Defining Two Components of Shoulder Imbalance: Clavicle Tilt and Trapezial Prominence.
1Department of Orthopedic Surgery, Faculty of Medicine, the University of Tokyo, Tokyo, Japan 2Department of Orthopedic Surgery, Rady Children's Hospital and Health Center, San Diego, California.Spine (Impact Factor: 2.3). 08/2012; 37(24). DOI: 10.1097/BRS.0b013e31826e2bbb
Study Design. Single center; prospective case series.Objective. To examine two features of shoulder asymmetry (Clavicle Tilt and Trapezial Prominence) and their correlation to radiographic parameters.Summary of Background Data. Shoulder imbalance is one of the more notable aspects of clinical deformity due to scoliosis. However, a discrepancy between radiographic and clinical shoulder balance in adolescent idiopathic scoliosis (AIS) patients has been reported.Methods. A consecutive series of 113 pre-operative right main thoracic Lenke 1 and 2 AIS curves were included. Clavicle angle (tilt), trapezial angle, and ratio of left to right trapezial area were measured on clinical photos. These were correlated with radiographic measurements of T1 tilt, first rib angle, curve magnitudes, and thoracic and lumbar apical translation to C7 plumb line and CSVL.Results. The average age was 14.1yrs. There were 82 Lenke 1 and 31 Lenke 2 curves with an average thoracic Cobb of 52.1°. The clinical clavicle angle ranged from -10.6 to +5.2° ("+" defined as high on the left) and had modest correlation with T1 tilt, thoracic curve size, and thoracic apical deviation (r value, 0.417, 0.437, and 0.408). Medial shoulder trapezial prominence as by the trapezial angle (range: -16.7 to +9.9) and trapezial area ratio (natural log of ratio range; -1.15 to +0.80) correlated well with the radiographic measurements of T1 tilt, first rib angle, and upper thoracic curve size (trapezial angle: 0.713, 0.679, and 0.686; trapezial area ratio: 0.597, 0.595, and 0.653, respectively).Conclusion. Our analysis suggests there are two distinct regions (lateral and medial) of shoulder height asymmetry. Medial differences reflected in trapezial prominence relate to deformity created by upward tilted proximal ribs and T1 tilt. Lateral differences in shoulder symmetry as reflected in the clavicle angle correlate weakly with radiographic measures. This suggests correction of trapezial prominence may be more predictable compared to clavicle angulation following scoliosis surgery.
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ABSTRACT: Study Design. Retrospective case series of surgically treated adolescent scoliosis patients.Objective. To establish a new radiographic measurement method to determine the best preoperative predictor of post-operation shoulder balance.Summary of Background Data. Shoulder balance is an important aspect of the overall cosmetic balance in patients with adolescent idiopathic scoliosis. Despite recent reports, it is still difficult to accurately estimate the post-operation shoulder balanceMaterials and Methods. A retrospective review of 89 consecutive patients who had thoracic fusion with a minimum 2-year follow-up (mean 3.1 years) was conducted to investigate the radiographic measurements and patient demographics. The shoulder height difference (SHD) was measured as the graded height difference of the soft tissue shadows. SHD>2 cm was considered an unbalanced shoulder. The clavicle chest cage angle difference (CCAD) was established and evaluated. The CCAD was graded as Grade A: no imbalance (<0 degrees), Grade B: mild imbalance (0-10 degrees), and grade C: significant imbalance (> 10 degrees).Results. Of 89 patients, 22 patients had a moderate or significant shoulder height difference at 2 yrs post-operation and were categorized as the unbalanced shoulder group (unbalanced SD). A significant difference was observed in pre-operation CCAD between the balanced and unbalanced SD groups (p = 0.01). The intra-class correlation coefficient for CCAD was 0.94 among the observers. CCAD was consistent from the pre-operation to the final post-operation follow-ups in both groups. The classification of the CCAD pre-operation indicated that 12/22 (54.4%) patients who were classified in the post-operation unbalanced SD group showed Grade 3 CCAD pre-operation, while only 9/67 (13.4%) patients who were classified in the post-operation balanced SD group had Grade 3 CCAD pre-operation.Conclusion. The developed method to predict postoperative shoulder balance was demonstrated to be easy to perform, reliable, and practical. Additionally, we classified the estimation of post-operation shoulder imbalance by pre-operation CCAD. The results of this comprehensive review will guide spinal surgeons in their pre-operative planning and in the surgical management of AIS to reduce post-operative shoulder imbalance.
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ABSTRACT: Study Design. Retrospective case series of surgically treated adolescent scoliosis patientsObjective. To assess the prevalence and independent risk factors of post-operation shoulder imbalance in surgically treated adolescent patients with idiopathic scoliosisSummary of Background Data. Despite recent reports that have identified risk factors for post-operation shoulder imbalance, the relative risks remain unclear.Methods. A retrospective review of 85 consecutive patients treated with thoracic fusion with a minimum 2-year follow-up (mean 3.1 years) was conducted to investigate the patient radiographic measurements and demographics. Shoulder height difference (SHD) was measured as the graded height difference of the soft tissue shadows. A SHD>2 cm indicated an unbalanced shoulder. Patient demographics and radiographic data were studied to determine risk factors for post-operation SHD. The potential risk factors included age, gender, Risser sign, Cobb angle, flexibility, apical vertebral rotation (AVR) of the main curve, UIV level, SHD, and clavicle chest cage angle difference (CCAD). Uni-variate and multi-variate logistic regression analyses were performed to determine the independent risk factors for post-operation shoulder imbalance.Results. Of the 85 patients, 21 patients presented post-operation shoulder imbalance. The uni-variate analysis indicated age, Risser sign, Cobb angle of the main curve, AVR of the main curve, and CCAD as risk factors, but the multi-variate logistic regression analysis showed that only AVR of the main curve and CCAD were independent risk factors for post-operation shoulder imbalance (AVR, p = 0.04, OR: 3.54; CCAD, p = 0.01, OR: 5.10).Conclusions. Post-operation shoulder imbalance was observed in 25% of the surgically treated adolescent patients. The CCAD and AVR of the main thoracic curve were independent risk factors for post-operation shoulder imbalance in surgically treated AIS patients. The significant correlation between CCAD and post-operation shoulder imbalance seen in the present study strongly suggests that the relationship of the shoulder girdle and chest cage has a role in maintaining shoulder balance.
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ABSTRACT: Study Design: Retrospective cohort study. Objective: To study the relationship between the proximal spine and shoulder levels in adolescent idiopathic scoliosis (AIS). Summary of Background Data: It has been frequently observed that the shoulder levels do not correspond to the spinal curve direction in AIS. Materials and Methods: Eighty-five operated cases of AIS were analyzed retrospectively of which 69 were Lenke type I and II curves. Preoperative anteroposterior standing x-rays of the spine and clinical photographs were studied. T1 tilt and intercoracoid line (ICL) tilt and their mutual relationship were documented. The curve type (Lenke), magnitude, and direction of the proximal and main thoracic (PT and MT) curves were also noted. Results: The shoulder level as depicted by the ICL showed 3 patterns—horizontal, left side elevated, or right side elevated. The T1-ICL relationship was either concordant or discordant. In the concordant case the T1 was tilted to the same side as the ICL; and vice versa in the discordant. The shoulder level was dependent on the MT curve if the ICL tilted to the same side as the MT curve and it was dependent on the PT curve if it tilted to the same side as the PT curve. This relationship appeared unrelated to curve type. Conclusions: Preoperative shoulder levels in AIS may be concordant with the T1 or discordant—each can have left or right shoulder elevation or balanced shoulders. Further, the shoulder might be MT dependent or PT dependent. Theoretically therefore, surgical balancing of the shoulder and upper instrumented vertebra placement should not depend only on the magnitude and stiffness of the PT curve.
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