulates the implantation of a 29-mm baseplate). Measurements in the 2-dimensional true reformatted scapular plane were made by 3 independent operators.
The mean R-S distance (ie, distance between point R [intersection of supraspinatus fossa line with glenoid surface] and point S [inferior border of glenoid]) was 24.2 ± 4.0 mm. The mean RSA angle was 20.3° ± 8.4°, whereas the mean relative RSA 25 angle was 19.3° ± 7.8° and the mean relative RSA 29 angle was 15.6° ± 7.6°. The mean difference between the RSA angle and the relative RSA 25 angle was 1.0° ± 4.1° (P = .16). The mean difference between the RSA angle and the relative RSA 29 angle was 4.7° ± 3.8° (P < .0001). In half of the shoulders in our series, the difference between the RSA angle and the RSA 29 angle exceeded 5°.
The RSA angle is a reproducible measure of the inclination of the inferior part of the glenoid that is reliable in most cases for glenoid baseplates of 24-25 mm in height. However, surgeons should be aware that the RSA angle may overestimate the superior orientation of the inferior glenoid for baseplates of different sizes or for small- or large-stature patients. In these cases, the relative RSA angle adapted to the size of the baseplate more accurately evaluates the inclination of the inferior glenoid.
Does glenohumeral offset affect clinical outcomes in a lateralized reverse total shoulder arthroplasty?
2023, Journal of Shoulder and Elbow Surgery
Reverse total shoulder arthroplasty (rTSA) exhibits high rates of success and low complication rates. rTSA has undergone numerous design adaptations over recent years, and lateralization of implant components provides theoretical and biomechanical benefits in stability and range of motion (ROM) as well as decreased rates of notching. However, the magnitude of implant lateralization and its effect on these outcomes is less well understood. The purpose of this study was to evaluate how increasing glenohumeral offset affects outcomes after rTSA, specifically in a lateralized humerus + medialized glenoid implant model.
Primary rTSA using a lateralized humeral + medialized glenoid implant model performed at a single academic institution between 2012 and 2018 were retrospectively reviewed. Patient-reported outcome (PRO) parameters and clinical outcomes including ROM were evaluated both pre- and postoperatively. Pre- and postoperative radiographs were analyzed for measurement of glenohumeral offset, defined as the acromial-tuberosity offset (ATO) distance on the anteroposterior radiograph.
A total of 130 rTSAs were included in the analysis, with a mean follow-up of 35 mo. The mean postoperative absolute ATO was 16 mm, and the mean delta ATO (difference from pre- to postoperatively) was 4.6 mm further lateralized. Among all study patients, improvements in all ROM parameters and all PROs were observed from pre- to postoperative assessments. When assessing for the effects of lateralization on these outcomes, multivariate analysis failed to reveal a significant effect from the absolute postoperative ATO or the delta ATO on any outcome parameter.
rTSA using a lateralized humeral + medialized glenoid implant model exhibits excellent clinical outcomes in ROM and PROs. However, the magnitude of lateralization as measured radiographically by the ATO did not significantly affect these outcomes; patients exhibited universally good outcomes irrespective of the degree of offset restoration.

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: This research was supported in part by the Florida Orthopaedic Institute Research Foundation.

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Original articleEvaluation of abduction range of motion and avoidance of inferior scapular impingement in a reverse shoulder model

Section snippets

Materials and methods

Total abduction range of motion

Discussion

J Shoulder Elbow Surg

Grammont reverse prosthesis: design, rationale, and biomechanics

J Shoulder Elbow Surg

Early results of a reverse design prosthesis in the treatment of arthritis of the shoulder in elderly patients with a large rotator cuff tear

Orthopedics

The Reverse Shoulder Prosthesis for glenohumeral arthritis associated with severe rotator cuff deficiency. A minimum two-year follow-up study of sixty patients

J Bone Joint Surg Am

Delta shoulder prosthesis for rotator cuff rupture

Orthopedics

Initial glenoid component fixation in “reverse” total shoulder arthroplasty: a biomechanical evaluation

J Shoulder Elbow Surg

Estimation of transverse plane pelvic rotation using a posterior-anterior radiograph

Spine

Original article
Evaluation of abduction range of motion and avoidance of inferior scapular impingement in a reverse shoulder model