File
Kumashiro K1, Takayama K2, Kitamoto K1, Yamada S2
1Kurashiki Central Hospital, Department of Rehabilitation, Kurashiki, Japan, 2Kurashiki Central Hospital, Department of Orthopaedic Surgery, Shoulder Center, Kurashiki, Japan
Background: Reverse shoulder arthroplasty (RSA) has been reported to be a successful surgical option. However, the functional recovery of internal rotation (IR) after RSA is poor. The poor IR after RSA reduces belt-tying movement.
Purpose: The purpose of this study was to evaluate and characterize the influence of RSA on scapulothoracic motion during belt-tying movement.
Methods: The subjects were 12 patients postoperative more than 6 months after RSA. The subjects firstly placed their hands on their femurs, and then moved their thumb to the greater trochanter, buttocks, L5, and Th12. The scapula downward rotation (DR), anterior tilt, and retraction/protraction were measured at each of the above positions. The measurement was performed on both the operated/non-operated sides. For DR, the digital inclinometer was aligned along the scapular spine, and the angle relative to the horizontal plane was measured in units of 0.1°. For the anterior tilt, the digital inclinometer was placed perpendicular to the medial part of the infraspinatus fossa, and the angle formed by the line drawn perpendicular to the body surface area of the infraspinatus fossa for each position was measured in units of 0.1°. Retraction/protraction was calculated by the tape measure to determine the linear distance from the posterior angle of the acromion to the spinous process at the same level. In the statistical analysis, two-way analysis of variance was performed based on the measured side and measured position as factors.
Results: There was no interaction in either scapula DR, anterior tilt, or retraction/protraction. DR on the operated side increased significantly at L5 (11.7±12.0°) and Th12 (18.3±12.4°) compared with the greater trochanter (1.0±6.9°), while DR on the non-operated side was not significantly different between the measured positions. Anterior tilt on the operated side was significantly increased in the greater trochanter (32.5±10.0°), buttocks (35.2±9.5°), L5 (37.3±9.2°) and Th12 (40.7±12.0°) compared with the femur (26.0±6.9°). Instead, anterior tilt on the non-operated side was significantly increased in the buttocks (32.6±5.4°), L5 (36.3±6.0°) and Th12 (36.0±6.2°) compared with the femur (26.9±7.0°), but not significantly different between the greater trochanter (30.8±9.3°) and the femur. Although there was no significant difference in retraction/protraction, retraction on the operated side tended to be larger than retraction on the non-operated side.
Conclusion(s): DR on the operated side, the range of motion from the femur to Th12 reached about 20°. In normal shoulders, scapulothoracic DR during belt-tying movement has been reported to occur within a range of approximately 15°, suggesting that DR is greater in RSA than in normal shoulders during belt-tying movement. Anterior tilt increased from the start of belt-tying movement. It has been reported that the scapulothoracic motion in normal shoulders during belt-tying movement occurs behind the body, and movement in front of the body is mainly IR of the glenohumeral joint. A significant increase in anterior tilt between the femur and greater trochanter, which is in front of the body, is considered as a compensation for the reduced glenohumeral joint IR by RSA.
Implications: It was suggested that focus on the scapulothoracic motion is important in the belt-tying movement after RSA.
Keywords: reverse shoulder arthroplasty, belt-tying movement, scapulothoracic motion
Funding acknowledgements: No specially-occurring costs were incurred through the implementation of the study.
Purpose: The purpose of this study was to evaluate and characterize the influence of RSA on scapulothoracic motion during belt-tying movement.
Methods: The subjects were 12 patients postoperative more than 6 months after RSA. The subjects firstly placed their hands on their femurs, and then moved their thumb to the greater trochanter, buttocks, L5, and Th12. The scapula downward rotation (DR), anterior tilt, and retraction/protraction were measured at each of the above positions. The measurement was performed on both the operated/non-operated sides. For DR, the digital inclinometer was aligned along the scapular spine, and the angle relative to the horizontal plane was measured in units of 0.1°. For the anterior tilt, the digital inclinometer was placed perpendicular to the medial part of the infraspinatus fossa, and the angle formed by the line drawn perpendicular to the body surface area of the infraspinatus fossa for each position was measured in units of 0.1°. Retraction/protraction was calculated by the tape measure to determine the linear distance from the posterior angle of the acromion to the spinous process at the same level. In the statistical analysis, two-way analysis of variance was performed based on the measured side and measured position as factors.
Results: There was no interaction in either scapula DR, anterior tilt, or retraction/protraction. DR on the operated side increased significantly at L5 (11.7±12.0°) and Th12 (18.3±12.4°) compared with the greater trochanter (1.0±6.9°), while DR on the non-operated side was not significantly different between the measured positions. Anterior tilt on the operated side was significantly increased in the greater trochanter (32.5±10.0°), buttocks (35.2±9.5°), L5 (37.3±9.2°) and Th12 (40.7±12.0°) compared with the femur (26.0±6.9°). Instead, anterior tilt on the non-operated side was significantly increased in the buttocks (32.6±5.4°), L5 (36.3±6.0°) and Th12 (36.0±6.2°) compared with the femur (26.9±7.0°), but not significantly different between the greater trochanter (30.8±9.3°) and the femur. Although there was no significant difference in retraction/protraction, retraction on the operated side tended to be larger than retraction on the non-operated side.
Conclusion(s): DR on the operated side, the range of motion from the femur to Th12 reached about 20°. In normal shoulders, scapulothoracic DR during belt-tying movement has been reported to occur within a range of approximately 15°, suggesting that DR is greater in RSA than in normal shoulders during belt-tying movement. Anterior tilt increased from the start of belt-tying movement. It has been reported that the scapulothoracic motion in normal shoulders during belt-tying movement occurs behind the body, and movement in front of the body is mainly IR of the glenohumeral joint. A significant increase in anterior tilt between the femur and greater trochanter, which is in front of the body, is considered as a compensation for the reduced glenohumeral joint IR by RSA.
Implications: It was suggested that focus on the scapulothoracic motion is important in the belt-tying movement after RSA.
Keywords: reverse shoulder arthroplasty, belt-tying movement, scapulothoracic motion
Funding acknowledgements: No specially-occurring costs were incurred through the implementation of the study.
Topic: Orthopaedics; Musculoskeletal: upper limb; Older people
Ethics approval required: Yes
Institution: Kurashiki Central Hospital
Ethics committee: Clinical Research Review Committee
Ethics number: Clinical research application No. 2127
All authors, affiliations and abstracts have been published as submitted.
