Clin Orthop Surg.  2017 Jun;9(2):207-212. 10.4055/cios.2017.9.2.207.

The Dimensions of the Scapula Glenoid in Japanese Rotator Cuff Tear Patients

• Shimozono
• Arai R
• Matsuda S

• KMID: 2412290
• DOI: http://doi.org/10.4055/cios.2017.9.2.207

Abstract

BACKGROUND
Reverse total shoulder arthroplasty has become a widely accepted surgical procedure in Japan since the time when the implants were approved for use in 2014. There is a doubt, however, as to whether the implants designed for Western people are suitable for Japanese people, particularly for females of relatively small stature. The purpose of this study was to investigate the glenoid dimension, with special focus on the length after glenoid reaming, in Japanese rotator cuff tear patients.
METHODS
Fifty-six shoulders of 55 patients (35 males and 20 females; mean age, 63.8 years) were studied. Using the three-dimensional computed tomography images of the entire scapula before shoulder surgery, we measured the glenoid height and width, and calculated the correlation between these measurements and the patient's height. Further, we measured the anteroposterior length of the scapular neck at the subchondral bone and the length at 15 mm medial to the subchondral bone, to simulate both the glenoid width after reaming (width of the "˜virtual reamed surface') and the space available for the end of the center post of a standard glenoid baseplate.
RESULTS
The average glenoid height and width were 35.8 mm and 28.1 mm in males and 30.8 mm and 23.4 mm in females, respectively. There was a significant correlation between patient height and glenoid size (glenoid height, r = 0.69; width, r = 0.75; p < 0.01). The mean value of the width of the virtual reamed surface was 27.0 mm in males and 22.5 mm in females. The mean anteroposterior length at 15 mm medial to the subchondral bone was 12.4 mm in males and 9.5 mm in females; the length was shorter than 8 mm in 6 female shoulders.
CONCLUSIONS
There was a significant correlation between patient height and glenoid size. Considering that the common diameter of the commercially available baseplates and their center posts is greater than 25 mm and 8 mm, respectively, these prosthetic parts would be too large, especially for the Japanese female glenoid. Given that the current results of Japanese shoulder dimensions are similar to those of Asian people, "˜Asian size implants' should be developed.

Keyword

Glenoid cavity; Morphology; Asians; Female; Artificial shoulder joint

MeSH Terms

Adult
Aged
Aged, 80 and over
Asian Continental Ancestry Group/*statistics & numerical data
Female
Glenoid Cavity/*anatomy & histology/*diagnostic imaging
Humans
Japan/epidemiology
Male
Middle Aged
Prosthesis Design
Rotator Cuff Injuries/diagnostic imaging/*epidemiology/surgery
*Shoulder Prosthesis/standards/statistics & numerical data
Tomography, X-Ray Computed

Figure

• 

  Fig. 1 Measurement of the size of the glenoid surface. The superoinferior length (height) and anteroposterior length (width) were measured on three-dimensional images.

• 

  Fig. 2 Method of the measurement of the glenoid width. (A) The measurement was performed on the reconstructed axial slice. (B) The optimal slice was created from the whole three-dimensional data. (C) The axial slice was created vertical to the scapula plane. (D) The axial slice included the glenoid center and the medial pole of the scapula.

• 

  Fig. 3 Axial view perpendicular to the scapular plane. The dashed yellow line drawn just beneath the subchondral bone indicates the level of the virtual reamed surface of the glenoid neck. The length of the dashed yellow line just below the subchondral bone was measured as the width of the virtual reamed surface.

• 

  Fig. 4 Measurement of the anteroposterior length of the scapular neck at 15 mm medial to the virtual reamed surface. The length of the orange line was measured.

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