Scholarly article on topic 'Are the Current Size Options of Glenoid Baseplates for Reverse Shoulder Arthroplasty Sufficient for our Local Population?'

Are the Current Size Options of Glenoid Baseplates for Reverse Shoulder Arthroplasty Sufficient for our Local Population? Academic research paper on "Earth and related environmental sciences"

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Abstract of research paper on Earth and related environmental sciences, author of scientific article — Yim Ling Amy Cheung, Wai Hung Chester Lie, Hung Lit Chow, Wai Lam Chan, Kwun Hung Kevin Wong, et al.

Abstract Background/Purpose Reverse shoulder arthroplasty (RSA) is an effective treatment for patients who suffer from shoulder pain and dysfunction associated with a variety of shoulder pathologies including severe rotator cuff deficiency with or without glenohumeral arthritis. It has been widely used in European countries and the United States and is now gaining popularity in Asia, including Hong Kong. However, there are only limited size options available for glenoid baseplates, with 25 mm being the smallest size in some commonly used systems. The aim of our study is to perform computerized tomography (CT) measurements of the glenoid dimension in the Chinese population and to see if the current glenoid baseplate component size option is sufficient for our local population. Methods A total of 70 CT scans of shoulder regions were analysed. Measurements included maximum superoinferior height and the anteroposterior height. Results The glenoid dimensions were smaller compared to those from previous studies in Caucasian counterparts. Some 41% of female glenoids had widths measuring < 25 mm (25 mm being the smallest size available in some commonly used RSA systems). Conclusion Although there are only limited size options available for the glenoid baseplate in RSA, from our data, it should be able to cover most patients in our local population. However, surgeons should exercise special care when contemplating performing reverse shoulder replacement for small size females in our local population.

Academic research paper on topic "Are the Current Size Options of Glenoid Baseplates for Reverse Shoulder Arthroplasty Sufficient for our Local Population?"

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Journal of Orthopaedics, Trauma and Rehabilitation

Journal homepages: www.e-jotr.com & www.ejotr.org

Research Study

Are the Current Size Options of Glenoid Baseplates for Reverse Shoulder Arthroplasty Sufficient for our Local Population? StfiliAUBflftffiiSSfififtft^^I««3 ftAP^il?

CrossMark

Cheung Yim Ling Amy a, Lie Wai Hung Chester b' , Chow Hung Litc, Chan Wai Lam Wong Kwun Hung Kevin d, Woo Siu Bong d, Wong Wing Cheung d

a Department of Orthopaedics and Traumatology, Queen Mary Hospital, Hong Kong b Congruence Orthopaedics and Rehabilitation Centre, Hong Kong c Department of Diagnostic Radiology, Kwong Wah Hospital, Hong Kong d Department of Orthopaedics and Traumatology, Kwong Wah Hospital, Hong Kong

ARTICLE INFO

Article history: Received 29 July 2015 Received in revised form 22 November 2015 Accepted 24 November 2015

Keywords: Chinese

glenoid baseplate

reverse shoulder arthroplasty

ABSTRACT

Background/Purpose: Reverse shoulder arthroplasty (RSA) is an effective treatment for patients who suffer from shoulder pain and dysfunction associated with a variety of shoulder pathologies including severe rotator cuff deficiency with or without glenohumeral arthritis. It has been widely used in European countries and the United States and is now gaining popularity in Asia, including Hong Kong. However, there are only limited size options available for glenoid baseplates, with 25 mm being the smallest size in some commonly used systems. The aim of our study is to perform computerized tomography (CT) measurements of the glenoid dimension in the Chinese population and to see if the current glenoid baseplate component size option is sufficient for our local population. Methods: A total of 70 CT scans of shoulder regions were analysed. Measurements included maximum superoinferior height and the anteroposterior height.

Results: The glenoid dimensions were smaller compared to those from previous studies in Caucasian counterparts. Some 41% of female glenoids had widths measuring < 25 mm (25 mm being the smallest size available in some commonly used RSA systems).

Conclusion: Although there are only limited size options available for the glenoid baseplate in RSA, from our data, it should be able to cover most patients in our local population. However, surgeons should exercise special care when contemplating performing reverse shoulder replacement for small size females in our local population.

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* Corresponding author. E-mail: chesterliewh@gmail.com.

http://dx.doi.org/10.1016/jootr.2015.11.002

2210-4917/Copyright © 2016, The Hong Kong Orthopaedic Association and the Hong Kong College of Orthopaedic Surgeons. Published by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Introduction

Reverse shoulder arthroplasty (RSA; Figures 1 and 2) was originally designed for use in rotator cuff arthropathy and has been used with success in this condition.1 It was designed to transfer the centre of rotation of the humerus medially and to lengthen the humerus. This would result in increased tension of the deltoid muscle and allow for compression between the humeral component and the glenoid component and thus, stabilize the prosthetic joint and lead to a more efficient deltoid lever arm.2

The indications for RSA have now expanded beyond rotator cuff arthropathy and it has been used with success in primary osteo-arthritis with rotator cuff compromise (5—10% of patients with primary osteoarthritis of the shoulder have an associated rotator cuff tear3,4) or glenoid bone loss,5 and varying degrees of success in fractures, rheumatoid arthritis, revision arthroplasty, infection, and tumours.

RSA is gaining popularity in Asia, including Hong Kong, for a variety of shoulder pathologies including severe rotator cuff deficiency, especially for those with glenohumeral arthritis and four part proximal humerus fractures in the elderly.

Unfortunately, current reverse shoulder replacements have limited glenoid baseplate (Figure 3) size options. For example, the Aequalis-Reversed II system (Tornier N.V., Amsterdam, Netherlands) only has two sizing options of 25 mm and 29 mm and the Delta Xtend system (DePuy Synthes, West Chester, PA, USA) only has one baseplate option of 27 mm.

Difficulty in the insertion of the glenoid baseplate in smaller sized glenoids in Korean patients has been reported,6 and this has attributed to the phenomenon where smallest size implant actually covers the entire face of the glenoid with resultant difficulty in achieving stable screw insertion.

Proper sizing in RSA is essential as the initial rigid fixation of the glenoid baseplate is dependent on placement of the screws and adequate glenoid bone stock7 with resultant sufficient bone-implant contact. Improper sizing would result in insufficient bone-implant contact and screw fixation, especially of the anterior

and posterior holes of the baseplate, and this may result in glenoid loosening and decreased longevity of the RSA.8

The width of the glenoid cavity would be the more significant, limiting dimension when choosing glenoid baseplate sizes, since glenoid height is always the larger of the two measurements.

As most of these reverse shoulder replacement systems were designed with the Caucasian population in mind, coupled with the painful experience of our Korean counterparts, we pose the question: would such limited size options be sufficient to cater for the glenoid sizes of our local Chinese population?

There is a paucity of data available about the size of the glenoid in the Chinese population. There is one prior study quantifying the size of the glenoid in the Chinese population,9 performed in a healthy, younger population (average age, 39.6 years).

As the age at which patients develop shoulder arthritis and of those that undergo shoulder arthroplasty is typically beyond the 5th—6th decade of life, it would be more appropriate to quantify the size of the glenoid in an older population.

The results of this study may have a bearing on the development of glenoid components for reversed shoulder replacement to cater for the glenoid dimensions of the Chinese population.

Methods

A total of 80 computerized tomography (CT) scans of the glenoid (including routine CT thorax scans and CT shoulder scans) were performed at our centre from January 2014 to April 2014 and were reviewed by two radiologists. Image analysis was performed using the AW Workstation by General Electric (Fairfield, CT, USA).

Patients over the age of 50 years were included in our study and patients under the age of 50 years were excluded from the study. Seventy Chinese patients (46 men; 24 women) with a mean age of 68.4 years were included in the study. Ten patients were excluded as they were younger than 50 years.

These CT images underwent sagittal oblique reformatting along the articular surface of the glenoid and were then analysed once. Maximal superoinferior height, which was defined as the distance

Figure 1. Postoperative radiograph of a patient who underwent reverse shoulder arthroplasty.

Figure 2. Postoperative clinical photograph of a patient who underwent right reverse shoulder arthroplasty showing good abduction range.

Figure 4. The dimensions of measurement.

assess for any difference between the arthritic and nonarthritic glenoids. Statistical significance was defined as p < 0.05.

Results

between the most superior and inferior points of the glenoid contour, was measured (Figure 4). Measurement of the maximal anteroposterior width of the glenoid, defined as the distance between the most anterior and posterior points of the glenoid contour, was also done. The degree of osteoarthritic change was also assessed.

Statistical analysis was performed using SPSS version 22 (SPSS Inc., Chicago, IL, USA). Student two tailed t test was used to analyse the difference between male and female measurements and to

Figure 3. Diagram showing insertion of a glenoid baseplate.

Sixty-three of the 70 glenoids measured in our study showed evidence of arthritis. Seven glenoids did not show evidence of arthritis.

The mean height of male and female combined arthritic gle-noids was 37.4 mm [standard deviation (SD) 4.1] and the mean width was 28.6 mm (SD 3.6). Glenoid measurements were larger in men (mean height, 30.2 mm; mean width, 39.1 mm) than in women (mean height, 25.8 mm; mean width, 34.4 mm; Table 1 and Figure 5).

Mean height and width of the arthritic glenoids was greater than the values in normal glenoids. However, this observed difference in the height (p = 0.45) and the width (p = 0.637) between the arthritic and nonarthritic groups was not found to be statistically significant.

Glenoid dimensions were also observed to increase with the degree of osteoarthritis (Table 2 and Figure 6). However, these differences were not found to be statistically significant.

Discussion

To our knowledge, this study is the first to include the investigation of the dimensions of the arthritic glenoid in the Chinese population.

A prior study by Wang et al9 in 2009 on healthy Chinese patients with nonarthritic glenoids showed that the general size of Chinese glenoids were generally on the smaller end of the spectrum compared to Caucasian and Black counterparts. The mean width and height measurements were larger for our patients with arthritic glenoids compared to the dimensions for these healthy Chinese patients with nonarthritic glenoids, and this may reflect the general trend of enlargement in arthritic glenoids likely due to incorporation of peripheral osteophytes.

Table 1

Glenoid dimensions amongst patients of different sexes with or without evidence of arthritis

Type of glenoid (no. of patients) Average width (mm) Range (mm) SD Average height (mm) (standard deviation) Range (mm) SD

Male, normal (6) 30.5 26.6-33.5 2.6 37.2 33-40.5 3

Male, arthritic (40) 30.2 23.1-25.2 2.8 39.1 32.2-48 3.5

Female, normal (1) 22.3 29.7

Female, arthritic (23) 25.8 21.9- 32.1 3 34.4 29.0-44.2 3.4

Combined, normal (7) 29.3 22.3- 33.5 3.9 36.1 29.7-40.5 4

Combined, arthritic (63) 28.6 21.9-35.2 3.6 37.4 29-48 4.1

SD = standard deviation.

This difference in height and width of the glenoid between males and females was also statistically significant with a p value < 0.001.

Arthritic glenoid width distribution, male & female

21-23 23-25 25-27 27-29 29-31 31-33 33-35 35-37

Size (mm)

Figure 5. Graph showing the distribution of the glenoid sizes amongst the patients in our study.

Table 2

Glenoid dimensions for patients of different sexes with varying degrees of severity of osteoarthritis

Sex, degree of osteoarthritis Average width (mm) Range (mm) SD Average height (mm) Range (mm) SD

Male, mild 29.7 23.1-34.6 2.8 37.3 32.2-44.5 2.9

Male, moderate 30.6 26.2-35.2 2.9 40.9 35-48 3

Male, severe 32.2 28.6-34.2 3.1 42.2 39.5-46.1 3.4

Female, mild 24.4 21.9-27.3 1.7 33.1 29.0-36.0 2.5

Female, moderate 27.5 22.3-31.2 3.2 35.7 31.4-39.4 2.4

Female, severe 30.4 28.6-32.1 2.5 39 33.8-44.2 7.4

Combined, mild 27.6 21.9-34.6 3.6 35.7 29.9-44.5 3.4

Combined, moderate 29.6 22.3-35.2 3.3 39.9 31.4-48 3.7

Combined, severe 31.5 28.6-34.2 2.7 40.9 33.8-46.1 4.8

SD = standard deviation.

Although we observed a difference in the means for height and width between our patients with evidence of glenohumeral arthritis, this difference was not found to be statistically significant.

The results also indicated that there was an increase in size of glenoid dimensions with increasing severity of osteoarthritis, which again reflects the increasing amount of incorporation of peripheral osteophytes into the glenoid cavity. However, whether these peripheral osteophytes actually serve as a suitable support surface for implants is unclear, and there is a lack of information available in the literature regarding this issue.

Prior studies into glenoid dimensions showed that there were significant differences in the size of glenoids in males and females.10 Our results also echoed these findings with statistically

significant differences in the size between male and female arthritic glenoids noted.

The height and width of the arthritic glenoids measured in our study were smaller than those measured of a primarily Caucasian based population of arthritic glenoids by Walch et al11 (Tables 3 and 4).

As the width of the glenoid cavity is always less than its height, it is the limiting dimension when choosing the glenoid baseplate size.

It should be highlighted that in our female patients 41.7% (10/24 females) had a glenoid width which measured < 25 mm with the size of the smallest glenoid measured being 22 mm. With limitations in the glenoid baseplate options for some commonly used RSA systems, for example, 25 mm being the smallest size available for

Male & female combined

Nil Mild Moderate Severe

Severity of osteoarthritis

Figure 6. Graph illustrating the relationship between glenoid size (height and width) and severity of osteoarthritis.

Table 3

Comparison of the mean glenoid width for our study and the study conducted by Walch et al11

Male & female combined width Female glenoid width Male glenoid width

Chinese (Our study) Caucasian (Walch et al11) 28.6 29.1 25.8 27.2 30.2 32.5

Table 4 Comparison of the mean glenoid height for our study and the study conducted by Walch et al11

Male & female combined average height Female average glenoid height Male average glenoid height

Chinese (Our study) Caucasian (Walch et al11) 37.4 40.25 34.4 37.77 39.1 44.82

the Aequalis-Reversed II system (Tornier N.V.) and 27 mm for the Delta Xtend system (DePuy Synthes) in which only one size of glenoid baseplate is available, sizing issues may be of concern for a substantial proportion of females in our Chinese population, and intraoperative difficulties in insertion of the glenoid baseplate, such as that encountered by our Korean colleagues, may be anticipated.

By contrast, only two of the 40 male patients (5%) with evidence of glenoid arthritis measured < 25 mm in width.

This may serve as a point of reference in the development of glenoid implants which are more catered for the sizing needs of the Chinese population.

This should also alert the surgeon to exercise special caution when contemplating performing reverse shoulder replacement for small size females in our population when this sizing issue may be encountered.

Conclusion

This study found that for reverse shoulder replacement, a significant proportion of the Chinese female population have a glenoid

size that may not be able to be covered by the sizes currently available for some commonly used reverse shoulder replacement systems.

Our results provide a guide for future design of the glenoid component which is more suitable for the Chinese population and should alert the surgeon to exercise special care when contemplating performing reverse shoulder replacement for small size females and males.

Conflicts of interest

The authors hereby declare that they have no conflicts of interest.

Funding/support

No funding or financial support is received for this study. References

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